Matching Estonian humus cover types' (pro humus forms') and soils' classifications

For characterization of soil cover influence on formation and functioning of ecosystems, the special attention should be paid to its biologically active superficial part i.e. to the humus cover (HC). The used by us term 'HC type' corresponds well to the internationally recognized term 'humus form'. The fabric of the HC is characterized by the humus profile, which consists of the organic matter-rich soil horizons (forest floor, humus, organo-mineral and peat horizons). For the basis of comparative analysis, the classification schemas, elaborated separately for natural area HCs and soils, were used. In both schemas, the classification units are arranged according to soils moisture conditions and genesis. A good coincidence of HCs' and soils' types was obtained in relation to moisture scalar. The four first stages of moisture conditions enfold soils, in which the leading role belongs to the mineral components of the soil. The fifth column enfolds the transitional HC types between mineral and peat soils, whereas the typical peat soils are located in the 6th column. The genetic-lithic scalar shows that the calci-mull HCs have formed on soils rich in free calcium carbonate; forest-mull on calcareous pebble and leached soils; moder-mull on slightly eluviated endocalcareoussoils; moder types - on glossic and sod-podzolic soils; moder-mor on transitional podzols (between sod-podzolic and typical podzols) and mor type HCs on typical podzols. HCs in the 1st column (drought-timid soils) are divided according to their calcareousness and acidity, but those in the 5th and 6th columns (peaty and peat soils) - according to the content of nutrition elements in the feeding water, into 3 types. The matching of classification units of HCs and soils are analysed as well on the basis of the soils matrix table.