Large mammal diversity and their conservation in the human-dominated land-use mosaic of Sierra Leone

Abstract

Like elsewhere in West Africa, the landscapes of Sierra Leone are strongly human-dominated with consequences for large mammal distribution and diversity. Sierra Leone is currently going through a phase of post-war recovery, with accelerating development of the mining, forestry, agricultural and infrastructure sectors. As environmental issues are increasingly considered, comprehensive biodiversity information is required. Here we evaluate spatial patterns of large mammal diversity throughout Sierra Leone to make inferences about species persistence. We used systematic line transect sampling for assessing large mammal distribution. GLMs and canonical correspondence analyses were used to evaluate the relative importance of human impact for every species while controlling for environmental gradients and to make countrywide spatial model predictions. We further developed an algorithm to identify core distributional ranges for the most common species. A total of 562 km of transects were surveyed and 35 large mammal species encountered. Species diversity was impoverished in the country’s south and center and strongly increased towards the north and east. Human impact did not determine the distribution of four species (brushed-tailed porcupine, bushbuck, giant rat, warthog), but was very influential on chimpanzee and yellow-backed duiker occurrence with U-shaped and negative responses, respectively. The remaining species showed mixed responses to human impact and environmental gradients. Predicting species persistence in West African human-dominated landscapes is complex. Pooling of species for land-use planning is therefore not recommended. Our study provides key information for land-use planning to separate areas with post-depletion species assemblages from more diverse regions with high conservation value.