基于空间扩张互侵过程的土地生态安全动态评价——以(中国)苏锡常地区为例

从景观单元水平过程出发,通过采用生态用地和建设用地两种不同源空间扩张互侵过程的方法,提出了以分区形式的土地生态安全动态评价方法。以快速城市化苏锡常地区为研究区域,分别以生态系统服务价值高的水域和林地及建设用地现状为扩张源,生态系统服务价值和生态风险值为阻力赋值依据,在模拟不同生态安全格局水平和城市发展模式的基础上测算互侵结果并进行区划。结果表明:1)不同城市发展模式下建设用地空间扩张随生态用地从底线到满意到理想水平变化呈空间集聚收敛趋势;生态用地呈似圈层状空间集聚趋势。2)城市发展模式对土地生态安全水平具有显著影响;高等级源优先发展模式下土地资源利用更集约。3)将研究区划分为生态核心区(面积占比35.27%)、生态安全区(29.07%)、缓冲区(7.76%)及建设区(27.90%),提出相应土地用途管制措施。探讨了新方法不足和未来研究方向。

A dynamic approach to land ecological security assessment: a case study of Su-Xi-Chang area, China

Land ecological security (LES) assessment is a main focus of LES research. The aim of this study was to develop a dynamic approach to achieve an objective assessment. Su-Xi-Chang area was selected as the study area. Based on the source-sink landscape theory, ecological land and construction land were treated as the source and sink, respectively. The minimum cumulative resistance model was applied to simulate the dynamic changes of these landscapes. The resistance values of the ecological land were obtained from ecosystem service values of different land-use types, whereas those of the construction land were derived from ecological risk values. The spatial expansion and simultaneous invasion of both construction land and ecological land were simulated with ArcGIS software. In the case of ecological land expansion, three scenarios were simulated, i.e., low-, middle-, and high-level LES. In the case of construction land expansion, three urban development models were designed, i.e., metropolitan development in priority (MD), small and medium cities development in priority (SD), and all urban sources development in equilibrium (ED). In the case of invasion, nine scenarios were formed from the spatial overlapping of these two kinds of expansions and their respective scenarios. The study area was zoned into five levels of LES according to the invasion results, i.e., suitable construction (very low), ecologically fragile (low), buffer (middle), ecological security (high), and ecological core (very high) zones. The results of this study showed that:(a) Along with the scenarios of LES ranging from low- to high-level, the expansions of construction land in different development models displayed a significant convergence trend of spatial agglomeration; the modeling of ecological land, however, indicated a trend of circular sprawling from the core to the outward. In the low-level scenario, the percentage of suitable construction zoned land was the highest in the MD model, at 27.90%, and the lowest in the SD model, at 21.59%. In the high-level scenario, the percentage of suitable construction zoned land was the lowest in the MD model, at 9.42%, and the highest in the SD model, at 13.10%. (b) In the same ecological security scenario, the different urban development models displayed different impacts on construction land expansion. In the low-level scenario, the combined percentage of suitable construction zoned land and ecologically fragile zoned land was the lowest in the MD model, at 38.24%, and the highest in the SD model, at 46.03%. In the high-level scenario, the corresponding value was also the lowest in the MD model, at 14.41%, and the highest in the ED model, at 21.20%. (c) Urban development models have significant influence on the levels of LES. Among the three urban development models in this study, the MD model benefitted intensive land use and found the land to be suitable for rapid urbanization, improving the area''s LES from the current level to a higher level. A LES zoning plan was recommended, as well as measures of land-use control. In the plan, the area percentages of the suitable construction, buffer, ecological security, and ecological core zones were 27.90%, 7.76%, 29.07%, and 35.27%, respectively. The developed approach was found to be effective in dynamically assessing LES and beneficial in the differential management of land resources. The dynamic approach investigated in this study highlights the methodology in the optimization of ecological land patterning. Finally, issues on how to improve this developed method and future research directions have also been discussed.