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Climate, fire, and demography central Oregon 1560-1900 AD
Presented by Dr. Donald FALK on 15 May 2013 from 18:00 to 21:00
Type: Poster Presentation
Session: Poster Session + Reception
Board #: 14
Documenting historical fire regimes provides an unparalleled view of ecosystem function across spatiotemporal scales. We analyzed fire-scars and tree demography in a multiscale dendrochronological study from a network of sites in central and eastern Oregon. We sampled over 6000 trees for tree-establishment dates in ponderosa pine, dry and mesic mixed conifer, and lodgepole-ponderosa pine communities. Fire history was based on 12 new collections and 7 existing records. Fire-scar chronologies indicate 22 years in the period 1560-1900 with more than 10 sites recording fire, representing regionally widespread fire years on average every 16 years. Demography analysis revealed complex patterns of mixed-severity fire as expressed in tree regeneration patterns. Regional fire years occurred primarily in years of negative PDSI and above-average spring-summer temperature, whereas local and non-fire years were not different from mean conditions for the period of record, indicating a contingent relationship of seasonal climate to the extent of regional fire years.