Reconstruction of fire history

Wildfires are an important parameter in the biosphere-climate system and affect the carbon cycling. Thus, reconstructing their history helps to understand palaeoenvironmental conditions and is essential to project future biosphere-climate interactions and associated carbon cycles.
Wildfire reconstruction has mainly been based on dated lake sediment cores, where the number of microscopically detected charcoal particles has served as the raw data for assessing the past fire frequency. Quantifying (microscopically) visible charcoal may reflect the relatively large and structurally sound charcoal particles from forest fires. However, this technique is less likely to quantify smaller charcoal fractions derived from grasses – probably the main contributor of charcoal in savannas and open grassy woodlands.
Therefore, we are developing a new methodology to infer past wildfires from lacustrine sediments by using molecular marker methods. Such molecular markers could assess the whole size range of charred fire residues in sedimentary records and could yield additional information about the burned vegetation when only microscopically invisible fire residues are present.
In order to calibrate and validate the molecular marker methods for sedimentological fire reconstruction, we use well characterized lake sediment cores from Australia. They exhibit distinct wildfire histories (charcoal counting method) – data, that can be compared to the results of molecular marker analyses.