Scientific Journal (JRNL)
The purpose of this paper is to quantify climatic controls on the area burned by fire in different vegetation types in the Western United States. We demonstrate that wildfire area burned (WFAB) in the American West was controlled by climate during the 20th century (1916-2003). Persistent ecosystem-specific correlations between climate and WFAB are grouped by vegetation type (ecoprovinces). Most mountainous ecoprovinces exhibit strong year-of-fire relationships with low precipitation, low Palmer drought severity index (PDSI), and high temperature. Grass- and shrub-dominated ecoprovinces had positive relationships with antecedent precipitation or PDST. For 1977-2003, a few climate variables explain 33 to 87 percent (mean = 64 percent) of WFAB, indicating strong linkages between climate and area burned. For 1916-2003, the relationships are weaker, but climate explained 25 to 57 percent (mean = 39 percent) of the variability. Despite the possible influence of fire suppression, exclusion, and fuel treatment, WFAB is still substantially controlled by climate. The implications for planning and management are that future WFAB and adaptation to climate change will likely depend on ecosystem-specific, seasonal variation in climate. In fuel-limited ecosystems, fuel treatments can probably mitigate fire vulnerability and increase resilience more readily than in climate-limited ecosystems, in which large severe fires under extreme weather conditions will continue to account for most area burned.