Ant taxonomic and functional beta-diversity respond differently to changes in forest cover and spatial distance

Abstract

Habitat change affects both taxonomic and functional biodiversity, and beta-diversity is often used as a metric to describe these changes. Furthermore, spatially closer communities tend to have more similar species compositions (lower beta-diversity). These changes in community composition can be revealed with taxonomic and functional aspects of diversity. We assessed the responses of ant taxonomic and functional beta-diversity to changes in forest cover and spatial distance. We expected that changes in taxonomic and functional beta-diversity along a forest cover gradient would be caused by the replacement of open-habitat ant species by forest-habitat ant species. We sampled ants within twelve landscapes with different forest cover percentages in the southwestern Amazon of Brazil. Both taxonomic and functional beta-diversity of pairwise samples (βBC) were partitioned into their turnover (βBal) and nestedness (βGra) components. Increasing forest cover correlated with increases in taxonomic and functional βBC, however, βBal had a greater contribution to taxonomic βBC and βGra to functional βBC. Taxonomic βBC and βBal and functional βBal increased with spatial distance. Forest-habitat species richness increased, and open-habitat species richness decreased with increasing forest cover, while the richness of habitat-use generalist species did not vary. The loss of environmental heterogeneity may be responsible for generalist species dominance and open-habitat species presence in less-forested landscapes. This leads to great taxonomic replacement, but a nestedness gradient of function. Better land use planning is needed to ensure biodiversity and ecosystem functions of forest habitats in human-modified landscapes.