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.

Desert pavements are the common features widespread in arid region, which are important for regulating the ecological and hydrologic processes. However, few studies focused on the role of water movement in maintaining ecologic function in desert pavement landscapes. This study determined the role of desert pavements in water infiltration on fluvial fans, which were reflected by characteristics of desert pavements and infiltration parameters in the middle reaches of Hexi Corridor. Six sites (i.e. one site in hill slope and other five sites in the piedmont) were selected for surveying soil properties within a 50-cm depth soil profile and measuring sorptivity (S), initial water infiltration (ii), steady-state infiltration rate (is) and infiltration time (T) in crust and scalped crust conditions under 5-cm pressure head. The results indicated that desert pavement surfaces were covered by a thin layer of protective crusts, which were primarily composed of fine earth (56.94%) and fine-medium gravel (40.46%). Although characterized by a big range of gravel coverage (19.48%- 97.63%), the crusts had small gravels (mean size: 0.58 cm) and extremely low soil moisture content (SMC; less than 1.30%), which two parameters did not significantly differ from each site in fluvial fans. The crusts were effective in restricting water infiltration capacity. When the crusts were scalped, the S, ii and is would improve 1.6, 1.7 and 1.6-fold, respectively. These three parameters significantly increased with gravel coverage and medium gravels, but significantly decreased with crust thickness and fine gravels. Desert pavements were closely with water regulation in arid systems, reflecting the vegetation distribution. This study highlights that desert pavements have a strong impact on water infiltration to function as regulating water resource and supplying water for vegetation growth.