Multiscale analysis framework for assessing land degradation neutrality with ecosystem services: A case study of the Yellow River basin

As a component of sustainable development goals, Land Degradation Neutrality (LDN) is an overarching tool to curb global land degradation. Since LDN requires realization at a specific spatiotemporal scale, how to bridge the pixel-scale degraded area and the regional-scale LDN unrealized area needs further study. Thus, a multiscale analysis framework for LDN was constructed, with the Yellow River Basin (YRB) in China as a case study and 2000–2020 as the study period. Concretely, the land types were divided into land for ecosystem function and services (LEFS) and land for food security (LFS) by combining the concepts and the "like for like" principle. Then, an attempt was made to replace or supplement the original LDN indicators with some of the ecosystem service indicators, which were then divided into dominant and recessive indicators. Finally, the LDN assessment was conducted at "basin-provincial-city-county" multiscale and at pixel scale following the "one out-all out" principle. The following results were obtained: (1) at the pixel scale, the improved areas of both LEFS and LFS were greater than the degraded areas. However, the degraded LEFS remained severe in sporadic areas, while the degraded LFS was mostly concentrated around the built-up areas of large cities. (2) At the regional scale, positive outcomes in LEFS conservation were achieved in the YRB in the last 20a. However, LDN remained unachieved on the watershed scale due to insufficient efforts toward LFS. Besides, very few districts achieved LDN on the "provincial-city-county" scale. (3) The LDN should be integrated into land-use planning to establish a progressive system at the multiscale level, which could articulate between physical geography and administrative districts. Furthermore, differentiated protection and rehabilitation solutions were applied to LEFS and LFS, following the "Avoid > Reduce > Reverse" principle. (4) The degradation of the LEFS and LFS caused by large-scale construction was almost inevitable during the extensive economic growth phase. Therefore, future promotion of LDN ought to follow the "common but differentiated principle" and consider differentiated base times tailored to economic development levels. Overall, this study provided a new tool for LDN assessment efficiently and conveniently, thus making a marginal contribution to global action for curbing land degradation.