Abstract: Surface wetness of Yuanchi peatland in the Changbai Mountains were reconstructed by comprehensive analysis on plant residue, testate amoeba and humification, using the age-depth model established with AMS ¹⁴C and ¹³⁷Cs dating methods. The response of surface wetness to climate change was addressed. Results showed that plant residues in the top 50 cm of peat sequence were dominated by mosses. Detrended correspondence analysis (DCA) of plant residue revealed that axis 1 of DCA biplot might represent mire surface wetness (MSW). MSW from 1962 to 2008 as indicated by axis 1 scores of DCA on plant residue were compared with depths to water table derived by testate amoebae-DWT transfer function and humification measurements, and the results showed that the trends of MSW reconstructed by three proxies were largely consistent. They were wetter MSW from 40-50 cm (1962 to 1975), 27-40 cm (fluctuating from wet to dry from 1975 to 1987), and 0-27 cm (drier from 1987 to 2008). Compared with instrumental data from nearby Erdao weather station, the reconstructed MSW was basically consistent with temperature change in this period. The decreases of MSW occurred when mean summer temperature and mean annual temperature were higher than long-term mean value. Our results suggest that the variability in MSW in the recent 46 years predominantly responded weakening of effective precipitation induced by increasing temperature.

Key words: plant residue, testate amoebae, humification, hydrological climate, Changbai Mountains