Flow hydraulic responses to near-soil surface components on vegetated steep red soil colluvial deposits

•Flow velocities were reduced by the shallow fine roots of M. minutifora.•The main influencing factors of friction coefficients depended on plant types.•Increased fine root volumes increased both shear stress and stream power.•The effects of biocrusts alone were negative under high rain intensities.•Most positive effects weakened with increasing rain intensities.