JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2021, Vol. 45 ›› Issue (4): 159-166.doi: 10.12302/j.issn.1000-2006.202003027

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The hydraulic characteristics of the whole branch and its components of the major tree species in the eastern region of northeast China

JING Shuo(), SUN Huizhen*()   

  1. Ministry of Education Key Laboratory of Sustainable Forest Ecosystem Management, Center for Ecological Research,School of Forestry, Northeast Forestry University, Harbin 150040, China
  • Received:2020-03-10 Accepted:2020-06-22 Online:2021-07-30 Published:2021-07-30
  • Contact: SUN Huizhen E-mail:664042498@qq.com;sunhz-cf@nefu.edu.cn

Abstract:

【Objective】The divergence in wood types between coniferous and broadleaved tree species is expected to lead to significantly different hydraulic architectures between these two functional groups. Despite extensive research on branch xylem, the hydraulic conductance of the whole branch and its parts between the two groups are not well understood.【Method】In the present study, the hydraulic conductance and the hydraulic relative resistance (the inverse of conductance) of the whole branch (Kwb), leafless branch (Kb), leaf blades (Klb), and petioles (KP)as well as the above values normalized by leaf area (Kwb-area, Kb-area, Klb-area) and dry mass (Kwb-mass, Kb-mass, Klb-mass), were determined in the quasi-steady-state mode using a high-pressure flow meter (HPFM). This was performed on three conifers (Pinus koraiensis, Picea koraiensis, Larix gmelinii) and four deciduous broadleaved tree species (Betula platyphylla, Acer mono, Ulmus japonica, Quercus mongolica) commonly found in the eastern region of northeast China. We analyzed the hydraulic resistance distribution of the whole branch, compared hydraulic conductance values within the same part of the branch among the different tree species, wood properties, or leaf habits, and established the relationship between the hydraulic conductance and leaf traits(leaf mass per area-LMA and leaf dry mass content-LDMC).【Result】The Klb for Pinus koraiensis was approximately four times as much as the Kwb and Kb, whereas the Klb and Kwb for the remaining six species were similar, and significantly lower than those of the Kb. The leaf-blade relative resistance (Rlb) in Pinus koraiensis accounted for 20% of the total hydraulic resistance (Rwb) in the branch, whereas the relative resistance contribution of Rlb, leafless branch (Rb), and petiole (Rp) to the Rwb ranged from 61% to 80%, about 20%, and lower than 10%, respectively, for the remaining tree species. The Klb-area of the non-porous species was higher than those of the diffuse- and ring-porous species. The latter two functional groups showed no significant difference in the Klb-area, resulting in a significantly higher Klb-area for coniferous species than for that of broadleaved species. No differences was found in terms of the Kwb-area or Kb-area among tree species with different wood types or leaf habits. Leaf area-based hydraulic conductances were positively correlated with the LMA or LDMC, whereas leaf mass-based hydraulic conductances were negatively correlated with the LMA and LDMC. The Klb-area and Klb-mass showed a strong and a weak relationship with leaf traits, respectively.【Conclusion】The whole branches or leaf blades with petioles could be used to measure the Klb for all the tree species examined, with the exception of Pinus koraiensis. The Klb of coniferous species was higher than that of broadleaved tree species, which compensated for the lower xylem hydraulic efficiency, to some extent. Caution should be applied when analyzing the relationship between the Klb-area and leaf traits using the whole branch for coniferous tree species. Leaf mass-based hydraulic conductance can faithfully reflect the relationship between the leaf hydraulic conductance and the leaf traits of coniferous and broadleaved trees.

Key words: hydraulic conductance, coniferous tree, broadleaved tree, whole branch and its components, leaf trait, high-pressure flowmeter, northeast China

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