Research On The Influence Of Sandy Land Improvement And Wind Erosion By Different Vegetation In The Southern Margin Of Horqin Sandy Land

Horqin sandy sand is China's largest in the eastern part of Inner Mongolia,also is one of the most serious desertification cities.In order to comprehensively analyze the effect of different vegetation on sandy soil and wind erosion control.This study selected the south edge of Horqin sandy land of pinus sylvestris forest,Caragana forest,green bristlegrass and bare sandy land(as control),four typical sites as the research object.The effects of three vegetation types on wind speed and wind erosion are studied by analyzing the physical and chemical indexes.The results are as follows:(1)Effects of three vegetation on soil physical indexes of sandy land:Compared with the bare sand,the three kinds of vegetation have some improvement on the soil physical properties.The soil moisture content of Caragana korshinskii and Pinus sylvestris var.Mongolica is poor,and the water content in the depth of lm is only 2.1%and 2.6%,which is lower than that of bare sand.While the grass carp grass to the best water retention,1m depth of water content reached 7.4%.By analyzing the soil physical indexes of 0?30cm depth,the soil bulk density in the three vegetation plants is lower than that in the bare sand land.The water holding capacity and field water holding capacity of Setaria viridis are the highest,followed by Caragana korshinskii and Pinus sylvestris var.Mongolica.And the highest water holding capacity of Caragana korshinskii forest is the highest,followed by the steppe grassland and the Pinus sylvestris forest land.(2)Effects of three vegetation on soil organic matter content in sandy land:Different vegetation plays a role in improving nutrient content in sandy land compared with bare sand land.Sandy Soil organic matter contents of Pinus sylvestris var.Mongolica,Carassius auratus and Caragana korshinskii in the range of 0?100cm changed with the depth,the highest organic matter in the surface layer;the deeper,the lower.The results showed that there are significant differences in the contents of organic matter between the soils of 0?20cm,20?40cm,40?60cm,60?80cm and 80?100cm.Each layer of organic matter content from large to small are followed by Caragana,Pinus sylvestris and naked sand.From the vertical section,the rate of decreasing of organic matter content in the sandy land of different vegetation is different.The decrease rate of Setaria is the fastest,followed by Caragana korshinskii and Pinus sylvestris,the lowest rate in bare sand is the slowest.During August to October,the content of organic matter in each soil layer changed with time.From the first half of August to the second half of August,the organic matter in each soil layer of Pinus sylvestris var.Mongolica,Setaria viridis and Caragana microphylla decreased with time,and bare sand land decreased stably.From the first half of October to the second half of October,the organic matter content of each soil layer of sand land increased with time.(3)Effects of three vegetation on surface wind speed and wind erosion:The surface range of 0?200cm,the surface wind speed increased with the height of the rapid increase.In the range of 0-200cm,the wind speed of each of the four test sites is from the largest to the following:naked sand>Setaria viridis>Pinus sylvestris>Caragana korshinskii.Compared with bare sand,the greater the impact of the lower vegetation on wind speed,with the increase in the height of the effect of gradually reduced.The change of sediment transport rate with the height of the four regions is similar to the decreasing trend of the negative power function.According to the characteristic value ? of wind and sand flow,it is concluded that the sand movement mode of the Caragana korshinskii area is mostly creep and jump,while the sand movement mode of the bare sand land is dominated by jump and suspension,and Pinus sylvestris var.Mongolica and Setaria viridis is dominated by the transition.By measuring the annual emissivity,it can be concluded that the wind erosion occurred in the bare sand and Setaria in the year,and the annual erosion amount is 5.56cm and 0.81cm respectively;Caragana korshinskii and Pinus sylvestris var.Mongolica have accumulated in the year,with annual deposits of 3.18cm and 0.36cm,respectively.The conclusion is that Caragana korshinskii has played a very good effect on the control of wind erosion,while the control effect of Pinus sylvestris is more general.