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应用生态学报 ›› 2020, Vol. 31 ›› Issue (3): 829-836.doi: 10.13287/j.1001-9332.202003.023

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土壤水分对黄土区苹果园土壤-植物-大气连续体(SPAC)中水势梯度的影响

党宏忠1*, 却晓娥1, 冯金超1, 王檬檬2, 陈帅1   

  1. 1中国林业科学研究院荒漠化研究所, 北京 100091;
    2内蒙古农业大学沙漠治理学院, 呼和浩特 010018
  • 收稿日期:2019-06-17 出版日期:2020-03-15 发布日期:2020-03-15
  • 通讯作者: E-mail: hzdang@caf.ac.cn
  • 作者简介:党宏忠, 男, 1971年生, 副研究员。主要从事生态水文研究. E-mail: hzdang@caf.ac.cn
  • 基金资助:
    本文由国家重点研发计划项目(2016YFC0501704)资助

Effect of soil moisture on water potential gradients in the soil-plant-atmosphere continuum (SPAC) of apple orchards in the Loess Plateau, Northwest China

DANG Hong-zhong1*, QUE Xiao-e1, FENG Jin-chao1, WANG Meng-meng2, CHEN Shuai1   

  1. 1Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China;
    2College of Desert Control Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China
  • Received:2019-06-17 Online:2020-03-15 Published:2020-03-15
  • Contact: E-mail: hzdang@caf.ac.cn
  • Supported by:
    This work was supported by the National Key R&D Program of China (2016YFC0501704)

摘要: 开展土壤-植物-大气连续体(SPAC)中水势变化的联动分析对于揭示植物水分状况对环境变化的响应机制有重要意义。在黄土高原苹果园对果树生长季大气水势(Ψair)、木质部水势(Ψstem)、土壤水势(Ψsoil)进行连续监测与分析。结果表明: 苹果树在生长季的日平均Ψstem为-0.57 MPa,在-0.24~-2.0 MPa间变化。苹果树SPAC连续体中水势梯度(ΨsoilΨstemΨair)平均为1∶9.8∶1155,其中植-土界面的水势梯度(ΨstemΨsoil)与土壤体积含水率(VWC)间呈极显著的线性正相关关系,ΨstemΨsoil间呈良好的线性关系,且相关性强于ΨstemΨair间的相关性。当Ψsoil<-0.08 MPa(VWC=17%,约为田间持水量的0.56倍)时,ΨstemΨsoil变化响应的敏感性明显降低,气-植界面的水势梯度(ΨairΨstem)与Ψsoil间由无明显关系转变为紧密的线性相关关系(R2=0.93)。ΨairΨstem的驱动存在阈值效应,在Ψair降到-69 MPa前,Ψstem日变化幅度随Ψair增加而增加,之后呈下降趋势。土壤含水率降低引起苹果树水势、SPAC各界面上的水势梯度明显下降,且在土壤含水率降至约17%时存在阈值效应。研究结果为理解树木水分状况对土壤、大气干旱的响应机制提供了重要依据。

Abstract: The variations of water potential gradients through the soil-plant-atmosphere continuum (SPAC) are of great significance to reveal the responses of plant water use to environmental changes. We conducted a continuous experiment to monitor the potentials in the near-canopy atmosphere (Ψair), soil (Ψsoil) and plant xylems (Ψstem) during the growing season in an apple orchard located in the Loess Plateau. The results showed that the average Ψstem during the growing season ranged from -0.24 to -2.0 MPa, with a mean value of -0.57 MPa. The average water potential gradient in soil-plant-atmosphere system was 1:9.8:1155 (Ψsoil:Ψstem:Ψair). We found a significant positive linear correlation between the Ψstem:Ψsoil gradient and volumetric soil water content (VWC, %). The Ψstem was more strongly correlated with Ψsoil than Ψair. Moreover, the sensitivity of Ψstem to Ψsoil decreased when Ψsoil was lower than -0.08 MPa which corresponded to VWC=17%, 0.56 times of field capacity. This was reflected by the increased linearity between Ψair /Ψstem and Ψsoil as Ψsoil decreased. There was a threshold effect for the relationship between Ψair and Ψstem. That is, the Ψstem in a day increased with the increasing of Ψair before the latter reached -69 MPa, after which the Ψstem decreased. The decline of soil water content caused an obvious decrease in water potential gradient through the SPAC system, and the threshold effect existed when VWC was below 17%. The results provide a basis for understanding the mechanisms of plant water in response to soil and atmospheric drought.