长沙都市区生境质量对城市扩张的时空响应

生境质量是评价生态环境的重要指标,掌握其对城市扩张的时空响应规律,有助于提升都市区城乡规划质量和生态管控的合理性。本文在运用InVEST模型对长沙都市区1995-2015年生境质量时空演化的基本特征进行分析的基础上,利用缓冲区由内向外逐层剖析,探讨长沙都市区近20年来城市扩张格局及其对生境质量的影响。结果表明：①长沙都市区建设用地面积从170.26 km²增至487.19 km²;三环线以内建设用地快速扩张,从三环线起向外扩张逐渐放缓;②生境质量中等及以上的区域占比从1995年的43.49%下降到2015年的27.22%,生境质量平均值则相应地从0.46下降到0.31,且退化最明显的区域从核心外围区(5-10号缓冲区)外移到三环线附近(10-15号缓冲区);③各圈层建设用地扩张强度与生境质量变化之间存在显著的空间负相关性,生境质量变化对城市扩张响应最强烈的区域始终位于核心外围区;④建设用地空间布局零散和几何形态不规则程度的增加加剧了生境质量的退化,并在三环线附近区域(10-15号缓冲区)表现最为明显,应成为未来长沙都市区城乡规划和生态管控的重点区域。

Spatiotemporal responses of habitat quality to urban sprawl in the Changsha metropolitan area

Observing the spatiotemporal responses of habitat quality—an important indicator for ecological environment assessment—to urban sprawl will help improve the quality of urban planning and ecological control. This study respectively analyzed habitat quality of the Changsha metropolitan area from 1995 to 2015 using the InVEST Habitat Quality Model, and revealed the characteristics of the spatiotemporal evolution based on the buffers created by the third ring road. The results show that: (1) The area of construction land in the Changsha metropolitan area increased from 170.26 km² to 487.19 km², which expanded rapidly within the third ring road and gradually slowed outside. (2) Areal proportion of average or above habitat quality levels decreased from 43.49% in 1995 to 27.22% in 2015, and the average level of habitat quality accordingly dropped from 0.46 to 0.31. The most seriously degraded area has shifted from the outer core area (buffer No.5 to No.10) to areas near the third ring road (buffer No.10 to No.15). (3) There is a significant negative spatial correlationship between urban sprawl intensity and habitat quality change across all buffers. The strongest response to urban sprawl in habitat quality change remains in the outer core area. (4) The degradation of habitat quality was exacerbated by the increasing degree of scattered layout pattern and irregular geometrical morphology of construction land and the areas near the third ring road (buffer No.10 to No.15) showed the most significant change. These areas should become the focus area of urban planning and ecological control in the future.