Intact biological soil crusts greatly protect inclined surface from wind erosion in drylands

The scarcity of studies examining wind erosion modulus (WEM) under interactive environmental factors—particularly slope gradient (SG) and the biological soil crust (BSC) integrity—impedes the accurate assessment of BSCs’ protective role against wind erosion in drylands. As key natural stabilizers in these regions, BSCs mitigate wind erosion effectively by binding soil particles and enhancing surface roughness. In contrast, wind speed (WS) and disturbance level (DL) exert opposing effects, yet empirical evidence concerning the combined influences of SG and these integrated environmental factors on WEM remains scarce. To address this gap, we conducted wind tunnel experiments to quantify the effects of BSCs, SG, DL, and WS on WEM in the Tengger Desert, Northwest China. Our results showed that WEM decreased markedly with the presence and development of BSCs: specifically, intact and well-developed BSCs reduced WEM to nearly 0 g m−2 min−1, regardless of SG and WS. In contrast, WEM increased significantly with greater SG, DL, and WS, exhibiting a synergistic amplifying effect—relationships mediated by surface soil physical properties (SSPPs). Overall, BSCs—particularly through enhancing soil stability—markedly strengthen resistance to wind erosion, whereas disturbing factors (SG, DL, WS) degrade SSPPs and promote erosion. This study provides the first integrated assessment of BSCs–SG–DL–WS interactions in arid environments, highlighting intact BSCs as vital defensive barriers against wind erosion. The findings offer a mechanistic framework for dryland restoration strategies and improve predictions of dust emission dynamics under ongoing climate change.