Patch and landscape effects on forest-dependent dung beetles are masked by matrix-tolerant dung beetles in a mountaintop rainforest archipelago

Abstract Naturally fragmented landscapesprovide suitable scenarios through which to investigate patchand landscapeeffects on biodiversity patterns in areas that are isolated from the disturbances usually associated with human-made fragments. We aimed to investigate the patchand landscapeeffects on the diversity of forest-dependent and matrix-tolerant dung beetlesin a naturally fragmented landscape. We also assessed the influence that seasonal and vegetation variations had on these dung beetles. We sampled dung beetlesduring two summers and two winters in 14 forest islands of various sizes and shapes within a natural mountainous forest archipelagoin southeast Brazil. We measured the patchand landscapevariables based on high-resolution multispectral imagesof circular sectorswith radii of 100, 250, and 500 m. We used dung beetlemetrics related to patchand landscapeattributes as part of generalized linear mixed models. The interaction between canopy cover and season influenced both species' richness and abundance of the dung beetle metacommunity. The forest-dependent species' richness increased with greater canopy cover, regardless of the season. Patchattributes (e.g., size, canopy cover, distance to the closest patch, and distance to continuous forest) and landscapeattributes (e.g., percentage of forest in the landscape, total edge, number of patches, distance to the nearest neighbor, and shape complexity) had small general effects on dung beetlespecies as a whole and on matrix-tolerant species in particular. However, these values strongly influenced forest-dependent species' richness, abundance, and temporal beta diversity. The matrix-tolerant species, therefore, mask the effects of patchand landscapeeffects on forest-dependent species within the mountainous forest archipelago. In other words, the changes in these patchand landscapeattributes influenced forest-dependent and matrix-tolerant species differently. Therefore, the evaluation of entire metacommunitiesmay not be helpful when evaluating species-specific responses in mixed landscapes—a fact that impairs the conservation of forest-dependent species.