Holocene peat humification and carbon dynamics in the Westerlies-influenced Northwest China

Abstract

Understanding peat carbon dynamics in the past is of significance, given the uncertainties as to whether there will be an increase or a reduction in carbon as a result of future climate change. Studies of peat carbon dynamics have primarily been conducted in monsoon-influenced China. However, data relating to carbon dynamics in peat deposits has not yet been investigated in Westerlies-influenced Northwest China (NWC). In this study, the Holocene carbon accumulation rate (CAR) is explored at the Tuolehaite peat core, with a mean rate of growth of 2.4 yr mm-1, 0.4 mm yr-1, in the high-elevation Altai Mountains within NWC. Its CAR shows a decreasing trend, ranging from 4.8 to 68.8 g C m-2 yr-1, with a mean of 28.0 g C m-2 yr-1 since the Holocene epoch. Comparisons of the CAR in the Westerlies-influenced NWC with that in the monsoon-influenced Qinghai-Tibetan Plateau, Northeast China, and South China, reveal that the Holocene CAR trend in relatively high-elevation peat deposits (e.g. Tuolehaite Peat and Hongyuan Peat) is opposite to that found in relatively low-elevation peat deposits (e.g. Hani Peat and Dahu Peat). Different driving factors (temperature and precipitation) of CAR could be responsible for these opposing trends. To be specific, temperature is the main driving factor influencing the CAR in relatively high-elevation peat deposits, whereas precipitation is the key driving factor controlling the CAR in relatively low-elevation peat deposits. Our work indicates that comprehensive investigations into peat CARs in both Westerlies-influenced and monsoon-influenced regions contribute to an understanding of the peat CAR pattern in China as a whole.