Download Current distribution of parthenium weed in Kenya and

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 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?
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
HABITATS INVADED
 Invasions are not habitat
specific
 Driven by wave of
disturbance
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)
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
Cumulative Data
analysis/interpretation
Parthenium hotspots
Corroborates Climex
prediction: Western, S.
Western Kenya, central
and Nairobi regions
NOT INVADED!
Coastal Kenya not yet
invaded
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
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
PATTERNS OF
DISTRIBUTION: 3
SOIL TYPES
Variable but
mostly clayey to
loamy
Some
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 pests
educed 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 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
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