摘要：A region of western Siberia is vulnerable to the predicted climatic change which may
induce an important modification to the carbon balance in wetland ecosystems. This study
focuses on the evaluation of both the long-term and contemporary trends of peat (carbon)
accumulation and its patterns at the southern climatic range of Sphagnum peatlands in
western Siberia. Visible and physical features of peat and detailed reconstructions of
successional change (or sediment stratigraphies) were analysed at two types of
forest–peatland ecotones, which are situated close to each other but differ by topography
and composition of their plant communities. Our results suggest that Siberian
peatlands exhibit a general trend towards being a carbon sink rather than a source
even at or near the southern limit of their distribution. Furthermore, two types
of peat accumulation were detected in the study area, namely persistent and
intermittent. As opposed to persistent peat accumulation, the intermittent one
is characterized by the recurrent degradation of the upper peat layers at the
marginal parts of raised bogs. Persistent peat accumulation is the case for the
majority of Sphagnum peatlands under current climatic conditions. It might be
assumed that more peat will accumulate under the 'increased precipitation' scenarios
of global warming, although intermittent peat accumulation could result in the
eventual drying that may change peatlands from carbon sinks to carbon sources.
