Evolution And Scale Effect Of Land Use Landscape Pattern In Shanghai

As the evolution of the urban landscape pattern is closely related to regional economic growth and urbanization,the scale effect is also a key scientific issue in the field of landscape ecology.Therefore,it has important theoretical value and practical significance to explore the temporal and spatial evolution characteristics of the urban land use landscape pattern and its scale effect.As an important economic center and international city in China,Shanghai had experienced rapid urbanization in the past 20 years and has gradually paid attention to the construction of the ecological environment and the sustainable development of the city.Based on Landsat 5/8 images in 1998,2007 and 2017,this thesis took Shanghai as a case study.Firstly,we used GIS spatial analysis methods,landscape metrics,and mathematical statistics to analyze the spatiotemporal evolution characteristics of land use landscape pattern and its driving mechanism.Then,in addition to the conventional first scale domain method,the information loss evaluation model was also combined to comprehensively determine an optimal grain size for the analysis of Shanghai’s landscape pattern characteristics.After,the land use dynamic degree model and space Lorenz curve were used to analyze the changes of land use landscape under the optimal grain size.Finally,based on the grading ring and moving window method,respectively,it was used to study the extent effect of the land use landscape pattern in Shanghai.At the same time,we used the semivariogram model to explore the suitable extent size of its landscape pattern analysis and the spatial variability characteristics.The main results and conclusions are as follows:(1)The characteristics of land use landscape pattern changes were revealed.The dominant landscape types in Shanghai were urban land and cropland,and the area of cropland decreased,while the corresponding urban land area increased,followed by forestland and grassland,which indicates that the area of green space had increased.From the perspective of dynamic changes,cropland was mainly converted to urban land,followed by forestland and grassland.The fragmentation degree of various landscape types in the study area was gradually increasing,whereas that of the shape of landscape patches tended to be irregular.At the landscape level,the diversity and evenness of the landscape increased.At the administrative district level,the characteristics of land use landscape patterns in different municipal districts were different.The level of landscape diversity in the central urban area was lower,while that in the outer suburbs was higher,indicating that it had a superior ecological environment.Population,economic,urban construction,and technological factors were the main driving factors for the evolution of land use landscape patterns.(2)The grain effect of the land use landscape pattern in Shanghai from 1998 to2017 was explored.Land use landscape pattern had obvious scale dependence.Different landscape metrics showed varied responses to grain size changes.According to the characteristics of the grain size response curve,which could be divided into three categories: up and down fluctuating irregular trend,decreasing trend,and no obvious change.The optimal grain size of landscape pattern analysis in the study area was 60 m.With this grain size,the characteristics of land use landscape pattern could be better revealed and ensure as little information loss as possible.Analyze the land use landscape characteristics of the study area under the optimal grain size,it was found that the change of land use types was rapid,the dynamic degree of forest land and grassland were both positive,indicating that the quality of the ecological environment had been improved in the study area.During various municipal districts,the spatial distribution of cropland and urban land was relatively balanced and reasonable,while the distribution of water area,grassland and other land-use was scattered and uneven.(3)The extent effect of the land use landscape pattern in Shanghai from 1998 to2017 was clarified.The landscape pattern of the study area had an obvious extent effect,and the extent response curves of different landscape metrics showed different characteristics as the extent size increased.On the whole,after the extent radius was greater than 54000 m,the extent response curve changed little and remained stable.In addition,the land use landscape pattern in the study area had obvious spatial autocorrelation and variability characteristics.The suitable extent size for Shanghai’s landscape pattern analysis was 4500 m.With this extent size,the spatial variability of the landscape pattern was relatively stable,which could reveal the spatial distribution characteristics of the landscape pattern more accurately.Under the suitable extent,the spatial distribution of landscape patterns varied greatly,the degree of landscape fragmentation and landscape diversity in the central urban area was low,while that in the outer suburb was high and the ecological environment quality was relatively better.There are 28 figures,39 tables,and 183 references in this thesis.