Winner–loser Species Replacements Increase Rodent Diversity in Landscape Mosaics Exposed to Slash-and-burn Agriculture

Slash-and-burn agriculture creates heterogeneous landscapes composed of old-growth forests, secondary forests, and agricultural lands. In these mosaics, some species are extirpated (loser species) and replaced by disturbance-adapted species (winners). However, the community-level outcome of this winner–loser species replacement and its local and landscape drivers remain poorly understood. We assessed the effect of local land-use type and the surrounding old-growth forest cover on small rodent populations and communities in landscape mosaics exposed to slash-and-burn agriculture. We hypothesized that winner–loser species replacements may contribute to maintaining or increasing rodent diversity. Using Sherman traps, we sampled small rodents in 14 sites (5 old-growth forests, 5 secondary forests, and 4 agricultural lands) from the Mayan forest, Mexico. We then evaluated the effect of land-use type and landscape forest cover on species-specific abundance, total abundance, and species richness. We recorded 428 rodents from 6 native species and one exotic (Rattus rattus). Total abundance was weakly related to both predictors. Yet, one species (Ototylomys phyllotis) decreased in abundance in agricultural lands (loser species), and three species (Heteromys gaumeri, Peromyscus yucatanicus, and Sigmodon toltecus) followed the opposite pattern (winner species), which increased species richness in agricultural lands. The abundance of Heteromys gaumeri and Peromyscus leucopus also increased with old-growth forest loss, increasing species richness in more deforested landscapes. Our findings indicate that slash-and-burn agriculture promotes winner–loser species replacements, which maintain rodent abundance, but increase species richness. However, to prevent the extirpation of forest-dependent species, we must preserve old-growth forests.