Water-extractable organic compounds in different components of the litter layer of boreal coniferous forest soils along a climatic gradient

We investigated the concentrations and stocks of water-extractable carbon (WEC), nitrogen (WEN), phenolics and sugars in the main litter types (tree, dwarf shrub, moss) in boreal forests on two site types (mesic Norway spruce and sub-xeric Scots pine forests) in the south and north boreal climatic zones. WEC, sugar, and phenolic concentrations in the dwarf shrub and tree litter were higher in the north, whereas WEC and phenolic concentrations in the moss litter were higher in the south. Trees, dwarf shrubs, and mosses contributed to a varying extent to soil WEOM in the north and south boreal forests, the trees accounting for a major part of the WEOM in the south, but the understorey dwarf shrubs in the north. WEOM stocks were not predominantly determined by the concentrations of water-extractable compounds in each litter type, but instead by the quantitative proportions of the individual litter types.