“…This study investigated the impact of latitude, elevation, SM, and four meteorological variables (PRE, TEM, PDSI, and VPD) on WUE. It is worth noting that WUE can also be influenced by additional factors, such as rising atmospheric CO 2 (Battipaglia et al., 2020; Law, 2013; N. Liu et al., 2020; X. Liu et al., 2020), nitrogen deposition (Adams et al., 2021; Gharun et al., 2021; Law, 2013; X. Lu et al., 2019), solar radiation (H. Zheng et al., 2019; P. F. Zheng et al., 2019), nutrient cycling (Ding et al., 2022; Keenan et al., 2013; Morecroft et al., 1992), and change in land use (Guo et al., 2019; H. Sun et al., 2022). Previous research has demonstrated that CO 2 concentration can affect WUE by influencing plant physiology and stomatal conductance (L. He et al., 2017; X. Liang et al., 2023; Umair et al., 2020; Zhu et al., 2011).…”