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### 干旱胁迫下木本植物水力系统的响应机制

1. 1. 东北林业大学生态研究中心
2. 东北林业大学生态研究中心, 哈尔滨 150040
3. 东北林业大学
• 收稿日期:2021-03-25 修回日期:2021-08-17 发布日期:2021-08-26
• 通讯作者: 王传宽
• 基金资助:
中央高校基本科研业务费专项资金项目;国家“十三五”重点研发计划项目;教育部长江学者和创新团队发展计划

### Response mechanism of hydraulic system of woody plants to drought stress

Dan-dan Luo1,Chuan-Kuan WANG 3

• Received:2021-03-25 Revised:2021-08-17 Published:2021-08-26
• Contact: Chuan-Kuan WANG
• Supported by:
Fundamental Research Funds for the Central Universities;National Science and Technology Support Program of China;Program for Changjiang Scholars and Innovative Research Team in University

Abstract: Drought-related tree mortality profoundly impacts ecosystem functions and the carbon budget, in which the principal mechanism involved has been suggested to be the catastrophic failure of the hydraulic systems. However, our understanding of tree hydraulic systems and the mechanisms of tree death during extreme drought conditions are limited because the responses of trees to drought stress are multi-dimensional and complex. In this review, we first integrated the general response process of woody plants to drought stress. Second, we expounded the indexes of measuring plant drought resistance, focusing on stomatal safety margin (SSM) that can be used to comprehensively evaluate the drought tolerance of plant. The large positive values of SSM indicate a stronger coordination ability between stomata and hydraulic traits, a lower possibility of xylem embolization, and a more conservative hydraulic strategy. After that, we introduced the response mechanisms of different plant organs (leaf, stem and root) to drought stress. The probability of reaching the critical threshold and duration of tree death was determined by the interaction of physiological and morphological traits. Finally, we discussed the hydraulic recovery mechanisms of woody plants, and put forward three research priorities in future: (1) to improve the methodology for measuring leaf hydraulic conductance (xylem and outside the xylem hydraulic conductance), and quantify the relative contributions of the four water transport pathways in mesophyll tissues; (2) to quantify the variation in epidermal permeability for better understanding plant water-use strategies; and (3) to improve vegetation dynamics models by considering the water-carbon coupling mechanisms, and link the structural and physiological traits of individual species up to the patterns and processes of communities and landscapes, so as to better assessing and monitoring the risk of drought-induced tree mortality.