Trait-Mediated Seed Predation and Dispersal Are Regulated by Seed Abundance for Sympatric Tree Species in the Qinling Mountains, China.

Seed traits and seed abundance both affect rodent-mediated seed predation and dispersal. However, many previous studies have investigated these two factors independently; few have explored whether the effects of seed traits on rodent-mediated seed predation and dispersal vary with background seed abundance and across seasons. Here we investigated three sympatric Fagaceae species (Quercus variabilis, Quercus aliena, and Quercus glandulifera) with contrasting seed traits to determine how seed traits, seed abundance and seasonality shaped rodent-mediated seed dispersal and predation in the Qinling Mountains, China. Analysis of data from autumn 2016-2021 and spring 2022-2024 revealed clear rodent preferences among co-occurring seed species with contrasting traits. Q. variabilis seeds were harvested more rapidly and cached more frequently than those of Q. aliena and Q. glandulifera regardless of seed abundance or seasonal variation, whereas Q. glandulifera seeds were harvested most slowly, consumed most frequently, particularly in situ, and rarely cached. These patterns suggested that seed trait-mediated seed selection by rodents may play an important role in shaping masting effects on rodent-mediated seed predation and dispersal. We found that seed abundance also affected seed fates: lower seed abundance was associated with faster seed harvesting, whereas higher seed abundance was associated with greater seed consumption and lower seed caching. These patterns supported both the predator satiation and predator dispersal hypotheses, indicating that the two mechanisms can operate concurrently. Seasonal variation also affected seed fates. Caching was significantly more frequent in autumn, whereas consumption dominated in spring, when few seeds were cached. Our findings provide broader insights into how seed traits, seed abundance and seasonality shape rodent-mediated seed predation and dispersal, while providing a practical basis for promoting the natural regeneration of Fagaceae broad-leaved forests, conserving oak germplasm, and guiding artificial tending and afforestation in the Qinling Mountains.