Most Namibian farmers regard the Prosopis as an alien invasive plant species.
But according to a recent study undertaken by 10 local experts, the revenue potential from harvesting 5 percent of Prosopis pods at the current density was calculated at N$7 million per annum in the Auob Basin and N$1 million in the Nossob Basin.
Prosopis glandulosa, also commonly known as the mesquite or honey locust, is a common and abundant tree in Namibia. It is a highly aggressive alien invasive species. The tree favours watercourses, disturbed soil around water points and farmsteads, roadsides and moist areas around natural fountains.
The conclusion of the study was that less than 1 percent of the potential income from Prosopis pods is being generated currently, and although Prosopis trees are detrimental to the environment, they have great economic potential, which is not being explored.
The Auob and Nossob basins were used for the study because they are among the most affected areas in the country. They form part of the Molopo-Nossob Basin, which is an internationally shared river basin between Namibia, Botswana, South Africa and Lesotho. The Prosopis is regarded as having the most adverse ecological impacts among alien plants in Namibia.
The study by A. Shekunyenge, C. Charline, E. Haimbili, A. Auala, H. Shipani, J. Ndjamba, M. Kabajani, N. Hembapu, T. Gottlieb and T. Shuuya analysed the environmental and socio-economic impacts of Prosopis in the two basins, specifically in Aranos, Bernafay, Gochas, Stampriet and Leonardville.
A variety of methods were used to collect the data on the biophysical and socio-economic aspects of Prosopis, ranging from belt and driving transects, digging of Prosopis, interviews with stakeholders, direct observations of growth patterns and literature reviews.
The study found that the control measures employed by stakeholders are dependent on how they view Prosopis and their economic status. The majority of commercial farmers prefer that Prosopis be eradicated, because it has a negative effect on their farming operations.
However, poor rural communities on the other hand say that they benefit from the Prosopis plant by collecting and selling it, or using the pods for fodder. Therefore, for them, there is no gain in eradicating the Prosopis.
The findings suggest that Prosopis is more abundant along drainage systems as a result of higher surface water availability. Out of 21 respondents, about 81 percent believe that Prosopis reduces groundwater and that it has slowed the flow of the rivers. The results also indicated that controlling the Prosopis could result in the re-establishment of local plant populations.
Despite its devastating invasive nature, this tree has an array of features that make it rather useful. It grows extremely rapidly, has very dense shade, produces a seed pod in great abundance that is eaten by animals and humans alike, while it is also readily available firewood.