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Thesis Paper
Alien Invasive Plant Species in Bangladesh and Their
Impact on Indigenous Plant Biodiversity
A dissertation presented (by Mohammad Redowan) as a requirement for the degree of 1-year professional Master of Science (M.Sc.) degree
in Forestry, Institute of Forestry & Environmental Sciences,
University of Chittagong Chittagong, Bangladesh
Guided By
Dr. Mohammed Kamal Hossain
Associate Professor
Institute of Forestry and
Environmental Sciences
University of Chittagong
Submitted by
Mohammad Redowan
MSc student
Session: 2004-2005
Institute of Forestry and
Environmental Sciences
University of Chittagong
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Chapter 1: Introduction
1.1. Introduction
The word ‘alien’ denotes ‘foreign’ or ‘exotic’ and ‘invasive’ indicates which
violates the rights of others’. So, alien invasive species are those that occur outside their
natural range or have established themselves accidentally or introduced deliberately to any
land and being established there suppressing the native vegetation. An alien species, also
called ‘non-native’, ‘non-indigenous’, or ‘exotic’, is one that is introduced, accidentally or
purposefully, into an ecosystem in which it did not evolve. Alien or exotic species can
come from other continents, other countries and even other parts of the same country
(Winkler and Herding, 2004). Here ‘foreign’ or ‘exotic’ actually is not justified by
political boundary rather natural range of origin of the plants and their movement outside
to that range is the point of concern.
All alien plants may be exotic, but all exotic plants may not be alien. Alien species
do not always become invasive. To conserve native species and ecosystems appropriately,
we must judge which alien species should be given the highest priority as “invasive alien
species” in management programs. Native plant species may occasionally show invasive
behaviour in ecosystems modified by human activities (Brisson, 2003).
Invasive alien species are those that threaten the existence of native plants and
animals or other aspects of biodiversity and occur in all groups of plants and animals
(Gregorio, 2002). The problem of invasive species is increasingly being recognized around
the world. Invasive alien species can cause severe disruption to both natural and managed
ecosystems (Weber, 2003).
Awareness of the impacts of invasive alien species on biodiversity and human
livelihoods has grown greatly. Information on the topic has burgeoned, invasion biology
has become a recognized science and local actions and international agreements against
IAS have increased (Joan, 2003). Invasive alien species (IAS) are considered to be the
second largest threat for biodiversity loss on a worldwide scale as is reflected in recent
international conventions and politics (CBD, 2001).
The issue of alien invasive species and their use or abuse has generated a lot of
controversy all around the world including Bangladesh. Invasion biology has progressed
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substantially in the past decade (Mackinnon, 2002). Invasions are occurring around the
word at an unprecedented rate and scale (Anon, 2003). But the nation’s approach to
invasive species remains in the dark.
From over a long time, many alien species have been introduced in Bangladesh
with the belief that it would increase the total production (Das, 1982). Most of them have
become naturalized and integrated into the local ecosystem and have little adverse impacts
on the ecosystem but many of them have become invasive. They are damaging our
ecosystem, invading agriculture or natural habitat and displacing indigenous species.
Increasing human population and per capita consumption, leading to expansion of global
trade and increases in human mobility have resulted in unprecedented invasion by
nonnative species.
These biological invasions produce severe, often irreversible impacts on
agriculture, recreation, and our natural resources. Invasive species threaten biodiversity,
habitat quality, and ecosystem function (Daehler and Carino, 1999). They are the second
most important threat to native species, behind habitat destruction, contributing to the
decline of endangered and threatened species. Introduced species also present an ever-
increasing threat to food and fiber production (Gregorio, 2002). In Bangladesh, like other
parts of the world, the economic costs of nonnative species invasions is anticipated to
millions of taka each year .If they are given an inch, they will take an acre!
Invasions by both native and exotic species potentially can threaten natural
communities (Stanton et al., 2003). Invasives threaten the productivity of the soils and
waters upon which our economies and we depend. They imperil the native species that
make this country unique. In sum, the devastation done by non-native invasive species is
one of the most serious and least-recognized tragedies of our time (Yan, 2003). Invasive
species can change the ecosystem composition and function; reduce the indigenous
biological diversity that in extreme case may lead to local extinction of species.
Unfortunately a large number of alien species have been introduced in our
ecosystems without proper scientific investigation on possible impacts. Thus, not all, but a
good number of the species so far been introduced in Bangladesh have become invasive.
The incredible variety of species that have the ability not just to travel in ingenious ways,
but also to establish, thrive and dominate in new places. More than 300 exotic species are
supposed to either wildly growing or cultivated as an economic crop in Bangladesh. Of
them the herbaceous and lianas are the dominant exotics followed by trees an shrubs
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(Islam, 1991). Most of the plants have been brought by settlers, invaders, seamen and
traders. The origins of most of the exotics are Africa, Australia and South America. In
Bangladesh there are no detail records of exotic plants except the plants of some common
and few cultivated ones (Das, 1982). Though the undisturbed natural forests are resistant
to such invasion, but the degraded and secondary forest areas and wastelands are
aggressively invaded by the invasive species.
Foresters have consistently introduced exotic trees for plantations. There is often a
short-term advantage in planting a species in the place where its natural pests and diseases
are absent. In some cases such species spread out of control, displacing natural vegetation
and profoundly changing the natural ecology. Exotic species are not automatically “bad”.
Most of our important food crops and domesticated animals are exotic. But, both exotic
and native species become problems when they are invasive (Mackinnon, 2002).
Despite frequent implied association in the literature, invasiveness and exotic
status are not really closely correlated. Most aliens in Bangladesh are not exotic weeds,
whilst some natives are. The term ‘invasive’ should only be applied to alien species, whilst
for native we should use the less pejorative term ‘expanding’, which is more like semantic
politics than an objective assessment. Invasive alien species in this literature would remain
restricted to Invasive Alien Plant Species only.
1.2. Objectives:
1. To identify the possible invasive plant species in Bangladesh;
2. To determine the distribution of invasive plant species in Bangladesh;
3. To determine the effect of invasive trees Acicia auriculiformis, Eucalyptus
camaldulensis and Melaleuca leucadendron on indigenous plants.
4. To study the habitat, vegetative characteristics, growth and biomass of
invasive shrubs Lantana camara, Eupatorium odoratum, Ipomea carnea and
Mikania cordata and their impact on indigenous plant species.
1.3. Rationale of the research
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Biological invasion is a worldwide problem. Bangladesh like many other countries
of the world faces the problem with alien invasive species whether these are plants or
animals. These invasive species are causing huge loss to our ecosystem, which is not yet
quantified, but the damage to our environment and biodiversity is only felt. Many species
of plants has been introduced here in Bangladesh, many of which are blamed rigorously as
the invasive plants, which are aggressively invading the ecosystems. Some species like
Acacia auriculiformis, Melaleuca leucodendron, Imperata cylindrica, Lantana camara,
Mikania coudata, Ipomea carnea, Eupatorium odoratum have notorious past of ecosystem
invasion in different countries of the world. Lantana camara, Eupatorium odoratum,
Mikania cordata, Ipomea carnea etc are self-spreading aggressive weeds in Bangladesh
ecosystem like many other countries. Imperate cylindrica is a notorious weed in 73
countries of the world (Holm et al., 1977). Eucalyptus and Acacia species have already
spreaded to more than 80 countries of the world (Anon, 2003). Melaleuca also constitute
significant health hazard because of flowers and new foliage airborne substance
production that cause severe asthma-like symptom in sensitive people and also displace
native vegetation (Pernas and Francois, 2003).
But Acacia auriculiformis, Eucalyptus camaldulensis, Acacia mangium etc.
constitutes a substantial part of the plantation program of Bangladesh while they are
problem species in many countries. Lantana camara, Eupatorium odoratum, Mikania
cordata, Ipomea carnea etc are common invasive weeds of fallow land, waste land,
roadside, grassland, canal bank and forests in Bangladesh. Lantana camara and
Eupatorium odoratum are listed weed of 100 of the world’s most invasive species (IUCN, 2003).
Within the last two or three years the work on the problems caused by invasive alien
species has intensified (Ema and Alzbeta, 2004). Attempt has been made in this research
work to investigate the phenomena as what impacts do the trees, Acacia auriculiformis,
Eucalyptus camaldulensis and Melaleuca leucodendron impose to indigenous plant
biodiversity. The vegetative characteristics of Lantana camara, Eupatorium odoratum,
Ipomea carnea and Mikania cordata have been recorded with qualitative observational effect
of these species on nearby co growing vegetation, habitat and indigenous biodiversity. The
finding of the research work can, at least help scientists throughout the country conscious of
biological invasion and can be a help of the policy makers in designing national strategy to
combat biological invasion in Bangladesh and conserve indigenous biodiversity.
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Part 2: Review of
literature
Chapter 2: Review of literature
2.1. What are Alien Invasive Species?
2.1.1. Alien Species: (synonyms: non-native, non-indigenous, foreign, exotic):
a species, subspecies, or lower taxon introduced outside its normal past or present
distribution; includes any part, gametes, seeds, eggs, or propagules of such species that
might survive and subsequently reproduce (CBD, 2001).
An alien species, also called non-native, non-indigenous, or exotic, is one that is
introduced, accidentally or purposefully, into an ecosystem in which it did not evolve.
Alien or exotic species can come from other continents, other countries and even other
parts of the subcontinent. Alien species are those that occur outside their natural range or
have established themselves accidentally or introduced deliberately (Gregorio, 2002) Non-
native plants are those that exist outside their natural range or natural zone of dispersal and
include domesticated and undomesticated species and all hybrids, except those that
naturally occur between native species (Kandasamy et al., 2003).
2.1.2. Invasive Alien Species (IAS): Various authors and organizations
defined invasive alien species differently as given below:
An “invasive alien species” is an alien species whose introduction or spread
threatens biological diversity (Ecological Society of Japan, 2002; UNEP, 2002). It can
safely be assumed that these species are invasive since they often competitively exclude
native plants (e.g. Miyawaki and Washitani, 1996; Muranaka and Washitani, 2001).
Therefore, alien plants that do not form the dominant vegetation should not be considered
as “invasive.” Propagule pressure is widely recognized as a fundamental driver of invasion
(Williamson, 1996).
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An "invasive species" is defined as a species that is 1) non-native (or alien) to the
ecosystem under consideration and 2) whose introduction causes or is likely to cause
economic or environmental harm or harm to human health. (Executive Order 13112).
Invasive species can be plants, animals, and other organisms (e.g., microbes). Human
actions are the primary means of invasive species introductions. An invasive species is a
species occurring as a result of human activities beyond its accepted normal distribution
and which threatens valued environmental, agricultural or personal resources by the
damage it cause. Invasive alien species (IAS) are those species, which have been
introduced outside their normal current or past range, and whose introduction and spread
cause harm to human health, the economy, and or the environment. They pose particular
threats to plant biodiversity and to the plant habitats on which we and millions of other
species depend for survival (Daehler and Carino, 1999).
Invasive alien species (IAS) are those species, which have been introduced outside
their normal current or past range, and whose introduction and spread cause harm to
human health, the economy and or the environment. They pose particular threats to plant
biodiversity and to the plant habitats on which we and millions of other species depend for
survival. IAS may have been introduced accidentally or intentionally, and they may be
plants, animals, fungi, bacteria, blue-green algae or viruses, IAS from all these groups are
an immense threat to the world’s plant diversity. Apart from habitat destruction, IAS are
the single biggest reason for the accelerating biodiversity crisis. Invasions of alien species
are also made worse by many of the other pressures facing the planet-habitat degradation,
climate change, urban sprawl and the impact of globalization and trade on natural
resources and biodiversity, both wild and domesticated (www.gisp.org).
Whether they are called invasive, nonnative, exotic, alien or nonindigenous,
introduced species are those that evolved elsewhere and have been purposely or
accidentally relocated. While some species have invaded habitats on their own (e.g.
migrating wildlife, plants and animals rafting on floating debris), human exploration and
colonization have dramatically increased the diversity and scale of invasions by exotic
species. Introduced species often find no natural enemies in their new habitat and therefore
spread easily and quickly (Blair, 1996).
Invasive species are ‘alien’ species whose introduction does or is likely to cause
economic or environmental harm or harm to human health”(Binggeli and Hamilton, 1993).
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Invasive alien species (IAS) are those that threaten the existence of native plants
and animals or other aspects of biodiversity, and occur in all groups of plants and animals.
The Species Survival Commission of IUCN reports that as competitors, predators,
pathogens and parasites, alien species have invaded almost every type of native
ecosystem, and caused hundreds of extinctions. Accordingly, their impacts are immense,
insidious and usually irreversible (Gregorio, 2002).
An alien species whose establishment and spread threaten ecosystems, habitats or
species with economic or environmental harm. These are addressed under Article 8(h) of
the CBD, which states that:
"Each Contracting Party shall, as far as possible and as appropriate:
...........(h) Prevent the introduction of control or eradicate those alien species which
threaten ecosystems, habitats or species."(Shine at al., 2000)
Many exotic plants are also successful colonizers of disturbances, however, and
may in turn compete with native populations (Martin et al., 2003). Many factors,
especially climate, soils and other environmental conditions can potentially influence the
number of exotic species that become established in an area. It is therefore perhaps
surprising that human population size often plays the most dominant role in determining
exotic species richness (Mckinney, 2003). Thus, predicting the ultimate impact of
disturbance requires an understanding of the differential responses of natives and exotics,
which is essential to managing, endangered plant populations in, invaded plant
communities (Mcgraw, 2003). Invasive exotic trees, especially those species that persist
during succession, may have far longer and more pronounced effects (Martin et al., 2003).
Many species of plants can crowd ecosystem, cause problems with forestation,
biodiversity conservation and have local impacts on peoples' uses of lands – yet they are
not alien invasive species. On reflection, the invasive ability of natives is not surprising.
These are plants that have proven reproductive ability within their climatic range and they
are often very able to exploit opportunities created by, say, excessive habitat disturbance
or land use change. They are often local species that respond to some changing
circumstance that makes them more obvious and deleterious to the objectives of land
management. They are usually called WEEDS - not alien invasives. A bright example of
problem native plant is cogon grass (Imperata cylindrica), a native plant of South-East
Asia, is considered as a notorious invasive species in the U.S.A. they are also useful
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wetland species that provide goods and services to people and biodiversity, while also
causing problems when they occupy new areas or increase their densities from what was
considered "normal".
2.1.3. Types of Invasive Alien Species and the ecosystem they
invade:
IAS may have been introduced accidentally or intentionally, and they may be
plants, animals, fungi, bacteria, blue-green algae or viruses (Akerson, 2003). IAS from all
these groups is an immense threat to the world’s plant diversity. Invasive Alien Species
(IAS) occur in almost every watershed and ecosystem, and represent many taxonomic
groups, including mammals, birds, reptiles, amphibians, fishes; arthropods and
crustaceans; algae, ferns and seed plants; and fungi, viruses, bacteria, and other micro-
organisms (Yan, 2003). The categories “invasive alien species,” “agricultural weeds,”
“revegetation species,” often overlap with each other, and consequently a species can
belong to more than one category (Ecological Society of Japan, 2002; UNEP, 2002).
2.2. Biological invasion is a worldwide problem
Biological invasion of ecosystem by invasive alien species (IAS) is a worldwide
problem, e.g. more than 30% of the species known from the small Indian Ocean Island of
Mauritianas are threatened with extension, principally through the effects of invasive alien
species (Sawmy, 2004). Some major culprites like Eichhornea crassipes, Pistia strateotes,
Melaleuca, Eucalyptus, Kudzu, Japanese knot weed Cogongrass (imperata cylyndrica)
etc. are major ecological problem to many countries of the world. Threat due to invasive
species on native biological diversity is increasing at an alarming rate in tropics (Allesh et
al., 2003). In South East Asia alone, according to MacKinnon (2002), IAS are causing
billions of dollars worth of damages. Invasive Alien Species (IAS) are found in all
taxonomic grounds and have affected native biota in virtually every ecosystem type on
earth. They are a major threat on a global scale and addressing IAS is of major
significance to biodiversity and sustainable livelihood outcomes. Invasive non-native plant
species are causing worldwide economic and ecological damage (Gregorio, 2002). As an
example, the State of Florida spends over 20 million dollars each year to manage just a
few of the worst problem species (Clark and Randall, 2003). Economical and ecological
losses caused by invasive species make successful control of invasions a desirable aim
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(Nehrbass et al., 2003). Next to the loss of habitats the increasing number of alien species
influences and changes worldwide native flora and fauna.
0ne of the major threats to biodiversity in the ASEAN region as well as globally is
the introduction of exotic species into the region. For the past 40 years, the rate of and
risks associated with biotic invaders have increased enormously because of human
population growth, rapid movement of people, and alteration of the environment
(Gregorio, 2002). Political boundaries are indeed porous to the intentional and
unintentional movement of species from various ecosystems in all parts of the world. And
in both ecological and economic terms, the scope and cost of biological alien invasions are
enormous (Gregorio, 2002). Although invasive alien species are a growing reality in
Bangladesh, they are still widely unnoticed by most and expanding over precious natural
resources and species.
2.3. Introduction of alien or exotic trees in the plantation
forestry of Bangladesh
Bangladesh is one of the countries to initially sign the convention on Biological
Diversity pledging to conserve the natural and biological resources. But, plantation of
woodlot in Bangladesh is antagonistic to the main premise of the convention. A big
criticism of woodlot that it is bringing in exotic species, which is damaging for bio-
diversity and when the exotic trees mature they might not prove fit for rural and wild life.
(Ammen, 1990). Teak (Tectona grandis) was the first tree introduced on hill forest
ecosystems of Bangladesh in 1871 from Myanmar (Burma). Main object of management
was and is to replace these heterogenous forests by a plantation of alien fast growing
species The rationale of clear-felling the Dipterocarp dominate natural heterogeneous
forests was that the introduced valuable timber species will be more productive than the
natural tropical wet evergreen and semi-evergreen forests (Hossain, 2004). The yield and
management of the heterogeneous forests of Bangladesh is very low and complicated.
Therefore, the need for the introduction of valuable monoculture of exotics of indigenous
or mixtures of both the species was felt at the very beginning of the scientific management
of these forests. Present day Government policy is to maximize the productivity of the
existing forests and development of new high yielding forests both on private and public
land. Introduction of fast growing exotic and multipurpose tree species both in rural and
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national forests was given priority during the 3rd 5-year Plan period (1985-90). For that
purpose, introduction of many fast growing exotic species was made. The main constraint
with these species is the collection of seeds of appropriate provenances. Exotic species
were introduced into the country without any proper documentation. Without proper
impact assessment in place, the Government had encouraged the introduction of species
with high growth rate to increase food productivity to meet the needs of the ever-
increasing population (Ameen, 1999). The most prevalent economic uses of invasive plant
species are ornamentals (40% of species), followed by erosion control (12%) and wood
production (9.5%)(Weber, 2003).
The first attempt to introduce Teak was successful in early seventies of nineteenth
century. Subsequently from 1930 and onwards, a large number of species have been tried
in different Silvicultural Research stations for searching out suitable exotics as well as
indigenous species. Out of these trials, Albizia moluccana (Acacia arabica, Anarcardium
occidentale, Dalbergia sissoo, Eucalyptus camaldulensis, Elaeis guinensis, Hevea
braziliensis, Leucaen leucocephala, Morus alba, Pinus caribaea (variety Hondurensis),
Swietenia macrophylla, Xylia dolabriformis have been successfully introduced in our
plantations (Das, 1982). Bangladesh being a member of the International Provenance
Research Programme has received a number of provenances of Pinus caribaea, Pinus
oocarpa, Tectona grandis, Albizia procera, Gmelina arborea which have been put
already in the nursery and it will go the field for provenance trials.
2.3.1. A short account of the alien and exotic trees so far introduced in
the plantation forestry of Bangladesh
From 1871 to 2005 knowledge about the forests of Bangladesh has increased in
many directions. Attempts have been made to replace the heterogeneous low yield forests
by valuable indigenous species as well as by exotic species since the beginning of the
scientific management of the forest here. Teak (Tectona grandis) was first introduced in
Bangladesh in 1871 from Myanmar (Burma). So, 1871 is the beginning point of plant
introduction of Bangladesh. Except Teak and Mahagony, the works on exotics were
organised mostly from 1930 and onwards. The exotic species, which have been
successfully introduced in the plantations, have been mentioned:
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1. Albizia moluccana Miq; Synonyms are A. falcate Backer and A. falcataria Fosbrg
a native of Moluccea was first introduced in seventies. It was planted on an experimental
basis at Lawachara in the Sylhet Forest Division. Subsequently it has been planted in
various forests areas of Bangladesh. It is a very fast growing species.
2. Acacia arabica & A. catechu: These species are the native of the drier part of the
sub-continent. Its introduction into the northern districts of Bangladesh dates back perhaps
in the nineteenth century. It is being cultivated by the farmers in the boundary of their
fields in the northern districts. A. arabica have been introduced in the late sixties in the
coastal afforestation works also.
3. Anacardium occidentale (Kaju badam); This species was first introduced in the
Chittagong Coastal areas by the Portuguese, perhaps in the later part of eighteenth century.
As a cash crop it has been introduced in Bangladesh in late fifties. The seeds were brought
from Ceylon. Its capacity to thrive in poor soils is excellent and yield of fruit is also good.
Plantation raised haphazardly is not economic at all. It needs an organised and
concentrated blocks of plantation which will be economically viable.
4. Dalbergia sissoo (Shisam): The species was introduced in this part as a roadside
tree in the northern districts. The seeds were brought from India. But now it is being
planted as a plantation species. This is being also planted in the village groves. The growth
rate is less about 1/2 Mean Annual Increment (M.A.I) over d.b.h. The growth rate here is
better than natural habitat.
5. Eucalyptus sp; Sometime in the 1930’s Eucalyptus citriodora was haphazardly
introduced into eastern Bangladesh by tea estates as an ornamental. As a forest species, it
was tried in the year 1938. This species was spread throughout Bangladesh by botanists,
foresters, gardeners and other people, but no formal plantations were developed (Davidson
and Das, 1985). First interest in other species of eucalypts was recorded in 1963 when
germination tests of three species, E. citriodora, E. tereticornis and E. botryoides were
conducted in the Silvicultural Research stations in Mymensingh and Chittagong. From
then on until 1984 about 37 species were introduced and tried . From the growth record it
appeared that it can establish in the climate and soil of Bangladesh. But, it was planted
mostly as an ornamental plant instead of forest species. It is now being also tried as forest
species.
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No attempt was made to consider Eucalyptus as a forest species till 1962. In the year
1962, seeds of Eucalyptus siderophloia, E. robusta, E. tereticornis, E. glabulus, E. rubida,
E. gigantea, E. obliqua, E. grandis, E. citriodora, E. botryoides, E. saligna, E.
camaldulensis were received from the C.S.I.R.O., Australia. Seeds were in small quantity
and were sown in the Silvicultural Research Stations at Hathazari, and Charaljani. On the
preliminary observations, it was found that E. robusta, E. tereticornis, E. glabulus, E.
rubida, E. grandis, E. saligna, E. botryoides, E. gigantea, E. citriodora can be grown.
Due to lack of subsequent persuation till 1976, no further progress was made. However, in
the meantime, Forest Research Institute, Chittagong tried few species like Eucalyptus
grandis, E. globules, E. alba, E. gigantea, etc., in the year 1969 in their campus. Here also
no subsequent persuation was made.
With the assistance of UNDP again the works on Eucalyptus species started in 1978 at
Bangladesh Forest Research Institute (BFRI). 85 seed lots of 12 species: Eucalyptus
camaldulensis, E. brassiana, E. teretocornis, E. robusta, E. saligna, E. molucana, E.
grandis, E. citriodora, E. maculata, E. acmeniodes and E. pilularis were tried in species
elimitation trial at Keochia, Hathazari, Hazarikhil, Lawachara, Charkai and Chittagong
Headquarter Stations. Out of these trials, E. camaldulensis, E. brassiana, E. citriodora, E.
robusta, and E. tereticornis have shown good growth. Eucalyptus camaldulensis has
shown over 1 MAI growth on dbh. This is the most important one out of these 5 species
tried recently. One of these 5 species, E. camaldulensis (variety petford) is being planted
in the plantations on small scale. Over 100.0 acres plantations of E. camaldulensis and E.
brassiana have been raised in different Silvicultural Research Stations. Seedlings of these
two species have also been supplied to different Forest Divisions for raising small-scale
plantations. Collection of seed is the number one problem. It is under our consideration
that we should develop our own seed sources through the seed Orchard Division.
6. Elaeis guinensis (Oil-palm): About 2 Ibs. seeds of oil-palm (E. guinensis variety
Dura) were received from Malaysia by the Silvicultural Research Division in the year
1964. It was tried at Hazarikhil and Rasulpur Silvicultural Research stations. The plants
planted at Hazarikhil started giving fruits in the year 1969. Later on, the Rubber Planting
Project also Planted some Dura variety brought from Malaysia. The fruits produced by this
plants were analysed and found that the yield of oil is comparable to those of Malaysia.
The species has gone now to plantations.
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7. Hevea braziliensis (Para rubber): The species was introduced in tea-gardens of
Bangladesh around 1910 in the districts of Sylhet and Chittagong from the seeds collected
from Calcutta Botanical Graden. Subsequently a few trees were planted at Hazarikhil
Silvicultural Research Garden. Being encouraged in 1959 from the clones brought from
Malaysia, the larger scale plantations have been undertaken by the Forest Industries
Development Corporation.
8. Leucaena leucocephala: Ipil Ipil is the common name used in the Philippines for
the exotic leguminous species Leucaena leucocephala which is also exotic to Bangladesh.
The sources of early introductions are not recorded and like many such introductions,
these have developed into a local rice. In Bangladesh, the species is frequently found in
Coastal areas where it is known as Teli Kadam (presumably because the flowers are
similar to Anthocephalus kadamba). It grows into a shrub about 15 to 20 tall. L.
leucocephala has proved itself a valuable, fast growing plantation species in the
Philippines. The timber is used for fuel-wood. The foliage provides high protein fodder for
cattle. It has also been shown to be a useful green manure crop in Hawaii and a valuable
cattle fodder in Australia. Though L. leucocephala has only been grown in Malaysia for
few years, it is already an important cattle and poultry feed. It could, therefore, be an
important species in Bangladesh where there is considerable pressure on the existing forest
for fuelwood and also for grazing land, both factors critically influence forest re-growth.
Small quantities of seed of varieties K –8 (called the “Hawaican Giant”), K –28 and K-67
were obtained from the Philippines in August 1978. These were tried at different.
Silvicultural Research stations. The results are encouraging in the plain land forests, in
homestead, on the canal and riverbanks etc. where the soil PH is over 5.5 and needs
further trial in the hill forests.
9. Pinus sp.: Pinus caribaea (from Honduras) was first tried at Hazarikhil in the year
1940. Out of these trials, two seedlings survived. These two seedlings have attained a
height of 48 and g.b.h. 32 at the age of 38 years. The second batch Pines (Pinus elliottii)
seed was collected through the Forestry Adviser, AID and the seeds were sown in the 3rd
week of November 1961. The germination was over 80%. The seedlings raised were
planted in the Forest Research Institute campus mostly. It has been found unsuitable for
our purpose. The third batch of seed was received by the D.F.O, Silvicultural Researh
Division in 1962. These include few grams of each Pinus pinaster, Pinus radiata, Pinus
thumbergii, Pinus insularis, Pinus pseudostrobus, Pinus merkusii, Pinus massociana,
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Pinus michoeana, Pinus douglansiana, Pinus montezume, Pinus caribaea, Pinus elliottii,
Pinus canariensis, Pinus ayachuta. Amongst these species, Pinus caribeae, Pinus radiata,
Pinus insularis were found to give good indication in the nursery. An acre of Pinus
radiata plantation was raised in the year 1963. Subsequently no care was taken to maintain
and no further trial was made with these species. The 4th batch of seeds was received
through the F.A.O / U.N.D.P. Project Manager in January 1970. This 4th batch included
Pinus caribeae, Pinus oocarpa, Pinus khassya, Pinus radiata and Pinus merkusii. The
seedlings were raised in polybags in the winter and were planted in July 1971 mostly in
Bangladesh Forest Research Institute (BFRI) campus. Amongst these, Pinus caribeae
(mostly Honduransis) and Pinus oocarpa have shown good growth. M.A.I. of Pinus
caribeae is near to 1 over d.b.h. estimates of yield from the in-sufficient data are highly
speculative. This projected yield comes about 25-27 m3 per hectare per year (e.g. 350-380
Cft per acre per year), but 17 m3 per hectare (240 Cft per acre) will be on the safer side. In
July 1974 Pinus caribeae and Pinus oocarpa were also planted in the F.R.I. campus,
Dariadighi, Barduara and Kaptai East Range on trial basis. About 50.0 acres of Pinus
caribeae plantations have been raised in different Silvicultural Research Stations during
the past two years from the seeds obtained through various agencies like F.A.O / U.N.D.P.
10. Swietenia macrophylla: The species was planted at Kaptai in the year 1891. The
growth is quite satisfactory. The species is now widely planted along road sides,
homestead and forest areas.
11. Xylia dolabriformis: This species was first tried at Lawachara and Hazarikhil
Silvicultural Research Stations from the seeds brought from Myanmar. Subsequently the
species was tried at Charaljani Silvicultural Reasearch Stations. The species have been
recommended for plantation in order to supply poles for the Rural Electrification Board
(REB).
2.3.2. Different stages through which the exotic species have been
passing:
2.3.2.1. Exotic species, which proved successful in trials and have already been
introduced in the plantations:
I. Tectona grandis (Myanmar and India)
II. Hevea brazilensis (Malaya)
III. Anacardium occidentale (Ceylon)
16
IV. Albizia moluccana (Not known)
V. Dalbergia sissoo (India and Pakistan)
VI. Swietenia macrophylla (Perhaps – Honduras)
VII. Acacia arabica (Not known – probably India)
VIII. Acacia catechu (Not known – probably India)
2.3.2.2. Exotic species which proved successful and have already been
recommended for introduction in the plantation:
I. Eucalyptus camaldulensis (Petford, Australia)
II. Morus indica (India and Pakistan)
III. Pinus caribaea (Hondurensis) (Honduras)
IV. Xylia dolabriformis (Myanmar)
V. Leucaena leucocephala (Philippines)
2.3.2.3. Exotics and exotic provenances which were under arboreta trials but were not
tried in plantations and now needs small-scale trial for further assessment:
I. Artocarpus fraxinlfolius (Garo Hills-Provenances)
II. Ailanthus grandis (Sadya and Assam)
III. Alurites fordii (Malaya)
IV. Alurites montanes (Malaya)
V. Alstonia scholaris (Kachar Provinances)
VI. Anogeissus acuminata wall (Central India- Provenances)
VII. Artocarpus hirsuta (W. Ghat and India)
VIII. Chcikrassia tabularis (Darang, Provenances, Assam)
IX. Calorophera excelsa (Uganda)
X. Dalbergia latifolia (India)
XI. Eucalyptus botryoides (Australia)
XII. grandis ()
XIII. robusta ()
XIV. rubida ()
XV. saligna ()
XVI. alba ()
XVII. citriodora ()
XVIII. Eugenia alba ()
XIX. Lagerstroemia hypoleuca (Andaman)
17
XX. Melia indica (Malaya-Provenances)
XXI. Pterocarpus santalinas (S. India)
XXII. Pterocarpus marsumpium ()
XXIII. Sterculia campansulata (Andaman)
XXIV. Swietenia mahagoni (Honduras)
XXV. Pinus oocarpa ()
XXVI. Pinus khasya (Thailand)
XXVII. Pinus radiata (Tanzania)
XXVIII. Pinus markusii (Thailand)
XXIX. Podocarpus nerifoliua (Kachar, Provenances, Assam)
2.3.2.4. Exotic species and exotic provenances, which were under arboreta trial
but does not require plantation trial due to their poor performances:
I. Acacia senegal (West Africa)
II. Canarium euphylum (Andamans)
III. Dipterocarpus griffithii (Burma)
IV. Eucalyptus globules (Australia)
V. maculata ()
VI. sededorophloia ()
VII. umbellate ()
VIII. Grevillea robusta ()
IX. Mangliotia insignis (Lakhshmipur)
X. Mansomia altissima (Nigeria)
XI. Michelia insignis (Tejpur, Assam)
XII. oblonga ()
XIII. clifolia (South India)
XIV. Pancevia rubignosa (Assam)
XV. Phoebe goalparansis ()
XVI. Polygala arillata (Ceylon)
XVII. Santalum album (S. India)
XVIII. Shorea assamica (Assam)
XIX. Pinus insularis (Not known)
XX. longifolia (India)
XXI. sinensis (Mauritins)
18
XXII. thumbergii (Not known)
XXIII. elliottii (U.S.A)
XXIV. Araucaria angustifolia (Not known)
XXV. cunninghamii ()
2.3.2.5. The following exotic species failed to grow due to various reasons:
I. Acacia karoo
II. cyanophylla
III. Calamus scipionum (Molucca)
IV. Populus nigra
V. wislengii
VI. trichcearpa
VII. Populus clone – 214
VIII. - 262
IX. Salix species (Willows)
X. Pinus pinaster
XI. Pseudostrobus
XII. michocana
XIII. douglansiana
XIV. montezume
XV. canariansis
XVI. ayachute
XVII. Agathis palmestromii
XVIII. Podocarpus falcatus
XIX. Taxodium spp
2.3.2.6. The following exotic species and exotic provenances are under trial in the
nursery and arboretum:
1. Gmelina arborea: Bangladesh is a member of International Provenances Trial of
Forest Tree species. Under this programme, 15 provenances of Gmelina arborea were
received from Brazil, India, Srilanka and Thailand. Seeds have been sown in the nursery.
The seedlings raised will be planted in the field during the coming planting season.
One clone of gamar received from Nigeria has also been planted in the field.
19
2. Tectona grandis: Seeds of 6 provenances of Tectona grandis from India and Thailand
have been put in the nursery. The seedlings will go to the field planting during the coming
rainy season.
3. Pinus caribeae Var: hondurensis: As a member of the International Provenance Trial
Programme, as stated earlier, provinces of Pinus caribaea were received from the
Commonwealth Forestry Institute. Out of these 7 Provenances received, 4 provenances
were from Honduras, 1 from Nicaragua, 1 from Guatemala and 1 from Belize.
4.Pinus oocarpa: Under the programme of International Provenance trial Programme,
seeds of P. oocarpa were received and seedlings have been raised for field planting. Total
8 provenances were received. These are – 3 from Nicaragua, 3 from Guatemala, 1 from
Honduras and 1 from Belize.
5.Albizia procera (Roxb.) Benth: Small quantity of seeds has been received from
Australian provenances. The seeds are being put in nursery trial (Das, 1982).
2.4. The Status of Alien or exotic Invasive plants in Bangladesh
Bangladesh has a long history of plant introduction. There are no detailed records
of exotic plants introduced in Bangladesh, except the more common plants and a few
cultivated ones. Perhaps the first widely introduced alien species in Bangladesh is Water
Hyacinth (Eichhornia crassipes), which was brought from Brazil during the British period.
British ladies were fond of its flowers and brought it over for decorative purposes. At that
time, nobody realized how vigorously this species could turn into an aquatic weed. Now it
has invaded almost all the wetlands of Bangladesh.
Many of the exotic plants are of economic benefit. Some of the very common fruit
trees, like litchi (Litchi chinensis), pineapple (Annas sativus), watermelon (Citrullus
lantus), coconut (Cocos nucifera) and guava (Psidium spp.) are also introduced, as are
most of the pulses and oil yielding plants. Many important vegetables, like cucurbits
(Cucurbita spp.), radish (Raphanus sativus), potato (Solanum tuberosum) and carrot
(Daucus carota) came from other countries and have been naturalized throughout the
country (Islam, 1991). In the 19th century, the British Foresters were mostly contributed to
the introduction of economically important forest trees (Tectona grandis, Paraserianthes
falcataria, Henea brassiliensis, Xylia kerrii, Swietenia macrophylla, S. mahagoni) from
20
almost all the continents. The same trend of introducing species continued and 20th century
and some Australian (Eucalyptus camaldulensis, Acacia auriculiformis, A mangium) and
South American species (Leucaena leucocephala, Pinus caribaea, P. oocarpa) are getting
preferences in plantation forestry. More than 100 tree species were tried in the forest
plantations of Bangladesh, of which only about 15 species are successful in plantation
programs (Hossain, 2004).
The main trees recommended for woodlot are Eucalyptus camaldulensis, Acacia
Mangium and Acacia auriculaeformis. In neighboring countries like India, Thailand
criticism against Eucalyptus is very strong and in India the angry villagers have reported
to have felled Eucalyptus from vast areas. The deliberate biasness of planting exotic
invasive already has changed the species rich natural forests to mono plantations of some
invasive species. Some of the species are aggressively occupying the natural ecosystems
and replacing the native vegetations.
The deliberate biasness of planting exotic invasive already has changed the species
rich natural forests to mono plantations of some invasive species. Some of the species are
aggressively occupying the natural ecosystems and replacing the native vegetations. The
ecologists, foresters, policy makers and environmentalists became concerned about the
loss of native biodiversity along with the deterioration of soil properties due to the
establishment of plantations with introduced species (Hossain, 2004). Scientific studies
show that indigenous species and even mono-culture of Sal found to have been more
productive and economic than the mono-culture of alien exotic species (Chowdhury ,
2003).
However, a good number of exotic plants are weedy in nature. Most of them were
first introduced as garden or ornamental plants before becoming established elsewhere.
Some of them are so well established that they are now the dominant plant and became
noxious weeds of forests and wastelands (Eupatorium odoratum, Mikenia cordata, Croton
spp. etc.). some are also considered noxious weeds of cultivated fields (Alternanthera,
Scoparia and Heliotropium spp.). Others are found in water (Eichhornia, Eleocharis and
Monocharia spp) (Ameen, 1999)
Uddin and Mohammad (2003) described a total of 113 plant species have been
identified as invasive those introduced here in Bangladesh by intentionally, accidentally,
purposely or by vectors. These are assigned into six categories including timber yielding,
fruits bearing, vegetable producing, flowers bearing, avenue tree, and weeds. Hossain and
21
Pasha (2001) prepared a short list of the alien invasive plants that are threatening the
ecosystem of Bangladesh which is given below:
Table 1: Some Alien exotics in Bangladesh, which have a detrimental impact in the
ecosystem:
Scientific Name Family Origin Impact on the ecosystem
Acacia
auriculiformis
Mimosaceae Australia Widelyplanted in afforestation
programs,butcontroversy over
pollen allergy!
Eucalyptus
camaldulensis
Myrtaceae Australia Promising growth
performance in experimental
plantations, but now ban due
to its controversial impact on
environment.
Leucaena
leucocephala
Mimosaceae Tropical
America
Occasionally cultivated; wild
in coastal areas; suppressed
the regeneration of other
species.
