Understanding the historical range of variability in wildfire helps managers understand the degree to which different forest types are departed from historical conditions and potentially less resilient to future climate and disturbance. Information about historical fire disturbance also helps prioritize and plan forest restoration treatments. Researchers have created extensive tree-ring based fire histories throughout seasonally dry forests of the western United States. But until recently, no comparable fire histories exist for the most productive Douglas-fir dominated forests in the western Oregon Cascades.
In this study, researchers used tree-ring evidence to reconstruct historical fire occurrence and tree establishment at 36 randomly located sites throughout the Willamette and Mt. Hood National Forests in northwestern Oregon. At each ~5-acre site, researchers removed cross sections from 15-20 stumps and cross-dated both fire scars embedded in tree rings and the pith of the tree that indicates the year of tree establishment. These records provide important new information about the nature of wildfire in highly productive, Douglas-fir dominated forests that are a critical part of the economic and cultural life of the region.