Mosaic desert pavement influences water infiltration and vegetation distribution on fluvial fan surfaces

Abstract

AbstractDesert pavements (DPs) are critical for maintaining ecological stability and promoting near‐surface hydrological cycling in arid regions. However, few studies have focused on eco‐hydrological processes of DPs in the ecological systems of fluvial fans. Although DP surfaces appear to be barren and flat, we found that the surfaces are characterized by surface mosaic patterns of desert pavement (mosaic DP) and bare ground (mosaic BG). We investigated the effects of mosaic DP on water infiltration and vegetation distribution at six sites in fluvial fans (one on a hillside and five within the sectors of fans) along a southwest belt transect in northern Linze County, in the central Hexi Corridor (China). We found significant differences in mosaic DP between the hillside and sector sites in terms of pavement thickness and vesicular horizon thickness (Av thickness), particle composition, and bulk density, although significant differences were absent for mass soil water content, gravel coverage, and surface gravel size. The mosaic DP inhibited water infiltration by the pavement layer, where the sorptivity (S), initial infiltration rate (iint), steady‐state infiltration rate (isat) and infiltration time (T) averaged 1.19 cm/min‐0.5, 0.64 cm/min, 0.13 cm/min and 12.76 min, respectively. Where the pavement layer was scalped, the S, iint, and isat increased by 0.27 cm/min‐0.5, 0.52 cm/min, and 0.40 cm/min, respectively, and the T reduced by 7.42 min. Water infiltration was mainly controlled by the pavement layer thickness (+), Av thickness (−), surface gravel coverage (−), fine earth (+) and fine gravel (−) in the pavement layer. The DP surfaces only had a sparse covering of shrubs, but an abundance of herbs. Few shrubs were present on the mosaic DP, but a greater number of shrubs and herbs grew on the mosaic BG. It can be concluded that DPs can maintain vegetation stability for different surface mosaic patterns. This study deepens our understanding of the eco‐hydrological cycle of DP landscapes in arid regions.