Spatial and temporal variation of seed predation and removal of sympatric large-seeded species in relation to innate seed traits in a subtropical forest, Southwest China

摘要

Based on the complex seed packaging strategies involving morphology, nutrition quality and secondary chemistry, spatial and temporal variation of seed predation and removal by granivorous rodents was examined among six sympatric large-seeded tree species with different seed traits: Lithocarpus harlandii, Quercus variabilis, Q. serrata, Cyclobalanopsis glauca and Castanopsis fargesii (Fagaceae); Camellia oleifera (Theaceae) across different stands and seasons in a subtropical evergreen broadleaved forest, Southwest China. The smallest seeds of Castanopsis fargesii with lower tannin concentration, L. harlandii with the largest seed size and Camellia oleifera with high fat concentration, were harvested more quickly than the apparently less preferred seeds of Q. variabilis, Q. serrata and C. glauca with higher tannin concentration. Larger (L. harlandii and Q. variabilis) or high fat seeds (Camellia oleifera) have higher levels of removal and lower levels of instant consumption than smaller seeds (Castanopsis fargesii, Q. serrata and C. glauca) for both stand and season. Results showed that high fat or large seeds are harvested more quickly than small or medium seeds with high tannin concentration, and that high fat or large seeds are also more likelyto be removed than small or medium seeds with high tannin concentration. Moreover, seed predation and removal are consistent among stands and seasons. Innate seed traits are shown to be important in determining whether a given seed is eaten or removed when rodents are provided uniform number of seeds with differing traits. The hierarchical preference for larger or high fat seeds is maintained when background seed abundance varies in time and space.