Study On Spatial Heterogeneity And Influencing Factors Of Urban Greening Coverage In Changsha

The process of urbanization leads to the loss of natural habitat in urban areas,resulting in high spatial heterogeneity of urban vegetation distribution,forming regional differences in vegetation ecological functions,and producing a series of urban ecological problems.In order to enrich and develop urban ecology research in theory and guide urban ecological planning and construction in practice,this study monitored the greening coverage in the built-up area of the Third Ring Road in Changsha by remote sensing;The spatial heterogeneity of greening coverage is quantified on the scale of city,district and county administrative region and urban functional unit;On the scale of urban functional unit,the driving mechanism of natural factors,socio-economic factors and urban form factors on the spatial heterogeneity of greening coverage is quantified.The results are as follows:(1)Taking gaogao-2 remote sensing image as the data source,the remote sensing interpretation generates a 1m resolution land cover classification map(vegetation,water body,impervious surface and bare land).The overall classification accuracy is91.5% and the kappa statistical coefficient is 0.887.(2)The greening coverage rate of Changsha’s core urban area was 46%,and the global Moran index was 0.23,P < 0.001;The greening coverage rate of each district and county administrative area is between 39% ～ 54%;The average greening coverage rate of seven types of urban functional units is between 22% and 35%,and there are great differences in the composition structure between groups.(3)Natural factors,socio-economic factors and urban morphological factors significantly affect the difference of greening coverage in functional areas.The greening coverage rate of residential area has a significant positive correlation with the scale of the community,the average number of floors of buildings,the distance to the main water system,the greening coverage rate in the buffer zone and the number of years of construction,and a significant negative correlation with the building density,plot ratio and the distance to the urban center.All factors account for 47.6%of the variation of greening coverage rate.The variation of 41% of the greening coverage rate of functional units of government institutions can be attributed to the surrounding greening coverage rate,morphological index of functional units,plot ratio,distance to main water systems and building density.The heterogeneity of greening coverage of medical institutions is significantly related to the distance to the main water system,building density and average number of floors.The surrounding green coverage and building density significantly affect the green coverage of the company,accounting for 22% of the variation of green coverage.30% of the variation of green coverage rate of educational functional units is affected by the scale of functional area,the distance to main water systems,the green coverage rate in buffer zone,building density and the distance to urban center.The greening coverage rate of tourist attractions is related to the number of building floors.The greening coverage rate of functional units of traffic facilities is mainly affected by the distance of water system and building density.Urban form is the most important factor affecting the greening coverage rate.Among them,the building density factor shows a significant negative correlation with the greening coverage rate in the six functional units except tourist attractions.There is an obvious interaction between urban form factors and natural factors on green coverage.For example,they jointly explain 11.3% of the variation of green coverage in the functional units of tourist attractions.In residential areas and medical institutions,there is a certain mutual inhibition between socio-economic factors and natural factors on the impact of greening coverage.