| Urban space is the most frequently and violently interacting region between human and land.Its temporal and spatial changes of landscape pattern reflect the process of urbanization.Urban ecological space is a necessary condition for the sustainable development of a region,and the temporal and spatial changes of its landscape pattern are studied.Characteristics,evolution rules and change mechanisms have important theoretical and practical significance for achieving sustainable development and new urbanization in a region.As an important part of urban space,urban ecological space is being increasingly concerned by experts and scholars,and has become an important part of the study of urban issues.In this study,the main urban area of Nanchang City was used as the research area.With the support of RS and GIS technology,five phases of Landsat images were preprocessed using ENVI5.4,and supervised classification was performed using the support vector machine classification method.Regional area of various landscape elements;use the confusion matrix to verify the classification results;extract the urban ecological space landscape element area by ArcGIS 10.5;analyze the temporal and spatial variation characteristics of various landscapes;Finally adopt Fragstats4.2,from the landscape pattern type level index and The landscape level index was used to calculate the landscape pattern index of Nanchang city in two dimensions,and the evolution characteristics of the ecological space landscape pattern in Nanchang city from 1996 to 2016 were analyzed.The main findings are as follows:(1)From 1996 to 2016,the total area of ecological landscape elements in Nanchang City decreased from 918.8 km~2 to 635.8 km~2,a decrease of 283 km~2,and the proportion of decline was 30.8%.Among them,the area of cultivated land decreased the most,reached 255.18 km~2,and the reduction rate reached 34.8%.In the past 20years,the total area of ecological space landscape elements in Nanchang City showed a downward trend,and the decline rate accelerated.From the internal perspectives,the area where the landscape elements of the ecological space have decreased significantly is Qingshan Lake District(60.94 km~2),Jingkai District(49.16 km~2),Xiaolan Industrial Park(34.32 km~2),High-tech Zone(24.66 km~2),and Mi Town(22.48 km~2)and Honggutan New District(16.86 km~2).(2)From the perspective of the transfer of different types of land use,the transfer of urban and rural residents'land and cultivated land has the most obvious change.Urban and rural residents'land use is mainly transferred to,and cultivated land is mainly transferred out.Among them,the conversion of cultivated land to urban and rural residents has achieved the largest amount of land use,reaching 216.98 km~2.The conversion of forest and grassland to urban and rural residents covers an area of 17.68km~2.The conversion of water areas to urban and rural residents covers an area of 8.22km~2.The arable land was mainly transferred out,which was transferred to 216.98 km~2of cultivated land,28.33 km~2 of grassland,15.68 km~2 of water area,and 50.79 km~2of unused land.(3)According to the analysis of landscape types and landscape level indices,the heterogeneity of the ecological space in Nanchang City decreased,the fragmentation degree continued to increase,and the dominance of urban ecological space also declined,resulting in a decline in the stability of the ecological environment and ecological space in Nanchang City.From the landscape type index,the number of patches in the ecological space of Nanchang City decreased,the proportion of landscape types decreased,the number and density of plaques increased,the dominance of plaques decreased,and the shape of plaques became more complex.The degree of concentration decreased.From the landscape level index,the number of patches of landscape elements in Nanchang increased by 5578,an increase of 2.39 times;the density of plaques increased from 4.0724 to 9.7316;the shape index of landscapes increased from 26.7662to 47.4183;the spread of landscapes was 65.9737 It dropped to 48.6931;the connectivity of the landscape decreased from 99.7181 to 99.3315;the Shannon diversity of landscape increased from 0.8807 to 1.2850;the degree of aggregation of landscape decreased from 95.3319 to 91.3982. |
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