亚热带季风区典型土壤-植物-大气连续体中水体平均滞留时间  

Mean transit time of water bodies in a typical soil-plant-atmosphere continuum of the subtropical monsoon region

作　　者：李嘉洁 章新平[1] 肖雄[1] 张赐成[1] 王锐[1] 戴军杰 罗紫东 刘娜 LI Jiajie;ZHANG Xinping;XIAO Xiong;ZHANG Cicheng;WANG Rui;DAI Junjie;LUO Zidong;LIU Na(School of Geographical Science,Hunan Normal University,Changsha 410081,China;Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,China;College of Geography and Tourism,Hengyang Normal University,Hengyang 421002,Hunan,China)

机构地区：[1]湖南师范大学地理科学学院,长沙410081 [2]中国科学院亚热带农业生态研究所,长沙410125 [3]衡阳师范学院地理与旅游学院,湖南衡阳421002

出　　处：《应用生态学报》2023年第12期3184-3194,共11页Chinese Journal of Applied Ecology

基　　金：湖南省自然科学基金青年项目(2022JJ40274,2023JJ40445);国家自然科学基金青年科学基金项目(42101130)资助。

摘　　要：平均滞留时间(MTT)在水循环过程中具有重要的指示意义,但目前对亚热带季风区典型土壤-植物-大气连续体(SPAC)中不同水体的MTT仍缺乏了解。本研究以长沙市郊区的樟树林为研究对象,基于稳定同位素技术并利用线性混合模型和正弦波拟合法计算2017年3月—2019年10月不同深度土壤水、枝条水和叶片水的MTT。结果表明:SPAC中不同水体稳定同位素呈现夏季贫化、冬季富集的季节变化模式;土壤水δ^(2)H随深度增加而偏负,枝条水δ^(2)H与土壤水接近,但叶片水δ^(2)H偏正且变化范围较大。线性混合模型显示,土壤水和植物水MTT的较低值出现在6—9月,较高值常出现在1月前后和4—5月;降水补给比例与MTT呈显著的负相关关系,大多数时段土壤水MTT随深度增加而增加,但优先流也可增加深层土壤水的补给比例,从而降低MTT;枝条水和叶片水的MTT平均值接近。正弦波拟合法显示,随土壤深度增加,土壤水新水比例(F_(yw))逐渐降低,而MTT逐渐增加;枝条水的F_(yw)和MTT分别低于和高于叶片水。线性混合模型与正弦波拟合法的土壤水MTT均自表层向深层增加,其中,前者的变化范围较小,后者的变化范围较大;线性混合模型中枝条水MTT比叶片水少2.4 d,而正弦波拟合法中枝条水MTT比叶片水多87.4 d。两种模型模拟结果的差异可能与“新水”的定义、结果不确定性和蒸发分馏效应等有关。本研究结果将有助于理解亚热带季风区SPAC水分运移与消耗过程,并可为农业生产和水资源管理提供理论依据。The mean transit time(MTT) is a good indicator of water cycle processes. We know little about the MTT of different water bodies within the soil-plant-atmosphere continuum(SPAC) in the subtropical monsoon region. We estimated the MTT of stratified soil water at different depths as well as the xylem water and leaf water in typical Cinnamomum camphora woodland located in Changsha City from March 2017 to October 2019. The main methods used in this study included the stable isotope technology, the linear mixed model and the sine wave fitting method. The results showed that the stable isotopes were more depleted in summer and enriched in winter for different water bodies within the SPAC. The δ^(2)H values of soil water gradually decreased as depth increased. The δ^(2)H values of xylem water closely resembled those of soil water, but the δ^(2)H values of leaf water were more positive and exhibited larger variation. Results of the linear mixed model indicated that the lower MTT values of soil water and plant water occurred between June and September, while the higher values were often observed around January and from April to May. The precipitation replenishment exhibited a significant negative correlation with the MTT. The MTT of soil water generally increased with depth, although preferential flow could enhance the replenishment of deeper soil water and subsequently reduce the MTT. The mean MTT values of xylem water and leaf water were similar. Results of the sine wave fitting method showed that the young water fraction(F_(yw)) of soil water gradually decreased as depth increased, while the MTT of soil water gradually increased as depth increased. The F_(yw) and MTT of xylem water were lower and higher than those of leaf water, respectively. Both the mean MTT values of soil water based on the linear mixed model or the sine wave fitting method increased from the surface to the deeper soil layers. The former exhibited a smaller variation range and the latter showed a larger variation range. The mean MTT value of xylem

关 键 词：土壤-植物-大气连续体 稳定同位素 平均滞留时间 新水比例 降水补给比例 

分 类 号：Q948.113[生物学—植物学]