Studies On Impacts Of Green Space In Wuhan On Heat Island Effect-Based On Living Vegetation

As China’s increasing levels of urbanization, urban environment problems have become increasingly prominent, urban heat island effect grows sequentially, the ecology benefit of urban green space draws more and more attention. This paper taking living vegetation volume of green space as the entry point, makes research on the mitigation of urban heat island effect by green space and its pattern, from two different levels, patch and community of urban green space, to guide the planning and construction of urban green space in the future.Taking LVV of green spaces as the entry point, this paper investigates and calculates the LAI of the different plant communities within the third ring of roads in the central city of Wuhan; and sets up a linear relative equation which indicates the relationship between the LAI of the experimental plots and the VI extracted from the remote sensing image, to make a regression to get the overall LAI distribution of the central city in Wuhan. Based on the actual measurement data, this paper makes quantitative analysis of the plant communities’ structures, and compares the extinction ratios of solar radiation of vegetation with different structures; on the basis of the LVV overall distribution of the central city in Wuhan and the land surface temperature in Wuhan which generated earlier, makes quantitative analysis of the temperature-lowering pattern within the vegetation patches and vegetation patches’ effect distance to surrounding environment, to get the urban vegetation’s mitigation pattern of urban heat island. The main results are as follows: (1) Use index models to make regression and fit of communities’measured LAI and NDVI, the regression equation is:y=1.333* exp(2.975x); (2) The structure-differential communities’ extinction ratios of solar radiation mainly depend on the canopy cover degrees, and the ratios of highly closured communities are significantly higher than the sparse communities, highly closured and multi-storied mixed communities stratified absorbance maximum; (3)The drop range in temperature within the urban vegetation patches is mainly effected by the patches’ area and LAI, and the LVV amount of urban vegetation patches integrated reflect the affection; (4) The amount living vegetation volume of urban vegetation patches and its effect distance of surrounding environment temperature are closely related. However, as the environment changes, its effect distances are different.