The Research On Landscape Pattern Evolution In The Process Of Urbanization In Karst Mountainous Area

Urbanization is a natural historical process which contains the development of the industrialization,the agglomeration of non-agricultural industries in cities and the concentration of rural population to cities.It is an objective trend of the development of human society and an important symbol of the modernization of the country.City is the most dramatic area of land use and land cover change.With the acceleration of urbanization process,the contradiction between urban construction and the protection of farmland,woodland,water or other landscape becomes more and more intense.How to understand the landscape pattern,such as land,water,farmland,grassland and woodland,changes and environmental effects in the process of urbanization are the focus and hot spot,especially in the karst mountain areas,which has a fragile ecological environment and complicated landscape pattern.Guiyang city is` located in the core area of the central region of the karst typical region in East Asia,which has the largest distribution area of the global karst geomorphology and the most complete karst type.It is very typical and representative.Therefore,taking Guiyang as an example,it has a very high reference value to solve the environmental problems caused by the optimization of urban planning layout and the change of urban landscape pattern in the process of urbanization in studying landscape pattern evolution in karst mountain areas.Taking Guiyang as an example,by analyzing the relevant research results at home and abroad,combining qualitative and quantitative analysis,spatio-temporal analysis and modeling,with the support of software such as ENVI5.1,Arcgis10.2,Fragstats4.2 and IDRISI17.0,the characteristics of land use and landscape pattern in the spatial and temporal scale of Guiyang in recent years are analyzed.The results of the study show that:(1)In the process of urbanization in Guiyang,the construction land is increased,the area of framland,woodland and grassland are reduced,and the area of water area has little change,which is consistent with the continuous promotion of urbanization in Guiyang.The increased area of construction land mainly comes from farmland,grassland and woodland.The decrease of farmland was the largest,which mainly turned into construction,the increment mainly transferred from grassland;the area of woodland changed little,which most turned out to be the construction.The most increment of woodland was come from grassland;the frequency of grassland change was the highest,and it was in dynamic transformation with woodland,farmland and grassland.(2)The urbanization process in Guiyang City is divided into three stages.before 2000 is the period of low speed expansion,besides the city center,the space features of other construction sites in Guiyang were disordered and scattered.The 2000-2010 year was the period of rapid development of urbanization,and the built-up area gradually developed from sporadic point to strip,and the District of Guan Shan Lake became the Second Development Center of Yang City.the 2010-2015 year is the rapidest development period of the urbanization process of Guiyang city.The built-up area extends from strip to large area,which is characterized by large aggregation and small dispersion.(3)From the time scale,the landscape features of Guiyang have not changed obviously before 2010;in the later period of urbanization,the human activities are frequent,and the landscape ecological characteristics of Guiyang are developing towards entropy,the landscape diversity becomes larger,the landscape heterogeneity is enhanced,and the landscape diversity and landscape heterogeneity are increasing with the continuous promotion of urbanization.In the process of urbanization,the fragmentation of water landscape is the highest.With the continuous promotion of urbanization,the fragmentation gradually decreases;the fragmentation of farmland,woodland and grassland is basically unchanged in the early and middle stages of urbanization,and the fragmentation increases fastest in the later stage of urbanization,and the fragmentation degree of the construction is continuously reduced in the process of urbanization.Straight is the dominant landscape in Guiyang.In the later stage of urbanization,the dominance of construction land exceeded grassland for the first time,and gradually developed to the optimal landscape.(4)From the location scale,in early and middle stages of urbanization the dominant landscape in the central urban area is woodland.In late period of urbanization,the construction land takes the place of woodland become the dominant landscape.the cultivated land in the central urban area has the strongest degree of crush,and the other landscape fragmentation in the area except the farmland is reduced;With the development of urbanization the landscape diversity,heterogeneity and evenness of the central urban area are all decreased.The construction area of suburban changed greatly and has gradually become the most important city development center in Guiyang.The dominant landscape of the suburban junction is cultivated land in the early and middle stages of the urbanization process,and the woodland becomes the dominant landscape in the late stage of urbanization.The dominant landscape in the suburb is woodland and the cultivated land is second.It is known that the process of urbanization in the suburbs started late,gradually started after 2000,and the urbanization process increased obviously after 2010.In the process of urbanization,the landscape diversity,heterogeneity and fragmentation in suburban and suburb were increased.The central urban area should draw lessons from the suburban and suburb.(5)From the change characteristics of the total perimeter and the landscape shape index in the different urbanization stages of the urban center,the suburban and the suburbs of Guiyang,it is known that with the continuous advancement of the urbanization process,various landscape shapes tend to be regular.