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 our own research, concerning carbon stocks in soils of coastal zone ecosystems: marshes and seagrasses 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 in the 0–10 cm layer of marsh soils were 34.3 ± 21.5 t/ha, and the aquatic soils of marine meadows were 7.8 ± 6.5 t/ha. As a rule, carbon reserves in soils directly depend on the productivity of phytocenosis. A positive dependence of carbon stock on seawater temperature has been established. It is shown that with increasing salinity of water, carbon reserves in the soils of marshes decrease, while in marine meadows they increase. On the shores, carbon reserves are maximal in the soils of the rarely flooded high marsh. In the mineral soils of the marshes, higher carbon reserves are observed in heavy-textured soils than in less clayey soils. High carbon reserves in sandy–sandy loam soils are commonly found in the soils of marine meadows. The results of the study can be used to assess the impact of coastal ecosystems on the content, dynamics and potential for carbon absorption, climate change, and serve as a basis for developing measures for the protection and rational use of natural resources in coastal landscapes.