NOAA/WDS Paleoclimatology - Higuera fire data from Raven Lake, Noatak River Valley, Northwestern Alaska - IMPD USRA-001

Tundra fires have important ecological impacts permafrost, and carbon cycling, but the on vegetation, wildlife, pattern and controls of historic tundra fire regimes are fire and vegetation history poorly understood. We use sediment records from four lakes to in a highly flammable tundra region develop a 2000-yr and compare this history with previously published fire records to examine spatial across Arctic Alaska. The four sites span and temporal variability a modern climatic gradient of tundra burning in the Noatak National Preserve, from warmer, drier down-valley locations. Modern vegetation valley sites, and pollen data past two millennia. Peaks in event return intervals (FRIs), locations to cooler, generally moister up-valley varies from herb- to shrub-dominated tundra from down- to up- suggest that this spatial pattern in macroscopic charcoal accumulation which did not vary significantly vegetation persisted over the provide estimates of fire- at millennial time scales but did vary across space. Down-valley with median FRIs of 150 years (95% sites burned relatively frequently CI 101-150) over the past similar to those from ancient shrub tundra and modern boreal forest. At significantly longer than those at 128-285). These differences evaporative demand at shaped tundra fire two millennia, and FRI distributions statistically up-valley sites FRIs were down-valley sites, with a median FRI of 218 likely reflect the cooler up-valley sites, but local-scale regimes. Comparisons with other that the tundra biome can sustain a wide range years (95% CI growing-season temperatures and lower variability in vegetation may have also long-term fire records in Alaska reveal of burning, with individual FRIs from as low as 30 years to more than 5000 burning has occurred under a years. These records range of climatic and fire histories within Alaska suggests together indicate that vegetation scenarios. The that the ecological impacts frequent tundra variety of tundra of tundra burning likewise vary widely, for wildlife-habitat maintenance and for the responses with important implications of tundra biophysical and biogeochemical processes Key words: Alaska; Arctic; charcoal analysis; climatic to climatic change.