Effect of rodents on acorn dispersal and survival of the Liaodong oak (Quercus liaotungensis Koidz.)

We used a new method of labeling seeds with small pieces of coded tin-tags to investigate the effect of rodent on the seed fate of Liaodong oak (Quercus liaotungensis) in a mountainous area (40degrees00'N, 115degrees30'E) of Beijing, China. In the fall of 1999 and 2000, a total of 1994 and 660 acorns were released and then seed loss was checked. Both sides of the 50 m wide transect were extensively checked to locate the tagged seeds or their fragments. The results indicated that Apodemus speciosus, Rattus confucianus and A. agrarius were potential Liaodong oak acorn predators. Nearly all acorns were consumed by small rodents within 10 days after acorn placement, demonstrating that seed predation was very heavy and that rodent predation contributes to the poor seed regeneration of the oak. The dispersal distances of most seeds were within 20 m. The dispersal distance of the buried seeds was the longest and it was in favor of seed survival and seedling recruitment. Rodents preferred to eat tagged seeds under dense shrub. This is mostly related to predation risk in different micro-environments. Rodents tended to bury the tagged seeds under dense shrub. This burial place of rodent does not favor the seedling recruitment of the oak. The rodents preferred to move seeds to the horizontal and down directions of a slope and this tendency would save energy for rodents. The seeding regeneration rate of tagged acorns were very low in 2 years. Rodent predation is the causative factor of low regeneration of Liaodong oak in the study region. (C) 2002 Elsevier Science B.V. All rights reserved.