Coupled effects of biocrusts and herbaceous plants on slope hydrology
and sediment yield
Abstract
Biological soil crust (BSC), as a groundcover, is widely intergrown with
grass. The combined effects of BSC and grass during rainfall on runoff
and sediment yield are still unclear. In this study, simulated rainfall
experiments were applied to a soil flume with four different slope cover
treatments, namely, bare (CK) and Stipa bungeana Train. (STBU),
BSC, and STBU + BSC to observe the processes of runoff and sediment
yield. Additionally, the soil moisture at different depths during
infiltration was observed. The results showed that the runoff generated
by rainfall for all treatments was in the following order:
BSC>STBU+BSC>CK>STBU. Compared
with CK, the STBU promoted infiltration, and BSC and STBU+BSC inhibited
infiltration. The BSCs obviously inhibited infiltration at a depth of 8
cm. As the soil depth increased to 16 cm and 24 cm, the effects of STBU
on promoting infiltration were stronger than those of BSC on inhibiting
infiltration. Compared with the CK, the flow velocity for the BSC, STBU
and STBU + BSC treatments was reduced by 62.79%, 32.27% and 68.29%,
respectively. The BSC and STBU increased the critical shear stress by
increasing the resistance. Additionally, the BSC, STBU and STBU+BSC
treatments reduced the sediment yield rate by 80.8%, 99.8% and 99.9%,
respectively. The soil erosion process was dominated by the soil
detachment capacity in the CK, BSC and STBU+BSC treatments, while the
STBU treatment showed a transport-limited process. This study provided a
scientific basis for the reasonable spatial allocation of vegetation in
arid and semiarid areas and provided a scientific basis for the
correction of vegetation cover factors in soil erosion prediction
models.