CORRIDORS CAUSE DIFFERENTIAL SEED PREDATION

Abstract

Corridors that connect disjunct populations are heavily debated in conservation, largely because the effects of corridors have rarely been evaluated by replicated, large‐scale studies. Using large‐scale experimental landscapes, we found that, in addition to documented positive effects, corridors also have negative impacts on bird‐dispersed plants by affecting seed predation, and that overall predation is a function of the seeds' primary consumer (rodents or arthropods). Both large‐seeded Prunus serotina and small‐seeded Rubus allegheniensis experienced greater predation in connected patches. However, P. serotina experienced significantly less seed predation compared to R. allegheniensis in unconnected patches, due to decreased impacts of rodent seed predators on this large‐seeded species. Viewed in light of previous evidence that corridors have beneficial impacts by increasing pollination and seed dispersal, this work demonstrates that corridors may have both positive and negative effects for the same plant species at different life stages. Moreover, these effects may differentially affect plant species within the same community: seeds primarily consumed by rodents suffer less predation in unconnected patches. By shifting the impact of rodent and arthropod seed predators, corridors constructed for plant conservation could lead to shifts in the seed bank.