Research On The Red Line Of Utilization In Hulun Buir Grassland Based On The Function Of Windbreak And Sand Fixing

This paper mainly focused on the wind and sand fixing function of the Ewenki grassland,Hulun Buir,China.The influence of wind speed,vegetation coverage and slope on wind erosion was measured,and the influence of different wind speed,different vegetation coverage and different slope on the aeolian movement rules and characteristics of wind erosion of grassland was determined with quantitative indicators.On the basis of maintaining the ecological function of wind and sand fixation,the limit value calculation technology of regional economic utilization was established.The main results were as follows:1.The influence of wind speed on the surface wind profile of different underlying surfaces decreased with the vegetation coverage decrease.Under the same slope,the weakening effect of the wind was reduced with the decrease of vegetation coverage.The wind speed increases sharply and then changes slowly with the increase of vegetation height,when the wind speed was 0 degree and the vegetation coverage of the meadow grassland,typical steppe,fixed sandy land and semi fixed sandy land was 40%,30%,20%and 10%,separately.2.As the wind speed increases,the aerodynamic roughness of meadow grassland varied in different forms,but the decreased trend was obvious overall.The aerodynamic roughness of typical steppe changed in different forms,and had a rising trend.The aerodynamic roughness of fixed sandy land showed a clear decreasing trend and the aerodynamic roughness appeared in semi fixed sandy land changes in different forms and showd a downward trend after the wind speed was greater than 13 m/s.3.Under different wind speeds,the sand transport rate of meadow steppe,typical grassland,fixed sand land and the semi fixed sand land were tend to be the same trend.The 4 types are scattered in the height range,mainly concentrated in the middle and low section of the sand sampler.The sand transport rate in the range of 0?2cm is generally less than that in the range of each height section.The maximum sand transport rate in the 3?4cm section and the increase of the sand transport rate upward with the height increase rapidly,that is,the higher the hight from the ground,the less the sand transport rate was.Under the same wind speed,the sediment transport volume gradually decreases with the increase of vegetation coverage,and the sediment transport over 80%of the underlying surface is concentrated in the height below 10cm,and the amount of sediment transport increases with the increase of wind speed under the same wind speed under the same wind speed.4.Through the analysis of different wind erosion factors,the wind speed,vegetation coverage and slope have a significant influence on wind erosion.When the wind speed is at the fixed value of vegetation cover and slope,the value of grassland wind erosion increases with the increase of wind speed;the vegetation coverage takes the wind speed and slope to determine the value of the grassland wind.The value of erosion was increased first and then decreased with the increase of vegetation coverage.When the slope was fixed on vegetation coverage and wind speed,the value of wind erosion in meadow grassland,typical steppe and fixed sand land increased first and then decreased with the change of slope from-30 degrees to 30 degrees.5.The constructed wind erosion model was processed by ArcGIS superposition,and the corresponding wind erosion equation was used.When the wind erosion amount was minimum(Y=0),the wind speed(X2)with 13.6m/s,the slope degree(X3)was in 0 level,the corresponding vegetation coverage value was obtained.The corresponding coverage of this region was varied in the range of 30%-35%.That was the baseline coverage of the baselines of windbreak and sand fixation.The grassland which is larger than this coverage can not only maintain the ecological function of windbreak and sand fixation,but also can be used for economic utilization.6.The baseline vegetation biomass in 2013 was higher than that in 2010 in the same type of grassland.In 2010,the biomass of meadow grassland was the highest,followed by typical steppe,semi fixed sand land and fixed sand land,while in 2013,the order of biomass was meadow grassland,typical steppe,fixed sand land and semi fixed sand land.From the area of land type,some semi fixed sandy land between 2010 and 2014 was changed to fixed sand,and there was a slight change in area between different types,which leads to the change of biomass.7.The limited utilization of regional economic value shows that:lower than the baseline coverage area of Ewenki sand fixing region was 141906.3ha in 2010,93593.75ha in 2013,this part was the forbidden grazing area,which accounts for the whole area with the ratio of 7.86%and 5.17%.The area which meets the baseline coverage,and the carrying capacity of less than 1.8935 sheep unit can be grazed moderately,the corresponding area was 522431.30 ha in 2010 and 651768.80 ha in 2013,which accounted for the whole area with the ratio of 28.92%and 36.03%.The carrying capacity of more than 1.8935 sheep unit region was economic utilization area,the corresponding area was 1142200 ha in 2010 and 1063400 ha in 2013,which accounted for the whole area with the ratio of 63.23%and 58.79%.