Herding strategies under shifting rainfall conditions: implications for rangeland conservation and pastoralist livelihoods

Abstract

Understanding rainfall variability is of great importance in East Africa, where small-scale farmers and pastoralists dominate. Factors such as fire, herbivory and soil conditions also determine the spatial and temporal plant productivity, influencing livestock production and wildlife sustainability. This study focused on assessing pastoralist herding strategies under varying rainfall conditions as well as their implications to rangeland conservation and pastoralist livelihood. I conducted 241 household interviews, collected information from 52 participants of Participatory Rural Appraisal (PRA), and used rainfall archived data from the Ngorongoro Conservation Area Authority (NCAA) to assess pastoralists’ perception and actual trends in rainfall, drought frequency, pasture availability, rangeland cover, and livestock production. I established four exclusion plots of 1 m2 each within an area of 50 x 100 m at eight sites to quantify the effect of grazing and to estimate grass productivity across season and elevation. Single and multi-species groups of wild herbivores were recorded along road transects in human-dominated landscapes of the Ngorongoro Conservation Area (NCA) in two sampling periods (wet season: November–May and; dry season: June–October) in 2018-2019. Most (71%) pastoralists were aware of general climate change, rainfall variability, and impacts of extreme events on their livestock. The exclusion plots showed that aboveground primary productivity and recovery from grazing was driven by both rainfall (F3, 4 = 19.165, p < 0.0001) and elevation (F2, 3 = 11.319, p = 0.023). Wild herbivore group sizes (Mean ± SE) were larger during the wet (7 ± 1 browsers, 19 ± 2 grazers and 19 ± 3 mixed feeders) than during the dry season (3 ± 0 browsers, 13 ± 1 grazers and 13 ± 4 mixed feeders) and varied seasonally with distance to Ngorongoro crater, streams, and human settlements. The study concludes that rainfall variability and recurrent droughts are the major challenges to livestock production in NCA. Moreover, increasing livestock population and high dependence on grazing resources impact the potential of the rangeland to support livestock and wildlife. The study recommends that wildlife coexistence is crucial for the protection status of this man-and-biosphere reserve, however, the management should determine the optimal resource ratio and the level of stocking densities the rangeland can support.