Charcoal Dispersal from Alpine Stallo Hearths in Sub-Arctic Sweden: Patterns Observed from Soil Analysis and Experimental Burning

Abstract

To evaluate dispersal patterns and concentrations of macroscopic charcoal particles around Stállo settlements in sub-arctic Scandinavia, their distributions following experimental burning and soil concentrations around an alpine Stállo settlement dating between AD 700 and 1150 were recorded. After the burning 98% of recorded particles were 0.1-0.5 mm long, 90% were dispersed within 40 m of the fire, their mean concentration 40 m from the fire was 0.14±0.08 particles/cm 2 and the concentration decreased with increasing distance. At the settlement, 95% of recorded charcoal particles were 0.1-0.5 mm long, 94% were within 40 m of the hearths, the mean concentration declined with increasing distance, and concentrations were much lower than expected from the experimental burning (e.g. 17.6±2.4 particles/cm 2 , 40 m away). In conclusion: biological archives used for charcoal analysis in archaeological and vegetation history studies should be located ≤40 m from settlements, and data obtained from charcoal analyses should be interpreted cautiously.

Intensive land use in the Swedish mountains between AD 800 and 1200 led to deforestation and ecosystem transformation with long-lasting effects

“…There were no peaks in the fossil charcoal records established by Karlsson et al (2007), which would indicate large fire events, and the charred particles were too few to correspond to a substantial reduction of the tree cover. Rather, this fossil charcoal seems to derive from fires made in the huts as indicated by experimental studies of charcoal dispersal in this area (see Hörnberg and Liedgren 2012). Furthermore, a single fire event might cause deforestation, but regeneration follows as a result of the fact that only about half of the N is lost from the O horizon in a single fire event (unless it is unusually severe) and basically none is lost from the surface mineral soils (Smithwick et al 2005).…”