Life form and behavior type shape water use efficiency in tropical plants via leaf functional traits

作者：J. Y. Chen, Tianbao Ren, Heng Xie, Wanxin Yang, Weirong Zhang, Jinling Zhang, Mingze Xu, Liucui Wu, Zehao Fan, Cheng Yi, Shanxia She, Zhongmin Hu, Chuan Jin · 发表于：Environmental and Experimental Botany · 年份：2026 · DOI：10.1016/j.envexpbot.2026.106315 · 被引用次数：3 · 研究领域：Plant Water Relations and Carbon Dynamics、Remote Sensing in Agriculture、Plant responses to water stress

Understanding how water use efficiency ( WUE ) responds to fluctuating light is critical for predicting ecosystem function under global change. In this study, we examined photosynthetic gas exchange and leaf functional traits across 48 tropical plant species in Hainan, categorized by life form (woody/herbaceous) and light-adaptation (sun/shade). We introduced a novel suite of parameters [e.g., maximum WUE ( WUE max ), rising slope ( R S ), and declining slope ( D S )] to quantify the dynamic WUE -light response curve. Our results revealed divergent water-use strategies where elevated CO 2 enhanced WUE max in shade-tolerant species but reduced it in sun-adapted species. This negative reaction might be caused by the closure of stomata in sun-adapted plants, and its inhibitory effect on photosynthesis is stronger than that on transpiration. Using EXtreme Gradient Boosting model, we identified mean tilt angle (MTA) and leaf nitrogen content (LNC) as direct regulators of WUE max . SHapley Additive exPlanation analysis further indicated this was a non-linear relationship, where moderate leaf inclination was associated with improved WUE max . We further uncovered a key physiological trade-off where WUE max was positively associated with mesophyll conductance ( g m ) but negatively correlated with stomatal conductance ( g s ) and photosynthetic capacity. This is because high g m ensures efficient CO 2 diffusion to carboxylation sites, whereas excessively high g s leads to substantial...