Effects of seed traits and seed production on the seed predation and dispersal behavior of rodents.

Abstract

To deeply understand the foraging behavioral strategies of the rodents in response to seeds of different sizes and tannin contents under different seed densities and its relationship with plant regeneration, field experiments were conducted to explore the effects of artificial seeds of different sizes (large and small) and tannin (T) contents (0%T, 2%T, 8%T, and 15%T) on seed predation and dispersal behavior of rodents during simulated non-mast and mast seeding year in Larix principis-rupprechtii plantation of Liupan Mountains in Ningxia. The results showed that seeds were consumed rapidly by rodents in non-mast seeding year but relatively slow in mast seeding year. No significant difference of in situ predation rate (ISPR) was observed between non-mast and mast seeding year. The predation rates of seeds after dispersal (PRAD) by rodents in non-mast year were significantly higher than those in mast year, while the hoarding rate of seed after dispersal (HRAD) of the former was significantly lower than the latter. Both seed predation distance after dispersal (PDAD) and hoarding distance after dispersal (HDAD) by rodents in non-mast year were substantially higher than those in mast year. In non-mast year, both PDAD and HDAD of large seeds were longer than those of small seeds. Significant difference of the former was observed between large and small seeds for all tannin content seeds, but significant difference of the latter between large and small seeds was detected only for seeds of 2% and 15% tannin. In mast year, significant difference of PDADs and HDADs between large and small seeds was found in all other seeds of tannin contents except for 0% Tannin seeds. The ISPR maximized in medium tannin seeds and minimized in high tannin seeds. Maximums of PRAD were observed in high tannin seeds in non-mast year and 0% tannin seeds in mast year respectively. High tannin seeds had the highest HRAD while medium tannin seeds had the lowest HRAD in both mast and non-mast year. Our results suggested that mast seeding year could delay the seed consumption rate of rodents and increase the HRAD, but reduce the dispersal distance. Hoarding preference of the rodents on large seeds was demonstrated in both mast and non-mast years and the dispersal distance of large seeds was longer than those of small ones. It is probably that rodents prefer to predate in situ seeds of medium tannin and disperse high tannin seeds during both mast and non-mast years.