NOAA/WDS Paleoclimatology - Heyerdahl fire data from Lytle Creek, central Oregon - IMPD USLYT001

Dry mixed-conifer forests are widespread in the interior west of North America, but their historical fire regimes are poorly understood. We reconstructed a multicentury history of the spatial complexity in forest fire regimes (frequency, severity, and extent) in dry mixed-conifer forests in central Oregon. We sampled four 30-plot grids over 3,222 ha, one in the eastern Cascade Range and three in the Ochoco Mountains. All four sites are currently dominated by grand fir, Douglas-fir, and ponderosa pine with varying, but minor, amounts of western larch, incense cedar, or western juniper growing fine-grained mosaics. We sampled 4,065 trees to determine their recruitment dates and/or the dates of surface fires and used these to reconstruct remarkably similar historical fire regimes at all four sites. These regimes were dominated by frequent and often extensive surface fires, but included occasional patches of severe fire. Although forest types varied within sites, historical fire regimes did not vary substantially among these types.