Enhanced climate control on carbon accumulation dynamics in Sihe peatland, Northeast China, over the past 2200 years

Peatlands are vital terrestrial carbon sinks because of their exceptional carbon sequestration capacity. Understanding the processes and factors influencing carbon accumulation is critical for elucidating the principles governing peatland carbon dynamics, thereby supporting global climate change mitigation efforts. This study reconstructed the carbon accumulation history of the Sihe (SH) peatland, a minerotrophic fen in the Changbai Mountains of northeastern China, over the past 2200 years. Carbon stable isotopes (δ¹³C) of α-cellulose in Carex spp. and grain-size-sensitive components were identified as effective indicators of peatland moisture and hydrological conditions, whereas plant macrofossil analysis was performed to track the temporal changes in vegetation composition. The results indicated that the moisture condition and hydrological supply in the SH peatland have exhibited a declining trend over the past 2200 years, reflecting a strong sensitivity to centennial-scale variations in precipitation and humidity within the Changbai Mountains. During the Roman Warm Period (RWP) and the Dark Age Cold Period (DACP), despite higher summer solar insolation, greater seasonality, elevated regional temperatures, and abundant precipitation, the CAR in the SH peatland remained relatively low. This suggested that the influence of climate on CAR was constrained by other factors. During the Medieval Warm Period (MWP) and Little Ice Age (LIA), climate had a pronounced impact on CAR. Under warm and humid conditions, peatlands exhibited an elevated CAR, whereas the cold and arid conditions of the LIA led to a significant decline. Notably, the CAR of the SH peatland demonstrated no significant response to local moisture, indicating a complex relationship between hydrological conditions and carbon accumulation dynamics. This study emphasized that climate could not always be the primary driver of CAR in peatlands, with vegetation composition and local autogenic processes playing critical roles. However, the influence of climate on carbon accumulation dynamics may intensify as the peat layers accumulate.