Mosaic desert pavement influences water infiltration and vegetation
distribution on fluvial fan surfaces
Abstract
Desert pavements are critical for maintaining ecological stability and
promoting near-surface hydrological cycle in arid regions. However, few
studies have reported the desert pavements on ecological on fluvial
fans. Although desert pavement surfaces appear to be barren and flat, we
found that the surfaces were featured by mosaic pattern of desert
pavement (DP) and bare ground (BG). In this study, we investigated the
effects of mosaic DP on water infiltration and vegetation distribution
at six sites (i.e. one on the hillside and five in the sectors of
fluvial fans) along a southwest belt transect on the fluvial fans in the
Northern Linze County, in the middle of Hexi Corridor. The results
showed that significant differences of Mosaic DP between hillside and
sectors of fans were found in pavement thickness, thickness of vesicular
horizon (Av thickness), particle composition and bulk density, rather
than soil moisture content (SMC), gravel coverage and surface gravel
size. The mosaic DP can inhibit water infiltration by pavement layer,
where the sorptivity (S), initial infiltration rate
(iint) and steady- state infiltration rate
(isat) and infiltration time (T) averaged
1.30 cm/min-0.5, 5.03 cm/min, 0.23 cm/min, and 12.76 min respectively.
If pavement layer was scalped, the S, iint
and isat increased by 0.75 cm/min-0.5, 2.90
cm/min and 0.13 cm/min, respectively, and the T was shortened by
5.34 min. Water infiltration was mainly controlled by the pavement layer
thickness (+), Av thickness (-), surface gravel coverage (-), and fine
earth (+) and fine gravel (-) of pavement layer. Mosaic DP grew less
shrubs than mosaic BG where distributed plenty of herbs. It can be
concluded that desert pavements can keep vegetation stability by
self-regulating rainfall. This study would deepen our understanding of
the eco-hydrological cycle of pavement landscape in arid regions.