藏东南地区星鸦等分散贮藏动物对华山松种子命运的影响

In the study of animal-plant coevolution, one of the research hotspots and difficulties is quantitatively analyzing seed dispersal effectiveness of scattering hoarding animals in mutualism network, the relationships among hoarding animals in community level and their effects on plant regeneration. Seeds of chinese white pine (Pinus armandii) have typical characteristics of depending on animal dispersal but the relative studies are lacking. In Southeast Tibet forest, nutcrackers (Nucifraga caryocatactes) and other scatter hoarding animals are predators and potential dispersers of chinese white pine seeds, but there are still some questions we don’t know: (1) in species level, how do these animals have effects on the seed fate respectively? (2) in community level, whether they shape the spatial distribution pattern of chineses white pine population by scatter-hoarding behaviors of short distance migrating and stopover to wintering sites. This research will systematically investigate the components and structures in mutualism network of “chinese pines---scatter-hoarding animals ” in Southeast Tibet, determine the key species in network and quantitatively analyze their dispersal effectiveness. By detecting the non-redundancy in dispersed process of effective propagators, the impacts of these animals on seed fate and spatial distribution pattern of chineses white pines will be probed. The research results will help us understand the forming and maintaining mechanism in the animal-plant mutualistic network, and enrich the theory system of animal-plant coevolution.

定量分析动植物互惠共生网络中分散贮藏动物的种子传播有效性，从群落角度解析网络中各动物传播者相互关系，以及它们在植物更新过程中的作用，一直是动植物协同进化研究领域的热点和难点之一。华山松种子具有典型的依赖动物传播的特征，但相关研究却十分缺乏。星鸦等分散贮藏动物是藏东南林区华山松种子的捕食者和潜在传播者，但我们并不清楚：（1）从个体的角度，它们是如何影响华山松种子命运的？（2）从群落的角度，它们在短距离迁徙越冬停歇地的传播行为是否塑造了华山松种群空间分布格局？本研究拟通过系统调查该地区“华山松—动物传播者”互惠共生网络的组成和结构，从促进更新和限制更新两个方面，确定网络中传播关键种，并定量分析其种子传播有效性，通过解析各有效传播者的传播非冗余性，揭示动物传播者对华山松种子命运和空间分布格局的影响。研究结果将有助于我们对动植物互惠共生网络形成和维持机制的理解，丰富动植物协同进化理论体系。

华山松种子具有典型的依赖动物传播的特征，但一直以来鲜见报道。本项目选择在藏东南的原始华山松林内进行，应用红外相机监测技术和样方法，解析华山松种子传播网络的组成，并从有效传播者的角度确定该网络中的关键种。研究结果显示：1)藏东南取食华山松种子的鸟兽多达24种，多为地面取食者，树冠取食者仅星鸦、红嘴蓝鹊等4种鸟类，具分散贮藏行为的仅有星鸦；2)华山松种子虽然具有动物传播的典型特征，但其主要传播方式是重力传播，其种子雨特征和球果形状具有典型的防范动物捕食特点，贮点样方实验和华山松林年龄结构测定结果也支持这一结论；3)华山松林下星鸦建立的贮点数量非常少，对华山松种子传播与更新的作用很小，星鸦并不是华山松的有效传播者，藏东南地区华山松与动物之间尚未建立稳定有效的动植物互惠传播网络。