Lake Belau and its catchment (northern Germany): A key archive of environmental history in northern central Europe since the onset of agriculture

Abstract

The environmental history since the onset of agriculture was reconstructed from sediments and soils in the catchment area of Lake Belau (Schleswig-Holstein, northern Germany). The established chronologies are based on varve counts, radiocarbon data, embedded Icelandic tephra (lake sediments), radiocarbon dates, and embedded artifacts (slope deposits). Neolithic land use triggered small-scale erosion. Lake trophic indicators and pollen data clearly reflect the onset of agriculture and the middle Neolithic expansion of agricultural activity. Despite numerous archaeological findings, less intensive field use and no soil erosion occurred during the older and younger Bronze Age. Perhaps, animal husbandry was more important than cereal cultivation. Between 2000 and 500 cal. bc, Aeolian input from a distant source can be observed. During the late Bronze Age and Pre-Roman Iron Age, intensified field use enabled severe soil erosion (gullies c. 200 cal. bc). The degradation of soils started in this period, influenced by excessive land use, climatic variability, and/or the reduction in Aeolian deposition. The Roman Iron Age and Migration Period were phases of reduced human impact and soil formation. During medieval times, the intensity of field use increased again and another phase of soil erosion (gully in the 14th century, probably reflecting the ‘Magdalenenflut’ 1342) and soil degradation started. After the late medieval crisis caused by the ‘black death’ and several armed conflicts, another increase in soil erosion may reflect the rearrangement of estates (18th−19th century) and introduction of industrial agriculture (20th century). A recurrence of high-intensity erosion events is indicated at c. 1540, 1710, and probably 1939 ad. Whereas the lake trophic status is influenced by human impact on the lake catchment, wetter and warmer climatic phases are reflected in increased carbonate precipitation modulated by solar activity, human impact, and the long-term evolution of vegetation and soils in the lake catchment.