Acanthospermum
hispidum
Asteraceae South
America
Common weed of cultivated
fields
Cassia occidentalis
L.
Caesalpiniaceae Tropical
America
Common weed for wasteland
and road side
Cestrum diurnum L. Solanaceae Tropical
America
Weed of road side and rail
line
Lantana camara L. Verbanaceae Tropical
America
Common weed of hilly areas,
prevent regeneration of native
species
Ageratum
conyzoides L.
Asteraceae South
America
Common weed of waste and
cultivated field; aeroallergic
pollen species
Alternanthera
flocoidea L. R.Br.
Amaranthaceae Brazil Common weed of cultivated
and waste land
Atylosia
scarabaeoides
Benth.
Fabaceae Australia Common weed of wasteland
Eupatorium Asteraceae Central
South
Common weed of wasteland;
suppressed the regeneration of
22
odoratum L. America other species in plantation
programs
Commeline oblique
Buch-Ham.
Commelinaceae Java Frequent weed in wasteland
Convolvulus
arvensis L.
Convolvulaceae Europe Frequent weed of waste place
Croton
bonplandianum
Baill.
Euphorbiaceae South
America
Abundant weed of waste and
cultivated land
Eichormia crassipes
(C. Martius) Solms.
Pontederiaceae Tropical
America
Abundant aquatic weed;
aggressive growth inhabits
other aquatic flora
Evolvulus
nummularius L.
Convolvulaceae West India Common weed in cultivated
and open fields.
Hyptis suaveolens L.
Poit.
Lamiaceae Tropical
America
Common weed of hilly
regions
Ipomoea carnea
Jacq.
Convolvulaceae America Common weed of all habitat
Ludwigia
adscendens L.
Onagraceae Central
America
Common weeds in aquatic
and marshy habitat
Mikenia cordata
(Burm. f.) Robinson
Asteraceae Tropical
America
Abundant weed of forest and
wasteland; engulf other
economic crops by its
luxuriant growth
Mimosa pudica L. Mimosaceae South
America
Common weed of cultivated
and waste land
2.5. Alien Invasive Plant Species in the Global Context
2.5.1. Alien Invasive Plants in Europe: Europe appears to have less
invasive plant species but is the source of many invaders elsewhere (Weber and Peter,
2003). Fallopia japonica (Houtt.) Ronse Decr and F. sachalinensis (Schm.) Ronse Decr as
well as their hybrid F. x bohemica (Chrtek et Chrtkova) J. P. Bailey native to East-Asia
belong to the most dangerous invasive alien plants in Europe. Impatiens glandulifera,
Robinia pseudoacacia also causing harm to environment (Balogh and John, 2003).
23
In central Europe IAS are considered to be of lower ecological risk compared to
other regions. Of the 3383 established species of higher plants in Germany, About 30 of
the around 1000 neophyte plant species are considered to have negative impacts on native
biodiversity (Frank, 2004).
Environment obligation to eliminate invasive alien species in Slovakia applies
only to the seven most problematic plant species: Fallopia japonica, Fallopia x bohemica,
Fallopia sachalinensis, Heracleum mantegazzianum, Impatiens glangulifera, Solidago
canadensis and Solidago gigantean (Ema and Alzbeta, 2004).
Only four species orgroups present over 50% of all reported cases (Heracleum
mategazzianum, Fallopia spp, Solidago gigantea and S. canadensis). There are only a few
variations in the species mentioned. Prunus serotina and Rosa rugosa are especially
mentioned in the North of Germany, and Acer negando in the East
2.5.2. Alien Invasive Plant in North America: Invasives in the United
States included Canada thistle (Cirsium arvense), musk thistle (Carduus nutans), spotted
knapweed (Centaurea stoebe ssp. micranthos), diffuse knapweed (Centaurea diffusa),
yellow starthistle (Centaurea solstitialis), Russian knapweed (Acroptilon repens),
hawkweed (Hieracium sp), purple loosestrife (Lythrum salicaria), leafy spurge
(Euphorbia esula), Dalmatian toadflax (Linaria dalmatica), perennial pepperweed
(Lepidium latifolium), sericea lespedeza (Lespedeza cuneata), downy brome (Bromus
tectorum), medusahead (Taeniatherum caput-medusa), saltcedar (Tamarix spp.) and
tropical soda apple (Solanum viarum) (Duncan et al., 2003).
2.5.3. Invasive Alien species in South America (Brazil): Brazil is the
largest country in South America and it holds nearly 20% of the planet’s biodiversity, as
well as the largest percentage of freshwater species. Certain species which have a clear
history of invasion in other parts of the world and which have proved to become far more
of a problem than a solution, are currently being promoted in Brazil. The best example
may be Azadirachta indica (neem), a species widely invasive throughout West Africa,
recognized by farmers as a threat to economic sustainability. Neem is currently “the
species of the moment” in North Eastern Brazil, where the dry climate of the Caatinga is a
restriction to non-native species. Neem has been so successfully promoted that by now
nearly every rural property has a few trees planted for producing “natural herbicides” for
crops and medicinal substances.
24
Common invasive plant species are: Eragrostis plana, Ulexeuropaeus, Pinus
elliottii and Pinus taeda, especially in Southern grasslands; African grasses in the genus
Brachiaria all over the country and covering large extensions of central savannas;
Hedychium coronarium (white ginger), Artocarpus heterophyllus (jackfruit), Acacia
mangium, Elaeis guineensis (oil palm) in the Atlantic Forest; Hovenia dulcis (Japanese
cherry), Eriobotrya japonica (loquat), Melia azedarach (china berry), Ligustrum lucidum,
L. japonicum (tree privet) and Mangifera indica (mango) in riparian areas in the North
east. Species currently promoted for bio-diesel production are Ricinus communis (castor
bean) and Elaeis guineensis (oil palm), possibly characterizing the “ecological” production
of fuel as an environmental problem (Silvia, 2004).
2.5.4. Invasive Alien Species in South East Asia (SEA): Invasive alien
species (IAS) are causing billions of dollars worth of damage in Southeast Asia (SEA) as
well as causing displacement and, in some cases, extinction of hundreds of indigenous
species. Yet despite the magnitude of the damage, the prominence given to the control of
IAS in the Convention of Biological Diversity and the many international protocols and
initiatives to tackle this issue, almost no attention is paid to this threat in SEA; there are
few national programmes to combat established IAS or reduce the risk of more from
becoming introduced. Equally shocking is the fact that whilst some species have become
established accidentally, the bulk was deliberately introduced. The data sheets held on
SEA countries by the Global Invasive Species Programme database (Allan, 1936). for
instance fail to reflect the great extent or urgency of the problem. Hundreds of species are
involved - not less than ten species per country documented in the database.
In Malaysia, certain foreign species like itch grass (Rottboella cochinchinensis
Lour); water hyacinth (Eichhornia crassipes Martius); aquarium watermoss (Salving
molesta Mitchell) are officially listed by the country’s regulatory agencies as dangerous
exotic species as these are potential threats to agriculture (plants, crops, animals, live-
stock), non-cultivated ecological systems and human beings once these species enter and
establish themselves in the country.
In Philippines, Hagonoy weed (Chromolaena odorata) Large leaf lantana ihinese
creeper (Mikania micranth) Gmelina arborea, Acacia mangium, Eucalyptus
camaldulensis, Swiietenia macrophylla, Dipterocarpus grandiflorus, Leucaena
leucocephala, Toona ciliata, Water fern (Salvinia molesta), Water hyacinth (Eichormia
crassipes) etc. are doing great loss to ecosystem.
25
Of the 100 world’s worst IAS listed by the Invasive Species Specialist Groups
(ISSG), at least, 1 aquatic plant, 13 land plants, exists in Thailand. Some of the more
important IAS identified are water hyacinth (Eichornia crassipes) and giant water fern
(Salving molesta) among the water weeds, and gaint sensitive plant (Mimosa pigra), Siam
weed (Chromolaena odorata), mila-a-minute (Mikania micrantha), and Maui pamakani
(Ageratina adenophora) among the terrestrial weeds.
Some major culprits: Among the worst IAS in the ASEAN region are the: water
hyacinth (Eichhornia crassipes), pantropical weeds (Imperata cylindrica), Chinese
super-tree (Paulownia tomentosa) (Gregorio, 2002). Almost all lakes and fresh waterways
of the region are clogged with such species as water hyacinth (Eichhornia crassipes),
water lettuce (Pistia stratiotes), and yellow burhead (Limnocharis flava). These species
impede boat transport and fishing activities and also cause eutrophiation and loss of
productivity. Clearing these weeds annually involves great labour costs.
In addition to many pantropical weeds that have become very aggressive such as
Eupatorium (Chromolaena) odoratum, Mimosa pudica and grasses like Imperata
cylindrica, many ornamental plants are spreading out of control across the region. These
include. Lantana camara, Caesalpinia pulcherrima and climbing plants that can smother
the original vegetation such as Blue Trumpet Vine (Thunbergia grandiflora), Morning
glory (1pomea cornea), 1pomea cairica, Mile-aminute vine (Mikania micrantha),
Bougainvillea spectabilis and the edible Thai vine (Coccinea indica). Exotic coloniser
shrubs such as Piper aduncum, Mimosa pigra and prickly pear (Opunia monacontha) now
cover huge areas of the region (Mackinnon, 2002).
Foresters have consistently introduced exotic trees for plantations. There is often a
short-term advantage in planting a species in the place where its natural pests and diseases
are absent. In some cases such species spread out of control, displacing natural vegetation
and profoundly changing the natural ecology (Mackinnon, 2002). The Chinese super-tree
(Paulownia tomentosa) is listed as invasive in many countries. Several introduced conifers
have become established in the region and the spread of Australian Eucalyptus and Acacia
has a profound effect. Both Acacia auriculiformis and Acacia mangium grow well in SEA
(e.g. Bangladesh, India, Pakistan, Philippines, Thailand etc.) and spread naturally over
cleared and burned areas. These species create conditions of great flammability and
themselves thrive on regular fire episodes in lands where natural forest fires were unheard
of. As the 'haze' fires now burn annually in Borneo and Sumatra, so do these species
26
spread at the expense of native species and transform those islands into firescape monsoon
forests (Mackinnon, 2002).
2.6. 100 of the world’s worst invasive alien species:
(Listed by the Invasive Species Specialist Groups (ISSG) of IUCN (2003).
AQUATIC PLANT
Caulerpa seaweed (Caulerpa taxtfolia)
Common cord-grass (Spartina anglica)
Wakame seaweed (Undaria pinnatifida)
Water hyacinth (Eichhornia crassipes)
LAND PLANT
African tulip tree (Spathodea campanulata)
Black wattle (Acacia mearnsii)
Brazilian pepper tree (Schinus terebinthifolius)
Cogon grass (Imperata cylindrica)
Cluster pine (Pinus pinaster)
Erect pricklypear (Opuntia stricta)
Fire tree (Myrica faya)
Giant reed (Arundo donax)
Gorse (Ulex europaeus)
Hiptage (Hiptage benghalensis)
Japanese knotweed (Fallopia japonica)
Kahili ginger (Hedychium gardnerianum)
Koster’s curse (Clidemia hirta)
Kudzu (Pueraria lobata)
Lantana (Lantana camara)
Leafy spurge (Euphorbia esula)
Leucaena (Leucaena leucocephala)
Melaleuca (Melaleuca quinquenervia)
Mesquite (Prosopis glandulosa)
Miconia (Miconia calvescens)
Mile-a-minute weed (Mikania micrantha)
Mimosa (Mimosa pigra)
Privet (Ligustrum robustum)
Pumpwood (Cecropia peltata)
Purple loosestrife (Lythrum salicaria)
Quinine tree (Cinchona pubescens)
Shoebutton ardisia (Ardisia elliptica)
Siam weed (Chromolaena odorata)
Strawberry guava (Psidium cattleianum)
Tamarisk (Tamarix ramosissima)
Wedelia (Wedelia trilobata)
Yellow Himalayan raspberry (Rubus ellipticus)
MICRO-ORGANISM
Avian malaria (Plasmodium relictum)
Banana bunchy (Banana bunchy top virus)
27
Chestnut blight (Cryphoneotria parasitica)
Crayfish plague (Aphanomyces astaci)
Dutch elm disease (Ophiostoma ulmi)
Frog chytrid fungus (Batrachochytrium dendrobatidis)
Phytophthora root rot (Phytophthora cinnamomi)
Rinderpest virus (Rinderpest virus)
AQUATIC INVERTEBRATE
Chinese mitten crab (Eriocheir siensis)
Comb jelly (Mnemiopsis leidyi)
Golden apple snail (Pomacea canaliculata)
Green crab (Carcinus maenas)
Marine clam (Potamocorbula amurensis)
Mediterranean mussel (Mytilus galloprovincialis)
Northern Pacific seastar (Asterias amurensis)
Fishhook flea (Cercopagis pengoi)
Zebra mussel (Dreissena polymorpha)
LAND INVERTEBRATE
Argentine ant (Linepithema humile)
Asian longhorned beetle (Anoplophora)
Asian tiger mosquito (Aedes albopictus)
Bigheaded ant (Pheidole megacephala)
Common malaria mosquito (Anopheles quadrimaculatus)
Common wasp (Vespula vulgaris)
Crazy ant (Anoplolepis gracilipes)
Cypress aphid (Cinara cupressi)
Flatworm (Platydemus manokwari)
Formosan subterranean termite (Coptotermes formosanus shiraki)
Giant African snail (Achatina fulica)
Gypsy moth (Lymantria dispar)
Khapra beetle (Trogoderma granarium)
Little fire ant (Wasmannia auropunctata)
Red imported fire ant (Solenopsis invicta)
Rosy wolf snail (Euglandina rosea)
Sweet potato whitefly (Bemisia tabaci)
AMPHIBIAN
Bullfrog (Rana catesbeiana)
Cane toad (Bufo marinus)
Caribbean tree frog (Eleutherodactylus coqui)
FISH
Brown trout (Salmo trutta)
Carp (Cyprinus carpio)
Large-mouth bass (Micropterus salmoides)
Mozambique tilapia (Oreochromis mossambicus)
Nile perch (Lates niloticus)
Rainbow uout (Oncorhynchus mykiss)
Walking catfish (Clarias batrachus)
Western mosquito fish (Gambusia affinis)
28
BIRD
Indian myna bird (Acridotheres tristis)
Red-vented bulbul (Pycnonotus cater)
Starling (Sturnus vulgaris)
REPTILE
Brown tree snake (Boiga irregularis)
Red-eared slider (Trachemys scripta)
MAMMAL
Brushtail possum (Trichosurus vulpecula)
Domestic cat (Felis catus)
Goat (Capra hircus)
Grey squirrel (Sciurus carolinensis)
Macaque monkey (Macaca fascicularis)
Mouse (Mus musculus)
Nutria (Myocastor coypus)
Pig (Sus scrofa)
Rabbit (Oryctolagus cumiculus)
Red deer (Cervus elaphus)
Red fox (Vulpes vulpes)
Ship rat (Rattus rattus)
Small Indian mongoose (Herpestes javanicus)
Stoat (Mustela erminea)
Chapter 3: Of the attributes of
invasive plants
3.1. What are the negative impacts of invasive plants? /What
Threats Do Invasive Species Impose to ecosystem?
Biological invasions have caused severe unwanted impacts to local environments
and economics (Gollasch, 2004). Biological invasion has been becoming one of the most
serious problems in environmental protection and economic development (Zhang, 2004).
Invasive exotics rank second only to habitat destruction as a threat to rare and endangered
species. Yet competitive interactions between invasive and rare plants are often poorly
understood, with few data available to direct management (Thomson, 2003).
The significant impact of invasive alien species (IAS) to biodiversity has been
widely acknowledged (IUCN, 2000), yet little has been done to link IAS management with
29
biodiversity conservation, especially from an on ground perspective (Mahon 2000;
Downey 2003a). Reasons for this failure may be attributed to: (i) IAS management has not
been aligned with available information on alien species impacts to biodiversity (Mahon,
2000); (ii) information on the species directly impacted by each IAS is inadequate
(Downey 2004); (iii) the legislative requirements for alien species are listed under several
Acts, while others are not listed under any Acts (Downey 2003a); and (iv) the separate
historical management approaches of these two disciplines (Saunders et al. 1995; Downey
2003a).
The invasive alien species are mainly causing three different types of damage.
They are: 1) Damage to ecosystems, 2) Damage to human safety, 3) Damage to
agriculture, forestry and fisheries (Toshikazu, 2004).
The causes and impacts of increasing invasive species abundance are complex and
of interdisciplinary nature, involving ecological, social, and economic issues, and
interactions between them. The spatiotemporal distribution and composition of
biodiversity, and local forest resources in general, can be affected directly by invasive
species due to predation, herbivory, parasitism, pathogens, and competition (Poulsen, 2004).
Invasions by both native and exotic species potentially can threaten natural
communities. Invasive species contribute directly to the decline of threatened and
endangered plants and animals. Only habitat loss poses a greater threat. Invasive
species also exact heavy costs in lost productivity (Anon, 2003).
Second only to habitat destruction, invasive species pose the most significant threat
to native biodiversity worldwide. Invasive species have many devastating environmental
effects, including predation upon native species, unfettered population growth due to lack
of natural predators, and competition with indigenous species for scarce resources. Once
introduced, invasive species are difficult, if not impossible, to eradicate and may cause
extensive economic as well as environmental damage (Courtney and Perkins, 2004).
Biological invasion can permanently change ecosystems but methods for constraining
most invasions are unknown (Wilson, 2003). Species invasions are hypothesized to occur
in a series of steps, beginning with initial immigration of individuals to a new site.
Following an establishment period, the population begins to spread in an uncontrolled
manner and replace native species (Stanton et al., 2003).
Invasive species introduced by human being whether intentionally or
unintentionally create serious threats to biodiversity by replacement or predating of native
30
species. Invasive species also bring many threats to agriculture, fisheries and forestry and
help to spread communicable diseases (Makiko and Nobuo, 2004).Invasive and exotic
species may negatively affect a community by leading to decreases in population numbers,
increases in species extinctions, or altering ecosystem function (Mooney and Drake 1986;
Vitousek et al., 1996). The effects may be brought about by several factors, including
increased competition pressures, predation, disease, or amensalism (Martin and George, 2003).
Invasive species is an increasingly important disturbance factor throughout the
world’s humid tropical forests, affecting the spatial and temporal distribution and
composition of plants and animals. This change the availability of non-timber-forest
products to people who live, and depend upon resources found in, forests. Indigenous
people living in more interior parts of the forest away from developed infrastructure, and
hence often having few or no alternative income sources or options, will therefore tend to
be more sensitive to changes in the availability of local natural resources.
Although the number of invasive weeds is small, the costs are huge to the economy
and to the environment (Anon, 2003). Invasive weeds strive towards a monoculture,
choking out all desirable species (Vollmer and Jennifer, 2003). Invasive plants made
alteration of fundamental ecosystem structures and processes. Invasive plant species are
recognized to be a severe threat to environmental sustainability altering biogeochemical
cycles and disturbance regimes (Ustin et al., 2003). Mass invasions of alien plants (Plants
form the biological foundation of all terrestrial and aquatic communities) more or less
cause structural and functional changes in ecosystems, including alterations in nutrients
and/or structural conditions (Schmitiz et al., 1997). When an invasive plant species has
characteristics quantitatively different from those of species indigenous to the invaded
community, it has a great potential to alter ecosystem properties (Symstad, 2003). Many of
the invasive species have severely affected existing natural systems by displacing or
competing with native species and altering native habitats, or by damaging agro
ecosystems and other human resources (Andreasen, 2001). Particularly, changes in
dominant plant species may lead to the replacement of dominant plant consumers,
followed by their predators, and further cause a chain of changes in species compositions
at every trophic level, and thus disrupt food webs and other structural and functional
features of the ecosystem. In some cases, such ecosystem changes induced by an invasive
species can be perpetuated by a positive feedback cycle not dependent on the invader. In
31
these circumstances, eradication of the invasive species will not be sufficient to restore the
invaded community to its pre-invasion state (Symstad, 2003).
Even if the invasive species are pioneers dominating only early phases of the
vegetation succession were, the effects of the invasion may last long through persistent
soil seed bands. Invasive alien plant species, when once established in an ecosystem, may
cause irreversible changes by producing large seed sources above and/or under the soil
surface. (Thompson, 2000). Contemporary surface soils of various habitats, including
wetlands, woodlands, plantations, floodplains and farmlands have more or less
accumulated viable seeds of such alien plant species, even if the above-ground vegetation
contains no or few alien plant species. Flourishing invasive alien plants furnished with
strategies enhancing spatial and temporal dispersal of seeds inevitably cause alteration of
the earl stages of succession series. This is likely to be one of the most conspicuous
influences of plant invasions on ecosystem processes. Once a persistent soil seed bank of
an invasive species has been established, either natural or human disturbances will always
ring about the domination of the alien species, which will further replenish the soil seed
bank or enlarge the seed sources of the invasive species
Invasive species may negatively impact native species in any number of ways
including: competing with them, mating with them and decreasing genetic diversity,
introducing pathogens and parasites that sicken or kill them, and -disrupting available
nutrients. Art introduced species can change the look and makeup of an entire
system-changing species composition, decreasing rare species, and even changing or
degrading the normal functioning of the system. Maintaining intact natural systems is
important to ensure the continuation of ecosystem goods and services upon which humans
depend. Invasive plants can smother native vegetation or change the timing and severity of
fires, floods, and other disturbances. Introduced diseases and parasites can attack and
eliminate dominant native plant species.
In forestry and agricultural production, invasive plants outcompete crops for soil
and water resources, reduce crop quality, interfere with harvesting operations, and reduce
land values. The U.S. Department of Agriculture estimates the annual productivity loss of
64 crops due to exotic species at $7.4 billion. On rangelands, invasive plants, such as
Ageratum conyzoides, Eupatorium odoratum, crowd out more desirable and nutritious
forage, cause soil erosion, and poison some wildlife and livestock species. In natural areas,
nonnative plants, such as Eucalyptus camaldulensis reduce habitat for native and
32
endangered species, create fire hazards and interfere with recreational activities. Aquatic
invasive species, such as the Eichhornia crassipes clogs lakes and waterways and
adversely affect fisheries, public water supplies, irrigation, water treatment systems,
recreational activities, and shipping. In 'the ocean, nonnative marine organisms are now
impacting the availability of energy (Khanna, 2003)
Throughout the humid tropics, highest concentrations of native and endemic
biodiversity tend to occur in the interior of forests, which also tend to be critical for the
livelihoods of many indigenous peoples. Invasive species change the utilization (such as
extraction) patterns of local forest resources. Finally, there may be a feedback impact of
the changed spatiotemporal utilization patterns on the distribution and composition of the
natural resources (Poulsen, 2004).
Invasive alien species represent a major disruption for all biotic systems including
terrestrial and aquatic, managed and wild. Invaders can have enormous economic and
human health impacts as well as degrading many system properties that society values,
including biodiversity. Invasive species can devalue the ecosystem services upon which
we all depend in all nations, developed and developing (Harold, 2001).
Invasive species cause ecological damage by outcompeting native species,
reducing biological diversity, and changing ecosystem functions such as flood and fire
regimes or nutrient cycling. The Asian vine Mikania quickly climbs over trees and shrubs
and even kill them by strangling and shading. Invasive species also have major economic
consequences, ranging from the loss of economically valuable species to the costs of
controlling or managing infestations on public lands.
3.1.1. Harold (2001) summarized negative impacts of invasive plants as follows:
Invasive can disrupt community and ecosystem processes
Invasives are causing large economic losses and are threats to human health and
welfare and to sustainable development
Invasive alien species have altered evolutionary trajectories
Losses to agriculture, forestry and fishery
Increased maintenance costs for roadways
Damage to waterways and rivers
33
Alien species that are health hazards
Endangerment of native species.
3.2. The scale of economic losses by invasive plants
The spread of invasive alien species may have an economic or ecological impact.
For example, In total, the enumerated costs for these species and add up to an average
annual expenditure of € 167 million in Germany, and are estimated to cost $ 137 billion
annually in losses to agriculture, forestry, fisheries and the maintenance of open
waterways in the United States alone (Anon, 2003). These losses are seen in production
losses in agriculture, forestry, and fishery, and costly eradication programmes to eliminate
undesirable species (Money and Hobbs, 2000). Similar costing exercises are almost totally
absent in the South East Asian(SEA) region. But given the size of the region, the total
human population and the greater direct dependence of the population on biodiversity and
primary production systems, it is clear that the damage to ecosystems and economies must
also be counted in billions of U.S dollars per annum (Mackinnon, 2002). But the economic
or ecological loss of invasive alien species are not quantified in Bangladesh.
3.3. The traits of successful invaders
Invasive species often exhibit certain characteristics: they spread aggressively,
reproduce quickly, have short juvenile periods, tolerate a wide range of climatic conditions
and habitats, compete efficiently against other species, and thrive in disturbed areas
(Rahel, 2002). These alien invasive plants are able to reproduce rapidly because the
animals and diseases that keep them in check in their home ranges are missing (Drees,
2003). For example, Teak (Tectona grandis) trees from Myanmar threaten to replace the
ground vegetation. When the populations of native plants are reduced, the animals that
depend upon them lack the food and shelter needed for survival (Drees, 2003). Species
with fast reproductive rates and good dispersal ability are very dangerous. Such species
include many grasses, climbers, coloniser shrubs and trees with wind dispersed seeds.
Introduction of close relatives of indigenous species is highly prone to result in genetic
pollution of the local form (Mackinnon, 2002).
34
3.3.1. We are facing a great challenge of the invasives because:
Invaders are self replicating
Evolve response to control efforts Invasive, invasive plants and animals in
particular, can quickly
Lag times are common before adverse effects are seen
Invaders alter and respond to community interactions in complex ways
Movement of potential invasive material is increasing
Global changes mostly favor invasives
Informations base inadequate for risk assessment
Inadequate public awareness of the problem (Harold, 2001).
3.4. What makes a community invisible?
Understanding plant community susceptibility to invasion is important to
implement invasive plant management. Determining susceptibility may be achieved
through study of the invasive plant species distribution and growth along environmental
gradients (Prather et al., 2003). The notion of assembly rules lies at the heart of predictive
community ecology and the prediction of successful invasion of communities by non-
native species is an important goal for forest managers. Neutral (null) models of
community assembly, as well as drift models (Hubbell) suggest that all communities
should be equally invasible and that good invaders are mainly good dispersers. Niche-
based assembly theory would suggest another set of answers. First, invasible communities
(i.e. “open” communities) should be those that are constrained by weak assembly rules
(e.g. places of maximum species density) or they are communities that do not conform
closely to the local assembly rules (e.g. places that are chronically disturbed or places
where the natural processes have been altered for a protracted period of time). Second,
species that have good dispersal ability and establishment ability tend to be good invaders,
but these species are only rarely labeled “invasive” because they rarely dominate
communities. In order to dominate. invasive species must also have high rates of resource
acquisition and have strong competitive effects on neighbors. Invasive species with very
high competitive ability may simply be a replacement for a native dominant species and
35
this may make the question of community invisibility moot. The most difficult question
for understanding species invasiveness is how dispersal, establishment, and competitive
effect are enhanced upon introduction. Escape from co-evolved microbial and fungal
pathogens as well as parasites and predators, must be critical for prolonged invasiveness
(Weiher, 2004).
Examining patterns of invasion allows us to make some generaIisations. Some
ecosystems are more vulnerable than others. Freshwater systems, Small Island, areas with
high number of local endemic species and areas undergoing major landcover
transformation are particularly vulnerable and need special vigilance and protection. A
logged forest is more prone to invasion than a primary forest (Mackinnon, 2002)
Invasions of alien species are also made worse by many of the other pressures
facing the planet — habitat degradation, climate change, urban sprawl, and the impact of
globalization and trade on natural resources and biodiversity, both wild and domesticated
3.5. Process of biological invasion of the ecosystem
Biological invasion is an irreversible process. Contaminated chemical in the
environment will be decomposed after several years, however invaded organisms
reproduce themselves and persist almost for ever. New invading organisms will change the
nature of forests, rivers and lakes in the future.
The process of biological invasion is complicated, involving many interacting
factors related to the invader, the vector, and the source and recipient ecosystems.
However, an invasion can be conveniently broken down into three phases: arrival,
establishment, and ecological integration. A successful invader, however, must be
accomplished at each. Examination of the worldwide invasion of Musculista senhousia
also emphasizes several topics of general importance to invasion biology. First, prolonged
time lags might exist at each stage of the invasion process, making prediction difficult.
Second, the factors that make ecosystems vulnerable to invasion are typically difficult
identify, and are often confounded with the supply of potential invaders to the system.
However, experimental approaches can offer some insight into the problem of invisibility.
Third, some of the most profound effects of invaders result from the physical modification
of habitats, and certain classes of these impacts may in fact have a relatively high degree
of predictability (Crooks, 2004).
36
3.6. Mechanisms of habitat degradation due to invaders
Harold (2001) presented the mechanisms of habitat degradation due to invaders.
For most invasive alien species it is not difficult to demonstrate negative impact. By
illustrating the great number of ways in which an invasive alien species can threaten the
goods and services provided by natural systems upon which society depends. This list
includes species that are:
Fire stimulators and cycle disruptors;
Water depleters;
Disease causers;
Crop decimators;
Forest destroyers;
Fisheries disruptors;
Impeders of navigation;
Clogger of water works;
Destroyer of homes and gardens;
Grazing land destroyers, Species eliminators;
Noise polluters and Modifiers of evolution
3.7. Invasive Weeds
We are all affected by weeds. Weeds are simply plants that grow where they are
not wanted. Invasive weeds are plants that must be managed intensively or they will
overgrow crops or completely take over natural ecosystems. Weeds are invasive plants
that degrade our natural areas, reduce the sustainability of our agricultural industries and
affect the health of people and animals. Plants provide us with food and fibre, decorate our
yards and gardens, and provide habitat for wildlife. But when plants grow where they are
not wanted, we call them weeds. To homeowners, weeds may be unwanted plants in lawns
or gardens. To farmers, weeds are plants that interfere with raising crops or livestock. To
37
biologists who manage natural areas, weeds are plants that interfere with the functions of
natural communities.
Natural area weeds are often exotic plant species (plants whose natural range does
not include Bangladesh and were brought here from outside the country that have become
naturalized (capable of reproducing outside of cultivation). Invasive exotic plants are
weeds that alter the functions and value of natural areas by displacing native species and
disrupting natural processes such as fire and water flow (Rahel, 2002). Some invasive
weeds like Mimosa pudica Eupatorium odoratum L., Lantana camara L., Croton
bonplandianum Baill., Atylosia scarabaeoides Benth., Ludwigia adscendens (L.) ,Mikenia
cordata, Alternanthera flocoidea etc. are creating major problem to our forests and
wastelands. Foresters must remove invasive exotic plants species to maintain the integrity
on natural areas:
3.7.1. Weeds can:
Cause allergies and sickness.
Poison and injure domestic pets and livestock.
Increase the cost of food.
Block and pollute waterways, affecting the quality of our drinking water and
increasing the cost of its management.
Reduce the productivity of crops and pastures.
Increase the risk of herbicide resistance in agriculture.
Increase the risk of bushfire.
Harbour feral animals and diseases.
Reduce biodiversity and contribute to local extinctions of native plants and
animals.
Spoil our natural landscapes and reduce their appeal to tourists.
Affect our recreational use of natural areas
3.7.2. Invasive weeds share several common traits:
o Grow fast and spread across large areas,
38
o Reproduce several ways including seeds, buds, fragments, and shoots from
roots,
o Survive in many different temperature, light, water and soil conditions,
o Difficult to control, and nearly impossible to eradicate (Anon, 2003). Pasture
grass species are a major source of plant invaders in many parts of the world
(Heywood, 1989; Lonsdale, 1994). It is not surprising, therefore, that these
plants, which were chosen because of their rapid growth, adaptation to sunlit
environments, and tenacity, have also shown markedly high invasiveness
(Washitani, 2002a; Myers & Bazely, 2003).
3.8. Invasive Aquatic plant problem
Plants grow in a variety of different forms. Some are emergent plants, some are
floating plants and others submersed plants. Aquatic plants that evolve or develop in one
geographic area or region are said to be native aquatic plant to that area. Native aquatic
plants are a natural part of lakes, rivers, and wetlands and play several important roles in
maintaining healthy aquatic ecosystems. Native aquatic plants seldom cause problems
because they have adapted to one another and their environments over millions of year.
Invasion by non-native species is a serious threat to the conservation of freshwater
ecosystems (Fuller et al., 1999; Rahel, 2002). Aquatic plants that are moved, either on
purpose or by accident, to other areas are called non-native, non-indigenous, exotic or
alien aquatic plants. People move plants from one location to another for many reasons
including food for themselves and for livestock, or because of the plant’s unusual or
beautiful appearance (Anon, 2003).
Many different insects and diseases evolved with and control native plants,
keeping them from becoming problems. The delicate balance among native plants is often
destroyed when people introduce fast growing invasive aquatic weeds from other areas
without the controls that keep them in check in their home waters.
3.8.1. Native aquatic plant benefits include:
o Shelter for fish, birds and other wildlife,
o Habitat for insects that are eaten by fish,
o Protect shorelines from erosion,
39
o Clean some pollution from water.
3.8.2. On the other hand Invasive aquatic weeds:
o Destroy fish and wildlife habitat,
o Block navigation and flood control,
o Stop recreation like swimming and fishing,
o Reduce tourism and properly values,
o Clog drinking, irrigation and hydroelectric power and pipes
(Anon, 2003).
Biological invasion into aquatic systems causes, in some occasions, drastic
changes and serious impacts to native ecosystems. Oceanic islands are in general much
more susceptible to invasions than continents (Philip and Lloyd, 2001). Dispersal vectors
of aquatic invasions are shipping (ballast water and hull fouling), intentional releases for
fisheries, aquaculture and recreational fishing, and uninterntional introduction with the
target species. The new convention for the control and management of ballast water and
sediment was adopted at the diplomatic conference of International Maritime Organization
(IMO) in February 2004, and legislative management of introduced marine organisms is
now being developed in each ratifying country. However, methods for the risk assessment
and management for other vectors have never been developed effectively (Keiji and
Katsuki, 2004).
In comparison with unvegetated systems, the early stage of non-indigenous aquatic
weed infestation in lakes and reservoirs appears to provide some environmental or
ecological benefits. Unfortunately, short-term habitat and water quality gains are often
followed by long-term management as well as ecological problems (Smart et al., 2003).
The aquatic environment provides unique opportunities for invasive species and
challenges for resource managers. The combination of an open niche and the usual
presence of numerous nonindigenous species in the watershed often result in serious
management problems when nonindigenous aquatic plants invade (Howard, 2003).
Unfortunately, it is often difficult to establish aquatic plants in unvegetated
systems. Fluctuating water levels, high levels of nutrients and turbidity, and the presence
of omnivores such as common carp and turtles can be serious impediments to
establishment of diverse native plant communities (Smart, 2003).
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3.9. Invasive Alien species in wetlands in Bangladesh
Wetlands in Bangladesh are increasingly being recognized as ecosystems of
extreme importance to man and biodiversity. People derive many benefits from the goods
and services provided by wetlands while wetland systems are the “homes” of many
species of animals and plants and their habitats.
Wetlands, as well as lakes and rivers, however, has been impacted by alien
invasive species that specialize on aquatic (and semi-aquatic) systems and which cause
damage to their human benefits and their biodiversity. These are species that come from
“outside” and which arrive without their native controls – such as their own competitors,
predators, parasites and pathogens. They are species which grow fast, spread quickly and
cause all manner of problems in their “new” ecosystems.
The damage caused by alien invasive species to Bangladesh wetlands runs into the
billions of dollars annually – but hard data is hard to acquire as the impacts of these
species are only just being realized. Most well-known would be the Water Hyacinth -
sometimes called “the world’s worst water weed” – which has inflicted wetlands, lakes,
rivers hydro-schemes, irrigation and water supply systems, fisheries and human welfare -
not to mention its effects on Bangladesh’s aquatic biodiversity. There are the huge costs of
control, to manage the invasive species and then to try restoring the affected ecosystems to
their previous condition.
Bangladesh’s wetlands and then the threats they pose in existing and future
invasions. It is also necessary to provide some information on their identify, possibilities
for control and sources of available information and technical assistance. Wetland
invaders can rarely be eradicated, but they can usually be controlled if efforts to prevent
their arrival have failed and if they have become established. Control is always expensive
and time-consuming but can result in lasting ecosystem integrity.
3.10. Exotic invasive plants in the hill forest of Bangladesh
Exotic invasive plant species are threatening world forests through the alteration
of plant community composition. As a result, forest regeneration and understory diversity
may be restricted or greatly reduced (Ross and Joan ,2003). Bangladesh, like many other
41
countries have a long history of plant introduction from different geographic areas of the
world. A good number exotic plant became weedly in nature. Most of them were first
introduced as garden or ornamental plants and mainly brought by settlers, invaders,
seamen and traders. Some of them are so well established that they are now the dominant
plant and became noxious weeds of forests and wastelands. Some of the species, namely
Ageratum conyzoides, Eupatorium odoratum, Hyptis suaveolensis, Lantana camara and
Mikenia cordata have luxuriant growth and suppressed the regeneration and growth of
other native valuable species. This results low productivity and loss of native floral
diversity of the hill forests areas of the country. Infestation of these aggressive plants is
expanding and posed threat to natural habitats and plantation forests. The possible
suggestions to prevent the impacts of invasive plant species are enhancing awareness
among the planters, growers and publics; development of a database on invasive species,
quantify the abundance of the species, development of an environmentally sound
eradication methods and also introducing the necessary quarantine, legislation and
regulations on the spreads of the invasive plants (Hossain, 2003).
3.11. invasive plants in Sunderbans mangrove forest
Sunderbans is the world’s largest continuous single block of mangrove forest. Its
rich blend of flora, fauna and vivid ecosystem function make it a unique ecosystem in the
world. Over the few years the forest is under severe human disturbance. These are
basically changed in the salinity regime, introduction of terrestrial species in the
mangroves, construction of dams and illicit feling. All these leads introduction of few
alien species at the same time several native species to become invasive. Among the exotic
species Echhornia crassipes, Eupatorium odoratum, Micania scandens, Syzygium
fruticosum are causing enormous damage to the Sunderbans ecosystem. On the other hand,
Derris trifoliate, Acrosticum aureum, though known widely as mangrove associates, now
affecting the ecosystem badly. Initially these species does not seems problematic but as
human disturbance increase, so as their rate of invasion also increase. A study was
conducted through a combination of systematic and purposive sampling to identify their
impact on the Sunderbans. It was appeared that these species affect the Sunderbans
ecosystem from very initial stage of ecosystem dynamics. Echhornia crassipes,
Acrosticum aureum impedes the mangrove propagule restricting propagule movement also
impedes mangroves normal expansion. Derris trifoliate twist the host tree. Syzygium
42
fruticosum initially was limited only within open raised area of Sunderbans but the species
has coped to stay with the saline environment and densely colonizes inside the forest floor.
