Prosopis juliflora management and grassland restoration in baringo county, Kenya: opportunities for soil carbon sequestration and local livelihoods.
Abstract
Climate change, land degradation and invasive alien species (IAS) threaten grassland ecosystems worldwide. IAS clearing and grassland restoration would help to reduce the negative effects of IAS, restore the original vegetation cover and sustain livelihoods while contributing to climate change mitigation, but uncertain financial benefits to local stakeholders hamper such efforts. This study assessed where and when net financial benefit could be realized from Prosopis juliflora management and subsequent grassland restoration by combining ecological, social and financial information. Impacts of Prosopis invasion and grassland degradation on soil organic carbon (SOC) in nine sublocations in Baringo County, Kenya, were evaluated. Then the financial impacts of Prosopis removal and grassland restoration in the area were calculated and spatially explicit management scenarios for each sublocation modelled, combining geographical information derived from satellite images taken in different years of the invasion with SOC data and socio-economic data collected in the sublocations. The expanding Prosopis distribution and density since 1995 have increased cumulated SOC storage on former bare land or degraded grasslands. On former pristine or restored grasslands, however, Prosopis invasion has reduced total SOC storage. Prosopis removal and grassland restoration are predicted to yield financial benefits through charcoal made from removed trees, increased cattle numbers and carbon credits. However, a trade-off between increased SOC and net financial benefit was found. The predicted net SOC increase would contribute around one-tenth, at most, to the net financial benefit. The available budget, based on Baringo households' average willingness to pay, would enable removal, on average, of one-fifth of Prosopis per sublocation in a single year. A larger area can be cleared if Prosopis is sparse than if it is dense. The analyses show that in some sublocations, households' annual investments could result in restoration of all former grassland areas. Synthesis and applications. This study shows how integrating and linking detailed ecological, social and financial geodata to develop accurate and realistic invasive alien species management scenarios can illustrate costs and benefits of management interventions in a spatial context. Such scenarios should be used more extensively to support land management decisions.