Experimental production of charcoal morphologies to discriminate fuel source and fire type: an example from Siberian taiga

• Main Author: Feurdean, Angelica
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: ddc:550; ddc:570; taiga; Siberia
• Online Access: http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/62756; https://nbn-resolving.org/urn:nbn:de:hebis:30:3-627569; https://doi.org/10.5194/bg-2021-1; http://publikationen.ub.uni-frankfurt.de/files/62756/container.zip

The analysis of charcoal fragments in peat and lake sediments is the most widely used approach to reconstruct past biomass burning. With a few exceptions, this method typically relies on the quantification of the total charcoal content of the sediment. To enhance charcoal analyses for the reconstruction of past fire regimes, and to make the method more relevant to studies of both plant evolution and fire management, more information must be extracted from charcoal particles. Here, I burned in the laboratory seven fuel types comprising 17 species from boreal Siberia, and build on published schemes to develop morphometric and finer diagnostic classifications of the experimentally charred particles. As most of the species used in this study are common to Northern Hemisphere forests and peatlands, these results can be directly applicable over a broad geographical scale. Results show that the effect of temperature on charcoal production is fuel dependent. Graminoids and Sphagnum, and wood (trunk) lose the most mass at low burn temperatures, whereas heathland shrub leaves, brown moss, and ferns retain the most mass at high burn temperatures. In contrast to the wood of trunk, the wood of twigs retained their mass at intermediate temperature. This suggests that species with low mass retention at hotter burning temperatures might be underrepresented in the fossil charcoal record. Charred particle aspect ratio (L/W) appeared to be the strongest indicator of the fuel type burnt. Graminoid charcoals are more elongate than those of all other fuel types, leaf charcoals are the shortest and bulkiest, and twig and wood charcoals are intermediate. Finer diagnostic features were the most useful in distinguishing between wood, graminoid, and leaf particles, but further distinctions within these fuel types are difficult. High-aspect-ratio particles dominated by graminoid and Sphagnum morphologies are robust indicators of cooler surface fires. Contrastingly, abundant wood and leaf morphologies and low-aspect-ratio particles likely ...