Forest soil charcoal and historical land use

Charcoal deposits in forest soils have been considered mainly in the context of wildfires. However, slash-and-burn cultivation has been widespread in Northern Europe until the beginning of the 20th century and extensive areas of former swiddens are now covered by forests. The study sites were in Karula National Park in Southern Estonia. 19th-century cadastral maps were used to identify the historical land use. Macroscopic (visible) charcoal was studied in 57 soil pits, located in historical slash-and-burn sites, forests, former arable fields, recent forest fire sites, and experimental slash-and-burn fields. The locations of charcoal in the soil profile were recorded. In four sites, the charcoal samples were dated. Charcoal is widespread in boreal forest soils. A considerable proportion of this could originate from historical slash-and-burn cultivation. The charcoal depth was related to agricultural land use duration and methods at different intensities. The location of the charcoal-rich layer reflected the historical cultivation best, though patchy spatial distribution and the evident translocation of charcoal from different fire events complicates the interpretation of the charcoal pattern. Not all translocation mechanisms have yet been explained.