顾及城郊农田生态服务价值的中心城区生态安全网络重构

针对中心城区日益凸显的农业、生态、城镇三类空间冲突问题,借鉴田园城市理论,创新性地提出一种利用城郊高生态价值农田细化城市生态安全网络,构建"三生"空间协调有序的国土空间格局的方法。利用防城港市遥感影像、国土调查和社会经济数据,在城郊耕地综合评价的基础上,采用评价结果修正的当量因子法评估其农田生态价值。进一步利用InVEST、MSPA及MCR模型初步构建市域生态安全网络,再将高生态价值农田作为临时生态节点完成网络重构,并进行对比分析。以重构的新网络指导中心城区的规划分区优化,并对市域和中心城区两级生态网络要素的空间管控规则及联合管理机制进行了探索。结果表明:(1)防城港市区单位面积农田生态价值为35540元/hm²,高生态价值农田较均匀的环城分部。(2)重构后的网络新增34个临时节点和51条绿带,延长48.425 km,增加808.89 hm²生态源。(3)新网络能有效引导中心城区形成圈层发展结构,较原网络在连通性、有效性、稳定性上均有所提升。研究结果为注重协调发展的国土空间规划背景下区域空间格局优化提供了新的思路。

Reconfiguration of the ecological security network in the central city considering the ecological service value of suburban farmland

In view of the increasingly prominent conflict among agriculture, ecology and urban space in the central city, this paper drew inspiration from the Garden city theory, and proposed a method to refine the urban ecological security network by using the suburban high ecological value farmland, and to construct a coordinated and orderly territorial spatial pattern of "three living" spaces. We utilized remote sensing data, land surveys and socio-economic data from Fangchenggang City, and based on the comprehensive evaluation of the suburban farmland, assess its ecological value using the equivalent factor method, which was modified by the evaluation results. Further we applied InVEST, MSPA, and MCR models to construct a preliminary urban ecological security network, and then chose high ecological value farmland as temporary ecological nodes for network reconfiguration and conducted comparative analysis. Finally, we used the reconstructed new network to guide the optimization of planning zoning in the central city area, and explored the spatial control rules and joint management mechanisms for the two levels of ecological network elements in the city area and central urban area. The results showed that: (1) The ecological value of cultivated land per area in Fangchenggang urban area was 35540 Yuan/hm², and the high ecological value farmland was relatively evenly distributed around the city. (2) The reconstructed network had added 34 temporary nodes and 51 green belts, extended by 48.425 km, and added 808.89 hm² of ecological source land. (3) The new network can effectively guide the formation of a circle development structure in the central city, which had improved connectivity, effectiveness, and stability compared to the original network. The results provided new ideas for the optimization of regional spatial structure under the background of territorial spatial planning that emphasizes coordinated development.