Effects of hydrologic mediation and plantation of Carex schmidtii Meinsh on peatland restoration in China's Changbai Mountain region

Abstract

Since large areas of peatlands in China have been degraded or reclaimed to cropland in recent decades, the conversion of these croplands to wetlands and the restoration of degraded peatlands by means of engineering have been attracting increasing attention. Hydrologic mediation and plantation of dominant peatland species were implemented to determine the effects of these two artificial measures on revegetation and soil property improvement in paddy fields in the Changbai Mountains in Northeast China. The results showed that after a three-year restoration, compared to natural restoration treatment, planting of Carex schmidtii significantly reduced aboveground biomass by 45% (P<0.05), increased root biomass by 53% (P<0.05), increased the Shannon–Wiener Index by 17%, enhanced concentrations of total soil organic matter by 28% (P<0.05), reduced topsoil bulk density by 40% (P<0.05), and improved water retention capacity of the topsoil. These results demonstrate the ability of C. schmidtii to inhibit the growth of weeds and other nontarget species through competition, and to increase the amount of residual roots in soil due to its well-developed rhizomes. Aboveground biomass and total organic matter in hydrologic mediation were 38% lower and 37% higher than in the natural restoration treatment, respectively. However, annual precipitation in this area is 704.2mm, higher than most other area in Northeast China, and the Shannon–Wiener Index and soil bulk density were 4% and 29% lower than in the natural restoration treatment, respectively. Furthermore, the combined application of these two measures resulted in 35% lower aboveground biomass, 22% higher Shannon–Wiener Index, 16% higher topsoil organic matter, and 27% lower bulk density than in the natural restoration treatment. However, the growth of C. schmidtii was inhibited due to the reduction in its survival rate and basal width growth rate. Our results suggest that planting C. schmidtii is an effective way to promote the restoration of degraded peatland and enhance its carbon sink function in the Changbai Mountains. On the other hand, implementation of hydrologic mediation is not recommended for this rain-rich region.