Water use strategies determine divergent growth trends of spruce and juniper on the southeastern Tibetan plateau  

作　　者：Lu Wang Hongyan Liu Liang Shi Xianliang Zhang Boyi Liang Ru Huang Jussi Grießinger Steven Leavitt Yuemin Yue Kelin Wang 

机构地区：[1]Key Laboratory for Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha,410125,China [2]College of Urban and Environmental Sciences,Peking University,Beijing,100871,China [3]Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing,100101,China [4]College of Forestry,Hebei Agricultural University,Baoding,071001,China [5]College of Forestry,Precision Forestry Key Laboratory of Beijing,Beijing Forestry University,Beijing,100083,China [6]National Institute of Natural Hazards,Beijing,100085,China [7]Friedrich-Alexander-University Erlangen-Nürnberg,Institute of Geography,Wetterkreuz,Erlangen,Germany [8]Laboratory of Tree-Ring Research,University of Arizona,Tucson,AZ,USA

出　　处：《Forest Ecosystems》2024年第6期951-959,共9页森林生态系统(英文版)

基　　金：funded by the National Natural Science Foundation of China(No.42161144008).

摘　　要：Warming and increased CO_(2)levels are generally believed to enhance photosynthetic rates(A)and tree growth,especially in alpine treelines.However,this positive effect may be limited by moisture availability.Here we compare the radial growth and intrinsic water use efficiency(iWUE)of two widely-distributed evergreen needleleaf species,Tibetan juniper(Juniperus tibetica)and Balfour spruce(Picea balfouriana),at the same site near the treeline on the southeastern Tibetan Plateau using tree-ring width and dual isotopes(δ^(13)C andδ^(18)O).We observed that with a 70-ppm increase in atmospheric CO_(2)from 1954 to 2007,juniper radial growth was significantly stimulated,whereas spruce growth remained constant.Correlation analysis between tree-ring width and climate factors revealed that spruce was more moisture-sensitive than juniper.Although the increases in iWUE for juniper(22%)and spruce(26%)were similar,iWUE changes in spruce were more influenced by stomatal conductance(gs)rather than A,supporting that moisture availability inhibits spruce growth.Our study implies that predicting growth dynamics in alpine forests based on the growth-temperature relationship may be inadequate,as they are likely moisture-limited.It also suggests that increases in A may not be as widespread as previously thought,which helps improve forest productivity modeling.

关 键 词：Tree rings Climate changes Intrinsic water-use efficiency(iWUE) Dual-isotope approach Tibetan plateau 

分 类 号：F41[经济管理—产业经济]