PALEOECOLOGY PALEOECOLOGY PALEOECOLOGY Forest fire and climate change in western North America: insights from sediment charcoal records

© The Ecological Society of America www.frontiersinecology.org F fires have swept into public and policy awareness over the past several decades, with an increase in the frequency of large fires in western North America (Westerling et al. 2006). At the same time, human settlements and other infrastructure are impinging on the wildland interface at an unprecedented rate, resulting in annual US federal suppression costs exceeding $1 billion in 3 of the past 6 years (OIG 2006). These recent, large fires have been attributed to a variety of processes, from local increases in fuel loads and shifts in stand composition to regional and global changes in climate (Schoennagel et al. 2004). In some regions, such as the southwestern US, historical fire suppression has been blamed for increases in stand density and fire severity (Allen et al. 2002). In contrast, climate change explains recent patterns in fire occurrence over broad areas of western North America (Fauria and Johnson 2006; Trouet et al. 2006). The few forecasts that exist indicate that the trend toward increased incidence of fires will continue (eg McKenzie et al. 2004; Flannigan et al. 2005). To place modern fire processes in a meaningful context, scientists and policy makers need a long-term view of fire variability. Fossil records describing past ecosystems (paleoecological records) can quantify the historical range of variability of fire occurrence. They can therefore provide an important reference for ecosystem-based strategies aimed at maintaining ecological processes, habitats, and species (eg Willis and Birks 2006; Figure 1). It should be made clear, however, that application of paleoecological data to forecasting the future is complicated by the fact that the future may not resemble any time in the past (Jackson and Williams 2004), particularly with respect to the climatic and fuel controls of fire. While this may limit the potential for the past to serve as an analog for the future, there is an important need for a mechanistic understanding of the processes that proPALEOECOLOGY PALEOECOLOGY PALEOECOLOGY