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High altitude wetlands on the Tibetan Plateau have been shrinking due to anthropogenic disturbances and global climate change. However, the few studies that have been conducted on wetlands are inconclusive about the effect of soil moisture on seed banks and potential of seed banks in wetlands with different levels of soil moisture for regeneration of dried wetlands. We investigated seed banks and plant communities along a soil moisture gradient. A structural equation model was used to analyze the direct and indirect effects of soil moisture on seed banks, as well as the relationship between plant communities and seed banks. Although soil moisture had no direct effects on seed bank richness and density and indirect effects on seed banks through plant community, it had indirect effects on the seed bank through soil pH. Soil moisture also did not have direct effects on plant community richness, but it had indirect effects through soil pH. Plant community composition changed with soil moisture, but aboveground plant abundance and seed banks composition did not change. Low similarity exists between plant community and seed banks for all wetlands, and similarity decreased along the moisture gradient. The key factor determining plant community diversity was soil pH, while seed bank diversity was mainly affected by soil pH and plant community diversity with wetland drying. Although potential for regenerating the plant community from the seed bank decreased with an increase in soil moisture, drained wetlands still have enough residual seeds for successful restoration of species-rich alpine meadows. [ABSTRACT FROM AUTHOR]

When restoring dryland ecosystems, growing biological soil crust (biocrust) may greatly change the redistribution of rainfall in layered soils. However, ecohydrological modelling studies generally ignore biocrust and thus, the ecohydrological effects of biocrust on restorations remain largely unexplored. Using a long-term restoration case (located in the southeast edge of the Tengger Desert, northern China), we developed an ecohydrological model with explicit consideration of the infiltration in three layered soils (biocrust, shallow and deep sand layers) to investigate influences of biocrust on restoration dynamics in drylands. The proportion of infiltration that reaches ‘annual grass’ (including biocrust and shallow sand layers, 0–30 cm) and ‘shrub’ layers (30–150 cm) with biocrust significantly increased and decreased relative to the values without biocrust, respectively. Meanwhile, biocrust significantly decreased soil water content in deep sand layer, but not in shallow sand layer. As more water was used by transpiration than evaporation, the ecosystem with biocrust reached a final grass-dominated state (high grass cover of 40%, low shrub cover of 4%) rather than a shrub-dominated state (grass cover of 3%, shrub cover of 20%). This study suggests that we need to account for the roles of biocrust on rainfall infiltration to better understand vegetation and restoration dynamics in dryland ecosystems. [ABSTRACT FROM AUTHOR]