Effects of different habitats and coverage treatments on the fates of Quercus wutaishanica seeds under the predation pressure of rodents
啮齿动物捕食压力下生境类型和覆盖处理对辽东栎种子命运的影响

Quercus wutaishanica is one of the dominant tree species in warm temperate deciduous forest of China. The predation and removal / burial of the seeds by rodents play an important role in the creation of seed shadow of the tree species. The present study examined the effects of community habitats and the treatments of litterfall removal, litterfall coverage and soil coverage on the predation and removal / burial of Q. wutaishanica seeds by rodents in both degraded Q. wutaishanica shrubs and secondary Q. wutaishanica forest ("shrubs site" and "secondary forest site" hereinafter) of Liupan Mountains, northern China. The results showed that the treatments of litterfall and soil coverage facilitated the seed survival in the early of release, while the finial survival rate of seeds in shrub site was significantly higher than that of secondary forest site after 40 days since release (Z=-2.333, P=0.020). The final survival rate of seeds in control plot was significantly higher than that of those covered by litterfall in shrub site (Z=-0.674,P=0.05), but no significant difference was observed between other treatments. In the secondary forest site, however, the seeds could neither finally survive under the coverage of litterfall, nor did the seeds under the treatment of litterfall removal. The survival rates of seeds in both control plot and with soil coverage were lower than 1%. There was no significant difference between the treatments. We observed a significant difference between the two community habitats in in situ predation rate (ISPR) of Q. wutaishanica seeds by rodents (Z=-2.333,P = 0.020). The highest ISPRs were achieved under litterfall coverage in shrubs site and soil coverage in secondary forest site (45.56% and 64.81% respectively). The treatment of litterfall removal resulted in the lowest ISPR (23.70% in shrubs site and 40.00% in secondary forest site respectively). Both habitat types and coverage treatments did not significantly affect the eaten rate of seeds after rodent-removal. The burial rate of seeds after rodent-removal (BRAR) was significantly higher in the secondary forest site than in shrubs site (Z=-2.88,P = 0.004). For example, the highest BRAR for the seeds covered by soil in shrubs site was only 5.56%. In secondary forest site, however, the highest BRAR under the treatment of litterfall removal reached 9.26%. The average distance of seeds eaten after rodent-removal in shrubs site (3.01 m) was significantly higher than that in secondary forest site (2.13 m) (Z=-2.080,P = 0.038), while the average distance of seeds buried after rodent-removal in shrubs site was shorter than in secondary forest site, although no significant difference was examined between them.