Assessing spatiotemporal dynamics of water use efficiency in ecologically vulnerable karst landscapes

Southwest China Water use efficiency (WUE) is a key variable for understanding the carbon and water cycling processes in ecosystems. There exists the world's largest continuous karst topography in Southwest China, rendering it a quintessential ecologically vulnerable region. Therefore, determining the trends in WUE changes between karst and non-karst ecosystems is of great significance for understanding the carbon and water cycling processes in ecologically vulnerable areas. In this study, various analysis methods were utilized to explore the spatiotemporal variations, persistence characteristics, and the impact of complex climatic variability of WUE in Southwest China. (i) The rate of increase and multi-year average of WUE in karst ecosystem is higher than that in non-karst ecosystem. (ii) In the future, the proportion of area with decreasing in WUE will be higher in karst ecosystem than in non-karst ecosystem. (iii) There are significant differences in the correlation between WUE and climatic factors in different ecosystems. (iv) The dominant climatic factor for WUE in karst ecosystem is vapor pressure, while in non-karst ecosystem, it is precipitation. The research results can provide a theoretical basis for studying the carbon and water cycling processes in karst ecosystem.