北方荒漠带优势灌木水力“安全-效率”权衡沿降水梯度的分异规律

Embolism resistance of hydraulic system, reflects the plants’ adaptation to the environment and the optimal evolution result of ongoing hydraulic ‘safety-efficiency’ tradeoffs, is the key factor for defining the limitation of drought tolerance of woody plants, and for predicting forests dynamics on global scale. It’s also the crux in the large-scale study of forest mortality. Inspection plant hydraulic properties and the ‘safety-efficiency’ tradeoffs as well as their spatial differentiation law, therefore, are of great theoretical and practical significance. This project intends to perform among moisture gradients of Chinese deserts zones, taking the constructive and dominant shrubs species of each sampling site as the research objects, integrating experimental and physiological ecology methods to examine properties of hydraulic function and structure, to test the interspecific and site-based differences of embolism resistance, to quantifies the index of ‘safety-efficiency’ tradeoffs, and to analyze the response and adaptation of the index to water spatial heterogeneity. It finally could reveal the ‘hydraulic failure’ risk of different vegetations, and provide theoretical basis and evidences for predicting vegetation dynamics and ecosystem functions in arid areas under climate change.

水力系统栓塞抗性，反映了植物适应外界环境、不断进行水力“安全-效率”权衡的最优进化结果，是定义木本植物耐旱极限以及在全球尺度上预测森林动态的关键，也是目前大尺度森林死亡研究中的症结所在。因此，检验植物水力性状及“安全-效率”权衡的空间分异规律有重要的理论和现实意义。本项目拟在中国荒漠水分梯度带展开，以各样点建群和优势种灌木为研究对象，综合运用实验生态学、生理生态学方法研究植物水力系统功能和结构特性，检验栓塞抗性的种间及样点间平均水平差异，量化出建群种水分利用的“安全-效率”权衡指数，分析权衡指数对水分空间异质性的响应和适应，揭示不同区域植被“水力失效”风险，为气候变化下干旱区植被动态及生态系统功能预测提供理论基础和依据。