青藏高原正经历着快速的气候变暖，这将对高寒草地植物物候产生深远的影响。目前物候的研究多关注于植物地上部分，作为影响水分和营养吸收能力的关键因子，地下物候如何响应气候变暖却鲜有报道。而且，当前大多数陆面过程模型采用地上物候参数代替地下物候特征模拟生态系统过程，从而引起预测的不确定性。采用根系生物量的季节动态定义地下物候是常见的物候研究方法。本项目拟利用2010年建立的青藏高原高寒草地“增温-降水改变”野外控制实验平台，采用多光谱相机、地上生物量拟合法和微根管法分别监测群落地上和地下物候，探讨群落地上、地下物候对气候变暖的响应。同时结合中型物种水平增温实验监测优势物种物候，揭示气候变暖条件下优势物种物候特征改变和群落组成改变对群落物候变化的相对贡献。本研究将深化人们对高寒草地植物地下物候响应气候变暖机制的认识，有助于陆面过程模型框架的完善，并为高寒草地适应性管理提供科学依据。

The Tibetan Plateau is experiencing a rapid climate warming, which will strongly influence plant phenology. To date, the bulk of phenological studies have focused on the plant aboveground aspect. However, it remains unclear how belowground phenology responds to climate warming, although plant belowground phenology is a key factor in affecting water and resource acquisition. Most of the terrestrial biosphere models use aboveground phenology as a surrogate of whole plant phenology to simulate ecosystem processes, which can lead to the uncertainties of the prediction. This project will be mainly conducted on a warming-by-precipitation platform in an alpine grassland on the Tibetan Plateau. We aim to explore the effects of warming on above- and below-ground phenology by using multispectral camera, a non-destructive sampling method and minirhizotrons to monitor above- and below-ground community phenology. We will elucidate the relative contributions of changes in dominant species phenology and species composition to the warming-induced changes in community phenology by using a species-level warming experiment for dominant species. This project will help us understand the underlying mechanisms for the effects of climate warming on plant phenology, improve the framework of process-based ecosystem models and provide practical advice for the management of alpine grasslands under future climate warming.