木本、草本层迥异的用水策略与荒漠生态系统碳水过程

荒漠生态系统木本-草本双层植物群落结构，迥异的用水策略是探究气候变化对荒漠生态系统碳水过程影响的“天然实验室”。我们对荒漠生态系统碳水过程的机理性认识仍然受到木本、草本层用水策略的不同和生理生态响应差异的制约，从而极大的增加了陆地生态系统碳水循环模型预测的不确定性。本项目以温带荒漠-古尔班通古特沙漠为研究区域，结合降水控制实验与地下水位梯度带，通过观测木本、草本层及生态系统碳水通量，同时监测植物物候、叶片生理、个体形态和生物群落结构，揭示水分变化驱动下木本、草本层的生理生态响应及其对荒漠生态系统碳水过程影响的内在机理。基于近20年碳水通量观测数据，解析水分变化驱动下荒漠生态系统对碳水过程的反馈机制。为陆地生态系统碳水循环模型提供参数估计，为我国荒漠-绿洲复合体的可持续发展提供决策支持。

Desert ecosystem with woody and herbaceous layers and different water use strategy created an unique opportunity to study the effects of climate change on carbon and water processes. However, the mechanisms of carbon and water cycling are still constrained by differences in water use and ecophysiological response between growth forms, which increase uncertainty in predicting the climate change effect on ecosystem water and carbon cycling. This project will carry out at a typical temperate desert ecosystem in northwestern China, by combining precipitation manipulation experiment with experiment on a natural gradient in groundwater depth. Water and carbon fluxes under different treatment are measured; meanwhile, plant phenology, leaf-level physiological processes, individual morphological parameters, and the community structure of plants and microorganisms are monitored. When ecosystem water availability changes, the response of ecosystem carbon and water processes and the differences in growth forms will be monitored. 20 year’s carbon and water fluxes will be used to quantify carbon and water processes and their response to water changes. The results will facilitate model projections on ecosystem carbon and water cycling under climate change scenario and also have significant implications for the sustainable and adaptive management of the desert-oasis system in northwestern China.