Økosystemer i endring : tidlig jordbrukspåvirkning innen kystlyngheibeltet i Sørvest-Norge

Abstract

Palynological data collected over a period of 60 years have been compiled and re-interpreted in order to reveal the deforestation patterns in the southwestern Norwegian coastal heathland. PCA- is used to study the ecological aspects of the deforestation process. Deforestation follows a regional pattern connected to the geological and topographical quality of the land, but all areas end up in heathland and/or grassland and permanent infields regardless of geographical differences. In the Karmøy-Boknafjord region (region A) some localities show early human impact with an intermediate semi-stationary stage of great stability where elm (Ulmus), ash (Fraxinus), lime (Tilia) and partly hazel (Corylus) have been favoured. This stage may reflect a farming practice mainly based on cattle where fodder from broadleaved trees was important. Pollen from cereals occurs, but is scarce. At Lista (region D) however, although there are signs of early human impact, a correlation between broadleaved and open field species is not clearly pronounced. This because the initial forest, prior to the clearing, mainly consisted of broadleaved species and had to be removed anyway. In this region, a mixed economy based on both animal husbandry and cereal cultivation was established by the Middle Neolithic. The final establishment of heathland was presumably a result of a shift in farming practice from diversified intensive farming to extensive grazing. This is most clearly seen in the Jæren region (region B).