Implications of Recent Research Findings for the Management of <i>Prosopis</i> Species in Eastern Africa

Abstract

This chapter provides a review of the key findings of recent research on the ecology and management of invasive Prosopis trees in eastern Africa and discusses their management implications. The Prosopis juliflora invasion is relatively young in eastern Africa, and large areas of suitable habitat remain uninvaded. This underscores the importance of prioritizing the prevention of further spread to areas suitable for invasion but that are currently uninvaded. Invasive Prosopis trees have substantial negative impacts on biodiversity, water resources, rangeland productivity and human and animal health, yet they do have some positive benefits. Handling this tension can be challenging, and management goals should be based on considerations of the net value (benefits minus adverse impacts) and not on single aspects or one-dimensional solutions. While management techniques are available and can be effectively applied at relatively small scales, this is not the case for invasions over larger areas where cost-efficient and sustainable options hardly exist. In addition, many stakeholders are involved, and they differ considerably in terms of their levels of awareness, how affected they are by the invasion, how empowered they are to deal with it and which outcomes they would prefer. This is a complex socio-ecological problem that demands transdisciplinary solutions codeveloped with communities and other actors at subnational and national scales. Effective solutions will have to be based on knowledge of (1) the ecosystem, (2) the target outcomes that would be both acceptable and possible, and (3) how the system can be transformed to achieve the desired outcomes. It is clear, though, that the use of biological control will probably offer the only way in which these invasions can be effectively and affordably managed. The utilization of biomass from the invading trees may bring some economic benefits but has demonstrably not been effective as a control method. Great care will therefore need to be taken to ensure that any programme of utilization does not interfere with the goal of bringing invasions under control.