Assessment of ecological integrity and analysis of its influencing factors in Zhangjiakou City

Anthropogenic disturbances, such as urbanization and agricultural production, significantly contribute to the degradation of regional ecosystems. While the concept of human-integrated impact assessments is widely recognized, regional assessment methods based on ecological integrity are less present in China. This study addresses this gap by examining Zhangjiakou City, a critical area for water source conservation and ecological support for Beijing. We employed a landscape condition model to evaluate six anthropogenic disturbance indicators: slope gradient of cropland, distance from grassland to the nearest settlement, distance from surface water to the nearest settlement, urban area size, road grade, and railway grade. These indicators encompass four domains: agriculture and pastoral production, surface water utilization, urbanization, and transportation infrastructure. To quantify the impact scores and maximum impact radius for each indicator, we used a participatory method. This approach led to the creation of separate data layers, each numerically valued from 0 to 1, for each disturbance indicator. These layers were then synthesized into a continuous ecological integrity index using the product method. We conducted spatial autocorrelation, hotspot, sensitivity, and commonality analyses to explore the spatial distribution, clustering characteristics, and primary influencing factors of ecological integrity in 2000 and 2022. Our findings revealed a distinct spatial distribution pattern in Zhangjiakou City: high ecological integrity was observed in the eastern regions, whereas lower integrity characterized the central and western areas. This pattern was influenced by regional resources, transportation, and development orientation. Between 2000 and 2022, a polarization phenomenon in the human impact on ecological integrity was observed. Specifically, human disturbance decreased in areas with high ecological integrity but increased in areas with lower integrity, indicating diverse levels of anthropogenic influence across different regions. In the eastern part of Zhangjiakou City, the high ecological integrity areas are distributed in blocks along with the forest land due to the implementation of ecological restoration projects. Conversely, road construction has created a low-integrity spatial distribution pattern in the central regions, emanating from urban centers and radiating along major roads. The western region, impacted by agricultural and pastoral activities, did not exhibit clear clustering characteristics of ecological integrity. Our study identified cropland, roads, and grassland as the primary factors influencing the ecological integrity of Zhangjiakou City. To mitigate these impacts, we recommend enhancing forest landscape restoration in the eastern region. For the central region, clear boundaries for highway development should be delineated in accordance with the ecological protection guidelines. Additionally, efforts to convert farmland to grassland in the western region should be intensified to improve water supply and enhance the ecological carrying capacity. These initiatives aim to establish an ecological security barrier in the northwest of Beijing and improve the resilience of the region to anthropogenic pressures. This study provides an effective scientific methodology and a technical reference for human-integrated impact assessments of regional ecosystems. This underscores the importance of tailored management interventions based on the spatial aggregation of ecological integrity to address specific challenges posed by anthropogenic disturbances. Such targeted interventions are crucial for promoting sustainable development and enhancing ecological resilience in regions under significant human pressure.