基于风洞模拟的荒漠草原不同放牧强度抗蚀特征比较

Comparison on the Anti Erosion Characteristics Under Different Grazing Intensities on the Desert Steppe Based on the Wind Tunnel Simulation

以内蒙古高原荒漠草原亚带短花针茅草原为研究对象,在长期随机区组放牧试验地(对照样地CK、轻度放牧LG、中度放牧MG、重度放牧HG的放牧强度分别为0,0.93,1.82,2.71只羊/hm^2)取原状土样,并进行室内风洞吹蚀试验,研究荒漠草原放牧强度与风蚀速率的定量关系及估测不同放牧强度荒漠草原风蚀总量。结果表明:不同放牧强度处理区的群落结构特征差异显著(p<0.05),但土壤结皮和0—5cm深度土壤粒径组成仅粘粒含量差异显著,其他粒径组成无显著差异(p>0.05);不同放牧强度处理区风速风蚀速率方程有较好的指数拟合,HG和MG区的方程拟合系数R^2大于LG和CK区,且表征风速敏感性的参数B随着放牧强度的增加,从CK的0.15增加到HG区的0.21,表明在放牧条件下,风蚀速率对风速增加更加敏感;风蚀率与风速和放牧强度具有极显著的正相关关系(r=0.601和r=0.563,p<0.01),与盖度和高度具有极显著的负相关关系(r=-0.544和r=-0.535,p<0.05);基于试验区2年的小气象站数据和土壤风蚀方程,短花针茅草原年均风蚀量在110~680t/(km^2·a)之间,随着放牧强度的增大,单位面积年均风蚀量逐渐增加,CK处理区年均风蚀量为115.24t/(km^2·a),大约为HG区风蚀量648.95t/(km^2·a)的17%,MG区和LG区分别是重度放牧区的60%和23%。

Take the long-term grazing site on Stipa breviflora desert steppe in Inner Mongolia plateau as the research object, randomized blocks were adopted with 0.93 （LG）, 1.82 （MG）, 2.71 （HG）, 0 （CK） sheep/ hm^2 and the wind tunnel test of undisturbed soil samples were carried out in order to study the quantitative relationship between grazing intensity and wind erosion rate, and to estimate the total amount of wind erosion under different grazing intensities on the desert steppe. The results indicated that the community structure characteristics of different grazing intensities were significantly different （p〈0.05）, but the soil crust and change of soil particle size composition in 0-5 cm depth were not significant （p〉0.05）. The equation of wind velocity and wind erosion rate in different grazing intensity areas had a better fit index, however, the equation fitting coefficients R2 of HG and MG were larger than that of LG and CK, and the parameter B for characterizing wind speed sensitivity increased from 0.15 in CK to 0.21 in HG with the increase of grazing intensities, it showed that the wind erosion rate was more sensitive to the increase of wind speed under grazing condition. Wind erosion rate had a very significant positive correlation with wind speed and grazing intensity（r=0. 601 and r= 0. 563, p%0.01）, and highly significant negative correlation with coverage and height（r=-0. 544 and r=-0. 535, p〈0.05）. Based on the two years＇ data of small meteorological stationand the equation of soil wind erosion, the annual wind erosion amount was between 110-680 t/（km^2·a） on Stipa breviflora desert steppe, the annual average amount of wind erosion per unit area increased gradually with the increase of grazing intensity, the average annual wind erosion amount was 115.24 t/（km^2·a） in CK area, it was about 17% of HG area wind erosion amount that was 648.95 t/（km^2·a）, MG area and LG area were 60% and 23% of HG area, respectively.