3.1 Influence of wind speed and coverage on the wind erosion of biological soil crusts
In the natural environment, there are many factors that affect the growth and development of BSCs and their ecological contribution. In this control experiment, the largest influencing factors on the amount of wind erosion of BSCs are wind speed and coverage. From Figure 2, a clear influence of wind speed and coverage on the amount of wind erosion can be seen. The amount of wind erosion of algae crust and moss crust increases with increasing wind speed, and decreases with increasing coverage. Comparing the two BSCs, the change in the algae crusts is relatively stable, while the moss crusts have abrupt changes in wind erosion under coverage between 25% and 50% or wind speeds of about 12 m/s. The above phenomenon shows that the ability of different BSCs to consolidate soil and sand is significantly different.
Figure 2. The relationship between wind erosion, wind speed and coverage of BSCs. (The color from dark to light indicates the amount of wind erosion from small to large. The span of wind erosion produced by the different BSCs is different, which is reflected in the legend of this figure.)
Through the control of wind speed and coverage, the linear regression equations of wind speed, coverage and wind erosion under two kinds of BSC conditions were established respectively, and the importance of influencing factors was judged according to the standardized coefficients (Table 2). The linear regression fit of the two BSCs is good. Among the factors that affect the amount of wind erosion of algae crusts, the coverage (0.67) is stronger than wind speed (0.65), and among the factors that affect the amount of wind erosion of moss crusts, the coverage (0.53) is weaker than wind speed (0.58). The influence of the two factors is similar, which proves that in the process of windbreak and sand fixation, not only must the wind speed be reduced, but also the surface coverage must be ensured to reach the standard. The best effect of suppressing wind erosion can be achieved considering both factors.
Table 2. Regression equations of wind erosion of biological soil crust