Quantification And Location Stability Of Landscapes On The Urban-rural Gradient:a Case Study In Nanjing Metropolitan Region

Urbanization is a significant aspect of global change. The process of urbanization has a profound impact on ecosystem’s composition, structure, function, etc, changing the landscape pattern of the city and its surrounding areas, thus becoming one of the focuses of ecology research at the present stage. The study of the quantity and spatial change of landscape and its stability characteristics is a vital approach to study urbanization and provides great significances for landscape management.The current research on landscape change mainly focuses on the quantity-related issues of area change of landscape type, conversion degree, and change rate. However, the research is rarely related to the spatial location and the comprehensive information change in the process of landscape change. By calculating the Kappa index, this thesis quantifies the number, spatial location and comprehensive information change from the angles of spatial location and quantity in order to improve the research method of landscape change.Located in the Yangtze River Delta in eastern China, Nanjing has experienced rapid economic growth and urbanization process since the1980s and its landscape change process is highly representative. This thesis is based on the multi-temporal remote sensing data and divides the study area into58grids with the10km×10km grid; the thesis studies the quantity of landscape elements in different locations and spatial location change in landscape during two periods of1988-1998,1998-2008by calculating the Kappa index, exploring the dynamic characteristics of different elements in the landscape and its changes along the urban-rural gradient in order to reveal the dynamic pattern of landscape compostion and spatial structure in the process of urbanization as well as the relative diversity of spatial location and quantity stability of different landscape elements in the process of urbanization. The research results are as follows:(1) The landscape in the study area within the two periods has substantial changes, the changes are even greater in the1998-2008period. The quantity stability of Nanjing’s landscape during the1988-1998is obviously higher than the period of1998-2008, while the stability of spatial location is slightly lower. The main changes in the study area during the period are the accelerated reductions of cultivated land and the continued expansions of settlement land. The quantity stability of cultivated land is higher, but its spatial location stability is lower. Comparatively, the spatial location stability is higher while its quantity stability is much lower. The amount of forest and other land and their spatial stability are relatively low, while both the spatial location and quantity stability of water are relatively higher.(2) Along the urban-rural gradient, the spatial location stability of landscape shows a increasing trend while the quantity stability indicates a upward trend. The quantity stability of landscape in the central urban area which has completed urbanization increases rapidly and its composition of landscape elements and spatial distribution characteristics are stabilized.(3) The spatial location stability of settlement land and cultivated land decreases with the increase of distances from the central urban area, while the quantity stability change is more complex. The quantity stability of settlement land and cultivated land during1988-1998increases with the increase of distances from the central urban area, reaching a peak at about20km from the central urban area and then declines slightly. However, during the period of1998-2008, the quantity stability of settlement land and cultivated land firstly decreases and then shows a increasing tendency, reaching a lowest point at about20km from the central urban area. The Kappa index for the amount of water and forest are rather high along different urban-rural gradients, but their Kappa index for location are quite low. Overall, the spatial location and quantity change of settlement land and cultivated land vary relatively greater along the urban-rural gradient, while the variation of water and forest is relatively smaller along the urban-rural gradient.