长江经济带城市扩张的时空特征与生态响应

量化识别城市扩张在不同发展阶段的时空特征，有助于从宏观上认知城市扩张态势，理解城市化的生态响应。以Landsat TM/OLI影像为数据源，分析了近30a（1986~2016年)长江经济带3个省级城市和4个地级市的城市扩张，包括建设用地的时空变化和扩张模式，以及扩张的生态效应。结果表明：(1)建设用地扩张量在过去30a呈线性递增过程，平均扩张速率在2006~2016年降低，表明建设用地由增量扩张向存量开发转型，但地级市的转型滞后于省级城市;(2)蔓延式扩张比例下降而填充式扩张和飞地式扩张不断增加，说明城市扩张模式由粗放蔓延型向紧凑集约型转换;(3)建设用地从快速扩张到稳定扩张的过程与植被覆盖从退化到管控的过程一致，印证了建设用地扩张与植被覆盖度的时空关联性。同时，建设用地扩张导致的生态系服务价值负值不断增加，较大幅度的降低了生态系统服务总价值。面临城市扩张进程中出现的植被覆盖退化和建设用地生态系统服务负值过大的问题，合理而有力的规划政策实施在未来城市发展中尤为重要。

Spatio-Temporal Characteristics and Ecological Response of Urban Expansion in the Yangtze River Economic Zone

Quantifying the Spatiotemporal characteristics of urban expansion is necessary to identify the process of urban expansion and understand the ecological response of urbanization. Based on Landsat TM/OLI images, this paper analyzed the urban expansion of 3 provincial cities and 4 prefecture-level cities in the Yangtze River Economic Belt in recent 30 years, including the analysis of the Spatiotemporal change and expansion mode of the construction land, and the ecological effect of the expansion. The results showed that: (1) The urban land has increased linearly over the past 30 years,but the average expansion rate is reduced in 2006-2016 years, which indicated that the urban land is transformed from the incremental expansion to stock development, but the transformation of prefecture-level city lags behind the provincial cities. (2) The proportion of edge expansion is declining, whereas infilling and leapfrog are increasing, which reflected the urban expansion is transforming from extensive rapid expansion to intensive. (3) The process of construction land from rapid expansion to stability is consistent with the vegetation cover from degradation to control, which confirmed the temporal-spatial correlation of construction land expansion and vegetation coverage. The negative value of the ecosystem service value caused by urban land expansion has been increasing, which greatly reduced the total value of ecosystem services. Facing with the problem of vegetation degradation and excessive negative of ecosystem services value, reasonable and effective implementation of planning policies are utmost important in the future urban development.