北京明长城沿线景观生态风险评价
Assessment of ecological risks of landscape along the Ming Great Wall in Beijing
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摘要: 为了解北京明长城沿线周边地区的生态风险状况,以北京市长城普查数据和近期森林资源调查数据为数据源,通过构建景观生态风险指数,以2km×2km的网格进行系统采样,借助空间自相关和半方差分析方法,探讨北京明长城两侧3km范围内的景观生态风险状况。结果表明:各景观类型中,灌木林地所占面积比例最高,达26.58%,但其生态风险程度也最高,无立木林地破碎度和分离度最高,所受干扰程度和自然损失度也最大,农地斑块形状最复杂。研究区生态风险分布存在明显的尺度效应,存在一定数量的高风险和低风险聚集区,聚集现象显著,具有较高的空间相关性,其中高风险区域主要位于八达岭、黄花城、慕田峪、金山岭以及司马台等著名长城段;同时,生态风险在空间上表现出以怀柔东南部与密云接壤处为中心,向研究区东西两侧风险逐渐递减的圈层结构特征。研究区整体风险以中等偏下等级为主,但较高和最高等级风险所占的面积比重达到21.09%,不容忽视。本文较为详细地分析和介绍了北京明长城周边地区的生态风险状况,为日后生态环境的保护和规划建设提供参考。Abstract: In this study we evaluated the ecological risks of the landscapes along the Beijing Ming Great Wall, 3 km within each side of it. Firstly we built landscape ecological risk indices by using the data from Beijing Great Wall census and recent forest resource survey, then systematically sampled in each 2km×2km grid, and analyzed the data by spatial autocorrelation and analysis of semi-variance. Among the landscapes studied, shrub land had the highest coverage (26.58%) and also the highest ecological risk; Non-stumpage land had the highest degree of fragmentation and isolation and therefore suffered the highest disturbance and natural loss; agricultural land had the most complex shape. The spatial autocorrelation based on global Moran's I was 0.2725 and the nugget coefficient was 49.7%, suggesting that the ecological risk indices were spatially auto-correlated and scale-dependent; spatial autocorrelation generally decreased with the increase of research scale. Therefore, ecological risk was aggregated, with apparent high and low risk zones. The areas with high eco-risk were mainly in the more developed and well-known sections of the Great Wall including Badaling, Huanghuacheng, Mutianyu, Jinshanling, and Simatai. The ecological risk peaked at the border between southeast Huairou and Miyun and decreased gradually to the east and the west. The most of the study area was in medium to low ecological risks; however the percentage of area with high risk reached 21.09%, high enough for further attention. Our results would provide reference for environmental protection, policy development and conservation planning in the future.