温度和降雨量变化对青藏高原高寒草甸土壤种子库的直接和间接作用机理

全球气候变化研究往往关注其对地上植被的作用，而对保存于地下的土壤种子库（潜在植被）的影响往往被忽视。近年有研究表明：一些物种利用种子库采取的“双面下注对策”和“风险分摊机制”会因未来全球气候变化而遭受破坏，因而增加了物种局部灭绝的可能性。本项目拟通过人工控制和野外调查实验，重点研究温度和降雨量变化对种子库中休眠种子萌发和物种组成的影响，确定气候变化对种子库的直接作用；通过分析温度和降雨量变化对土壤真菌活力的作用，及真菌活力与种子库损耗的关系，揭示气候变化通过影响土壤真菌而对种子库产生的间接作用；通过分析温度和降雨量变化对地上植被组成、种子产量，及地上植被与种子库物种组成关系的作用，确定气候变化通过地上植被而对种子库产生的间接作用，以及气候变化对种子库与地上植被动态关系的影响，进而阐明温度和降雨量变化对种子库的直接和间接作用机理，从而为青藏高原高寒地区植被保护和恢复提供理论依据和技术支撑。

The research of global climate change ecology often only focus on aboveground vegetation, however, how its influence on soil seed bank (potential vegetation) is often neglected. Recently, some research showed that the ‘bet-hedging strategy’ and ‘spreading risk strategy’ that some species use in soil seed bank would be destroyed by future global climate change, hence, the change in the dynamics of soil seed banks increase the risk of local extinctions of these species. In this project, we want to use control experiment and field investigation research to explore the direct effect of climate change on soil seed bank composition through analysis the effect of temperature and precipitation change on dormancy seeds germination and species composition of seed bank. We want to clarify the indirect effect of climate change on soil seed bank through research the direct effect of temperature and precipitation change on soil fungal pathogens and explore the relationship between soil fungal pathogens activities and soil seed bank depletion. We also want to clarify the indirect effect of climate change on soil seed bank and dynamic relationship between soil seed bank and aboveground plant community through explore the direct effect of temperature and precipitation change on species composition and seed output of aboveground plant communities, and relationship between seed bank and aboveground plant community. Finally, we can clarify the mechanism of direct and indirect effect of climate change on soil seed bank. Based on the above information, we can also supply a theoretical bases and technical support to grassland ecosystem protection and restoration on the Tibetan Plateau.