Complex organism-environment feedbacks buffer species diversity against habitat fragmentation

8 October 2014

Zee, Peter; Fukami, Tadashi

Understanding factors that determine the extent of biodiversity loss following habitat destruction is central to ecosystem conservation and management. One potential factor is the ecological feedbacks between organisms and local environmental conditions, which can influence how species affect one another and, consequently, whether or not species persist in fragmented landscapes. We investigated this possibility using a spatially explicit individual-based model of plant communities. In this model, plant species affected their own and other species’ competitiveness by modifying local environmental conditions. These plant-environment feedbacks were assumed to vary among species pairs in direction and strength to mimic complex feedbacks observed between plants and soil conditions in real communities. We found that complex feedbacks reduced the extent of diversity loss, effectively buffering species against habitat fragmentation. Our analysis suggested that this buffering effect operated via two mechanisms. First, complex feedbacks decreased the likelihood of immediate extinction by making the spatial distribution of each species less clustered and consequently less likely to be eliminated entirely by fragmentation. Second, complex feedbacks decreased the likelihood of additional extinction by generating negative density dependence among surviving species, thereby keeping low-abundance species from going extinct due to demographic stochasticity and other forces. The buffering effect was particularly strong when species dispersed locally and abiotic environmental conditions varied globally. Our findings highlight the potential importance of organism-environment feedbacks in explaining the extent of species extinction by habitat destruction.