Studies on the soils in forest ecosystems in breaks of the rivers Jeleń and Sopot were carried out in the years 1997-1998. Although the rivers differ in length, catchment area, amount of water carried and breadth of the valleys, the most important factors affecting soil formation and their spatial differentiation are similar: bedrock, relief, water drainage, natural type of water management, position of the ground water-table relative to the river water level, and chemistry of spring and soil waters. Steep slopes of the valleys covered with poor and highly acidic podzolic soils are usually overgrown with fir and pine phytocenoses, or rarely, with mixed oak-pine forests. The bottoms are often characterised by longitudinal duality of the flood-plain benches. In the drier area close to the river beds under ash-alder forests, there are more fertile gley soils and gley podzols. Poorer and more acidic localities are occupied by mixed forests with spruce. In permanently moist fragments of the benches at the foot of the slopes and in depressions with stagnant water weakly acidic peat-mud and peat soils occur overgrown with bog-alder forests. Peculiarities of these areas are low peat-bogs suspended even up to 4-6 m above the water-table of the river.