Water Infiltration Characteristics and Model Simulation of Bryophytes on Surface Layer of Clay Soil Under Short-term Heavy Rainfall

Abstract

[Objective] The mechanism on how bryophytes influence water infiltration in the soil surface layer following a short period of heavy precipitation was studied in order to provide data support for the use of bryophytes to control soil erosion in rocky desert areas. [Methods] We measured soil water infiltration in a laboratory study using a one-dimensional soil column covered with Hypnum plumaeforme, Anomodon viticulosus, Weisia controversa, or Bryum coronatum after a short period of 20 mm of precipitation. We used the classical Horton infiltration model and Singh’s entropy infiltration equation to simulate water infiltration, and compared the differences in soil water infiltration. [Results] ① The initial, stable, and mean infiltration rates and the cumulative infiltration amount for the bryophyte-cover treatments were all greater than observed for the bare soil treatment (p<0.05). The four infiltration characteristic values were 0.718 cm/min, 0.279 cm/min, 0.180 cm/min, and 19.575 cm, respectively, for the Bryum coronatum treatment, which had the slowest infiltration rate, and the respective values were 7.65%, 8.56%, 11.90% and 3.75% greater than those observed for the bare soil treatment. The reason that the bryophyte-cover treatments increased water infiltration was that the bryophytes prevented the production of a physical crust on the soil surface. This effect was greater than the effect of the bryophyte layer to intercept and prevent water infiltration. ② The four bryophytes produced different effects to promote or impede water infiltration during the infiltration process, resulting in significant differences in water infiltration eigenvalues (p<0.05). Infiltration characteristics were negatively correlated with rhizoid density, rhizoid length, and saturated water absorption rate of bryophytes, and positively correlated with bryophyte roughness, but the correlation was small. ③ The classical Horton infiltration model was more suitable for simulating the soil water infiltration process of bryophyte-covered soil. The Philip model was more suitable for simulating bare soil water infiltration. If the accuracy requirement is not high and a simple model is desired, Singh’s entropy infiltration equation can be used as well as the E-Kostiakov infiltration model. [Conclusion] Bryophytes covering the soil surface layer increased water infiltration following a short period of intense precipitation of 20 mm, which was mainly due to the presence of bryophytes impeding the formation of physical crusting of the soil surface layer.

Keywords

• bryophytes
• short time heavy precipitation
• water infiltration
• infiltration model