干旱及氮沉降对温带典型草原植物群落稳定性的影响及机制

近年来全球干旱频发引起了广泛关注，但相关研究多聚焦于干旱对物种多样性、生产力及群落组成的影响，对于干旱如何影响植物群落的稳定性，尤其是稳定性的各个方面的研究却很少。氮沉降对生态系统的影响已有广泛研究，但基于干旱背景下的氮沉降效应还不明确。我国温带草原将同时面临干旱加剧和大气氮沉降增加，这些变化对植物群落稳定性的影响及其机制是当前亟待研究的问题。本项目拟在内蒙古典型草原开展控制实验，模拟降水量减半、降水频次减半、持续1个月无雨等干旱情景和大气氮沉降，通过分析土壤性状、植物及其群落相关属性对处理的响应、以及各属性之间的相互关联，进而从组成稳定性和生产力稳定性两个方面，从物种变化速率、群落相似度、时间稳定性及抵抗力、恢复力等多个角度，全面揭示干旱及氮沉降对温带典型草原植物群落稳定性的单独及交互影响以及驱动机制。本项目将提高我们对全球变化生态后果的认识和预测，有助于应对未来的气候变化。

Increase in drought frequency worldwide in recent years has aroused widespread concern. Relevant studies, however, focused on the effects of drought on species diversity, productivity and community composition, and few addressed the impacts of drought on plant community stability, especially on every aspect of stability. Although the impacts of nitrogen enrichment on ecosystems have been studied extensively, its effects under drought scenarios remain unclear. The temperate steppe in China is projected to experience increase in drought and atmospheric nitrogen deposition simultaneously in future. How these changes will affect plant community stability of the steppe and the underlying mechanisms are questions needed to be studied urgently. Using a field experiment simulating reductions in precipitation amount by 50%, in frequency of natural precipitation by 50%, one-month extreme drought, and increase in atmospheric nitrogen deposition in a temperate steppe in Inner Mongolia, we will determine the responses of soil conditions, plant and related community characters to drought and nitrogen deposition, and analyze the relationships between the variables. We aim to fully reveal the independent and interactive effects of drought and nitrogen deposition on compositional and functional stability of plant community in temperate steppe and the underlying mechanisms, from the perspectives of species change rate, community similarity, temporal stability, resistance and recovery. This study will improve our understanding and prediction of the consequences of global change, and help us cope with the future climate change.