Habitat fragmentation is a leading threat to biodiversity worldwide, resulting in population isolation through the disruption of ecological processes such as seed dispersal. Corridors are a popular method for mitigating habitat fragmentation and are known to increase rates of seed dispersal, but little is known about their impacts on the seed rain of entire plant communities. We quantified the effects of corridors and habitat edges on seed rain in 6 experimentally fragmented landscapes at the Savannah River Site, SC. Each landscape consisted of a central patch surrounded by four peripheral patches; of these peripheral patches, one was connected by a corridor while the remaining three were unconnected and isolated by pine matrix. Patches were predominately open habitat, dominated by herbs and shrubs, while the matrix consisted of dense pine plantation forest with less diverse understory. We established seed traps in the two patch types (connected and unconnected) at patch edges, within patches, and in the surrounding matrix habitat. We collected seeds from traps on a monthly basis beginning in August 2007 and ending in January 2008.
Results/Conclusions Habitat fragmentation altered levels of seed rain through edge effects, but this effect was not mediated by corridors. Seed rain (number of seeds and species richness of seeds) was greatest in patch centers, declined slightly at distances intermediate between patch centers and edges, declined sharply at patch edges, and was lowest in the matrix. These results suggest that the abiotic environment near edges reduces seed rain, perhaps due to reduced plant productivity. Seed rain did not differ between connected and unconnected patches. However, seed rain in corridors was lower than in patches and comparable to levels at patch edges, suggesting corridors functioned similarly to edge habitat for the populations of plants within them. Our findings could have important implications for plant communities in fragmented landscapes where corridors are currently implemented. Increased knowledge of corridor ecology, edge effects, and the interactions mediated by these factors will allow us to more effectively inform conservation and restoration efforts for plant communities in isolated, patchy habitats.
