| Urban green space is an important part of urban ecosystem,its development is effected by multiple factors of the human and the natural environment,urban forest is an important regulator of ecological function in urban life.Both have a positive effect on maintaining the stability of urban ecosystems and satisfying urban ecological service functions,and they can alleviate a series of problems caused by rapid urbanization to a certain extent.At present,the research on the landscape pattern of urban green space and the ecological service function of urban forest are gradually increasing,but these studies are basically qualitative research,and the quantitative analysis is less.Based on the landsat satellite image data,this paper analyzes quantitatively the evolution law of urban green space and the change of gradient,and explores the distribution of urban forest patches,service effect and rational layout in certain service distance of Anning District in Lanzhou City.The results showed:(1)In recent years,the number and area of green patches have increased to a certain extent in built up area district of Anning,but the distribution is uneven and the degree of fragmentation is high,and the degree of fragmentation is the largest in the center of district,its show that landscape pattern affected by the development of urbanization.(2)Analysis on the shape index and the degree of polymerization of the landscape components,the shape index is larger and the polymerization index is lower in the radiation area of the central location,indicating that the discreteness is higher and the degree of fragmentation is also larger in the center range,the degree of polymerization is only higher in the suburbs,green patches to a small number of large patches connected highly in the landscape.(3)The total number of urban forest patches were 17 in Anning area,the patchdensity was 14.16,the spatial distribution of urban forest was uneven,and the urban forest patches were mainly distributed in the middle and east of the study area.The whole of service effect function was not balanced.(4)At the distance of 500 m,1000m and 2000 m,the number of patches and areas of urban forest service were 49,31.92%,113,60.97%,155 and 78.92% respectively.From the overlapping area of different service conditions,the maximum overlap ratio is 71.82%,indicating that the residents of this area have greater selectivity.After the construction of potential patches,the service effect of urban forest patches was significantly improved,and the number of patches and area of residential area were 63,38.02%,139,75.39%,183,96.18%.(5)The gap between the eastern and western ecological construction in the eastern part of the study area is large,and there are still some available agricultural land and unused land in the western region,the distribution of the settlements in the western suburbs is more fragmented,so the development space of the urban forest is larger,it can be used as a breakthrough in construction of the forest city in the future.Key words: urban green space;Landscape pattern;Urban forest;service effect. |
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