青藏高原高寒草甸长期氮添加的级联效应

项目名称： 青藏高原高寒草甸长期氮添加的级联效应

项目编号： No.31270503

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 生物科学

项目作者： 宋明华

作者单位： 中国科学院地理科学与资源研究所

项目金额： 88万元

中文摘要： 外源性氮输入引起植被组成、物种多样性、植物光合碳分配方式、生产力等的变化已成为共识，而有关长期氮输入的级联效应（cascading effects）研究却十分缺乏。本项目基于在青藏高原高寒草甸已开展7年（2006-2012年）的氮添加实验，采用实验生态学、生理生态学、昆虫生态学、微生物生态学，以及同位素示踪技术，研究长期氮输入通过引起植物体养分含量、光合碳分配方式和植物群落组成等的变化进而对食草昆虫数量、取食行为的影响，对植物与微生物调节的土壤有效氮正反馈机制的影响，以及对凋落物分解过程的影响，阐释高寒草甸长期氮添加的级联效应的内在机制。验证假说：影响草食性昆虫适口性的植物性状能够持续存留于植物凋落物属性中，进而作用于分解者对凋落物的分解。本研究能为我们深入认识环境变化引起的生态系统各组分的作用和反馈提供新思路，增进对生态系统的响应方式的全面理解，并为制定合理的草地经营措施提供理论依据。

中文关键词： 外源性氮输入；级联效应；光合碳分配；凋落物分解；高寒草甸

英文摘要： It has been commonly recognized that nitrogen fertilization caused changes in plant community and plant growth, e.g. species composition, plant diversity, and leaf nitrogen (N) content, allocation patterns of photosynthetic productivity. However, studies on the cascading effects of N fertilization were very few. Here we plan to carry out the following studies based on a seven-year N fertilization experiment in an alpine meadow on the Tibetan Plateau: the effects of changes in leaf N content and plant species composition on quantity and feeding behavior of herbivorous consumers under the long-term N fertilization; the effects of changes in plant species composition on the positive feedback of nitrogen availability mediated by plants and microbes; and the processes of plant litter decomposition. We try to test a hypothesis: some of the leaf traits which are effective deterrents of herbivory are persistent in leaf litter and remain operational against decomposers. Our studies are very useful for better understanding the interactions and feedbacks among the sub-systems when they are in the face of environmental changes. It also provides a new way to think about the adaptations of ecosystem, and help us to avoid economic damages from explosion of herbivorous consumers in response to environmental changes and manageme

英文关键词： Nitrogen addition；ecosystem cascading effect；photosynthetic carbon allocation；litter decomposition；alpine meadow