School of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing, 210093, People's Republic of China.
Environ Monit Assess. 2010 Dec;171(1-4):457-70. doi: 10.1007/s10661-009-1291-0. Epub 2010 Jan 8.
Urbanization produced significant landscape changes throughout the world. China has been experiencing accelerated urbanization during the past decades. Rapid land use/land over conversion occurred nationwide in urbanization, manifesting noteworthy characteristics of landscape dynamics. In this study, we investigated the spatial differentiation in settlement change rates among 1-km(2) land units in the Nanjing metropolitan region, a representative rapidly urbanizing region in China. Remotely sensed detection using Landsat TM data of 1988-2006 showed that settlement increase, termed as positive growth (PG), was predominant in the study area; while settlement decrease, termed as negative growth (NG), also had a considerable proportion, which was mainly attributed to the increase of green lands and the shrink of rural settlements. Along the urban-rural gradient, PG and NG showed similar mono-peaked patterns. The urban fringe zone with a consistent width of about 4 km was identified as the hot zone of both PG and NG over the three unequal periods. For both PG and NG, high-rated changes tended to exhibit more aggregative patterns along the gradient in the urban fringe zone. Settlement changes showed apparent anisotropy across directions. The directional distribution of PG was significantly negatively correlated to the topographic variables, suggesting that the mountains constrained urban expansion in an "area-weighted inverse-distance power" form. Significant correlation between PG and NG in a time-lagged manner showed the "increase-decrease" fluctuation occurred in settlement changes, reflecting the "urban expansion-land reconfiguration" process in rapid urbanization in Nanjing.
城市化在全球范围内产生了重大的景观变化。过去几十年来，中国经历了快速的城市化进程。在城市化过程中，全国范围内发生了快速的土地利用/土地覆被转换，表现出显著的景观动态特征。在本研究中，我们调查了中国典型快速城市化地区——南京大都市区 1km(2)土地单元的定居点变化率的空间分异。利用 1988-2006 年 Landsat TM 数据的遥感检测表明，定居点增加，称为正增长（PG），在研究区域中占主导地位；而定居点减少，称为负增长（NG），也有相当大的比例，主要归因于绿地的增加和农村定居点的减少。沿城乡梯度，PG 和 NG 表现出相似的单峰模式。确定了约 4 公里宽的城市边缘带为 PG 和 NG 的热点区域，在三个不同时期均如此。对于 PG 和 NG，高评级的变化在城市边缘带的梯度上往往表现出更聚集的模式。定居点的变化表现出明显的各向异性。PG 的方向分布与地形变量呈显著负相关，这表明山区以“加权逆距离幂”的形式限制了城市的扩张。PG 和 NG 之间以时间滞后的方式存在显著相关性，表明定居点变化中发生了“增加-减少”波动，反映了南京快速城市化中的“城市扩张-土地再配置”过程。
