Cascading effects of forested area and isolation on seed dispersal effectiveness of rodents on subtropical islands

1. Habitat loss and fragmentation often leads to defaunation of large-bodied mammals, and their loss could trigger release from top-down control or food resource competition for small mammal seed dispersers, which in turn may affect the effectiveness of seed dispersal by altering the number of dispersed seeds or the manner in which they are dispersed. Although rodents are primary seed dispersers in habitat subjected to defaunation, changes in seed dispersal effectiveness of rodents along mammalian defaunation gradients, and empirical support for mechanisms underlying alteration of this ecological process, are unclear.
2. We assessed the direct and indirect effects of forested area and isolation on seed dispersal effectiveness of rodents on 21 study islands with varying levels of defaunation in the Thousand Island Lake, China. We used camera sampling, live traps, and semi-quantitative acorn counts to assess occurrence of large-bodied mammal species, relative abundance of small rodent sp...