4.1 Effects of coverage and wind speed on wind erosion and
particulate matter emission of biological soil crusts
There are many factors affecting wind erosion and particulate matter
emissions in the natural environment. Although the use of BSCs to cover
the ground has a significant effect, being human damage the largest
influencing factor (Neff et al., 2008). In this study, the areas covered
by BSCs belong to areas with low population density, so wind speed and
coverage have become the biggest factors affecting the wind erosion of
BSCs and particulate matter emissions (Hong et al., 2020). Comparing and
analyzing the factors influencing wind speed and coverage in Table 1 and
Table 2, the influence of wind speed and coverage on the amount of wind
erosion is similar, but the degree of influence on particulate matter
emissions is quite different. Specifically, the influence of coverage is
stronger than wind speed, and as the particle size decreases, the
greater the influence of coverage and smaller the influence of wind
speed, as shown in Figure 7. This phenomenon indicates that for BSCs,
coverage is more important than wind speed, which is closely related to
the nature of BSCs. Zou et al. (2018) summarized previous studies
indicating that particles with a size of 0.05 mm to -0.5 mm are most
likely to be eroded. The BSC can aggregate small particles in this size
range to form more stable large soil particles through the cementation
and adhesion of fungal hyphae (Eldridge and Greene, 1994). Xie et al.
(2007) also believed that the biomass of BSCs is closely related to its
erosion resistance. In addition, Spagnuolo et al. (2013) argue that the
surface of moss has a strong ability to adsorb particles, and some of
the particles with very small diameters can even interact with moss
cells. Thus, moss can become an environmental indicator. Microbes in
algae crusts have similar functions (Bailey et al., 1973). The previous
studies can prove that the structure and properties of BSCs are more
likely to affect the process of wind erosion and particulate matter
emission. Therefore, under the assumption of less human interference,
the surface particulate matter emissions of BSCs are more sensitive to
coverage, followed by wind speed.
Figure7. Influence of wind speed and coverage in particulate matter
emission