2.2 Biological soil crust sample collection
In this study, the undisturbed soil collection method was used to
collect algae and moss crust-covered soil. The size of the undisturbed
soil collection box used in the study was 50 cm×20 cm×15 cm. The four
sides of the collection box were inserted into the soil as a whole to
complete the fixation of the sample. The soil around the box was dug and
the collection box was taken out containing the undisturbed soil. The
box was closed at its bottom cover. The surface of the undisturbed soil
sample was covered with a non-sticky plastic film to prevent soil damage
and leakage. The soil sample assessed using a wind tunnel test. This
study uses the point sampling frame to measure the BSC coverage of the
soil (Li et al., 2010). Based on the 4 kinds of BSC coverage, in
combination with the subsequent wind tunnel test, this study needs to
repeat each measurement 3 times under 5 wind speed gradients. Therefore,
15 replicates of undisturbed soil samples for each coverage are ensured,
setting up a statistically defensible experimental design. The
classification of coverage is shown in Table 1.
Table 1. Coverage of biological
soil crust