Spatio-temporal dynamics of land use/land cover and its driving forces in Nanjing from 1995 to 2008

It is of great significance both theoretically and practically to describe and understand the dynamics of urban spatial structure for developing optimal urban planning and achieving the healthy urban ecosystem functions. We, hereby, used the land use maps of Nanjing in 1995, 2000 and 2008 to analyze the dynamics of land use patches, stability and the driving forces. The methodology includes the ArcGis tools and social-economic statistics. Finally the recommendations for urban forestry planning of Nanjing were provided thereafter. Overall, the cropland, construction land and forest land of Nanjing were three major landscape patch types and over 50% of the cropland has been the matrix throughout the year of 1995 to 2008. Landscape changes included the area decrease in cropland, forest land, grass land, and the increase in construction land and waters. In addition, the landscape change was getting more rapidly over the time. The area of cropland, forest land and grass land had decreased by 12,017 ha in total from 1995 to 2000, and 41,029 ha from 2000 to 2008. In the meantime, the area of construction land had increased by 11, 981 ha from 1995 to 2000, and 41,027 ha from 2000 to 2008. From the perspective of the stability of the area of landscape patch types, the spatial stability of each land use type was very high. All land use types had a stability rate over 90%, except for the unutilized land with a stability rate of 50.66%, from 2000 to 2008. Using the GIS spatial locating techniques, all the unstable patches and its changing direction were all showed on the map. Based on this information, we found that, the unstable patches were mainly scattered in Qixia District, Pukou District and Jiangning District from 1995 to 2000; and from 2000 to 2008, those patches were more aggregated and connected especially in Jiangning and Qixia districts, and the unstable patches were also aggregated in Liuhe District and Gaochun County. Depond on the GIS satistacs founction, we found that the unstable patches were transformed into the construction land by an area rate of 87.09% and 68.46%, and to the water bodies by 10.61% and 23.86%, respectively, for the two periods. In contrast, the transformation rate in to cropland, forest land and grass land were all below 5%. Our analysis indicated that the climate warming and drying has posted the effects on the landscape changes and thus the quality of the whole urban ecosystem of the city, especial on the forest, grassland croplan