The adoption of a sustainable land management practice (SLM) to manage invasive Prosopis juliflora – considered one of the world’s most threatening non-native tree species – appears to have ‘uprooted’ the problem in East Africa.

A new CABI-led study involving colleagues from Sokoine University of Agriculture, Tanzania, the Tanzania Forestry Research Institute, and the University of Nairobi, Kenya, found uprooting and use of the cleared land for continuous crop and fodder production in two invaded regions of Kenya and Tanzania to be successful.

The research, published in the journal CABI Agriculture and Bioscience, assessed the reasons why people – as part of the CABI-led Woody Weeds Project – in Baringo, Kenya, and Kahe, Tanzania, adopted the SLM practice, or not, as well as if there was an effect of the project on the adoption.

The novelty of this study was that the scientists found that the SLM practice was adopted by people in the two regions who were not directly involved in the project activities.

75% of households implemented the SLM practice

The scientists found that about 75% of the 154 interviewed households in Baringo and 148 interviewed households in Kahe implemented the SLM practice while 76 did not and 10 no longer implemented the practice to control the spiny shrub or tree known as Prosopis juliflora.

They also discovered that the likelihood of people adopting was higher for male than female respondents and was positively related to farm size.

Prosopis juliflora was introduced from its native Latin America into Eastern Africa to reduce dust storms and provide wood and fodder for livestock but is has spread from the original areas of introduction and invaded large areas of land, thereby replacing grazing and arable land with impenetrable thickets.

Winnie Nunda, Research Officer, Invasive Species Management and an author of the study, said, “Our results show that all respondents prefer the SLM over a situation where their land is invaded by prosopis, even if the investment to uproot prosopis is high.”

Respondents preferred SLM over invaded land

Dr René Eschen, an author of the research and Research Scientist, Ecosystems Management, and Risk Analysis and Invasion Ecology at CABI, said, “This confirms that people prefer farming over prosopis, and their perception of the SLM became more positive over time. Altogether our results illustrate the beneficial effects of SLM practice, despite high initial investment and risk of injury while uprooting prosopis.”

Dr Charles Kilawe, of Sokoine University of Agriculture and a co-author of the research, added that the results further indicate the value of communal meetings for dissemination, as many people learn about new practices through observation of their neighbour’s activities and during public barazas.

Favourable benefit:cost ratio of the practice

Dr Kilawe said, “The ability to see the practice being implemented and discuss practical aspects and the favourable benefit:cost ratio of the practice with those who were involved in implementation, either land users or project staff, may have convinced other people of the benefits of crop production over prosopis.

“Given the positive opinion of people who have adopted the practice in the two regions, and that most interviewees prefer the practice over not managing prosopis, we propose upscaling of the practice to other areas infested by prosopis.

“Promoting the practice in new areas through implementation by stakeholders at demonstration sites as well as through community meetings may increase the rate of adoption.”

The scientists further stress that the result of their study highlights the need for further projects aiming at engaging residents of other regions, in East Africa and elsewhere in the world where prosopis is invasive, in sustainably managing prosopis infested lands.