Influence of the ecosystem conversion process on the carbon and water cycles in different regions of China

Ecosystem conversion processes in different regions of China have different impacts on carbon and water cycle changes. Water use efficiency (WUE) is a key factor in coupling ecosystem carbon and water cycles, and it is important to quantify the effects of ecosystem conversional processes on the WUE in different regions of China to improve our understanding of the effects of ecological restoration projects and ecosystem conversional processes on carbon and water cycles in different regions. In this study, we proposed a dual-type extraction algorithm for ecosystem conversion processes (DTEA-ECP) to study the impact of ecosystem conversion processes on the WUE in different regions of China from 2001 to 2020. Our results showed that in the 2001-2020 period, the area of barren ecosystem conversion to grassland ecosystem increased at the fastest rate (4.29*103 km2 y-1). In the snow climate zone with dry winters and warm summers, projects returning cropland to forest were beneficial for improving WUE. In the northwestern part of the semiarid climate zone, returning cropland to grassland was beneficial for increasing the WUE of the ecosystem, while in northeastern China, the change in WUE after the conversion of grassland ecosystem to cropland ecosystem was not significant. WUE decreased after the con -version of forest ecosystems to grassland ecosystems, while WUE increased after the conversion of grassland ecosystems to forest ecosystems. This study identified where it was most suitable to plant each vegetation type and can help with the implementation of ecological projects such as afforestation, returning farmland to forest and grass, grassland protection and wind and sand management. The results provide information support for the in-depth development of national greening and low-carbon land restoration, improve vegetation carbon sink capacity, enhance carbon emission reduction and carbon sequestration, and help to achieve the goal of peak carbon and carbon neutrality.