In newly formed land these species with their profuse regeneration colonizes and restricts
mangrove settlements. The ecological associations of these species were also identified.
Monitoring of rate of invasion with abundance was suggested for determination of
ecosystem health hazards caused by invasive plants (Biswas, 2003).
3.12. Invasive Alien Plant Species in Riparian Areas
Invasion by alien plants constitutes one of the most serious threats to biodiversity
through the displacement of native plants (Coblentz, 1990; Vitousek et al., 1996;
Simberloff et al., 1997). Owing to frequent disturbance, riparian areas are particularly
vulnerable to invasion by alien vascular plants (Stohlgren et al., 1998; Hood & Naiman,
2000). Riparian ecosystems are important for maintaining local biodiversity because of
their environmental uniqueness. Riparian vegetation is established under the influences of
unique environmental conditions such as flooding disturbance regimes. The vegetation
thus established in turn influences the dynamics of water flow and the movement of
sediments and nutrients into rivers (e. g., Peterjohn & Correll, 1984; Decamps, 1993) and
it features high species diversity (Gould & Walker, 1997). One explanation for the high
species diversity of riparian ecosystems is that floods periodically destroy vegetation
cover, create bare ground for recolonization, and produce a shifting mosaic of vegetation
patterns and landforms that create diverse habitats (Hood & Naiman, 2000). In addition,
riparian areas serve as landscape corridors facilitating the dispersal of propagules by water
flow, which is indispensable to range expansion and maintenance of metapopulation
dynamics of riparian plants. (Campbell et al., 2002).
The same factors that maintain a diversity of plant species may equally increase
vulnerability to invasion by alien plants in riparian areas (Washitani, 2000). Disturbances
to create unoccupied sites and dispersal of propagules by water flow in riparian areas may
promote invasions by alien plant species for some of the same reasons that they sustain
native species diversity.
The availability of suitable habitats and the supply of propagules of alien
agricultural weeds and revegetation species in riparian areas may account for their
invasiveness. As we already mentioned, riparian habitats are subject to increase the
43
creation of bare areas suitable for colonization by these species. (Pollock et al., 1998).
Although the terrestrial habitats of riparian areas are diverse, the aquatic environment is
relatively uniform (Ashton & Mitchell, 1989). Accordingly, many species, particularly
submerged and floating plants, are widely distributed throughout the world. This holds for
alien aquatic plant species such as water hyacinth (Eichhornia crassipes (Mart.) water
lettuce (Pistia stratiotes L.) Red water fern (Azolla filiculoides) water fern (Salvinia
molesta) etc. (Committee for Investigating the Effects of and Countermeasures against
riparian exotic Species, 2003).
In riparian areas, propagule supply from adjacent invaded habitats (e.g., Pastures,
revegetated levees, agricultural fields, roadsides) is likely to contribute significantly to the
further invasion of alien plants. More than half of riparian invaders are agricultural weeds,
so appropriate management of weeds in agricultural areas could be effective in restricting
the introduction of new invaders to riparian areas. Most weeds of agricultural systems
have competitive ruderal adaptations that are suitable for taking over disturbed habitats
(Grime, 1977). Consequently, environments favoring these species include sparse
meadows that are subject to seasonal disturbances such as floods, as well as roadsides and
agricultural fields. These characteristics of agricultural weeds make them potential
invaders of riparian habitats. Therefore, alien plant management plans are needed for both
natural habitats and agricultural areas. In addition, the use of alien pasture species for the
purpose of revegegetation or control of soil erosion should be restrained, firstly to
conserve biodiversity and native ecosystems, but also to avoid provoking grass pollen
allergies. Identifying the characteristics of invasive alien species is the first step in
developing management strategies for riparian areas and will be a stepping-stone to further
detailed studies on invasion biology and conservation ecology.
3.13. Atmospheric invasion by pollens of non-native plants
Most research on plant invasion impacts focus on the effects of weeds on crops or
the effect of well established introduced species on community structure or ecosystem
functioning. However, quantitative information regarding the risk they pose for human
health is anecdotal.
One of such risks can be the allergenic nature of the pollen of some introduced
plants. The pollen spectrum contains 95 pollen taxa. Even though pollen from native taxa
44
is more diverse than pollen from non-native taxa, that it is present in the atmosphere for a
longer period of time. Most of the airborne pollen is allergenic. Non-native pollen has a
larger proportion of allergenic pollen than native pollen. Most of this non-native pollen is
allergenic. The presence of non-native airborne pollen enlarges the period of allergenic
symptoms susceptibility (Vila and Jordina, 2003).
Invasive species like Melaleuca in limited plantation in Bangladesh is blamed to
spread pollen allergy.
3.14. Ways of spread of invasive plants or the vectors of
invasives
Today, many species, either intentionally or accidentally, have been introduced
into sites that were not their original habitats (Primack and Kobori, 1997). Some
nonnative species have been deliberately introduced in Bangladesh. More than 300 exotic
species are supposed to either wildly growing or cultivated as an economic crop in
Bangladesh. Of them the herbaceous and lianas are the dominant exotics followed by trees
and shrubs.
Introduction of invasive alien plants may be intentional or unintentional.
"Intentional introduction" means an introduction made deliberately by humans, involving
the purposeful movement of a species outside of its natural range and dispersal potential
(Such introductions may be authorized or unauthorized). Intentional introduction may be
by Institutions (FD, BFRI etc.) setters, invaders, seamen and traders. Most of the plants
have been brought by Institutions (FD, BFRI etc.) settlers, invaders, seamen and traders.
"Unintentional introduction" means an unintended introduction made as a result of a
species utilizing humans or human delivery systems as vectors for dispersal outside its
natural range. Unintentional introduction may follow natural process.
The distributions of many species are restricted by factors such as climate,
environmental conditions, and geographic limitations. However, humankind has
considerably changed the process of natural evolution by relocating countless species of
plants. Invasive species can move among and across continents in a number of ways,
Identifying and understanding those pathways can suggest ways to slow or stop the
movement (Reichard S. H. 2003).
45
Increased and more efficient worldwide trade, travel, and transport is greatly
increasing the number and diversity of harmful organisms being moved around the world,
as well as the rate at which they are moving. Expanding global trade in agriculture,
forestry, fisheries and other industries that depend on raw materials has allowed the
transport of species to various parts of the world. This has provided wider access to the
world’s biodiversity, thus providing better opportunities for economic and social
enrichment. One of the most significant impacts of the globalisation of trade has been the
establishment of non- native species that have wreaked havoc on local ecosystems.
Imported agricultural materials are principal source of exotic weed seeds (Makiko and
Nobuo, 2004).
Human activities have increased the wholesale movement, either accidental or
deliberate, of many species of plants and animals from one region of the planet to another.
Human activities have improved the odds for many non-indigenous species. A rapidly
increasing human population has led to greater land disturbance, which favors the spread
of invasive species. Increased demands for food and fiber and overuse of public lands for
recreation and commercial purposes have also contributed to nonnative invasions.
Invading species have often been able to establish populations in the new regions, many
spreading successfully over large areas or achieving high abundances (Andreasen, 2001).
Good invaders are mainly good dispersers (Weiher, 2004).
Some agricultural crops and trees have escaped plantations and became pests and
the importation of agricultural and forestry products have brought assorted pest species
and diseases into new areas. Nonnative ornamental plants are used in landscaping around
homes and institutions. Many have moved into natural landscapes, some with significant
ecological or economic impacts.
The aquarium trade is the source of a large number of aquatic species accidentally
or Intentionally released into waterways. Aquaculture has also increased the spread of fish
and other aquatic species and associated diseases.
The expansion of international distribution associated with globalization of
economy has caused increase of biological invasion (Koich et al., 2004). At the same time,
human- driven changes in land use and climate are rendering some habitats more
susceptible to invasion.
46
Thousands of species of marine organisms were and are moved around the world
on ship bottoms, and hundreds more have been moved globally by the wholesale transfer
of edible oysters, for "replanting."
Ships’ ballast water is known as one of the primary vectors of un-intentional
species introductions in aquatic ecosystems. Shipping, i.e. ballast water and hull fouling, is
the most important vector of un-intentional species introductions in aquatic ecosystems
(Gollasch, 2004). It is estimated that more than 10,000 marine species each day may hitch
rides around the globe in the ballast water of cargo ships. When ships unload their cargo,
they often fill their ballast tanks with water to provide balance for their return journey. In
addition to water, marry aquatic organisms are sucked into these tanks and given transport.
A ship will then empty its ballast tank (and various aquatic stowaways) at the next port it
takes on cargo. Many invasive species have become introduced into new areas this way.
Flooding can also transport nonnative aquatic and marsh species to row regions.
Species invasions are one of the top four anthropogenic threats of the worlds oceans
(Gollasch, 2004).
Fragmentation of habitat may be important factor to determine spread of invasive
plants. Habitats of plants are usually fragmented to some extent. Sparse habitat patch
density may cause delay in spatial spread of invading plants, and sometimes prevent
invasion if habitat patch density is low enough (Koike, 2003). Knowledge of the
ecological constraints on an invading species is essential for predicting its potential
distribution and can reinforce the justification for removing isolated populations beyond
the main invasion front (Pattison and Richard, 2003).
3.15. Invasive Alien Plants may not show signs of invasion
through years
The impacts on biodiversity and ecosystem functioning, caused by invasive alien
species (IAS), are often more surprising or more complex than the impacts of agricultural
weeds, for example. Indirect impacts on native species can also be surprising. An
established alien species may be “dormant” and show no signs of being invasive for years
or decades, before rapidly expanding in range and abundance and becoming invasive
(Crooks and Soule 1999, Mack et al., 2000). Triggers can include changes in ecological
conditions- human disturbance, or even natural disturbances like hurricanes. Another
47
reason why it may take time for invasiveness to show up is that it may require cumulative
interactions with other alien species. Not only can interactions with other alien species
trigger invasiveness in previously non-invasive species, it can also create a risk that an
already invasive species might become even more invasive (McNeely et al., 2001).
Of course, many if not most, alien species will not become invasive. But given that
the impacts from alien species can be direct, indirect, cumulative and/or complex,
unexpected, surprising and counter-intuitive and that they often only show after
considerable lag times, any alien species must be considered “guilty” until proven
“innocent”, where the risk of becoming invasive is concerned. This has also been
expressed by IUCN and GISP respectively as: “In the context of alien species, unless there
is a reasonable likelihood that an introduction will be harmless, it should be treated as
likely to be harmful” (IUCN, 2000). Or every alien species needs to be managed as if it is
potentially invasive, until convincing evidence indicates that it presents no such threat”
(McNeely et al., 2001)
3.16. Attributes of the invasiveness (invasibility) of a non-native plant
species
To determine which characteristics contribute to the invasiveness of a species and to
the invisibility of an ecosystem, Milbau and Ivan (2003) conducted experiments with
simulated invasion in synthesized grassland communities. The results suggested that
species characteristics would largely determine the possible extent of an invasion event
(number of seedlings), while the final success of the individual invaders (growth and
survival) is determined by both species and ecosystem characteristics. They therefore
argued that invasion success depends on a match between invader characteristics and
habitat, and that life-history traits themselves are not a significant predictor. Their second
experiment showed that on a small scale invasion resistance was higher in more diverse
communities. Both invader and leaf length decreased with increasing species number,
while invader germination was unaffected. Differences in invisibility could be partly
explained by the increasing biomass of the plants surrounding the invaders and the
decreasing amount of photosynthetically active radiation (PAR) reaching the invader
seedlings in the more diverse communities.
48
Weber and Nicole (2003) forwarded a key question towards predicting the invasion
ability of plant species is, whether invasive species have characters that distinguish them
from closely related non-invasive species. Their experiment demonstrated that plant size is
the most pronounced difference between invasive and non-invasive congeners, and that
relative growth rates as well as amount of phenotypic plasticity are not necessarily
correlated to invasion success.
Successful invasion may depend on the capacity of a species to adapt to a spatially
varying environment. Local adaptation is usually considered to result from the interplay
between natural selection (which increases locally favoured genes) and gene flow (which
introduces foreign maladapted genes) (Alleaume -Benharira et al., 2003). A nitrogen-
fixing species can increase nitrogen levels, change nitrogen-cycling in the ecosystem and
potentially facilitate the further invasion of other exotic species (Van Riper and Jennifer,
2003).
3.17. Biological invasion and ecological resistance
The term, ecological resistance was first coined by Elton in the 1950’s to describe
those processes or system properties that reduced the likelihood of an invader establishing
and having an impact in a community. Over the following decades, ecological theory
developed primarily around the assumption that competition was the key structuring force
in natural communities and was the likely source of resistance to invasion for species
introduced to communities where they were previously absent. However quantitative
evaluations of resistance have shown that it can result from competition,
predation/herbivory or from abiotic factors, these factors vary over space and time and that
resistance is therefore probabilistic and variable (D’antonio, 2003).
3.18. Effect of climate change on the success of invasive plant
species
Biological invasions and climate change are two of the greatest environmental
challenges that we face today. Individually, each of these elements of global change is the
subject of much research. However, studies of invasion biology have rarely considered
climate change, and vice versa. Such research is important because biological invasions
can have strong effects on the structure and function of ecosystems that are responding to
49
a changing climate and on the services provided by those ecosystems; climate change is
also altering the context in which potentially invasive species succeed or fail. There are a
variety of reasons why climate change might be expected to increase the success of
biological invaders. For instance, a rapidly changing climate might favor species that can
extend their ranges quickly or that can tolerate a wide range of climatic conditions. Both
of these traits are shared by many invasive plant species. Few studies have focused on the
general mechanisms through which climate change could benefit invasive species. How
much climate change will benefit invasive species remains difficult to predict and will
always be difficult to measure. Hopefully, results from future research will teach us how
to minimize the benefits that invasive species might draw from a changing climate (Dukes,
2003).
3.19. Restoration of soils altered by exotic plant invasions
The potential for restoring soils affected by exotic plant invasions is not well
known, in part because the kinds of changes that occur following invasions are not yet
well characterized. Ehrenfeld (2003) described the changes that have been documented in
upland soils, following invasions of Japanese stilt grass (Microstegium vimineum). Include
the loss of the organic horizon, an increase in soil pH, altered patterns of nitrogen cycling
and availability and changes in microbial community structure. These results suggest that
the restoration of forest soils may require reductions in both pH and N availability,
alterations that are opposite to the most common manipulations in soil restoration of
degraded sites. Methods for such soil manipulations are not well developed, and so there
are few well-known tools to accomplish such changes. The manipulations that have been
used to decrease soil pH and N availability are likely to be effective only over short time-
periods, suggesting that long-term restoration requires identification of the mechanistic
link that allows an exotic to cause the alteration to begin with. Long-term restoration
strategies should include the introduction or re-introduction of native species whose effect
on the target soil process is opposite to that caused by the invasive species. Methods for
manipulating the soil biota to produce long-term, stable changes in both the microbiota
and the fauna are particularly poorly known (Ehrenfeld, 2003).
50
3.20. Hybridization and evolution of invasiveness in plants
Ellstrand et al., (2003) presented and review a remarkable number of cases in
which hybridization occurred prior to the appearance of the emergence of successful
invasive populations. Hybridization between species or between disparate source
populations may serve as a stimulus for the evolution of invasiveness. Progeny with a
history of hybridization may enjoy one or more potential genetic benefits relative to their
progenitors. The observed lag times and multiple introductions that seem a prerequisite for
certain species to evolve invasiveness may be a correlate of the time necessary for
previously isolated populations to come into contact and for hybridization to occur.
3.21.Biological invasions in protected areas
Invasive species are largely seen as a problem by virtue of their devastating effects
in high conservation value areas (Akerson, 2003). Protected areas (PAs) form the last
remnants of less degraded landscapes and ecosystems around the world. Invasive alien
species (IAS) are frequently cultivated and intentionally dispersed in protected areas for a
variety of reasons. Considering the formally protected areas such as national parks, which
are more commonly assured of legal protection from habitat fragmentation, invasion may
become the greatest threat to many protected areas.
Macdonald et al (1989) showed that the increase in number of visitors to a reserve
leads to an increase in the number of introduced plants species. This is probably due to the
importation of propagules by the visitors themselves, or by attaching to vehicles. If the
hypothesis that an increase in tourism will lead to an increase in biological invasions holds
true, the short-term benefits of increased revenue will place an ever-increasing demand on
resources in the long-term. Macdonald et al. (1989) also indicate that habitat modification
leads to an increase in alien plant species, through building of roads, campgrounds and
other facilities.
Many forest managers simply cannot identify many of the invading alien species
(Macdonald, 1991) and rely on a few organizational experts to cover vast areas. In
practical senses, this is simply not possible and rangers, game guards, tour guides and
others staff (and suitably trained volunteers), that are operating in the field on a daily basis
need to be responsible for detecting and reporting invasions (Pauchard & Alaback, 2004).
As with many other aspects of PA management, fences and other artificial
boundaries are ecologically meaningless. Protected areas, even those of millions of
51
hectares, are islands and need to adopt an approach that is outward looking and considers
the broader physical and social environment. Examples of invasive species causing
damage in PAs are numerous in the terrestrial, freshwater and marine environments and
invasive alien species have been a major concern for PA managers (Howard, 2003).
3.22. Risk assessment of invasive plants
This refers to an approach that seeks to identify the relevant risks associated with a
proposed introduction and to assess each of those risks. Assessing risk means looking at
the size and nature of the potential adverse effects of a proposed introduction as well as
the likelihood of them happening. It should identify effective means to reduce the risks
and examine alternatives to the proposed introduction. The proposed importer often does a
risk assessment as a requirement by the decision-making authority (Shine et al., 2000).
Risk assessment associated with invasive weed species has to date focused
primarily on assessing the risk of invasion and/or establishment in uninfested areas. It is
suggested that this approach is relevant only to those species with limited or unknown
local distributions (Sing and Robert ,2003). The majority of managed invasive weeds fall
outside of this category. Weed management options included in a variety of environmental
impact assessments generally list no treatment within reviewed strategies. However,
quantitative or even qualitative evidence of invasive species impacts seldom support the
stated outcome (Sing and Robert ,2003).Before introducing any plant into Bangladesh
from any country, assessment of the possible risk of ecosustem damage should be
assessed. Othrewise society must pay the damage in terms of mass ecological damage of
the country.
3.23. Justification of planting only native trees in afforestation/ reforestation/
landscape plantings
Native plants are believed to be superior to introduced species because of their
better growth, reduced likelihood to become invasive, their indirect and direct biodiversity
value and their contribution to local sense of place. In all cases there are exceptions where
non-native species play an important role. Interest in landscaping with native plants has
grown rapidly in recent decades, but there is also a rise in ‘native only’ policies where
52
attempts are made to exclude introduced and exotic species from landscape schemes
(Kendle and Forbes, 1997). There are five common arguments that are forwarded
concerning the importance of native plants and the dangers of introduced aliens or exotic
species (Hitchmough and Dunnett, 1996; Gilbert and Anderson, 1998).
1. Natives grow better, or are more hardly or disease resistant than exotics:
Simple observation and common experience quickly refute this argument. What it is
always possible to find instance where poorly chosen exotics perform badly, agronomists,
foresters and horticulturists have shown over centuries that many of them can grow
outside of their place of origin without problems. At sub-specific level a lot of work on
‘provenance’ of seed source has been done by foresters. Whilst again it is possible to find
comparisons where locally adapted provenances outperform imported stock (Jones and
Evans, 1994) there are also examples where the opposite is true (Lines, 1987).
Not only can non-natives grow well, and not only are we dependent on many of
them for food, shelter, cloths etc. but some can perform functions that ultimately benefit
native species, such as the use of soil-building species in derelict land reclamation. These
potential benefits are reviewed by Williams (1997) who argues that possible functional
benefits of non-natives in natural habitats include:
Structural diversification and niche creation
Food supply
Facilitation of regenerations of natives (nurse species)
Modification of disturbance (e.g. reducing erosion or fires)
Directly compensating for the loss of a native that was important
for ecosystem function.
It is true that many exotic species are not so well adapted as to form reproducing and self-
sustaining populations out of their range, but that is actually one of their advantages in
many land use situations as they are unlikely to become weeds.
2. Exotics are likely to become invasive and out complete natives: Whilst being
identified as less well adapted to our climate than natives, exotics are simultaneously
expected to grow much better and to become invasive weeds (e.g. Gilbert and Anderson,
1998). Invasiveness is of course a serious problem and weed invasions are causing havoc
in habitats worldwide. An extensive range of legislation and policy necessarily underpins
international and national attempts to control the spread of potentially damaging species,
but for this to be effective it is important for implementation to be well focused. The
53
greatest source of confusion is that it is false to attribute the risk of invasion to aliens
alone.
Despite frequent implied association in the literature, invasiveness and exotic
status are not really closely correlated. Most aliens in the Bangladesh are not exotic weeds,
whilst some natives are. The term ‘invasive’ should only be applied to alien species, whilst
for native we should use the less pejorative term ‘expanding’, which is more like semantic
politics than an objective assessment. On reflection, the invasive ability of natives is not
surprising. These are plants that have proven reproductive ability within their climatic
range and they are often very able to exploit opportunities created by, say, excessive
habitat disturbance or land use change. In many cases in landscape work it is, therefore,
the very absence of reproductive capability in exotic species, which obviously cannot be
guaranteed for natives, that makes them so useful. If exotics have any unique capability to
be weeds, it is because out of those that can reproduce, some of them may lack local pests
or pathogens that would put constraints of their reproductive ability. However, the
disappearance of constraints can also happen to natives, for example, if a major predator
goes through a population decline). Sometimes existing but rare indigenous species can
become weeds because of change in land management (Garrott et al., 1993
3. Native support many more associated species than exotic species: It is known
that there is a close relationship between native plants and co-adapted feeding
invertebrates. As a general rule the longer a plant has been established within a region’s
flora the number of associated species that have adapted to feed on it (this process is
ongoing – nature allows for new arrivals even if some scientists do not). It need not hold
true for all circumstances or for other forms of plant-animal and plant-plant relations. For
example:
Non-natives can carry a high biomass of those invertebrates that they do support,
thereby fuelling a food chain (Gilbert, 1989). This may be because they lack some
of the defenses against invertebrate feeding that would be shown by the co-adapted
native plants.
Non-natives may have beneficial structural effects within a habit, such as
providing shelter for over-wintering birds or habitats for lower plants (Harding and
Rose, 1986).
They may produce animal food at times when the native flora does not.
54
Non-natives may be able to survive in unusual circumstances where the native
flora will find it difficult.
The range of associated species may not be able to colonize all habitats or all life
stages of the natives they are associated with. Conversely for most of our
introduced species we have never explored the invertebrate list that they may
support if allowed to become veteran trees in ancient woods in the countryside. So
on balance, natives do often support more feeding invertebrates, but this does not
merit an assumption that the conservation value of non-natives is negligible.
4. Native genetic diversity needs to be protected as part of the world’s store of
biodiversity: It is unquestionable that native plants represent each country’s own slice of
the world’s genetic diversity and there is a local responsibility to protect them. It is,
however, worth balancing this point with a recognition that form a global representative
non-natives may represent a resource of genetic diversity that has been lost or suffered
massive depletion in its country of origin. One example is the Bermuda Cedar (Jumiperus
bermudiana), which is a self-regenerating timber tree in St Helena but is a threatened
species in Bermuda. Lugo (1997) tells a similar story with Delonix regia, naturalized and
common in Puerto Rico, and in danger of extinction in its country of origin, Madagascar.
Increasingly conservationists will be faced with situations where a species’ original habitat
has become unsuitable because of environmental change, and deliberate translocation
outside of its former range in the only option (Davis, 1989). Similarly where there is only
a constrained vulnerable population, extension outside of the native range may be seen as
an important insurance strategy (Maunder, 1992).
In many cases different native ecotypes, and even native species, freely interbreed
to produce hybrids (Cousens, 1963) but the process of environmental selection continue to
operate and usually re-establish genetic boundaries. In fact this hybridization is an
important evolutionary process and the hybrids can sometimes directly support a greater
range diversity than when species are kept pure (Whitham et al. 1999). They often
accumulate the invertebrate taxa of both parents, rather than exclude them. Some
additional invertebrates depend on the hybrids. This seems to be because the hybrids often
show less resistence to exploitation by associated biota, such as invertebrates, than
resistant pure species do (Whitham et al. 1999). For artificially inbred populations
breaking up gene complexes may lead to better adapted individuals than the parents are
(Fenster and Dudash, 1994).
55
5. Native plants are regionally appropriate and define our landscape character:
The concept of regionally appropriate vegetation clearly has importance. Plants do help to
define the landscape character of an area. However, once again it does not follow that
native plants are always the most appropriate and it certainly does not follow that non-
natives do not have a place. The pine forests of Scotland (Pinus sylvestris) are a
fundamental part of the atmosphere and character of the region, but many would feel that
the landscape of Breckland, East Anglia in England would also be compromised if lost
the introduced shelter-belts of the same tree (Brown, 1997).
We appreciate plants for their diversity, interest, beauty and geographical and
cultural histories rather than condemning them because they ‘did not originate here’. This
perspective opens doors to ethnic groups, by recognizing the positive side of the urban mix
and providing opportunities for dialogue to begin. More fundamentally it also remains all
of us that protection of local nature is just a tactic in the wider issue of protecting global
nature.
Ending remark: The above functional critique of the importance of native plants in
the landscape amounts mostly to an illustration of how, in a complex environment super-
imposed with equally complex human history, culture, values and aspirations, it is
impossible to characterize one group of plants as ‘superior’ than others. This is especially
true when the classification system is as nebulous and as value-laden as our definition of
native. In essence it is clear that all of the arguments given to favour the use of native
plants in the landscape contain truths, but they can never be always true and they cannot
all be acted on. So in the conclusion, are native-only policies justified? Of course not.
They are often better, and we would subscribe to the argument that local character and
local species should always be given a presumption in their favour when planting
anything, but this is not the same as endorsing condemnation of alternatives or ‘arbitrary
discrimination against exotic species’ (Brown, 1997).
Chapter 4: Instruments dealing
with IAS
It is increasingly apparent that international cooperation is essential for the
prevention, eradication and control of invasive alien species (IAS). This has been formally
56
recognized by the UN Convention on Biological Diversity (CBD) and in various other
international forums. Various other organizations dealing with IAS has been given below:
4.1. The Global Invasive Species Database (GISD):
The Global Invasive Species Database (GISD) is primarily a management
information and awareness-raising tool. A database was compiled comprising of plant
species that are currently viewed as highly invasive in natural habitats in various regions
of the world. The basis for the plant list was an extensive literature search and information
available from the Internet. The database includes 814 plant species and each species was
complemented by ecological and geographic features such as life form, geographic
distribution, family, and economic uses. It has a focus on geographic and information gaps
so that more of the world’s communities can have access to relevant information (Browne
and Maj, 2003). The database was analyzed with regard to taxonomic patterns of invasive
plant species, patterns of economic uses and whether there are differences among life
forms with regard to their geographic distribution and economic uses. The most prevalent
life forms were perennial herbs, followed by treesand shrubs.
The Global Invasive Species Database (GISD) provides a broad audience with easy access
to authoritative information on IAS. It disseminates globally sourced information,
including good practice, case studies, specialist’s knowledge and experience. The database
has a dual aim: to raise awareness about invasive alien species, their impacts, and the
opportunities to fight back; and to be a management tool assisting decision makers,
practitioners and communities to address their IAS problems. Now the GISD contains
profiles of more than 250 species that threaten biodiversity, ranging from microorganisms
to plants and animals. Future plants include ongoing population of the database with more
profiles and development of a CD-ROM version of the database for those who have poor,
or no access to the Internet, -bridging the digital divide (Weber, 2003).
4.2. Global Invasive Species Program (GISP)
The need for concerted global action to combat IAS has led to the creation of the
Global Invasive Species Programme (GISP). The Programme was established in 1 997 to
address the global threats caused by IAS and to provide support to the implementation of
Article 8(h) of the Convention on Biological Diversity (CBD). GISP is operated by a
consortium of the Scientific Commiftee on Problems of the Environment (SCOPE), CAB
57
International (CABI), and the IUCN-World Conservation Union in partnership with the
United Nations Environment Programme (UNEP).
In essence, GISP aims to conserve biodiversity and sustain human livelihoods by
minimising the spread and impact of IAS. To realise this mission, GISP operates through a
“Partnership Network” comprised of scientific and technical experts on IAS issues from
around the world. GISP stakeholders are its Partners-governments, intergovernmental
organisations, non-governmental organisations, academic institutions, and the private
sectorThe Global Invasive Species Programme (GISP) has been instrumental in
encouraging international scientific collaboration to improve understanding of IAS, their
impacts and their management.
4.3. Other organizations working with IAS
Aside from the GISP numerous international instruments have been developed to
deal with IAS. The most comprehensive is the 1993 Convention on Biological Diversity,
which calls on its parties to “prevent the introduction of, control or eradicate those alien
species which threaten ecosystems, habitats or species” Article 8h). The World
Conservation Union (IUCN), through its Invasive Species Specialist Group, has also
worked to raise international awareness of IAS issues, through its network of experts and
its list server, newsletter and database. Several international initiatives against invasive
species are now underway or planned, under the auspices of GISP and with the
involvement of IUCN and other organizations (Clout, 2003). Another is the 1952
International Plant Protection Convention (IPPC), which applies primarily to plant pests,
based on a system of phytosanitary certificates. The IPPC was extensively revised in 1997
to meet some of the new challenges of plant pests.
The International Maritime Organization (IMO) has also been working on ways to
prevent the spread of marine alien organisms in ballast water and sediments since the mid-
1970s. In 1997, the IMO Assembly adopted Guidelines for the Control and Management
of Ships’ Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and
Pathogens. The Guidelines are intended to assist Governments and appropriate authorities,
ship masters, operators and owners, and port authorities, as well as other interested parties,
in minimising the risks through ships entering their ports, but call for this issue of
worldwide concern to be addressed through action based on g\lobally applicable
regulations.
58
Table 2: A partial list of international instruments dealing with IAS
Cartagena Protocol on Biosafety to the Convention on Biological
Diversity
2000
IUCN-Guidelines for the Prevention of Biodersity Loss Caused by
Alien Invasive Species
2000
Guidelines for the Control and Management of ships’ Ballast Water
to Minimize the Transfer of Harmful Aquatic Organisms and
Pathogens
1997
Convention on the Law of Non-navigational Uses of International
Watercourses
1997
Agreement on the Application of Sanitary and Phytosanitary
Meassure
1995
Convention of Biological Diversity 1992
Protocol for the Conservation and Management of Protected Marine
and Coastal Areas of the South East Pacific
1989
ASEAN Agreement on the Conservation of Nature and Natural
Resources
1985
United Nations Convention of the Law of the Sea 1982
Convention on the Conservation of Antarctic Marine Living
Resources
1980
Convention on the Conservation of European Wildlife and Natural
Resources
1979
Convention of Migratory Species of Wild Animals 1979
The Convention on Wetlands of International Importance especially
as Waterfowl Habitat
1971
59
Agreed Measures for the Conservation of Antarctic Fauna and Flora 1964
Plant Protection Agreement for the Asia and Pacific Region 1956
International Plant Protection Convention 1952
-
Chapter 5: Details of some
invasive plants in Bangladesh.
Actually there is no accurate list of invasive plants in Bangladesh. Some researchers
tried to make partial list of invasive plants in Bangladesh, which is described earlier.
Acacia auriculiformis, Eucalyptus camaldulensis, Acacia mangium, Melaleuca
leucodendron, etc. all are blamed of biological invasion in different countries of the world.
In Bangladesh, there are extensive plantation of these trees and also seen as guilty of
having negative impact on indigenous biodiversity. But no doubt that Eupatorium
odoratum, Mikania cordata, Ipomea carnea, Ageratum conyzoides, Imperata cylindrica,
Lantana camara, and water plants like Eichhornea crassipes, Pistia stratiotes etc. are
doing large scale damage to our ecosystem. Description of these plants are given below:
5.1. Akashmoni (Acacia auriculiformis) A Cunn. ex Benth.
Local names: Akashmoni, Akashi, Family: Leguminosae (Mimosoideae)
5.1.1. Akashmoni in Bangladesh : There is no record of how and when A.
auriculaeformis was imported to Bangladesh, but indications are available that the species
60
was first imported by tea planters for its use as a shade tree about 25-30 years ago (Das,
1986). The species is native to the savannas of Papua New Guinea. The Islands of the
Torres Strait and the northern areas of Australia. Because of its ability to grow on very
poor soils or difficult sites, it has been introduced in several tropical countries such as
Solomon Islands, Indonesia, Malaysia, India, Nigeria, Tanzania, The Philippines and
Bangladesh.Now it is an fastly spreading invasive plant in Bangladesh and an important
constituent of plantation forestry throughout Bangladesh.
5.1.2. Description: Acacia auriculiformis is a moderate sized evergreen tree, attaining
a height of 10 m, rarely upto 15m. and 60 cm diameter in about 30 years, which is its
normal length of life. Bark smooth white or light grey, somewhat fissured in later years,
twigs green without spines. The leaf stalks are modified into flattened blade called
phyllode, which is narrowly oblong, slightly curved or sickle-shaped, leathery and dull
green with 4-6 parallel nerves, 8-18 cm long, 1, 2-3, 7 cm broad. Young seedlings have
usually normal leaves. Flowers 4 mm long, tiny, rich yellow, fragrant, crowded in axillary
spikes, 4-9 cm long. Pods are 1.2 cm wide, flat, hard almost woody and much twisted in
irregular coils, initially green but turn brown on ripening. Coiled pod 2.5-3, 8 cm wide,
splitting open along the edges( Luna,. 1996).Fruits are somewhat earshaped, brown,
contorted pods that persist for months.
5.1.3. Distribution: The species is native to the savannas of Papua New Guinea. The
Islands of the Torres Strait and the northern areas of Australia. It ranges from Queensland
(north of about 250S) to the northern parts of the Northern Territory, across southern New
Guinea to the Kei Islands of Indonesia.
5.1.4. Habitat: 4. It grows best under humid, tropical conditions with annual
temperatures of 26oC to over 30oC. However, it is equipped to grow on dry savanna
conditions, since its thick, leathery “leaf” (actually a flattened and expanded leaf stalk,
phyllode) withstands heat and desiccation. A. auriculiformis is drought resistant, that is, it
can survive in areas with a dry season up to 6 months. Although it is well adapted to
drought, it grows most quickly in humid climates. It survives in areas with less than 1,500
mm annual rainfall, however, it is better suited to climates with annual rainfall from 1,500
mm to more than 2,000 mm. In the Northern Territory, Australia A. Auriculiformis grows
mainly on lowland sites, along drainage channels above tidal range, on the edges of dunes,
behind mangrove swamps and along river levees.
61
The tree will grow with practically no maintenance, in a wide range of deep or
shallow soils including sand dunes, mica schist, compacted clay, limestone, podsols,
laterite and lateritic soils. It may also grow in other problem soils such as the eroding
hillslopes, mining spoil, as well as in highly acid and alkaline soils. These problem soils
are often poor in nutrients, however, since A. Auriculiformis produces profuse bundles of
root nodules, it can survive in such areas very low in nitrogen and organic matter where
most eucalyptus and other species fail. In West Bengal, it grows well on red shallow
lateritic soils. Soil pH ranges from 3.0 to 9.0. Its altitudinal range is from sea level to about
600 meters in elevation. Introduced as a fast-growing tree for home and commercial
landscapes. It is frequently used as a street and parking lot tree, institutional plantation,
barren land, and wasteland and degraded site plantation and will survive with little care or
maintenance (Hammer, 2003). Recent works suggest that interactions between plants and soil
microbes are important. Acacia species are able to use soil microorganisms to enhance resource
availability allowing a better resource partitioning than native plants (Ferreira et al., 2003).
5.1.5. Phenology: It flowers profusely at an early age, and continues fruiting almost
continually. In Bangladesh, the seeds are collected from November to April but the best
time is January/February when the pods mature. The production of flower and fruit depend
on the moisture content of the soil. In most cases, flowering occurs twice in a year.
5.1.6. Silvicultural Characteristics: It is a light demanding species. It is moderately
drought resistant, but fails to withstand severe drought, and is fire-tender. It grows very
fast even on marginal land. In Papua New Guinea, A. Auriculiformis planted on too
infertile land grew to 6 m tall in 2 years with a diameter of 5 cm and had reached 17 m in
8 years (Nicholson, 1965).
5.1.7. Natural Regeneration: It is a colonizing species in its native habitat, which
provides the initial ground cover and shading for the establishment of rainforest. It flowers
profusely and produce large amount of seeds, which germinate easily. Big number of
regeneration is found under the tree but because it is an intolerant species, most of the
seedlings are smothered and failed to regenerate in the shade beneath the closed rainforest
canopy. It is only when the canopy is open and large amount of light penetrating to the
ground layer that young regeneration will have the chance to develop.
5.1.8. Ecological threat: Acacia species were introduced as a fast-growing tree,
with the objective to supplement fuelwood and restore degraded lands. However, now
Acacia has become invasive, menacing native flora by reducing native species density and
62
biodiversity. Acacia is exceptionally weedy along roadsides and other disturbed sites and
readily invades habitat and the margins of hardwood forests (Hammer, 2003). The tree is
fast growing and fruits at and early age. Birds are the primary seed dispensers. Once
established in natural areas it can quickly form extensive colonies that replace native
vegetation.
5.2. Mangium (Acacia mangium), Wild.
Local name: Mangium, Family: Leguminosae (Mimosoideae)
5.2.1. Acacia Mangium In Bangladesh: Mangium is a fast growing and fastly
spreading timber species introduced in Bangladesh by the Bangladesh Forest Research
Institute. It has been planted in the forests by the Forest Department (Kabir et al., 1994). It
was first introduced in this country in 1979 and later in 1980. The species has been
introduced to Bangladesh and is being planted since 1983 (Latif et al., 1993).
5.2.2. General Description: Acacia mangium grows as tall as 30 m with a straight,
clear bole that may be unbranched for more than half its total height. Stem dimeters up to
90 cm have been recorded in the natural forests of Queens land and Papua New Guinea.
The bark of older trees is thick, rough, and hard, and is furrowed longitudiually and varies
from dark brown to fawn in color. The inflorescence is a loose spike up to 10 cm long,
made of small white or cream flowers (Latif et al. 1984).
5.2.3. Distribution: It is native to three small areas of Queensland, Australia, the
South Western portion of New Guinea and the Molluca Island, of Eastern Indonesia.
Populations extend from a northern limit in Irian Jaya of 0o50’S to the most southern
occurrence in Queensland, Australia at about 19oS. It was introduced in Sabah in 1966 and
in 1978 in Bangladesh.
