Effects of thinning and understory removal on water use efficiency of Pinus massoniana: evidence from photosynthetic capacity and stable carbon isotope analyses
{"title":"Effects of thinning and understory removal on water use efficiency of Pinus massoniana: evidence from photosynthetic capacity and stable carbon isotope analyses","authors":"Ting Wang, Qing Xu, Beibei Zhang, Deqiang Gao, Ying Zhang, Jing Jiang, Haijun Zuo","doi":"10.1007/s11676-023-01666-7","DOIUrl":null,"url":null,"abstract":"<p>Understanding the relationship between forest management and water use efficiency (WUE) is important for evaluating forest adaptability to climate change. However, the effects of thinning and understory removal on WUE and its key controlling processes are not well understood, which limits our comprehension of the physiological mechanisms of various management practices. In this study, four forest management measures (no thinning: NT; understory removal: UR; light thinning: LT; and heavy thinning: HT) were carried out in <i>Pinus massoniana</i> plantations in a subtropical region of China. Photosynthetic capacity and needle stable carbon isotope composition (<i>δ</i><sup>13</sup>C) were measured to assess instantaneous water use efficiency (WUE<sub>inst</sub>) and long-term water use efficiency (WUE<sub>i</sub>). Multiple regression models and structural equation modelling (SEM) identified the effects of soil properties and physiological performances on WUE<sub>inst</sub> and WUE<sub>i</sub>. The results show that WUE<sub>inst</sub> values among the four treatments were insignificant. However, compared with the NT stand (35.8 μmol·mol<sup>−1</sup>), WUE<sub>i</sub> values significantly increased to 41.7 μmol·mol<sup>−1</sup> in the UR, 50.1 μmol·mol<sup>−1</sup> in the LT and 46.6 μmol·mol<sup>−1</sup> in HT treatments, largely explained by photosynthetic capacity and soil water content. Understory removal did not change physiological performance (needle water potential and photosynthetic capacity). Thinning increased the net photosynthetic rate (<i>A</i><sub>n</sub>) but not stomatal conductance (<i>g</i><sub>s</sub>) or predawn needle water potential (<i>ψ</i><sub>pd</sub>), implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability. In general, thinning may be an appropriate management measure to promote <i>P. massoniana</i> WUE to cope with seasonal droughts under future extreme climates.</p>","PeriodicalId":15830,"journal":{"name":"Journal of Forestry Research","volume":"165 1","pages":""},"PeriodicalIF":3.4000,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Forestry Research","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1007/s11676-023-01666-7","RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"FORESTRY","Score":null,"Total":0}
引用次数: 0
Abstract
Understanding the relationship between forest management and water use efficiency (WUE) is important for evaluating forest adaptability to climate change. However, the effects of thinning and understory removal on WUE and its key controlling processes are not well understood, which limits our comprehension of the physiological mechanisms of various management practices. In this study, four forest management measures (no thinning: NT; understory removal: UR; light thinning: LT; and heavy thinning: HT) were carried out in Pinus massoniana plantations in a subtropical region of China. Photosynthetic capacity and needle stable carbon isotope composition (δ13C) were measured to assess instantaneous water use efficiency (WUEinst) and long-term water use efficiency (WUEi). Multiple regression models and structural equation modelling (SEM) identified the effects of soil properties and physiological performances on WUEinst and WUEi. The results show that WUEinst values among the four treatments were insignificant. However, compared with the NT stand (35.8 μmol·mol−1), WUEi values significantly increased to 41.7 μmol·mol−1 in the UR, 50.1 μmol·mol−1 in the LT and 46.6 μmol·mol−1 in HT treatments, largely explained by photosynthetic capacity and soil water content. Understory removal did not change physiological performance (needle water potential and photosynthetic capacity). Thinning increased the net photosynthetic rate (An) but not stomatal conductance (gs) or predawn needle water potential (ψpd), implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability. In general, thinning may be an appropriate management measure to promote P. massoniana WUE to cope with seasonal droughts under future extreme climates.
期刊介绍:
The Journal of Forestry Research (JFR), founded in 1990, is a peer-reviewed quarterly journal in English. JFR has rapidly emerged as an international journal published by Northeast Forestry University and Ecological Society of China in collaboration with Springer Verlag. The journal publishes scientific articles related to forestry for a broad range of international scientists, forest managers and practitioners.The scope of the journal covers the following five thematic categories and 20 subjects:
Basic Science of Forestry,
Forest biometrics,
Forest soils,
Forest hydrology,
Tree physiology,
Forest biomass, carbon, and bioenergy,
Forest biotechnology and molecular biology,
Forest Ecology,
Forest ecology,
Forest ecological services,
Restoration ecology,
Forest adaptation to climate change,
Wildlife ecology and management,
Silviculture and Forest Management,
Forest genetics and tree breeding,
Silviculture,
Forest RS, GIS, and modeling,
Forest management,
Forest Protection,
Forest entomology and pathology,
Forest fire,
Forest resources conservation,
Forest health monitoring and assessment,
Wood Science and Technology,
Wood Science and Technology.