Habitat loss-biodiversity relationships are influenced by assembly processes and the spatial configuration of area loss

Abstract

Habitat loss greatly threatens biodiversity worldwide. However, how different facets of biodiversity (taxonomic, phylogenetic and functional diversity) decline with habitat loss is currently poorly understood. Habitat loss-biodiversity relationships, while important to understand in their own right, have the potential to reveal the underlying mechanisms that naturally structure plant communities and can further illuminate how spatial configurations of habitat loss affect biodiversity in a given amount of habitat. In this study, we used four spatial point process models to assess the relative importance of the processes of random placement of individuals, habitat filtering, dispersal limitation and the combined effects of habitat filtering and dispersal limitation in producing habitat loss-biodiversity relationships across different biodiversity facets for plant species in a subtropical forest. We assessed this using a 50 ha fully mapped subtropical forest in southern China by applying two simulated habitat destruction patterns, namely random and aggregated habitat removal to both real and simulated forest communities. We found that the combined effects of habitat filtering and dispersal limitation provided the best fit among the four competing assembly mechanisms, to the simulated habitat loss-biodiversity relationships applied to real forest data across all three biodiversity metrics. We also found that phylogenetic and functional diversity were less sensitive to the loss of habitat area than species richness and biodiversity declined more gradually under random habitat removal than for aggregated removal for both empirical forests and the simulated communities where assembly mechanisms generated intraspecific aggregation. Overall, our study examined how different assembly processes and the spatial configuration of habitat loss result in differing susceptibilities to diversity loss from habitat destruction and identified the potential mechanisms underlying the spatial patterns of diversity. This study also provides guidelines for the prioritization of the conservation of different facets of biodiversity under different spatial configurations of habitat loss.