Biotic congruence in humid tropical forests: a multi-taxa examination of spatial distribution and responses to forest disturbance

Abstract

Biodiversity is vital for fully functional natural habitats, and the maintenance of biodiversity through effective conservation planning depends on reliable information on its spatial distribution and response to anthropogenic disturbance. However, gathering extensive data on multiple species is a difficult task, due to logistical and financial constraints and the lack of taxonomic expertise. A common resource to address this hurdle is the use of surrogate taxa: focusing on a limited set of species that provide information that can be extrapolated to wider patterns of biodiversity and ecological integrity. We examine this by (1) testing if species richness proportions among different taxa/methodology employed (ants, birds sampled with point counts, birds sampled with mist nets, dung beetles, trees and saplings) will be similar across different undisturbed Amazonian forests, and (2) if patterns of local congruence in richness and community composition are consistent in undisturbed forest and gradients of forest disturbed by forest fires. Our results indicate that species richness, across field sites, was positively associated at a regional scale. At a local scale, richness and community composition in unburned forest showed virtually no correlation between the taxa, but the inclusion of samples from burned forest increased the number of significant correlations. Vegetation (trees ≥10 cm diameter at breast height) composition was the best indicator of overall community composition of all other taxa. The congruence of regional patterns of richness is likely a consequence of macro variables such as climate and biogeographical history, and should not be extrapolated to local scales. Although the use of community composition metrics increased congruence at a local scale, we highlight the importance of using a broad ecological gradient.