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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (7): 194-204.doi: 10.11707/j.1001-7488.20210721

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Efficiency-Safety Relationships of Hydraulic Conducting System for Branch and Root of Three Pinus Species Growing in Humid Area

Linfeng Ye1,Yan Li1,2,3,Zhongyuan Wang1,2,3,Shitong Lu1,Tiantian Pan1,Sen Chen1,Jiangbo Xie1,2,3,*   

  1. 1. State Key Laboratory of Subtropical Silviculture Zhejiang A & F University Hangzhou 311300
    2. State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences Urumqi 830011
    3. College of Forestry and Biotechnology, Zhejiang A & F University Hangzhou 311300
  • Received:2020-08-20 Online:2021-07-25 Published:2021-09-02
  • Contact: Jiangbo Xie

Abstract:

Objective: The decline and even death of vegetation caused by drought are not limited to arid areas. Species growing in humid areas have weak adaptation to drought, and thus are more likely to die from hydraulic failure. Establishing quantitative relationship between xylem anatomy and hydraulic function(including hydraulic efficiency and safety) at organ level of vascular plants is the key to understand the drought-induced mortality mechanism for plants growing in humid areas. Method: Pinus massoniana, P. parviflora and P. elliottii were sampled to determine the hydraulic function(hydraulic conductivity, embolism resistance) and anatomical structures(tracheid traits, pit traits, etc.) of branch and root xylem. Combined with data from published studies, the trade-offs between hydraulic efficiency and hydraulic safety of branch and root for Pinus were examined; And the structural basis of xylem hydraulic efficiency(Ks, sapwood-specific hydraulic conductivity) and embolism resistance(P50, xylem water potential causing 50% loss of hydraulic conductivity) were analyzed quantitatively. Result: 1) For the three Pinus species, Ksr(root Ks) > Kss(branch Ks), root P50 > branch P50; Kss was positively correlated with Ksr, branch P50 and root P50 were also positively correlated; All the three species showed low efficiency and low safety. 2) Correlation analysis revealed that: Kss was negatively correlated with branch P50, branch exhibited an efficiency-safety trade-off. The correlation coefficient between Ksr and root P50 was close to 0(R2=0.01, P=0.94), there was no trade-off in root. Functional trade-off was determined by anatomical structure: Kss and branch P50 had different structural requirements(there was an efficiency-safety trade-off in branch), while Ksr and root P50 had similar structural requirements(there was no trade-off in root). 3) Redundancy analysis revealed that: Kss was best interpreted by branch pit membrane area; Branch pit torus area had the highest interpretation for branch P50; Ksr was best interpreted by root wood density; Root pit margo area had the highest interpretation to root P50. Conclusion: Hydraulic efficiency and embolism resistance of branch and root were mainly determined by anatomical structure, of which pit had the greatest influence, followed by wood density and tracheid wall thickness. This study demonstrated that there was an efficiency-safety trade-off in branch, but not in root. The anatomical structural bases behind this are: If the structural requirements are different, there is a trade-off between efficiency and safety, while the structural requirements are similar, then no trade-off.

Key words: Pinus massoniana, Pinus parviflora, Pinus elliottii, xylem structure, efficiency-safety trade-off, embolism, vulnerability curve, hydraulic conductivity

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