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Current distribution of parthenium weed in Kenya and potential impact on critical ecosystems Emily Wabuyele National Museums of Kenya.

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Presentation on theme: "Current distribution of parthenium weed in Kenya and potential impact on critical ecosystems Emily Wabuyele National Museums of Kenya."— Presentation transcript:

1 Current distribution of parthenium weed in Kenya and potential impact on critical ecosystems Emily Wabuyele National Museums of Kenya

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

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

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

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?

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

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)

8 Parthenium distribution: 2010, 2011


10  Invasions are not habitat specific Driven by wave of disturbance

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)

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

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 !

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

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

16 PATTERNS OF DISTRIBUTION: 3  SOIL TYPES Variable but mostly clayey to loamy Some Correlation with type of soil evident

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

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

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

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

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

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

23 Acknowledgements

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