基于生境质量的城市增长边界研究——以长三角地区为例

基于“生态优先”理念,提出一种利用生境质量评估策略的城市增长边界划定方法。结合ArcGIS和InVEST模型,通过综合评估生境自身及其在威胁情境下的质量,模拟各市独立规划、建设用地指标再分配及区域一体化发展的三类建设用地扩张情景,分别划定2024和2034年的长三角地区城市增长边界。结果表明：研究区生境质量总体呈南高北低格局,平均生态系统服务价值密度为10 770.604元/（hm²·a）,高质生境位于西南地区;根据指标再分配及一体化发展情景模拟的2024年研究区建设用地总量分别为10 583.273 km2和10 489.090 km2,2034年达到13 603.535 km2和13 252.370 km2;模拟的建设用地集中在东部沿海地区,并向北部及环杭州湾区域拓展;建设用地指标再分配能从整体上减少建设用地对优质生境的占用,区域一体化发展则能进一步降低城市发展造成的生态压力。

Urban Growth Boundary Based on the Evaluation of Habitat Quality:Taking the Yangtze River Delta as an Example

The world’s natural ecosystem provides products of 15 trillion pounds annually, but with the universal urban expansion caused by economic development, ecological balance is gradually disrupted. Therefore, it’s critical to maintain ecosystem stability in the identification of urban growth boundary, which is regarded as an effective tool to control urban sprawl. However, very few methods, currently, have taken ecosystem into their account. With the concept that “ecology goes first”, this article put forward a method to identify the urban growth boundary based on the evaluation of habitat quality. Using the platform of ArcGIS and InVEST model, two aspects of habitat quality were considered in the assessment: the quality of habitat itself and the quality under threats. As a representative of the former quality, ecosystem service value of each cell was calculated. As to the latter one, InVEST model was used to assess cells’ threatened degree. In the prediction of the amount of future construction land, three scenarios were developed. The first scenario was based on the assumption that cities had separate development and urban planning. The second scenario assumed that in spite of the separate planning, it’s possible to conduct the redistribution of construction land index. The third scenario ignored the boundaries of administrative jurisdiction and regarded the study area as a single. By selecting districts with lower habitat quality as construction land, the simulated urban growth boundary of the Yangtze River Delta in 2024 and 2034 were determined. The conclusions showed that habitat quality in the south of the Yangtze River Delta was overall higher than that in the north and the average density of ecosystem service values was 10 770.6 yuan/(hm2?yr). Habitat with higher quality was located in the southwest area, while the lower one was in the eastern district and Round Hangzhou Bay. By 2024, the predicted quantity of construction land have been to 10 583.27 km2 (scenario 1 and 2) and 10 489.09 km2 (scenario 3), and then have been to 13 603.53 km2 (scenario 1 and 2) and 13 252.37 km2 (scenario 3) by 2034. East coastal area would be the center of construction land, and the northern districts and Round Hangzhou Bay were considered to be the main expansion area. In order to avoid the occupation of construction land on habitats with higher quality as a whole, 9 cities were classified as emigration region of construction land index, and 5 cities were categorized as immigration area, and the left 2 cities were transition regions. Moreover, regional integration of the Yangtze River Delta could also helpfully mollify the contradictions between urban development and ecological protection. Policy recommendations on the identification of urban growth boundary were proposed at the end, while possible innovations and inadequacies of this article were also concluded.