Distribution characteristics and spatiotemporal evolution of soil and water conservation ecological spaces in the hilly and gully areas along the Yellow River: A case study of Liulin County, Shanxi Province

Enhancing soil and water conservation efforts is crucial to addressing soil erosion in the middle reaches of the Yellow River Basin; this is pivotal for ecological preservation and the pursuit of high-quality development in the region. However, the ecological spatial extent of soil and water conservation, distribution patterns, and their changes remain unclear, limiting the effective implementation of differentiated prevention and protection measures. In this study, Liulin County, which is situated along the middle reaches of the Yellow River and represents a typical county in a region characterized by hills and gullies, was selected as the study area. The soil and water conservation ecological space was demarcated and partitioned based on the identification and grading of water source conservation space, soil conservation space, and erosion sensitivity. Cold-hot spot analysis and standard deviation ellipses were used to reveal the distribution characteristics of the soil and water conservation ecological space in the study area. The spatial and temporal evolution characteristics from 2000 to 2020 were analyzed. The results showed that: 1) The functional grade of the water conservation space in Liulin County showed a general trend of gradual decrease from north to south, with the high-grade area accounting for 35.2% of the total study area. The intensity of soil retention was dominated by the low-grade area, which was centrally distributed in the western and central parts of the study area. 2) From 2000 to 2020, the percentage of highly sensitive erosion areas in Liulin County has been above 40%, and the area has continued to increase, while the area of insensitive, mildly sensitive, and moderately sensitive areas have continued to decrease. 3) The distribution of soil and water conservation ecological space in Liulin County as a whole was in the south-north direction; there was no piecemeal continuous distribution, mainly concentrated in the inter-ditch area of the hilly and gully area, of which the key area and the core area were staggered in the steep slope area of the ditch. The general area was mainly distributed along the slopes of the river or ditch. 4) From 2000 to 2020, the size of the core area showed a decreasing trend, and the centers of gravity of the standard deviation ellipse for the general area, the focus area, and the core area all shifted to the southwest, predominantly to the south. The results of the study on the identification of soil and water conservation ecological space and the trend of spatial and temporal evolution in Liulin County can provide a reference for the differentiated management of soil and water conservation in Liulin County to effectively maintain soil and water resources and promote ecological protection and high-quality development of the Yellow River Basin.