Association between small rodents and forest patch and landscape structure in the fragmented Lacandona rainforest, Mexico

Identifying the main factors that shape biological communities in human-modified tropical landscapes has key ecological and conservation implications. In these emerging landscapes, the maintenance of biodiversity may depend on both forest patch and landscape attributes, but this topic has been poorly investigated. Here we assessed the landscape (forest cover, degree of fragmentation, and matrix composition) and patch metrics (tree basal area, patch size, and isolation) that best predicted the abundance and diversity of small terrestrial rodents in the Lacandona rainforest, Mexico. In 2011 and 2012, we sampled rodent communities in 12 sites (9 patches and 3 areas within a continuous forest). We assessed the landscape characteristics within a 100-ha buffer from the center of each site. In total, we captured 78 individuals in 2011 and 82 individuals in 2012 from four species: Desmarest's Spiny Pocket Mouse (Heteromys desmarestianus), Rice Rat (Oryzomys sp.), Mexican Deermouse (Peromyscus mexicanus), and Toltec Cotton Rat (Sigmodon toltecus). Only the abundance of rodents was strongly associated with forest patch and landscape attributes, but the best predictors differed between years. The degree of fragmentation, matrix composition, and patch isolation showed the lowest impact on rodents, probably because the region is dominated by a highly heterogeneous anthropogenic matrix. Community composition was weakly related to patch and landscape attributes in both years. Overall, our findings suggest that almost a half-century of land use in the region has not led to significant changes at the community level, but additional long-term studies including arboreal species are needed before a strong conclusion can be drawn.