基于生态网络的山水林田湖草生物多样性保护研究——以广西左右江为例

“山水林田湖草是生命共同体”的理念强调生态系统的整体性，反映了自然界各生态系统之间的联系，表明对生态环境的治理要建立在系统论的思想方法上，怎样将“山水林田湖草”的理论思想落实到具体的地区已成为生态保护与修复的关注热点。生态网络的构建不仅可以连接破碎生境，而且能够综合考虑生态系统的各个要素，因此，以广西左右江流域为例，选取保护区作为生态源地，结合最小累积阻力模型（MCR，minimum cumulative resistance）和整体连通性指数（IIC，integral index of connectivity），分析潜在生态廊道的结构组成以及源地重要性，探讨研究区潜在生态网络“山水林田湖草”空间分布。研究结果表明：通过构建生态网络识别出69条潜在生态廊道，但在研究区中部没有可利用的廊道，导致明显的南北阻隔；在51个源地斑块中，仅有3个斑块的重要性指数大于0.2，景观整体连通性较低；通过廊道景观构成的分析发现，耕地占廊道面积比例达20.28%，仅次于自然林地（74.16%），说明耕地对生态网络的构建有重要影响。最后通过廊道与道路的叠加选取9个关键生态节点和23个断裂点，并提出相应的修复和优化对策。研究结果可为广西左右江流域生物多样性保护提供方法和建议，同时作为对“山水林田湖草”生态保护与修复的探索，能够为今后类似研究提供参考。

Biodiversity conservation of mountains-rivers-forests-farmlands-lakes-grasslands using an ecological network: A case study on the Zuoyoujiang river basin in Guangxi Province, China

The existence of mountains-rivers-forests-farmlands-lakes-grasslands systems emphasizes the need for ecosystem integrity and reflects the relationships among natural ecosystems. Thus, ecological protection and restoration methods should be based on the system theory. This study focuses on the ecological protection and restoration of mountains-rivers-forests-farmlands-lakes-grasslands systems in specific regions. An ecological network allows the connection of fragmented habitats and aids the understanding of various elements of an ecosystem. Therefore, using the Zuoyoujiang River basin in Guangxi Province, China as an example, this study selected protected areas as ecological sources, analyzed the structure of potential ecological corridors and the importance of ecological sources using a combination of the minimum cumulative resistance and integral index of connectivity (IIC) models, and discussed the spatial distribution of potential mountains-rivers-forests-farmlands-lakes-grasslands ecological networks. A total of 69 potential ecological corridors were identified; however, there were no available corridors in the central part of the study area, which resulted in an obvious north-south barrier. Among the 51 source patches, only 3 patches had an IIC greater than 0.2, and the overall connectivity of the landscape was poor. Analysis of the corridor composition indicated that the proportion of cultivated land was 20.28%, second only to that of natural forest land (74.16%). Thus, cultivated land has a considerable effect on the construction of ecological networks. A total of 9 key ecological nodes and 23 breakpoints were selected through the superposition of corridors and roads, and corresponding restoration and optimization countermeasures were suggested. The results of this study provide insights into biodiversity conservation in the Zuoyoujiang River basin in Guangxi. Further, this study acts as a preliminary exploration for the ecological protection and restoration of mountains-rivers-forests-farmlands-lakes-grasslands ecosystems and will act as a reference for such studies in the future.