Permafrost Peatland Initiation and Development in Late Holocene of the Northeast China.

Peatlands play an important role in the global carbon cycle. However, the initiation and development of permafrost peatlands and their responses to climate change remain unclear, hindering our understanding of the past and future of this region. In this study, we reconstructed the evolution of permafrost peatlands in the Greater Khingan Mountains (GKM) of Northeast China since 3500 cal yr BP using palynological evidence from permafrost peatland core and AMSC dating. The results indicated that from 3500 to 2900 cal yr BP, the vegetation mainly composed of , thermophilic broad-leaved trees, and Polypodiaceae, with a warm and wet climate constituting the peatland incubation period. From 2900 to 2250 cal yr BP, the vegetation mainly composed of , thermophilic broad-leaved trees, and , with a peatland initiation period characterized by a warm and humid climate. From 2250 to 1650 cal yr BP, the vegetation mainly composed of , , and Polypodiaceae, with a cold and wet climate allowing peatland to flourish. From 1650 to 750 cal yr BP, the vegetation mainly composed of and , and a dry, cold climate led to a slowdown or stagnation in peatland development. Later in this period, a warmer and wetter climate allowed the peatland to develop again, thereby completing the transition from eutrophic to mesotrophic state. Since 750 cal yr BP, the vegetation mainly composed of and Cyperaceae, indicating a colder and wetter climate allowing the peatland to flourish again, and peatlands began to change to oligotrophic state. Our results showed that the evolution of the GKM permafrost peatlands is mainly influenced by climate, and permafrost peatland development in the future will depend on trends in global climate.