Abrupt forest ecosystem change in SW Sweden during the late Holocene

Abstract

A peat profile from a small raised bog, situated in SW Sweden, was studied for insect, pollen and charcoal analyses in order to reconstruct the late-Holocene forest history of the area. The palaeoecological records cover the last 3700 cal. years. The results were compared with archaeological data, historical documents and palaeoclimate reconstructions from the region. From 1650 cal. yr BC to AD 1310 cal. yr, the study area was characterized by deciduous woodland with a diverse invertebrate fauna. The recorded insects indicate a relatively open or mosaic forest environment with abundance of dead wood. This forest environment was probably maintained by disturbances such as cattle grazing, fire, wood coppicing and small-scale cultivation. At around AD 1310, a major and rapid change in the forest ecosystem occurred, ie, species-rich deciduous woodland was replaced by a species-poor beech forest. The data indicate that a change in land use was the likely reason for the shift in forest type. Grazing and fire ceased, while tree cutting increased. The shift in land use correlates well with political—societal changes in the region during Mediaeval time. Climate changes seem to have influenced the wetland environment, but there is no obvious correlation between major or minor shifts in forest ecosystem and reconstructed climate changes. Today, nature conservationists regard the beech forests of Halland as remains of primeval forests hosting a unique flora and fauna. Our results give new insights and challenge that view.