Post on 19-Jun-2015
Invasive species: boon or bane
Submitted by:-
ManishaClass:- M.sc.(P) BotanyRoll no. 22
Contents Introduction Characteristics of invasive species Invasion Rule Process of Invasion Pathways of introduction
Deliberate Accidental
Impacts of invasive species Examples Controlling measures Conclusion References
Introduction Native species:- occurring within
their natural range.Non-native species:- Introduced
from somewhere else into new area.Invasive species:- Also called Non-natives, Introduced
sp. , Non-indigenous, Exotic sp. , Alien sp. , Foreign sp.etc.
Non-native organisms that cause, or have the potential to cause, harm to the environment, economies, or human health.
Characteristics of invasive species Fitness homeostasis Wide geographic range Highly successful seed dispersal, germination
and colonization Alternative mode of reproduction Strong competitors Allelopathic properties Have few natural predators, competitors,
parasites & diseases. High cost of removal and control Difficult to control or eliminate once established
Invasion rulestatistical rule says that 1 in 10 of imported species become
introduced1 in 10 of those introduced become
established1 in 10 of those established becomes a
pestAll these stages have probability of
≈10%→10’s rule (Williamson & Filter,
1996)
Steps involved in Invasion
.Transport Introduction
Establishment Spread
Impact
Ecological, Economic, Human Health
Pathways of introductionDeliberately introduced
(Intentional/Purposeful introduction
it refers to the movement of organisms to a new area for an express purpose i.e some benefit is expected .
Accidentally introduced (Unintentional introduction)species that are transported as a
byproduct of movement of other goods.
Intentional transport
For FoodGame speciesBio-controlOrnamental
plantsEnvironmental
enhancementConservation &
Scientific persuitesMany nurseries &
hobbyists
Unintentional transportAs hitchhikers.In containers,
packing material, baggage, travelers.
Attached to fishing gear, anchors, lines.
Non-Food Animal Pathways (aquarium trade, pets, non-food livestock, aquaculture, labs)
Attached to ship hulls.
Underwater view of a highlyfouled ship hull showing attached fouling organisms
Movement of species within ship ballast
Ocean going vessels must balance their cargo load to stabilize the ship.
Species carried in ballast include insects, plants, earthworms & many more organisms.
Impacts of invasive species
Some of them are:-Invasive species can alter entire
ecosystem.Displace native species.Reduce forest health & productivity.Compete with & replace rare and
endangered species .Hybridize with native plant species, altering
their genetic makeup & reduce gene pool.Reduce the amount of space, water,
sunlight and nutrients that would be available to native species .
ExamplesRed Water Fern, Azolla Water Hyacinth
Eichhornia crassipes Native of Asia Invaded African rivers
& lakes. Can double its
biomass every 2-3 days.
Carpet the surface of water bodies with mats.
Mats harbour mosquitoes & snails.
Brought from South America.
Double its biomass in 12 days.
Water covering plant.
Deprives bottom water of light & oxygen
Spotted knapweed(Centaurea maculosa)
A perennial composite(Asteraceae)
Native of EurasiaIntroduced in
North America in early 1900s accidentally as seed contaminant within crop seed imports.
it produces an allelo chemical.
Knapweed infestation
.Japanese Stiltgrass(Microstegium vimineum)
Garlic MustardAlliaria petiolata
Found in Crawford country.
Create ‘lawns’ in forests.
Displace native herbaceous plants.
Reduce biodiversity.
outcompetes native plants by monopolizing light, moisture, nutrients, soil and space.
It is allelopathic.
American ChestnutLargest trees of
Eastern Deciduous forest.
A Chestnut-Blight Fungus named (Cryphonectria parasitica) killed them.
It was introduced on logs in 1909.
By 1960n, Chestnut had been rendered functionally extinct.
Tree of Heaven(Ailanthus altissima)
Native to China.Invasive
throughout the U.S.A.
Allelochemical properties.
Common in urban areas(cause damage to sewers & structures).
Threat to cultivated fields.
Some invasive alien plants of India
Controlling MeasuresVarious methods
involving- Administrative
methods Mechanical
methods Chemical methods Biological methods Also involve strategies-
- alert local people- give priority to eradication of IAS.- conduct more research.- implement policies concerning invasive species.
ConclusionAlthough, Intentionally introduced
plants have priority over native species w.r.t. the household economy and national economy.
Invasive species threatens to native species, habitats and ecosystem functions and is economically costly.
So, invasive species can be both boon or bane to society. The relative magnitude of losses & benefits vary both in space and over time.
References1. Ambasht, R.S., and Ambasht, N.K.2008. A
Textbook of Plant Ecology, CBS Publishers & Distributers Pvt. Ltd., New Delhi.
2. Lerner, Brenda W. and Lerner, K.L. Environmental Science-In Context(Vol.1). Bejing, China.
3. Lockwood, L. Julie, Hoopes, F. Martha and Marchetti, P. Michael(2007). Invasion Ecology, 1st Edition. Blackwell Publishing Ltd. U.K.
4. Singh, J.S, Singh, S.P. and Gupta, S.R. (2010). Ecology, Environment and Resource Conservation, 2nd Edition. Anamaya Publishers, New Delhi.
Weblinkswww.nepjol.info/index.php/HJS/article/download/2
13/811www.nature.org/ourinitiatives/regions/...dc/.../md
invasivebrochurewww.arvindguptatoys.com/arvindgupta/
invasiveplants-1researchrepository.murdoch.edu.au/4635/1/
deliberate_introductions.related:www.orange.k12.oh.us/teachers/ohs/
jsangdahl/APESWEB/invasive%20species%20project2_files/invasive%20species%20project2.ppt invasive species ppt
www.awcf1911.org/ONeill%20IS%20Impact%20Oneida%20Lake%2007.ppt invasive species ppt
Thank you
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