Soil Carbon Stocks in a Geochemical Landscape of Spruce Forests in Murmansk Region

The article provides the results of assessment of soil carbon stocks in dominant spruce forests of the northern taiga subzone located in the automorphic, transitional, and accumulative elementary landscapes. The influence of mosaic patterns of vegetation is taken into account by identifying dominant elementary biogeoareal (EBGA) in each forest type. The patterns of vertical (by soil horizons) and horizontal (under different elements of ground vegetation) variation of soil carbon stocks in spruce forests have been determined taking into account the location in the geochemical landscape. The highest soil carbon stocks are characteristic of the accumulative landscapes, where peat horizons are formed under hydromorphic conditions; the lowest soil carbon stocks are in the transitional locations on slopes. Regardless of the location in the geochemical landscape, higher amounts of carbon accumulate in the OL subhorizon under tree crowns, which is due to the larger input of fresh litter, and in the OF subhorizon within intercrown spaces, where the contribution of mosses is significant. Carbon stocks in the OH subhorizon are determined by different mechanisms of transformation and migration of organic matter and differ under different EBGAs of elementary landscapes. High carbon stocks in the layer of 0–30 cm are formed in the most productive EBGA of mature (>100 yr) tree stands in the automorphic landscape. The article develops ideas about the influence of structural diversity of vegetation on soil carbon stocks in the northern taiga biogeocenoses.