Differences of dispersal fitness of large and small acorns of Liaodong oak (Quercus liaotungensis) before and after seed caching by small rodents in a warm temperate forest, China

Though effect of seed size on seed fates has been widely studied, differences of dispersal fitness of large and small acorns before and after seed caching by small rodents is largely unknown. In this study, by tracking the seed fates of 2400 tin-tagged acorns (1200 large acorns with 3.2 +/- 0.6 g weight, and 1200 small acorns with 0.9 +/- 0.2 g weight) of Liaodong oak (Quercus liaotungensis) in three habitats, we compared the differences of seed consumption, removal, caching and survival between large and small acorns at four dispersal stages (at seed station, after removal, after caching and seedling recruitment) in a warm temperate forest in the Dongling Mountains, northwestern Beijing, China. This study was carried out during the period of October 2005 to May 2006. The results demonstrated that, (1) at seed stations where tagged seeds were released, large acorns had higher proportion of removal (and more quickly) and lower proportion of seed consumption by rodents than small ones; (2) after removal, large acorns were dispersed longer, and had higher proportion of seed caching than small acorns. But there was no difference in the proportions of seed consumption between large and small acorns; (3) after seed caching, large acorns had significantly lower proportions of survival than small acorns within the observed 30-days period, and the final survival proportions of initially released seeds by the next spring were very small for both large and small acorns and the difference was not significant; (4) large acorns had higher dispersal fitness before seed caching but lower dispersal fitness after seed caching than small acorns; there was no difference in total dispersal fitness between large and small acorns. In general, our findings suggest that large acorns of Q. liaotungensis have similar total dispersal fitness to small ones. (c) 2007 Elsevier B.V. All rights reserved.