徐州城区道路绿地物种丰富度的空间分布特征

Analysis of Spatial Distribution Characteristics of Species Richness of Urban Road Green Space in Xuzhou City

为了弄清城市绿地物种丰富度的空间分布特征,以徐州市区绕城公路内的道路绿地为研究对象,沿东西和南北两条主干道设置调查样地,进行了植物群落学调查,在此基础上统计各样地植物群落的物种丰富度,并运用空间自相关分析和半变异函数,分析了城区道路绿地物种丰富度的空间自相关程度及空间分布规律。结果表明:徐州城区道路绿地的物种丰富度不高,平均每块样地约出现25个物种,其中人工栽植物种超过1/3,非人工栽植的野生物种主要出现在草本层。城区道路绿地的物种丰富度沿市中心向郊区方向呈逐渐增加的趋势;道路绿地物种丰富度的空间分布存在聚集区,物种丰富度较高的绿地明显聚集在城市东部区域,城市中心区域的物种丰富度普遍较低。在群落、草本层和野生草本层(由野生物种构成的草本层)三个水平上,导致物种丰富度空间分布差异的因素不同,在群落和草本层水平上受结构性因素和随机因素的共同影响,在野生草本层水平上主要受结构性因素的影响。城区道路绿地的物种丰富度具有各向异性,但在距离2000m左右的范围内,物种丰富度的半变异函数变化幅度较小,各方向物种丰富度的空间关联性较为一致;在2000m之后随着距离增加,各向异性逐渐明显。物种丰富度的空间变化特征与绿地周边的景观格局、物种的扩散途径等密切相关。

In order to clarify the spatial distribution characteristics of species richness of urban road green space,the urban road green space in Xuzhou city was taken as the research object,survey samples were set up along main roads running east to west and south to north,and the sample communities were investigated based on plant community method. Then,the species richness of the communities were statistics,and their spatial autocorrelation and spatial distribution regular were explored using spatial autocorrelation analysis and semivariograms analysis. The results showed that the species richness of urban road green space is not high,and there are about 25 species in each sample. Among them,more than 1/3 of plants are planted species,and non-planted wild species mainly appear in the herb layer. The species richness of urban road green space increased gradually from urban center to suburbs. The spatial distribution of species richness in urban road green spaces has a gathering area,i.e. the road green spaces who have higher species richness usually gather on the eastern region,but those of the lower species richness were more frequently occur in the center. In the three levels of community,herb layer and wild herb layers (herb layer composed of only wild species),the factors which lead to the spatial distribution difference of species richness in urban road green spaces are different. The spatial distribution difference of species richness between communities and herb layers is caused by both structural factors and random factors,but that of between wild herb layers mainly affected by structural factors. The species richness of urban road green space is anisotropic,but within the range of about 2000m,all the semivariograms of species richness in each direction are less variable,and the spatial correlation of species richness in all directions tend to consistent;after 2000 m,the anisotropy gradually became apparent as the distance increased. The spatial variation characteristics of species richness in urban road green space are closely related to the landscape pattern around the green space and the diffusion ways of the species.