Climatic changes control the net carbon sequestration rates of Carex-dominated peatlands in Northeast Asia

Carex-dominated peatlands, which are widely developed in Northeast Asia, are one of the planet's most important carbon sinks, playing a key role in controlling the global carbon cycle. However, our understanding of how net carbon sequestration processes are linked to climatic changes for the modern tussock stage (MTS) and the under tussock stage (UTS) of Carex-dominated peatlands remain unclear. In this study, we systematically investigated the carbon sequestration history and its climatic factors potentially driving these changes in the Xinqing peatland from the Lesser Khingan mountains of Northeast Asia. Results suggest that this peatland initiated development prior to 1348 cal yr BP and then evolved into the modern tussock. The average apparent carbon accumulation rate (ACAR) and the net carbon accumulation rate (NCAR) of the MTS was 261.57 g C/m2 yr and 8.58 g C/m2 yr, while the average ACAR and NCAR of the UTS was 16.90 g C/m2 yr and -0.43 g C/m2 yr, respectively. Furthermore, the high efficient net carbon sequestration modes of these two stages can be identified as follows: The first mode was a precipitation-controlled mode. The nutrient input linked to precipitation was the major driving factor for the highly efficient net carbon sequestration of the UTS. Precipitation increased the nutrient input, promoting the increase in productivity of the Carex community, resulting in the high NCAR of the UTS. The second mode was a temperature-controlled mode. With total solar irradiance being the major driving factor for the high efficient net carbon sequestration of the MTS, the increased temperature contributed to the high productivity of the Carex community, resulting in the high NCAR of the MTS. These results add to our understandings of the connections between climatic changes and net carbon sequestration abilities of Carexdominated peatlands, which may provide an important foundation for future predictions on the carbon sequestration potential of these types of peatlands world-wide.