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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

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

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.