Current distribution of parthenium weed in Kenya and potential impact

on critical ecosystems

Emily Wabuyele

National Museums of Kenya

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

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

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

Data Collection: Site data sheetLocality Details (Geographical coordinates & Altitude)

Habitat type Details of invasion

Current Density (abundance)Morphological differences & robustness

Phenological data Date first seenAssociated species (Collect voucher material when possible)

Local knowledgeLocal name Is the species used locally (If yes, what is it used for) Is the species harmful to livestock or humans?

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

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)

Parthenium distribution: 2010, 2011

HABITATS INVADED

DUMP SITES

BUSHLAND

ABANDONED BUILDINGS ROADSIDE VEGETATION

DUMP SITES

HABITATS INVADEDCRO

P FIELDS

DRA

INAG

E AR

EAS

HO

MESTEAD

S

Invasions are not habitat specific

Driven by wave of disturbance

Indigenous Species associated with partheniumSpeciesAbutilon mauritianumAcacia drepanolobiumCrotolaria labanifoliaSphaeranthus ukambensisIpomoea spp. Euphorbia hirtaPlectranthus hybridusSida odorataTriumfetta flavascens

• Limited ethno botanical/ economic impact information

• Lists of species associated with parthenium are basis for ecological/biodiversity impact studies)

Invasive Alien species associated with partheniumAmaranthus spp. Opuntia ficus-indicaCassia siameaCirsium vulgareNicotiana glaucaDatura spp.Lantana camaraRicinus communisSesbania sesbanSida acutaTagetes minutaWithania somniferaXanthiun pungens

Significant inventory of IAS in Kenya, including voucher specimens and IAS database initiatedBasis for future management and/or control program

Cumulative Data analysis/interpretationParthenium hotspotsCorroborates Climex prediction: Western, S. Western Kenya, central and Nairobi regions

Coastal Kenya not yet invaded

NOT IN

VADED!

PATTERNS OF DISTRIBUTION: 1ALTITUDELake Victoria Basin in western Kenya relatively low

Nairobi and Central Kenya quite high above sea level

Correlation with altitude not obvious

PATTERNS OF DISTRIBUTION 2: RAINFALL

Very high rainfall coincides with very high altitudeBoth Nairobi, Central and Western Kenya receive relatively high rainfallFlooding rampant in the Lake Victoria basinIsolated occurrences in semi arid localities (less than 500mm)Correlation with relatively high rainfall evident. Flooding seems to be ideal for dispersal

PATTERNS OF DISTRIBUTION: 3

SOIL TYPESVariable but mostly clayey to loamySome Correlation with type of soil evident

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

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

Impact of Parthenium on agro-ecosystems

Traditional bread basket is in danger-Allelopathic inhibition reduces crop yields-Increased weeding-Secondary host of crop pestseduced seed set due to heavy deposition of parthenium pollen

Invaded crop field in Western Kenya

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

Thoughts on status and future trendsWeed has two distinct epicenters. Central Kenya region is primary, western Kenya is secondaryHas spread from original points through movement of people and vehiclesHeavy rains and flooding increase danger of invasionOutlier 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

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

Acknowledgements