HUMAN IMPACT AND FIRE-REGIMES IN SOUTHERN SWEDEN INTERPRETED FROM TERRESTRIAL MACROSCOPIC CHARCOAL

In spite of its great potential, terrestrial macroscopic charcoal from soil profiles are rarely used in palaeoecological studies of human impact and land-use practises. The main reason for this may be that soil profiles usually are disturbed by bio-turbation, and that each piece of charcoal therefore has to be individually radiocarbon-dated in order to get reliable chronologies. Among the advantages of terrestrial macroscopic charcoal, in comparison to microscopic charcoal from lake and peat sequences, is that it is of very local origin and that it can be wood-anatomically identified to species or genera.

In connection to a series of archaeological excavations in southern Sweden, macroscopic charcoal was sampled from soil profiles in areas with traces of Iron Age agriculture. The sampled charcoal was wood-anatomically identified, and all together 150 pieces were radiocarbon-dated within the project. The results give new information on the long-term fire-history of southern Sweden, from early-Holocene natural fires in Pinus woodlands, to anthropogenic fires in cultural landscapes. It gives new and detailed in-sights into the process of agrarian expansion and, in particular, the role of fire in forest clearances and in the maintenance of semi-open pastures and cultivated plots. The result show that the use of fire during the Iron Age can be divided into two succeeding phases: expansion and maintenance. In the expansion phase, fire was used to turn semi-natural Quercus-woodland to open land used for grazing and cultivation. In the following phase, fire was used primarily to keep pastures open by clearing secondary-succession trees and shrubs of Betula and Corylus. By comparing the results with local and regional pollen diagrams it is possible to link specific pollen zones to Iron Age land-use practises and fire-regimes.