Western Siberian Peatlands As Indicator and Regulator of Climate Change on Global Scale through Feedbacks with Carbon Effluxes

Abstract:

The Western Siberian plain (WSP) is the most bogged region of the World - in some parts up to 70-80% of its territory is covered by bogs, in overall 1 million km². Western Siberia acts as a terrestrial sink of atmospheric carbon and thus plays an important role in the global cycle of carbon. For thousands of years the vast taiga forest and pristine peatland areas south of the permafrost area have been sequestrating substantial amounts of atmospheric carbon. The biggest at the World – Great Vasiugan Mire GVM (total area – 7.5 million hectare settles down in its territory. This unique mire representing the object of a nature of the world value, comparable on the importance and a rank with the lake Baikal. The peat stock accumulated in the GVM is around 18 billion tons of dry organic matter, representing 16.5% of total peat stock deposits in the WSP (Vaganov etc., 2005). According to our investigations carried out in the Western Siberian Plain, contrasting processes are occurring in the Southern and Northern parts of the region. In the south, bogs are expanding in the taiga zone and there is progressive swamping which leads to forest death. As a result, in this part of Western Siberia bogs act as a kind of “global cooler” due to carbon sequestration in their peat layers. The situation in the northern part of the Western Siberian Plain is completely opposite. The bogs there are reducing their area and the forest-tundra area is being subjected to thermokarst activity and colonization of bogs by trees. Due to incredibly increased thermokarst activity, two contrast processes are observed here - a) increase of lake surface due to melting of lakes' coasts, and - b) decrease of surface area or disappearance of lakes due to water escape downstream the hydrological network. Moreover, thermokarst processes increase carbon effluxes, especially from the small lakes. This is likely to be linked to the recent climatic changes and, undoubtedly, with global warming.