Research On The Dynamic Change And Driving Mechanism Of Green Space Landscape Pattern In Yan’an City

Yan’an City is located in the Loess Plateau.The surface ravines are vertical and horizontal,the soil is soft,the soil erosion is serious,and the ecological environment is relatively fragile.Yan’an urban area is a densely populated and economically active area in Yan’an.With the acceleration of urbanization,the contradiction between urbanization and the carrying capacity of resources and environment has become increasingly prominent,and the ecological space land has been continuously eroded,which further affects the ecological security of the urban area.The ecological functions of urban green space,such as maintaining water and soil,purifying air,and conserving water sources,can effectively alleviate urban ecological problems and are the main regulators of the urban environment.This paper takes the fragile Yan’an urban area as the research area,takes landscape ecology as the theoretical basis,uses RS,GIS and ENVI as the correlation analysis technology,uses Landsat and DEM images as the main data sources,and mainly uses quantitative methods to describe the Yan’an urban area.Green space landscape pattern changes,and further analysis of the main reasons for the changes,mainly get the following five conclusions:(1)The green space landscape pattern of Yan’an urban area can be divided into two phases of changes in the landscape construction phase(2002-2010)and the landscape re-planning phase(2010-2020).In the stage of landscape construction,the area of woodland landscape increased by 26% and gradually became the dominant landscape in Yan’an urban area.Grassland landscape and water body landscape did not change significantly,and the green space landscape tended to be centralized and regular in the large-scale landscape patch layout.At the stage of landscape re-planning,the landscape area of grassland and woodland was transferred to non-green space landscape by 13.65% and 1.48%,respectively.Green space landscape tends to be scattered and irregularly distributed in small landscape patches.(2)During the period 2002-2020,the area distribution of the green space landscape in Yan’an City is affected by topographical factors and has obvious gradient effects.Green space landscapes are mainly distributed in areas with a slope of ≤45°,of which the area with a slope of 15°-25° is the most distributed,reaching more than 40%,which is a dominant distribution.(3)The changes in the landscape pattern of the green space in Yan’an urban area in the 2002-2020 transect are significantly different in the central and peripheral areas.The urban fringe area has steep slopes and relatively fragile ecological environment.Due to the image of green space protection policies,the green space landscape tends to have a concentrated and regular large patch layout,and the heterogeneity of the landscape is reduced.The central area of the city is flat and is the main commercial and residential area of the city.The green space landscape is strongly affected by external disturbances and the landscape heterogeneity is enhanced.(4)Yan’an New City has implemented a topographical transformation project with mountain cutting as the mainstay and landfill as a supplement,which has greatly transformed the green space landscape pattern.After the implementation of the project,non-green space landscapes are mainly distributed in mountain-cutting areas with stable geological foundations,and green space landscapes are mainly distributed in landfill areas that are prone to land subsidence and soft geology.The landscape pattern of green space in the fringe area of the new urban area tends to be a centralized and regular large-scale landscape patch layout,and the green space landscape pattern in the central area tends to be a fragmented and irregular small-scale landscape patch layout.(5)In addition to topographical factors,the green space landscape changes in Yan’an City are also driven by economic,policy and cultural factors.On the time scale,the green space landscape pattern is mainly driven by policy and economic factors.On the spatial scale,the region is driven by topographic factors.In the transects and new urban areas,it is not only driven by topography,but also by economic,policy and cultural factors.