青藏高原草地土壤-植被互馈关系及其空间异质性机理

The relationship between soil and vegetation of different ecosystems and its spatial pattern is a key but poorly understood topic. This project will be carried out at main grassland ecosystems, including alpine meadow, alpine steppe, alpine desert steppe and alpine shrub grassland, in Qinghai-Tibet Plateau. Through a large-scale investigation on natural vegetations and a spatially multi-site study on control plant communities under different treatments (e.g. grazing and fertilization), we will consider the temporal and spatial pattern of soil organisms (e.g. nematode and microorganism), soil properties (e.g. carbon, nitrogen, phosphorus and water content) and their function, the structure, dynamics and species diversity of grassland communities, and functional traits of component grassland species. In particular, the project will determine the effect of vegetation on soil ecosystem process (i.e. soil properties and the structure, dynamics and function of soil organism community), the effect of soil ecosystem process and soil seed bank on the structure, dynamics and function of grassland communities, and their responses to disturbances (i.e. nutrient addition, species adjustment and grazing control). For this, we want to find the form, principle, and spatial pattern of the relationship between vegetation and soil for different alpine grassland ecosystems, and then try to provide ecological basis and technical supports for rational utilization and effective management of grassland and restoration of degraded grassland.

不同生态系统土壤与植被的相互关系及其空间格局是近年来国际地学界和生态学界高度关注而尚未解决的关键问题。本项目以青藏高原包括高寒草甸、高寒草原、高寒荒漠草原和山地灌丛草地等四种主要高寒草地生态系统为对象，通过大尺度野外调查和多点人工控制实验，从土壤生物时空分布、养分动态和功能及地上植物群落组分种的多种特性、群落结构和种多样性变化入手，重点研究不同高寒草地生态系统中地上植物对土壤生态过程（土壤养分性状、土壤生物群落结构及其功能）的影响，土壤生态过程和种子库特征对地上植物植物群落结构、动态及组分种特性的影响，以及二者对干扰（资源添加、物种变化和放牧控制）的响应机制，揭示不同高寒草地生态系统土壤/植被相互作用的形式、机理和空间变化规律，从而为青藏高原不同高寒草地生态系统合理利用和退化草地的恢复提供理论依据和技术支撑。

不同生态系统土壤与植被的相互关系及其空间格局是近年来国际地学界和生态学界高度关注而尚未解决的关键问题。本项目通过大尺度野外调查和多点人工控制实验发现：无论是地上还是地下生态系统，在大尺度上都主要受气候因素主导。在局域尺度上地上和地下的各个部分联系紧密，关系复杂。总体而言，青藏高原土壤生态系统比地上更为稳定：地下生态系统对干扰的抗性更强，且在干扰后的恢复也更快。土壤生态系统为地上植被的恢复提供了“缓冲带”，但重度的干扰会加剧破坏这种缓冲作用。地上地下对于干扰的响应也各不相同：在被干扰后，地上植被的建群倾向于环境筛选等确定性因素。而地下的丛枝菌根真菌群落则倾向于随机过程。土壤种子库则随着干扰的加重逐步接近于地上植被。不同的植被类型主要差异在地上植被的组成，而地下种子库的组成差别相对较小。本项目揭示了不同高寒草地生态系统土壤/植被相互作用的形式、机理和空间变化规律，为青藏高原不同高寒草地生态系统合理利用和退化草地的恢复提供理论依据和技术支撑。