Lateral extension in Sphagnum mires along the southern margin of the boreal region, Western Siberia

Although recent studies have recognized Northern Eurasian ecosystems as an important carbon reservoir, little is known about the forest-peatland interactions in a boreal environment induced by ongoing climatic changes. This study focuses on the evaluation of both the long-term and contemporary trends of land-cover changes and rates of lateral extension of peat-accumulating wetlands toward the adjacent forests, estimated at the southern climatic range of the Sphagnum-dominated mires in Western Siberia. We used the radiocarbon dates and stratigraphy of peat sediments from seven peat cores, analyzed at two types of forest-peatland ecotones, which are located close to each other but differ by topography and composition of their plant communities. The rate of lateral extension was found in a wide range varying from 2.3 to 791.7cmyr^-1. It was observed to be rapid during the initial stage of mire development, but to have slowed down over the last 2000-3000yr. Our results, therefore, strongly contradict the concept of progressive peat accumulation throughout the late Holocene and contribute to our knowledge about ongoing land-cover change in the natural ecosystems of the Northern hemisphere.