Fire is a key Earth system process, with 80% of annual fire activity taking place in grassland areas. However, past fire regimes in grassland systems have been difficult to quantify due to challenges in interpreting the charcoal signal in depositional environments. To improve reconstructions of grassland fire regimes, it is essential to assess two key traits: (1) charcoal count, and (2) charcoal shape. In this study, we quantified the number of charcoal pieces in 51 sediment samples of ponds in the Great Plains and tested its relevance as a proxy for the fire regime by examining 13 potential factors influencing charcoal count, including various fire regime components (e.g. the fire frequency, the area burned, and the fire season), vegetation cover and pollen assemblages, and climate variables. We also quantified the width to length (W:L) ratio of charcoal particles, to assess its utility as a proxy of fuel types in grassland environments by direct comparison with vegetation cover and pollen assemblages. Our first conclusion is that charcoal particles produced by grassland fires are smaller than those produced by forest fires. Thus, a mesh size of 120μm as used in forested environments is too large for grassland ecosystems. We recommend counting all charcoal particles over 60μm in grasslands and mixed grass-forest environments to increase the number of samples with useful data. Second, a W:L ratio of 0.5 or smaller appears to be an indicator for fuel types, when vegetation surrounding the site is before composed of at least 40% grassland vegetation. Third, the area burned within 1060m of the depositional environments explained both the count and the area of charcoal particles. Therefore, changes in charcoal count or charcoal area through time indicate a change in area burned. The fire regimes of grassland systems, including both human and climatic influences on fire behavior, can be characterized by long-term charcoal records.
Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape
B. Leys,Julie L. Commerford,K. McLauchlan
Published 2017 in PLoS ONE
ABSTRACT
PUBLICATION RECORD
- Publication year
2017
- Venue
PLoS ONE
- Publication date
2017-04-27
- Fields of study
Medicine, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- area burned
The burned area within a radius around the depositional environment, treated as a fire-regime component.
Aliases: burned area
- charcoal area
The total area of charcoal particles in a sample, used alongside count as a fire proxy.
Aliases: charcoal particle area
- charcoal count
The number of charcoal pieces recovered from a sediment sample and used as a proxy for past fire activity.
Aliases: number of charcoal pieces, charcoal pieces count
- charcoal particle size cutoff
The sieve-size threshold used to include charcoal particles in grassland sediment analyses.
Aliases: 120 μm mesh, 60 μm cutoff, mesh size
- charcoal shape
The geometric form of charcoal particles, assessed here with the width-to-length ratio.
- grassland vegetation cover
The proportion of grassland vegetation surrounding the site, used to relate charcoal traits to fuel type.
Aliases: vegetation cover
- width-to-length ratio
The width divided by the length of a charcoal particle, used as a shape metric.
Aliases: W:L ratio
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