城市绿地空间格局及其环境效应——以宜昌市中心城区为例

The different urban green-land spatial patterns and their environmental effects:A case of the central district of Yichang city,Hubei Province

城市绿地在改善城市环境及维护城市生态系统平衡中起着极为重要的作用 ,而当绿地覆盖率小于 4 0 %时 ,绿地整体生态效益的发挥主要取决于绿地的内部结构和空间布局 ,但迄今为止缺乏绿地景观分布格局与环境效应关系的研究报道。本研究应用景观生态学原理 ,分析了湖北省宜昌市中心城区斑优格局、斑匀格局、廊道格局和对照格局等四种景观结构及其绿地分布格局 ,选取了气温、相对湿度、环境噪声和大气 SO2 、NOx、TSP含量等环境监测指标 ,观测了不同绿地景观格局下的环境效应 ,并对比分析了绿地分布格局指标与综合环境效应间的关系 ,以便提出城市绿地系统布局合理性指标 ,为城市绿地系统的景观结构优化提供依据。研究结果表明 ,斑优格局、斑匀格局、廊道格局和对照格局等四种不同景观在斑块总面积、建筑斑块面积和无绿化道路面积等景观总体格局上较均衡 ,但由于其绿化覆盖率及绿地景观分布格局差异较大 ,致使其环境效益也表现出明显的差异。其中 ,对照格局景观的绿地斑块总面积最小 ,绿地破碎化指数最高 ,绿化覆盖率仅为 1.0 0 % ,以建筑铺装斑块和无绿化道路廊道为主要景观构成。因此 ,对照格局景观的环境气温较高、空气相对湿度低、环境噪声较大、大气 TSP含量高 ,景观环境恶劣。

The urban green-land system plays an important role in improving the quality of urban environment and maintaining the balance of urban ecological system. However, the whole ecological benefit of green-land system is mainly determined by green-lands' internal structures and spatial patterns when the percentage of green-land coverage is less than 40%. So far there hasn't been any research on the relationship of urban green-land spatial pattern and its environmental effect. In this paper, the four types of landscape structures and their green-land landscape patterns, including the landscapes of dominant green-land patch pattern, even green-land patch pattern, dominant wooded corridor pattern and building or concrete covering pattern (control) on the central district of Yichang city in Hubei province, were analyzed on the basis of landscape ecological principle. The environmental effects of all landscapes were monitored at the same time, by means of the selected environmental parameters of air temperature, relative air humidity, atmospheric noise and the content of SO_2, NO_x and total suspension particle (TSP) respectively. The relationship of the green-land landscape patterns and their environmental effects were analyzed by comparative method, in order to put forward the rationalization parameters for optimizing the landscape structure of urban green-land system.The results showed that, though there was an unanimous general structure, such as roughly the same of total patch area, building or concrete covering patch area and woodless corridor area between the four landscapes, the environmental benefits were significantly different due to the unequal green-land coverage and the varied green-land landscape patterns. In which, the landscape of building or concrete covering pattern (control) was mostly composed of woodless corridors and building or concrete covering patches, which the green-land had the least total patch area and the tiptop fragmentation index, while the percentage of green-land coverage is only 1.00%. Therefore, there were adverse circumstances with the relatively higher air temperature, atmospheric noise, TSP content and the lower relative air humidity in the landscape. The landscape of dominant green-land patch pattern had the highest green-land coverage (up to 43.59%) and average patch area of green-land (29118m^2) dominated by great green-land patches. In which, the green-land patches having the highest dominance and the least fragmentation index, coexisted with wooded corridors in possession of the relatively higher total area and average area. The environmental effects of the landscape of dominant green-land patch pattern expressed mainly in air temperature decreasing, relative air humidity raising, atmospheric noise reduction and dust retention, in which the average relative air humidity increased by 5.93%, the average atmospheric noise weakened by 28.12% and the TSP content reduced significantly by 86.42% while the contents of SO_2 and NO_x had no significantly difference comparing to the control. The landscape of even green-land patch pattern had the relatively lower green-land coverage (11.34%), dominance and fragmentation index of green-land patch, while the total area and average area of wooded corridor were bigger than that of green-land patches. The green-land landscape with a regular distribution in the landscape was mainly composed of the middle or small green-land patches coexisting with wooded corridors. Comparing to the control, the average relative air humidity increased distinctly by 4.64%, the TSP content reduced obviously by 46.62%, the air temperature and atmospheric noise also had an obviously decreasing in the landscape, which revealed the same effects as the landscape of dominant green-land patch pattern. But the effects of dust retention and atmospheric noise reduction were only 53.95% and 12.45% of that in the landscape of dominant green-land patch pattern, respectively. There were only 6.13% green-land coverage and the smaller total and average area of green-land patch in the land