Study On Wind And Sand Prevention Effect Of Desert Shrub Community Based On Vegetation Silhouette

In this study,we revealed the effects of wind prevention and sand resistance of different vegetation types in desert ecosystems by studying the influence of typical plant plots in desert ecosystems on near-surface aeolian activities.Artemisia ordosica,Sarcozygium xanthoxylon,Haloxylon ammodendron and Tetraena mongolica were selected in the desert-oasis transition zone in the northeast margin of Ulanbuh Desert.The bare dune was used as a control sample（CK）to observe the aeolian activities of the community in different seasons and under the conditions of wind speeds.The research results show that:（1）The wind speed profiles in the plant community plot and the control plot are in line with the logarithmic distribution law U=a+bln Z（R²>0.90）,and the surface roughness has a significant increase compared with the moving sand dunes.The windproof effect shows a decreasing trend with the increase of the height above the ground.The windbreak effect of the plant community is large in the range of vegetation height,and also has a certain influence outside the range of plant height.Vegetation height,cover,and side cover can quantitatively express vegetation configuration,and have a linear relationship with the windbreak effect of E=a₀+a₁H+a₂C+a₃Ap（a₂>a₃>a₁）.Within the range of 0-200 cm above the ground height,the windproof effect is Haloxylon ammodendron>Sarcozygium xanthoxylon>Artemisia ordosica>Tetraena mongolica.（2）Under different wind speed conditions,the sediment transport rate showed a decreasing trend with the index Q=a+eb H,and the seasonal sediment transport rate was Autumn<Summer<Winter<Spring.The mean jump heights of sand grains in the plant community were higher than those in the control plots,and the sediment transport of 0-10cm was significantly lower than that of the moving sand dunes near the surface.The plant configuration and the sand blocking effect are in line with the linear relationship of E solid=a₀+a₁H+a₂C+a₃Ap.Under the average height of vegetation community,the sediment inhibition effect was above 90%（8.05 m/s,except for 54.2%of Artemisia oleifera community）,and the sediment resistance effects of the four plant communities were as follows:Haloxylon ammodendron>Sarcozygium xanthoxylon>Tetraena mongolica>Artemisia ordosica.（3）The influence of soil moisture content on sediment transport in the plant community is smaller than that of vegetation configuration,and the difference of seasonal sediment transport is affected by the frequency of seasonal sand-blowing winds and the average wind speed of sand-blowing winds.（4）In the analysis of the particle size of sand substances in different community sand collection instruments,the particle size content distribution curves of sand substances showed obvious unipolar distribution characteristics,and the average particle size showed a power index distribution with height.The effects of the four community plots on the three transport forms were slightly different,and the suspension matter was basically maintained at 40.40%-57.93%,the jumping mass was 40.41%-58.49%,and the creeping matter was 0.27%-1.41%.