CAB International

East African Invasive Species

Project Details

Grantee Organization: CAB International
Grant Amount: $182,210
Contact: Arne Witt
Contact Email: a.witt 'atsign'
Funding Dates: 6/15/12 - 6/14/15


Cabi_logoEast Africa is home to important biodiversity resources, including the Eastern Arc Mountains and Coastal Forests, a Global Biodiversity Hotspot, which is home to 1,750 plant species found nowhere else in the world. This biodiversity is threatened by Invasive Alien Plants (IAP), which outcompete indigenous species, often resulting in serious changes to ecosystem structure and species composition. Prior to this project, little was known about the number of invasive plant species present in East Africa or their impact. There were no databases, identification guides, or distribution maps. Though these countries are signatories to the Convention on Biological Diversity (CBD) and International Plant Protection Convention, authorities lacked information and tools supporting identification and management of IAPs, and thus were unable to effectively safeguard biodiversity. With the aim of helping national authorities protect biodiversity by identifying and managing IAPs, this project sought to fill some of these knowledge gaps, and use a variety of communications technologies to provide authorities with the information necessary for effectively safeguarding biodiversity in the region.

Key Objectives and Activities

  1. Identify staff from National Plant Protection Organizations and conservation agencies in the region’s six countries: Ethiopia, Tanzania, Kenya, Rwanda, and Uganda for mentoring, training, and capacity building in invasive plant management.
  2. Work with local staff to conduct rapid assessment surveys of roadsides to determine presence and distribution of invasive, and potentially invasive, plants in each country.
  3. Synthesize survey results into national invasive plant datasets, to be maintained by local infrastructure.
  4. Integrate East African national datasets into the CABI Invasive Species Compendium (ISC), a global online resource on invasive species.
  5. Produce and distribute (online) maps of known and potential invasive plants on East Africa online.
  6. Produce identification toolkit for IAPs in East Africa, focusing on 120 of the most problematic species.
  7. Accompany launches of national datasets and toolkit with awareness-raising campaigns.
  8. Conduct training workshops on invasive plant identification and threat for local conservation and agricultural research organizations.

Planned Outputs

  • Rapid assessment field surveys to provide the most comprehensive baseline information to date for East African countries on the presence and distribution of IAPs.
  • Information resources for managers and researchers to study and devise management strategies for IAPs, including national datasets, maps, fact sheets, identification tools.
  • Field guide to invasive plants of East Africa to be made available online and in print.
  • Increased national technical capacity to identify IAPs, through workshops and field training.

Planned Outcomes

The extensive field surveys aimed to both identify and begin to fill gaps in existing knowledge of IAPs in the region and the threats they pose, setting the stage for effective national management strategies and conservation actions to protect East African biodiversity resources. Data on nascent invasions could be used to lobby for rapid response to urgent threats. The project took a regional approach with the goal of increasing regional cooperation among East African states for cross-border approaches to control and prevention, helping each meet their international obligations to the CBD and 2020 Aichi Biodiversity Targets.

Last Updated: August 9th, 2017

Project Results

By the conclusion of the grant period, the project had accomplished the majority of its goals. Unfortunately, Burundi remained inaccessible due to political instability during the entire project timeline, but rapid assessment roadside surveys covered approximately 50% of the grid cells of the other five countries (Tanzania: 49%, Ethiopia: 37%, Kenya: 65%, Rwanda: 83%, Uganda: 74%). This resulted in more than 80,000 data entries, with species occurrences recorded at 1/4 degree grid cell resolution. From this information, maps for 200 IAPs were produced for the field guide, which will have entries for the 185 most problematic invasive plant species in the region. The field guide will be available in print and as an eBook, with specifics on identification, distribution, control, and impacts. Distribution information has also been incorporated into the CABI Invasive Species Compendium. Workshops on IAPs were held in all five of the surveyed countries, and two data launches highlighted the availability of the baseline information.

Lessons Learned

The prevalence, distribution, and impacts of invasive species are increasing worldwide, as is the demand for information necessary for their management. The urgency of the need in East Africa was demonstrated by the near-immediate implementation of survey data. In Tanzania, for instance, surveys documented the rapidly spread of two invasive plants, Parthenium hysterophorus, and Chromolaena odorata, which led to the approval of the introduction of appropriate biocontrol agents. Rapid responses to emerging threats are the best way combat the ecosystem-changing effects of invasive species. In addition, researchers are now investigating whether some invasive plants could be facilitating populations of malaria-carrying mosquitos.

Infrastructure and political instability also pose challenges to efficient collection of field data, and it remains critical to address local attitudes about invasive plants if management is to be effective. Some invasive species are actively cultivated as living fence lines, so education and providing benign alternatives will be important strategies to effect durable change.

Related Publications

  • Shackleton, RT; Witt, ABR; Aool, W; Pratt, CF. 2017. Distribution of the invasive alien weed, Lantana camara, and its ecological and livelihood impacts in eastern Africa. African Journal of Range and Forage Science. 2017: 1-11. DOI: 10.2989/10220119.2017.1301551 (link)

  • Shackleton, RT; Witt, ABR; Nunda, W; Richardson, DM. 2017. Chromolaena odorata (Siam weed) in eastern Africa: Distribution and socio-ecological impacts. Biological Invasions. 19(4): 1285-1298 (link)
  • Shackleton, RT; Witt, ABR; Piroris, FM; Wan Wilgen, BW. 2017. Distribution and socio-ecological impacts of the invasive alien cactus Opuntia stricta in eastern Africa. Biological Invasions. DOI: 10.1007/s10530-017-1453-x (link)

  • Witt, ABR; Kiambi, S; Beale, T; Van Wilgen, BW. 2017. A preliminary assessment of the extent and potential impacts of alien plant invasions in the Serengeti-Mara ecosystem, East Africa. Koedoe. 59(1): 1-16 (link)
  • Witt, ABR; Luke, Q. 2017. Guide to the naturalized and invasive plants of eastern Africa. DOI:  10.1079/9781786392145.0000 (link)

Project Director Biography

Dr. Arne Witt has been working in the field of invasion biology for more 15 years, researching the biological control of invasive plants and the management of invasive plant species. Currently, Witt is the Coordinator for Invasive Species at CABI Africa based in Nairobi, Kenya and the International Project Coordinator for the GEF/UNEP project, “Removing Barriers to Invasive Plant Management in Africa” which is active in Ethiopia, Ghana, Uganda, and Zambia.

Notes from JRS

CABI’s century-long work on invasive species has contributed to biodiversity conservation through policy support, innovative information products, and research on biological control. CABI was a founding partner of the Global Invasive Species Program, working to conserve biodiversity and sustain human livelihoods by minimizing the spread and impact of IAS.  In order to understand the problem and design efforts for study or damage mitigation, the identification and mapping of alien plant species is essential. Arne Witt’s effort over the last several years to survey invasive plants of East Africa has been extraordinary and vastly changes what we know about what plants and where they are invasive.  We hope that the identification guides and analyses that are starting to emerge will be taken up by local agencies for control and education and by policy makers to design, implement and monitor policy.  No JRS grantee very has and probably ever will cover as much ground as Arne did in pursuit of data!

Subscribe to our mailing list

* indicates required
Which are your primary communications interest?