Palaeoecological investigations towards the reconstruction of the history of forest clearances and coastal heathlands in south-western Norway

Palynological data collected over a period of 60 years have been compiled and re-interpreted in order to reveal the patterns of deforestation and health establishment in the south-western Norwegian coastal heathland. This heathland area has been divided into four sub-regions based on topography, bedrock and drift cover. The palynological investigations are from sites with pollen source areas of different sizes. The palynological signals are interpreted in terms of models that suggest an abrupt, gradual or stepwise deforestation which can be explained by terms of different pollen source areas. The deforestation seems to have been metachronous, leading to a regional mosaic pattern of different vegetation types. The deforestation process spanned more than 3600 calendar years (4000-400 B.C.), with three pronounced clearance periods at 4000-3600 B.C. (Mesolithic/Early Neolithic transition), 2500-2200 B.C. (Middle Neolithic II/Early Late Neolithic transition), and 1900-1400 B.C. (Late Neolithic to Bronze Age period II). The expansion of heathland has also been metachronous and took place over a period of ca. 4000 years between 4000-200 B.C., but was mainly completed by the end of the Bronze Age. Regional differences in the chronology of deforestation and heathland establishment are discussed. Deforestation with subsequent heathland expansion can best be explained in terms of the interaction between land-use history, topography and edaphic conditions under climatic conditions that favoured heathland development.