基于土地利用变化的西宁市景观生态风险识别及优化策略

Landscape ecological risk identification and optimization strategy in Xining City based on land use change

景观生态风险评价作为国土资源空间优化配置与生态资源管理决策设计的综合手段,为区域生态安全定量化评估提供了新思路。本研究分析了1980—2020年西宁市土地利用时空演变特征以及景观生态风险时空分异特征。结果表明:(1)草地占西宁市总面积的51%以上,以中/低覆盖度草地为主,1980—2020年耕地面积减少97.42 km^(2),建设用地增加103.89 km^(2)。(2)2000年以前土地利用结构相对稳定,2000年以来土地利用变化程度活跃。40年间耕地转出面积最大,为109.69 km^(2),建设用地转入面积最大,为104.44 km^(2)。(3)5个时期西宁市景观生态风险指数均在0.288左右,景观生态安全状况总体稳定,景观生态风险等级以低生态风险等级和较低生态风险等级为主,占西宁市面积的70%以上。(4)5个时期西宁市景观生态风险全局Moran’s I值分别是0.712、0.720、0.724、0.741、0.764,呈现以低-低聚集和高-高聚集为主的空间分布格局,空间自相关程度逐渐增加,空间趋同趋势不断增强。土地资源优化配置路径包括:科学估算土地利用结构中生产、生活、生态用地的规模阈值,避免生产、生活用地过度开发利用挤占生态空间,修复和改善草地、耕地资源质量,强化和提升林地资源生态功能和价值溢出效益,合理规划建设用地开发规模和强度,培育水域、建设用地景观生态廊道,适度增加建城区生态用地规模,可以保障西宁市生态安全格局健康稳定。

Landscape ecological risk assessment is a comprehensive means for the spatial optimization allocation of land resources and the decision-making design of ecological resources management,which can provide a new idea for quantitative assessment of regional ecological security.We analyzed the characteristics of the temporal and spatial variations of land use in Xining City from 1980 to 2020,and explored the characteristics of the temporal and spatial variations of landscape ecological risks.The results showed that:(1)Grassland accounted for more than 51%of the total area of Xining City,mainly with medium/low coverage grassland.From 1980 to 2020,the area of cultivated land decreased by 97.42 km^(2),while the construction land increased by 103.89 km^(2).(2)The land use structure was relatively stable before 2000,and the degree of land use change was active after 2000.During the four decades,the area of transferred from cultivated land was the largest at 109.69 km^(2),while the area transferred into construction land was the largest at 104.44 km^(2).(3)The landscape ecological risk index of Xining City was 0.288,and the landscape ecological security status was generally stable.The ecological risk levels were mainly at low and the relatively low ecological risks,accounting for more than 70%of Xining's area.(4)The global Moran's I values of Xining's landscape ecological risk in the five periods were 0.712,0.720,0.724,0.741,0.764 respectively,with a spatial distribution pattern being dominated by low-low and high-high clusters.The degree of spatial autocorrelation increased gradually,and the trend of spatial convergence strengthened continuously.The paths of optimal allocation of land resources include:scientifically estimating the scale threshold of production,living,and ecological lands in the land use structure,avoiding excessive development and utilization of production and living land and occupying ecological space,improving the quality of grassland and arable land resources,and strengthening the overflow benefits of ecological functions and values of woodland resources,rational planning of the scale and intensity of construction land development,cultivating landscape ecological corridors of waters and construction land,and moderately increasing the area of ecological land in the urban area.Such suggestions may ensure the continued improvement of ecological security pattern in Xining City.