Seminar Abstract

Jeremy Littell

Wednesday, February 20, 2005

Ecological context of climate impacts on fire: Wildland fire area burned in the western U.S. 1916-2003

We used two wildland fire area burned datasets and historical climate data to evaluate the degree to which climate variability between 1916 and 2003 exerted an influence on the annual area burned in eco-provinces of 11 western states in the US. One of the fire datasets is 88 yr long and cumulated by state. The second is 21 yr but has greater spatial precision at 1°x 1° lat/long. We used the relationships during the common period to reconstruct area burned by eco-province for the full record. Preliminary work suggests relationships between the two fire area burned datasets are reasonable for reconstruction purposes in most eco-provinces (average R2 = 0.55, range = 0.16 – 0.81) and that the fire/climate relationships are often
temperature- and drought- driven. Sub-regional seasonal and annual predictors for temperature and precipitation combined explain 25-52% (mean 30%) of the variability in 1916-2003 fire area burned. Increasing fire area is positively associated with lagged precipitation for many of the semi-desert steppe and grassland eco-provinces, whereas the relationship is negative for more heavily forested eco-provinces. A simple log-transform
procedure indicates that annual temperature is the single best predictor for 9 of the 15 preliminary eco-province models. However, careful analysis of the distribution of the fire area burned data suggests a more complex procedure is indicated and the climate controls on fire are mixed between precipitation and temperature depending on ecosystem. Our results suggest that the ecological context of twentieth century climate/fire relationships has some similar features with the fire history record prior to the mid-19th century.


Speaker bio:

Jeremy Littell is a CIG-supported PhD student in the University of Washington's College of Forest Resources.