Application of aerial photographs for the assessment of anthropogenic denudation impact on soil cover of the Brodnica Landscape Park plateau areas

Abstract

The aim of the study was to assess suitability of colour aerial photographs for mapping of soil cover transformed due to effect of anthropogenic denudation. The investigation was carried out in south-western part of the Brodnica Landscape Park, within the boundaries of rolling and hilly moraine plateau, used for agricultural purposes. The soil cover of that area is exposed to intensive influence of slope processes triggered by human agricultural activity. The anthropogenic denudation leads to truncation of soil profiles of top convex sections of slopes and hills’ summits. Soil material moved down the slopes is accumulated in the form of diluvium in hollows and lower sections of slopes. Two study sites were selected – Sumówko and Zbiczno. Within the boundaries of both study sites, detailed soil mapping took place consisting in preparation of irregular boreholes projection. Next, four sites were selected for soil pits, representing broad spectrum of transformations related to anthropogenic denudation. Based on obtained results and colour diversity of surface horizons, the spatial range of individual soil types was specified. It also enabled determination of anthropogenic denudation impact on formation of the soil cover. Totally eroded soils, classified as pelosols, located on hills’ summits, are characterized by very bright colours of surface horizons, resulting from content of calcium carbonate in glacial tills. The range of soil lessivés, prevailing within the slopes boundaries, where the erosion resulted in exposure of argic horizons rich in iron compounds and clay fraction, coincided with occurrence of brown colours. Bright grey surface horizons are characteristic of deluvial soils. This colour arises from sandy texture of deluvial material (low content of iron) in combination with humus nature. The soils located in relatively vast field depressions were covered with small thickness of diluvium, which was reflected in dark grey colours of surface horizons. These horizons are relatively rich in soil humus. Significant amounts of humus are related with mix of deluvial material with material formed in humus horizons, originally occurring on surfaces of soils rich in organic matter – black earths and organic soils.