THE SPATIO-TEMPORAL HISTORY OF PEATLAND DEVELOPMENT IN THE WESTERN SIBERIAN LOWLANDS AND A CIRCUMARCTIC PERSPECTIVE ON THE DEVELOPMENT OF SUBARCTIC PEATLANDS AND THEIR INFLUENCE ON REGIONAL LANDSCAPES AND GLOBAL ATMOSPHERIC METHANE CONCENTRATIONS

Northern peatlands are an important landscape component across the subarctic zone of the northern hemisphere. The largest northern peatland complex is found in the Western Siberian Lowlands (WSL) and covers some 600,000 km2. The development of high latitude peatlands was an important component in postglacial landscape development and significantly impacted the hydrology, vegetation, fauna and human occupants of the subarctic. In addition, peatland development influenced atmospheric carbon concentrations through the opposing impacts of sequestering carbon and generating methane. The WSL may account for 26% of total global soil carbon accumulation. Understanding the temporal and spatial history of high latitude peatland development is critical to understanding the environmental history of the subarctic and the history and dynamics of atmospheric carbon concentrations. We radiocarbon dated the basal peats from 87 new cores taken from 60 N to the Arctic coastline in the WSL. Combined with existing Russian dates this provided over 100 age estimates for the initial development of peatlands in the WSL. In order to develop a circumpolar history of peatland initiation we collated published basal radiocarbon dates from subarctic peatlands in North America and Eurasia. The results indicate that subarctic peatland development commenced in the early Holocene- by around 11,500-11,000 CAL yr BP in the WSL and some ice-free areas of North America. A strong peak in peatland initiation in the WSL between 11,500 and 9000 CAL yr BP coincides with increased levels of methane derived from high latitude sources in the northern hemisphere that is apparent in ice core records. This period of initial peatland development also coincides with the development of northern boreal forest in Siberia. The early period of peatland initiation is coincidental with final mammoth extinction in continental Siberia and the development of boreal forest – peatland complexes with low nutritional value for mammoths may have contributed to the extinction. Peatland initiation in the WSL does not show a strong latitudinal or longitudinal pattern. In contrast, the southern fringes of the current peatland zone in central Canada mainly developed in the late Holocene.