Effects Of Different Artificial Vegetation Measures On Soil Properties In Mu Us Sand Land

Mu Us Sandy Land is located in the ecologically fragile zone of semi-arid region in China.Low vegetation coverage and severe wind erosion lead to land degradation in the Mu Us Sandy Land.However,vegetation restoration can effectively inhibit land degradation and improve soil quality of degraded land.Exploring the changes of soil properties under different vegetation restoration is helpful to reveal the evolution process of soil desertification in the Mu Us sandy land,and it is more conducive to the ecological management and restoration of sandy land.In this paper,six typical artificial vegetation(Pinus sylvestris var.Mongolica,Amorpha fruticosa,Medicago sativa,Hedysarum scoparium,Artemisia desertorum,Amygdalus pcdunculata Pall)and bare sand(CK)in the Mu Us sandy land were studied.The changes of soil moisture,nutrients,bulk density,particle composition and soil bacterial community structure in the 0-40 cm soil layer were studied by combining field sampling and indoor analysis.The relationship between vegetation restoration and soil physical,chemical properties and soil bacterial community structure was analyzed.The main research results are as follows:(1)The soil moisture in the sample plots with different vegetation restoration measures gradually increased with the increase of soil depth,and there was significant difference between different vegetation restoration measures and the control bare sand(p<0.05).The average water content of soil profile at 2m depth in different vegetation restoration sample plotswas lower than that in the control,and the lowest was Pinus sylvestris var.Mongolica sample plot,followed by Medicago sativa,which is 53.3% and43.2% less than the control,respectively.The soil water storage capacity of Hedysarum scoparium plot was the largest.Comprehensive analysis showed that the soil of Hedysarum scoparium have the highst soil moisture,and followed by Amygdalus pcdunculata Pall.(2)The content of soil organic carbon was still at a low level after different vegetation restoration,but it was significantly higher in the surface layer than the bottom layer(p<0.05).The average content of total nitrogen in the soil of Hedysarum scoparium plot was the highest,followed by Medicago sativa and Amygdalus pcdunculata Pall.The content of available nitrogen in different vegetation plots was significantly lower than thecontrol.The content of total phosphorus and total potassium in soil had no obvious change rule,but the content of available phosphorus in the soil of different vegetation was lower than the control.The soil nutrient index under different vegetation restoration showed that all the 6 restoration measures could improve the soil nutrient level.The soil nutrient index of Hedysarum scoparium was the highest which was 0.65.Artemisia desertorum has the lowest soil nutrient index,which was 0.35.(3)The coefficient of variation of soil bulk density in the Mu Us sandy land was all lower than 10%,which belonged to weak variation.The soil bulk density of Amygdalus pcdunculata Pall.was the lowest,followed by Hedysarum scoparium.The composition of soil particles in Mu Us Sandy Land was mainly sand particles,with the highest content of medium sand particles,followed by fine sand particles and finally coarse sand particles.(4)The diversity of bacterial community in different vegetation restoration soil(0-20cm)was lower than the control,and the Shannon,Simpson and Chao1 indexes in 6vegetation restoration samples were lower than the control.While in the 20-40 cm soil layer,The vegetation restoration significantly improved the diversity of bacterial community structure,and in the soil of Hedysarum scoparium was the highest(p<0.05).At the level of phylum,the dominant bacterial comunity in the soil of 0-40 cm was Actinobacteria,Proteobacteria and Acidobacteria.The relative abundance of soil bacterial community,especially Actinobacteria,was increased in the soil of 6 vegetations.Redundancy analysis(RDA)found that environmental factors had significant effects on soil bacterial community structure.Ammonium nitrogen,p H and total nitrogen had the greatest effect on bacterial community structure.Ammonium nitrogen as the most sensitive environmental factor was significantly correlated with Actinobacteria,Proteobacteria and Acidobacteria..Based on the above analysis,from the perspective of improving soil quality,the vegetation restoration process in Mu Us Sandy Land should be mainly based on Hedysarum scoparium and Amygdalus pcdunculata Pall.The above conclusions provide theoretical basis for vegetation restoration and ecological restoration in Mu Us Sandy Land.