生物由水向陆演变，诞生了拥有根和气孔的维管植物，开始了土壤水分经植物以水汽形式进入大气的过程而根本改变地球的水文、气候和生态，是地球系统适应气候变化的生理驱动力。水汽是最重要的温室气体，生态系统正是通过调整水汽通量适应环境的变迁。目前的主流技术未能有效区分陆表水汽通量中比例和变异最大的气孔蒸腾和相对固定的表面蒸发，加上气孔对环境变化的敏感性和受树木水力性状的制约，人们对森林冠层与大气的水汽交换及其水文效应的认识存在争议。基于已往的研究积累，我们提出“水力性状间的协同适应是气孔控制冠层水汽通量的最优行为策略”的观点，依托南亚热带全球变化因子梯度变化平台并结合野外控制实验，研究和阐明以树干液流整合的森林冠层水汽通量对全球变化因子响应的生物学驱动机制及水文效应。研究结果有助于减少气候模型预测的不确定性和降低水资源系统对气候变化的脆弱性，最终服务“增强生态系统适应和应对气候变化的能力”的国家需求。

As plants transitioned from water to land, the evolution of vascular plants with roots and stoma marked the beginning of direct movement of soil water into the atmosphere via plants. Subsequently, this process has radically changed the hydrological cycle, climate and ecology of the planet. Plant transpiration is therefore considered a key physiological means for adaptation of the earth system to climate change. Ecosystems respond and acclimate themselves to environmental transitions by adjusting their water vapor flux. The inability of current technologies to separate plant transpiration – the largest fraction of land surface vapor flux – from evaporation, combined with stomatal sensitivity to a changing environment and the constraint of hydraulic traits, means there is great uncertainty about the vapor exchange between forest canopy and atmosphere and its regional hydrological effect. Based on previous research, we propose that the adaptive coordination between hydraulic traits can be explained in terms of an optimal stomatal strategy for controlling canopy vapor flux. By establishing a global change factor research transect in lower subtropical China and controlled experiments in the field, we will study the driving mechanisms of sap flow - integrated forest canopy vapor flux in response to global change factors and its hydrological effects. These research results are expected to reduce uncertainty in climate modeling and in the predictions of the response of water resource systems to climate change, and to address the state interest in “Enhancing adaptability and coping ability of ecosystems to climate change”.