FIRE REGIMES ON ANDESITIC MOUNTAIN TERRAIN IN NORTHEASTERN YELLOWSTONE-NATIONAL-PARK, WYOMING

A fire history investigation was conducted for three forest community types in the Absaroka Mountains of Yellowstone National Park, Wyoming. Master fire chronologies were based on fire-initiated age classes and tree fire scars. The area's major forest type, lodgepole pine (Pinus contorta Dougl. var. latifolia) ecosystems, revealed a predominant pat tern of stand replacing fires with a 200 year mean interval-nearly hal f the length estimated in previous studies of lodgepole pine on less p roductive subalpine plateaus in YNP. High elevation whitebark pine (P. albicaulis Engelm.) forests had primarily stand replacing fires with >350 year mean intervals, but some stands near timberline also occasio nally experienced mixed severity- or non-lethal underburns. Before nea rly a century of effective fire suppression in Yellowstone's northern range, lower elevation Douglas-fir (Pseudotsuga menziesii [Mirb.] Fran co.) communities adjacent to Artemesia tridentata (Nutt.) grasslands e xperienced primarily non-lethal underburns at 30 year mean intervals. While short interval fire regimes have been altered by longterm fire s uppression, fire exclusion apparently had only limited influence on th e area's infrequently burned ecosystems prior to widespread stand repl acement burning in 1988.