北京明长城两侧森林景观异质性和复杂性变化

为了分析北京明长城森林景观结构的空间异质性和斑块形状复杂性,以北京明长城两侧3 000 m范围为研究区域,在选取各类最常用指数的基础上,结合分形理论构建了复杂性评价指标,运用缓冲区分析方法对研究区不同缓冲幅度下的景观异质性与斑块形状复杂性状况进行了分析。结果表明:1)有林地和灌木林地分布面积较广,占总面积的83%左右,为研究区的优势景观。其中,有林地为景观基质,聚合性最强,连接性最好,破碎化程度最低;而疏林地和无立木林地斑块间离散程度高,景观连接性差,破碎化程度高。2)随着缓冲距离的扩大,同类型景观斑块邻近度增高,离散程度降低,景观连接性增强,平均斑块面积变大,破碎化程度在降低,景观异质性有所增强,斑块类型趋向于均匀分布。3)随着缓冲距离的扩大,景观斑块形状复杂程度逐渐增加,边缘效应影响也随之增强,景观结构稳定性则逐渐递减。 

Spatial heterogeneity and complexity of forest landscape along the Ming Great Wall in Beijing

We analyzed the spatial heterogeneity and patch shape complexity of a forest landscape within 3000 m on both sides of the Ming Great Wall in Beijing. A complexity evaluation index was developed based on the most commonly used landscape indexes, along with the use of fractal theory. The buffer analysis method was used to examine the landscape heterogeneity and patch complexity under different buffer amplitudes. The results showed that:1) Forest land and shrub land were the most widely distributed and dominant landscape types, accounting for about 83% of the total study area. Forest land represented the landscape matrix with the strongest aggregation, best connectivity and lowest degree of fragmentation;open forest and non-stumpage forest land had a high degree of discrete patches, poor landscape connectivity and high fragmentation. 2) With the increase of buffer distance, the proximity of the same kind of landscape patches, landscape connectivity, average patch size and landscape heterogeneity increased. The amount of discrete patches and fragmentation decreased, and patch types approached a uniform distribution. 3) The expansion of buffer distance also gradually increased patch shape complexity and the influence of edge effects, but diminished landscape structure stability. These results show that a historical monument, like the Ming Great Wall of China, may have a significant effect on the surrounding landscape.