Current distribution of parthenium weed in Kenya and potential
impact on critical ecosystems Emily Wabuyele National Museums of
Kenya
Slide 2
Some facts on Kenya Located in the east-central part of the
African Continent, astride the equator About 7000 species of
plants, about 50 are IAS Agriculture contributes over 20% of GDP
Tourism contributes about 10% of GDP and is a top foreign exchange
earner Top invaders include prosopis, water hyacinth,
parthenium
Slide 3
Rationale for surveys Kenya: Status of knowledge Parthenium
first appeared in the mid 1970s Very little was known on actual
distribution and extent of invasion by 2009
Slide 4
Parthenium Project focus in Kenya To establish the actual
distribution and extent of invasion by parthenium weed in Kenya
Undertook roadside surveys to map occurrence of the weed in the
country Information collected on species associated with parthenium
(native and alien) Information on local knowledge of the weed
Slide 5
Data Collection: Site data sheet Locality Details (Geographical
coordinates & Altitude) Habitat type Details of invasion
Current Density (abundance) Morphological differences &
robustness Phenological data Date first seen Associated species
(Collect voucher material when possible) Local knowledge Local name
Is the species used locally (If yes, what is it used for) Is the
species harmful to livestock or humans?
Slide 6
Survey zones Target areas based on climex predictions and
herbarium records Major hi-way surveyed based on standard protocol
as used in Ethiopia and RSA Data collected in 2010 and 2011
Slide 7
Data Management Data points from surveyed areas entered into a
MS spreadsheet Mapping and spatial analysis of distribution
patterns in Arc View (based on Global GIS database)
Slide 8
Parthenium distribution: 2010, 2011
Slide 9
HABITATS INVADED
Slide 10
Invasions are not habitat specific Driven by wave of
disturbance
Slide 11
Indigenous Species associated with parthenium Species Abutilon
mauritianum Acacia drepanolobium Crotolaria labanifolia
Sphaeranthus ukambensis Ipomoea spp. Euphorbia hirta Plectranthus
hybridus Sida odorata Triumfetta flavascens Limited ethno
botanical/ economic impact information Lists of species associated
with parthenium are basis for ecological/biodiversity impact
studies)
Slide 12
Invasive Alien species associated with parthenium Amaranthus
spp. Opuntia ficus-indica Cassia siamea Cirsium vulgare Nicotiana
glauca Datura spp. Lantana camara Ricinus communis Sesbania sesban
Sida acuta Tagetes minuta Withania somnifera Xanthiun pungens
Significant inventory of IAS in Kenya, including voucher specimens
and IAS database initiated Basis for future management and/or
control program
Slide 13
Cumulative Data analysis/interpretation Parthenium hotspots
Corroborates Climex prediction: Western, S. Western Kenya, central
and Nairobi regions Coastal Kenya not yet invaded NOT INVADED
!
Slide 14
PATTERNS OF DISTRIBUTION: 1 ALTITUDE Lake Victoria Basin in
western Kenya relatively low Nairobi and Central Kenya quite high
above sea level Correlation with altitude not obvious
Slide 15
PATTERNS OF DISTRIBUTION 2: RAINFALL Very high rainfall
coincides with very high altitude Both Nairobi, Central and Western
Kenya receive relatively high rainfall Flooding rampant in the Lake
Victoria basin Isolated occurrences in semi arid localities (less
than 500mm) Correlation with relatively high rainfall evident.
Flooding seems to be ideal for dispersal
Slide 16
PATTERNS OF DISTRIBUTION: 3 SOIL TYPES Variable but mostly
clayey to loamy Some Correlation with type of soil evident
Slide 17
PATTERNS OF DISTRIBUTION 4: URBANISATION and associated
infrastructure development: In all survey areas, higher densities
of parthenium were found in towns and shopping centres Correlation
with urbanisation evident
Slide 18
Impact of parthenium dominance on Tourism Ecosystem stability
and wildlife diversity are core to tourism in Kenya Nairobi
National Park, Oldonyo Sabuk, Mara GR and L. Nakuru NP are already
invaded Partheniumn suppresses natural vegetation, replace dominant
flora in invaded habitats Has been reported to poison buffalo bull
calves in India reduced diversity of grazers and dependent
predators in ecosystems will drastically diminish visitor
numbers
Slide 19
Impact of Parthenium on agro-ecosystems Traditional bread
basket is in danger -Allelopathic inhibition reduces crop yields
-Increased weeding -Secondary host of crop pests educed seed set
due to heavy deposition of parthenium pollen Invaded crop field in
Western Kenya
Slide 20
Impact of parthenium on human Health Toxic to humans &
animals: dermatitis & respiratory allergies Human allergy
problems identified in Australia, Ethiopia and India 73% of people
living with weed in Australia are sensitive to it (women are twice
as sensitive) May lead to massive health risks to people who earn a
leaving as casual labourers due to intolerance to allergies
etc
Slide 21
Thoughts on status and future trends Weed has two distinct
epicenters. Central Kenya region is primary, western Kenya is
secondary Has spread from original points through movement of
people and vehicles Heavy rains and flooding increase danger of
invasion Outlier populations are considered to be founder
populations and evidence of future spread Costal Kenya is a
locality to watch due to increased construction of roads etc
Slide 22
Conclusions and recommendations Documentation accomplished in
this research is an important beginning for work on management Lack
of knowledge on potential impact of parthenium dangerously
predisposes Kenyan populace to social-economic risks Need to
consolidate knowledge of parthenium regionally/globally and embark
on tackling the next level of action:-management