5.2.4. Climatic Conditions: Experiment conducted in Bangladesh since 1979 had
indicated that the species can be grown even in dry and poor soils, especially in the hilly,
barren and undulating areas. It also competes well with Imperata grass (Das, 1984). On
good sites in Bangladesh, the tree had an average height of 8 m and an average diameter of
7.7 cm. In its natural habitat (Queensland, Australia) it is a pioneer species which
establishes itself often sites have been disturbed. It occurs principally in the coastal
63
tropical lowlands, on the fringes of mangrove as well as in reverine forests. It does not
occur in mature rainforest but is most often found on the forest margins.
5.2.5. Ecological threat: A. Mangium is a very profilic seeder. Abundant
regenerations are reproduced in the natural stand. As a pioneer species, the trees occur in
small groups, then may occasionally dominate large areas. It establishes itself after sites
have been disturbed, particularly by fire. The seeds can remain viable for more than one
year, and fire naturally scarifies them and enhance germination. The stumps of young trees
coppice.
5.3. Eucalyptus Species
5.3.1. Eucalyptus Introduction in Bangladesh: Eucalypt has a long history in
Indian subcontinent. It was first planted around 1790 by Tippu Sultan, the ruler of Mysore,
in his palace garden on Nandi hills near Bangalore. According to one version he received
seed from Australia and introduced about 16 species (Shyam S. 1984). But according to
Tanvir (1996) its first introduction in the sub-continent dates back to 1843 as single trees,
arboreta and roadside plants. Eucalypt has come to stay in India (Palanna, 1996).
Sometime in the 1930’s Eucalyptus citriodora was haphazardly introduced into eastern
Bangladesh by tea estates as an ornamental. This species was spread throughout
Bangladesh by botanists, foresters, gardeners and other people, but no formal plantations
were developed (Davidson and Das, 1985). First interest in other species of eucalypts was
recorded in 1963 when germination tests of three species, E. citriodora, E. tereticornis and
E. botryoides were conducted in the Silvicultural Research Ranges in Mymensingh and
Chittagong. From then on until 1984 about 37 species were introduced and tried
excluding those introduced in the tea estates. After five years of experimentation, the
Bangladesh Forest Research Institute in Chittagong have arrived at a conclusion that E.
camaldulensis, E. tereticornis and E. brassiana could be profitably grown in the soil and
climatic conditions of Bangladesh (Das 1984; Davidson, 1985). Out of the little more than
one million ha of land under existing forest in Bangladesh (FAO 1995), eucalyptus
occupies a substantial land area. Besides, eucalyptus enjoys a good popularity in social
forestry, home garden and even in the cropland agro-forestry practice in our country. (Paul
et al., 1998). Eucalyptus camaldulensis of Petford provenance is being planted fairly
widely on a commercial basis for fuelwood and other purposes in Bangladesh.
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Eucalypts are amongst the most widely planted trees in the world. Because of their
fast growing character and outstanding physiological, genetic and silvicultural attributes
(Davidson 1985), these trees are extensively used for afforestation and reforestation in 58
countries (FAO 1981)
5.3.2. Eucalyptus camaldulensis, Dehnh
Local name: Eucalyptus, Family: Myrtaceae
5.3.2.1. General Description: It is a large-boled tree in its natural habitat, medium-
sized to tall tree, reaching up to 25 meters tall, with erect or spreading branches and a
smooth bark that may be pink, cream or white. Occasionally, the dbh is 1-2 meters. The
trees are often crooked. Juvenile leaves, ovate to broadly lanceolate, tend to be pendant;
adult leaves, narrow lanceolate, alternate, petrolate.
5.3.2.2. Distribution: This is the most widely distributed of all eucalyptus, occurring
along or near almost all of the seasonal water courses in the arid and semi-arid areas. It is
widely planted in plantations throughout the world ranging from the Mediterranean, Spain,
Morocco, Pakistan, Uruguay, Argentina, Kenya, Nigeria, Tanzania, India, Bangladesh, etc.
In its natural state, the latitudinal range is about 12.5o - 38oS. It is one of the most widely
spread eucalyptus in Australia occurring naturally in all the Australian states except
Tasmania.
5.3.2.3. Climatic Condition: This species grows under a wide range of climatic
conditions from warm to hot, sub-humid to semi-arid with the mean maximum
temperature for the hottest month in the range 27o – 40o C and the mean minimum for the
coldest month around 3o – 15o C. In the native habitat the mean annual rainfall range is
mostly 250 – 600 mm, while a few areas receive up to 1250 mm and same as little as 150
mm.
5.3.2.4. Physiographic, Edaphic and Biotic Requirements: The species is usually
found on acidic soils (pH 4.5-5.5) of low fertility, low in phosphorus, shallow and sandy
and even in some sites it tolerates passing floods (Salazar 1988).
It is also adapted to sandy alluvial soils. It perform very poorly on calcareous and
shallow soils over limestone. It is important to know the right provenance for planting in a
given site condition as the seed from a specific origin may grow better in a specific site.
65
Although the tree is a riverine species of the plains it can be grown in highland areas of
over 1200 meters. However, for better growth development it should not be planted on
areas higher than 700 meters.
5.3.2.5. Forest Types: It occurs along or near almost all of the seasonal watercourses
in the arid and semi-arid areas and is found along many other stream and rivers in the
southeast of Australia.
5.3.2.6. Silvicultural Characteristics: A light demander species in favourable sites,
Eucalyptus camaldulensis grows very fast. With the right provenance planted in
plantation, mean annual growth increments of 2 meters in height and 2 cm in diameter can
be maintained for the first 10 years. One good sites, plantations are managed on coppice
rotations of 7-10 years(Davidson and Das 1985). The species has a high root-shoot ratio,
which accounts for its drought resistance. Natural regeneration is reported under the
mother trees of 105 cm dbh for the first time from Sriganganagar (Rajashtan) on alluvial
sandy soil having good moisture due to irrigation (Nautiyal et al., 1994)
5.3.2.A. Criticism on Eucalypts:
At present eucalypt planting around the world extends to about 80 countries and
another 50 countries are in trial phases. Eucalypt planting is a controversial issue in some
countries where it has been planted extensively. Critics assert that: i) it has deleterious
effect on the hydrological balance; ii) it depletes the soil nurtrints; iii) it has an allelopathic
effect leading to inhibition of growth of other plants; and iv) it has a deleterious effect on
native animals (Ali, 1996).
5.3.2.B. Attributes of introduced Eucalypts:
It is important to understand the attributes of eucalypts planted in Bangladesh to
understand their environmental consequences. The most outstanding eucalypts introduced
are E. tereticornis and E. camaldulensis. These species, including others introduced
elsewhere as exotics, as E. grandis and E. urophylla in the Indo-Malaya region, tend to
have a number of characteristics in common:
a) They belong predominantly to the subgenus Sumphyomyrtus – individual members
of which may be characterized by a wider environmental tolerance than members of other
subgenera.
66
b) They are the more successful species capable of responding more positively to
better soil conditions- particularly higher soil fertility.
c) They are capable of rapid root development, particularly in depth. This may be a
general attribute of eucalypts growing, or capable of growing, away from moist regions.
d) The species usually reach early and strong peaks in current annual volume
increment (CAL). This peak may be as early as 4 years in E. tereticornis, 6-7 years in E.
grandis and 12-15 years in E. globulus. By the time the peak is reached wood volume
production on high quality sites may be in the range of 24 m3/ha/yr for E. tereticornis to
50 m3/ha/yr for E. globulus (Florence, 1992).
5.3.2.B.1. Water use by eucalypts:
Claims are made that eucalypts use excessive amounts of ground water by developing
a deep root system. In dry areas, though eucalypts develop long deep tap root in moist
areas, they mostly develop fibrous roots (Zimmer and Grose, 1958). Dabral et al. (1987)
observed that the fibrous root of eucalypts extend up to 18 m within a soil depth of 30 to
60 cm in moist areas. When moisture content varies at different localities of a site,
eucalypts may try to maintain growth by extending root systems in drier areas.
Where a eucalypt is planted in countries other than Australia, it is removed from its
regulated environment context, and the checks and balance imposed by site no longer
apply. For example, E. camaldulensis occurs naturally as a woodland in dry areas over
most of the Australian continent where the rate of water use is hardly an issue in the
Australian circumstances (Florence, 1992), it could become and issue where it is
established elsewhere as a forest on moderately fertile soil with good rooting depth and
access to a water table.
It is possible that where one of the more opportunistic of the faster growing
eucalyptus (e.g. E. camaldulensis) has access to a substantial water resource and where
there is a prolonged dry period with high vapour pressure deficts, large amounts of water
may be transpired (Florence, 1992).
5.3.2.B.2. Effect on soil fertility:
67
Eucalypts absorb a large amount of nutrients to maintain fast growth. Recent opinions
conclude that eucalypts could lead to the decline of soil fertility, as the forest land quality
in eucalypt plantation declines.
George (1986) concluded that the organic matter and exchangeable potassium are
depleted in the soil under eucalypt plantation than in woodlands, but no difference in
calcium and magnesium was observed.
In a study carried out in the Dry zone in Srilanka, it was observed that the soil under
Eucalyptus camaldulensis tend to become slightly acidic with the increase in depth
(Ranasinghe and Jaysuriya, 1991).
Scientific evidence from Sri Lanka made in short and long rotation eucalypt
plantations confirm findings reported from many other countries (Poore and Fries, 1985)
and Shiva and Bandyopadiyay (1985).
Impervious and/or highly erodible soils will be washed away more easily than porous
soils. One of the factors which can make soils under eucalyptus impervious is a non-
wettable or water repellent property which is found in both natural stands in Australia
(Hamilton 1964, Davidson 1967) and under exotic plantations water repellent soils are
abnormal soils which resist wetting by water , a behaviour which is caused by a
hydrophobic coating of organic origin on the soil particles (De Bano 1971). Water
repellent soils cause impeded infiltration and percolation, resulting in water moving over
and through the soil (Davidson 1967), causing patchy wetting of the upper soil horizons.
Blocks of soil near the surface may remain dry after considerable rainfall (Davidson
1967).
Water repellency is of course not restricted only to soils under eucalypts. It is also
commonly associated with certain other species and vegetation types such as citrus
orchards (Jamison 1942).
Other conditions being similar, the precipitation reaching the ground is 20-25 percent
more in eucalypts plantation than in the plantations of other broad leaved species (Hassan
1994).
Eucalypts leaf contains growth inhibitor such as tarpenes. This compound prevents
the germination of herbs and shrubs intended for underplanting. This has been proved to
be strong when the leaves are fresh, but the effect becomes faded as the leaves decay and
the inhibitor compound volatilizes (Hassan, 1994).
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5.3.2.B.3. Alletopathy /understory vegetation and eucalypts:
It is widely held in some countries, notably India, that eucalypts are strongly
allelopathic; that they produce foliar and root exudates directly toxic to other plants. It is
more likely that the effect of eucalypt on understory plants or adjacent crops are the result
of the very great capacity of eucalypts to complete for short supply soil resources
(nutrients and water). Where soil resources are not in short supply the understory
vegetation may be maintained under a vigorous tree canopy.
In India Dabral et al. (1987) found an undergrowth vegetation of Lantana spp.,
Murraya koenigii, Carissa karonda, Jasminum officinale, Mallotus philippensis and
Syzygium cumini under 16 year old eucalyptus hybrid plantation, at spacing 2m x 2m, at an
experimental site near Dehra Dun Forest Research Station. In our forest conditions
undergrowth under eucalypt plantings at 1.8m x 1.8m spacing but the diversity is less than
of native forest types. The composition observed could have been disturbed by weeding,
ground fire and shrub collection of local people and a confirmation study of the diversity
of undergrowth needs to be made under suitably undisturbed eucalypt plantation.
Lisa and Michelsen (1993) reported in Ethiopia that eucalypt leaf exudates have some
inhibitory effect on germination, and on reduction of shoot dry weight of four crops tested;
they state an allelopahaic potential rating from lower to higher as Cupressus lusitanica <
E. globulus < E. saligna < E. camaldulensis.
The nutrient accumulation is generally greater in species with a comparatively larger
crown biomass relative to stem size. The rangs of nutrient accumulation in E.
camaldulensis was established by Hopmans et al (1990). A considerable amount of N
accumulated in the leaves and twigs of eucalypt can be left in the forest environment, and
would compensate for the loss to some extent but in case of other macro nutrients some
corrective measures may have to be taken. This is very important, especially in the case of
eucalypts, because nutrient content in the litter of eucalypt is lower than other species as
they usually absorb nutrients before the shedding of litter (Banks, 1992).
5.4. Ipil-ipil (Leucaena leucocephala) (Lamb) de wit Family: Leguminosae (Mimosoideae) Local name: Telekadam; Common names: Ipil-ipil, house tamarind, white babool.
69
5.4.1. General Description: Depending on variety, leucaena is either a tall, slender
tree that may grow up to 20 m, or a rounded, many-branched shrub less than 5 m high.
Generally, the leaves are evergreen, alternate, bipinnate with 3-6 pairs of pinnae, each of
these with 10-20 pairs of sessile, narrowly oblong to lanceolate feathery leaves, often
almost translucent. The flowers are small, white and fluffy balls, usually self-ppllinated
and produce thin flat almost straight pods. More than 800 varieties of this species are
known
5.4.2. Distribution: The species is probably native to Mexico and northern central
America, and introduced to Indonesia, Philippines, Malaysia and other countries in South
East Asia, Hawaii, Northern Australia, India, Bangladesh, East and West Africa and
islands in the Pacific and Caribbea.
5.4.3. Habitat: Leucaena grows under a wide variety of climatic conditions, though it
is a tree of the tropics and sub-tropics where it grows upto an elevation of 500 m. The
species is capable of tolerating large variations in rainfall, temperature, wind, drought and
topography (NAS, 1977). The root system is characterized by well developed and deep
taproot which is capable of even breaking the impervious layer (Gray, 1968).
5.4.4. Silviculture Characteristics: This species is very light demanding. It grows
best in full sunlight and in high light intensities. Leucaena coppices readily from stumps of
almost any age. Coppice growth is more vigorous than seedling growth, new shoots of
Giant varieties reach 6 m in one year.
The species is an aggressive colonizer. Because of its copious seed producing nature
and special seed dispersal mechanism of ripe seeds splitting naturally along both the edges
of the pod and ejecting 15-30 seeds per pod it easily escapes from cultivation and colonise
the adjoining agricultural fields. The pods fallen on the ground are also dispersed by
animals, wind etc(Patil & Kumar, 1990). Ipil-Ipil can naturally regenerate by seed and
coppice (Zabala, 1985). Since the species is prolific seeder, harvesting the crop by clear
cutting exposes the seeds to sunlight (being scarified), then profuse growth of seedlings
follow.
5.4.5. Ecological threat: Invasion by Leucaena leucocephala and its impact on the
native plant community: Leucaena leucocephala is native to Central American savannas.
It is an invasive leguminous shrub that has become naturalized on many countries. It forms
dense thickets in disturbed areas. The invasion of L. Leococephala promotes the invasion
70
and establishment of more aggressive alien tree species. Consequently, the invasion and
expansion of L. leucocephala has had a severe effect on the native plant community
(Yoshida and Shuichi, 2003). Leucaena is a weedy, fast-growing tree that readily invades
coastal strand, pine rockland, the margins and canopy gaps of hardwood forests, and open
disturbed sites. Population densities can be high if left unchecked. (Hammer, 2003).
5.5. Melaleuca (Punk Tree).
Melaleuca quinquenervia S. T. Blake
Melaleuca leucodendron L. f.
Family:Myrtaceae.
5.5.1. Melaleuca debate: In the 1970’s, the popularity of melaleuca took a hit.
Biologists and land managers are now beginning to curse melaleuca as it spread
unchecked across the landscape at the expense of native plants. Severe wildfires were
being blamed on the prevalence of melaleuca. Melaleuca is now a scapegoat for people’s
itchy eyes and runny noses. Biologists and land managers were now thinking of ways to
rid themselves of the melaleuca menace (Pernas and Francois, 2003). Melaleuca rapidly
invades moist, open habitats, both disturbed and undisturbed, and forms dense,
impenetrable forests. In general, invasion is less prominent on forested sites than marshes.
5.5.2. Native range: Eastern Australia through Malaysia and Myanmar (Burma).
5.5.3. Description: Melaleuca is a large evergreen tree typically 65-100 feet in
height with brownish white, many-layered papery bark. Melaleuca (Melaleuca
quinquenervia) trees grow quickly, typically 3-6 feet per year in marshes and swamps.
An upright, slender tree usually single-trunked but may develop multiple trunks. Trunk
and branches covered with thick layers of white, papery bark, peeling off in sheets. Leaves
are dull green, 2 to 8 inches long and 3/8 to ½ inch wide, stiff and highly aromatic when
crushed. Flowers are showy and produced in bottlebrush-like spikes with prominent ivory-
white stamens. Fruit broadly cylindrical, thick-walled, capsules to 3 mm (3/8 in) wide,
in clusters surrounding young stems; each capsule holding 200-300 tiny seeds. Dust-like
seeds are enclosed in rounded, tightly clustered, persistent, greyish-brown capsules
produced along the stems.
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5.5.4. Ecological threat: Melaleuca causes both ecological and public health
problems. It rapidly colonizes freshwater wetlands, almost completely displacing native
vegetation and degrading wildlife habitat. Any physical disturbance, such as fire, freezes,
felling, and even herbicide application liberates millions of seeds from a single tree. The
tree can reproduce from seed when only one or two years old and is still undergoing rapid
population expansion in the Big Cypress National Preserve and the northern portion of
Everglades National Park. Melaleuca also constitutes a significant health hazard because
the flowers and new foliage produce airborne substances that cause severe asthma-like
symptoms in sensitive people.
Invasive characteristics of Melaleuca include its evergreen habit, prolific seed
production, frequent flowering and flood and drought tolerance. This tree threatens
biodiversity of native flora and fauna by diminishing the value of their habitat (Serbesoff-
King, 2003).
This non-native tree is a notorious invading tree in different countries of the world, as
for example, rapidly displacing native cypress and sawgrass in the Everglades(U.S.A.).
Melaleuca can flower five times per year. Any damage to the tree that cuts water flow to
the stems containing seed capsules, such as fires, freezes, and control techniques, will
result in seed release. Seeds can remain viable for 10 years, and a single tree can store
2-20 million seeds.
5.5.4.1. Environmental damage caused by melaleuca
Melaleuca forms dense stands resulting in the almost total displacement of native
plants that are important to wildlife.
Melaleuca forests represent a serious fire hazard to surrounding developed areas
because of the oils contained within the leaves that create hot crown fires.
Melaleuca forests provide relatively poor habit for wildlife and almost totally
displace native plant species
Melaleuca invasions alter the landscape of the Everglades by creating
monospecific forests in formerly treeless sawgrass marshes.
Melaleuca forests alter ecosystem properties such as water flow in the Everglades.
Dense stands of melaleuca trees produce hot crown fires that result in native tree
mortality and pose a significant threat to developed areas.
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5.6. Dul kolmi ( Ipomoea carnea) .
Invasion by Ipomoea carnea: Invasiveness of certain introductions has been obvious
because of their rapid expansion and widespread detrimental ecological impacts. Ipomoea
carnea, a native of South America has spread fast in Indian subcontinent during the last
three decades and has become an obnoxious aquatic weed (Kandasamy, 2003).It is a
Common weed of all habitat In Bangladesh(Hossain and Pasha, 2001). It is a perennial
diffuse or straggling shrub growing to a height of 2-3 m. Can come up in waterlogged
areas and is resistant to drought. Widely seen in roadside and farm ditches, waterlogged
areas, shorelines, river-sides. In Bangladesh it is seen in almost all districts
5.7. Ageratum conyzoides
Family: Asteraceae
Invasion by Ageratum conyzoides – the exotics from South America (with wide
ecological amplitude apart from effective and well-organized dispersal mechanism) have
overpowered natives and caused much ecological harm because of their invasion, density
of native flora and crop productivity has diluted affecting adversely the socio-economic
condition. How their strong allelopathic potential and colonizing character has changed
the soil fertility, the ecological succession and thereby whole ecological dynamics (Kohli
and Kuldip, 2003).
It is a Common weed of waste and cultivated field in Bangladesh; blamed as
aeroallergic pollen species (Hossain and Pasha, 2001)
5.8. Siam weed (Chromolaena odorata (L.)
Family: Asteraceae
5.8.1. Intriduction: Of all the species under the genus Chromolaena, Siam weed
(syn. Eupatorium odoratam.) is the best known because of its wide distribution.
Chromolaena odorata (L.) is a dominant, competitive and difficult invasive species in the
humid forest zone of Western and Central Africa (Ngobo et al., 2003) Other affected
countries are West Africa, South Africa, the Indian subcontinent, and the Pacific. In
73
Bangladesh it is a common invasive weed of fallows and bush fallow sites, wasteland and
forests.
5.8.2. Origin: Originating from South and Central America it later reached Southeast
Asia in the 19th century. Singapore was the first entry point and became present in other
Asian countries.
5.8.3. Vegetative characters: C. odorata is a perennial shrub, which attains a height
of 3 m and grows well in open areas, riverbanks, creeks and plantations of coconut, palm
oil, citrus, tubers and rice. In shaded areas, it could reach a height of 10-20 m, adopting a
climbing habit. It grows at a rate of 20mm/day or 5 m/year.
Chromolaena odorata was appreciated for its ornamental value, having pale purple
and offwhite-coloured small flowers blooming during winter. This probably led to its other
name “Christmas bush”. Because the flowers are produced in masses, they tend to cover
the whole plant. It continues to flower for three to five dry and windy months. Seed
production is prolific with up to 87,000 seeds per mature plant or 400,000 per square
meter having been recorded. Seeds germinate readily (Khanna, 2003). The condition
favours rapid drying of fruits and dissemination to wider ranges as well. Seeds are also
dispersed by sticking to clothings, farm implements, vehicles, footwear and animals. Seeds
may soon germinate after rain or remain viable in the soil for five or longer years. It is also
valued as a good ground cover
5.8.4. Chemical Compounds: Alkaloids, camphor, vitamin C, eupatorin, tannin,
essential oil, sesquiterpene.
5.8.5. Negative impact of chromolaena: Consumption of leaves and young shoots of
C. odorata by pasture animals may endanger their lives. It may cause diarrhea, abortion
and worse, death due to its high nitrate content. As a result, unmanaged areas are always
left as wastelands. In a one-hectare land, biomass production of C. odorata averages 15
tons. For humans, it may cause allergies, asthma and skin problems. Dried patches of the
weeds burn easily, opening new areas ready for invasion.
Chromolaena-dominated fallows and bush fallow site increasing intensity of land
management seemed to be a significant predictor of falling plant diversity (Ngobo et al.,
2003). Increased level of land use intensity associated with increased level of disturbances
in fallows correlate with the Chromolaena. dominated fallow type, and seem to facilitate
the invasion by weeds, both during the fallow phase and the subsequent cropping season..
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Chromolaena was ranked as the farmers’ most important constraint to crop production in
short duration fallow systems. The species is not only consistently abundant throughout
the cropping period, but it was also dominant in fields established after clearing less
intensively farmed fallow types This species has been nominated as among 100 of the
“World’s Worst: invaders (Ngobo et al., 2003).
5.8.6. Control: Chemicals may be applied to immediately suppress the weed but
these are expensive and dangerous to some extent. Slashing of the weed is also an
ineffective control because new shoots may develop from broken and cut stems.
Biological control is still recommended such as the use of Pareuchaetes pseudoinsulata, an
archtiid moth belonging to Lepidoptera. It may be successfully established in countries
such as Malaysia but not in other areas. The agent is a voracious leaf-feeder. Other
biological agents are still being considered like Procecidochares connexa, Mescinia
parvula, Melanagromyza eupatoriella (David, 2002).
5.9. Son/Cogon Grass (Imperata cylindrica)
Family: Poaceae
5.9.1. Invasion by cogongrass (Imperata cylindrica): A Native to Southeast Asia is a
listed invasive weed in many countries. Cogongrass (Imperata cylindrica) also called Son
is an aggressive, colony forming dense erect perennial grass 1 to 5 feet (30 to 150 cm) in
height. Older infestations will be more difficult to control (Miller, 2003). A Federal listed
noxious weed (Miller, 2003). Cogongrass [Imperata cylindrical (L.) Beauv.] a
rhizomatous perennial grass, is a serious pest in many areas and situations, covering over
500 million acres throughout the world. However, it may be possible to suppress
cogongrass regrowth by introducing native vegetation after initial chemical control
measures have been employed. Also, an understanding of herbicide residues in various
soil types is crucial in the selection of desired native plant species to be incorporated into
this suppression scheme (Macdonald et al., 2003; Mack, 2003).
5.9.2. Description: Cogon grass is an erect, perennial grass. Aggressive,
colony-forming dense perennial grass 1 to 5 feet (30 to 150 cm) in height, often leaning in
mats when over 3 feet (90 cm) in height. Stem Upright to ascending, stout, not -apparent,
and hidden by overlapping leaf sheaths. Stem less tufts of long leaves, blades yellow
green, with off-center midveins and silver-plumed flowers and seeds. Flowers in February
to May Terminal, silky spikelike panicle, 1 to 8 inches (2.5 to 20 cm) long and 0.2 to 1
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inch (0.5 to 2.5 cm) wide, cylindrical and tightly.branched. Spikelets paired, each 0.1 to
0.2 inch (3 to 6 mm) long, obscured by silky to silvery-white hairs to 0.07 inch (1.8 mm).
Seeds in May to June. Oblong brown grain, 0.04 to 0.05 inch (1 to 1.3 mm) long, released
within silvery hairy husks for wind dispersal Culms area mostly erect and unbranched,
with reduced blades and open sheaths (Holm et al., 1977; Bryson and Carter, d1993).
Cogon grass is strongly rhizomatous with extensive, sharply pointed, creeping scaly
rhizomes (Holm et al., 1977).
5.9.3. Taxonomy: The genus Imperata, family Poaceae, subfamily Panicoideae,
supertribeAndropogonodae, tribe Andropogoneae (Gabel, 1982; Watson and Dallwitz,
1992),subtribe Saccharinae, includes nine species worldwide. Hubbard et al. (1944)
recognized five varieties of I. cylindrica worldwide.
5.9.4. Geographical Distribution: Cogon grass has been reported as a weed in 73
countries and on all six countries. It is widely distributed in Africa, Australia, southern
Asia, and the Pacific Islands, and less extensively distributed, or a less serious problem, in
southern Europe, the Mediterranean, the Middle East, Argentina, China, Colombia, the
Caribbean, and the southeastern United States. It has been found at latitiudes from 450N (Japan) to
450S (New Zealand), and from sea level to over 2,000 m elevation (Holm et al., 1977).
5.9.5. Ecology: Grows in full sunlight to partial shade, and, thus, can invade a range
of sites. Often in circular infestations with rapidly growing and branching rhizomes
forming a dense mat to exclude most other vegetation. Aggressively invades
right-of-ways, new forest plantations, open forests, old fields, and pastures. Absent in
areas with frequent tillage. Colonizes by rhizomes and spreads by wind-dispersed seeds
and promoted by burning. Highly flammable and a severe fire hazard, burning extremely
hot especially in winter (Miller, 2003).
5.9.6. Pest status: Cogon grass, Imperate cylindrica (L.) Beauv., has been ranked as
one of the ten worst weeds of the world (Holm et al., 1977). In tropical and subtropical
regions around the globe, this aggressive, rhizomatous perennial is generally considered a
pernicious pest plant due to its ability to successfully disperse, colonize, spread, and
subsequently compete with and displace desirable vegetation and disrupt ecosystems over
a wide range of environmental conditions (Holm et al., 1977; Brook, 1989; Bryson and
Carter, 1993; Dozier et al., 1998).
Son has been reported as a problem in more than 35 annual and perennial crops,
including rubber, coconut, oil palm, coffee, date, tea, citrus, forests, field crops (rice), and
76
row crops (corn) (Holm et al., 1977; Brook, 1989). Problems with Cogon grass often have
arisen on lands cleared of natural forest, which are then quickly colonized by Cogon grass
before cultivation, during plantation establishment and growth, or soon after the
abandonment of land used for short-duration shifting agriculture (Brook, 1989). Left
unchecked, colonized area become densely infested with Cogon grass, are difficult to
convert to other vegetation. Cogon grass infestations damage crops through competition,
causing suppressed growth, reduced yields, and delayed harvests.
5.9.7. Ecological damage: Cogon grass’ tendency to form dense, persistence and
expanding stands allows it to displace other vegetation. Its abundant biomass prevents
recruitment of other plants and changes the properties of the litter and upper soil layers
(Lippincott, 1997). Extensive rhizome reserves of Cogon grass enable it to quickly regrow.
Also, fires induce flowering and seeding, reduce competition from other plants, and
creating opening for seedling establishment (Bryson and Carter, 1993; Dozier et al., 1998).
More than 500 million ha of Cogon grass have been estimated to occur worldwide
(Holm et al., 1977). In Asia, where an estimated 200 million ha are dominated by Cogon
grass, infested areas are increasing at a rate of 150,000 ha annually (Soerjani, 1970).
Cogon grass has invaded a variety of habitats, from highly xeric uplands to fully shaded
mesic sites. Sandhills, flatwoods, hardwwood hammocks, sand dunes, grasslands, river
margins, swamps, scrub and all are invaded by Cogon grass. In addition, Cogon grass can
significantly alter the structure and function of invaded communities (Holm e al., 1977).
5.10. Lantana (Lantana camara)
Family: Verbenaceae
5.10.1. Introduction: Lantana is a land plant, widely grown as an ornamental shrub
throughout the tropics, subtropics and temperate zones, it is established as a weed of
pastures and the environment in ca. 50 countries.
5.10.2. Description: Much branched, thicket forming shrub normally 2-4 m but
capable of becoming a liana up to 15 m tall. Rambling, pubescent perennial shrub,
branched 4 – angled, prickly. Leaves opposite, ternate, strongly smelled. Flowers in
peduncles, cylindrical spikes. Sepal 4-5 toothed calyx, petals 4-5, connate in a cylindric
corolla with slender tube, orange-yellow. Stamens 4. Fruit is a fleshy dry drupe. Flowers
77
all year round, main season autumn to winter. Flowers from white to red with variations in
between, including purple.
5.10.3. Habitat: Along roadside, village thicket, jungles, tea plantation, mixed forest.
Found all over the country.
5.10.4. Reproductive Mode: Year round flowering. Self and cross-pollination. Large
fruit and seed set. Fruit a small drupe with 1 seed. Lantana does not sucker from damaged
or broken roots but will regrow from the base of the stem and from rooted horizontal
stems in contact with moist soil.Concentrates nitrogen in the soil. Produces allopathic
compounds.
5.10.5. Reproductive Output: 24 fruits per inflorescence, 511 inflorescences per
plant, 12,265 fruits per plant (Khanna, 2003).
5.10.6. Medicinal Value: Its leaves have insecticidal properties, used in many skin
diseases. Barks used in rheumatic complications.
5.10.7. Chemical Compounds: Camphor, Sterol, tannin.
5.10.8. General Impacts: Decreased productivity in pastures. Poisons cattle. Invades
disturbed natural ecosystems establishing in open situation creek banks and roadsides.
Excludes understorey species. Changes faunal makeup by providing perch sites and cover.
Understorey competitor for forestry.
5.10.9. Lantana a poisonous plant: Lantana plant poisoning is seen in all grazing
animals, like cattle, sheep, and goats. Lantana plant contains certain hepatic toxins, namely
Lantadene A and B. The former is more toxic that the latter. They can cause liver damage
or degeration resulting in its dysfunction and digestive disturbances. Bile ducts in the
river are also damaged and fibrosed become hard. This can lead to bile retention in the
liver and jaundice or yellowish discoloration of skin and mucous membranes. Jaundice
also induce severe digestive troubles and weakness. Moreover, a photodynamic substance,
namely phyloerythrin is produced from the chlorophyll of lantana plant leaves. This
substance appear in the skin as a photosensetiser. When sun light falls on the skin, it reacts
mostly at the unpigmented parts like muzzle, face, ears leading to local inflammatory
reaction or dermatitis. These changes are followed by secondary bacterial infections and
diseases. Death is due to liver damage and severe weakness clubbed with jaundice, skin
damage and concomitant diseases.
78
Lantana poisoning is of two types, on is acute and the other chronic. Acute form is
seen when animals consume large amounts of it and chronic when they take small
amounts for longer periods. In acute form, animals suddenly become dull and depressed.
They refuse food. There is dysentery followed by marked dullness and paralysis of legs.
Death may supervene, when they are not treated specifically for it. In chronic form,
animals become slowly dull and morosed. There are excessive salivation and yellowish
discoloration of skin and mucous membranes(Christopher, 2001).
5.10.10. Control: Control must be integrated, including manual removal, burning,
shading, chemical control and revegetation. In many cases natural restoration is difficult
after removal of thickets, due to reduced seed banks of native species. Long history of
international biological control, however few are effective to date (Khanna, 2003).
5.11. Assamlata (Mikania cordata) Family: Compositae
5.11.1. Description: Twining, strongly branched climber with limited life-span, 5-
10m long, stem slender, younger parts finely pubescent. Leaves opposite, ovate to ovate
triangular with deeply cordate base, acuminate apex, slightly dentate. Flowers 4.5-6 mm
long, numerous, peduncled, in axillary or terminal, dense coryms. Corolla white,
campanulate. Fruits, achenes blackish brown. Flowers mostly during dry season.
5.11.2. Habitat: Forest, wasteland, agricultural land, roadside, plantation, jungle.
Found in the Sylhet and Chittagong Hill Tract regions. The climber also grows in many
other countries.
5.11.3. Medicinal Value: Rich source of vitamins A, B and C. Leaves used against
snake bites. It has also bitter substances and tannin.
5.11.4. Ecological threat: Mikania cordata has become a serious problem in
Bangladesh, India, Srilanka, Thailand, Phillippines, Mauritius, Malayasia, Indonesia, and
many of the pacific islands. Once established, the plant becomes rampant and covers other
plants. It then suppresses other plants by cutting out the light and smothering them.
Though many plants are damaged by Mikania cordata some plants can grow with it. These
include Ageratum conyzoides Lantana camara etc. Mikania cordata ‘s harm is
unquestionable and it is an urgent but difficult task to control the plant.
79
Aquatic invasive plants: Literature on two aquatic plants of Bangladesh, Water
Hyacinth (Eichhornia crassipes) and Waterlettuce (Pistia stratiotes) has been given
below:
5.12. Water Hyacinth (Eichhornia crassipes)
Family Pontederiaceae
5.12.1. Introduction: Waterhyacinth is one of the world’s worst aquatic invasive
weeds. It is one of the worlds 100 most invasive plants.
5.12.2. Description: Waterhyacinth is an erect, free-floating, stoloniferous, perennial
herb. The bouyant leaves vary in size and morphology. The short, bulbous leaf petioles
produced in uncrowded conditions provide a stable platform for vertical growth. Plants in
crowded conditions from elongate (up to 1.5 m) petioles (Center and Spencer, 1981).
Leaves are arranged in whorls of six to 10, and individual plants develop into clones of
attached rosettes (Center and Spencer, 1981). Seed capsules normally contain fewer than
50 seeds each (Barret, 1980). Each inflorescence can produce more than 3,000 seeds and a
single rosette can produce several inflorescences each year (Barrett, 1980). The submerged
roots (rhizoids) are relatively long and "feathery", extending as much as 1 m below the water.
The small long-lived seeds sink and remain viable in sediments for 15 to 20 years
(Matthews, 1967; Gopal, 1987). Seeds germinate on moist sediments or in warm shallow
water (Haigh, 1936; Hitchcock e al., 1950) and flowering can occur 10 to 15 weeks
thereafter (Barrett, 1980). Populations increase mainly by vegetative means.
5.12.3. Taxonomy: Waterhyacinth is the standardized spelling adopted by the Weed
Science Society of America (WSSA, 1984) to denote that it is not an aquatic relative of
true “hyacinth” (Hyacinthus spp.), as the two-word spelling suggests. The taxonomic
placement of Waterhyacinth, based on Cronquist (1988), Thorne (1992), and Takhtajan
(1997), is as follows: division Commelinidae (Liliidae [Cronquist, 1988; Thorne, 1992];
superorder Commelinance (Thorne, 1992), order Pontederiales (Liliales [Cronquist, 1988];
philydrales [Thorne, 1992]); family Pontederiaceae, genus Eichhormia; specific epithet
crassipes (Martius) Solms-Laubach.
5.12.4. Distribution: This South American native is one of the worst aquatic weeds in
the world it is now found in more than 50 countries on five continents (IUCN, 2003)
80
5.12.5. Pest status of weed: Waterhyacinth, Eichhormia crassipes (Mart.) Solms.-
Laubach, is considered one of the world’s worst weeds (Holm et al., 1977), invading lakes,
ponds, canals, and rivers. It was introduced into many countries during the late 19th and
early 20th centuries, where it spread and degraded aquatic ecosystems. It is still rapidly
spreading, where new infestations are creating life-threatening situations as well as
environmental and cultural upheaval (Cock et al., 2000).
5.12.6. Economic Damage: The costs of water hyacinth invasion are often in millions
of dollars and its control is expensive and time-consuming. Waterhyacinth grows rapidly
(Penfound and Earle, 1948) forming expansive colonies of tall, interwoven floating plants.
Water hyacinth is a very fast growing plant, with populations known to double in as little
as 12 days (IUCN, 2003). E. crassipes can form small colonies, "floating islands" or
extensive mats that can cover thousands of hectares of previously open water It blankets
large waterbodies, creating impenetrable barriers and obstructing navigation (Gowanloch
and Bajkov, 1948; Zeiger, 1962). Floating mats block drainage, causing flooding or
preventing subsidence of floodwaters. Large rafts accumulate where water channels
narrow, sometimes causing bridges to collapse. Waterhyacinth hinders irrigation by
impeding water flow, by clogging irrigation pumps, and by interfering with weirs
(Penfound and Earle, 1948). Multimillion-dollar flood control and water supply projects
can be rendered useless by waterhyacinth infestations (Gowanloch and Bajkov, 1948).
Infestations block access to recreational areas and decrease waterfront property values, oftentimes
harming the economies of communities that depend upon fishing and water sports for revenue.
Shifting waterhyacinth mats sometimes prevents boats from reaching shore, trapping the occupants
and exposing them to environmental hazards (Gowanloch and Bajkov, 1948; Harley, 1990).
Waterhyacinth infestations intensify mosquito problems by hindering insecticide applications,
interfering with predators, increasing habitat for species that attach to plants, and impeding runoff
and water circulation (Seabrook, 1962). The hyacinth also increases evapotranspiration well above
that of open water and causes significant water loss to reservoirs and wild waters. The crowding of
plants at the edges of water bodies prevents peoples' access to the water for, e.g., collecting water
and fishing as well as access of fishing boats. While widespread, it tends only to become invasive
when there is some alteration to a water system.
