Natural variability of pseudogley forest soils in the Białowieża National Park was characterised on the basis of five soil exposures. Two of them were located in a water-logged site, one in a mound one in a patch with dominance of deciduous trees, and one in a spruce biogrup. It was found that pseudogley soils of a natural moist deciduous forest show additional differentiation in the form of characteristic micromosaics. There is a pronounced impact of the species structure in a treestand, uprooted trees and hoofed mammals on the properties of the soil cover. Changes resulting from the above biotic factors were observed in all the analysed physical, physico-chemical and chemical soil parameters.