Invasive alien plants: a threat to the livelihoods of rural communities and biodiversity


In the 19th and 20th centuries, many woody alien plants were introduced in areas outside their native range. In countries of the global South, they were often introduced for reforestation or soil conservation purpose in degraded habitats; however, they represent an increasing threat to small farmers, pastoralists and the environment. In some areas of East Africa, the heavy infestation of those alien plants impair agriculture and livestock farming, driving farmers to migrate to the city. In South Africa alone, it has been estimated that the cost of woody invasive alien plant species could increase to $ 20 billion annually. Invasive alien plant species are also an increasing problem in Europe; for example, the economic impact of the allergenic common ragweed is estimated at several billion euros annually.


The aim of the project is to assess and quantify the expansion of woody weeds in Eastern Africa, and to understand and mitigate their negative impacts on the environment and on rural livelihoods by developing, testing, and disseminating adequate management practices. These management practices, which are designed and tested together with local implementation groups, include prevention and control measures, as well as early warning systems, which allow prioritizing effective planning measures.

Expected Benefits

The project will enhance environmental sustainability and livelihood security and thus help stabilizing social-ecological systems in semiarid areas of Eastern Africa. Thereby, it indirectly contributes to reducing rural depopulation in the affected areas. Such an integrative approach bringing together all major stakeholder groups and applying structured decision making processes for the selection of management strategies would also be suitable for tackling complex environmental problems in Switzerland.”

Contact Inormation

Urs Schaffner,

CABI Switzerland in collaboration with Centre for Development and Environment, University of Bern.

Invasive alien plants
Invasive alien plants

Target countries: Ethiopia, Kenya, and Tanzania

Research Partners:
In Switzerland: CABI Switzerland, CDE (University of Bern)
In Ethiopia: Water and Land Resources Centre, Haramaya University,
In Kenya: Kenya Forestry Research Institute (KEFRI), Centre for Training and Research in ASAL Development (CETRAD)
In Tanzania: Sokoine University of Agriculture, Tanzania Forest Research Institute (TAFORI)
In South Africa: Centre for Invasion Biology (CIB)

Cost: CHF 3 Mio

Duration: 6 years