Mid- to late-Holocene land-use change and lake development at Dallund Sø, Denmark: vegetation and land-use history inferred from pollen data

Pollen and plant macrofossil analysis of an 11-m sediment core from Dallund Sø, a lake situated in the plains of north Funen, Denmark, provide a record of the last 7000 years of vegetation history in response to changing land-use practices. Around 3900 BC, a distinct Ulmus decline is registered. The first agricultural activity is evidenced c. 400 years after the elm decline by the occurrence of cereal pollen (Avena/Triticum-type). Shortly after this, the Neolithic 'landnam' sensu Iversen was detected. Around the transition Late Bronze Age/Pre-Roman Iron Age (500 BC), extensive forest clearances followed by a major expansion of grazing areas, cultivated fields and meadows was inferred. The immigration time of Fagus is hard to identify but a threshold percentage > 2 was reached c. 700 BC, suggesting a local presence of Fagus woodland by then. In the Late Iron Age (AD 400-AD 1050), rising abundances of cereal and Cannabis-type pollen indicate increased arable farming. A contemporary Fagus/Quercus woodland expansion may be due to a change in the agricultural system. Linum-retting in the lake in this period is suggested by the macrofossil record. At the beginning of the Mediaeval period, new major deforestation was inferred, accompanied by a massive expansion of arable farming (cereals, Fagopyrum, Linum, Cannabis). Extensive Linum-retting in the Mediaeval period is documented by the macrofossil record and high values of Cannabis-type pollen in the sediments also suggest intensive retting of hemp plants. In the seventeenth and eighteenth centuries the catchment probably witnessed the strongest agricultural impact of the last 7000 years.