Landscape composition is more important than landscape configuration for phyllostomid bat assemblages in a fragmented biodiversity hotspot

Abstract

Human-modified landscapes are composed of different types of land covers in differing proportions (landscape composition), and each with differing spatial physiognomy (landscape configuration). Unfortunately, the information on the relative impact of these two components of landscape structure on biological assemblages is scarce, but urgently needed to improve conservation strategies. We assessed the relative influence of the composition (landscape forest cover and matrix composition) and configuration (degree of forest fragmentation and forest edge density) of 100-ha and 500-ha landscapes on the abundance, diversity, and evenness of phyllostomid bat assemblages in the Lacandona rainforest, Mexico. We assessed the complete bat assemblage and frugivorous bats separately, and we grouped frugivores into understory foragers and canopy foragers. Landscape forest cover was the main predictor of the complete bat assemblage, positively affecting species diversity, particularly the number of rare species. Thus, community evenness decreased in landscapes with higher forest cover. Although weaker, species diversity was positively related to fragmentation and negatively associated with edge density. Landscape composition also was relatively more important than configuration for frugivores. The number of common and dominant frugivorous species and the abundance of understory frugivores increased in landscapes with lower forest cover and dominated by secondary forests in the matrix. The abundance of canopy frugivores showed the opposite response. Thus, to preserve bat assemblages and their important functional roles, conservation initiatives should prioritize a reduction in deforestation and the increase of secondary forests in the matrix. Maintaining all remaining forest patches is needed to favor landscape complementation and supplementation dynamics.