Stocks of “Blue Carbon” in Soils of Coastal Ecosystems of High-Latitude Seas of the Northern Hemisphere

The article presents a review of data from Russian and foreign sources, as well as of our own research, concerning carbon stocks in soils of coastal zone ecosystems: marshes and seagrass meadows of the USA, Canada, Great Britain, continental Europe, Scandinavia and Greenland, as well as Russia. These soils are formed under conditions of amphibious water regime and are mainly classified as Tidalic Fluvisols. The mean values of carbon stock were 34.3 ± 21.5 t/ha in the 0–10 cm layer of marsh soils, and 7.8 ± 6.5 t/ha in the aquatic soils of seagrass meadows. Carbon stocks in soils, as a rule, directly depend on the productivity of phytocenosis. Carbon stock was shown to be positively dependent on seawater temperature. It is also shown that with increasing salinity of water, carbon stocks in the soils of marshes decrease, while in seagrass meadows they increase. On the shore, carbon stocks are maximum in soils of the rarely flooded high marsh. In the mineral soils of the marshes, carbon stocks are higher in heavy-textured soils than in coarse-textured soils. High carbon stocks in loamy–sandy and sandy soils are commonly found in the soils of sea meadows. The results of the study can be used to assess the impact of coastal ecosystems on the content, dynamics, potential for carbon absorption, and climate change, and serve as a basis for measures designed to protect and sustainably use coastal landscapes.