北方防沙带典型县域生态安全格局研究

生态安全格局构建是生态安全屏障建设和防风固沙能力提升的关键。北方防沙带是我国主要的风沙策源区，也是防治沙化的核心区，具有干燥少雨、植被稀疏、沙漠广布等生态特征，针对如何在北方防沙带构建适宜的生态安全格局做了研究探讨。以位于北方防沙带中部的民勤县为研究案例，基于“基质脆弱、廊道稀疏、斑块零碎”的景观基底和风沙源扩散机制，提出面向北方防沙带防风固沙能力提升的“控风源-堵风口-筑风廊-优网络”风沙阻隔型生态安全格局构建逻辑范式。结果表明该范式有助于深入了解北方防沙带生态安全问题与生态安全维持机制，可为其他干旱区生态安全格局构建提供新思路。

Ecological security pattern of typical counties in northern sand prevention belts

Construction of ecological security pattern is the key to the construction of ecological security screens and the improvement of wind prevention and sand fixation ability. Northern sand prevention belts are the key ecological function areas in the national ecological security strategy pattern of "two screens and three belts", the main source areas of aeolian sand, and the core areas of desertification control in China. Northern sand prevention belts have special landscape ecological bases such as "fragile substrate, sparse corridors and fragmented patches", so it is not suitable to construct traditional ecological security pattern for ecological connectivity. There is no mature theory and method on how to build appropriate ecological security pattern in the northern sand belts, this paper has carried out some preliminary discussion in this regard. Minqin County, located in the middle of the northern sand prevention belts, was taken as a case study. Based on the diffusion mechanism of sandstorm source, anchoring sandstorm source land, building green sand-blocking key points, connecting sand-blocking corridor and optimizing ecological safety network, the paper proposed a logical paradigm for constructing sand-blocking ecological security pattern of "wind source identification-blocking node-wind corridor-constructing network". Based on the multi-source data of land cover, meteorological stations and soil in Minqin County in 2018, RWEQ model, minimum cumulative resistance model and cost path model were used to identify and analyze the total area of sandstorm source in the study area of 3,136 km², which mainly consists of sandy land and other grassland, and presents a block distribution. There are 43 key points for sand control, including the key ecological nodes with relatively good ecological environment and the key obstacle points with relatively poor ecological environment, which are mainly distributed at the inflection point and crossing point of sand source diffusion path. A total of 41 windbreak sand-fixing corridors, totaling 627.4 km, are connected to the key nodes of sand control and distributed in the north of Hongshagang Town and Donghu Town, perpendicular to the diffusion path of sand source. The ecological security optimization pattern of "7 centers, 36 points and 14 corridors" was constructed from aspects of improving the functions of corridors and nodes, constructing the hierarchy system and ecological connectivity, combined with the actually regional conditions. The results show that the paradigm is helpful to understand the ecological security problems and maintenance mechanism of ecological security in northern sand prevention belts, and can provide a new idea for ecological security pattern construction in other arid areas.