Plot-based study to evaluate raindrop detachment capacity on moss-dominated biocrusted slope under simulated rainfall with different intensities

Abstract

Biocrusts play a critical role in prevention of erosion, but little is known on the relationship between biocrust cover and raindrop detachment capacity at the slope scale. Evaluating the raindrop detachment capacity on biocrusted slope is essential for better knowledge of the rainfall-induced erosion of biocrusted slope. Thus, laboratory simulated rainfall experiments were conducted on plots (140 × 120 cm) representing moss-dominated biocrusted slopes to measure the amounts of raindrop detachment under a complete combination of different biocrust cover (0%, 20%, 40%, 50%, 60%, and 80%) and rainfall intensities (42, 60, 90, 120, and 150 mm h−1) at 26.79% slope gradient with two replications. The results showed that the biocrust cover, rainfall intensity, and their interaction all significantly affected the raindrop detachment modulus (RDm). The RDm in biocrust plot was significantly lower than in bare soil plot under rain events with the same rainfall intensities. The lower biocrust cover or the larger rainfall intensities led to higher RDm. Reduction benefit of raindrop detachment modulus (RB-RDm) were greater than its corresponding biocrust cover values. When the biocrust cover increased from 20% to 40%, the increase range and growth trend of RDm decreased with increasing rainfall intensity. Our results indicated that the development of biocrusts on slope is an effective way of reducing raindrop detachment by protecting soil in their covered area and increasing flow depth. When moss-dominated biocrust cover reached 40%, the raindrop detachment capacity effectively weakened even under rain events with large rainfall intensities. These findings may conducive to offer a scientific guidance for soil erosion control in the Loess Plateau and in other arid and semiarid regions.