沿黄丘陵沟壑区水土保持生态空间分布特征及时空演化——以山西省柳林县为例

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

黄河中游是黄土高原地区土壤侵蚀的核心区域,水土流失问题严重,加强中游水土保持工作对于推动黄河流域生态保护和实现高质量发展至关重要。本文选择沿黄河中游丘陵沟壑区典型县域——山西省柳林县为研究区,基于水源涵养空间、土壤保持空间及水土流失敏感性识别和分级,对水土保持生态空间进行划定分区,并采用冷热点分析、标准差椭圆的方法揭示研究区水土保持生态空间的分布特征,并分析其2000—2020年时空演化特征。结果表明:1)柳林县水源涵养空间的功能等级总体呈由北向南逐渐降低的趋势,高等级面积占研究区总面积的35.2%;土壤保持强度以低等级为主,集中分布在研究区的西部及中部。2)2000—2020年柳林县水土流失高度敏感区占比一直在40%以上且面积持续增加,不敏感区、轻度敏感区及中度敏感区面积持续减少。3)柳林县水土保持生态空间分布整体呈南—北走向,无成片连续分布,主要集中在丘陵沟壑区的沟间区域,其中重点区与核心区交错分布在沟道陡坡区,一般区主要分布在河流或沟道沿岸坡度较缓的区域。4)2000—2020年,核心区面积一直呈减小趋势,一般区、重点区及核心区的标准差椭圆重心均向西南方向移动,以向南移动为主。柳林县的水土保持生态空间识别与时空演变趋势研究结果可为其水土保持的差别化治理提供参考,有效保持水土资源,推动黄河流域生态保护与高质量发展。

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 ecolo-gical spatial extent of soil and water conservation,distribution patterns,and their changes remain unclear,limiting the effective imple-mentation 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 wa-ter 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 wa-ter conservation space in Liulin County showed a general trend of gradual decrease from north to south,with the high-grade area ac-counting 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 moder-ately 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 gener-al 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 decreas-ing 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.