| Urban green space,as an important part of urban ecological system,plays an irreplaceable role in balancing urban ecology,improving environmental quality,mitigating heat island effect and beautifying urban image.In recent years,with the continuous rapid evolution of urbanization in Hefei,a series of eco-environmental problems have arisen,and the spatial structure and landscape pattern of urban green space have changed greatly.Therefore,it is of great significance and reference value for improving urban ecological environment,planning urban space rationally and optimizing the allocation of public resources to analyze the temporal and spatial evolution of green landscape pattern.Based on the theories and methods of landscape ecology,“3S” technology and spatial analysis technology,this paper takes Hefei green space as an example to analyze the characteristics and laws of green space evolution from many aspects and scales,and discusses the driving factors behind the evolution of green space pattern.The specific research results are as follows:(1)Firstly,the land cover types of Hefei City are divided into two categories: green space(green land,water body,farmland)and non-green space(construction land,bare land).The results show that the area of green space decreased by 72268.38 hm~2 during1995～2017,accounting for 6.32% of the total land area.Among them,farmland patches changed the most,the proportion decreased by 11.26%,the proportion of green land increased by 4.19%,and the water body increased slightly.Based on Fragstats3.3,the green space pattern index was calculated and analyzed.The patch heterogeneity was enhanced,the patch shape became complex and irregular,the patch connectivity and cohesion became poor,and the landscape was fragmented.(2)Secondly,from the perspective of different regional scales,(1)The overall dominance and fragmentation degree of green space in the central urban area have increased significantly,and showed the characteristics of gradient change along the circle layer,while the dominance and connectivity of circle layer patches far from the central urban area are higher,the shape is more complicated and the fragmentation degree is higher.(2)The green space area of each suburban county showed a downward trend,the patch became more fragmented and complicated,and increased along the gradient of the circle layer.(3)The green spatial dominance of 12 axial districts decreased significantly,and the patches tended to be scattered,complicated and fragmented.However,with the construction of ecological patches and road corridors,the overall connectivity and diversity increased.(3)Furthermore,the green space area of the old urban district in the second ring road and the Binhu new district of Hefei decreased by 23.22% and 26.86% respectively,both of which were significant reductions of farmland,with the proportion reduced by 23.59%and 42.1% respectively,but the proportion of green space in the new district increased by 15.12%,largely making up for the loss of green space.Based on the calculation of landscape pattern index,it is found that the shape of green space patches tends to be regular,the dominance and connectivity increase by 2.58 and 4.29 respectively,and the degree of fragmentation decreases by 57.38,the shape tends to be complex and fragmentation deepens further,and the landscape structure is unstable.(4)Finally,according to the trend of landscape pattern evolution and the analysis of relevant statistical data,population factors,social economy,policy factors and traffic factors are the main drivers of green space evolution in Hefei. |
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