Effect Of Small Rodents Composition On Seed Dispersal And Seed Fates Of Tree Species In Xiaoxing'an Mountains

In order to study the dispersal processes of seed speceiss with different characteristics, we performed field and enclosure experiments in Dailing District, Yichun City, Heilongjiang Province in autumn of 2009 and 2010, in an attempt to explore the the effect of rodent composition on seed removal and seed dispersal. The test results are as follows:1. Our results indicated that Sciurus vulgaris, Apodemus peninsulae, Clethrionomys rufocanus and Tamias sibiricus were the main seed dispersers and predators.2. Small rodents showed different preferrence for or discrimination against seeds with different characteristics. Seed removal, dispersal and predation were highly correlated with small rodent composition in different habitats.3. When large-sized disperser S. vulgaris were absent, seed size and hull thickness played an important role in seed removal, and seeds with thick hull and large size were less likely to be removed. However, body size was more important than seed size and/or hull thickness in determining seed removal when S. vulgaris were present. Seeds with large size and thick hull were more likely to be removed and cached due to high ability of S. vulgaris to handle seeds. Large-sized seeds with thick hull tended to be dispersed at greater distance in the presence of S. vulgaris, while at shorter distance in the absence of this large-sized disperser.4. Our results illustrated that the effects of seed size and hull thickness on seed removal were manipulated by body size of rodents. Seed removal speed and dispersal distance can be affected by seed traits (e.g., seed size and hull thickness), however, body size appears to be the decisive factor influencing seed removal speed and dispersal distance when rodents with large body size and high manipulating ability appear. Body size is much more important than seed size and hull thickness in determining seed removal and dispersal, decline or disappearing of large-sized rodents will have negative influence on seed dispersal of tree species with large seeds.5. C. rufocanus act as pure seed-predator and larder-hoarder, which may reduce seed dispersal effectiveness. However, A. peninsulae and T. sibiricus scatter-hoard seeds of the five tree species, increasing dispersal effectiveness.6. Female chipmunks scatter-hoarded more seeds than males did; Inter-specific interference by Apodemus peninsulae significantly increased seed scatter-hoarding by chipmunks, while intra-specific interference showed no influence. Both intra- and inter-sexual interference showed no effect on scatter-hoarding of chipmunks; Male chipmunks scatter-hoarded more seeds when interfered by females, but did not change when interfered by males. Both inter-and intra-sexual competitions showed no significant influence on scatterhoarding of female individuals.