Evidence of prehistoric and early medieval agriculture and its impact on soil and land relief transformation in the Białowieża natural forest (NE Poland)

Abstract

The Białowieża Forest is one of the few relics of temperate, old-growth woodlands in Europe considered “natural”. Recent research revealed there the presence of numerous anthropogenic landforms associated with prehistoric, medieval and modern-era human activities. They include systems of rectangular plots separated by embankments – linear forms up to several dozen centimetres high, well distinctive in airborne laser scanning visualizations but relatively poorly visible in the landscape. The field system at the archaeological site of Postołowo, located on a gentle slope currently entirely covered by a mixed forest (Carpinion betuli dominant), was selected for detailed study. The soils of the former arable fields and field boundary embankments were investigated using a multi-proxy approach, including analyses of soil micromorphology, soil physical and chemical properties, as well as sedimentological, archaeological, plant macro-remains and phytolith studies and radiocarbon dating. The objectives were to assess the impact of suspected past agriculture on soils and land relief and to establish a chronology of land use. Evidence of ancient vegetation clearance by burning was confirmed and two distinct episodes of cereal cultivation (including rye), without intensive manuring were dated in the Roman Period (ca 2nd century AD) and in the Early Middle Ages (ca 10th century AD). In the latter case, agriculture triggered soil erosion that led to accumulation of slope deposits; at least some of the field banks accumulated and/or were constructed during this period. Altogether, past agriculture resulted in spatial differentiation of soil morphology: with Brunic Arenosols in the upper parts of the slope and Brunic Umbrisols downslope. It is hypothesized that ancient cultivation in the Białowieża Forest evidenced by the remains of field systems, was limited to relatively short chronological periods and was restricted to certain land patches (microregions) surrounded by unused, forested terrain.