植物生态学报

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晋西黄土区典型乔灌木短期水分利用效率对环境因子响应

韩璐,杨菲,吴应明,牛云明,曾祎明,陈立欣   

  1. 北京林业大学水土保持学院
  • 收稿日期:2021-06-09 修回日期:2021-09-02 发布日期:2021-09-18
  • 通讯作者: 陈立欣
  • 基金资助:
    国家自然科学基金

Responses of short-term water use efficiency of typical trees and shrubs to environmental factors in the Loess Area of Western Shanxi

Lu HAN1,Fei YANG2,Ying Ming WU2,Yun Ming NIU2,Yi Ming ZENG2,Lin-Xin Lin-Xin CHENCHEN   

  • Received:2021-06-09 Revised:2021-09-02 Published:2021-09-18
  • Contact: Lin-Xin Lin-Xin CHENCHEN

摘要: 【目的】为明确晋西黄土区植物的水分利用规律及对半干旱区的适应策略,提高黄土地区植被建设效益,本文对该地区典型乔灌木短期水分利用效率随环境因子变化进行探究。【方法】本研究以典型乔木油松(Pinus tabuliformis)、刺槐(Robinia pseudoacacia)及其林下灌木黄刺玫(Rosa xanthina)、杠柳(Periploca sepium)为研究对象,通过测定叶片可溶性糖稳定碳同位素比率(δ13Cleaf)与枝条渗出液稳定碳同位素比率(δ13Cbranch),计算叶片尺度下植物短期水分利用效率(WUEleaf)变化趋势,确定其对环境因子变化的响应。【主要结果】结果表明:(1)观测期间四种植物δ13Cleaf值总体呈现降低趋势,δ13Cbranch值呈现先升高后降低趋势。δ13Cleaf值在种间和生活型中均存在差异。在种间和生活型中存在差异。具体表现为:灌木>乔木,常绿乔木(油松)>落叶乔木(刺槐)。(2)四种植物WUEleaf值在观测初期保持稳定,并逐渐升高。当温度(Ta)>25℃或者饱和水汽压差(VPD)>1.0kPa时,生活型是引起四种植物之间WUEleaf值差异的主要因子,表现为:杠柳>黄刺玫>油松>刺槐。否则,环境因子取代生活型成为影响乔灌木WUEleaf值变化的主要因子,表现为:杠柳>刺槐>油松>黄刺玫。(3)WUEleaf值与Ta、相对湿度(RH)、VPD之间存在显著负相关关系Ta通过非气孔因素,即酶的作用改变光合速率,引起WUEleaf值变化。RH、VPD等水分因子则通过改变气孔开度,影响蒸腾,进而改变WUEleaf值。随着SWC的升高,WUEleaf值呈现先增加后降低的趋势。油松林和刺槐林在SWC分别达到15%-18%、13%-14%时,WUEleaf值达到最高值。经过混合线性模型(LMM)分析得到,油松和刺槐WUEleaf值主导环境因子分别为RH和VPD,黄刺玫和杠柳WUEleaf值主导环境因子均为Ta。通过本研究,得到黄土地区典型乔灌木生长季水分利用效率变化和主要环境影响因子。明确黄土地区植物对气候因子变化的适应机制,为该地区植被配置提供理论依据。

关键词: 水分利用效率, 稳定碳同位素, 可溶性糖, 黄土地区, 混合线性模型

Abstract: Aims This article explored the short-term water use efficiency of typical trees and shrubs in the loess area of western Shanxi with environmental factors. Our objective was to clarify the water use pattern and adapt strategies of plants in this area. It is beneficial to improving the efficiency of vegetation construction in the loess area. Methods In this study, we used typical trees (Pinus tabuliformis and Robinia pseudoacacia) and typical understory shrubs (Rosa xanthina and Periploca sepium) as the research species. The stable carbon isotope of soluble sugars(δ13Cleaf) in plant leaves and phloem of branches(δ13Cbarnch) were measured. δ13Cleaf was used to calculated the change trend of the plant's short-term water use efficiency (WUEleaf) at the leaf scale. We compared the difference of WUEleaf between typical species and determined WUEleaf’s response to changes of environmental factors. Important findings The results showed that: (1) During the observation period, the δ13Cleaf of the four plant showed an overall decreasing trend, and δ13Cbranch showed a trend of first increasing and then decreasing. There are differences in δ13Cleaf between species and life forms. The specific performance is: shrubs>trees, evergreen trees (Pinus tabuliformis)>deciduous trees (Robinia pseudoacacia). (2) During the observation period, the WUEleaf value of the four plants remained stable first, and then increased rapidly. When Ta>25℃ or VPD>1.0kPa, the life type caused the difference in WUEleaf value among the four plants, which was specifically expressed as: Periploca sepium > Rosa xanthina > Pinus tabuliformis >Robinia pseudoacacia. Otherwise, environmental factors are the main factors affecting the changes of WUEleaf of trees and shrubs. The specific performance is: Periploca sepium>Robinia pseudoacacia>Rosa xanthina> Pinus tabuliformis. (3) The WUEleaf value gradually decreases with the increase of Ta, RH, and VPD, and there is a quadratic relationship with SWC. Ta changes the photosynthetic rate through non-stomatal factors. The action of enzymes caused changes in the WUEleaf value. The moisture factor affects transpiration by changing the stomata opening, and then changes the WUEleaf value. With the increase of SWC, the value of WUEleaf showed a trend of first increasing and then decreasing. The WUEleaf reached the highest value when the SWC reached 15%-18% and 13%-14% in Pinus tabuliformis forest and Robinia pseudoacacia forest. The dominant environmental factors of different plants WUEleaf are also different. After LMM analysis, the dominant environmental factors of Pinus tabuliformis and Robinia pseudoacacia are RH and VPD, respectively. However, Ta is the dominant environmental factor of Periploca sepium and Rosa xanthina. Through this study, we can quantify the water use ability of typical trees and shrubs in the loess area, the internal water consumption mechanism in the growing season and the main environmental impact factors. This study provides a theoretical basis for the vegetation configuration in this area.

Key words: water use efficiency, stable carbon isotope, soluble sugar, the loess area, linear mixed model