基于综合评价法的洞庭湖区绿地生态网络构建

绿地生态网络对于改善区域生态空间破碎化、生物多样性降低、生态系统服务供需不平衡及保障区域生态安全具有重要意义。本研究以洞庭湖区为例,在3S技术支持下,从生态系统服务功能、潜在生物多样性、形态空间格局的角度综合评价和识别生态源地及计算栅格单元的基本生态阻力;利用夜间灯光指数修正基本生态阻力;运用最小累积阻力模型识别生态廊道;构建加权评价模型,对源地的聚合度、离散度及廊道的生态连接贡献度进行评价;利用结构特征指数对综合网络、“源-汇”潜在网络及规划网络进行对比分析和评价。结果表明: 源地空间分布不均衡,林地、灌丛与水域三者面积之和占源地总面积的95.9%,位于研究区中部的洞庭湖湿地生态风险较高;源地离生态网络系统中心位置越近及到其他源地的平均最小累积阻力越小,聚合及离散的优势越强;高生态质量源地周围的中、高生态质量源地分布越密集,其聚合度、离散度越高;廊道离高生态质量的源地越近,表现为生态连接贡献度越大;林地、灌丛,尤其是河道在自然生态系统与人类社会系统之间起着非常重要的生态连接作用;“源-汇”规划绿道对“源-汇”潜在生态廊道形成了良好补充,与“源-汇”潜在网络相比,综合网络的α、β、γ、ρ指数分别提高123.1%、25.8%、26.2%、74.6%;与“源-汇”规划网络相比,α、β、γ、ρ指数分别提高了190.0%、31.1%、32.5%、114.6%。本研究结果能为洞庭湖区绿地生态网络构建、国土空间规划提供参考。

Construction of green space ecological network in Dongting Lake region with comprehensive evaluation method

Green space ecological network is important for improving the fragmentation of regional ecological space, biodiversity loss, imbalance of supply and demand in ecosystem services, and ensuring regional ecology. With Dongting Lake region as an example, the ecological sources were evaluated and identified, and basic ecological resistance of grid element was calculated from the perspectives of comprehensive ecosystem service function evaluation, potential biodiversity comprehensive index evaluation and morphological spatial pattern analysis with the support of 3S technology. We corrected the basic ecological resistance by night light index, used the minimum cumulative resistance model to identify ecological corridors, and constructed a weighted evaluation model, eva-luated the degree of aggregation and dispersion of the sources, as well as the contribution of ecological connection of the corridors. Furthermore, we compared and evaluated the structural characteristic index of the integrated networks, the potential “source sink” networks and the planning networks. The results showed that the spatial distribution of the sources was uneven, with forest land, shrubland and wetland acounting for 95.9% of the total area. The Dongting Lake wetland located in the middle of the region was at high ecological risk. The closer the source was to the center of the ecological network system and the smaller the average minimum cumulative resistance was to other sources, the stronger the advantages of aggregation and dispersion. The denser the distribution of medium and high ecological quality sources was around the high ecological quality sources, the higher the aggregation and dispersion. The closer the corridor was to the high ecological quality sources, the greater contribution of ecological connection. Forest land, shrubland, especially river played an important role in connecting natural ecosystem and human social system. The “source-sink” planning greenways formed a supplement to the “source-sink” potential ecological corridors. Compared with the “source-sink” potential network, the α, β, γ and ρ index of the integrated network was increased by 123.1%, 25.8%, 26.2% and 74.6% respectively. Compared with the “source-sink” planning network, the α, β, γ and ρ index was increased by 190.0%, 31.1%, 32.5% and 114.6% respectively. The results could provide reference for the construction of green space ecological network and planning of land use in Dongting Lake region.