Effects of mast seeding and insect infestation on predation and dispersal of Castanea mollissima nuts by rodents in the Qinling Mountains of China

Abstract

Seed predation and dispersal by rodents plays an important role in woodland regeneration. To understand the impact of insect-infestation under different food abundance conditions on rodent predation and dispersal preferences, it is necessary to determine whether rodents have the ability to distinguish between infested and non-infested seeds and whether feeding strategies are affected by food abundance. Here, we compared the predation and dispersal fates of infested and non-infested nuts of Castanea mollissima in mast and non-mast years in a subtropical forest in the Qinling Mountains, central China. We found that rodents could discriminate between infested and non-infested nuts of C. mollissima. Harvest rates of non-infested nuts were relatively faster than those of infested nuts, and rodents preferred to consume infested nuts (typically in situ), while non-infested nuts were cached more often and dispersed farther. Mast seeding had a significant effect on seed predation and dispersal by rodents. When per capita food availability was low (i.e., in non-mast years), harvest rates and dispersal distances (including eaten and cached distances) were obviously accelerated and increased irrespective of insect-infestation. While in mast seed years rodents chose to cache more nuts, and selectively caching a higher proportion of non-infested seeds. This indicated that mast seeding could promote seed caching and result in more seeds escaping predation, which would enhance seed germination and forest regeneration.