Impacts of scatter-hoarding rodents on restoration of oil tea Camellia oleifera in a fragmented forest

Few studies have evaluated the role of seed dispersal by animals (especially scatter-hoarding rodents) in natural restoration in fragmented forests. In order to assess the potential benefits of oil tea from natural dispersal by seedcaching rodents, we tracked the individual seeds with coded tin tags of oil tea Camellia oleifera (Theaceae), an economically important evergreen shrubs, by establishing artificial seed sources (mimicking natural seed rain) in a secondary stand (i.e. Camellia-poor stand, where no oil tea shrubs grow) in a fragmented forest in the Dujiangyan Region of Sichuan Province, China. Our results indicate that the total survival of the released seeds was zero, which confirms the hypothesis that poor seeding regeneration may be caused by poor seed sources and subsequent high rodent predation in fragmented secondary forests. As small rodents repeatedly handled the tagged seeds, the proportions of seed consumption (i.e. eaten) and removal were constant in both Dispersal I and Dispersal II, but the caching proportion significantly decreased and the missing proportion significantly increased. Our results also indicate that seed-caching rodents are important in promoting natural regeneration of oil tea through scatter-hoarding seeds in soil: (1) seed removal was high (91.2%); (2) many removed seeds were found to be cached (48.2% for the relocated seeds); (3) dispersal distances of the cached seeds ranged from 0 to 38 m (mean, 7.9 m); (4) 81.3% of the caches (including primary and secondary caches) contained only one seed. Therefore, seed-caching rodents could have the potential to help restore natural populations of oil tea if we increase oil tea seed sources in the Camellia-poor stands.