Delayed responses of small-mammal assemblages subject to afforestation-induced grassland fragmentation

Twelve Afromontane grassland fragments and 12 control sites were created in a pine-afforested region at Groenvaly in South Africa. Three live-trapping surveys of small mammals were performed, I survey a year before planting, I immediately after planting, and one 4 years later, yielding 768 small mammals representing 8 species. In 1998, small-mammal assemblages inside the plantations were also monitored. Between 1994 and 1998, similar changes in assemblage structure occurred in control sites and experimental fragments. In small fragments, Crocidura was comparatively abundant, apparently attributable to edge effects. Despite extensive habitat disturbance through afforestation by 1998, assemblage structure and movement distances within the plantation were similar to those recorded in undisturbed grassland assemblages. We conclude that, 4 years after afforestation, small mammals do not yet experience afforestation as a major habitat fragmenting force, and that gradual fragmentation at Groenvaly yields trends in small-mammal assemblages that are quite different from those of experiments employing abrupt habitat fragmentation.