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Fire history in the Yukon Flats National Wildlife Refuge, Alaska.
Drury, Stacy1, 1
ABSTRACT- Fire is a very important environmental factor in the forests of interior Alaska. Wildfires in these forest types are commonly characterized by large fires that kill most of the aboveground vegetation. From 1939 until 1984 all wildfires were actively suppressed on the Yukon Flats National Wildlife Refuge (YFNWR). Since 1984 one of the refuges fire management goals is to allow naturally ignited wildfires to burn under a wide range of conditions to maintain the natural diversity of wildlife habitat. However, little information exists concerning the historic variablility of the fire regime within the YFNWR. I was interested in answering questions concerning the historic intervals between fires, the mean stand ages when burned, and what types of plants colonizied the post-fire areas. To answer these questions I sampled 23 sites within the YFNWR. At each site, past fires were dated using cross-sections from fire scarred trees, cohort ages from cohorts initiated by the last fire, and the death dates of fire-killed trees. Mean stand ages for burned areas were determined solely from cohort ages of stands killed by past fires. Fire intervals were determined when the dates of both the fire that initiated the stand and the fire that killed the stand were known. The intervals between fires ranged from 38 to 91 years (mean = 62 years) depending on terrain and pre-fire vegetation type. Post-fire regeneration of white spruce (Picea glauca), black spruce (Picea mariana), and aspen (Populus tremuloides) was within 10 years or less of the most recent fire. Stand ages when burned varied from 35 to 110 years old (mean = 67 years, SD = 17 years). The information reported here will provide land managers with a baseline for managing wildfires within a range of the historic variablity of fire occurrence in interior Alaska.
KEY WORDS: Fire Regime, Alaska