5.12.7. Ecological damage: Ecological studies carried out to assess Eichhornia crassipes’s
impact on the phytoplankton community diversity established that it has serious ecological
consequence on the phytoplankton community assemblage and caused drastic reduction on the
diversity and density. Phytoplanktons play a key role in wastewater purification process (Otieno,
2003). Water hyacinth prevents sunlight and oxygen from reaching the water column and
81
submerged plants. Its shading and crowding of native aquatic plants dramatically reduces
biological diversity in aquatic ecosystems (IUCN, 2003). When invasive, water hyacinth forms a
complete covering of the water surface that excludes most light and air for submerged organisms
thus depriving them of essentials for survival Dense mats reduce light to submerged plants, thus
depleting oxygen in aquatic communities (Ultsch, 1973). The resultant lack of phytoplankton
(McVea and Boyd, 1975) alters the composition of invertebrate communities (O’Hara, 1967;
Hansen et al., 1971), ultimately affecting fisheries. Drafting mats scour vegetation, destroying
native plants and wildlife habitat. Waterhyacinth also competes with other plants, often displacing
wildlife forage and habitat (Gowanloch, 1944). Higher sediment loading occurs under
Waterhyacinth mats due to increased detrital production and siltation. Herbicidal treatment or
mechanical harvesting of Waterhyacinth often damage nearby desirable vegetation. Holm et al.
(1969) ascribed losses of $43 million in 1956 to Waterhyacinth infestations in Florida, Mississippi,
Alabama, and Louisiana.
5.12.8. Management or Control: Water hyacinth can be controlled by mechanical means
(using manpower and machines) but this is mostly unsuccessful as the plant grows faster than
mechanical clearance can keep up with. Various herbicides are effective but have significant risks
for other wetland biodiversity. Most successful and self-sustaining is biological control using two
beetles (the weevils Neochetina eichorniae and N. bruchi) and other species such as a moth, a mite
and pathogenic fungi. Biocontrol alone, however, is not always effective and there are often good
reasons for using integrated control involving mechanical and chemical control as well (IUCN,
2003).
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Fig: Eichhornea/Pistia
5.13. Waterlettuce (Pistia stratiotes)
Family: Araceae
5.13.1. Introduction: Waterlettuce is among the world’s worst weeds (Holm et al.,
1977). It is one of the worlds 100 most invasive plants.
5.13.2. Description: Waterlettuce is a perennial herb in the aroid family (Araceae).
The plant consists of free-floating rosettes of many leaves. The rosettes occur singly or
connected by short stolons. Leaves are gray-green, densely pubescent, and wedge shaped
(obovate-cu-neate). They have conspicuous parallel veins. Roots are numerous and
feathery. The inflorescences pale-green spathes near the center of the rosette. Pistia is a
monotypic in the subfamily Aroideae (Grayum, 1990). The rosettes are perennial along
the Gulf Coast, but act as annuals in more temperate zones. Population expansion is
83
primarily by vegetative propagation. It reproduces through flowers and seeds (which can
remain viable for up to 15 years) and by vegetative propagation from its stolons.
Flowering occurs year-round but peaks during summer and early autumn. Plants may be
found floating singly or in small groups or large mats - on open water or partly" stranded"
on the margins of a water body or wetland.
5.13.3. Origin: Widespread in the tropics and sub-tropics but probably originating in
South America; some authors suggest that it is native to Africa, others that it has become
"naturalised". Nevertheless it can become invasive in the true sense of that word. (IUCN, 2003)
5.13.4. Habitat: P. stratiotes is found in ponds, dams, lakes, rivers and a range of
permanent and seasonal wetlands. It often grows and expands in pools and wetlands
associated with river systems and then is released into the main river channel when the
river rises in its flood season.
5.13.5. Pathway: Water lettuce is spread along water systems by flow and wind and
can be moved by aquatic animals (hippos, other marsh mammals, waterbirds) and human
visitors to infested waters. Pistia is also moved on boats and wheeled vehicles that have
come into contact with infested waters (IUCN, 2003). It is widespread in Bangladeshi
water systems at relatively low density but can grow quickly and form mats when the
necessary nutrients are available - and in this way can become invasive
Pest status of weed: It forms extensive mats capable of blocking navigational
channels, impeding water flow in irrigation and flood control canals, and disrupting
submersed animal and plant communities (Bruner, 1982; Sharma, 1984). Water lettuce
can accumulate at barriers in flowing water and cause damage or blockage to, e.g.,
irrigation canals and inlets to hydropower installations.
5.13.6. Nature of Damage:
The economic costs associated with such damage have not been quantified. Indirect
losses accrue when large floating mats interfere with recreational activities such as boating
and fishing, but these have not been quantified. Also, several species of mosquitoes that
breed on Waterlettuce are important vectors of malaria, encephalitis, and filariae
(Lounibos and Dewald, 1989; Lounibos et al., 1990). Equine encephalitis, also vectored by
mosquitoes associated with Waterlettuce. Costs associated with these diseases are
unknown and the protin of mosquito control operations directed toward Waterlettuce-
borne mosquitoes has not been reported.
84
5.13.7. Ecological damage: It can grow together with Water Hyacinth and Salvinia to
worsen the effects of both. There are reports of deleterious ecological impacts associated
with P. stratiotes infestations and these studies have generally been limited in scope.
Sculthorpe (1967), for instance, noted that the intertwined root systems (composed of long
adventitious roots arrayed with copious lateral rootlets) of extensive infestations accelerate
siltation rates as they slow water velocities in rivers and streams. The resultant degradation
of benthic substrates under these infestations has never been studied directly, but
accelerated siltation often renders the affected benthos unsuitable as nesting sites for
various fish species (Beumer, 1980) and as macroinvertebrate habitat (Roback, 1974). The
accumulation of Waterlettuce-generated detritus under large infestations only adds to this
problem, and likely increases sediment and nutrient loadings much as it does under
waterhyacinth mats (Schmitz et al., 1993). Furthermore, Sridhar (1986) reports that
Waterlettuce can bioaccumulate considerable amounts of heavy metals, so the detritus
under some mats could be toxic. The waters under dense Waterlettuce populations in lakes
can become thermally stratified (Sculthorpe, 1967; Attionu, 1976), with dissolved oxygen
levels and increased alkalinity (Yount, 1963; Attionu, 1976; Sridhar and Sharma, 1985).
Prolonged oxygen deficits reduce plankton abundance (Hutchinson, 1975) and cause
increased morality of fish (Ayles and Baricaa, 1977; Clady, 1977) and macrovertebrates
(Roback, 1974; Cole, 1979). Summary can be written as:
Water-lettuce mats can lower dissolved oxygen concentrations reducing aquatic
life.
Dense populations may lower water levels because water-lettuce increases
evaporation rates over open water areas.
Water-lettuce mats can restrict water flow increasing flooding along rivers and
canals.
Dense water-lettuce populations produce ideal breeding environments for
mosquitoes.
Water-lettuce populations crowd out native plants and animals (lowers
biodiversity).
Water-lettuce populations often form large expanses of dense, impenetrable
floating mats limiting boat traffic, recreation, flood control, and wildlife use. These dense
canopies at the water surface shade out native submersed plant species and can uproot
native emergent plants that are important to wildlife. P. stratiotes can form thick and
extensive mats that can block both sunlight and air from reaching a water surface and so
have impacts on aquatic biodiversity and fisheries.
85
5.13.8. Management/Control: Pistia can be controlled by the mechanical removal of
plants - but care must be taken that they are not re-introduced to the water system.
Chemical control has been used and 2-4 D, a herbicide is quite effective - except for the
obvious impacts on non-target species in wetlands and water bodies. Biological control
using beetles (especially the weevil Neohydronomous affinis) has been effective in tropical
situations. As with other floating aquatic weeds, however,care taken with the watershed to
reduce nutrient input to wetlands is the most effective method of control -a I t h o u g h
expensive and not always possible. (IUCN, 2003)
Chapter 6: Control and management
of IAS.
6.1 Control of invasive plants.
Biological invasions pose a huge nationwide and worldwide problem that urgently
needs innovative approaches toward solutions (Philip and Lloyd, 2001). Indeed, no
agency can hope to rid their lands of hundreds of years of nonnative introductions
(Akerson, 2003). In response to the expanding ranges of and increasing damage caused by
alien species, the control of invasive alien species has become a priority for environmental
management and an integral component of many habitat conservation efforts. Alien
species damage native species and ecosystems on a global scale. Thus, to prevent further
loss of biological diversity, we need to study and control the spread of alien species as
quickly as possible. Most alien species have not been sufficiently investigated with respect
to effective countermeasures to prevent their intrusion and expansion (Primack & Kobori,
1997). In order to take prompt measures against ecological problems of invasive alien
species (IAS), we have to own jointly biological data, which indicate the IAS species
identification, the origin of the IAS, the process of invasion of the IAS, and the ecological
impact caused by the IAS (Koich et al. 2004)
Invasive plants pose a major threat to the productivity and sustainability of
agricultural, managed and natural ecosystems. Thus, invasive plants are biological
86
pollutants within infested ecosystems. Unlike chemical pollutants that diminish over time,
biological pollutants have the ability to grow adept, reproduce and spread, unless
mitigated.
6.1.1. Control methods can include the following or a combination of all
four:
6.1.1.1 Chemical control:(using pesticides) can be effectively used to destroy
invasive species, but it can be problematic due to impacts on non-target organisms
(including humans), the development of resistance, and expense,
6.1.1.2 Physical/ Mechanical control: Means either hand pulling or temporarily
changing the environment to control invasive weeds. Temporary environmental changes
include reducing light with dyes, dewatering in the water to freeze, dry, then burn plants,
and flooding to shade underwater plants or flush floating plants out of the water body
(Anon, 2003). Physically removing the invasive species is often successful, but can be
expensive and labor intensive. Depending on the types of plants and conditions, many
different kinds of machines cut, chop, shred, slurry, press, transport, and remove invasive
aquatic weeds.
6.1.1.3 Biological control:(introducing a natural enemy-predator, parasite, or
disease-often from the pest’s native range) can be an environmentally sound way to
control invasive species with minimal expense, but some control agents do not survive and
others attack non-target organisms, i.e., become invasive themselves.
6.1.2. Prevention: Clearly, The best way to limit impacts of nonnative species is to
prevent them from invading and becoming established in a new area. Prevention is the best
deterrent against invasive plants. However, it is difficult to know if a species will become
a problem in a given locality and we often don't know why some species become invasive.
Sometimes species don’t pose problems until years after they’ve been in an area.
Complete removal may be feasible early in an invasion or in a restricted area, but more
often control or containment is the only practical way to limit ecological or economic
damage, especially for species that have already invaded large areas. Once established,
successful eradication or management is contingent upon early detection, identification,
assessment, development of eradication strategies and a steadfast implementation of that
strategy. Recognition of need, desire to succeed, and the willingness to persist, are key
elements of success. The most effective way to reduce invasive weed problems is to
prevent their introduction. This is much more difficult than it may seem. It is difficult to
87
predict which may become problems before they are brought into the Bangladesh. When
freed from these controls, some plants thrive and become invasive weeds in their new
surroundings. One can help prevent problems by never putting aquarium plants in lakes,
rivers, or wetlands.
6.1.3. Eradication: The eradication or successful containment and management of an
invasive plant requires a logical process to succeed. 5 fundamental steps of this process
are: 1) Recognition of need; 2) Discussion among stakeholders; 3) Development of
strategies and a course of action; 4) Development of methodology; 5) Improvements as
needed. Implementation of these seven fundamental steps, along with common sense and
persistence, will lead to a successful program (Eplee, 2003). The Witchweed eradication
Program [Striga asiatica (L.) O. Kuntze] that was initiated in the Carolinas in 1958 is a
Fig: Eichhornea crassipes(eradication)
88
case study in the successful eradication of an alien, invasive plant. This federal – state
cooperative effort utilized the seven elements of successful program implementation. After
the program began, it took nearly 20 years to develop the strategies and science based
methodologies to effectively deal with this invasive plant.
When prevention fails, eradication of invasive plants becomes the second best
alternative to control invasive plants. Most of the invasive herbs and shrubs like Lantana
camara, Eupatorium odoratum, Ipomea carnea, Mikania cordata, Ageratum conyzoides,
Imperata cylindrica, Eichhornea crassipes, Pistia stratiotes, etc. are physically eradicated
by the farmers in Bangladesh.
6.1.3.1. Criteria to be satisfied to achieve Eradication:
Shine et al. (2000) gave some conditions to be satisfied to Achieve Eradication which are
as follows:
a. The rate of population increase should be negative at all densities. At very low
densities it becomes progressively more difficult and costly to locate and remove
the last few individuals.
b. Immigration must be zero. This is usually only possible for offshore or oceanic
islands, or for very new alien invasions.
89
c. All individuals in the population must be at risk to the eradication technique(s) in
use.
d. The survival of seed banks in the soil should be checked.
e. Adequate funds and commitment must continuously exist to complete the
eradication over the time required. Monitoring must be funded after eradication is
believed to have been achieved until there is no reasonable doubt of the outcome.
f. The socio-political environment must be supportive throughout the eradication
effort. Objections should be discussed and resolved, as far as practicable,
before-the eradication begun.
6.1.4. Early Detection and Rapid Response:
Once invasive weeds become widely dispersed within a water body or across a
large region, eradicating them becomes difficult and often impossible. Ecosystem
managers/Foresters should frequently inspect lands/waters for known invasive weeds and
to find plants that do not seem to belong. When invasive weeds are discovered,
management programs must begin immediately to reduce environmental damage and
economic costs.
6.1.5. Slowing the spread: Invasive species spread in many ways, often helped
unintentionally by people. One can slow the spread of invasive species, and prevent new
invasions, by being an aware, responsible and vocal steward of one’s own property.
Scout for invasive plants: we have to learn which plants and animals are problems
in Bangladesh, so they can be recognize if they are see them.
Remove invasive plants before they become a problem: The best way to control
invasives is through early detection and rapid response. we should pull, cut, spray
or deadhead problem plants before they go to seed.
Avoid introducing invasive plants: Checking with plant sellers home and abroad
before buying plants can be made, to make sure that the plant wanted, whether
native or exotic, is not invasive.
90
Avoid transporting invasive plants: Seeds of invasive plants are easily moved from
place to place on hiking boots, car tires, pants cuffs, and camping or recreational
gear, especially when entering wildlands or other natural areas, or new bodies of
water. We should not bring species into Bangladesh from distant parts of the
world.
Minimize disturbance: Many invasive plants, are adapted to disturbance and
rapidly take over newly disturbed areas. We should monitor disturbed areas for
species that spread quickly.
Spread the word: we should Spread the word Invasive plants that have
environmental, economic and social impacts for all of us to the common people,
appropriate state government agencies and conservation groups (Anon, 2003).
6.2. Control of invasive aquatic weeds:
Because water is so important to our survival, scientists and ecosystem managers
continually search for additional and more effective ways to control invasive aquatic
weeds while preserving native plants and animals and protecting human health and
property. Invasive aquatic weed control methods fit into any of the four basic categories
described earlier:
Aquatic plant managers combine, or integrate, (Integrated plant management) as
many different methods as possible to control invasive weeds. There is to reduce problems
from invasive weeds and improve conditions for native plants and animals using the
control methods that are best suited to conditions in and surrounding each water body.
Water hyacinth control is a good example of integrated plant management. Several insects
and diseases feed only on water hyacinth reducing plant size and the amount of seeds it
produces. This reduces the amount, and also the cost, of herbicides needed to control water
hyacinth. Mechanical harvesters remove water hyacinth from small areas where herbicides
are not practical or if immediate removal is needed like dams and bridges. Sometimes,
water hyacinth is piled up by picking and allowed to rot or burnt when dried.
91
6.3. The strategy of managing exotic invasive plants:
The goals of alien species management include eradication, control and
confinement however; the first is the ideal solution (Nobuo and Mick, 2004). The invasion
of exotic plants is a severe problem due to its tremendous damage and impact. The
management and assessments of exotic plants are so very important. In fact, introduced
species are a greater threat to native biodiversity than pollution, harvest, and disease
combined (Pokorny et al., 2003). Thus, the practical and effective ways and means of
stopping or reducing invasions are in an urgent need.
Mechanical methods are only used at the starting of invasion or small number of
non- native species appearing.
Chemical means can cause new environmental problem that can bring new
pollution and threats to other native species.
Biological control is the science and technology of controlling pests and other
dangerous species by using natural enemies. There have been many successful cases in the
field of using biocontrol. However, biocontrol is not a panacea. Without careful use, it can
produce threats to non-target species. This indicates that a more thorough screening
biocontrol agents for non- native species should have preceded the release of these agents
(Wang and Meijuan, 2003).
To manage non-indigenous plant invasions, mechanisms of invasion resistance
must be identified and modified as a portion of management. One mechanism is that
functionally diverse plant assemblages use resources more completely. Study suggested
that establishing and maintaining a diversity of plant functional groups within the
community enhances resistance to invasion (Pokorny et al., 2003). A generalized objective
for invasive plant management is to establish and maintain invasion resistant plant
communities that meet other land-use objectives. Establishing and maintaining diverse,
weed resistant plant communities must be a major goal of all integrated weed management
programs (Pokorny et al., 2003).
Successful management of invasive plants requires active attempts to prevent new
introductions, vigilant detection of nascent populations, and persistent efforts to control
and eradicate the worst exotic weeds. To achieve these objectives, Rejmanek, (2003) gave
five groups of complementary approaches. (1) Stochastic approaches allow probabilistic
92
predictions about potential invaders based on initial population size, residence time, and
number of introduction attempts. (2) Empirical taxon-specific approaches are based on
previously documented invasions of particular taxa. (3) Evaluations of the biological
characters of non-invasive taxa vs. those of successful invaders give rise to both general
and habitat-specific screening procedures. (4) Evaluation of environmental compatibility
helps to predict whether a particular plant taxon can invade specific habitats. Finally, (5)
experimental approaches attempt to tease apart intrinsic and extrinsic factors underlying
invasion success. An emerging theory of seed plant invasiveness based on biological
characters has resulted in several rather robust predictions. Population fitness homeostasis,
as a result of both individual fitness homeostasis and population genetic polymorphism, is
a general prerequisite invasiveness over a range of environments. While several characters
linked to reproduction and dispersal are best predictors of invasiveness disturbed habitats,
competitiveness for limiting resources promotes invasiveness in natural and semi-natural
ecosystems (Rejmanek, 2003).
Invasive plants impede grassland restoration by disrupting ecosystem processes.
Managing invasive plants requires manipulating disturbance regimes that favor desirable
species and wanted changes in successional trajectories. Reasons for the arrival,
establishment and spread of invasive plants should be understood before effective
grassland restoration strategies are developed. Removing an invasive plant species without
attention to plant community dynamics often only opens niches for other undesirable
species to occupy. The suitability of weed control tools (biological, chemical, mechanical
and cultural) will vary according to the invasive plant and
invaded site characteristics (Masters and Daniel, 2003).
For invasive plant control to be effective, citizen involvement is key. Linking local
issues with parallel regional, national and global ones can accomplish this task. The broad
need to conserve native biodiversity worldwide should be articulated to a specific
community in local terms, with local issues, such as controlling Kachuripana (Eichhornea
crassipes). To truly arouse human interests and meet human needs, successful
demonstration projects should be implemented and marketed so that individuals can
physically see how the recreational experience improves in absence of adjacent
monocultures and how property values rise where a diversity of native species have
regenerated (Sewak and Kylie, 2003).
93
Once the invasive species have been controlled or eliminated, ecosystems may
need to be restored to return lost components or functions to degraded areas. Restoring
native communities is an important step to minimize the chances an area will be
reinvaded.
94
Part 3: Field observations
Chapter 7: Materials and Method
7.1. Materials and Method:
7.1.1 Collection of information: Literatures were collected from the
published books, journals, weeklies, thesis and review papers or other scientific writings
from the libraries of different universities and research Institutions. Internet was one of the
important sources of literature. Consultation was made to the experts (Botanists,
Silviculturists, Zoologists, Foresters) of various Institutes and informations were written
down. Related information were also collected form various Project experts of various
agencies like Forest Department, IUCN, UNEP etc. working for the conservation of
Biodiversity in Bangladesh.
7.1.2. Method applied: The research work method included taking of 2m by
2m sample plots randomly one under alien species (Acacia auriculiformis, Eucalyptus
camaldulensis and Melaleuca leucadendron) and another under adjacent indigenous trees,
separately for each of these three trees, whatsoever indigenous trees are present very close
to the alien species plantation. Each of these two sample plots formed 1 replication. There
were 4 replications taken for each alien species in different part of Chittagong and Sylhet.
Name (scientific or local or both), total no and average height of the undergrowth plants
were taken from adjacent random sample plants of 2m by 2m size under alien trees and
nearby indigenous trees separately. Careful selection of the site was made where there
exist both alien and indigenous trees in nearby plantation. In the hills sample plots under
alien trees and nearby indigenous trees were selected taken at similar slope, altitude and
aspect. 4 replications were taken for each invasive tree species, 3 in Chittagong and 1 in
Sylhet. Each replication included 2 sample plots one under alien tree and another under
indigenous trees.
For Lantana camara, Eupatorium odoratum, Mikania cordata, and Ipomea carnea,
2m by 2m sample plots were taken and the plants growing with them in close association
or contiguous to the invasive plants were noted down. Growth of these species was
95
measured from periodic evaluation from the sample plots that were guarded in wild
condition in Chittagong and Sylhet. Their impact on nearby plants was observed by
visiting different localities of Bangladesh.
The samples that could not be identified instantly was collected and later taken to
the experts for identification and properly identified by their local name, scientific name,
and family they belong to.
The spread or distribution of the invasive plants was estimated through physical
visit to different localities in Bangladesh. Photographs of invasive plants species were also
taken.
7.1.3. Materials used: Sunto clinometer was used to measure the height of the
trees, slope and altitude of the sample plots. Diameter tape was used for diameter
measurement of the trees. Measuring tape was used to fix the sample size in the field.
Wooden scale of 1m height graduated in cm was used to measure the undergrowth height
and growth. For undergrowth vines e.g. Alulata, Asamlata etc, their length, horizontal or
vertical, has been considered as height in this literature
7.1.4. Compilation of data: Finally all the data was compiled to generate
information and the thesis was written down.
96
7.2. Rationale of the method applied in this research work:
In attempting to assess the direct effects of invasive plants on local native species
diversity, the easiest way to interpret the effect would be experimental introductions of
alien plants into native communities. But an alternative experimental approach to
assessing the impacts of invaders on native plant diversity is to physically remove alien
vegetation from a site and quantify changes in diversity that follow but is very labor
intensive. Easiest quantitative evidence for the loss of biodiversity due to invasive plants
comes from paired community surveys, where native species abundance, richness or
diversity is compared between invaded and a neighboring univaded areas. (Holms and
Cowling, 1997a; D’Antonio et al., 1998)
The latest methodology was applied in this work. The research method applied to
assess the impact of invasive plants on native plant biodiversity in Bangladesh included
taking of 2m by 2m sample plots randomly one under alien species (Acacia auriculiformis,
Eucalyptus camaldulensis and Melaleuca leucodendron) and another under adjacent
indigenous trees, whatever indigenous trees are present very close to the invasive species
plantation. Each of these two sample plots formed one replication. The sample plots in
each replication were not wide apart. In most of the cases, they were on average within 15
m apart. The shorter distance of sample plots are expected to eliminate the experimental
error roughly. All sample plots of each replication are selected carefully so that they
belong to the same slope, altitude and aspect of the slope to reduce the microclimate effect
on the growth of the ground vegetation. Nutrient status, microbial effect, biotic effects etc
on the growth of vegetation of each sample plot were considered negligible or similarly
effected. The vegetation structure and undergrowth were considered only be affected by
alien and indigenous trees.
97
Chapter 8: Result and
Discussion
8.1. Data of the sample plots in Acacia auriculiformis,
Eucalyptus Camalsulensis, and Melaleuca leucodendron
plantations.
8.1.1. Sample plots in Acacia auriculiformis and indigenous trees
plantations:
Replication 1:
Location: Lower hill slope in front of the administrative building of the Institute of
forestry and environmental sciences, Chittagong University.
Slope: 24%
Altitude: 2m from the ground level.
Spacing: For both Acacia auriculiformis and indigenous species is 2mx2m
Age: 11 years for both Acacia auriculiformis and indigenous trees plantation.
Distance: between the sample plots of Acacia auriculiformis and indigenous trees
plantation is 9m.
Average height of Acacia auriculiformis: 12m
Average diameter of Acacia auriculiformis: 11.5cm
Average height of indigenous trees (Telsur- Hopea odorata and Chickrassy- Chickrassia
tabularis): 10m
Average diameter of indigenous trees: 8.5cm
Table 3: Name of the plant species found in the sample plots under Acacia
auriculiformis and indigenous trees with their total number and average
height in replication 1.
Species name
Under Acacia
auriculiformis
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht
(c m)
Total
no
Avg
ht
(cm)
Ageratum conyzoides Compositae ** ** 3 23
98
Derris spp Leguminosae ** ** 2 56
Polygonum spp ** ** 11 48
Aal gash 45 27 48 27
Apang Nelsonia spp Acanthaceae 4 57 6 27
Arkila Ixora nigricans Rubiaceae 6 45 6 45
Arshogonda Withania somnifera ** ** 1 22
Asamgash Eupatorium odoratum Compositae 1 25 3 25
Bash ghass Graminae ** ** 3 86
Chotrapata Flaria interapta Articaceae 4 8 5 8
Golboroi/
Jongliboroi
** ** 2 53
Kaispata Dalbergia stipularis Leguminosae 5 47 8 47
Sample -1 3 54 ** **
Sample -2 1 56 2 50
Toynlata Jasminum spp Oliceea 5 72 6 72
Vitex Clerodendrum viscosum Verbenaceae 1 15 3 15
** Indicates that the species is absent to that plot.
Replication 2:
Location: Mid hill slope at the back of the under construction auditorium of Shahjalal
University of Science and Technology, Sylhet.
Slope: 35%
Altitude: 5m from the ground level.
Spacing: 2mx2m for both Acacia auriculiformis and indigenous species
Age: 16 years for both Acacia auriculiformis and indigenous trees plantation.
Distance: between the sample plots of Acacia auriculiformis and indigenous trees
plantation is 9m.
Average height of Acacia auriculiformis: 18m
Average diameter of Acacia auriculiformis: 16.5cm
Average height of indigenous trees (Chapalish- Artocarpus chaplasha, Arjun- Terminalia
arjuna and others): 15m
Average diameter of indigenous trees: 16.2cm
99
Table 4: Name of the plant species found in the sample plots under Acacia
auriculiformis and indigenous trees with their total number and average
height in replication 2
Species name
Under Acacia
auriculiformis
Under Indigenous
tree
Local
Name
Scientific Name Family
Total
no
Avg.
ht
(c m)
Total
no
Avg
ht
(cm)
Borreria articulark Rubiaceae 2 63 2 61
Commelina spp. Commelinaceae 5 48 6 51
Ichnocarpus frutescens
Apocynaceae 5 38 5 42
Polygonum spp 3 40 3 53
Achargash Microcos paniculata Tiliaceae 1 60 1 60
Bas gassh Graminae 1 45 1 45
Ghuruchea Combritum spp Combretacea 8 50 8 50
Gulboroi/Jo
ngli boroi
Zizyphus oenoplea Rhamnaceae 1 15 1 15
Kaispata Dalbergia stipularis Leguminosae 2 40 2 40
Putijam Syzygium cumini Myrtaceae 2 45 2 45
Sample 1 3 25 3 25
Sample-3 2 45 2 49
Ulu son Saccharum
spontaneum
Cramineae 15 65 18 71
Umberalla
Boewia spp. 1 72 1 58
Vitex Clerodendrum
viscosum
Verbenaceae 2 32 2 32
Zongli
jumka/Jumkalata
Passiflora foetida Passifloraceae 1 120 2 116
Piper
boehmerifolium
Piperaceae ** ** 1 35
Khosh khoshia lata Byttneria pillosa Sterculiaceae ** ** 2 90
Muschanilata Stephania
harnendifolia
Menispermaceae ** ** 1 75
100
Sample-4 ** ** 1 35
** Indicates that the species is absent to that plot.
Replication 3:
Location: Chittagong University Campus. Mid hill slope near the Social Science
Building.
Slope: 42%
Altitude: 6m from the ground level.
Spacing: 1.5mx1.5m for both Acacia auriculiformis and indigenous species
Age: 15 years for both Acacia auriculiformis and indigenous trees plantation.
Distance: between the sample plots of Acacia auriculiformis and indigenous trees
plantation is 8m.
Average height of Acacia auriculiformis: 16m
Average diameter of Acacia auriculiformis: 17cm
Average height of indigenous trees (Gargan -Dipterocarpus turbinatus and Gamar -
Gmelina arborea, Pitraj -Aphanamixis polystachya): 14.5m
Average diameter of indigenous trees: 15.2cm
Table 5: Name of the plant species found in the sample plots under Acacia
auriculiformis and indigenous trees with their total number and average
height in replication 3.
Species name
Under Acacia
auriculiformis Under Indigenous
tree
Local Name Scientific Name Family
Total
no
Avg.
ht
(c m)
Total
no
Avg
ht
(cm)
Achargash Microcos paniculata Tiliaceae 3 65 4 110
Alulata Dioscorea alata
Discoriaceae 2 100 2 300
Arkila Ixora nigricans Rubiaceae 5 63 8 20
Asamgash Eupatorium odoratum Compositae ** ** 4 15
Bashker 40 35
Batna Quercus spicata ** ** 5 100
Dumur Ficus hispida Moraceae ** ** 1 62
101
Ghuruchea Combritum spp Combretacea 6 80 12 130
Gulboroi/Jongli
boroi
Zizyphus
oenoplea
Rhamnaceae 1 25 ** **
Hara ** ** 1 400
Horina
/Horinna Gota
Vitex
peduncularis
Verbenaceae ** ** 3 90
Jharugash Thysaenolena
maxima
Poaceae 8 90 ** **
Kaispata Dalbergia stipularis Leguminosae ** ** 4 60
Khosh khoshia lata Byttneria pillosa Sterculiaceae 1 45 ** **
Lantana Lantana camara Verbenaceae ** ** 7 110
Maittalata ** ** 1 80
Malastoma /Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 2 100 4 80
Putijam Syzygium cumini Myrtaceae 1 15 1 150
Sample 1 ** ** 5 150
Sample 2 1 36
Sample 2 ** ** ** **
Sercuti Phyllanthus spp. Euphorbiaceae ** ** 1 120
Shialkata Cnicus arvensis Compositae ** ** 1 350
Tagar Tabernaemontana
divericata
Apocynaceae ** ** 1 90
Vitex Clerodendrum viscosum Verbenaceae 4 70 4 100
** Indicates that the species is absent to that plot.
Replication 4:
Location: Chittagong University Campus. Mid hill slope near the security office.
Slope: 20%
Altitude: 4m from the ground level.
Spacing: 2mx2m for both Acacia auriculiformis and indigenous species
Age: 14 years for both Acacia auriculiformis and indigenous trees plantation.
102
Distance: between the sample plots of Acacia auriculiformis and indigenous trees
plantation is 8m.
Average height of Acacia auriculiformis: 15m
Average diameter of Acacia auriculiformis: 16.5cm
Average height of indigenous trees (Jarul -Lagerstroemia speciosa,Gargan -Dipterocarpus
turbinatus, Chapalish- Artocarpus chaplasha): 13m
Average diameter of indigenous trees: 15.5cm
Table 6: Name of the plant species found in the sample plots under Acacia
auriculiformis and indigenous trees with their total number and average
height in replication 4.
Species name
Under Acacia
auriculiformis
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht.(c m) Total no
Avg
ht. cm)
Lygodium flexuosum Schiziaceae ** ** 1 40
Wikestoemia spp Wikestomiaceae 1 45 1 49
Achargash Microcos paniculata Tiliaceae 7 100 6 80
Arkila Ixora nigricans Rubiaceae ** ** 10/
12
20
Arshogonda Withania somnifera 3 70 1 120
Asamlata Eupatorium
odoratum
Compositae 5 120 1 130
Batna Quercus spicata 1 70 ** **
Ghuruchea Combritum spp Combretacea 12 60 ** **
Goda Vitis glabrata
1 40 ** **
Gondaraj Gardenia grandiflora Rubiaceae 7 60 ** **
Horina
/Horinna
Gota
Vitex peduncularis Verbenaceae ** ** 2 60
Jharugash Thysaenolena
maxima
Poaceae 3 50 4 80
103
Lantana Lantana camara Verbenaceae ** ** 1 120
Malastoma
/Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae ** ** 3 80
Meda 1 40 ** **
Narisa Polygonum spp Polygonaceae ** ** 2 39
Pitali ** ** 1 70
Pitraj Aphanamixis
polystachya
Meliaceae 1 75 1 79
Putijam Syzygium cumini Myrtaceae 2 80 5 90
Sample 5 1 bunch 115 1 120
Sample 6 2 20 2 30
Sample 7 ** ** 3 150
Shialkata Cnicus arvensis Compositae 2 11 ** **
Sullia kata Xanthium indicum Compositae 2 90 2 102
Tagar Tabernaemontana
divericata
Apocynaceae ** ** 1 100
Toynlata Jasminum spp Oliceea ** ** 2 120
Vitex Clerodendrum viscosum Verbenaceae 3 60 4 60
** Indicates that the species is absent to that plot.
Table 7: Tabulation of total number of plants (herbs, shrubs and tree
seedlings) found in all sample plots of Sylhet and Chittagong
under indigenous trees and Acacia auriculiformis with
their average height:
Species name
Under
Indigenous
trees
Under Acacia
auriculiformis
Local Name Scientific Name Family
Total no
Avg.
ht (c m) Total
no
Avg.
ht (cm)
Ageratum conyzoides Compositae 3 23 ** **
Borreria articularis
Rubiaceae 4 61 ** **
Commelina spp. Commelinaceae 5 51 ** **
104
Derris spp 2 36 ** **
Ichnocarpus frutescens
Apocynaceae 5 42 ** **
Lygodium flexuosum Schiziaceae 1 40 ** **
Piper boehmerifolium Piperaceae 1 35 ** **
Polygonum spp 14 50.5 ** **
Wikestoemia spp Wikestomiaceae 1 45 ** **
Achargash Microcos paniculata Tiliaceae 11 83.33 11 75
Algash 48 27 ** **
Alulata Dioscorea alata
Discoriaceae 2 300 2 100
Apang Nelsonia spp Acanthaceae 6 57 ** **
Arkila Ixora nigricans Rubiaceae 24 28.33 ** **
Arshogonda Withania somnifera 2 71 3 70
Asamgash Eupatorium odoratum Compositae 7 20 ** **
Asamlata Mikania cordata Compositae ** ** 3 120
Bash ghass Graminae 4 65.5 41 40
Batna Quercus spicata 6 115 1 70
Chotrapata Flaria interapta Articaceae 5 8 4 50
Dumur Ficus hispida Moraceae 1 62 ** **
Ghuruchea Combritum spp Combretacea 20 72.5 26 63.3
3
Goda ** ** 1 40
Golboroi/Jon
gliboroi
3 15 2 20
Gondaraj Gardenia grandiflora Rubiaceae ** ** 7 60
Hara 1 400 ** **
Horina
/Horinna
Gota
Vitex peduncularis Verbenaceae 5 75 ** **
Jharugash Thysaenolena maxima Poaceae 5 115 11 70
Jongliboroi 2 53 ** **
Kaispata Dalbergia stipularis Leguminosae 14 51.75 7 43.5
Khosh Byttneria pillosa Sterculiaceae 2 90 1 45
105
khoshia lata
Lantana Lantana camara Verbenaceae 8 115 ** **
Maittalata 1 80 ** **
Malastoma /Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae
7 80 2 100
Meda ** ** 1 40
Muschanilata Stephania
harnendifolia
Menispermaceae 1 75 ** **
Narisa Polygonum spp Polygonaceae 2 39 ** **
Pitali 1 70 ** **
Pitraj Aphanamixis polystachya Meliaceae 1 74 1 75
Putijam Syzygium cumini Myrtaceae 8 95 5 46.66
Sample 1 8 87.5 6 39.5
Sample 2 2 50 1 56
Sample 3 2 49 2 45
Sample 4 1 35 ** **
Sample 5 1 120 1 115
Sample 6 2 30 2 20
Sample 7 3 150 ** **
Sercuti Phyllanthus spp. Euphorbiaceae 1 120 ** **
Shialkata Cnicus arvensis Compositae 1 350 2 11
Sullia kata Xanthium indicum Compositae 2 102 2 90
Tagar Tabernaemontana
divericata
Apocynaceae 2 95 ** **
Toynlata Jasminum spp Oliceea 8 72 5 72
Uluson Saccharum spontaneum Cramineae 15 71 15 65
Umbrella 1 58 1 72
Vitex Clerodendrum viscosum Verbenaceae 13 51.75 10 44.25
Zongli
jumka/Jumkalata
Passiflora foetida Passifloraceae 2 116 1 120
106
Table 7 shows, in all plots of Sylhet and Chittagong, 52 species were found under
indigenous trees and 30 species were found under Acacia auriculiformis. 22 more species
was found under indigenous trees, which were absent under Acacia auriculiformis. In
most of the cases the average number of plants and their average height in sample plots of
indegenous trees are higher than that of plots under Acacia auriculiformis.
Major 10 species found under indegenous trees in maximum number and frequency is
Algash, Arkila (Ixora nigricans) Ghuruchea (Combritum spp) Ulusom (Saccharum
sportaneum) Kaispata (Dalbergia stipularis) Vitex (Clerodendrum viscosum) Achargash
(Microcos paniculata) Lantana (Lantana camara) Putijam (Syzygium cumini) and sample
1 respectively.
Major 10 species found under Acacia auriculiformis in maximum number and
frequency are Bashghass, Ghuruchea (Combritum spp), Uluson (Saccharum sportaneum),
Achargash (Microcos paniculata), Gharugash (Thysaenolena maxima), Vitex
(Clerodendrum viscosum), Gondaroj (Gardenia gardiflora), Kaispata (Dalbergia
stipularis), sample 1 and Putijam (Syzygium cumini) respectively.
Major10 species with maximum height found under indigenous tree species Hara,
Shialka (Cricus arvensis), Alulata (Dioscorea alata) sample 7, sample 5, Sercuti
(Phyllanthus spp), Jumkalata (Passiflora foetida), Gharugas (Thysaenolena maxima),
Batra (Quercus spicata) and Lantana (Lantana camara) respectively.
Major10 species with maximum height found under Acacia auriculiformis are
Asamlata (Mikania cordata), Jumkalata (Passiflora foetida), sample 5, Alulata (Dioscorea
alata), Melastoma (Melastoma malobathricum), Sulliakata (Xanthiun indicum), Achargash
(Microcos paniculata), Pitraj (Aphanamixis polystachya), Toynlata (Jasminum spp), and
Umbrella.
