Regulatory effect of biological soil crust distribution patterns on the spatial distribution of wind erosion on...

Biological soil crusts (biocrusts) are key factors influencing soil wind erosion in arid and semi-arid regions. However, the effects of their spatial distribution on the spatial differentiation of surface erosion remain unclear, hindering the understanding of the mechanisms of resistance to wind erosion and the precision prevention and control of wind erosion. We investigated the effects of biocrust distribution patterns (checkerboard, strip, and random) on the spatial distribution of wind erosion through wind tunnel experiments combined with structure from motion (SfM). The results showed that: 1) Compared with bare soil, both wind erosion rates and sediment transport rates decreased on biocrust slopes with random, strip, and checkerboard distribution patterns. Wind erosion rates were significantly reduced by 85.6%, 60.4%, and 57.3%, respectively, while the near-surface (0-6 cm) sediment transport rates decreased by 84.0%, 45.3%, and 34.8%, respectively. 2) The spatial distribution of slope erosion varied significantly across the biocrust distribution patterns. On the random-pattern slope, soil erosion areas were fragmented, mainly distributed around the slope periphery and in narrow pathways separated by biocrust patches. The relatively low erosion intensity and erosion depth mainly ranged from 0 to 2 mm. On the strip-pattern slope, soil erosion and deposition areas were alternately distributed, with erosion continuously occurring within bare-soil patches and erosion depth mostly ranging from 0 to 4 mm. On the checkerboard-pattern slope, erosion was most severe in the upwind region, weaker and discontinuous in the mid-slope region, and mostly distributed at the edges of bare-soil patches, with erosion depth concentrating between 0 and 4 mm. 3) Compared with the bare-soil slope, the average erosion depth on biocrust-covered slopes decreased by 2-4 mm. The proportion of erosion area and erosion volume decreased by 23.4%-39.8% and 54.6%-74.0%, respectively. The deposition area and deposition volume increased by 7.2-10.0 and 8.3-15.4 times, respectively. 4) The deposition capacities of slopes with different biocrust distribution patterns were similar. The random-pattern slope showed weak erosion and the strongest resistance to wind erosion, whereas both the strip- and checkerboard-pattern slopes showed relatively strong erosion and weaker resistance to wind erosion. The distribution pattern of biocrusts could influence the connectivity among bare-soil patches and change the locations where wind erosion occurs and the sediment transport pathways, with consequence on wind erosion intensity.