Soil transformations in catchment of disappearing Sumówko Lake (Brodnickie Lake District, Poland)
Lake disappearing is a natural process which contemporarily escalates in consequence of human activity. It is estimated that within the area of Northern Poland from the last glaciation period (ca. 17 000 years ago) a half of lakes totally have disappeared. Areas exposed after water basins desiccation have become native rocks for new soils. Reduced water level results in changes of morphology and properties of the soils situated in direct vicinity of former water basins. The aim of this study was to estimate impact of the catchment groundwater level fall on morphology and properties of direct lake catchment soils, exemplified by the lake Sumowko (Northern Poland) as well as description of new soils formed of lake sediments. The analysis covered 11 soil profiles emerging within former lake basin (newly formed soils) and soils from direct vicinity of former lake (modified through ground water level fall). Obtained results prove that newly formed soils (Limnic Histosol Drainic and Haplic Gleysol) in majority are utilized as grasslands. Soils of the former lake surroundings prove relic features of gleying while they are also subject to mucking process because of dehydration.
Based on archaeological data and pedological analysis, an attempt was made to reconstruct the functional pattern of a farmstead from the Late Bronze Age at the Ruda site (Northern Poland). Late Bronze Age human activity in the area and immediate vicinity of the homestead led to changes in the chemical properties of the soils. Different values of phosphorus and organic carbon content in the features and cultural layers may help interpretation of the past spatial development and use of the studied households. The areas with the highest concentration are linked with places of intense economic activity, and the small increase in the phosphorus content in the soil from the homestead may suggest a relatively short exploitation of this place, which would correspond with the small number of artefacts from that area. Features similar to the presented Late Bronze Age homestead have not been recorded before in the Polish territory. Analogous spatial assumptions are known from the Carpathian Highlands as well as from the north (German and Scandinavian territories).