Comparative Study On Sand-fixation Effect Of Three Herbaceous Plants By Wind Tunnel Experiment

Desertification is a worldwide environmental problem,which seriously restricts the sustainable development of regional economy and society.Wind erosion desertification is one of the important types,and wind control and desertification control has become an important task in the economic and social development of arid and semi-arid regions.In desert ecosystem,especially desertification steppe ecosystem,although herbaceous plants have very small biomass,they give great contribution to species richness and diversity for plant community.Moreover,herbaceous plants have the advantages of rapid population reproduction and rapid growth,and have the unique function of maintaining habitat stability.Therefore,herbaceous plants also play an important role in wind prevention and sand fixation,and plant coverage and plant type are the main factors affecting their sand-fixation ability.It is important to identify the difference of sand-fixation effect of herbaceous plants with different plant types in ecological restoration measures,but there are few relevant researches at present.By wind tunnel simulation experiments in this paper,in the blank control（0%）and five kinds of coverage（25%,30%,35%,40%and 45%）,under the condition of three kinds of plants type（creeping,globular,plexiform）herbs wind speed,wind erosion rate and wind erosion of sand inhibition rate were determined,the contrast analysis of the situation about the plant type plant of wind erosion and wind erosion inhibition,mainly has the following findings:（1）The wind erosion rates of the three plant types showed a linear decreasing trend with the increase of coverage,and had a high correlation coefficient（R²>0.87）.From the slope of the fitting trend line,it was plexiform>creeping>globular.The wind erosion inhibition efficiency of the three plant types showed a linear increase trend with the increase of coverage.The smaller the coverage,the greater the difference among the three plants,and vice versa.The differences of sand-fixation ability of the three plants were closely related to their plant type,density of branches and leaves,and growth characteristics of plant height.（2）The wind erosion resistance of the three plant types varied with the coverage.The lower the coverage,the greater the difference of wind erosion rate among the three,and with the increase of coverage,the difference of wind erosion rate among the three gradually decreases.Under the same coverage,the wind erosion rate of plexiform is always higher than that of globular and creeping.When coverage is 35%,the wind erosion rate of globular and creeping is very close(0.73 g·m^-2·min^-1).When coverage is less than35%,the wind erosion rate of globular is smaller than that of creeping,and when coverage is greater than35%,the wind erosion rate of globular is larger than that of creeping.When the coverage is low,the wind erosion inhibition rate of different plant types varies greatly,and globular or creeping can achieve the sand fixation effect of plexiform under the condition of high coverage.The wind erosion inhibition efficiency of creeping and globular plants was 47.55%and 55.70%when coverage was 30%,which was close to the wind erosion inhibition efficiency of plexiform plants with coverage of 40%（48.46%）and 45%（56.94%）,respectively.（3）Globular and creeping plants belong to high sand-fixation capacity,while plexiform belong to low sand-fixation capacity.The wind erosion rate of three plant types is lowest in creeping,followed by globular,and highest in plexiform.The wind erosion inhibition rate is highest in creeping,followed by globular,and lowest in plexiform.From the perspective of sand fixation,creeping and globular plants are more suitable for biological sand fixation projects in areas with less external sand sources.In terms of sand burying resistance,plexiform and globular plants are more suitable for biological sand fixation projects in areas rich in exotic sand sources.