When a blessing becomes a curse…. A case of invasive Prosopis juliflora

Posted by Tshego Chilume @tschilume

When you live in an arid environment with temperatures that can go up as high as 47oC the prospect of the introduction of any tree into your area is music to your ears. This was the case for the people of Kgalagadi Desert when Prosopis juliflora and Prosopis grandulosa were introduced into the desert to control desertification and the constant moving sand dunes. For the first time large trees were seen around the district and communities had natural shade, fodder for their livestock and kids had playgrounds covered from the scorching sun. It was all merry; what could go wrong in such a beautiful scene? You would think nothing!


Except Prosopis is one of the worst invasive plant taxa in the world, it is capable of eradicating all woody plant species in its invaded habitat. Because there wasn’t much woody vegetation in Kgalagadi District, I figured there was no need to worry, however Kgalagadi Desert is known for its shrubs, cactus and grasses that have adapted to the harsh environment of their native ecosystem and are a valuable source of water and food for the locals, their livestock and wildlife. Forty years ago, the introduction was apparently met with dancing, celebrations and slaughtering of cattle (something Batswana do a lot when they have something to be happy about). But as time went on, a massive commotion has started between the relevant government agencies and communities. The impact of Prosopis is becoming increasingly apparent and difficult to ignore and everyone needs someone to blame for this. Prosopis is perceived to have caused the loss of native grasses, shrubs, reduction in borehole water yields, poisoning livestock and causing allergies to people. The communities blame the department of forestry for the introduction, forestry blames political pressure while the politicians blame the communities for insisting on a quick solution and the department of forestry for not doing enough research prior to the introduction.

The situation is that a solution to this social unease was necessary and back then there was very little funding available for research in issues of environmental issues. Even today, funding for research in environmental issues comes from donors outside Botswana. While this bickering continues, the impacts of Prosopis in Botswana have never been quantified and the current control practices were brought about by the public outcry.

This brings me to my current research on quantifying the ecological impacts of Prosopis juliflora in Gantsi District, the most ecologically and economically valuable district of Botswana. Gantsi district is home to one of the largest wildlife management areas in the world, Central Kalahari Game Reserve and in close proximity to the Okavango Delta (a world heritage site). This research will provide the impacts associated with Prosopis juliflora on the soil chemical variables and vegetation of Gantsi District. The research will improve our understanding of the effects of Prosopis and enable government to make informed decisions on the control measures and development of Prosopis management programmes.

tshegoTshegofatso Sputnik Chilume is an MSc student in the Centre of Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland. She is supervised by Cate Macinnis-Ng and Keotshepile Kashe (Okavango Research Institute, University of Botswana) quantifying the ecological impacts of Prosopis juliflora in Gantsi District, Botswana.

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