Natural revegetation during restoration of wetlands in the Sanjiang Plain, Northeastern China

As a key part of Chinese environmental policy, wetland restoration has been done for more than 10 years in the Sanjiang Plain, Northeastern China. Wetlands in this region revegetate by natural recolonization after rewetting. Understanding how restored wetland communities deviate from natural conditions can provide important insights into the mechanisms of recovery and improve restoration practice. The floristic composition of the vegetation of four restored wetlands were compared to the adjacent natural sedge meadows in the Sanjiang Plain. We found that Carex species, common dominants of natural sedge meadows, seldom naturally recolonized drained wetlands following hydrologic restoration. Other productive perennials, including Phragmites australis, Calamagrostis angustifolia and Typha angustifolia had dominated and expanded significantly on the restored wetlands. The mean aboveground biomass in the restored wetlands was much higher than the natural wetlands, while the mean species richness in the natural wetlands was much higher than the restored wetlands. Our results suggest that it may be relatively easy to restore high productivity in restored wetlands because of the dominance by productive species. However, Management, such as active revegetation of sedge meadow, particularly tussock-forming Carex, should be an important component of restoration practice to ensure that the restored wetlands support the region's biodiversity in the Sanjiang Plain.