Assessing the carbon-water compound use efficiency in fragile karst region: The Yunnan-Guizhou Plateau, China

Abstract

In karst regions, water scarcity often challenges vegetation’s carbon balance. While carbon and water use efficiencies (CUE and WUE) are crucial metrics, traditional assessments lack a comprehensive evaluation of their combined impact. This study bridged this gap by introducing carbon–water compound use efficiency (COM) and investigating its key drivers in the Yunnan-Guizhou Plateau using exploratory spatial analyses to identify the scale effect of spatial divergence of COM, and then explored the driving forces of COM from natural and human factors at optimal scale using the optimal parameter geo-detector (OPGD) and geographically weighted regression (GWR) model. The findings revealed that (1) Between 2000 and 2018, the mean CUE in the Yunnan-Guizhou Plateau karst regions exceeded that of non-karst areas, while the mean WUE and COM were lower in the karst areas compared to non-karst areas. (2) except for CUE, the WUE and COM tended to increase, and the change rates were greater in the karst areas; (3) NDVI dominated the spatial divergence of COM, showed a shift from a negative correlation in the eastern to a positive correlation in the western of the study area. These findings shed light on the unique dynamics of CUE and WUE in karst landscapes, providing valuable insights for targeted ecological restoration projects and promoting a sustainable balance between carbon and water resources.

Keywords

• Carbon and water processes
• Scale effect
• Spatial autocorrelation
• Driving mechanisms