文献类型：期刊文献

英文题名：Biophysical controls on water use efficiency of six plantations under different sky conditions

作者：Liu, Peirong[1] Tong, Xiaojuan[1] Meng, Ping[2] Zhang, Jinsong[2] Li, Jun[3] Zhang, Jingru[1] Zhou, Yu[2]

第一作者：Liu, Peirong

通信作者：Tong, XJ[1]

机构：[1]Beijing Forestry Univ, Sch Ecol & Nat Conservat, Beijing 100083, Peoples R China;[2]Chinese Acad Forestry, Res Inst Forestry, Key Lab Tree Breeding & Cultivat State Forestry A, Beijing 100091, Peoples R China;[3]Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Water Cycle & Related Land Surface Proc, Beijing 100101, Peoples R China

年份：2022

卷号：320

外文期刊名：AGRICULTURAL AND FOREST METEOROLOGY

收录：;Scopus(收录号：2-s2.0-85128975238);WOS:【SCI-EXPANDED(收录号:WOS:000795700800003)】；

基金：Acknowledgments This study was sponsored by the National Nonprofit Institute Research Grant of the Chinese Academy of Forestry (CAFYBB2018ZA001) and the National Natural Science Foundation of China (31872703; 31570617) .

语种：英文

外文关键词：Water use efficiency; Diffuse fraction; Canopy conductance; Plantation

摘要：Ecosystem water use efficiency (WUE) is an indicator characterizing carbon-water coupling of the terrestrial ecosystems. The increasing diffuse radiation enhances carbon assimilation. However, the impact of diffuse radiation interacting with biophysical factors on WUE is still not well-understood. Based on carbon and water vapor fluxes measured by the eddy covariance systems during 2019-2020, we explored the effects of biophysical factors on WUE under different sky conditions at 6 plantation ecosystems (2 deciduous broad-leaved and 4 coniferous plantations) in eastern China. WUE on cloudy days was 4.5-21.5% higher than that on clear days at 6 sites, which was attributed to the increase in ecosystem carbon gain and reduction in water loss. Diffuse fraction (DF) exerted significantly positive direct effects on WUE at JZ, MQ, JY and SHB sites (p < 0.05), with the path coefficients of 0.30-0.58. However, it had positive indirect effects on WUE at HS1 and HS2 sites by altering photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and canopy conductance (gc). WUE was primarily regulated by VPD and gc, and the path coefficients of the direct effect were -0.34--0.73 and -0.33- 0.73, respectively. The indirect effect of VPD on WUE through stomatal behavior was remarkable. Compared with the normal year, the regulation of DF on WUE was less in the dry year. For subtropical evergreen coniferous and warm-temperate deciduous broad-leaved plantations, WUE of the dry year was higher than that of the normal year. Warm-temperate deciduous broad-leaved plantations avoided drought by reducing gc to remain conservative water-use strategy, whereas the subtropical evergreen coniferous plantation kept high gc to obtain lower WUE in the dry year. These findings will contribute to understand the influence of diffuse radiation on the coupling between carbon and water vapor fluxes.