宜兴市县域尺度生态安全格局模拟研究

Simulation of ecological security pattern at county level:a case study of Yixing

采用InVEST 3.8软件中Water Yield模块、水土流失方程RUSLE模型、土壤风蚀模型方程(RWEQ)等分别评估宜兴市水源涵养、土壤保持、防风固沙和固碳释氧4项生态系统服务功能。针对生态系统服务功能评价结果首先进行热点分析,提取宜兴市的生态源地。然后选取高程、坡度等10个生态源地扩张阻力因子评价宜兴的生态扩张阻力水平。最后采用基于源汇理论的最小累积阻力模型(MCR)模拟构建县域尺度的宜兴市生态安全格局。结果表明:(1)宜兴市水源涵养量分布区间为213 mm—1594 mm,土壤保持量分布区间为11562.28 t·hm^(–2)—268034.28 t·hm^(–2),防风固沙量分布区间为0.54 kg·m^(–2)—11.6 kg·m^(–2),固碳释氧量分布区间为502.82 t·hm^(–2)—1321.83 t·hm^(–2)。生态源地主要集中分布在宜兴市南部的天目山区域、东部的太湖水域和北部的瀛湖水域、中部的东汍、西汍和大溪河水域。(2)生态扩张阻力水平从低到高4个等级的面积分别占宜兴市总面积的53.13%、23.50%、15.07%和8.30%。低阻力等级区相对连接成片,位于东部太湖区域、南部天目山区域、中部东、西汍湿地区域。较低阻力等级主要沿低阻力等级带区呈环状分布。中、高阻力等级地区主要分布于人类活动相对剧烈的农业生产、居民生活区。(3)模拟构建了“一脉、三湖、两纵、五横、十三核”的宜兴市生态安全格局。与现有生态红线划定范围相比模拟补充的生态廊道和生态节点有益于连接破碎的生境,形成完整的生态网络格局。

In this paper,the Water Yield module of InVEST 3.8,the soil erosion equation model(RUSLE)and the soil wind erosion model equation(RWEQ)were used to estimate the four ecosystem service functions of Yixing,including water conservation,soil conservation,wind prevention and sand fixation,carbon fixation and oxygen release,respectively.Then,10 resistance factors such as elevation and slope were selected to evaluate the resistance level of ecological expansion in Yixing.Finally,the minimum cumulative resistance model(MCR)based on the source sink theory was used to simulate the ecological security pattern of Yixing at county scale.The results showed that:(1)the range of water conservation capacity was 213 mm-1594 mm,the range of soil conservation capacity was 11562.28 t·hm^(–2)-268034.28 t·hm^(–2),the range of wind break and sand fixation capacity was 0.54 kg·m^(–2)-11.6 kg·m^(–2)and the range of oxygen release capacity of was 502.82 t·hm^(–2)-1321.83 t·hm^(–2).The ecological sources were mainly distributed in the Tianmu Mountain in the south,Taihui Lake in the East and Yinghu Lake in the north,Dongwan Lake,Xiwan Lake and Daxihe River in the middle.(2)The resistance level of ecological expansion from low to high accounted for 53.13%,23.50%,15.07%and 8.30%of the total area of Yixing City,respectively.The low resistance level area was relatively concentrated in the Eastern Taihu Lake area,the southern Tianmu Mountain area,and the eastern and Xiwan wetland areas in the middle.The lower resistance level was mainly distributed along the low resistance level zone.The middle and high resistance level areas were mainly distributed in agricultural production and residential areas where human activities were relatively intense.(3)The ecological security pattern of“one vein,three lakes,two vertical,five horizontal,and thirteen cores”was constructed in Yixing.Compared with the planned ecological redline,the additional ecological corridors and ecological nodes were beneficial to connect the broken habitats and form a complete ecological network pattern.