Post-fire dispersal characteristics of charcoal particles in the Daxing'an Mountains of north-east China and their implications for reconstructing past fire activities

A wildfire with many ignition points took place in the Daxing’an Mountains of north-east China in June 2010. After the fire, moss polsters and particle traps were collected from burnt and unburnt areas a few kilometres away from four ignition points. Charcoal extracted from the samples was divided into macroscopic charcoal >125 μm and microscopic charcoal <125 μm. Our results showed that the average amount of charcoal deposited in the burnt areas was statistically greater than the amount deposited in unburnt areas. The microscopic charcoal concentration inside the burnt areas rose as the size of the burnt area increased. However, the sampling points within the largest burnt area did not have the highest macroscopic charcoal concentration. We found that only limited amounts of charcoal were transported over a long distance and that the primary charcoal produced during or shortly after a fire event was much more abundant than the secondary charcoal produced during the non-fire period. This suggested that primary charcoal is the dominant signal in charcoal records, and that the charcoal Z-score values inside the burnt areas were clearly higher than the surroundings. Our observations indicate that multiple-size charcoal records may be a robust tool for reconstructing fire histories.