近地层臭氧（O3）浓度持续升高改变了温带森林树木水分利用和蒸腾作用，但O3对树木蒸腾耗水和水分传导的影响机制仍未明晰。阐明O3浓度升高对树木整株水分平衡的影响程度和机制，对于认识与应对O3污染对森林生态系统的负作用具有重要意义。本研究以长白山森林不同敏感性树种（白桦、黄菠萝、水曲柳、蒙古栎）为对象，研究冠层蒸腾作用和气孔导度对O3浓度升高的响应动态和规律；将叶片的水力学性状与植株茎干、根部的木质部导管结构和导水能力相结合，揭示O3浓度升高对树木整体水分传导和水分平衡的影响机理，考虑到气态水蒸腾和液态水分传导之间的耦联作用，探讨不同O3浓度条件下树木水力结构特征和光合生理特征之间的关联关系，阐明长期生长在高浓度O3下的树木应对偶然极端干旱事件的响应差异及机制，从水分生理角度为理解O3浓度升高对森林树木生理学功能的影响提供参考，为合理预测未来森林群落组成和演替提供理论基础。

The increasing ground-level ozone concentration has caused adverse effects on the productivity and water use efficiency of temperate forest. However, the effect and mechanisms of ozone effect on whole-tree transpiration water use process and water balance are poorly understood. In Northeast China, the rapidly increasing ozone concentration has caused significant impacts on forest tree species. Because water in the xylem is transported through a complex net-work of vessels in plants, this study will explore possible underlying eco-physiological mechanisms of whole-tree level water balance to elevated ozone, and assess the influence of elevated ozone pollution on long- distance water transport in temperate forest tree species. Based on the ozone sensitivity analysis, the seedlings of dominant tree species in broad-leaved Korean pine forests of Changbai Mountain will be exposed to different ozone concentrations in open-top chambers based on the ozone sensitivity analysis. This study focuses on (1) Contrasting and analyzing the dynamic responses of transpiring water consumption and xylem water transport at whole-tree level among four tree species with differing ozone sensitivity. (2) According to the co-ordination between gaseous water transpiration and liquid hydraulic conductance, the relationships between photosynthetic characteristics and hydraulic architecture are investigated. (3) Clarifying the extent and underlying mechanisms of the effect of elevated ozone on hydraulic architecture at the whole-tree level in terms of leaf hydraulic characteristics, the xylem vessel structure of stem and root, hydraulic conductance and xylem anatomical feature. (4) Identifying the different responses and water physiological mechanisms of tree species growing under elevated ozone exposure to extreme drought event. The objectives of the research are to provide (1) a scientific basis for comprehensive understanding the effect of ozone on the physiological function of forest trees from the point of view of water physiology, and (2) a theoretical basis for reasonable prediction of population dynamics, community composition and species diversity of temperate forest.