Fractional composition of humus in selected forest soils in the Karkonosze Mountains

This paper describes the fractions of humus compounds present in the organic and mineral horizons of the forest soils in the area of the Karkonosze Mountains. Soil profiles that represented the mountain Podzols and Dystric Cambisol were located on the northern slope along an altitude gradient from 890 to 1255 m a.s.l. Two soils were located under the spruce forest, and one in the subalpine meadow. Soil samples were taken both from the surface organic layers (the ectohumus layer) and from the mineral horizons. Fractionation of humus compounds was made using the modified Turin method. The soils had the texture of loamy sand and sandy loam, an acidic or strongly acidic reaction, low base saturation, and the predomination of aluminum among exchangeable cations. A significant increase in the fulvic fraction (Ia) with depth in the soil profiles was observed that confirmed the high mobility of this fraction in the acid mountain soils, higher in the forest soils, and lower in the meadow soi...