Anthropogenic stressors influence small mammal communities in tropical East African savanna at multiple spatial scales

Abstract

Context Protection of natural ecosystems undoubtedly safeguards ecological communities, with positive benefits for ecosystem processes and function. However, ecosystems are under threat from anthropogenic stressors that reduce the resilience both of component species and the system as a whole. Aims To determine how anthropogenic stressors (land use and climate change) could impact the diversity and resilience of a small mammal community in the greater Serengeti ecosystem, an East African savanna comprising Serengeti National Park (SNP) and adjacent agro-ecosystems, at local (SNP) and Africa-wide geographic scales. Methods We recorded small mammal species in 10 habitats in the greater Serengeti ecosystem, including the agro-ecosystem, over 48 years (1962-2010). We calculated richness and diversity for each habitat type, and used an index of similarity to quantify differences in the community among habitats. Species accumulation curves were also generated for each habitat type. Key results We recorded 40 species of small mammals in the greater Serengeti ecosystem. At the local scale, restricted habitat types in SNP (each <1% of the total area) made a disproportionately large contribution to diversity. Agro-ecosystems had lower richness and were less likely to contain specialist species. At regional and Africa-wide scales, local endemics were less likely to be recorded in the agro-ecosystem (57% species loss) compared with those with regional (33% loss) or Africa-wide (31%) geographic distributions. Conclusions At the local scale, the variety of habitats in SNP contributed to overall diversity. However, the ability to maintain this diversity in the adjacent agro-ecosystem was compromised for localised endemics compared with species with Africa-wide ranges. Land use intensification adjacent to SNP and projected changes in rainfall patterns for East Africa under global climate scenarios may compromise the future resilience of the small mammal community in this tropical savanna ecosystem. Implications The loss of rare or specialised species from protected areas and human-modified ecosystems could be mitigated by: (1) increasing habitat complexity and maintaining specialist habitats in the agro-ecosystem; and (2) creating buffers at the boundary of protected natural ecosystems that accommodate regime shifts in response to climatic change. These measures would increase the resilience of this coupled human-natural savanna ecosystem.