Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (9): 925-941.DOI: 10.17521/cjpe.2021.0111

• Review •     Next Articles

Response mechanisms of hydraulic systems of woody plants to drought stress

LUO Dan-Dan, WANG Chuan-Kuan(), JIN Ying   

  1. Center for Ecological Research, Northeast Forestry University, Harbin 150040, China
  • Received:2021-03-25 Accepted:2021-06-29 Online:2021-09-20 Published:2021-11-18
  • Contact: WANG Chuan-Kuan
  • Supported by:
    Fundamental Research Funds for the Central Universities(2572018AA07);National Key R&D Program of China(2016YFD0600201);Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R09)


Drought-related tree mortality profoundly impacts the ecosystem functions and carbon budgets, in which one of the principal mechanisms involved is the catastrophic failure of the hydraulic systems. However, our understanding of tree hydraulic systems and the mechanisms of tree death under extreme drought conditions are limited because the responses of trees to drought stress are multi-dimensional and complex. In this review, we first expounded the indexes of measuring plant drought resistance, and focused on the stomatal safety margin (SSM) that can be used to comprehensively evaluate the drought tolerance of plants. A larger positive value of SSM indicates a stronger coordination between stomata and hydraulic traits, a lower possibility of xylem embolization, and a more conservative hydraulic strategy adopted. Second, we integrated general response processes of woody plants to drought stress. Third, we introduced response mechanisms of different plant organs (leaf, stem and root) to drought stress. The probability of reaching the critical threshold and the duration of tree death are determined by interactions between physiological and morphological traits. Finally, we discussed hydraulic recovery mechanisms of woody plants, and put forward three research priorities in the future: (1) to improve the methodology for measuring leaf hydraulic conductance, especially the xylem and outside-xylem hydraulic conductance, and quantify the relative contributions of the four water transport pathways in mesophyll tissues; (2) to quantify variations in the epidermal permeability for better understanding plant water-use strategies; and (3) to deepen the understanding of the water-carbon coupling mechanisms, and link individual-level structural and physiological traits with patterns and processes at the community and landscape levels, so as to better assessing and monitoring the potential risk of drought-induced tree mortality.

Key words: drought resistance, xylem embolism, stomatal adjustment, tree mortality, hydraulic trait