UNDERSTANDING THE ORIGIN OF SEDIMENT-CHARCOAL RECORDS WITH A SIMULATION MODEL

HIGUERA, P.E. (1), PETERS, M.E., (2), GAVIN D.G. (3).

(1) College of Forest Resources, University of Washington, (2) Department of Applied Mathematics, University of Washington, (3) Department of Plant Biology, University of Illinois.

Understanding the processes linking fires on a landscape to the creation of sediment-charcoal records is critical for evaluating the accuracy of paleofire reconstructions. To this end, we developed the Charcoal Simulation Model (CharSiM), a numerical model that simulates macroscopic charcoal records based on fire frequency, size, and location, and on parameters for charcoal dispersal, primary and secondary charcoal deposition, sediment mixing, and sediment sampling. We use CharSiM to (1) develop a quantitative understanding of the impacts that natural variability in fire regimes, charcoal dispersal and charcoal deposition have on sediment-charcoal stratigraphy, and (2) understand how analytical choices impact the accuracy of fire history interpretations. Variations in fire size and fire location contribute the most variation to simulated charcoal records. When analyzing simulated records using standard methods, reconstructing fire occurrence for a single spatial domain with perfect accuracy is rarely possible. The combination of variations in fire characteristics and charcoal dispersal causes some fires to go undetected, while others from beyond a given spatial domain leave distinct charcoal peaks. These errors are most important for the interpretation of individual fires. When quantifying fire history in terms of fire-frequency regimes, simulated and reconstructed fire histories are rarely inconsistent.