Short communicationNatural succession is a feasible approach for cultivated peatland restoration in Northeast China

Peatland restoration has been attracting increasing attention and implementation since large areas of peatlands in China have been degraded or reclaimed to cropland in recent decades. However, the length of time for cultivated peatland to be restored to natural climax level in terms of vegetation remained unknown. A field experiment was conducted to investigate the characteristics of hydrology, plant community, and soil in abandoned 0-, 2-, 15-, and 30-year-old paddy lands and a natural peatland. The results showed a long-term rise in water level after restoration. Similarity indexes between restored sites and natural peatland also increased with the extension of restoration time. During the first three years after abandonment, weeds grew vigorously and almost overtook the entire experimental site. However, the plant community was dominated by a Carex schmidtii-Phragmites australis-Thelypteris palustris community, where similarity increased to 64% and vegetation succession approached a natural climax community after 15 years of restoration. Compared with the paddy field, total nitrogen (TN), total phosphorus (TP), total organic matter (TOM) in the soil at 0-30 cm depth and soil bulk density at 0-60 cm showed no significant change after 2 years of restoration. In the 15-year restoration site, however, TN and TOM at 0-30 cm increased by 108% and 86%, respectively (P < 0.01), and soil bulk density at 0-60 cm decreased by 40% compared with the paddy field (P < 0.05), and the values were already similar to the 30-year site and the natural peatland. Those findings indicate that the cultivated peatland could be restored effectively through natural succession.