Peatland initiation and carbon dynamics in northeast China: links to Holocene climate variability.

Throughout northeast China, the widely distributed peatlands have formed a large carbon (C) pool. However, the relationship between peatland initiation and climate controls is still poorly documented and understood. Understanding the responses of these C-rich ecosystems to past climate change will provide useful insights into projecting the fate of peatland C in the future. In this study, we present a detailed historical reconstruction of peatland development in northeast China based on 312 basal peat dates, and examine the relationship between Holocene peatland dynamics and climate sensitivity. Our results indicate that peatland initiation started in the early Holocene, and that the majority of peatlands were initiated by and developed during the late Holocene. After the most intensive initiation period of 4.2-0.8 ka, the rate of peatland development slowed, which was concomitant with decreasing insolation and monsoon intensity. The widespread peatland initiation in the late Holocene might have been caused by the cool and moist climate patterns. The optimum timing of the peatland development was not uniform across northeast China, and these spatio-temporal differences indicate the influences of regional climate and terrain on peatland initiation. Peat-core data show variations in the long-term apparent rate of C accumulation ( LORCA) during the Holocene, with an average rate of 37.2 g C m−2 a−1. The peak LORCA occurred during 10.5-9.0 ka, probably in response to higher temperatures and stronger East Asia summer monsoon intensities. Both temperature and humidity are important factors influencing the peatland initiation and C dynamics in this region. [ABSTRACT FROM AUTHOR]