从“增量扩张”到“存量优化”:深圳市景观格局内部动态与优化

From“increment expansion”to“inventory optimization”:internal dynamics and optimization of landscape pattern in Shenzhen

随着城市化的不断推进,以城市扩张为主要特征的土地城市化渐趋于饱和,许多城市开始进入"存量优化"的土地开发阶段。存量优化的土地开发模式改变了城市内部的景观格局,进而影响城市景观的生态过程及功能,但现有的工作主要关注城市的外部扩张,缺乏对城市内部景观动态的研究。以深圳市为例,基于高空间分辨率遥感影像,以地块为分析单元,识别城市扩张、城市更新以及内部填充三种土地开发方式,对比分析不同方式下地块的景观格局变化。研究结果表明:(1)深圳市已进入"存量优化"的城市发展阶段,表现为内部存量变化面积是外部增量变化的2倍;(2)城市更新类型的地块平均植被比例增加3%,提高了人居环境质量,而城市扩张和内部填充类型的地块则表现为植被比例明显下降,平均植被比例分别减少了51%和50%;(3)城市扩张和城市更新具有明显的空间聚集特征,内部填充分布则相对随机。在精细空间尺度上识别了城市扩张、城市更新以及内部填充三种不同景观变化类型,分析了其空间分布特征,为深入理解城市内部景观格局的动态变化提供了新的视角,可为城市生态过程的机理研究和城市规划提供参考与借鉴。

After the rapid urbanization in the last several decades,the land urbanization,which is characterized by urban expansion,has gradually become saturated.Land use strategies have gone through the stage of"inventory planning"in many cities of China.At this stage,urban renewal programs can intensify dynamics of urban land cover,which leads to change the local landscape pattern,and finally has effects on different ecological processes and functions.However,the existing studies mainly focus on urban external expansion and lack understanding of dynamics within the city.In our study,we identified three types of land development modes:urban expansion,urban renewal,and infilling development in Shenzhen based on high-spatial resolution remote sensing imagery.The landscape pattern changes in different modes were compared and analyzed on changing parcel scale.The results showed that:(1)Shenzhen had entered the stage of"inventory optimization"in urban development,showing that the area of internal inventory changes was twice that of external incremental changes.(2)The average proportion of vegetation in urban renewal types had increased by 3%,while that of urban expansion and infilling development had decreased by 51%and 50%,respectively.(3)Urban expansion and urban renewal had obvious spatial aggregation characteristics,and the distribution of infilling development was relatively random.This study identified three different types of landscape changes and their spatial distribution characteristics on a fine spatial scale.It provided a new insight for a deeper understanding of the dynamic changes in landscape pattern within the city,and it would provide a support for the mechanism study of urban ecological process and urban planning.