Multi-spatial analysis on cave ecosystems to predict the diversity of subterranean invertebrates

Abstract

Subterranean habitats around the world can shelter diversified and threatened faunal communities. However, issues related to alterations in the landscape and structure of subterranean habitats still need to be better understood. Therefore, we used a multi-spatial scale analysis of land cover, land use, and cave habitats to predict the diversity of communities of subterranean invertebrates. We hypothesized that changes in land cover promote alterations in both faunal richness and composition and microhabitat diversity and that microhabitat features determined subterranean biodiversity. Sixteen limestone caves were sampled in Brazil at micro, meso, and macro scales using quadrats (1m²), transects (100 meters) as sample units inside caves and buffers with the radius of 100 and 250 meters in the surroundings of the cave entrances. Models performed showed that land cover and land use influenced cave environments, regarding both microhabitats traits and terrestrial invertebrate richness and composition. We also observed a relationship between microhabitat structure and terrestrial invertebrate richness and composition. Our results showed that deforested areas had negative effects on species richness and changed their composition, while natural areas had positive effects on microhabitat diversity. The same effects were observed for both 100 and 250 meters buffers. Invertebrate richness was negatively predicted by deforested areas while positively predicted by natural areas. Richness was also positively predicted by the combination of all microhabitat traits, and dissimilarity of fauna was influenced by microhabitat diversity in mesoscale and microscale by all microhabitat elements. The results highlight the importance of the landscape surrounding the caves to conserve the subterranean habitats and their fauna. Due to the spatial and temporal changes in the global environmental scenario, we argue the urgency of further detailed studies in fragmented landscapes to define minimum areas of protection for cave environments.