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Improving lives by solving problems in agriculture and the environment
Staff image of Arne  Witt

Arne Witt Coordinator: Invasive Species South

T: +254 20 2271000


CABI, Canary Bird, 673 Limuru Road, Muthaiga, PO Box 633-00621, Nairobi, Kenya

For media enquiries and interview requests please contact or +44 1491 829395

I have been working in the field of invasion biology for the past 15 years. Within this time I have mainly concentrated on researching the biological control of invasive plants and the management of invasive plant species. I have travelled widely and have had the opportunity to observe plant invasions in Argentina, Brazil, Bolivia, Australia, and a host of African countries including Ghana, Madagascar, Zambia, South Africa, Uganda, Ethiopia and Mozambique among others.

I am currently the Coordinator for Invasive Species South, based in South Africa, 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. The project aims to strengthen policies and legislation on Invasive Alien Species (IAS); create awareness of the threats posed by IAS; build capacity to manage invasive species; and implement control strategies at selected sites in each of the four countries. I have considerable knowledge on invasive plants and their control and feel strongly that more needs to be done to manage them, especially in Africa, where they pose a massive threat to biodiversity, food security, economic development and human health.

Project image: Controlling Japanese knotweed in Great Britain

Researching introduced forest species in Trinidad

Many introduced species can have an adverse effect on native biodiversity, especially on a delicate island habitat such as Trinidad and Tobago. Three forest species are being particularly troubling, namely, Tectona grandis (teak), Acacia mangium (brown salwood) and Leucaena leucocephala (white leadtree). So,...
Project image: Controlling Japanese knotweed in Great Britain

Managing invasive species in selected forest ecosystems of South East Asia

Invasive species are threatening forest habitats in South East Asia. They also indirectly affect the livelihoods of millions of people who depend on forests for food, commodities and energy. CABI and the United Nations Environment Programme (UNEP), in collaboration with partners, have developed a project...
Project image: Controlling Japanese knotweed in Great Britain

Woody weeds in East Africa

Many exotic trees and shrubs have been introduced into Africa and become destructive invasive species. They're reducing native biodiversity and limiting the livelihoods of those that live in rural communities. CABI is trying to mitigate these impacts in East Africa by generating and sharing knowledge on...
Project image: Controlling Japanese knotweed in Great Britain

Controlling pest pear in Laikipia

Pastoralists in northern Kenya are heavily dependent on livestock. Their lives are being devastated by the non-native cactus Opuntia stricta. This weed has invaded the last good grazing land and when livestock and wildlife eat its fruits the spines can cause infection and death. Chemical and mechanical...
Project image: Controlling Japanese knotweed in Great Britain

Toolkits for invasive plants in Laikipia, Kenya

Many exotic plant species introduced to Laikipia County, Kenya, have escaped cultivation and threaten biodiversity. Little is currently known however, about the presence of invasive species or their impact. Without this type of information, it is unlikely that various stakeholders will take action to...
Project image: Controlling Japanese knotweed in Great Britain

Measuring the livelihood impacts of invasive alien species in East Africa

Although a lot is known about the biodiversity impacts of introduced species in East and southern Africa, very little is known about the livelihood impacts that they have on communities that depend on the goods and services provided by ecosystems. The aim of this project is to determine the negative...
Project image: Controlling Japanese knotweed in Great Britain

Toolkits for invasive plants in East Africa

Many plants introduced to East Africa have escaped cultivation and are wreaking havoc. These invasive species are reducing biodiversity and negatively impacting livelihoods. Little is known about the number of invasive plant species present here, or their impact. This project aims to use communication...