Comparison can be made in terms of the total number and average height of the
undergrowth species (Table 7) found under indigenous tree with that of Acacia
auriculiformis which are present in sample plots both under indigenous trees and Acacia
auriculiformis. For better understanding topmost 5 common undergrowth species are
compared in term of their maximum total number found under indigenous trees with that
of under Acacia auriculiformis. The 5 topmost species are Ghuruchea (Combritum spp),
Uluson (Saccharum sportaneum) Kaispata (Dalbergia stipularis) Vitex (Clerodendron
viscosum) and Achargash (Microcos paniculata).
107
The total number and average height of Ghuruchea (Combritum spp) under
indigenous tree are 20 and 72.5 cm respectively. While the figure under Acacia
auriculiformis are 26 and 63.33 respectively.
The total number and average height of Uluson (Saccharum sportaneum) under
indigenous tree are 15 and 71 cm. While the figure under Acacia auriculiformis are 15 and
65 cm respectively.
The total number and average height of Kaispata (Dalbergia stipularis) under
indigenous tree are 14 and 51.75 cm respectively. While the figure under Acacia
auriculiformis are 7 and 43.5 cm respectively.
The total number and average height of Vitex (Clerodendron viscosum) under
indigenous tree are 13 and 51.75 cm respectively. While the figure under Acacia
auriculiformis are 10 and 44.25 cm respectively.
The total number and average height of Achargash (Microcos paniculata) under
indigenous tree are 11 and 83.33 cm. While the figure under Acacia auriculiformis are 11
and 75 cm respectively.
Of these 5 species, when compared the figure of total number and average height
(Table 7) of species found under indigenous trees with that under Acacia auriculiformis,
for 3 species Achargash (Microcos paniculata), Ulusom (Saccharum sportaneum),
Kaispata (Dalbergia stipularis), the total number or average height found under
indigenous trees are higher than under Acacia auriculiformis. For other 2 species
Ghuruchea (Combritum spp), Vitex (Clerodendrum viscosum), the total number and
average height under indigenous trees are lower than that of Acacia auriculiformis.
Out of these 5 species of undergrowth 3 species i.e. 60% of the undergrowth
vegetation showed better performance under indigenous trees than that of Acacia
auriculiformis. Out of these 5 species of undergrowth 2 species i.e. 40% of the
undergrowth vegetation did not show better performance under indigenous trees than that
of Acacia auriculiformis.
When compared this way, the total number and average height of the common species
of plots under indigenous trees and Acacia auriculiformis (Table 7) it can be seen that for
most of the species, the total number found in all sample plots under indigenous trees and
their average height are higher than respective figures of undergrowth vegetation found
under Acacia auriculiformis plantation.
108
8.1.1.1 Is Acacia auriculiformis invasive in Bangladesh?
The result testifies that Acacia auriculiformis affects the indigenous plant
biodiversity under it by reducing the number and growth. There is less vegetation found
under Acacia auriculiformis plantation in comparison to the open areas or under
indigenous trees. In most of the cases, soil under Acacia was found totally or partially
exposed and presence of rills and splash soil erosion that enhance top soil removal or site
degradation, of course Acacia auriculiformis can grow on degraded land and in my field
visit, I had seen clear demonstration of this.
Whether Acacia auriculiformis should be called invasive in Bangladesh or not is a
controversial issue. All Acacia auriculiformis patches found in Bangladesh are plantations
raised by different Institutions, NGOs or by public. One of the characteristics of invasive
plants is that reproduces massively and displaces native vegetation by luxuriant growth
(CBD, 2001). Natural regeneration of Acacia auriculiformis is not too much apart in
Bangladesh. All the plantations are deliberately raised and once upon a time this species
was wellcomed in Bangladesh (Das, 1986). But being established now, this species is
impacting negatively to our indigenous biodiversity. This statement is clear from the
experiment result. There was observed a reducing growth and diversity of indigenous
vegetation under Acacia auriculiformis than under indigenous trees. My personal
perception regarding the stereotyped idea that invasive species should reproduce
massively should be redefined. This Papua New Guinean tree (Das, 1986) is also blamed
not to be favoured by indigenous birds for stay. Uddin and Mohammad (2003) determined
the impacts of invasive monocultures of Acacia auriculiformis and Eucalyptus
camaldulensis and soil properties and indigenous vegetation of Bangladesh. They found
slight variation on soil properties and considerable reduction of number and density of
indigenous undergrowth vegetation per hectare under invasive monoculture in comparison
to these in natural condition. Result of my study is co-axial with this. So Acacia
auriculiformis can be termed invasive tree in Bangladesh.
109
8.1.2. Sample plots in Eucalyptus camaldulensis and indigenous
trees plantations.
Replication 1: Location: Top of the hill near the Central Mosque of Chittagong University.
Slope: 5%
Altitude: 10m from the ground level.
Spacing: 2mX2m (both the plantation).
Age: 15 years for both and indigenous trees plantation.
Distance: between the following sample plots is 15m.
Average height of Eucalyptus camaldulensis is : 20m
Average diameter of Eucalyptus camaldulensis: 22cm
Average height of indigenous trees (Nim - Azadirachta indica) is : 15m
Average diameter of indigenous trees is: 17cm
Table 8: Name of the plant species found in the sample plots under Eucalyptus
camaldulensis and indigenous trees with their total number and average
height in replication 1.
Species name
Eucalyptus
camaldulensis
Under Indigenous
tree
Local
Name
Scientific Name Family
Total
no
Avg.
ht.(c m) Total
no
Avg
ht.(cm)
Blechnum orientali Div. Pteridophyta 1 60 ** **
Ficus semicordata Moraceae 2 30 8 40
Piper longum Piperaceae 1 40 ** **
Aalgash 25 12 30 55
Achargash Microcos paniculata Tiliaceae 4 50 ** **
Arkila Ixora nigricans Rubiaceae 3 25 11 25
Asamgash Eupatorium odoratum
Compositae 10 15 4 15
Asamlata Mikania cordata Compositae 2 30 ** **
110
Dudlata Hemidesmus indicus Periplocaceae 1 30 2 120
Jharugash Thysaenolena maxima Poaceae ** ** 4 60
Kaispata Dalbergia stipularis Leguminosae 6 20 8 45
Kali lata Thunbergia erecta ** ** 2 150
Khosh-
khoshia lata
Byttneria pillosa Sterculiaceae ** ** 1 80
Kurchi/kuch
vine drozop
Holarrhena
antidysenterica
Apocynaceae ** ** 3 45
Lajjabote Mimosa pudica
Mimusaceae ** ** 1 15
Lantana Lantana camara
3 50 2 50
Maittalata ** ** 1 80
Malastoma
/Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 1 40 18 55
Meda 2 30 3 40
Pitali Trewia polycarpa Euphorbiaceae ** ** 4 40
Putijam Syzygium cumini Myrtaceae 25 50 4 45
Sample 1 9 20 ** **
Sample 8 ** ** 30 10
Sercuti Phyllanthus spp. Euphorbiaceae 10 50 12 55
Shialkata Randia spicata
Rubiaceae 5 30 ** **
Son Imperata cylindrica
Graminae 9 70 15 30
Tagar Tabernaemontana
divericata
Apocynaceae ** ** 1 95
Toynlata Jasminum spp Oliceea 9 100 9 100
Zongli
jumka/Jumkalata Passiflora foetida Passifloraceae ** ** 1 120
** Indicates that the species is absent to that plot.
Replication 2:
111
Location: Mid slope of the hill near the entrance of the Institute of Forestry and
Environmental Sciences of Chittagong University.
Slope: 23%
Altitude: 10m from the ground level.
Spacing: 2mX2m (both the plantation).
Age: 15 years for both and indigenous trees plantation.
Distance: between the following sample plots is 13m.
Average height of Eucalyptus camaldulensis is : 18m
Average diameter of Eucalyptus camaldulensis: 17cm
Average height of indigenous trees (Chickrassy- Chickrassia tabularis) is: 14m
Average diameter of indigenous trees is: 15.5cm
Table 9: Name of the plant species found in the sample plots under Eucalyptus
camaldulensis and indigenous trees with their total number and average
height in replication 2.
Species name
Under
Eucalyptus
camaldulensis
Under Indigenous
tree
Local Name Scientific Name Family
Total
no
Avg.
ht
(c m)
Total
no
Avg
ht (cm)
Axonospora
cylenga
** ** 2 20
Lygodium
flexuosum
Schiziaceae ** ** 1 64
Mucuna spp Papilionaceae ** ** 1 61
Piper longum Piperaceae 1 45 ** **
Aal gassh 8 20 9 21
Arkila Ixora nigricans Rubiaceae 9 20 8 20
Asamlata Mikania cordata Compositae 4 18 9 70
Dhekilota Pteris biurata Pteridaceae 1 100 3 90
Dumur Ficus hispida Moraceae 1 20 3 19
Durba Cynodon dactylon
Graminae 1 55 15 60
112
Ghuruchea Combritum spp Combretacea 4 30 4 35
Lantana Lantana camara Verbenaceae 4 60 2 75
Maittalata 2 120 ** **
Malastoma /Indian
Rhododendron Melastoma
malabathricum
Melastomataceae 1 60 4 60
Muschanilata Stephania
harnendifolia
Menispermaceae ** ** 3 75
Pitraj Aphanamixis
polystachya
Meliaceae ** ** 1 115
Putijam Syzygium cumini Myrtaceae 2 72 3 72
Sercuti Phyllanthus spp. Euphorbiaceae 3 90 4 75
Shornalata Cuscuta reflexa Cuscutaceae ** ** 200 85
Son Imperata cylindrica
Graminae 2 60 3 60
Vitex Clerodendrum
viscosum
Verbenaceae 4 83 3 100
Zongli
jumka/Jumkalata
Passiflora foetida Passifloraceae 1 160 2 38
** Indicates that the species is absent to that plot.
Replication 3: Location: Near the botanical garden of Chittagong University.
Slope: Plain land.
Spacing: 2mX2m (both the plantation).
Age: 12 years for both and indigenous trees plantation.
Distance: between the following sample plots is 16m.
Average height of Eucalyptus camaldulensis is : 17m
Average diameter of Eucalyptus camaldulensis: 14.5cm
Average height of indigenous trees (Pitraj and Polash) is: 14m
Average diameter of indigenous trees is: 13.5cm
113
Table 10: Name of the plant species found in the sample plots under Eucalyptus
camaldulensis and indigenous trees with their total number and average
height in replication 3.
Species name
Eucalyptus
camaldulensis
Under Indigenous
tree
Local
Name
Scientific Name Family
Total
no
Avg.
ht
(c m)
Total
no
Avg
ht (cm)
Cyperus spp Cyperaceae 3 60 5 61
Hyptis suaveolens Lamiaceae 5 15 4 18
Merremia vitifolia Convolvulaceae ** ** 5 65
Premna esculenta Verbenaceae ** ** 4 50
Algash 6 20 6 23
Asamlata Mikania cordata Compositae 7 65 12 60
Lajjabote Mimosa pudica
Mimusaceae 2 12 4 10
Sample 9 2 25 ** **
Son Imperata cylindrica
Graminae 93 45 90 45
Vitex Clerodendrum viscosum Verbenaceae 3 70 4 70
** Indicates that the species is absent to that plot.
Replication 4: Location: Near the Malnichora tea estate of Sylhet.
Slope: 15%
Spacing: 2mX2m (both the plantation).
Age: 16 years for both and indigenous trees plantation.
Distance: between the following sample plots is 11m.
Average height of Eucalyptus camaldulensis is : 22m
Average diameter of Eucalyptus camaldulensis: 19cm
114
Average height of indigenous trees (Simul -Bombax ceiba and Radhachura- Caesalpinia
pulcherrima) is: 17m
Average diameter of indigenous trees is: 18.5cm
Table 11: Name of the plant species found in the sample plots under Eucalyptus
camaldulensis and indigenous trees with their total number and average
height in replication 4.
Species name
Under
Eucalyptus
camaldulensis
Under Indigenous
tree
Local Name Scientific Name Family
Total
no
Avg.
ht.(c m) Total
no
Avg
ht (cm)
Ageratum conyzoides Compositae ** ** 8 48
Crassocephalum
crepideoides
Compositae ** ** 6 58
Flemingia strobilifera 3 52 ** **
Thysanolaena
maxima
Graminae 12 63 ** **
Wikestoemia spp Wikestomiaceae ** ** 1 60
Achargash Microcos paniculata Tiliaceae 1 62 2 60
Arkila Ixora nigricans Rubiaceae 1 50 2 42
Asamgash Eupatorium odoratum Compositae 8 115 10 140
Asamlata Mikania cordata Compositae 2 200 6 165
Chotrapata/
Bichuti Tragia involucrata
Euphorbiaceae ** ** 3 63
Dudlata Hemidesmus indicus
Periplocaceae 1 45 1 60
Ghuruchea Combritum spp Combretacea 15 58 20 50
Huijjagash ** ** 1 80
Muschanilata Stephania harnendifolia Menispermaceae 3 65 3 95
Sample 10
19 86
Shornalata Cuscuta reflexa Cuscutaceae 190 73 200 75
Soilata Pueraria spp Papilionaceae 2 85 2 90
115
Son Imperata cylindrica
Graminae 140 130 200 130
Vitex Clerodendrum viscosum Verbenaceae 10 62 12 60
** Indicates that the species is absent to that plot.
Table 12: Tabulation of total number of plants (herbs, shrubs and tree
seedlings) found in all sample plots of Sylhet and Chittagong
under indigenous trees and Eucalyptus camaldulensis.
Species name
Under
Eucalyptus
camaldulensis
Under
Indigenous trees
Local
Name
Scientific Name Family
Total
no
Avg.
ht.(cm) Total
no
Avg.
ht.(cm)
Ageratum conyzoides Compositae ** ** 8 48
Axonospora cylenga ** ** 2 20
Blechnum orientali Div.Pteridophyta 1 60 ** **
Crassocephalum
crepideoides
Compositae ** ** 6 58
Cyperus spp Cyperaceae 3 60 5 61
Ficus semicordata Moraceae 2 30 7 40
Flemingia strobilifera 3 52 ** **
Hyptis suaveolens Lamiaceae 5 15 4 18
Lygodium flexuosum Schiziaceae ** ** 1 64
Lygodium flexuosum Schiziaceae ** ** 1 64
Merremia vitifolia Convolvulaceae ** ** 5 65
Mucuna spp Papilionaceae ** ** 1 61
Piper longum Piperaceae 2 43 ** **
Premna esculenta Verbenaceae ** ** 4 50
Thysanolaena maxima Graminae 12 63 ** **
Wikestoemia spp Wikestomiaceae ** ** 1 60
Aalgash 39 17. 33 45 33
Achargash Microcos paniculata Tiliaceae 5 56 2 60
Arkila Ixora nigricans Rubiaceae 13 31. 67 21 29
116
Asamgash Eupatorium odoratum
Compositae 18 65 14 77.5
Asamlata Mikania cordata Compositae 20 78. 75 27 98. 33
Chotrapata/
Bichuti Flaria interapta Articaceae ** ** 3 63
Dhekilota Pteris biurata Pteridaceae 1 100 3 90
Dudlata Hemidesmus indicus Periplocaceae 2 37.5 3 90
Dumur Ficus hispida Moraceae 1 20 3 19
Durba Cynodon dactylon
Graminae 1 55 15 60
Ghuruchea Combritum spp Combretacea 19 44 24 42. 50
Jharugash Thysaenolena maxima Poaceae ** ** 4 60
Kaispata Dalbergia stipularis Leguminosae 6 20 8 45
Kurchi/kuch
vine drozop
Holarrhena
antidysenterica
Apocynaceae ** ** 3 45
Lajjabote Mimosa pudica
2 12 5 12.5
Lantana Lantana camara Verbenaceae 7 52 4 62.5
Maittalata 2 120 1 80
Malastoma /Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 2 50 22 57.5
Meda 2 30 3 40
Muschanilata Stephania harnendifolia Menispermaceae 3 65 6 85
Pitraj Aphanamixis
polystachya
Meliaceae ** ** 1 115
Putijam Syzygium cumini Myrtaceae 27 61 7 58.5
Sample 1 9 20 ** **
Sample 10 ** ** 19 86
Sample 8 30 10 ** **
Sample 9 2 25 ** **
Sercuti Phyllanthus spp. Euphorbiaceae 13 70 16 65
Shialkata Randia spicata
Rubiaceae 7 57.
50
** **
117
Shornalata Cuscuta reflexa Cuscutaceae 190 73 400 80
Soilata Pueraria spp Papilionaceae ** ** 2 90
Son Imperata cylindrica
Graminae 244 76.
25
305 78. 33
Tagar Tabernaemontana
divericata
Apocynaceae
Toynlata Jasminum spp Oliceea 9 100 2 40
Vitex Clerodendrum viscosum Verbenaceae 17 71. 67 19 76. 67
Zongli
jumka/Jumkalata Passiflora foetida Passifloraceae 1 100 1 120
** Indicates that the species is absent to that plot.
Table 12 shows, in all plots of Sylhet and Chittagong, 42 species of plants was
found under indigenous trees while 35 species of plants was found under Eucalyptus
camaldulensis. 7 more species was found under sample plot of indigenous trees than that
of Eucalyptus. In most of the cases, the average number of plants and their average height
found in sample plots under indigenous trees are higher than that of the plots under
Eucalyptus camaldulensis.
Major 10 species found in sample plots under Eucalyptus camaldulensis in
maximum in terms of their total number are Son (Imperate cylindrica), Shornalata
(Cuscuta reflexa), Aalgash, Sample 8, Putijam (Syzygium cumini), Asamlata (Mikania
cordata), Ghuruchea (Combritum spp), Asamgash (Eupatorium odoratum), Vitex
(Clerodendrum viscosum) and Arkilea (Ixora nigricans).
Major10 species found in sample plots under indigenous trees in maximum in terms
of total numbers are Shornalata (Cuscuta reflexa), Son (Imperate cylindrical), Aalgash,
Asamlata (Mikania cordata), Ghuruchea (Combritum spp), Melastome (Melastome
malabathricum), Arkile (Ixora nigricans), Sample 10, Vitex (Clerodendrum viscosum)
and Sercuti (Phyllanthus spp).
Major 10 species found under Eucalyptus camaldulensis in terms of their maximum
height are Asamlata (Mikania cordata), Vitex (Clerodendrum viscosum), Miattalata,
Shialkata (Randia spicata), Son (Imperate cylindrica), Dhekilota (Pteris biurata),
Toynlata (Jasminum spp), Jumkalata (Passiflora foetida), Arkile (Ixora nigricans) and
Shornalata (Cuscuta reflexa).
118
Major 10 species found under indigenous trees interms of their maximum height are
Jumkalata (Passiflora foetida), Putijam (Syzygium cumini), Asamlata (Mikania cordata),
Soilata (Pueraria spp), Sample 10, Muschanilata (Stephania harnendifolia), Maittalata,
Duslata (Hemidesmus indicus), Asamgash (Eupatorium odoratum), and Vitex
(Clerodendrum visecosum).
Comparison can be made in terms of the undergrowth species total number and
average height found under indigenous tree with that of Eucalyptus camaldulensis which
are present in sample plots under both indigenous trees and Eucalyptus camaldulensis.
The topmost 5 species are Shornalata (Cuscuta reflexa), Son (Imperate cylindrica),
Aalgash, Asamlata (Mikania cordata), and Ghuruchea (Combritum spp) (Table 12).
The total number and average height of Shornalata (Cuscuta reflexa) under
indigenous trees are 400 and 80 cm respectively while the figures under Eucalyptus
camaldulensis are 73 and 190 cm respectively.
The total number and average height of Son (Imperate cylindrica)under indigenous
trees are 305 and 78.33 cm respectively while the figures under Eucalyptus camaldulensis
are 244 and 76.25 cm respectively.
The total number and average height of Aalgash under indigenous trees are 45 and
33 cm respectively while the figures under Eucalyptus camaldulensis are 39 and 17.33 cm
respectively.
The total number and average height of Asamlata (Mikania cordata) under
indigenous trees are 27 and 98.33 cm respectively while the figures under Eucalyptus
camaldulensis are 20 and 178.75 cm respectively.
The total number and average height of Ghuruchea (Combritum spp) under
indigenous trees are 24 and 42.50 cm respectively while the figures under Eucalyptus
camaldulensis are 19 and 44 cm respectively.
Of these 5 species when compared the their respective figures of total number and
average height found under indigenous trees with that under Eucalyptus camaldulensis, 4
species, Shornalata (Cuscuta reflexa), Son (Imperate cylindrica), Aalgash, and Asamlata
(Mikania cordata) showed better performance under indigenous trees. Their total number
and average height under indigenous trees are higher than that of Eucalyptus
camaldulensis. 1 species, Ghuruchea (Combritum spp) was found less in number but
higher in average height under indigenous trees than Eucalyptus camaldulensis.
119
4 ground vegetation species out of 5, i.e. 80% of the undergrowth vegetation showed
better performance in plantations of indigenous trees than Eucalyptus camaldulensis
When compared this way, it is observed, for most of the common species (found in
plots of both under indigenous trees and Eucalyptus camaldulensis) their total number and
average height (Table 12) are higher under indigenous trees than that under Eucalyptus
camaldulensis.
Fig: Eucalyptus camaldulensis.
120
8.1.2.1. Is Eucalyptus camaldulensis invasive in Bangladesh?
The result testifies that Eucalyptus camaldulensis affects the indigenous plant
biodiversity under it by reducing the number and growth. There is less vegetation found
under Eucalyptus camaldulensis plantation in comparison to the open areas or under
indigenous trees. In most of cases, soil under Eucalyptus camaldulensis was found totally
or partially exposed and presence of rills and splash soil erosion that enhance top soil
removal or site degradation, of courseEucalyptus camaldulensis can grow on degraded
land and during the field visit, this was proved.
Whether Eucalyptus camaldulensis should be called invasive in Bangladesh or not is
also a controversial issue! Eucalyptus plantation consists of a substantial land area in
Bangladesh (FAO, 1995) although the species is now banned in Bangladesh. The species
was found throughout the country. It is popular in social forestry, agroforestry, home
garden, marginal land plantations and cropland agroforestry programmes. In roadside and
outer periphery of home gardens the species is found commonly in Bangladesh. But this
species is strongly blamed for negative impact on agrs-ecosystem.
Dabral et al. (1987) found less undergrowth vegetation under Eucalyptus plantation
in comparison to that of native condition. Lisa and Michelsen (1993) reported lesser extent
of vegetation under Eucalyptus monoculture than original native trees. Ranasinghe and
Jaysuriya (1991) reported reduced plant diversity and slightly acidic condition under
Eucalyptus than other indigenous trees. Uddin and Mohammad (2003) determined the
impact of Eucalyptus spp on indigenous vegetation and found per hectare considerably
reduced density of undergrowth plant species in comparison to natural forest in
Bangladesh. The present findings are concomitant to those findings. So Eucalyptus
camaldulensis may be termed as an invasive species in Bangladesh!
121
8.1.3. Sample plots in Melaleuca leucodendron and indigenous
trees plantations.
Replication 1:
Location: At the bank of the lake of the Institute of forestry and Environmental Sciences,
Chittagong University.
Site condition:Lower hill slope on the bank of the lake.
Slope: 30%
Spacing: 2mX2m (both the plantation).
Age: 11 years for both Melaleuca leucodendron and indigenous trees plantation.
Distance: between the following sample plots is 7m.
Average height of Melaleuca leucodendron is: 13m
Average diameter of Melaleuca leucodendron: 15cm
Average height of indigenous trees (Kadam -Anthocephallus chinensis and other species)
is : 0m
Average diameter of indigenous trees is: 12.5cm
Table 13:Name of the plant species found in the sample plots under Melaleuca
leucodendron and indigenous trees with their total number and average
height in replication 1.
Species name Under
Melaleuca
leucodendron
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht.(c m) Total
no
Avg.
ht (cm)
Achargash Microcos paniculata Tiliaceae 4 95 3 100
Apang Nelsonia spp Acanthaceae ** ** 1 40
Arshogonda Withania somnifera 1 90 ** **
Asamlata Mikania cordata Compositae 4 120 10 90
Ghuruchea Combritum spp Combretacea 3 85 3 90
122
Ghuruchea Combritum spp Combretacea 2 60 5 45
Jharugash Thysaenolena maxima Poaceae 5 90 4 93
Koloi lata Coccinea cordifolia Cucurbitaceae 1 98 ** **
Lantana Lantana camara Verbenaceae 1 65 2 62
Maittalata ** ** 1 125
Putijam Syzygium cumini Myrtaceae 3 88 2 92
Sercuti Phyllanthus spp. Euphorbiaceae 1 80 2 86
Shialkata Randia spicata
Rubiaceae 3 115 5 95
Tagar Tabernaemontana
divericata
Apocynaceae ** ** 1 95
Vitex Clerodendrum viscosum Verbenaceae 3 55 3 75
** Indicates that the species is absent to that plot.
Replication 2:
Location: At the back of the Academic Building of the Institute of forestry and
Environmental Sciences, Chittagong University.
Slope: 0 % (Plain land)
Spacing: 2mX2m (both the plantation).
Age: 13 years for both Melaleuca leucodendron and indigenous trees plantation.
Distance: between the following sample plots is 100m.
Average height of Melaleuca leucodendron is: 11m
Average diameter of Melaleuca leucodendron: 14cm
Average height of indigenous trees (Mahagoni, Telsur, Gargan) is: 12m
Average diameter of indigenous trees is: 10.5cm
Table 14: Name of the plant species found in the sample plots under Melaleuca
leucodendron and indigenous trees with their total number and average
height in replication 2.
123
Species name
Under
Melaleuca
leucodendron
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht.(c m) Total
no
Avg.
ht (cm)
Ageratum conyzoides Compositae 3 30 3 53
Caperis spp Caperidaceae ** ** 4 30
Asamgash Eupatorium odoratum Compositae 4 90 5 85
Asamlata Mikania cordata Compositae 12 63 10 60
Bangla kachu Colocasia esculanta Araceae 7 30 2 50
Dhekilota Pteris biurata Pteridaceae 60 44 72 40
Dumur Ficus hispida Moraceae 1 120 ** **
Lajjabote Mimosa pudica
Mimusaceae 2 20 3 23
Malastoma /Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 1 65 2 75
Meda ** ** 1 100
Pipul Piper sylvaticum Piperaceae ** ** 1 55
Putijam Syzygium cumini Myrtaceae 1 12 2 10
Sample 11 14 35 ** **
Sample 12 1 120
Sheora Streblus asper Moraceae 1 25 1 27
Son Imperata cylindrica
Graminae 15 60 30 58
** Indicates that the species is absent to that plot.
Replication:3
Location: Near the Pritilata Hall of Chittagong University.
Slope: 0 % (Plain land)
Spacing: 2mX2m (both the plantation).
Age: 15 years for both Melaleuca leucodendron and indigenous trees plantation.
124
Distance: between the following sample plots is 15m.
Average height of Melaleuca leucodendron is: 13m
Average diameter of Melaleuca leucodendron: 14cm
Average height of indigenous trees ( Mix plantation of Krishnochura -Delonix regiaand,
Gutgutia -Bursera serrata and Polash) is : 16m
Average diameter of indigenous trees is: 14.5cm
Table 15: Name of the plant species found in the sample plots under Melaleuca
leucodendron and indigenous trees with their total number and average
height in replication 3.
Species name Under
Melaleuca
leucodendron
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht.(c m) Total
no
Avg.
ht (cm)
Adiantum lessata ** ** 1 30
Trichosanthes spp Cucurbitaceae 1 60 ** **
Achargash Microcos paniculata Tiliaceae 2 55 5 60
Bet/ Betgota Calamus viminalis Palmeae 4 300 5 280
Dumur Ficus hispida Moraceae 2 25 2 30
Ghuruchea Combritum spp Combretacea 5 85 5 90
Gondo
badali
Paederia foetida 1 100 ** **
Horina
/Horinna Gota
Vitex peduncularis Verbenaceae 14 70 12 88
Kaowatoni Glycosmis spp. Rutaceae 1 70 ** **
Lantana Lantana camara Verbenaceae 1 65 2 50
Melastoma
/Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 2 70 3 75
125
Son Imperata cylindrica
Graminae 8 70 15 72
** Indicates that the species is absent to that plot.
Replication: 4
Location: Khadim nagar, Sylhet.
Slope: 15 % (Plain land)
Spacing: Irrigular (both the plantation).
Age: 11 years for both Melaleuca leucodendron and indigenous trees plantation.
Distance: between the following sample plots is 18m.
Average height of Melaleuca leucodendron is: 11m
Average diameter of Melaleuca leucodendron: 14.5cm
Average height of indigenous trees (Jam -Syzygium cumini and Kanthal- Artocarpus
heterophyllus) is : 10m
Average diameter of indigenous trees is: 22.5cm
Table 16: Name of the plant species found in the sample plots under Melaleuca
leucodendron and indigenous trees with their total number and average
height in replication 4.
Species name Under
Melaleuca
leucodendron
Under
Indigenous tree
Local Name Scientific Name Family
Total
no
Avg.
ht (c m) Total
no
Avg
ht (cm)
Boewia spp.
** ** 1 25
Dryopteris spp
1 60 ** **
Glycosmis spp Rutaceae 2 55 2 64
Gymnema
acuminatae
Asclepediaceae ** ** 3 45
Leucas aspera Labiatae ** ** 1 35
Lygodium flexuosum Schiziaceae 1 55 ** **
126
Bishkatali Polygonum hydropiper 3 65 2 70
Mal lota Derris scandens 1 90 1 100
Sample 13 12 60 10 63
Sample 14 ** ** 60 15
Shialkata Randia spicata
Rubiaceae 1 120 1 130
** Indicates that the species is absent to that plot.
Table 17: Tabulation of total number of plants (herbs, shrubs and tree
seedlings) found in all sample plots of Sylhet and Chittagong
under indigenous trees and Melaleuca leucodendron
Species name
Under Melaleuca
leucodendron
Under
Indigenous trees
Local
Name
Scientific Name Family
Total
no
Avg.
ht.(cm) Total
no
Avg
ht (cm)
Dhekilota Pteris biurata Pteridaceae 60 44 72 50
Ageratum conyzoides Compositae 3 30 3 53
Caperis spp Caperidaceae ** ** 4 30
Adiantum lessata ** ** 1 30
Trichosanthes spp Cucurbitaceae 1 60 ** **
Boewia spp
** ** 1 25
Dryopteris spp
1 60 ** **
Glycosmis spp Rutaceae 2 55 2 64
Gymnema
acuminatae
Asclepediaceae ** ** 3 45
Leucas aspera Labiatae ** ** 1 35
Lygodium flexuosum Schiziaceae 1 55 ** **
Panicum spp Graminae ** ** 60 15
127
Asamlata Mikania cordata Compositae 16 91 20 75
Son Imperata cylindrica
Graminae 8 70 15 72
Ghuruchea Combritum spp Combretacea 10 115 8 75
Horina
/Horinna Gota
Vitex peduncularis Verbenaceae 14 70 12 56
S-13 12 60 10 63
Achargash Microcos paniculata Tiliaceae 6 75 8 80
Shialkata Randia spicata
Rubiaceae 4 117.5 6 112.5
Asamgash Eupatorium
odoratum
Compositae 4 90 5 85
Bet/ Betgota Calamus viminalis Palmeae 4 300 5 280
Malastoma /Indian
Rhododendron
Melastoma
malabathricum
Melastomataceae 3 67.5 5 75
Jharugash Thysaenolena maxima Poaceae 5 90 4 93
Putijam Syzygium cumini Myrtaceae 4 50 4 51
Lajjabote Mimosa pudica
Mimusaceae 2 20 3 23
Vitex Clerodendrum viscosum Verbenaceae 3 55 3 75
Bangla kachu Colocasia esculanta Araceae 7 30 2 50
Bishkatali Polygonum lanatum Polygonaceae 3 65 2 70
Lantana Lantana camara Verbenaceae 1 65 2 62
Sercuti Phyllanthus spp. Euphorbiaceae 1 80 2 86
Apang Nelsonia spp Acanthaceae ** ** 1 40
Maittalata ** ** 1 125
Mal lota Derris scandens 1 90 1 100
Meda ** ** 1 100
Pipul Piper sylvaticum Piperaceae ** ** 1 55
Sample 12 ** ** 1 120
Tagar Tabernaemontana
divericata
Apocynaceae ** ** 1 95
Arshogonda Withania somnifera 1 90 ** **
128
Dumur Ficus hispida Moraceae 3 72.5 ** **
Gondobadali Paederia foetida Rubiaceae 1 100 ** *
Kaowatoni Glycosmis spp. Rutaceae 1 70 ** **
Koloi lata Coccinea cordifolia Cucurbitaceae 1 98 ** **
Sample 11 14 35 ** **
Table 17 shows that, 31 plant species was found in all sample plants of under
Melaleuca leucodendron tree and 34 plant species was found under indigenous trees. Only
3 undergrowth plant species was found more under indigenous trees than Melaleuca
leucodendron.
Major 10 species found under Melaleuca in terms of their total number are Dhekilata
(Pteris biurata), Asamlata (Mikania cordata), Sample 11, Horina (Vitex peduncularis),
Sample 13, Ghuruchea (Combritum spp), Son (Imperate cylindrical), Bangla Kachu
(Colocasia esculanta), Achargash (Microcos paniculata) and Jharugash (Thysaenolena
maxima).
Major10 species found under indigenous tree in terms of their total number are
Dhekilata (Pteris biurata), Panicum spp, Asamlata (Mikania cordata), Son (Imperate
cylindrical), Ghuruchea (Combritum spp), Horina (Vitex peduncularis), Sample 13,
Achargash (Microcos paniculata), Shialkata (Randia spicata) and Asamlata (Mikania
cordata). 5 major species (in terms of their total number under indigenous trees) that were
present in common in sample plots both under indigenous and Melaleuca leucodendron
trees and their total number and average height found in plantations of indigunous and
Melaleuca leucodendron trees can be considered for rapid comparison of invasiveness of
Melaleuca leucodendron.
5 species are Dhekilata (Pteris biurata), Asamlata (Mikania cordata), Son (Imperate
cylindrica), Ghuruchea (Combritum spp), and Horina (Vitex peduncularis).
Total number and average height of Dhekilata (Pteris biurata) under Melaleuca
leucodendron are 60 and 44 cm respectively while the figures under indigenous trees are
72 and 50 cm respectively.
Total number and average height of Asamlata (Mikania cordata) under Melaleuca
leucodendron are 16 and 91 cm respectively while the figures under indigenous trees are
20 and 75 cm respectively.
129
Total number and average height of Son (Imperate cylindrica) under Melaleuca
leucodendron are 8 and 70 cm respectively while the figures under indigenous trees are 15
and 72 cm respectively.
Total number and average height of Ghuruchea (Combritum spp) under Melaleuca
leucodendron are 10 and 115 cm respectively while the figures under indigenous trees are
8 and 75 cm respectively.
Total number and average height of Horina (Vitex peduncularis) under Melaleuca
leucodendron are 14 and 70 cm respectively while the figures under indigenous trees are
12 and 56 cm respectively.
Out of 5 species, 2 species Dhekilata (Pteris biurata) and Asamlata (Mikania
cordata) were found having average height and total number greater than under
indigenous trees respective figures under Melaleuca leucodendron. Other 2 species
Ghuruchea (Combritum spp) and Horina (Vitex peduncularis) were found having total
number and average height under Melaleuca leucodendron than that under indigenous
trees. 1 species Asamlata (Mikania cordata) out of these 5 undergrowth vegetation was
found having greater in number but average height was less under indigenous trees
plantation in comparison to Melaleuca leucodendron plantation. On the other hand
average height of Asamlata (Mikania cordata) was higher but total number was less under
Melaleuca leucodendron plantation than under indigenous trees plantation.
So inference can be drawn that of all the undergrowth vegetation found in the plots
under plantation of indigenous trees and Melaleuca leucodendron, 50% of the
undergrowth species was found showing well growth under Melaleuca leucodendron and
50% of the vegetation grows well under indigenous trees.
8.1.3.1. Is Melaleuca leucodendron invasive in Bangladesh?
The result shows apparently that Melaleuca does not have significant impact on
undergrowth vegetation in comparison to native trees. But Melaleuca is blamed in many
countries to impose negative impact on biodiversity of native flora and fauna (Serbesoff
King, 2003). Pernas and Francois (2003) ascertained that Melaleuca rapidly invades
130
disturbed and undisturbed habitats and forms dense impenetrable forest and ultimately
displace native plants. But present findings confront with those findings.
Actually, there is no established plantation of Melaleuca in our country and no
Melaleuca large area monoculture is raised. As an ornamental plant, many institutions
have planted dispersely Melaleuca on limited scale for beautification of the Premise.
Probably, that’s why Melaleuca could not produce effect on the ecosystem yet. But these
species is strongly objected for producing health hazard (Pollen allergy) because the
flowers and new folige produce airborn substance that causes severe asthma- like
symptom in Sensitive people.
Fig : Melaleuca
131
8.1.4. Comparison of invisibility of Acicia auriculiformis,
Eucalyptus camaldulensis and Melaleuca leucadendron:
From field visit, it was seen less extent of vegetation under both Acacia
auriculiformis and Eucalyptus camaldulensis. My experiment findings also testify this.
But under Melaleuca no sensible difference was observed in comparison the open nearby
open area or nearby indigenous tree undergrowth.
In all sample plots of Sylhet and Chittagong all together 52 undergrowth plant
species was found under indigenous trees and 30 undergrowth plant species was found
under Acacia auriculiformis. 22 more undergrowth plant species were found under
indigenous trees, which were absent under Acacia auriculiformis. In most of the cases the
average number of plants and their average height in sample plots of indegenous trees are
higher than that of plots under Acacia auriculiformis.
In all sample plots of Sylhet and Chittagong, all together 42 species of undergrowth
plants was found under indigenous trees while 35 species of undergrowth plants was found
under Eucalyptus camaldulensis. 7 more species was found under sample plot of
indigenous trees than that of Eucalyptus. The average number of plants and their average
height In most of the cases, found in sample plots under indigenous trees are higher than
that of the plots under Eucalyptus camaldulensis.
Al together 31 undergrowth plant species was found in all sample plots under
Melaleuca tree and 34 undergrowth plant species was found under indigenous trees. Only
3 undergrowth plant species was found more under indigenous trees than Melaleuca
leucadendron.
132
Result shows 40% of the undergrowth vegetation was seen growing better under
Acacia auriculiformis, 20% of the undergrowth vegetation under Eucalyptus
camaldulensis and 50% of the undergrowth vegetation under Melaleuca leucodendron
plantation. If invasiblity of these three species is ranked, Eucalyptus camaldulensis ranks
first followed by Acicia auriculiformis and Melaleuca leucadendron.
