Seed consumption and caching on seeds of three sympatric tree species by four sympatric rodent species in a subtropical forest, China

Because it is difficult and often impossible to distinguish dispersal, consumption and caching of seeds among different rodent species in the field, the differences of sympatric rodent species in affecting seed fates and forest regeneration are often unknown. To understand the different impact of four sympatric rodent species on seed fates of three sympatric tree species, we studied the food-hoarding behavior of Edward's long-tailed rats (Leopoldamys edwardsi), Chestnut rats (Niviventer fulvescens), Himalayan rats (Rattus nitidus) and Norway rats (R. norvegicus) on seeds of three sympatric tree species: Cork oak (Quercus variabilis), Serrate oak (Q. serrata) and Oil tea (Camellia oleifera) in a subtropical forest in the Dujiangyan Region, Sichuan Province, China. Consumption and caching of tagged seeds by rodents was measured in enclosures (10 m × 10 m) from September to December 2003. The results showed that Edward's long-tailed rats scatter-hoarded seeds of the three tree species. They scatter-hoarded Serrate oak significantly less than Cork oak (with large seed size) and Oil tea (with high energy). The transport distances of Serrate oak by all the four rodent species were significantly shorter than those of Cork oak and Oil tea. The cache sizes of the three seed species were all small. Most seeds were cached under grass or shrubs in the enclosure. In terms of the population abundance and food preference, Edward's long-tailed rats imposed most and the largest impact on seed fate of the three tree species. The results supported our hypothesis that sympatric rodent species may affect seed fate and forest regeneration differently. Only Edward's long-tailed rats might benefit the seed recruitment of Cork oak, Serrate oak and Oil tea, while the other three rodent species were purely seed-eater and thus might contribute little to seed regeneration of the three dominant tree species.