Research Article

Cross-boundary human impacts compromise the Serengeti-Mara ecosystem

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Science  29 Mar 2019:
Vol. 363, Issue 6434, pp. 1424-1428
DOI: 10.1126/science.aav0564

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Threats to the Serengeti

Protected areas are an important tool for conserving biodiversity and ecosystem functioning. But how well do these areas withstand pressure from human activity in surrounding landscapes? Veldhuis et al. studied long-term data from the Serengeti-Mara ecosystem in East Africa. Human activities at boundary regions cause animals to concentrate in the core of the protected area, which eventually reduces soil carbon storage and nitrogen fixation rates and increases vulnerability to extreme droughts. Similar patterns are likely for many, if not all, large protected areas.

Science, this issue p. 1424

Abstract

Protected areas provide major benefits for humans in the form of ecosystem services, but landscape degradation by human activity at their edges may compromise their ecological functioning. Using multiple lines of evidence from 40 years of research in the Serengeti-Mara ecosystem, we find that such edge degradation has effectively “squeezed” wildlife into the core protected area and has altered the ecosystem’s dynamics even within this 40,000-square-kilometer ecosystem. This spatial cascade reduced resilience in the core and was mediated by the movement of grazers, which reduced grass fuel and fires, weakened the capacity of soils to sequester nutrients and carbon, and decreased the responsiveness of primary production to rainfall. Similar effects in other protected ecosystems worldwide may require rethinking of natural resource management outside protected areas.

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