Partitioning tree water usage into storage and transpiration in a mixed forest  

作　　者：Ziqiang Liu Qianqian Liu Zijun Wei Xinxiao Yu Guodong Jia Jiang Jiang 

机构地区：[1]Co-Innovation Center for Sustainable Forestry in Southern China,Nanjing Forestry University,Nanjing 210037,China [2]Key Laboratory of Soil and Water Conservation and Desertification Combating of Ministry of Education,Beijing Forestry University,Beijing 100083,China

出　　处：《Forest Ecosystems》2021年第4期961-973,共13页森林生态系统（英文版）

基　　金：funded by the National Natural Science Foundation of China(No.42007182);the self made experimental teaching instruments of Nanjing Forestry University in 2021(nlzzyq202127).

摘　　要：Background:Water migration and use are important processes in trees.However,it is possible to overestimate transpiration by equating the water absorbed through the plant roots to that diffused back to the atmosphere through stomatal transpiration.Therefore,it is necessary to quantify the water transpired and stored in plants.Method:The δ^(2)H/δ^(18)O technique and heat ratio method were used to explore the water usage of coniferous and broad-leaved tree species,including the proportions of water used for transpiration and water storage.Results:Platycladus orientalis and Quercus variabilis had strong plasticity in their water usage from different sources.Platycladus orientalis primarily used groundwater(30.5%)and the 60-100-cm soil layer(21.6%)throughout the experimental period and was sensitive to precipitation,absorbing water from the 0-20-cm layer(26.6%)during the rainy season.Quercus variabilis absorbed water from all sources(15.7%-36.5%)except from the 40-60-cm soil layer during the dry season.In addition,it did not change its water source but increased its groundwater uptake during the rainy season.The annual mean water fluxes of P.orientalis and Q.variabilis were 374.69 and 469.50 mm·year−1,with 93.49% and 93.91% of the water used for transpiration,respectively.However,nocturnal sap flow in P.orientalis and Q.variabilis was mainly used for water storage in the trunk rather than transpiration,which effectively alleviated drought stress and facilitated the transport of nutrients.Conclusions:The water stored in both species comprised 6%-7% of the total water fluxes and,therefore,should be considered in water balance models.

关 键 词：Water migration Water uptake Nocturnal sap flow TRANSPIRATION 

分 类 号：S718.3[农业科学—林学]