8.1.5. Mikania cordata, Eupatorium odoratum, Ipomea carnea
and Lantana camara –invasive species in different ecosystems of
Bangladesh:
8.1.5.1 Asamlata (Mikania cordata).
Family: Asteraceae
Vegetative character: Mikania cordata is perennial fast growing weed. Mikania
cordata is a vine.The leaves of Mikania are cordate shaped. Mikania cordata shows
vigorous branching behaviour. On average 25-30 branches were found on sites of medium
infestation in 2m by 2m random sample plots. Most of the branches develop sub-branch
from their nodes except some base nodes. From nearly 50% of the nodes of horizontal soil
touching branches develop sub-branches. From each aerial branches node, 2 leaves and
one branch develop. The branch comes out from the middle of the leaf base. Sub-branches
again develop sub-branches from their nodes. This level continues and ultimately a
Mikania bush is formed and suppress the indigenous plant to grow. The nodel length of
the branches averages 10-12 cm. It was found that a thicket of 2.5 m tall Mikania had
developed 30 branches. The branches of some node are long (80-100 cm) and that of
others are small (10 cm). The upper side of the aerial horizontal branches is blackish blue
while the lower root is green. Stem with white hair while the leaves are smooth.
Sometimes branches (vines) coalesces together themselves spirally to form a bunch of the
tops and all the tops joint by then spiral up when they get any support. If the support is a
free or seedling they even reach to the top and suppresses the plant.
133
Habitat: Generally Mikania cordata prefers sunny, moist and fertile places, such
as road sides and the sides of stream. However it was also found it in arid soil and shady
places. It cannot tolerate dense shade. Observation suggests that it can grow in fertile or
unfertile soil. The various habitat attributes to extensive invasibility. It is currently
distributed in the whole country as a massive problem weed. The probable causes for the
high infestation of Mikania in Bangladesh is the high disturbance to the ecosystems and
the absence of host-specific natural enemies.
Growth: Growth of Mikania cordata is 2.2 m per month.
Biomass: In randomly taken sample plots of 2m by 2m, the weight of Mikania
cordata was found to be 2.50 kg to 4.20 kg on sites of medium infestation to heavy
infestation respectively. When converted to hectare, the biomass is 6250kg/ha to
10500kg/ha on sites of medium infestation to heavy infestation respectively.
Mode of reproduction: Multiplication of the weed is through wind-dispersed seeds
and vegetative means. Mikania reproduces vigorously by seeds. Mikania also reproduces
by vegetative means.
Ecological threat: Survey showed that it poses a serious threat to natural forests,
plantations and agricultural systems in Bangladesh. The weed can smother and pull over
plants, and the damage caused is extensive. Mikania cordata is a destructive weed of the
natural and man made forests in Bangladesh. Mikania quickly climbs over trees and
shrubs and even kill them by strangling and shading. Some of the Mikania vines coalesces
together at the top of the branches and ascends up when they get any support. Tree
seedlings are used as support by the Mikania and reaches even at the top of the seedlings
or saplings and sometimes cover them completely and suppress them to grow. Most of the
cases, they are difficult to remove completely because of massive growth. Sometimes the
weed completely covers the indigenous vegetations that grows with it and suppresses other
native plants to grow in that area. The weed competes with other indigenous plants for
nutrients and moisture.
Economic threat: Cost-escalation and income reduction are the main economic
impacts due to Mikania infestation in cultivated lands. Forests need frequent weeding to
get rid of the weed.
134
Table 18: Showing some of the allied species growing with Mikania cordata
Local Name
Scientific Name Family
Adiantum lessata
Ageratum conyzoides Compositae
Crassocephalum
crepideoides
Compositae
Crotalaria pallida Papilionaceae
Cyperus spp Cyperaceae
Dalbergia stipularis Leguminosae
Dryopteris spp
Hyptis suaveolens Lamiaceae
Leucas aspera Labiatae
Ludwigia repens Onagraceae
Merremia vitifolia Convolvulaceae
Mucuna spp Papilionaceae
Nelsonia spp Acanthaceae
Passiflora foetida Passifloraceae
Premna esculenta Verbenaceae
Thysanolaena maxima Graminae
Algash
Alulata Dioscorea alata
Discoriaceae
Asamgash Eupatorium odoratum Compositae
Bash ghass Graminae
Bet/ Betgota Calamus viminalis Palmeae
Bon-alulata Diascorea spp Diascoreaceae
Chailata/Shimlata Pueraria spp
Papilianaceae
Dudlata Hemidesmus indicus
Periplocaceae
Gondobadali Paederia foetida Rubiaceae
135
Kali kochi shak Vigna spp. Leguminosae
Khosh khoshia lata Byttneria pillosa Sterculiaceae
Koloi lata Coccinea cordifolia Cucurbitaceae
Lantana Lantana camara Verbenaceae
Muschanilata Stephania harnendifolia Menispermaceae
Sample 15
Son Imperata cylindraca Verbenaceae
Sample 16
Sample 17
Fig : Mikania
136
i
8.1.5.2 Asam gash (Eupatorium odoratum)
Family: Asteraceae
Introduction: Eupatorium odoratum is a dominant, competitive and wide
spread invasive species in Bangladesh. In Bangladesh it is a common invasive weed of
fallows and bush fallow sites, wastelands and forests.
Vegetation characters: The species is soft when young and hard when old. Leaves
are triangular, hairy and rough with three prominent veins. Eupatorium is a perennial
shrub, which attains a height of 3m. But, in maximum cases the height remains within
2.5m. Eupatorium sometimes adopt a climbing habit and is seen to reach a height of 5.5m.
Eupatorium grows in bunch. From the base of each older stem several (4-5)
branches come out. From the nodes of each individual stem, branches again come out.
This process continues and ultimately a bush of Eupatorium is formed. A Eupatorium
stem of 1.5 m height gives rise to nearly 5 / 6 branch stems on an average. The average
nodal length of an older stem may be 15-18 cm.
No of stem per unit area: In 2m by 2m sample plot taken randomly, it was found
on an average, 70 stems in sites heavily infested by Eupatorium and 50 stems in sites of
medium infestation.
Biomass: In 2m by 2m sample plot, taken randomly from the thicket of
Eupatorium odoratum, the biomass ranges from 4.10 kg to 6.30 kg (of height range 0.80 to
1.6 m respectively) depending on the intensity of invasion to the habitat. When converted
137
to hectare, the biomass is10250 kg per ha to 15750 kg per ha on sites of medium
infestation to heavy infestation respectively.
Growth: Growth of Eupatorium odoratum is 45cm per month in growing season
(March-July).
Mode of reproduction: It can reproduce both by seeds and vegetative means.
Eupatorium is a prolific seed producer. The seeds were seen to disperse to a wider range,
which is a good character of an invasive plant. During the dry season, the weeds including
the root system dry up, but after the rains they resprout rapidly within few days. Even
burnt weeds may re-grow fast through the stem base.
Habitat: Eupatorium grows well in open areas. Of course, Eupatorium has thin
affinity to habitat near the wetland, canal side, pond embankment etc, in comparison to
other invasives like Mikania cordata, Lantana camara, Melaleuca leucodendron etc.
Ecological threat: The species was seen to causes large-scale habitat destruction
by suppressing the other vegetation and can be identified as a threat to biodiversity. The
plant is extremely well distributed by seed and grows into dense impenetrable bushes out
competing all indigenous vegetation and animal access to food and water sources.
Eupatorium has the ability to establish itself very rapidly and to suppress persistent plants
or nearby plants by its massive growth. Its rapid multiplication and the resprouting ability
of established plants make it very difficult to control infestations.
With the increase of age of the bush of Eupatorium, the leaves in the lower part of
the plant dies out giving a skeletal appearance to the lower part but the upper portion of
the bush or plant remain vigorous and lush green. Below the older part of the bush, no
undergrowth can be seen and the soil is totally exposed. Rotten leaves and stems of the
plant is seen there. The bush looks green at the first appearance, but anybody opens the
bush by cutting down some stems from one side, one can see the beggar description
condition of the lower bush part. The bush also dense enough to obstruct the movement of
animals (vertebrate/ invertebrate) through it. There is almost no undergrowth vegetation is
seen in the core part of the bush. Lesser amount of vegetation was seen to grow below the
outer circumference of the bush. It is a common weed in waste lands and agricultural lands
in Bangladesh.
Table 19: Some of the allied species growing with Eupatorium odoratum.
138
Local Name
Scientific Name Family
Ageratum conyzoides Compositae
Borreria articularis Rubiaceae
Bridelia stipularis Euphorbiaceae
Commelina spp. Commelinaceae
Crassocephalum
crepideoides
Compositae
Crotalaria pallida
Papilionaceae
Dalbergia stipularis Leguminosae
Dryopteris spp
Glycosmis spp Rutaceae
Hedyotis scendans Rubiaceae
Ludwigia repens Onagraceae
Merremia vitifolia Convolvulaceae
Mucuna spp Papilionaceae
Thysanolaena maxima Graminae
Algash
Arkila Ixora nigricans Rubiaceae
Asamlata Mikania cordata Compositae
Bash ghass Graminae
Chotrapata Flaria interapta Articaceae
Croton Croton bonplandianum Euphorbiaceae
Dul kolmi Ipomea carnea Convolvulaceae
Dumur Ficus hispida Moraceae
Ghotkochu Typhonium trilobata Araceae
Ghuruchea Combritum spp Combretacea
Horina /Horinna
Gota
Vitex peduncularis Verbenaceae
Kantabegun Solanum torvum Solanaceae
Lantana Lantana camara Verbenaceae
139
Ludwigia
adscendens L.
Ludwigia adscendens Onagraceae
Malastoma /Indian
Rhododendron
Melastoma malabathricum Melastomataceae
Shornalata Cuscuta reflexa Cuscutaceae
Ulu son Saccharum spontaneum Cramineae
Son Imperata cylindraca Verbenaceae
Vitex Clerodendrum viscosum Verbenaceae
8.1.5.3 Lantana (Lantana camara)
Family: Verbanaceae
Vegetative characteristics: Lantana camara is a bushy spreading, tangled,
multibanched, and thicket-forming perennial shrubt. Stem hairy, cylindrical. A one-year-
old Lantana bush contains 12-20 mature stems when counted at the basal part. Each
individual stem again gives rise to several branch as the height of the bush increases.
Ultimately the whole area near the bush base is covered by Lantana. If the bush/stems gets
support, then they climb higher which may extend up to 5-7m. If they don’t get the
support (e.g. electric post, fence, tree etc.), the bush height remains within 1.5-2.0m and
spreads laterally. Leaves opposite, ovate-deltoid to triangular-oblong, coarsely serratedat
the margin, conspicuously nerved, strongly smelled and hairy. Leaves are non-palatable to
animals. A mature stem is white or brown white, at younger stage it is green. A mature
Lantana stem is hard and turn woody. Yellow, deep yellow and pick coloured bunchy
flowers are seen to bloom in Lantana plant. Sometimes all those three-colour combination
can be found on one flower while they may be found separately on others.
Habitat: It is a common weed of wasteland, agricultural lands roadsides and
borderland of forest in Bangladesh. It is found in all the districts in Bangladesh.
Growth: Growth of Lantana camara is 22cm per month on an average.
Biomass: In 2m by 2m sample plot, taken randomly from the thicket of Lantana
camara, the biomass is on average 7.70 kg. When converted to hectare, the biomass
is19250 kg per ha on sites of heavy infestation.
140
Mode of reproduction: Lantana reproduces mainly by seeds. It also reproduces
vegetatively. Cuttings grow when they are planted in the soil. If a Lantana bush is cut, it
will resprout to original bush within a few days.
Ecological threat: A one year old Lantana bush may cover 2-2.5m radius area
completely and do not allow other plants to grow under the bush. Very few or no herbs or
shrubs are seen to grow through a Lantana bush. Soil remains exposed under a complete
Lantana bush. Spines are found in the Lantana stem. So movement is problematic through
Lantana infested habitat. Animal movement through Lantana bush seems to be very
problematic. This shows clearly that Lantana is a aggressive and invasive plant which
suppresses indigenous plants to grow near or under it.
Table 20: Some of the allied species, which grow over the Lantana bush or near it.
Local Name
Scientific Name Family
Ageratum conyzoides Compositae
Commelina spp. Commelinaceae
Crassocephalum
crepideoides
Compositae
Crotalaria pallida
Papilionaceae
Dalbergia stipularis Leguminosae
Dryopteris spp
Glycosmis spp Rutaceae
Ludwigia repens Onagraceae
Mucuna spp Papilionaceae
Thysanolaena maxima Graminae
Algash
Asamgash Eupatorium odoratum Compositae
Asamlata Mikania cordata Compositae
Bash ghass Graminae
Chotrapata Flaria interapta Articaceae
Croton Croton bonplandianum Euphorbiaceae
Dumur Ficus hispida Moraceae
141
Ghotkochu Typhonium trilobata Araceae
Kali kochi shak Vigna spp. Leguminosae
Khosh khoshia lata Byttneria pillosa Sterculiaceae
Koloi lata Coccinea cordifolia Cucurbitaceae
Malastoma /Indian
Rhododendron
Melastoma malabathricum Melastomataceae
Son Imperata cylindraca Verbenaceae
Ulu son Saccharum spontaneum Cramineae
Fig: Lantana.
142
8.1.5.4. Dul kolmi (Ipomoea carnea).
Family: Convolvulaceae
Vegetative characteristics: Ipomoea carnea is a perinnial shrub with hard stem,
greener at the top portion and gray coloured at the base. Stem is cylinderical. Ipomea
carnea can become 3-4 m tall. Leaves are long cordate shaped with 20-25 rives steming
from the mid rib. White powdery substance present on the older leaves. From main
branch, a few sub-branches come out specially horizontal stems touching the soil. Flowers
are off white, funnel shaped, petals jointed. Flowers come from the stem nodal upper base
of the leaves.
Habitat: It is a Common weed of all habitats In Bangladesh. Can come up in
waterlogged areas. Widely seen in roadside and farm ditches, waterlogged areas,
shorelines, river-sides. In Bangladesh it is seen in almost all districts Ipomoea carnea
grows well in wet areas. Canal sides, creek sides, road sides, railway sides, pond
embankment, river sides etc wet places are most affected by Ipomea. Agricultural and
wastelands whether they are wet or not are also affected by Ipomea.
Growth: Growth of Ipomoea carnea is 43.5cm per month.
Ecological threat: Invasiveness of Ipomoea carnea has been obvious because of
their rapid expansion and widespread detrimental ecological impacts. From the field
survey it was found occurrence of Ipomea as a problematic weed in nearly all moisture
rich habitat. Ipomea was seen affecting badly indigenous biodiversity by suppressing and
displacing the nearby plants by its massive self growth. This is non-palatable to animals.
143
Vegetative growth is too much successful. Ipomea along with other invasives like Mikania
cordata, Eupatorium odoratum, Imperata cylindraca, Eichhornea carassipes invades the
ecosystem badly in Bangladesh. Water channels are sometimes mostly occupied by
Ipomoea and Eichhornea carassipes that obstructs water flow. It is a frequent weed in
waste lands in Bangladesh.
Table 21: Some of the allied species found growing with Ipomoea carnea
Local Name
Scientific Name Family
Adiantum lessata
Ageratum conyzoides Compositae
Axonospora cylenga
Borreria articularis Rubiaceae
Cyperus spp Cyperaceae
Dryopteris spp
Glycosmis spp Rutaceae
Gymnema acuminatae Asclepediaceae
Hyptis suaveolens Lamiaceae
Leucas aspera Labiatae
Ludwigia repens Onagraceae
Mucuna spp Papilionaceae
Pistia strateoties Araceae
Polygonum spp
Premna esculenta Verbenaceae
Thysanolaena maxima Graminae
Asamgash Eupatorium odoratum Compositae
Asamlata Mikania cordata Compositae
Bash ghass Graminae
Bishkatali Polygonum lanatum Polygonaceae
Chotrapata Flaria interapta Articaceae
Croton Croton bonplandianum Euphorbiaceae
Kochuripana Eichhornea crassipes Pontederiaceae
144
Malastoma/Indian
Rhododendron
Melastoma malabathricum Melastomataceae
Son Imperata cylindraca Verbenaceae
Ulu son Saccharum spontaneum Cramineae
Fig : Ipomea
145
8.1.6. Comparison of invasiveness among Mikania cordata,
Eupatorium odoratum, Ipomoea carnea and Lantana Camara:
All these species were found to create massive destruction to forests and agricultural
lands in Bangladesh. The growth of Mikania cordata was 220 cm per month, Eupatorium
odoratum 45 cm per month, Ipomoea carnea 43.5cm per month and Lantana Camara
22cm per month. Mikania cordata and Eupatorium odoratum showed massive growth and
reproduction followed by Ipomoea carnea and Lantana Camara. They all can be
rigorously blammed for suppressing and displacing indigenous vegetation by their massive
growth and reproduction. From practical field investigation and observation, the four
species, on the basis of their level of destruction, Mikania cordata is the worst weed
followed by Eupatorium odoratum, Ipomoea carnea and Lantana Camara.
8.1.7. Limitations of the study
Quantitative evidence for the loss of biodiversity due to invasive plants was
assessed from paired sample plot surveys, where native species abundance,
richness or diversity was compared between areas under indigenous trees and
146
invasive trees. These observations are problematic because differences in
biodiversity between the invaded and uninvaded areas may be related to other
factors beside invasion. For example, the sites may have differed in diversity long
before the alien plants arrived.
In the present studie, species diversity was not surveyed in the sample plot before
and after an invasion. As with the paired plot studies, direct effects of alien plants
on native biodiversity may be overestimated if an external factor, like disturbance,
biotic factors, micro climate, nutrient status, microbial activity etc. may affects the
paired plots differently.
Careful monitoring of study sites over long time is needed to eleminate the
external factors that have had important effects on diversity in the study site, but
these could not be done for shortage of time. That’s why the present data might
have some biasness and therefore, the accuracy of the result might have some
corruptions.
Local names or scientific names of many plants could not be known. That’s why
in some cases they could not be presented to the result. Biasness in data analysis
and inaccuracy in the result might originate from this.
The paired sample plots were not exactly identical in all aspect, because finding
that type of site is difficult unless they are created. They might differ, at least to
some extent in slope, aspect, altitude etc. So undergrowth vegetation in the sample
plots may be affected by other external factors beside biological invasion.
8.1.8. Recommendations
The impacts of alien invasive species may be immense, insidious, and usually
irreversible. They may be as damaging to native species and ecosystems on a
national and global scale as the loss and degradation of habitats. So, policy makers,
biologists, foresters, silviculturists, entomologists, zoologists, botanists, naturalists,
scientists of various research organizations (e.g. Forest Department, Bangladesh
Rice Research Institute, Department of Fisheries, different NGOs working with
environment and biodiversity) and civil society should be aware of biological
147
invasion in Bangladesh and formulate appropriate measures unitedly so as to tackle
the problem of biological invasion or at least, halting it from further deterioration.
We should undertake surveys and research to assess the extent to which indigenous
or native species are already invaded by alien species and assess the economic
implications of these invasions. The findings of such studies need to be much more
widely publicized or broadcast and in particular must be brought to the attention of
government planners and regulators so that actions can be taken to control or
eradicate the alien invasive plants.
National databases about alien invasives should be established . Such databases
should list recognized invasives, give case studies of levels of damage and of
control measures employed.
Raising awareness of the IAS problem and potential solutions through relevant
organizations and frameworks at national level. Creating linkages among
governments and the private sector, and across disciplines; hosting workshops on
strategic planning, priority setting, and the development of new and better tools to
address invasive alien species problem.
Summarizing scientific and technical information of the alien invasive plants to
make it readily available to policy makers, scientists, educators, and other
audiences to formulate steps to be taken against invasive species.
Indigenous species should be given preferences in plantation programs first. If the
native species are not able to provide the required productions, than the exotics
may be considered for plantations only. Extensive studies should also be carried
out by scientist, botanists and foresters on further effect of these species in the
ecosystem.
In case of intentional introduction, judicious manipulation of the matters should be
done regarding the actual necessity of introduction of that plant, the past history of
invasiveness of the plant to the country of its native origin or to other country,
insects and pests associated with the alien plants, if becomes invasive in future
here in Bangladesh, their possible control method should be specified to reduce
future degradation of the environment. If the species show sign of biological
invasion to other countries, they must be discarded to introduce in Bangladesh.
148
Should develop institutional mechanism, to reach decisions on whether proposed
introductions should be authorized, to develop import and release guidelines and to
set specific conditions for alien plants where appropriate.
Give utmost importance to effective evaluation and decision-making processes
during plant introduction. Carry out an environment impact assessment and risk
assessment as part of the evaluation process before coming to a decision on intro-
ducing an alien species.
Where relevant, require that specific experimental trials (e.g. to test infectivity of
alien species) be conducted as part of the assessment process. Such trials are often
required for biological control proposals and appropriate protocols for such trials
should be developed and followed.
Criminal penalties and civil liability for the, consequent eradication or control costs
of unauthorized intentional introductions can be developed.
Quarantine rules should be strictly followed for the plants imported from overseas
by authorized institutions. Quarantine and border control regulations and facilities
should be put in place and train staff to intercept the unintentional introduction of
alien species. Quarantine and border control regulations should not be premised
only on narrow economic grounds that primarily relate to agriculture and human
health, but, in addition, on the unique biosecurity threats each country is exposed
to.
Preventing the introduction of alien invasive species would be the cheapest, most
effective and most preferred option and warrants the highest priority.
Rapid action to prevent the introduction of potential alien invasives is appropriate,
even if there is scientific uncertainty about the long-term outcomes of the potential
alien invasion.
The intentional introduction of an alien species should only be permitted if the
positive effects on the environment outweigh the actual and potential adverse
effects. This principle is particularly important when applied to isolated habitats
and ecosystems, such as islands forests.
The intentional introduction.of an alien species should only be considered if no
native species is considered suitable for the purposes for which the introduction is
being made.
149
Unfortunately, it can be very difficult to control unintentional introductions that
occur through a wide variety of ways and means. Identification and management of
pathways leading to unintentional introductions should be maid. Important
pathways of unintentional introductions include: national and international trade,
tourism, shipping, ballast water, fisheries, agriculture, construction projects,
ground and air transport, forestry, horticulture, landscaping, pet trade and
aquaculture.
Efforts should focus on building a distributed information system by linking
national and international databases and overall information on the issue of
invasive alien plants. Efforts at the notional level should: Reviewing relevant
policies, legislations and institutions to identify conflicts, gaps and inconsistencies;
and strengthen or develop effective national measures for the prevention,
eradication, and control of alien species.
Active public engagement is critical to successful invasive plant management.
State and organizations working with forest and environment should work to
motivate the public successfully regarding the negative impact of invasive alien
plants on environment and coordinate their efforts for greater national benefit,
leading to an informed public that supports actions to reduce the threat of the alien
plants.
Preventing the introduction of alien invasive species should be the first goal. When
prevention has not been successful, steps to mitigate adverse impacts of invasive
plants may include eradication, containment and control. Eradication, containment
and control method for invasives like Eupatorium odoratum, Mikania cordata,
Lantana camara, Eichhornea crassipes, Ipomea carnea Ageratum conyzoides,
Ludwigia adscendens, Imperata cylindrica etc. should be developed through
research. Early detection of new introductions of potential or known alien invasive
species, together with the capacity to take rapid action, is often the key to
successful and cost-effective eradications.
Expert advice should be sought regarding eradication, control, or containment of
invasive plants where appropriate. A multidisciplinary approach might be best, as
recommended in the IUCN Guidelines for invasive species.
150
Control methods should be socially, culturally and ethically acceptable, efficient,
non-polluting, and should not adversely affect native flora and fauna, human health
and well-being, domestic animals, or crops.
Increase the exchange of information between scientists and management agencies,
not only about alien invasive species, but also about control methods.
For Eupatorium odoratum, Mikania cordata, Lantana camara, and Ipomea carnea
spread should be checked to save our forests, agricultural lands and waste lands
from their invasion. All these species are spreading naturally by their massive
reproduction and growth. Control by mechanical means may prove best to check
their spread. It would be feasible to slash and burn the weeds. Regular monitoring
of the infested sites should be done.
Plantation of Acacia auriculiformis and Eucalyptus camaldulensis in Bangladesh
may be planted in limited scale in the degraded sites where performance of local
species is poor. After the site condition has improved much after a certain period,
they should be replaced by native species even though the performances of the
natives are poor. The nominal loss of some amount of timber or fuel wood would
be easily compensated by long-term ecological balance and biodiversity
conservation imparted by the native plants. It can be recalled here that Government
of Bangladesh has already banned planting of Eucalyptus in Bangladesh, but
people are still planting Eucalyptus because of ignorance.
Plantation of Melaleuca leucodendron can be done in limited scale for ornamental
purpose only. Large scale plantation of Melaleuca leucodendron can be discarded
as this tree has already been leveled as invasive tree in different countries of the
world (particularly in Florida, USA) although no marked effect of Melaleuca was
observed from the research result.
151
Conclusion It is acknowledged that invasive species are one of the major threats to biological
diversity worldwide. Invasive alien species are an enormous threat to plant and diversity,
as well as to the economy of many countries and the well being of their people.
Bangladesh is also facing the problem of invasive alien species, which are introduced
deliberately or have spread naturally to our environment. Countering this threat and
saving our valuable native plant and animal biodiversity from their threat is likely to
become a huge challenge for Bangladesh, and the costs would be significant. However,
the costs of ignoring the problem will be almost incalculable - lost agricultural
production, spoiled crops, human disease and allergies, clogged catchments and water
bodies, reduced water availability, threatened rural livelihoods, disrupted ecosystem
services, and species extinctions.
Exotic species are playing a vital role in the plantation forestry of Bangladesh. Due to not-
well-thought-out government policies, weak enforcement of existing safeguards, and lack of
popular awareness, alien invasive species are taking over natural habitats and rapidly changing the
native character of the ecosystem. It is quite unfortunate that the long-term, and even short-term,
adverse effects were not considered while introducing these alien invasive species to Bangladesh.
Apart from providing ecological balance the adverse impacts on native biodiversity can be reduced
if introduction and spread of alien invasive species are stopped.
Combating alien invasive species in Bangladesh will be very difficult because of lack of
awareness and proper initiatives. The selection of species for the introduction in the plantation
must be done very carefully. No species should be introduced without adequately evaluating their
detailed life history, probable impacts and probable benefits in Bangladesh. Any further
introduction of such species must be stopped. People should be made aware of the negative
consequences of introducing alien species and the true values of sustaining and reviving the
indigenous species. Bangladesh is rich enough in biodiversity. We have almost all the major types
of flora and fauna with the characteristics of high growth rate, high economic value, high market
demand, etc. hence, it would be more prudent if the concerned authorities could try to improve and
popularize these indigenous species instead of indiscriminately introducing alien invasive species.
People should be motivated to cultivate indigenous species. Necesssry action should be taken for
the naturally spreading species like Lantana camara, Eupatorium odoratum, Ipomea carnea
Mikania cordata, Ageratum conyzoides, Imperata cylindrica, Eichhornea crassipes, Pistia
strateotes etc. to eradicate them from the country or if not possible, to at least reduce their massive
spread in the environment. The enormous scale of threat from IAS is under appreciated in
Bangladesh. Bangladesh should take the problems of alien invasives more seriously. It is high time
that Bangladesh develops suitable methods and policies to deal with invasive alien species.
152
References
Akerson, J. (2003). ALIENS. Invasive Species Specialist Group (ISSG) of the IUCN
species survival commission, 17: 1-13.
Ali, M. (1996). Status aspects and environmental consideration of Eucalyptus planting in
Bangladesh. In:White, K.,Ball, J.and Kashio, M.(eds). Proceedings of the regional
expert consultation on Eucalyptus, 4- 8 october 1993. Volume-1. FAO Regional
Office for Asia and the Pacific, Bangkok.9p.
Allan, H.H. 1936. Indigene versus alien in the New Zealand plant world. Ecology 17: 187-
192.
Alleaume, B. M., Ophelie, R. and Idopen. (2003). Dispersal, drift and local adaptation in
fragmented population. Abstracts: Invasive Plants in Natural and Managed
Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 4p.
Allendorf F. W., Leary R. F., Spruell P. and Wenburg J. K. (2001). The problems with
hybrids: setting conservation guidelines. Trends in Ecology and Evolution, 16:
613-622.
Allesh, S., Hisham, J. and Priyadarsanan, R. (2003). Impact of invasive species, Lantana
camara L. (Verbenaceae) on ground insect diversity in dry and moist deciduous
forests of BRT wild life sanctuary, India. 5p.
Ameen, M. 1999. Development of Guiding Principles for the Prevention of Impacts of
Alien Species. Paper presented at a consultative workshop in advance of the 4th
Meeting of SBSTTA to the CBD, organised by IUCN Bangladesh at Dhaka on May
25 1999.
Andreasen, J. K. (2001). Modeling Species Invasions: New Methods and New Data from
Biodiversity. Assessment and Management of Alien Species that Threaten
Ecosystems, Habitats and species. UNEP Secretariat of the Convention on
Biological Diversity. 107p.
Anon. (1984). Leucaena: Promising Forage and Tree crop for the Tropics. National
Academy Press, Washington, D.C.
Anon, (2002). Asian Biodiversity (The news magazine of the ASEAN regional centre for
biodiversity conservation), 2(4): 60-69.
Anon, (2003). Understanding Invasive Aquatic Weeds. Aquatic plant management society,
U.S.A., 16p.
153
Anon. (2003). Invasive species initiative of The Nature Conservency.3p.
Aston, P. J. and Michell, D. S. (1989). Aquatic plants: Patterns and modes of invasion,
attributes of invading species and assessment of control programmes. In: J. A.
Drake, H. A. Money, F. di castri, R. H. Groves, F. J. Kruger, M. rejmanek and M.
Williamson, (eds.), Biological Invasions: A Global Perspective, John wiley and
sons, Chichester : 111-154.
Baksha, M. W., and Islam, M. R. (1994). Invasion of Ipil-Ipil psyllid in Bangladesh and its
control. Bangladesh Journal of Forest Science. 23(1): 35-36.
Ball, J.B. (1995). Development of Eucalyptus plantations-an overview. In:White, K.,
Ball,J.and Kashio,M.(eds).Proceesings of the regional expert consultation on
eucalyptus, 4- 8 October 1993. FAO regional office for asia and the
pacific,Bangkok, 1: 15p.
Balogh, L. and John, P. B (2003). Species of the genus Fallopia sectio Reynoutria in
Hungary – a land of the hybrid Fallopia x bohemica, 5p.
Banks, J. C. G. (1992). Personal Communication. Lecturer, Department of Forestry,
Scholl of Resource and Environmental Management, The Australian National
University.
Barretts, S.C.H. (1980). Sexual reproduction in Eichhornia crassipes (water hyacinth). 11.
Seed production in natural populations. Journal of Applied Ecology, 17: 113-124.
Bhuiyan, M. K. (1986). Effect of Initial Spacing on the Survival and Growth of
Eucalyptus. Chittagong University Studies, Part 11: Science, 10 (1&2): 115-121.
Binggeli, P., and Hamilton, C. 1993. Biological invasion by Maesopsis eminii in the East
Usambara forets, Tanzania. Opera Bot.121: 229-235.
Biswas, S. R. (2003). Ecological impacts of invasive plants in Sunderbans mangroves.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 10p.
Blair, R. B. 1996. Land use and avian species diversity along an urban gradient. Ecol.
Appl. 6: 506-519.
Bosdtid. (1984). Promising forage and trees crop for the tropics. National Academy Press.
100 p.
Brisson, J., Alain, C. and Michel, R. (2003). Controlling Speckled Alder (Alnus rugosa) invasion
in a wetland reserve of southern Quebec. Abstracts: Invasive Plants in Natural and
Managed Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant Invasions.
November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida.11p.
154
Brook, R.M. (1989). Review if literature on Imperata cylindrica (L.) Raeuscel with
particular reference to South East Asia. Tropical Pest Management, 35:12-25.
Brown, N. (1997). Re-defining native woodland Forestry 70(3): 191-198.
Browne, M. and Maj, D. P. (2003). The Global Invasive Species Database (GISD). 12p.
Bruner, M.C. (1982). Water-lettuce, Pistia stratiotes L. Aquatics 4: 4-14.
Bryson, C.T. and Carter, R. (1993). Cogongrass, Imperata cylindrica, in the United States.
Weed Technology 7: 1005-1009.
Campbell, G. S., P. G. Blachwell, and F. I. Woodward. (2002). Can landscape- scale
characteristics be used o predict plant invasions along rivers? Journal of
Biogeography, 29:535-543.
CBD, (2001). Review of the Efficiency and Efficacy of Existing Legal Instruments
Applicable To Invasive Alien Species. CBD Technical series no 2, Secreteriat of
the Convention on Biological Diversity(CBD), world trade centre, 393st.Jacques
street, suit 300, Montreal, Quebec, Canada.31p.
Center, T.D. and Van, T. K. (1989). The phenology and growth of waterhyacinth
(Eichhornia crassipes (Mart.) Solms) in a eutrophic morth-central Florida lake.
Aquatic Botany 10: 1-32.
Chowdhury, A. (2003). Ecological impacts of invasive plants: Bangladesh perspective.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 18p.
Chowdhury, J. A. (1993). Final Report of the Resource Survey Consultant. Thana
Afforestation and Nursery Development Project, Bangladesh.
Christopher, K. J. (2001). Lantana a poisonous plant. SAIC Newsletter.11 (2): 7p.
Clark, D. W. and Randall, K. S. (2003). Invasive exotic plants in natural areas of the
Caribbean Basin: Quantifying ecological effects and forming management
partnerships. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
the Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida.18p.
Clout, M. D. (2003). International initiatives against invasive species. 18p.
Coblentz, B. (1990) Exotic organisms; a dilemma for conservation biology. Conservation
Biology, 4:261-265.
Cock, M., Day R., Herren H., Hill M., Juline M., Neuenschwander P.and Ogwang
J.(2000). Harvesters get that sinking feeling. Biocontrol News and Information
21(1): 1-8.
155
Committee for Investigating the Effects of and Contermeasures against riparian Exotic
Species (2003) Principles and Examples of Exotic Species Control in Rivers: the
Impacts and Control of Major Invasive Exotic Species, Foundation for riverfront
Improvement and restoration, Tokyo (in Japanese).
Courteau, J. B. (2003). Why species interactions are important for understanding and
managing species invasions. Abstracts: Invasive Plants in Natural and Managed
Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 19p.
Courtney, A. and Perkins, C. L. (2004). Fighting invasive species in the courts. The
potential applicability of United States tort law (nuisance and trespass) to address
invasive species issues and how such efforts can be strengthened through the use of
statutory law. Program and Abstracts: International Conference on Assessment and
control of biological invasion risks. August 26-29, 2004, Education & Cultural
Hall, Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama, Japan.
46p.
Cousens, J.E., (1963). Variation of some diagnostic characters of the sessile and
pedunculate oaks and their hybrids in Scotland. Watsonia 5: 273-286.
Cronquist, A. (1988). The Evolution and Classification of Flowering Plants, 2nd edition,
New York Botanical Garden, New York.
Crooks, J. (2004). The arrival, establishment and integration of an invasive marine mussel
into foreign ecosystems. Program and Abstracts: International Conference on
Assessment and control of biological invasion risks. August 26-29, 2004,
Education & Cultural Hall, Yokohama National University Tokiwadai, Hodogaya-
ku, Yokohama, Japan. 54p.
Crooks, J. A. and M. E. Soule, (1999). Lag times in population explosions of invasive
species: causes and implications. In O.T. Sandlund et al. (eds), Invasive Species
and Biodiversy Management, Kluwer Academic Publishers: 103-125.
D’antonio, C. M. (2003). Introduction and historical perspective on ecological resistance.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 20p.
D’antonio, C. M., Flint, H.R., Mack, M, Hitchcock, d., and Vitousek, P.M. (1998). The
response of native species to removal of invasive exotic grasses in a seasonally dry
Hawaiian woodland. J.veg. Sci, 9: 699-712.
Dabral, B. G., Pant, S. P., Pharasi, S. C. (1987). Root habits of Eucalyptus – Some
Observations. The Indian Forester, 113(1):11-32.
156
Daehler, C. C. and Carino D A. (1999). Threats of invasive plants to the conservation of
biodiversity.In: Chou, C.H, Waller G. R., and Reinhardt, C (eds). Biodiversity and
allelopathy. pp 21-27.
Das, S. (1982). Introduction of exotics in the plantation Forestry of Bangladesh. Proc.
Second Bangladesh National conference on Forestry: 85-93.
Das, S. (1984). Nursery and Plantation Technique for Acacia mangium, Bulletin 3,
Silvicultural Research Division, Bangladesh Forest Research Institute, Chittagong.
35p.
Das, S. (1984). Nursery Techniques for Eucalyptus Species. Bangladesh Forest Research
Institute. Silviculture Division Bull. 1: 34p.
Das, S. (1985). Nursery and plantation technique for Acacia auriculaeformis Bull No. 7.
Silviculture Research Division. Bangladesh Forest Research Instiute, Chittagong.
28 p.
David, M.E (2002). Siam Weed. Asean Biodiversity. 2(4): 68p.
Davidson, J. (1985). Ecological and social aspects of Eucalypts when used as exotics. In:
Eucalypts in Bangladesh: a review. Silviculture Division, Bulletin No. 6, BFRI,
Chittagong: 13-48.
Davidson, J. (1993). Overview of the Regional Symposium on Recent Advances in Mass
Clonal Multiplication of Forest Trees. In: Regional Symposium held 1-8 December
1992, Cisarua, Bogor Indonesia. Field Documents No. 4, Project UNDP/FAO
RAS/91/004, FAO, Los Banos, Philippines.
Davidson, J. and Das S. (eds.) (1985). Eucalypts in Bangladesh: a review. Silviculture
Division, Bulletin No. 6, BFRI, Chittagong: 246p.
Davidson, J., Das, S. (1985). Chronology of Eucalyptus Introduction in Bangladesh in
Eucalyptus in Bangladesh, Davidson, J. and S. Das (ed.). A review. Silviculture
Division Bull. No. 6. Bangladesh Forest Research Institute, Chittagong: 91-104.
Davis, M. B. (1989). Lags in vegetation response to greengouse warming. Climate Change
15: 75-82.
Decamps, H. (1993). River margins and environmental change. Ecological Applications,
3:441-445.
Downey, P. O. (2003a). Invasive species and plant conservation: woody weeds, In: C.L.
Brown, F. Hall &J. Mill (eds) Plant Conservation: approaches and techniques
from an Australian perspective. Module 4 (pages unnumbered), Australian
Network for Plant Conservation, Environment Australia, Canberra.
Downey, P. O. (2004). Bitou bush management and plant conservation: establishing
priorities for control. In: B. M. Sindel & S. Johnson (eds) The Proceedings of the
157
14th Australian Weeds Conference. Pp. in press, R. G. & F.J. Richardson,
Melbourne.
Dozier, H., Gaffney, J. F., McDonald, S. K., Johnson, E. R. R. L. and Shilling, D.G.
