动物对花楸树种实的取食与传播

花楸树是我国东北林区重要的非木质资源树种，其种实既有自然散布方式，也有动物散布方式.本文通过对花楸树种实散布过程中动物活动特点的研究，探索动物取食和传播花楸树种实的规律及其对花楸树天然更新的影响.在2008和2009年花楸树果实成熟期，通过定期观察取食花楸树果实的鸟类及其取食方式，确定对花楸树果实有拜访行为的鸟类有8种，其中食果肉鸟类斑鸫、灰喜鹊和白背啄木鸟对花楸树种实有传播作用，它们对花楸树果实的拜访频率分别为54%、12%和7%，取食后第一落点集中于距离母树5～10 m之间（占68.2%），其次为距离母树5 m以内（占27.3%），距离母树10 m以外的比例很小（占4.5%）.果实在鸟类消化道内的滞留时间可达20 min，表明潜在传播距离会很长.人工摆放果实和种子试验表明，在不同生境地面摆放的果实6～7 d内全部消失，果实的取食者主要是啮齿类和地面取食的鸟类，取食率均较高（50%～70%）；种子的取食者为啮齿类、地面取食的鸟类和蚁类，取食率均较低（1%～5%）.花楸树为多种动物提供食物，而动物为花楸树传播种子，动物的取食对花楸树的天然更新有重要影响.

Animal predation and dispersal of Sorbus pohuashanensis fruits and seeds

Sorbus pohuashanensis is an important non-timber tree species in Northeast China. There are two approaches for its fruit- and seed dispersal, i.e., natural dispersal and animal dispersal. In this paper, a field observation was conducted to study the characteristics of animal predation and dispersal of S. pohuashanensis fruits and seeds, and the effects of the predation and dispersal on the natural regeneration of the tree species. During the fruit-ripening stage of S. pohuashanensis in 2008 and 2009, there were 8 species of birds visiting S. pohuashanensis fruits, among which, three pulp-eating species Turdus naumanni, Cyanopica cyana, and Dendrocopos leucotos could disperse S.pohuashanensis seeds. The visiting frequency of the three species to S. pohuashanensis fruits was 54%, 12%, and 7%, respectively, and the first stop spotafter predation was mainly within 5-10 m away from the visited trees (with a proportion of 68.2%), secondly within 5 m (27.3%), and only 4.5% was out of 10 m. The retention time of S. pohuashanensis fruits in the digestive tract of the bird dispersers was up to 20 min, implying a long potential dispersal distance. Fruit- and seed placement tests showed that the fruits artificially placed in different habitats were disappeared within 6-7 days, and the fruit predators on the ground were mainly rodents and ground-feeding birds, with the predation rates being 50%-70%, while the seed predators on the ground were rodents, ground-feeding birds, and ants, with the predation rates only 1%-5%. S. pohuashanensis could provide food for a variety of frugivorous animals, and in return, the animals could disperse S. pohuashanensis seeds, which might have profound effects on the natural regeneration of S. pohuashanensis.