青藏高原高寒草地正经历着以温暖化为特征的气候变化，这将对植物的物候和生活史产生重要影响。遥感监测发现，从上世纪80年代以来，高寒草地的返青期提前，但也有研究发现不同的结果，目前缺少物候的实测证据。本申请利用在青海海北高寒草地建立的“增温-降水”控制实验，结合人工气候室光周期控制实验，试图回答(1) 水热变化及其交互作用是如何影响高寒草地植物的有性生殖？(2) 植物开花物候对气候变化响应的差异，是否是由于对光周期的敏感性不同造成的。为此，设计的研究内容为：增温和降水控制对高寒草甸主要植物开花物候、果期物候以及繁殖输出的影响、光周期类型与植物开花物候对增温响应的关系、以及增温和降水控制对开花物候和繁殖输出的影响机理。通过这些研究，揭示青藏高原温暖化和降水格局的改变如何通过影响植物的繁殖，探讨植物的光周期敏感性在对气候变化响应中的作用，为理解群落结构和种群动态对气候变化的响应提供机理上的解释。

The Tibetan alpine grassland is undergoing rapid climate warming, which will have large impact on plant phenology and life history. The monitoring from remote sensing has revealed that the green-up dates in the Tibetan Plateau have continuously advanced since 1980s. However, different results have also been reported. Nevertheless, there is no direct field evidence. In the current project, using "warming-by-precipitation" experiment, together with photoperiod controlled experiment, we intend to address two issues: (1) how is the sexual reproduction of alpine plants influenced by water and temperature regimes? (2) Is there any association between the responses of flowering phenology to climate warming and plants’ sensitivity to photoperiod? For this purpose, we will focus on the following issues: (1) The impact of warming and precipitation on the flowering phenology, fruit phenology and reproduction output of the alpine plants; (2) The relationship between the types of plant photoperiod and their responses to climate warming; (3) The underling mechanism of mechanism of plant responses to climate change. Studies from the current project will shed lights on our understanding of the species shift under future climate change.