Comparison of sedimentary microscopic charcoal particle records in a small lake with dendrochronological data:: evidence for the local origin of microscopic charcoal produced by forest fires of low intensity in eastern Finland

Dendrochronological data and microscopic charcoal particle series from annually laminated lake sediment covering the past 520 years were compared. Slash-and-burn cultivation had been practised in the area (63 degrees 10'N, 30 degrees 58'E) for about 300 years during this period, causing a considerable increase in the number of forest fires. The fire years based on fire-scar data coincided with peaks in the microscopic charcoal series, suggesting that a significant proportion of charcoal particles usually counted on pollen slides can originate from local fires or fires within a few kilometres of the sampling point. Thus, contrary to the theories of charcoal particle transport, the abundance of microscopic charcoal may indicate, in some cases, fires at close quarters better than at a regional or broader spatial scale. Regional sources contribute to the microscopic charcoal records, but an increase in the proportion of largest particles and a decrease in particle size c. < 10 mu m in diameter suggest local burning. The result may be due to fires of a low-intensity in the area. The particles collected during an experimental low-intensity burn supported the results obtained from the sediment samples. The majority of the particles collected were of the same sizes that are most abundant on pollen slides.