全球变化背景下青藏高原多年冻土退化对高寒草地的影响研究

项目名称： 全球变化背景下青藏高原多年冻土退化对高寒草地的影响研究

项目编号： No.41271089

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 宜树华

作者单位： 中国科学院寒区旱区环境与工程研究所

项目金额： 85万元

中文摘要： 过去几十年，青藏高原部分地区的高寒草地发生了退化。有研究认为，过载过牧是高寒草地退化的主要原因；也有研究认为，气候变暖、多年冻土退化会导致地下水位下降，表层土壤变干，从而使高寒草地发生逆向演替，发生退化。但多年冻土退化对地下水的影响存在阶段性和空间差异性，因而对高寒草地的影响也应存在着差异，不能一概而论。目前过载过牧问题已经得到了重视，并采取了一系列的措施；而在全球变化背景下，多年冻土将不可避免地发生退化，其对高寒草地到底有着什么样的影响，是迫切需要解决的问题。本项目拟以野外实地观测和试验为基础，结合不同尺度的卫星资料和遥感反演结果，通过改进我们最新开发的、在高纬度地区广泛应用的生物地球化学过程模型，从植被生长的水、热限制因子的角度阐明多年冻土退化对高寒草地的影响机制；揭示二者对气候变化的响应规律；预估不同气候变化情景下二者的变化，为国家制定青藏高原生态环境保护政策提供科学依据。

中文关键词： 青藏高原；高寒草地；多年冻土；模式模拟；遥感反演

英文摘要： Over the last few decades, the alpine grassland degraded on some regions of the Qinghai-Tibetan Plateau (QTP). Some studies attributed it to overgrazing; while some others the degradation of permafrost. It is believed that degradation of permafrost would cause lowering of water table, and drying of surface soil, then retrogressive succession, and finally degradation. However, effects of permaforst degrdation on water are different on different degradation stages, and different on different regions. Recently, overgrazing has received great concerns, and several measures have been made to deal with this issue. Under the context of global change, permafrost on the QTP will inevitably degrade.It is vital to understand the responses of alpine grassland under different stages of permafrost degradation and on different climate regions.In this study, we propose to investigate the effects of permafrost degradation on alpine grassland by integrating field observation and experiments, remote sensing, and modeling with a process-based biogeochemical model, which is developed by us and widely used in the high latitute regions.We aim to clarify the mechanism of permafrost degradation from the perspective of water and energy, which are two important limiting factors of growth of cold region ecosystems; and to reveal rules of t

英文关键词： The Qinghai-Tibetan Plateau；Alpine Grassland；permafrost；Modeling；Remote Sensing