Seasonal variations in infiltrability of moss‐dominated biocrusts on aeolian sand and loess soil in the Chinese Loess Plateau

Abstract

Biocrust effects on soil infiltration have attracted increasing attention in dryland ecosystems, but their seasonal variations in infiltrability have not yet been well understood. On the Chinese Loess Plateau, soil infiltrability indicated by saturated hydraulic conductivity (K s ) of biocrusts and bare soil, both on aeolian sand and loess soil, was determined by disc infiltrometer in late spring (SPR), midsummer (SUM), and early fall (FAL). Then their correlations with soil biological and physiochemical properties and water repellency index (RI) were analysed. The results showed that the biocrusts significantly decreased K s both on sand during SPR, SUM, and FAL (by 43%, 66%, and 35%, respectively; P < .05) and on loess (by 42%, 92%, and 10%, respectively; P <.05). As compared with the bare soil, the decreased K s in the biocrusted surfaces was mostly attributed to the microorganism biomass and also to the increasing content of fine particles and organic matter. Most importantly, both the biocrusts and bare soil exhibited significant ( F ≥ 11.89, P ≤ .003) seasonal variations in K s , but their patterns were quite different. Specifically, the K s of bare soil gradually decreased from SPR to SUM (32% and 42% for sand and loess, respectively) and FAL (29% and 39%); the K s of biocrusts also decreased from SPR to SUM (59% and 92%) but then increased in FAL (36% and 588%). Whereas the seasonal variations in K s of the biocrusts were closely correlated with the seasonal variations in RI, the RI values were not high enough to point at hydrophobicity. Instead of that, the seasonal variations of K s were principally explained by the changes in the crust biomass and possibly by the microbial exopolysaccharides. We conclude that the biocrusts significantly decreased soil infiltrability and exhibited a different seasonal variation pattern, which should be carefully considered in future analyses of hydropedological processes.

500 million years of charted territory: functional ecological traits in bryophytes

“…In tropical montane environments, fog interception by bryophytes can significantly increase water inputs and storage (Chang et al 2002, Villegas et al 2008. bryophytes in soil crusts affect infiltration and runoff (Xiao et al 2019, Eldridge et al 2020. Global modelling suggests a considerable hydrological influence of bryophytes (and lichens) on rainfall interception (Porada et al 2018), and soil hydraulic conductivity (Voortman et al 2014) but also highlights the absence of empirical data for much of the globe.…”

Biocrust Research in China: Recent Progress and Application in Land Degradation Control

“…Biocrusts significantly alter the spatiotemporal redistributions of rainfall infiltration and soil moisture as well as reduce the effective supplementation of rainfall to deep soil ( Li et al, 2001 ; Bu et al, 2015a ; Wang et al, 2017 ; Xiao et al, 2019 ). The Gurbantunggut Desert receives precipitation ranging from 70 to150 mm; further, moss-, lichen-, and algae-dominated crusts have been shown to reduce the infiltration rate by 16.50–36.10, 33.98–46.42, and 35.92–50.39%, respectively, while reducing the 1-h accumulated infiltration rate by 16.10, 28.56, and 26.56%, respectively ( Zhang et al, 2006 ).…”

The role of biocrust-induced exopolymeric matrix in runoff generation in arid and semiarid zones – a mini review

“…Similarly, 1 mm-thick biocrusts which covered the xeric aspects of the dunes commonly generate runoff (Kidron, 1999;Kidron et al, 2003). With typical soils, some of which are well aggregated, having infiltration rates of 10-150 mm/h (Dunkerley, 2000;Kato et al, 2009;Wood and Blackburn, 1981), i.e., substantially lower than sand (having >300 mm/h of infiltration; Lichner et al, 2010;Xiao et al, 2019b), one may safely conclude that runoff over the 0.5 mmthick biocrusts was not impacted by the underlying sand, but rather by the biocrust. With HOF being the prevailing mechanism that determines runoff generation in arid and semiarid regions, the aggregation capability of the subsurface is of minor relevance.…”