The occurrence of biocrusts and its disturbance alters infiltration in
the Mu Us Desert. Knowledge of the hydrological properties of biocrusts
and estimation of soil hydraulic parameters are crucial to improve
simulation of infiltration and soil water dynamics in
vegetation-soil-water models. Infiltration experiment was conducted to
evaluate the effects of biocrust development and its disturbance on soil
infiltrability in Mu Us Desert, northwest of China. A combined Wooding
inverse approach was used for the estimation of soil hydraulic
parameters. The results showed that both lichen- and moss-covered
biocrusts had a negative influence on infiltration in comparison with
the bare soil. Moreover, moss-covered biocrusts had much lower soil
infiltrability compared to the lichen-covered biocrusts. Biocrust
disturbance alters infiltration, but its effect differs depending on the
biocrust and disturbance types. For high pressure heads, water retention
on the moss-covered soils was higher than on the lichen-covered soils.
Moreover, trampling caused a higher water retention at high pressure
heads. However, opposite was observed at low pressure heads. In
addition, moss-covered soils had lower hydraulic conductivity than the
lichen-covered soils. Additionally, for each biocrust-covered soil, both
trampling and scraping resulted in a higher hydraulic conductivity when
compared with the undisturbed soils. The occurrence of biocrusts and its
disturbance influenced van Genuchten parameters, and subsequently
affected the water retention curve, and thus altered the plant-available
water. The findings about the parameterization of soil hydraulic
properties have important implications for the simulation of
eco-hydrological processes in arid and semiarid ecosystems.