Analyzing The Spatial Distribution Of Public Green Spaces In The Central City Of Shanghai In Terms Of Environmental Justice

Public green spaces(PGS)offer a series of social,environmental,ecological,aesthetic and health benefits to urban residents,and thus positively contribute to urban quality of life and social sustainability of cities.However,some relevant studies on environmental justice found,in most cases,PGSs are unequally distributed across the city.The inequities of PGS provision will impair residents' welfare as well as urban sustainability.At present,equity studies on PGS provision in China's megacities are still rare.Moreover,less is known on equity status of PGS provision to children,the elderly and other social vulnerable groups.In the course of building into an ecological city,Shanghai still faces many difficulties and challenges in PGS construction.This paper is based on "people's livelihood science and technology support program(15DZ1203606)of Shanghai Science and Technology Commission".Taking the Central City of Shanghai as the study area,this research evaluates PGS accessibility and further analyzes whether PGS distribution is fair to social vulnerable groups.The main conclusions are as follows:1.PGS service area ratio under different distance thresholds was calculated by using buffer analysis.PGS service area ratio increased with the increase of distance threshold,and reached a value of 95.2%at 1200m walking distance,covering the vast majority of residential areas.PGS service area ratio gradually decreased away from the city center.PGS service area ratio of Puxi was slightly higher than that of Pudong.2.The Gaussian-based two-step floating catchment area method was used to calculate PGS accessibility.In general,PGS accessibility of Pudong is better than that of Puxi.Low PGS accessibility was observed within the Outer Ring Road of Puxi and in some sub-districts of Pudong.PGS access is better in sub-districts near the northern Outer Ring Road,in the southwest and southeast of the study area.PGS accessibility is obviously higher in Xinjiangwan City,Waigaoqiao Free Trade Zone,Chengjiaqiao Street and Caohejing New Technology Development Zone.3.PGS accessibility was found associated with several social characteristic variables.Factor analysis abstracted three main factors which generally described the variation of social-spatial structure,namely "urbanization development level","socioeconomic status" and "family composition status".Statistics on sub-district groups according to factor scores revealed disparities in PGS accessibility pertaining to social-spatial structure.PGS accessibility was lower in sub-districts with higher urbanization development level;Sub-district group with lowest socio-economic status had best PGS access;Sub-district group with the overall highest percentage of children,married population and family households had best PGS access.4.Children,the elderly,the unemployed,low-educated population and poor-conditioned dwellers were selected as the main social vulnerable groups this study focused on,and an indicator "Comprehensive Demand Index of Vulnerable Groups(CDIVG)" was developed.Sub-districts with high value of CDIVG were mainly located near the Outer Ring Road,as well as near the Huangpu River in some sub-districts of Yangpu District,Hongkou District,Zhabei District,Jing'an District,Luwan District and Huangpu District.5.Man-Whitney U test found significant distribution differences of the elderly,the unemployed and poor-conditioned dwellers based on PGS accessibility.Results of"Equity Performance Index" further confirmed that PGS accessibility of the elderly,the unemployed and the poor-conditioned dwellers was lower than the average PGS accessibility of the whole population.6.The univariate treatment of LISA(Local Indicators of Spatial Association)was used to outline the spatial association modes between the distribution of social vulnerable groups and PGS accessibility.A pattern of poor PGS access combined with high proportion of the elderly or the unemployed was discerned in some neighborhoods of Yangpu District,Hongkou District,Zhabei District,Putuo District,Luwan District and Huangpu District.PGS accessibility was low in some neighborhoods of Hongkou District,Zhabei District and Putuo District,while the proportion of low educated population or poor-conditioned dwellers was relatively high.A pattern of poor PGS access combined with overall high PGS demand of social vulnerable groups was discerned in some sub-districts of Baoshan District,as well as within the Inner Ring Road in some sub-districts of Yangpu District,Hongkou District,Zhabei District,Luwan District and Huangpu District,indicating potential problems of environmental injustice.The findings could be used as a reference for future PGS planning,management and decision-making.