Determination of optimum vegetation type and layout for soil wind erosion control in desertified land in North China

Soil erosion due to aeolian processes is one of the most important forms of soil erosion and environmental quality problems in northern China. Vegetation cover in the process of wind erosion can protect the surface soil through a variety of ways to reduce wind erosion, which has long been recognized. However, in the quantitative study of the protective effect of vegetation cover, there are serious deficiencies for a long time. In this investigation, areas of bare flat desertified land utilizing different vegetation measures in the Zhangbei area of Zhangjiakou, China, was selected as the area which is being simulated in the wind tunnel. By using an experimental research method incorporating indoor wind tunnel simulation, the effectiveness and mechanism of vegetation restoration technical measures to prevent and control soil wind erosion are discussed. The main findings from this study are: (1)In the horizontal direction, soil wind erosion sand transport rates under a single vegetation type were in the order of: evergreen coniferous trees>deciduous broad-leaved trees>grasses>shrubs. When vegetation types were combined, soil wind erosion and sand transport rate under a combination of trees and shrubs was the largest, and a combination of trees and grasses measure was the smallest. (2) In the vertical direction, the rate of sand transmission under a single vegetation type was in line with the exponential function relationship with height change; whereas under combined vegetation measures, the soil sand transmission curve had a “C” shape. (3) Different methods of vegetation combination had different effects on the wind erosion rate, when the combination mode was mixed by rows or mixed by groups, minor differences were recorded in the wind erosion rate, and their wind erosion rates were less than those recorded under a mixed pattern between plants. Our results indicate that vegetation structure can be optimized on desertified land to weaken soil wind erosion in arid and semi-arid typical areas, thereby reducing soil dust emissions and protecting land productivity and the atmospheric environment.