城市核心建成区对邻近新增建设用地影响研究——以长江三角洲为例

为探究城市核心建成区对邻近建设用地增长的影响机制，选取1990~2015年间长江三角洲77个县级以上市核心建成区10km缓冲区内新增建设用地图斑为研究对象，借助扩展强度、景观格局指数和空间分析等方法分析了图斑的成长特征及扩展模式。结果表明：(1）1990~2015年，各等级城市新增建设用地平均面积处于周期波动上升趋势，与各阶段国家（区域）政策变化密切相关；城市等级越高，核心建成区周边扩展规模越大;(2）随着与城市核心建成区距离的增加，各等级城市新增建设用地扩展强度总体呈下降趋势，景观分离度总体呈上升趋势，扩展强度与距核心建成区距离存在衰减的对数曲线关系;(3）研究时段内，城市扩展模式存在两个明显的阶段性特点：第一阶段是1990~2000年，建设用地的增长主要以内部向心填充式集聚为主的城市化阶段，第二阶段是2000~2015年，建设用地的增长主要以离心边缘式圈层扩散为主的郊区化阶段，此阶段大、小城市的飞地式扩展比例明显提升，中等城市边缘式蔓延保持较高的增长比例。针对城市的不同等级及其发展阶段，政策的引导和政府规划对于土地的合理布局有着重要影响。

Influence of Urban Core Built-up Area on Neighbouring Newly-increased Construction Land of the Yangtze River Delta

To explore urban core built-up area’s influence on construction land growth, newly-increased construction patches from 10km buffer of core built-up area in 77 cities above county level of the Yangtze River Delta were selected as the research object. Characteristics and expansion mode of newly-increased construction land were analyzed through expansion intensity , landscape metrics index and spatial analysis methods. The results showed that:Firstly, from 1990 to 2015, each grade city’ s average area of newly-increased construction land fluctuated in cycle riseand had close relationship with plan of Country or local goverment. Meanwhile, the higher the city grade, the larger the extension scale. Secondly, with the distance increase from core built-up area, expansion intensity of patch samples in each grade city had an overall declining trend andlandscape isolation was on the rise as a whole. Extension intensity kept a decline logarithmic curve relationship with distance from core built-up area. Thirdly, in the research period,there were two obvious stage characteristics of urban expansion mode: Urbanization stage was from 1990 to 2000.the growth of construction land gathered by mainly centripetal infilling type .Suburbanization stage was from 2000 to 2015.The growth of construction land mainly diffused by centrifugal edge-expansion type in spheres structure. Outlying expansion type of large and small cities enhanced significantly. Medium-sized cities maintained a high growth rate by edge-expansion sprawl type. In view of different grade and stage of city development, policy guidance and government planning has important effect to reasonable layout of the land.