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Abstract: The Chinese Loess Plateau (CLP) is a unique Critical Zone with deep loess deposits, where soil moisture is primarily replenished by seasonal monsoon rainfall. However, the role of vegetation, coupled with complex topography, on rainwater infiltration on the CLP, especially after long‐term revegetation for controlling erosion, is inadequately quantified. Over the growing season of 2016, we monitored soil moisture at the 30‐min interval at 5 depths (10, 20, 40, 60, and 100 cm) in an afforested catchment and a nearby catchment with natural regrowth of grasses. Two monitoring sites were established in each catchment, one in the downhill gully and the other in the uphill slope. We found that vegetation, topography, and rainfall attributes together determined rainwater infiltration and soil moisture replenishment. An accumulated rainfall amount of 9 mm was required to trigger soil moisture response at 10‐cm depth at the 2 grassland sites and the forestland uphill‐slope site whereas 14 mm of rainfall was required for the forestland gully site covered by dense undergrowth and trees. Rainfall events with larger sums and higher peak intensities permitted rainwater infiltration to deeper soil depths. However, no rain recharged soil moisture to 100‐cm depth during the monitoring period. The forestland uphill‐slope site showed the deepest wetting depth (up to 60‐cm depth), fastest wetting‐front velocity (up to 4 cm/hr below 10‐cm depth), and the most significant soil moisture increase (up to 15% cm 3 cm−3 increase at 10‐cm depth) after rainfall in the growing season. The grassland gully site had the highest soil water storage, whereas soil moisture was depleted the most at the forestland gully site. Findings of this study reveal the transient dynamics of soil moisture after rainfall on the CLP, which signifies the role of revegetation on rainwater infiltration in the loess Critical Zone. [ABSTRACT FROM AUTHOR]

Land-use/vegetation is an essential variable on controlling the heterogeneities and distribution pattern of soil water content (SWC). Along with large-scale re-vegetation in arid and semi-arid areas, the variations of SWC ascribed to the land-use conversion have been considered as an important factor to assess the re-vegetation efforts. In this study, soil water data at the depth of 0–300 cm were obtained by field observation in two eco-hydrologic zones in Loess Plateau of China. The mean annual precipitation was 350–400 mm (zone-A) and 500–550 mm (zone-B), respectively. The differences in SWC were analyzed among different land-use types; and the SWC in different restoration years was also discussed using the method of space replacing time. Results indicated that (1) the differences in SWC between the two zones were lower in re-vegetated lands (2.76%, forestland and 4.22%, for shrub land) than in abandoned farmland (5.85%). The differences in re-vegetated lands diminished gradually as the soil depth (0–300 cm) increased, whereas the abandoned farmland represented an opposite trend. (2) Although the variation trends of SWC in abandoned farmland of the two zones were different as the restoration years increased, the differences in SWC between abandoned farmland and native grassland both diminished gradually. This meant the soil water deficit relative to native grassland would be alleviated as the progress of abandoned farmland. (3) As the restoration years increased, the differences in SWC between re-vegetated lands and native grassland increased gradually because of the continuous decrease of SWC in re-vegetated lands. The consequence will be that the soil water deficit in the re-vegetation lands is aggravated continually. From the perspective of soil water restoration and conservation in semi-arid areas, the abandoned farmland should be a more reasonable method than re-vegetated lands covered with introduced plants. [ABSTRACT FROM AUTHOR]

Abstract: Biological soil crusts are receiving increasing attention due to their potentially positive effects on desert ecosystems. Artificial propagation of crusts is one way to restore degraded desert soils. However, little is known about their effectiveness on overland flow or water infiltration. Consequently, a study was done on soils of the Loess Plateau of China that had crusts propagated on different slopes. The results show that: (1) it is feasible to artificially grow moss-dominated biological soil crusts (moss crusts) in laboratory; when inoculated by sprinkling crushed fragments of stems and leaves of natural moss crusts they will cover the soil surface almost completely after about 10 months; (2) the artificially propagated moss crusts significantly increase infiltration consequently decreasing overland flow and this increase in infiltration is positively correlated to the soil coverage extent; (3) overland flow results increased by slope in moss-protected and bare soils, consequently the action of moss crusts is particularly important for protecting steep slopes; (4) the start time of runoff process is delayed by moss crusts, and the soil water redistribution process is also greatly affected. These results may be useful for helping to control desertification on the Loess Plateau of China or similar regions. [Copyright &y& Elsevier]