“城-郊”居住区植被格局和植物多样性变异及其驱动因子研究

In China, almost 75% of people living in developed regions specifically reside in urbanized areas, and 41% of urban land area is used for homes and their surroundings (i.e., residential places). Urbanization is an inevitable trend in China's future development, a process that will result in dramatic land-use changes and create serious eco-environmental problems. Therefore, finding ways to mitigate the effects of urbanization is critical. In residential areas, the eco-environmental impact of urbanization can be better understood through a comprehensive study of vegetation spatial patterns and plant diversity variation. By revealing these patterns, targeted measures for improving the environmental quality for both wildlife species and humans can be devised..In our study, we will use a stratified design (sampling density urbanized: sub-urbanized areas of 3:1) along a gradient of urbanization intensity in Beijing. Through multivariate analyses (canonical correlation analysis, multiple regression, tree regression), we will assess land use traits (such as the proportion of green space in residential areas, degree of fragmentation, distance from the urban center), and vegetation characteristics (such as plant community similarity, plant abundance, richness and evenness, and the proportion of alien plant species). We will also consider: (1) socio-economic variables, such as average level of education, average household income, average house age, average house price, and average number of family members, (2) residential greening and management variables such as monthly greening fee, frequency of shearing and mowing, and (3) environmental factors such as temperature, humidity, soil temperature, hardness, compaction, etc. Much of this information will be retrieved from bibliographical sources as well as by personal and telephonic interviews (at least 20 households in each residential area)..In general, the main aims of the proposal are to: (1) assess how the spatial structure of socio-economic, ecological, and physical features in residential green space relate to each other in a highly complex urban system, (2) explore the evolutionary mechanisms between urban system structure and ecological process; (3) provide scientific information to the Beijing Municipal Bureau of Landscape and Forestry through reports and manuals for the planning, design and management of residential green space.

城市化是我国未来社会发展的必然趋势，由此带来的土地利用变化和生态环境问题是生态学研究的热点问题之一。我国发达地区75%的人口生活在城市里，而城市里41%的土地用于居住区及其周围的环境。作为城市和郊区的基本组成单元，研究城郊居住区土地覆盖格局和植物多样性变异是理解城市化对生态环境影响的模式之一。本研究拟以北京市城郊梯度下的居住区绿地为研究对象，通过遥感解译和野外调查获取居住区的土地覆盖格局和植被特征的空间变异，定量分析其与市中心距离及人口密度等变量之间的相关性，揭示城市化对居住区植被格局和植物多样性的影响；通过问卷调查和定位实验观测获取驱动居住区植被特征变异的社会经济、自然环境和养护管理因子，分析驱动因子与居住区植被特征变异的耦合关联，揭示城郊居住区各组分之间的相互作用机理，探索城市生态系统中格局和过程之间的演变机制，为城市的绿化管理提供科学依据。

作为城市生态系统的重要组成部分，城市植被在城市环境、社会功能和经济效益等方面中发挥着不可替代的作用。居住区是城市生态生态系统的“拟南芥”，它为探索高度异质性城市生态系统中各组分之间的相互作用关系提供了模式。本研究运用遥感、固定样地、社会经济问卷和统计年鉴查询等方法系统性地调查了北京市五环内453个城市结构单元的土地覆盖状况、物种多样性和社会经济状况（建成期，房价等）。对83个居住区的植物多样性与多度、社会经济因子和空间因子等进行了主成分分析、非线性模型和一般线性模型等分析。453个城市结构单元属12个不同的一级城市功能单位和38个不同的二级城市功能单位。在一级功能单位，不透水地表的占地百分率在公共服务区达最高（75.64% ± 4.86 %, n = 23）。在二级功能单位，不透水地表的占地百分率在宾馆区达到最高（87.29 % ± 9.86 %, n =3）。高等学校、公园和高密度住宅区的绿化率与各自的建成期之间无显著性相关关系，而住宅区的绿化率与房价呈倒“U”型显著相关，具体方程式为：f = 17736.45 + 348.21 x – 4.15 x2，p = 0.0022 < 0.05。高密度城市化区的面积百分率，低密度城市化区的面积百分率和森林面积比例呈中度（或弱）负相关。土地覆盖类型因子之间，只有高密度城区和与市中心距离（r = -0.433, p < 0.05）和人口密度 （r = 0.315, p < 0.05）显著相关；到市中心距离与人口密度显著相关（r = -0.613, p < 0.05）；草本植物的物种丰富度与乔灌植物的密度（非丰富度）更相关（r = - 0.472, p < 0.05）。 83个居住区共发现369 种植物隶属99科150属，一年生、外来植物、花粉致敏植物和可食用或药用植物种数分别为90、174、169和133。多年生植物，外来植物和可观赏或可食用植物种数在1990s的居住区最高。乔灌木的Simpson, Shannon和Pielou指数在1990s的居住区最高，草本的Simpson, Shannon和Pielou指数在1980s之前的居住区最高。一般线性模型显示各类多样性和房价显著相关，主成分分析显示房价和容积率是影响各类多样性的主要因子，建议形成外来和花粉致敏植物名录以有效减少城市植物非生态系统服务功能。