城市基质对城市遗存自然山体植物群落物种多样性的影响——以贵阳市为例

Exploring the relationship between the plant diversity of the urban remnant mountains and its surrounding urban matrix characteristics:A case study of Guiyang City

多山地区城市扩展过程中,建成区内遗存有大量自然山体,形成城市人工基质“海”中的遗存山体“岛屿生境”,这些城市遗存山体长期受到来自城市人工环境的各种间接或直接的干扰。为探索城市基质与城市遗存自然山体植物群落多样性之间的关系,以黔中地区典型的喀斯特多山城市——贵阳为研究区域,按不同规模选择15座城市遗存山体,每座样山按坡向+坡位组合方式设置群落调查样地,共设置143个样地;以样山边界为基准,100 m为步长向外设置20个缓冲区,总宽度为2000 m,计算缓冲区总不透水表面积(PTIA)、植被覆盖度(VC)、破碎化指数(FI)、土地利用(LU)4个城市基质特征指标。运用Pearson相关分析和线性回归模型分析了城市基质特征指标与城市遗存山体植物群落物种多样性之间的相关关系。结果表明:(1)PTIA对不同规模城市遗存山体整体植物多样性的影响都存在明显空间尺度效应,在2000 m时相关性最高,呈显著正相关;不同规模城市遗存山体整体植物多样性与单个或多个LU类型存在显著相关性,但影响效应存在显著差异;VC、FI与城市遗存山体整体植物多样性无显著相关关系;(2)不同规模城市遗存山体各层次植物多样性与城市基质特征4个指标在不同的空间尺度上均存在显著相关性;(3)城市遗存山体植物多样性Shannon-Wiener指数(H′)与每个城市基质特征指标一元线性回归拟合度高,而多元回归R^(2)为0。探明城市基质特征对城市遗存山体植物多样性具有一定的影响,但影响规律不一致且存在空间尺度差异,说明城市人工环境对城市遗存山体植物多样性维持的影响非常复杂,需要从不同的角度开展深入的研究,才有可能揭示城市遗存山体植物多样性的城市化响应机制,进而指导城市遗存山体保护规划与管理。

In the process of urban expansion in mountainous areas,there are a large number of natural mountains remained in the urban built-up area,forming the urban remnant mountain“island habitat”in the urban artificial matrix“sea”.These urban remnant mountains(URMs)have long been affected by a variety of indirect or direct interference from the urban artificial environment.To explore the relationship between the plant diversity of the URMs and its surrounding urban matrix characteristics,taking the urban built-up area of Guiyang,a typical karst mountainous city in central Guizhou,as the research area,fifteen URMs were selected according to different sizes as research objects in this study.The sample spots of each URM were set by the combination way of slope direction and slope position.A total of 143 plant diversity survey plots were set up on the fifteen URMs.Taking the edge line of sample URMs as datum,buffer zones were set successively outward at step lengths of 100 m and 20 buffer zones were set with a total width of 2000 m.The proportion of total impervious surface area(PTIA),vegetation coverage(VC),fragmentation index(FI)and land use(LU)of each zone were calculated.The correlation between the urban matrix characteristic indices and the species diversity indices of the URMs plant communities was analyzed using the Pearson correlation analysis and the linear regression model.The results showed that:(i)the influence of PTIA on the overall plant diversity of different size URMs had obviously spatial scale effects,with the highest correlation and significantly positive correlation at 2000 m;The overall plant diversity of different size URMs were significantly associated with a single or multiple LU types,but the impact effects were significantly different;There was no significant relationship between VC and FI and the overall plant diversity of URMs.(ii)The plant diversity indices of all plant levels of different size URMS were correlated with the four indices of urban matrix characteristics at different spatial scales.(iii)The Shannon-Wiener index(H′)had a high linear regression fit to each urban matrix index,however the multiple regression R^(2) was 0.In this study,it was explored that the urban matrix characteristics had some influence on the plant diversity of URMs in different scales,but the influence laws were inconsistent.It shows that the impact of urban artificial environment on the maintenance of plant diversity of URMs is very complex.It is very necessary to conduct in-depth research from different perspectives to reveal the urbanization response mechanism of plant diversity of URMs,and then guide the protection planning and management of URMs.