关键词: 防风固沙功能, 修正风蚀方程模型, 土地利用变化, 民勤县

Abstract: Based on land use data from five periods between 1980 and 2020 in Minqin County, we estimated the wind prevention and sand fixation (WPSF) substance amount by using the Revised Wind Erosion Equation (RWEQ) model, and analyzed the impact of land use changes on WPSF functions with the support of GIS. The results showed that: (1) Over the past 40 years, the land use pattern of Minqin County had undergone significant changes. Urbanization had accelerated gradually, the area of deserts and bare land had decreased, and desertification had been brought under control. The area of farmland first increased and then decreased. The area of grassland had gradually recovered after experiencing degradation, and the area of forest had expanded steadily. An ecological barrier dominated by farmland, forest and grassland had formed. (2) The WPSF function of Minqin County consisted of the quantity of WPSF materials and the retention rate of WPSF. Temporally, the total quantity of WPSF materials first increased and then decreased, while the retention rate of WPSF kept rising, with a significant increase after 2000. Spatially, the quantity of WPSF materials showed a distribution pattern of “higher in the north than in the south, and higher in the east than in the west”. The retention rate of WPSF presented a distribution pattern of being higher inside the oasis than outside the oasis. (3) There were significant differences in WPSF function across different land use types. Grassland, as the dominant vegetation type, played a major role, while farmland and forest exhibited higher retention rates. Although deserts and bare land contributed large amounts of WPSF substance, their retention rates remained low. Land use transitions from desert and bare land to grassland and shrubland significantly enhanced WPSF functions, whereas degradation from grassland to desert or bare land and from shrubland to desert induced functional decline. Therefore, particular attention should be paid on grassland desertification and the degradation of forest plantation. The overall improvement of sand fixation in Minqin County depended not only on forest expansion but also on the integrated management of multiple ecosystems such as grasslands. Ecological restoration should follow the principle of “growing grass where it is suitable for grass, leaving land fallow where it is suitable for fallow, and planting trees where it is suitable for forests”.

Key words: wind prevention and sand fixation function, revised wind erosion equation, land use change, Minqin County