EN
Investigation of chemical composition of raw humus were fulfilled in Bory Tucholskie in accordance to a contract with National Park authority. The area of case study is about 50 km² and includes sander plain, covered by pine coniferous forest with moss and lichen Cladonia undergrowth. The dominant parent rock of rusty soils is loose sand. Actual development of flora composition is mainly determined by nutrients from raw humus and atmospheric precipitation. Raw humus type is moder and moder-mor. Sublayer Of containes around 33,4% C and 1,12% N, but Ofh-30,7% C and 1,26% N. The organic whole layer on the area of 1 m² contains around 50g N, 3,7 g K, 2,7 g Fe, 0,1 g Cu. Atmospheric precipitation at the level of 478 mm annually (year 2001) consists another important source of nutrients for the local ecosystems. For example: atmospheric input brings 5% of N and even 85% of Mg in the raw humus. Distribution of these proportions may impact on eutrophisation of protected habitats in the Park.