| The northern part of Jilantai Salt Lake is located at the junction of the three major deserts of Ulan Buhe,Tengger and Yamarek.This area is the main source of sandstorms in China.The damage of wind and sand seriously restricts the exploitation and utilization of salt lake resources.This paper takes the Jilantai Salt Lake protection system as the research object,analyzes the distribution of vegetation in different parts of the protection system through the method of field location observation and indoor analysis;investigates the vegetation coverage and diversity of different parts of the protection system;determines the different protection systems The wind speed and sand transport status to the ground near the ground under different wind positions,while monitoring the sand transport,dust fall and surface erosion conditions of different parts of the protection system month by month;and collected surface sediments from different parts of the protection system,and analyzed the mechanical effects of wind-sand activities on the surface sediments.The influence of composition;reveals the law of wind speed change in different parts of the protection system and the movement of sand flow during the year;discusses the effect of different parts of the protection system against wind and sand and the effect of sand blocking in the year.The results are as follows:(1)The effect of wind and sediment prevention of Jilantai salt lake protection system is northwest wind direction > southwest wind direction > northeast wind direction.Attenuation rate of wind speed from moving sand ridge to the center of salt lake increased first and then decreased,and reached the highest(85 % – 95 %)in shelter belt.The sediment transport of the protective system is 83.891 % – 91.793 % lower than that of the mobile sand ridge,and more than 50 % of the sediment transport is mainly concentrated in the 0 – 10 cm height.(2)Seasonal variation had little effect on the sediment transport flux in the shelterbelt,but had a great effect on the sediment transport flux above 50 cm height from the shrub to the center of the salt lake,and the sediment in the region was mainly dominated by the transition.The sand-blocking effect of the protection system was the best from July to December,and the sediment flux was reduced by 80 % – 90 % compared with the flow ridge.The dust retention of the protective system was mainly concentrated in August to October,and decreased with the increase of vegetation coverage.The dust retention was reduced by 11.520 % – 55.832 % compared with that of the mobile sand ridge as a whole,and it was dominated by regional and local substances.(3)The protective effect of the protection system on soil wind erosion is affected by the vegetation growth season.The surface erosion intensity is mainly slight wind erosion in May-June and October-November,and mainly wind erosion in July-September.The grain size of surface sediments in the protective system decreased gradually from the mobile sand ridge to the center of salt lake,and the contents of coarse sand and extremely coarse sand decreased,while the contents of silt,fine sand and extremely fine sand increased gradually.The overall sorting of soil particles is good,the average particle size is large,the particle frequency distribution curve is broad and flat,and the soil quality is significantly improved.(4)Vegetation coverage was significantly positively correlated with wind volume,clay and silt content(P < 0.01).It was significantly negatively correlated with sediment transport flux(P < 0.01),and significantly negatively correlated with soil wind erosion(P <0.05).It shows that with the increase of vegetation coverage,the sediment transport flux decreases gradually,and the soil changes from wind erosion to wind accumulation,which increases the clay content of soil silt and decreases the sand content. |