(1998). Cognograss in the United States: History, ecology, impacts, and
management. Weed Technology, 12: 737-743.
Drake, J. A., Di Castri, F., Groves, R., Kruger, F., Mooney, H., Rejmanek, M. &
Williamson, M. (Eds). (1989). Biological invasions: a global perspective. John
Wiley & Sons Ltd.
Dree, L.R. (2003). Invasive Species Specialist Group (ISSG) of the IUCN species survival
commission. ALIENS, 17: 7p
Dukes, J. S. (2003). Effects of climate change on the success of invasive plant species.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 25p.
Duncan, C.L., John, J. J., Vanellef, C., Joseph, M. D., Rodney, G. L., Kirk, C. M., Mark J.
R., and Peter M. R. (2003). Assessing economic, environmental, and societal
losses from invasive plants on rangeland and wildlands. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on the Ecology and Management
of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida 25p.
Ecological Society of Japan (2002) Handbook of Alien Species in Japan. Chijinshokan,
Tokyo (in Japanese).
Ehrenfeld, J.G. (2003). Challenges in restoring soils altered by exotic plant invasions.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida, 26p.
Eldridge, K., Davidson, J., Harwood, C. and Van Wyk, G. (1993). Eucalypt Domestication
and breeding. Claredon Press, Oxford. 288 pp.
Ellstrand, N. and Kristina A. S. (2003). Hybridization as a stimulus for the evolution of
invasiveness in plants? Abstracts: Invasive Plants in Natural and Managed
Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida.26p.
Eplee, R. E. (2003). Overview of the invasive plant problem – Rationale for weed
prevention. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
158
Science and Management in conjunction with the 7th International Conference on
the Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida 27p.
FAO (1995). Forestry statistics – Today for Tomorrow. Forestry Department, Viale delle
Terme di Caracala, Room. 52pp.
FAO. (1981). Eucalypts for planting, FAO Forestry Bulletin, FAO, Rome, 677 p.
Fenster, C.B., Dudash, M.R., 1994. Genetic consideration for plant restoration. In:
Bowels, M.L., Whelan, C.J. (Eds.), Restoration of Endangered Species, Cambridge
University Press, Cambridge: 34-62.
Ferreira, J., Ana Pereira, J. and Martins-Loucao M.A. (2003). The invasive success of
Acacia species in coastal dune ecosystems of Portugal. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on the Ecology and Management
of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida. 29p.
Florence, R. G. (1992). Personal communication. Reader, Department of Forestry, School
of Resource and Environmental Management, The Australian National University.
Florence, R.G. (1990). Perceptions of the eucalypt as an exotic: an ecological
interpretation. International Symposium on Ecualyptus, November 1990,
Zhanjiang, China, 21 p.
Fuller, P. L., Nico L. G. and Williams J. D. (1999) Nonindigenous fishes introduced into
inland waters of the United States. American Fisheries Society, Special
Publication 27, Bethesda, Maryland.
Garrott, R.A., White, P.J., Vanderbilt White, C.A., (1993). Over-abundance: an issue for
conservation biologists? Conservation Biol. 5: 283-296.
George, M. (1986). Nutrient uptake and cycling in young E. hybrid plantations. Myforest
22 (1): 22-26.
Gilbert, O.L., Anderson, P., (1998). Habitat Creation and Repair. Oxford University
Press, Oxford.
Gollasch, S. (2004). Risk assessment approaches and their management implications to
avoid species invasions with ballast water. Program and Abstracts: International
Conference on Assessment and Control Of Biological Invasion Risks. August 26-
29, 2004, Education & Cultural Hall, Yokohama National University Tokiwadai,
Hodogaya-ku, Yokohama, Japan. 55p.
Gopal, B. (1987). Water Hyacinth. Elsevier, New York.18p.
Gould, W. and Walker M. (1997). Landscape-scale patterns in plant species richness
along and Arctic River. Canadian Journal of Botany, 75:1748-1765.
159
Gowanloch, J. N. and Bajkov. A. D. (1948). Water hyacinth program, Louisiana
Department of Wildlife and Fishries, Biennial Report (1946/1947) 2: 66-124.
Gowanloch, J.N. (1944). The economic status of the waterhyacinth in Louisiana.
Louisiana Conservationist 2: 3-8.
Gregorio, I. (2002). Invasive Alien species and their Impact on Biodiversity. Asean
Biodiversity, 2(4): 8p.
Grime, J. P. (1977). Evidence for the existence of three primary strategies in plants and its
relevance to ecological and evolutionary theory. American Naturalist, 111: 1169-
1194.
Grime, J. P. (1979). Plant Strategies and Vegetation Process. Wiley, New York.
Haigh, J.C. (1936). Notes on the water hyacinth (Eichhormia crassipes Solms) in Ceylon.
Ceylon Journal of Science, 2(2): 97-108.
Hammar, R. (2003). Prohibited Plant Species. Department of Environmental
Resource Management,U.S.A. 31pp.
Hansen, K.L., Ruby E.G. and Thompson R.L. (1971). Trophic relationship in the water
hyacinth community. Quarterly Journal of the Florida Academy of Science 34(2):
107-113.
Harding P.T. and Rose F. (1986). Pasture Woodlands in Lowland Britain. Institute of
Terrestrial Ecology, Abbots Ripton. 45p.
Harley, K.L.S. (1990). The role of biological control in the management of water hyacinth,
Eichhornia crassipes. Biocontrol News and Information 11(1): 11-22.
Harold, M. (2001). Invasive Alien Species – the Nature of the problem. CBD Technical
Series No. 1. Assessment and Management of Alien Species that Threaten
Ecosystems, Habitats and species. UNEP. Secretariat of the Convention on
Biological Diversity: 1-2pp
Hassan, M. M. (1994). Prospects of Eucalyptus in Bangladesh. Bangladesh Journal of
Forest Science. 23(1): 12-17.
Heywood, V. H. (1989). Patterns, extents and modes of invasions by terrestrial plants,
In:J. A. Drake, H. A. Mooney, F. Di castri, R. H. Groves. F. J. Kruger, M,
Rejmanek and M, Williamson, (eds.), Biological Invasions: 31-60.
Hitchcoch, A.E., Zimmerman P.W., Kirkpatrick H. and Earle T.T.(1950). Growth and
reproduction of water hyacinth and alligator weed and their control by means of 2,
4-D. Contribution of the Boyce Thompson Institute, 16(3): 91-130.
Hitchmough, J. and Dunnett N. (1996). Sustainable Schemes. Landscape Design 251: 43-
46.
Holm, L.G., Plucknett D.L., Pancho J.V., and Herberger J.P. (1977). The World’s Worst
Weeds: Distribution and Biology, Honolulu, Hawaii.
Holm, L.G., Weldon L.W. and Blackburn R.D. (1969). Aquatic weeds, Science. 166: 699-
709.
160
Holmes, P.M., and Cowlin, G. R, M. (1997b). Diversity, composition and guild structure
relationship between soil-stored seed banks and mature vegetation in alien plant
invaded South African fymbos shrublands. Plant Ecol.133: 107-122.
Hood, W. G. and R. J. Naiman (2000). Vulnerability of riparian zones to invasion by
exotic vascular plants. Plant Ecology, 148:105-114.
Hopmans, P., Stewart, H.T.L., Film, D.W.and Hilman, T. J. (1990). Forest Ecology and
Management, 30 (1-4): 203-211.
Hossain and Pasha. (2001). Alien invasive plants in Bangladesh and their impacts on the
ecosystem. Assessment and management of alien species that threaten ecosystems,
habitats and species. CBD technical series no 1. Secretariat of the Convention on
Biological Diversity (CBD), World Trade Centre. 75p.
Hossain, M. K. (2003). Exotic invasive plants in south-eastern hill forests of Bangladesh.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 39p.
Hossain, M. K. (2004). Biological invasion risks of introduction tree species on hill forest
ecosystems of Bangladesh. Program and Abstracts: International Conference on
Assessment and Control of Biological Invasion Risks. August 26-29, 2004,
Education & Cultural Hall, Yokohama National University Tokiwadai, Hodogaya-
ku, Yokohama, Japan. 31p.
Howard, G.2003. ALIENS. Invasive Species Specialist Group (ISSG) of the IUCN species
survival commission, 17:4.
Islam, A.K.M.N. 1991. Two centuries of plant studies in Bangladesh and adjacent
regions. Asiatic Society of Bangladesh, Dhaka, Bangladesh.
Islam, N. Q. and Neven, K. (1989). Review of Ongoing Tree Species, Elimination,
Provenance and Growth Trials of Bangladesh Forest Research Institute. Working
Paper No. 9: 46.
IUCN. (1997). Conserving vitality and diversity. In: C. D. A. Rubec & G.O. Lee (eds.)
Proceedings of the world conservation congress workshop on invasive alien
species. Canadian wildlife service, Ottawa, Canada.
IUCN. (2000). IUCN Guidelines for the Prevention of Biodiversity Loss Caused By Alien
Invasive Species. Published by ISSG as special lift out in Aliens.
IUCN. (2003). 100 of The World’s Worst Invasive Alien Species From A Selection of The
Global Invasive Species Database. Published by Invasive Species Specialist Group
(ISSG) of IUCN in contribution to the Global Invasive Species Program.11p.
161
IUCN (2003). Alien Invasive Species in Africa’s Wetland, Some threats and solutions. In:
Howard, G.W and Matindi, S.W(eds.) IUCN Eastern Africa Regional Programme,
Nairobi, Kenya.15p.
Iwasaki, K. and Katsuki, N. (2004). Invasion, range expansion and risk assessment in
aquatic systems. Program and Abstracts: International Conference on Assessment
and control of biological invasion risks. August 26-29, 2004 Education & Cultural
Hall, Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama, Japan.
53p.
Jamison, V. C. (1942). The slow reversible drying of soil beneath citrus trees in Central
Florida. Proceedings of the Soil Science Society of America 7: 36-41.
Jones, A.T. and Evans, P.R. (1994). A comparison of the growth and morphology of
native and commercially obtained continental European Cratagus monogyna Jacq.
(Hawthorn) at an upland site. Watsonia 20: 97-103.
Kabir, M. F., Bhattacharjee, D. K., Sattar, M. A. and Elias, G. N. M. 1994. Effect of
preservative treatment on strength properties of mangium (Acacia mangium).
Bangladesh Journal of Forest Science. 23(1):41.
Kandasamy, O. S., Chinnusamy, C.G. and Senthil, A. (2003). Agro-biology and
management of invasive weed Ipomoea carnea Jacq. In water ways. Abstracts:
Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 44p.
Keiji, I. and Katsuki, N. (2004). Invasion, range expansion and risk assessment in aquatic
systems. Program and Abstracts: International Conference on Assessment and
control of biological invasion risks. August 26-29, 2004, Education & Cultural
Hall, Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama, Japan.
53p.
Kendle, A.D. and Forbes, S. (1997). Urban Nature Conservation. E & FN Spon, London.
Khanna, V. 2003. Thoughts and Reflections. Invasive Species-A Threat to Endemics And
Biodiversity. Annals of Forestry. 11(1):145-153.
Kohli, R. K. and Kuldip S. D. (2003). Impact of invasive plants on structure on structure
and composition of natural vegetation of north-western Indian Himalayas.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 46p.
Koich, G., Fumio, Y. and Lynn, J. (2004). The status and future of database for invasive
alien species. Program and Abstracts: International Conference on Assessment and
162
Control of Biological Invasion Risks. August 26-29, 2004, Education & Cultural
Hall, Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama, Japan.
25p.
Koike, F. (2003). Spread speed of an invasive palm population in landscapes of
continuous and fragmented forests. Abstracts: Invasive Plants in Natural and
Managed Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 46p.
Koizumi, K. (1998). Pollinosis, In: CD-ROM World Encyclopedia ver. 1.2, Hitachi
Digital Heibonsha, Tokyo.
Latif, M. A., Habib, M. A. and Das, S. (1993). Tree vot table for A. mangium in the
plantations of Bangladesh. Bangladesh Journal of Forest Science. 182(1):23.
Latif, M. A., Khan, S. A. and Bhuiyan, M. K. (1984). The prospects of Acacia mangium
for afforestation in Bangladesh. Pakistan Journal of Forestry, 34 (4): 7-12.
Lines, R. (1987). Choice of seed Origin for the Main Forest Species. Forestry Commission
Bulletin 66, HMSO, London.
Lippincott, C.L. (1997). Ecological consequence of Imparate cylindrica (cognograss)
invation in Florida sandhill. Ph.D. dissertation, University of Florida, Gainesville,
Florida, USA.
Lisa, N. and Michelsen, A. (1993). Allelopathy in Agroforestry Systems: the Effects of
Leaf Extracts of Cupressus lusitanica and three Eucalyptus spp. On four Ethiopian
Crops. Agro-forestry Systems, 21(1): 63-74.
Lonsdale, W. M. (1994) Inviting trouble: introduced pasture species in northern Australia
Australian Journal of Ecology, 19:345-354.
Lounibos, L.P. and Dewald L.B. (1989). Oviposition site selection by Mansonia
mosquitoes on Water lettuce. Ecological Entomology 14: 413-422
Lugo, A.E. (1997). Maintaining an open mind on exotic species. In: Meffe, G.K., Carroll,
C.R., (Eds.), Principles of Conservation Biology, Sinuer Asociates, Sunderland,
Massachusetts. 245-247pp.
Luna, R.K. 1996. Plantation Trees. International Book Distributors 9/3, Rajpur Road,
Dehra Dun – 248001, India p320.
Macdonald, G., Melissa C. B. and Donn G. S. (2003). Cogongrass (Imperata cylindrical)
management utilizing integrated revegetation techniques. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 53p.
163
Macdonald, I.A.W. (1991). Conservation implications of the invasion of southern Africa
by alien organisms. PhD Thesis, University of Cape Town.
Macdonald, I.A.W.; Loope, L.L.; Usher, M.B and Hamann, O. (1989). Wildlife
conservation and the invasion of nature reserves by introduced species: a global
perspective. In: J. A. Drake, (eds), Biological Invasions: a global perspective. John
Wiley & Sons Ltd.
Mahon, P. (2000). The New South Wales Threat Abatement Plan for Predation by the Red
Fox. In: S. Balogh (ed.) Proceedings of the NSW Pest Animal Control Conference,
39-47 Pp.
Makiko, N. and Nobuo, T. (2004). Animal welfare and biological invasion: Think
individual life of alien species over! Program and Abstracts: International
Conference on Assessment and Control of Biological Invasion Risks. August 26-
29, 2004, Education & Cultural Hall, Yokohama National University Tokiwadai,
Hodogaya-ku, Yokohama, Japan. 87p.
Manuder, M. (1992). Plant reintroduction: an overview. Biodiversity and Conservation
1:51-61.
Marrs, R. A., Ruth A. H., Jorgem. V. and Harsh P. B. (2003). The effects of hybridization
and introgression on allelpathy in invasive Centaurea species. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on the Ecology and Management
of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida, 55p.
Martin, P. H., Peter L.M. and Charles D.C. (2003). Norway maple invasion of forest
stands: 4-years of seedling establishment and demography in small gaps and deep
shade. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
The Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida. 56p.
Masters, R.A. and Daniel D. B. (2003). Role of herbicides in invasive plant management
and grassland restoration strategies. Abstracts: Invasive Plants in Natural and
Managed Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida, Pp – 56.
Matsui, M., Nishiyama, K., Ogawa, Y., Shiomi, T., Yasuda, K., Okubo, T. and Suzuki, M.
(2004). The development of the Asian-Pacific Alien Species Database (APASD).
Program and Abstracts: International Conference on Assessment and control of
biological invasion risks. August 26-29, 2004 Education & Cultural Hall,
Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama, Japan. 29p
164
Matthews, L.J. 1967. Seedling establishment of water hyacinth. Pest Articles and News
Summaries (C) 13(1): 7-8.
Mauricio Florencio, P., and Cacanindin Danilo, C. (1975). Significance of research on the
ipilipil. Canopy International. 32p.
Mc Vea, C. and C.E. Boyd. (1975). Effects of water hyacinth cover on water chemistry,
phytoplankton, and fish in ponds. Journal of Environmental Quality 4(3): 375-378.
McGraw, J. M. (2003). The role of natural disturbances in conserving endangered plant
populations in an invaded plant community, central coastal California. Abstracts:
Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 58p.
Mckinney, M. L. (2003). Human population as a predictor of exotic plant species richness.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 58 p.
McNeely J. A., H. A. Mooney, L. E. Neville, P. J. Schei, J. K. Waage (editors). (2001).
Global Strategy on Invasive Alien Species Published by IUCN, Gland, Switzerland,
on behalf of the Global Invasive Species Programme (GISP). 50p.
Mealor, B. A., Ann, L. H. and Nancy, L. S. (2003). Can native plant species become
competitive with invasive exotics? Abstracts: Invasive Plants in Natural and
Managed Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 59p.
Mendoza, V. B. (1980). Producing the giant leucaena. Leucaena Forum l (I): 5 p.
Mick, C. (2003). Aliens. Invasive Species Specialist Group of the IUCN Species Survival
Commission, 18:27.
Milbau, A. and Ivan, N. (2003). An experimental study on invasiveness, invisibility and
the role of species richness during grassland invasions. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 60p.
Miller, J.H. (2003). Non-Native Invasive Plants of Southern Forests, a Field Guide for
Identification and Control. United States Department of Agriculture (USDA),
Forest Service, Southern Research Station, General Technical Report SRS-62. 51p
165
Miller, K. E., David, L. G., and Andrew, C. E. (2003). Impacts of an invasive shrub,
Lonicera maackii (Caprifoliaceae), on seedling emergence, survival and growth, of
three native perennial herb species in deciduous forest. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 60p.
Miyawaki, S. and Washitani, I. (1996) A population dynamics model for soil seedbank
plants and its application to the prediction of effects of weeding on a population of
Ambrosia trifida L. invading a nature reserve. Japanese Journal of Conservation
Ecology, 1:25-47. (in Japanese).
Money, H. A and Hobbs, R. J. (eds.) (2000). Invasive species in a changing world. Inland
press, Washington.21p.
Muranaka, T. and Washitani I. (2001). Invasion of alien grass Eragrosti curvula on the
gravelly floodplains of the Kinuriver and decrease of river endemics: necessity of
urgent measures. Japanese Journal of Conservation ecology, 6:111-122. (in
Japanese).
Myers, J. H. and Bazely, D. R. (2003) Ecology and Control of Introduced Plants,
Cambridge University Press, Cambridge Naiman, R. J., H. Decamps and M.
Pollock (1993) The role of riparian corridors in maintaining regional biodiversity.
Ecological Applications, 3:209-212.
National Academy of Scinece. (1979). Tropical legumes: Resources for the future USAID.
Nautiyal, S. Pokhriyal, T. C. and Emmanuel. J. S. K. (1994). Natural regeneration of
eucalyptus camaldulensis. Indian For. 120 (2): 174-175.
Nehrbass, N., Eckart, W. and Annette, O. (2003). Using a virtual environment to estimate
abilities and limits of ecological models to predict invasions. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 62p.
Ngobo, M. P., Stephan, F. W. and Morag, A. M. (2003). Siam weed (Chromolaena)
dominated fields in Central Africa: Farmer perceptions, biodiversity, yields and
soil properties. Abstracts: Invasive Plants in Natural and Managed Systems:
Linking Science and Management in conjunction with the 7th International
Conference on The Ecology and Management of Alien Plant Invasions. November
3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida 62p.
Nicholson, K. I. (1965). A note on Acacia auriculiformis. acunn. ex benth. in Sabah.
Malayan Forester, 28: 243-244.
166
Nobuo, I. and Mick, C. (2004). Control and eradication. Program and Abstracts:
International Conference on Assessment and control of biological invasion risks.
August 26-29, 2004, Education & Cultural Hall, Yokohama National University
Tokiwadai, Hodogaya-ku, Yokohama, Japan. 15p.
Nobuo, I. and Mick, C. (2004). Control and eradication. Program and Abstracts:
International Conference on Assessment and control of biological invasion risks.
August 26-29, 2004 Education & Cultural Hall, Yokohama National University
Tokiwadai, Hodogaya-ku, Yokohama, Japan. 15p.
O’Hara, J. (1967). Invertebrates found in water hyacinth mats. Quarterly Journal of the
Florida Academy of Science, 30(1): 73-80.
Otieno, M.O. (2003). The ecological impact of the invasive water hyacinth (Eichhornia
crassipes) on the phytoplankton community diversity in wastewater habitats in
Kenya. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
The Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida 62p.
Palanna, R. M. (1996). Eucalyptus in India. In: White,K., Ball,J. and Kashio,M. (eds).
Proceesings of the regional expert consultation on eucalyptus, 4- 8 october, 1993.
volume 1. FAO regional office for asia and the pacific, Bangkok.
Patil, M. S. and Kumar, M. D. (1990). Seed dispersion in Subabul-a case study. Indian
Forester, 116(7): 19-21.
Pattison, R. R. and Richard, N. M. (2003). Ecological constraints on the distribution of
sapium sebiferum in the southeastern USA. Abstracts: Invasive Plants in Natural
and Managed Systems: Linking Science and Management in conjunction with the
7th International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida 66p.
Pauchard, A. & Alaback, P. B. (2004). Influence of elevation, landuse, and landscape
context on patterns of alien plant invasions along roadsides in protected areas of
south-central Chile. Conservation Biology 18(1): 238-248.
Penfound, W.T. and Earle, T.T. (1948). The biology of the water hyacinth. Ecological
Monographs 18: 447-472.
Pernas, A. J., and Francois, L. (2003). The rise and fall of Melaleuca in the everglades.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 68p.
Peterjohn, W. T and K. L. Correll. (1984) Nutrient dynamics in an agricultural watershed:
observations on the role of a riparian forest. Ecology, 65:1466-1475.
167
Philip, T and Lloyd, L. (2001). An invasive species information system for Hawaii and
Pacific Islands. Assessment and Management of Alien Species that Threaten
Ecosystems, Habitats and species. UNEP. Secretariat of the Convention on
Biological Diversity. 123p.
Pokorny, M. L., Roger, L. S. and Michael, F. C. (2003). Designing invasive plant resistant
communities by maximizing niche occupation. Abstracts: Invasive Plants in
Natural and Managed Systems: Linking Science and Management in conjunction
with the 7th International Conference on the Ecology and Management of Alien
Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida 69p.
Pollock, M. M., Naiman, R. J. and Hanley, T. A. (1998) Plant species richness in
riparian wetlands: a test of biodiversity theory. Ecology, 79: 94-105.
Poore, M.E.D., Fries, C. (1985). The ecological effects of Eucalyptus. FAO Forestry
paper 59, Rome.
Poulsen, J. G. (2004). Impact of invasive species on biodiversity conservation and poor
people’s livelihoods. Program and Abstracts: International Conference on
Assessment and control of biological invasion risks. August 26-29, 2004,
Education & Cultural Hall, Yokohama National University Tokiwadai, Hodogaya-
ku, Yokohama, Japan. 52p.
Prather, T. S., Bahman, S., Lawrence, L. L., William, P., Brett, B., and Lee, E. (2003).
Which plant communities are susceptible to invasion by Centaurea solstitialis L.?
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 70p.
Primack, R. B. and Kobori, H. (1997). A Primer of Conservation Biology. Bunichisogo,
Tokyo, 398 p.
Rahel, F. J. (2002) Homogenization of freshwater faunas. Annual reviews in ecology and
Systematics, 33: 291-315.
Ranasinghe, D.M.S.H.K. and Jayasuriya, A.W.A. (1991). An investigation in to the effect
of monocultural plantations of Eucalyptus camaldulensis on soil fertility status.
Vidyodaya Journal of Science 3: 115-127.
Reichard, S. H. (2003). Identifying and mitigating pathways for invasive plants. Abstracts:
Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 74p.
Rejmanek, M. (2003). Predicting vascular plant invasiveness: An overview. Abstracts:
Invasive Plants in Natural and Managed Systems: Linking Science and
168
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida: 74-75pp.
Rhymer, J. M. and Simberloff, D. (1996). Extinction by hybridization and introgression.
Annual Review of Ecology and Systematics, 27: 83-109.
Ross, K. A. and Joan, G. E. (2003). Effects of nitrogen supply on the dynamics and control
of Japanese barberry (Berberis thunbergii) and Japanese stiltgrass (Microstegium
vimineum). Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
the Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida 77p.
Ruthrof, K.X. (2003). Ecology and control of invasive eucalypts. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on the Ecology and Management
of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida. 77p.
Salazar, R. (1988). Early genetic variation of 16 provenances of Acacia mangium in
Turrialba, Costa Rica. IUFRO Proceeding of the Workshop on Breeding Tropical
Trees: Population Structure and Genetic Improvement Strategies in Clonal and
Seedling Forestry, Pattaya, Thailand. 398-399pp.
Sankaran, K.V., Murphy, S.T., Ellison, C.A., and Sreenivasan, M.A. (2003). Mikania
micrantha in India biology and management. Abstracts: Invasive Plants in Natural
and Managed Systems: Linking Science and Management in conjunction with the
7th International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 78p
Saunders, G., Goman, B., Kinnear, J. and Braysher, M. (1995). Managing Vertebrate
Pests: foxes, AGPS, Canberra, 87p.
Sawmy, M.V (2004). ALIENS. Invasive Species Specialist Group of the IUCN Species
Survival Commission, 18, 19 &20: 11-12
Schmiz, D. C., Simberloff, R. H., Hofsetter, W. H., and Sutton, D. (1997). The ecological
impact of nonindigenous plants. In: T. C. brown, D. C. Schmitz and D. Simberloff,
eds., Strangers in Paradise: Impact and Management of Nonindigenous Species in
Florida, Island Press, Washington DC, 39-61pp.
Sculthorpe, C.D. (1967). The Biology of Aquatic Vascular Plants. Edward Arnold
Publishers, Limited, London. 1985 reprint, Koeltz Scientific Books, Konigstein,
West Germany, 43p.
Seabrook, E.L. (1962). The correlation of mosquito breeding to hyacinth plants. Hyacinth
Control Journal 1: 18-19.
169
Serbesoff-King, K. K. (2003). Review of the taxonomy, biology, harmful and beneficial
values, distribution and control of Melaleuca quinquenervia in Florida. Abstracts:
Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on the Ecology
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida, 80p.
Sewak, K. D. and Kylie, D. D. (2003). Spuring citizen involvement in invasive species
control through innovative education and outreach. Abstracts: Invasive Plants in
Natural and Managed Systems: Linking Science and Management in conjunction
with the 7th International Conference on the Ecology and Management of Alien
Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida, 80-81pp.
Sharma, B.M. (1984). Ecophysiological studies on Water lettuce in a polluted lake.
Journal of Aquatic Plant Management, 22: 17-21.
Shine, C., Willams, N and Gundling, L. (2000). A Guide to Designing Legal and
Institutional Framework on Alien Invasive Species. IUCN, Gland, Switzerland
Cambridge and Bonn. 134p.
Shyam Sundar, S. (1984). Forest development and Eucalyptus controversy in Karnataka,
Workshop on Eucalyptus plantation, Indian Statistical Institute, Bangalore.
Simberloff, K., Schmitz, K. C., and brown, T. C. (1997) Strangers in Paradise: Impact
and Management of Nonindigenous Species in Florida, Island Press, Washington,
D. C.
Sing, S. E. and Robert, K.D. P. (2003). A new perspective on invasive weed risk
assessment. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
the Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 82p.
Smart, M. (2003). An ecological approach to the problem of nonindigenous aquatic plant
invasions in reservoirs and waterways. Abstracts: Invasive Plants in Natural and
Managed Systems: Linking Science and Management in conjunction with the 7th
International Conference on the Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida, 83p.
Soerjani, M. (1970). Alang- alang Imperate cylindrica (L.) Beauv. Pattern of growth as
related to its problem of control. BIOTROP Bulletin No. 1. Regional Center for
Tropical Biology, Bogor, Indonesia.
Stanton, L.E., Irving, A. M., William, J. P., and Robert, G. D. (2003). The invasion
dynamics of a native grass, Phragmites australis, in a coastal brackish marsh
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology
170
and Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida. 85p.
Stocker, R. K. (2003). The control and management of invasive plants: How does a
manager succeed? Abstracts: Invasive Plants in Natural and Managed Systems:
Linking Science and Management in conjunction with the 7th International
Conference on the Ecology and Management of Alien Plant Invasions. November
3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 85p.
Stohlgren, T. J., Bull, K. A., Otsuki, Y., Villa, C. A., and Lee, M. (1998). Riparian zones
as havens for exotic plant species in the central grasslands. Plant Ecology, 113-
125.
Symstad, A. J. (2003). Lasting effects of Coronilla varia (crownvetch) invasion in sand
prairie. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
The Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 88p.
Tadesse, B. and Chala, I. (2003). Prosopis juliflora: Invasion, ecological and economic
impacts on pastoral community in the Afar Region, Ethiopia. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida, 88p.
Takhtajan, A. (1997). Diversity and Classification of Flowering Plants. Columbia
University Press, New York.24pp
Tanaka, H. (2004). The role of the international Plant Protection Convention in the
prevention and management of Invasive alien species. Program and Abstracts:
International Conference on Assessment and control of biological invasion risks.
August 26-29, 2004, Education & Cultural Hall, Yokohama National University
Tokiwadai, Hodogaya-ku, Yokohama, Japan. 45p.
Tanvir, A. (1996). Eucalyptus In Pakistan. In: White, K., Ball, J. and Kashio, M. (eds).
Proceesings of the regional expert consultation on Eucalyptus, 4- 8
october,1993.volume 1.FAO regional office for asia and the pacific,Bangkok.146p.
Thomas, K. A., John, A. H., and Steve, B. (2003). Cooperative weed management area
data management system in the Southwest. Abstracts: Invasive Plants in Natural
and Managed Systems: Linking Science and Management in conjunction with the
7th International Conference on The Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida 89p.
171
Thompson, K. (2000). The functional ecology of soil seed banks. In: M. Fenner, ed.,
Seeds: the ecology of regeneration in plant communities. 2nd ed., CABI Publishing,
London, 215-235 pp.
Thomson, D. M. (2003). Combining experiments and models to manage invasive plant
impacts: The case of a California endemic. Abstracts: Invasive Plants in Natural
and Managed Systems: Linking Science and Management in conjunction with the
7th International Conference on The Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 89p.
Thorne, R.F. (1992). Classification and geography of flowering plants. Botanical Review
58: 225-348.
Uddin, M. Z. and Mohammad, A. H. (2003). Invasive plant species of Bangladesh: A case
study on its impacts. Abstracts: Invasive Plants in Natural and Managed Systems:
Linking Science and Management in conjunction with the 7th International
Conference on The Ecology and Management of Alien Plant Invasions. November
3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 91p.
Ultsch, G.R. (1973). The effects of water hyacinth (Eichhornia crassipes) on the
microenvironment of aquatic communities. Archiv fuer Hydrobiologie, 72: 460-
473.
UNEP (2002) Decisions Adopted by the Conference of the Parties to the Convention on
Biologica Diversity at its sixth meeting, UNEP /CBD/COP /6/20. 45p
Ustin, S. L., Karen, S. O., Emma, U., Carlos, M. R., Deanne, D., and Lin, L. (2003).
Mapping invasive species using imaging spectrometry. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on the Ecology and Management
of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft.
Lauderdale, Florida 91p.
Van Riper, L. C. and Jennifer, L. L. (2003). The impact of yellow sweetclover (Melilotus
officinalis) on nitrogen cycling and native plant communities. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida 91p.
Vila , M. and Jordina, B. (2003). Atmospheric invasions of non-native pollen in a
Mediterranean region. Abstracts: Invasive Plants in Natural and Managed Systems:
Linking Science and Management in conjunction with the 7th International
Conference on The Ecology and Management of Alien Plant Invasions. November
3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 92p.
Vitousek, P. M., Antonio, C. M. D., Loope, L. L. and Westbrooks, R. (1996). Biological
invasions as global environmental change. American Scientist, 84: 468-478.
172
Vollmer, J. G. and Jennifer, L. V. (2003). Revegetation of annual brome (Bromus spp.)
infested rangeland. Abstracts: Invasive Plants in Natural and Managed Systems:
Linking Science and Management in conjunction with the 7th International
Conference on the Ecology and Management of Alien Plant Invasions. November
3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 93p.
Wang, R. and Meijuan, M. Z. (2003). The strategy study of accessing and managing exotic
plant species. Abstracts: Invasive Plants in Natural and Managed Systems: Linking
Science and Management in conjunction with the 7th International Conference on
The Ecology and Management of Alien Plant Invasions. November 3-7, 2003
Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 94p.
Washitani, I (2001) Restoring Ecosystems. NHK Publishing, Tokyo, Japan.76p
Washitani, I. (2000). Management of invasive naturalized plants. Japanese Journal of
conservation ecology, 5:181-185.
Washitani, I. (2002a) Introduced grasses for revegetation. In: Ecological Society of Japan.
Handbook of Alien Species in Japan, Chijinshokan, Tokyo, 207p.
Washitani, I. (2004). Invasive Alien Species Problem in Japan: an Introductory Ecological
Essay. Global Environmental Research, 8(1): 11-13
Weber, E. (2003). Invasive plant species: Global patterns of economic uses, origins and
geographic distributions. Abstracts: Invasive Plants in Natural and Managed
Systems: Linking Science and Management in conjunction with the 7th
International Conference on The Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida, 95p.
Weber, E. and Nicole, M. (2003). Differences in growth pattern and plasticity between
invasive and non-invasive goldenrods (Solidago) in Europe. Abstracts: Invasive
Plants in Natural and Managed Systems: Linking Science and Management in
conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham
Bonaventure Resort, Ft. Lauderdale, Florida, 95p.
Weber, E. and Peter, P. (2003). Alien floras of Europe and other continents – taxonomic
and geographic differences. Abstracts: Invasive Plants in Natural and Managed
Systems: Linking Science and Management in conjunction with the 7th
International Conference on The Ecology and Management of Alien Plant
Invasions. November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale,
Florida. 95p.
Weed Science Society of America (WSSA) (1948). Composite list of weeds. Weed
Science, 32 (2): 1-137.
Weiher, E. (2004). Community assembly rule and the prediction of invasion. Program and
Abstracts: International Conference on Assessment and control of biological
173
invasion risks. August 26-29, 2004, Education & Cultural Hall, Yokohama
National University Tokiwadai, Hodogaya-ku, Yokohama, Japan. 34p.
Whitham, T.G., Martinsen, G.D., Floate, K.D., Dungey, H.S., Potts, B.M., Keim, P.
(1999). Plant hybrid zones affect biodiversity: tools for a genetic-based
understanding of community structure. Ecology, 80(2): 416-428.
Williams, C.E., (1997). Potential valuable ecological functions of nonindiginous plants.
In: Luken, J.O., Thieret, J.W., (Eds.), Assessment and Management of Plant
Invasions, Springer, New York, 26-34 pp.
Williamson, M. H. and A. Fitter. (1996). The characters of successful invaders. Biological
Conservation, 78:163-170.
Wilson, S. (2003). Designing invasion-resistant grassland restorations. Abstracts: Invasive Plants
in Natural and Managed Systems: Linking Science and Management in conjunction with
the 7th International Conference on the Ecology and Management of Alien Plant Invasions.
November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida 96p.
Yan, X. (2003). ALIENS. Invasive Species Specialist Group (ISSG) of the IUCN species survival
commission.17:17-18.
Yoshida, K. and Shuichi, O. (2003). Invasion of Leucaena leucocephala and its impact on the
native plant community in the Ogasawara (Bonin) Islands. Abstracts: Invasive Plants in
Natural and Managed Systems: Linking Science and Management in conjunction with the
7th International Conference on the Ecology and Management of Alien Plant Invasions.
November 3-7, 2003 Wyndham Bonaventure Resort, Ft. Lauderdale, Florida, 98p.
Zabala, N. Q. (1990). Silviculture of Species. Field Document No. 14, UNDP/ FAO
(BGD/85/011). Pp. 113-122.
Zashimuddin, M., Latif, M. A., Khan, S. A. and Davidson, J. (1983). Performance of different
provenances of Acacia mangium in Bangladesh. Bano Biggyan Patrika, 12 (1&2): 57-61.
Zeiger, C.F. (1962). Hyacinth- obstruction to navigation. Hyacinth Control Journal 1:16-17.
Zhang, R. (2004) Introduction of invasive insects in China. In Abstracts: International Conference
on Assessment and control of biological invasion risks. August 26-29, 2004 Education &
Cultural Hall, Yokohama National University Tokiwadai, Hodogaya-ku, Yokohama,
Japan. 27p.
Zong, M. M. and Renging, W. (2003). The state of main exotic species in the north of China.
Abstracts: Invasive Plants in Natural and Managed Systems: Linking Science and
Management in conjunction with the 7th International Conference on The Ecology and
Management of Alien Plant Invasions. November 3-7, 2003 Wyndham Bonaventure
Resort, Ft. Lauderdale, Florida, 98p.
174
Web sites
http://www.weeds.crc.org.au/crc for australian weed management
www.gisp.org/Protecting plants and plant hanbitats from invasive alien species
http://www.mdinvasivesp.org/invasive species of concern in maryland
http://edis.ifas.ufl.edu./Natural area weeds:air potato
http://esa.sdsc.edu(Fact sheet-Invasive species. Invasion!)
file: factsheet-invasive species.htm
(www.cal-ipc.org/don’t plant a pest!)
www.ucsusa.org/call to action on invasive species
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Author’s Biography
Mohammad Redowan was born on 27th Dec
1977 and brought up at Habigonj district in
Bangladesh. He obtained Bachelor of
Science degree with honours in 2004 and
Master of Science degree in 2005 in Forestry
from the Institute of Forestry and
Environmental Sciences in Chittagong
University (IFESCU), Bangladesh. On
March 2005 he joined as a lecturer in the
Department of Forestry and Environmental
Sciences (DFES) in the Shahjalal University of Science and Technology (SUST), the
largest public university of its kind in Bangladesh. Currently he is working as an Assistant
Professor. In 2008, Mr. Redowan received the European Union Erasmus Mundus
scholarship for the MSc in ‘Geo-information Science and Earth Observation for
Environmental Modelling and Management (GEM)’ a course jointly organized by a
consortium of four partner universities of four European countries. His teaching and
research points of interest include application of remote sensing and GIS in forestry,
research methods, forest and environmental modelling.
Contact
Home address:
Mohammad Redowan
C/O Mohammad Sirajul Islam
Holding No 72/73
Shayestanagar Traffic Point (east side)
Habigonj-3300
Bangladesh.
Professional address:
Mohammad Redowan
Department of Forestry and Environmental
Science
Shahjalal University of Science and
Technology (SUST)
Sylhet-3114, Bangladesh
Tel: PABX.0821-713491, 713850/ extn.-273
Fax: 88-0821-715257
Email: [email protected]
Cell: +880-1818465634
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