Water use efficiency of China's karst ecosystems: The effect of different ecohydrological and climatic factors

Xu Zhou; Yang Ao; Xiao Jiang; Shengtian Yang; Yuxue Hu; Xiaohua Wang; Ji Zhang

doi:10.1016/j.scitotenv.2023.167069

Water use efficiency of China's karst ecosystems: The effect of different ecohydrological and climatic factors

Sci Total Environ. 2023 Dec 20:905:167069. doi: 10.1016/j.scitotenv.2023.167069. Epub 2023 Sep 14.

Authors

Xu Zhou¹, Yang Ao², Xiao Jiang³, Shengtian Yang⁴, Yuxue Hu², Xiaohua Wang⁵, Ji Zhang⁶

Affiliations

¹ School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China. Electronic address: zhouxu@gznu.edu.cn.
² School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China.
³ School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China; State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
⁴ School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China; College of Water Sciences, Beijing Normal University, Beijing 100875, China.
⁵ PIESAT Information Technology Co., Ltd., Beijing 100195, China.
⁶ School of Geography and Environmental Sciences, Guizhou Normal University, Guiyang 550025, China; Chongqing Institute of Meteorological Sciences, Chongqing 401147, China.

PMID: 37714359
DOI: 10.1016/j.scitotenv.2023.167069

Abstract

Water use efficiency (WUE) is an important indicator for understanding the coupled ecosystem carbon and water cycles. However, the effect and contributions of factors on WUE variations in China's karst ecosystems for different climatic conditions have not been extensively studied. Our studies on WUE variations of China's karst ecosystems from 2001 to 2021 based on evapotranspiration and net primary productivity (NPP) from Moderate-resolution imaging spectroradiometer revealed the contributions of soil moisture (SM), leaf area index (LAI), precipitation (P), temperature (T), vapor pressure deficit (VPD), and CO₂ concentration (CO₂). Results showed that the trend of WUE was similar to that of NPP in terms of the latitude, longitude, and elevation, and WUE started abruptly decreasing after an elevation >3000 m until it reached 0 at 4500 m. WUE was primarily "slightly increased" in the humid region (H) and "slightly decreased" in the semi-humid region (SH), arid and semi-arid regions (ASA), and Qinghai-Tibet plateau region (QTP). CO₂ (0.34), LAI (0.60), P (0.58), and LAI (0.55) exhibited the strongest positive direct effects on WUE in H, SH, ASA, and QTP, while VPD exhibited the strongest negative direct effect. VPD (0.26), VPD (0.28), SM (0.47), and P (0.39) had the strongest positive indirect effect, while T (-0.24), T (-0.18), VPD (-0.35), and P (-0.03) had the strongest negative indirect effect on WUE. The positive contributions of WUE variations in H, SH, ASA, and QTP were dominated by T (47.96 %), CO₂ (26.36 %), P (8.81 %), and CO₂ (52.97 %), whereas the negative contributions were dominated by P (-7.95 %), LAI (-26.57 %), CO₂ (-35.98 %), and VPD (-9.59 %), respectively. This study quantifies the spatial and temporal distribution patterns of WUE in China's karst ecosystems and the regional differences between the multiple ecohydrological factors, thereby facilitating in-depth understanding and effective regulation for the carbon and water cycles in karst ecosystems.

Keywords: Different climatic conditions; Ecohydrological factors; Elasticity coefficient analysis; Karst ecosystem; Path analysis; Water use efficiency.