Incorporating biological soil crusts into the B factor to enhance the accuracy of soil erosion models in drylands

Accurately predicting soil loss is crucial for the ecological environment
protection in drylands. Biological soil crust (biocrust), which is
widespread surface coverings in dryland ecosystems, can significantly
reduce soil loss on slopes. However, the existing soil erosion models
often inadequately account for the effect of biocrust, which may lead to
overestimation of soil loss in areas covered by biocrust. Accordingly, we
analyzed the relationship between the soil loss ratio (SLR) and biocrust
coverage through the soil loss data from 18 simulated rainfall
experiments. Subsequently, we incorporated the biocrust factor into the B
factor of the Chinese Soil Loss Equation (CSLE). In addition, we used the
soil loss data from six-year natural rainfall to investigate the
relationship between soil loss and biocrust coverage under natural
rainfall conditions and verified the revised CSLE model. The results
showed that soil loss decreased with the increase in biocrust coverage
under natural rainfall conditions, and the degree of decrement was related
to the effective rainfall. There was a significant negative exponential
function relationship between the SLR and biocrust coverage. Based on
this, the BBSC was developed as a sub-factor of the B factor in the CSLE,
with the formula BBSC = 0.8417e-0.0688C (R² = 0.880, P < 0.01).
Compared with the classic CSLE, the prediction accuracy of the revised
CSLE was significantly enhanced. This study verified the importance and
practicality of revising the erosion model so as to consider the effect of
biocrust on soil loss and provided valuable reference for the revision of
erosion models in drylands covered by biocrust, such as the Loess Plateau
in China.