中国北方农牧交错带生态格局演变与优化及修复调控策略OA

As a critical ecological security barrier and key production base in northern China,the agro-pastoral ecotone features a fragile ecological environment and holds a unique strategic position.The evolution and optimal regulation of its ecological pattern are crucial for regional sustainable development.Based on land cover data,meteorological observations,remote sensing retrievals,and socioeconomic data,this study systematically investigated the evolutionary patterns and driving mechanisms of the regional ecological pattern and constructed an optimization system and restoration strategies by integrating methods such as ecosystem distribution pattern analysis and the minimum cumulative resistance model,combined with the natural-artificial dualistic water cycle theory.The results indicate that from 1990 to 2023,the ecological pattern of the northern agro-pastoral ecotone exhibits significant spatiotemporal differentiation.Ecologically improved areas generally shift northeastward towards humid regions and are contracted in the southwestern arid regions.Forests are concentrated in the northeast,while farmland and settlements are distributed in the central-eastern and southern parts,with desert areas concentrated in the mid-west.Ecological quality and function,characterized by NPP and NDVI,show a gradient of low in the northwest and high in the northeast,with an overall improving trend.However,a cycle of"water limitation,low function,and aggravated degradation"persists in the mid-west,and farmland expansion in the east leads to ecological fragmentation,with the core issue being an imbalance in the water cycle.Regarding driving mechanisms,precipitation is the dominant natural factor,showing a significantly higher correlation with ecological function than temperature.Human activities exhibit a dual effect:Ecological engineering promotes an increase in ecological land,while unsustainable development and water resource utilization exacerbate local degradation.Hydraulic engineering and water resource management influence pattern dynamics through both positive and negative coupling effects on the water cycle.Consequently,a multi-level"point,corridor,and network"optimization system is constructed,identifying 31 core ecological sources and 22 ecological corridors and delineating four types of zones.Differentiated strategies are proposed,including natural restoration for the northeast and enhanced artificial intervention with water infrastructure support for the west.Furthermore,promoting water-saving irrigation and ecological water supplementation and establishing an integrated"sky,space,and ground"monitoring network are recommended.This research provides a scientific basis for strengthening the northern ecological security barrier and coordinating ecological protection with economic development.