| The development of the city is related to the quality of people's life.Nowadays,the rapid growth of urbanization not only has promoted the fast development of society and economy,but also has brought a series of negative effects.Therefore,the research of urban land use / cover is crucial for urban planning.Landscape pattern is the most direct manifestation of land use / cover change.Comprehensive study on the change of regional land use,the spatiotemporal variation of landscape pattern and their driving forces is conducive to the sustainable development of cities.Although urbanization in Shanghai develops rapidly,the study of land use and landscape pattern in this area is still not enough in recent years.As a result,this paper studies the change of land use and analyzes the landscape pattern in downtown Shanghai.With the development of 3S technology,the application of RS and GIS is becoming more and more extensive in the analysis of landscape pattern.In this paper,remote sensing images of Landsat ETM+/OLI in 2001,2009 and 2017 are selected as data sources.The original images are pre-processed by radiation calibration,atmospheric correction,clipping,mosaic,image fusion,image geometric correction,band selection and image enhancement,etc.Strip repair is carried out on the images of Landsat 7 with strip loss in the year of 2009.Based on the processed image data of remote sensing,this paper interprets remote sensing images and conducts field investigations in the studied area.Combined with GIS spatial analysis technology and landscape ecology,this paper studies the landscape pattern and its dynamic changes in downtown Shanghai since the 21 st Century.It also analyzes the causes of landscape pattern changes in downtown Shanghai from three aspects: population,society & economy and policy.Accordingly,it provides a scientific basis for further study on the optimization of urban landscape pattern and the sustainable development of cities.The results show that:(1)Downtown Shanghai has developed rapidly since the 21 st Century,thus farm land has decreased to a large extent and most of them have turned into construction land and green space.In terms of planting trees,area of green space in the central urban area increased by 64% from 2001 to 2017.With the development of urbanization,the area of construction land increased sharply in the years 2001-2009.The area of landscapes increases a lot,while the number of landscapes decreases,because small landscapes were combined into one large landscape.In 2009-2017,as more trees were planted,many small landscapes appeared in the construction land,which makes the number of landscapes in construction land increase.As a result,the fragmentation of landscapes increased,and their locations became more separate from each other.(2)The decline in landscape diversity and evenness in downtown Shanghai from 2001-2009 is mainly caused by the decrease in farm land and the increase in construction land.Overall landscape increasingly is made up of a few landscape types,and the landscape pattern tends to be monotonous.The index declined from 2009-2017.Due to the development of landscape construction,the degree of landscape dominance decreased and the diversity of landscape increased.(3)Principal component analysis(PCA)is used to analyze the driving mechanism of the change of landscape pattern in downtown Shanghai in 2001-2017.Human is the main reason for the change of landscape pattern in the studied area.The growth of population has led to the demand for residential land,and the rapid development of economy has resulted in a large increase in construction land and a decrease in farm land from 2001 to 2009.During this period,due to the regulation of policy,the number of population decreased,the demand for residential land was reduced,and the growth of construction land was slow.The implementation of greening policy ensured the steady growth of urban green area. |
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