基于加权核密度的高原高海拔地区路网格局与景观生态风险时空变化

Temporal and spatial changes of road grid and landscape ecological risks in high altitude plateaus based on weighted kernel density

针对景观生态风险的研究多着眼于城市或河流流域,而高原高海拔地区景观生态较为脆弱,道路网络的发展容易导致区域景观破碎化和景观生态格局变化,从而影响区域内生态环境质量的问题,以拉萨市为例,在地理信息系统的支持下,采用加权核密度估算(WKDE)、生态足迹模型、景观指数分析法、空间分析方法研究路网扩张对沿线景观格局的影响及其生态风险变化。基于景观格局构建拉萨市景观生态风险模型,对该地区2012年和2020年路网格局和景观生态风险的时空变化进行研究。研究结果表明:加权核密度分析可以更加真实地反映高原高海拔地区道路网络实际状况及其生态影响,路网扩张导致建设用地面积快速增加以及耕地面积减少,对其他景观类型的影响很小;拉萨市路网扩张对生态环境压力起促进作用,且引起的景观生态风险变化的差异与地形密切相关,主要表现为低海拔的城市中心风险等级下降;随着生态风险等级的升高,研究区域内各等级道路的长度占比表现出先上升后下降趋势,这说明景观生态风险和道路等级之间具有一定的相关性。研究成果对高原高海拔地区的路网规划和生态管理具有一定的参考价值,可为相关地区道路沿线生态修复工作提供理论与技术支撑,也为未来在高原高海拔环境工程实证研究提供参考。

Aimed at the problem that current research on landscape ecological risk mostly focuses on cities or river basins,while the landscape ecology in high altitude areas of the plateau was more fragile,and the development of road networks was likely to lead to the problems of regional landscape fragmentation and changes in landscape ecological patterns,thus affecting the quality of the ecological environment in the region.The impact of road network expansion on landscape pattern along the route and the change of its ecological risk were studied in Lhasa City,Tibet Region,with the support of geographic information system(GIS),and weighted kernel density estimation(WKDE),ecological footprint modeling,landscape index analysis method,and spatial analysis method were used.A landscape ecological risk model of Lhasa City was constructed based on the landscape pattern,and the spatial and temporal changes of the road network pattern and landscape ecological risk in the region were studied for two periods,2012 and 2020.The results show that the weighted kernel density analysis can more realistically reflect the actual condition of the road network and its ecological impacts in the high plateau and high altitude areas.The road network expansion led to a rapid increase in the area of construction land as well as a decrease in the area of cultivated land,with little impact on other landscape types.The road network expansion in Lhasa City contributes to the ecological pressure,and the differences in the landscape ecological risk changes caused are closely related to the topography,which is mainly manifested in the decrease of the risk level of the urban centers at low altitude.As the ecological risk level rises,the length percentage of roads of each level in the study area shows a tendency of increasing and then decreasing,which indicates that there is a certain correlation between landscape ecological risk and road level.The research results have certain reference value for road network planning and ecological management in high plateau and high altitude areas,can provide theoretical and technical support for ecological restoration work along roads in related areas,and will also provide reference for future empirical research in the important field of high plateau and high altitude environmental engineering.4 tabs,9 figs,41 refs.