南京市景观时空动态变化及其驱动力

选择南京市1995、2000和2008年的土地利用/土地覆盖数据,对其土地利用斑块动态变化与景观斑块的空间稳定性进行探讨。结果表明,全市总体上以耕地、林地和草地的减少,以及建设用地和水域的大幅度增加为典型特征。1995-2000年间耕地、林地和草地面积净减少了12017.2 hm²,2000-2008年间净减少41029.13 hm²;全市的建设用地面积1995-2000年间仅增加了11981.3 hm², 2000-2008年间面积增加了41027.06 hm²。从斑块类型的面积稳定性来看,各种土地利用斑块的空间稳定性都非常高,除了2000-2008年间未利用土地的自身空间保持率为50.66%外,其他土地景观类型的保持率都在90%以上。从不稳定斑块的空间分布看,1995-2000年间,主要集中在南京市的栖霞区、浦口区和江宁区,呈离散分布特征; 2000-2008年间,不稳定斑块一方面呈现出集中连片的分布态势,这在江宁区和栖霞区最为典型,另一方面这种集中分布趋势也扩大到了六合区与高淳县。从不稳定斑块的转化方向看,均以建设用地所占比例最大,两个时段内转为建设用地的不稳定斑块分别占到了不稳定斑块总面积的87.09%和68.46%,其次的转化方向为水域,两个时间段内分别达到了10.61%和23.86%。从景观斑块变化的原因来看,对当地景观斑块稳定性影响最大的主要是人口与经济发展、城市规划的引导和重大的生态建设工程等人为因素。

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 cropland and water body ecosystem. Moreover, it was the human factors that posted the most significant effects on the area and the stability of patches including population increase, economic development, urban planning strategies. From 2000 to 2008, the population increased from 544.89×104 to 624.46×104, and the GDP from 1021.3×10⁸ to 3814.62×10⁸, all of this changes exerted prodigious effects on urban development of Nanjing city. At the same time, there are three major ecological construction engineering were implemented which led the the area of forest increased from 7.71×10⁴ hm²(2000) to15.33×10⁴ hm²(2008).