Long-distance transport of macroscopic charcoal by an intensive crown fire in the Swiss Alps - implications for fire history reconstruction

Abstract

The correct interpretation of charcoal records in a palaeoecological context requires the understanding of the sources and transport of charcoal particles. Conventionally, it is assumed that macroscopic charcoal particles are not transported far from fires ( c. 200m). Therefore macroscopic charcoal records are used to reconstruct local fire frequencies. However, the general scarcity of empirical and experimental evidence impedes a thorough check of this assumption. In this study we present the first unambiguous evidence of kilometre-scaled macroscopic charcoal transport in Europe. During the hot summer of 2003 an intensive crown fire occurred in Leuk, central Swiss Alps. It affected 300 ha of forest as well as 10 ha of pasture and fallow land. Litter traps and nets had been located approximately 5 km west and east of the burned area. The downwind site in the east (Jeizinen) recorded a strong charcoal fallout at 5.3 km from the fire edge. The observed charcoal influx of fragments with a size up to 1.3 cm reached average values of 0.144 and 0.098 mm2/Cm2 per fire (or yr) in five traps and two nets, respectively. These values are comparable with charcoal accumulations measured at only c. 50 m from large fires, suggesting that macroscopic charcoal transport does not decay rapidly to zero with increasing distance from the fire. We suggest a long-distance dispersal model for transport of macroscopic charcoal during large fire events. Reconstructions of local fire regimes may be affected by long-distance transport of macroscopic charcoal, although this problem is mitigated by the tendency of most macroscopic charcoal particles to be deposited within very short distances (< 50 m) from the fire edge.

A continuous record of fire covering the last 10,500 calendar years from southern Sweden — The role of climate and human activities

“…The theoretical results of Peters and Higuera (2007) also suggest that macroscopic charcoal, even though strongly biased towards short distances, may travel many kilometres, which is consistent with dispersal data from uncontrolled fires (e.g. Whitlock and Millspaugh, 1996;Pisaric, 2002;Hallett et al, 2003;Tinner et al, 2006).…”

“…More recent studies were performed in the Southern Alps (e.g. Tinner et al, 1999;Tinner et al, 2006;Colombaroli et al, 2008). While studies in America and Australia discuss the fire-climate relationships (e.g.…”

Reconstructions of biomass burning from sediment-charcoal records to improve data–model comparisons

“…Uncertainties in charcoal records also come from the many natural processes related to charcoal production, transportation, and deposition, which interact to produce variability in charcoal accumulation over time. These processes are being studied through field experiments and calibration studies that will enable the development of higher quality fire-history reconstructions and a better understanding of uncertainties (Tinner et al, 2006;Higuera et al, 2011;Aleman et al, 2013). An important source of uncertainty in global fire models is the parameterization of the processes most directly controlling fire activity (e.g., human influence, climate influence; e.g., Pechony and Shindell, 2009;Pfeiffer et al, 2013).…”

Modern pollen data from pristine taiga forest of Pechora-Ilych state nature biosphere reserve (Komi republic, Russia): first results

“…Microcharcoal particles were found in amount 4-8% from total pollen sum. They are clearly detect local forest fire of 2004 located within 3.5 km from sampling points (Tinner 2006). The pollen grains of ferns (Dryopteris type, Gymnocarpium type), herb plants (Poaceae, Ranunculus type, Cyperaceae, Acteraceae, Rosaceae) and dwarf shrubs (Ericaceae) are also present in modern spectra.…”