Comprehensive management method of "Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts" composite system for Three-North Region sandy lands based on coordination degree of composite systems and windscape division.

Desertification is one of the most critical challenges worldwide. Ecological restoration is one of the effective ways to control desertification. Due to the complexity of the desertification process and ecological fragility, the prevention and controlling of desertification are difficult to achieve stable and sustainable effects by relying solely on vegetation restoration. In this study, desertification areas were considered as "Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts" composite system from the perspective of the principle of harmony of composite systems. We proposed a new framework to achieve the goal of coordinated sustainable development of ecology-production-living function of sandy land composite ecosystem with the Coordination Degree of Composite Systems (CDoCS) as the key indicator. The sandy land within the region of Three-North Afforestation Program (TNAP, covering 96.5% of the country's sandy areas) was selected as the study area, including sand land, deserts, as well as the areas undergoing desertification and potential desertification (2.34×10⁶ km², covering 52.1% of TNAP). Based on the concept of windscape, we delineated the applicability scope for the application of CDoCS framework that covered the sand land of TNAP, including three levels from large to small: first-level windscapes (28), second-level windscapes (169), and third-level windscapes (1686). The three levels of windscapes were suitable for the management at different scales, which were the minimum unit for the application of the CDoCS framework. We applied the framework in the third-level windscapes, with Wengniute Banner, a typical sandy area, as an example. The CDoCS of Wengniute Banner was improved from 0.578 to 0.656, transferring from a medium coordinated state to a state close to a high coordinated state. The methodology framework proposed here was a promising approach to achieve the comprehensive management of "Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts" composite system and integrated desertification control.