Organic Matter and Rate of Modern Carbon Accumulation in Marsh Soils of Southern Sakhalin Island

It has been established that in the coastal zone of Aniva Bay (Sakhalin Island, 46.74° N; 142.73° E) the following soil type change occurs with increasing location above sea level: marsh algal-detrital → marsh detrital → marsh detrital-peat → marsh peat → peat under forest. The results describing for the first time carbon accumulation in marsh soils of the temperate zone under plant communities dominated by Triglochin and Carex genera were obtained. Modern sediment accumulation in Aniva Bay marsh soils proceeds at a high rate, averaging 2.1 cm year−1, accompanied by intensive carbon accumulation, averaging 720 g C m−2 year−1. The found values of carbon accumulation rates are several times higher than the global average rate calculated for marshes soils—244.7 g C m−2 year−1, but do not exceed the known maximum values—1713 g C m−2 year−1.