Research On The Spatial-Temporal Evolution Of Urban Green Space In The Process Of Guangzhou-Foshan Integration

Guangzhou-Foshan,one of the most mature regions in the process of urbanization in China,has rapid growth in urban scale and continuous expansion of urban space.However,eco-environmental problems are becoming increasingly prominent,and the urban environmental carrying capacity is facing serious threats.As the basic element of city,urban green space plays an important role in regulating the urban climate and alleviating the UHI effect.This thesis took Guang-Foshan as the study area,extracted information of urban green space from 2009 to 2020 by using object-oriented classification,and analyzed its landscape pattern and spatio-temporal evolution of urban green space by using transfer matrix,kernel density anlysis and landscape metrics.Finally,this thesis used quantitatively analysis using the GIS-Logistic model and qualitatively analysis to explain the driving mechanism of urban green space change in the study area,and relevant suggestions were put forward for the construction of urban green space in the study area.Following conclusions were achieved:(1)The overall accuracy of the classification results is 85.1%,88.3%,and 93.2%,and Kappa coefficients are greater than 0.80.According to the classification results and the analysis of the proportion of the area,the area percentage of the urban green space of Guangzhou-Foshan and Guangzhou showed a trend of first increasing and then decreasing from 2009 to 2020.In three periods,the green space area of the former was 4897.46 km~2,5428.7 km~2 and 5295.4 km~2,and the urban green space mainly was concentrated in Conghua district of Guangzhou and Gaoming district of Foshan.The green space area of the latter reached its maximum in 2014,at 4275.97km~2.The area of urban green space in Foshan had continuous growth,increasing by125 km~2 totally.The urban green space in the core area of urbanization had significant changes from 2014 to 2020,with an increase of 83.79 km~2.The results of kenel density analysis indicated that the density values of urban green space in the northeast in the core area of urbanization were relatively high in 2009 and 2014,and significantly increased in Tianhe district and Haizhu district of Guangzhou in 2020.(2)The results of transfer matrix indicated that from 2009 to 2020,the main types of land flowing into urban green space in Guangzhou were cropland and construction land,while the outflow direction of urban green space was mainly construction land.The mutual transitation between urban green space,construction land,and cropland in Foshan.The cropland in the core area of urbanization was the main source of expansion of urban green space from 2009 to 2014.The main types of land transferred to urban green space from 2014 to 2020 were construction land and cultivated land,with the transferred areas of 42.55 km~2 and 44.37km~2,and the outflow land mainly refers to construction land.(3)The calculation results of landscape metrics showed that the landscape pattern of urban green space in Guang-Foshan megalopolis and the core area of urbanization changed slightly from 2009 to 2014,and the number of patches increased significantly from 2014 to 2020,the regularity of patches decreased,and the degree of fragmentation increased.The fragmentation occurred in the core area of urbanization and Nanhai district of Guangzhou.(4)The results of the GIS-Logistic model indicated that the increase in urban green space is negatively correlated with slope,DEM,and population change,while positively correlated with GDP changes with the strongest correlation;The decrease in urban green space is negatively correlated with distance from rivers,DEM,precipitation,distance from residential areas,and slope,while positively correlated with temperature with the highest correlation.The qualitative analysis results indicated that urbanization,green engineering,and related policies have a driving effect on the change of urban green space.Finally,some suggestions are put forward for the future construction of urban green space in Guangzhou-Foshan,such as reducing the occupation of urban green space on the basis of the existing spatial pattern,reasonably developing and maintaining ancillary green space and other green space types,and increasing green space investment.