Sympatric Fagaceae Segregate Rodent Scatter-Hoarding Services for Similar Seed Dispersal Effectiveness in a Subtropical Forest in China.

Abstract

In forest ecosystems where seed dispersal is predominantly mediated by scatter-hoarding rodents, sympatric plants compete for these limited dispersal services. This competition can drive niche differentiation, prompting the question of how ecologically similar species achieve coexistence. To address this, we conducted a seed provisioning experiment in the Ailao Mountains, Yunnan Province, China. We released 4500 tagged seeds from three congeneric species of stone oaks (Lithocarpus hancei, Lithocarpus xylocarpus, and Lithocarpus pachyphyllus; Fagaceae) to compare their seed dispersal effectiveness (SDE) and identify the divergent strategies that may facilitate their coexistence. Seeds of all three species were more likely to be removed than eaten in situ. Among the removed seeds, the proportion of cached versus eaten did not differ significantly among species. L. pachyphyllus exhibited both a higher seed removal rate and greater dispersal distances compared to L. xylocarpus and L. hancei. However, in contrast to its congeners, L. pachyphyllus seeds were more frequently dispersed to shrub microsites rather than open areas. Despite these contrasting dispersal patterns, the three species ultimately achieved statistically similar SDE. These results demonstrate that congeneric species can exploit rodent dispersal services in distinct ways while attaining equivalent dispersal effectiveness. This niche segregation in dispersal strategy represents a potential form of niche partitioning that could theoretically promote coexistence among ecologically similar species.