环境与林分特征因子对桉树人工林水分利用效率的影响机制OA

[Objective]In the context of global warming,this study systematically investigated the mechan-isms by which environmental factors,including climate type,temperature,precipitation,altitude,and soil properties,and stand characteristic factors,including stand age,tree height,diameter at breast height,and stand density,influence the water use efficiency(WUE)of Eucalyptus.[Methods]A total of 289 observa-tional data from 36 studies worldwide were analyzed.Environmental factors were divided into subgroups,and differences in WUE among subgroups were examined using the Wilcoxon rank-sum test combined with multiple comparison methods.Random forest analysis and structure equation modelling were further employed to identify the key factors affecting Eucalyptus WUE and to elucidate their mechanisms.[Results]Eucalyptus plantations in semi-arid and semi-humid regions exhibited higher WUE than those in humid and arid regions.The highest WUE was observed when soil pH ranged from 6.0 to 6.7,mean annu-al precipitation ranged from 1 210 to 1 400 mm,and mean annual temperature ranged from 22.0 to 23.5℃.Among soil factors,total soil potassium was the most influential factor affecting WUE.Relatively high WUE was also associated with young stands and stand densities of approximately 2 150 trees per hectare.[Conclusions]The WUE of Eucalyptus plantations is jointly regulated by environmental conditions and stand characteristics.Optimizing stand structure,particularly stand age and stand density,can signific-antly enhance WUE.This study reveals the response patterns of Eucalyptus WUE to hydrothermal gradi-ents and soil nutrients,providing scientific guidance for water management,stand structure optimization,and sustainable plantation management.