Patterns of Vegetation Recovery after Tundra Fires in Northwestern Alaska, U.S.A.

Abstract

Studies of lightning-caused tundra fires were carried out between 1977 and 1983 in three areas of northwestern Alaska (Seward Peninsula [65°35'N], Noatak River [68°00'N], and Kokolik River [69°30'N]) representing a latitudinal gradient of 460 km. Postfire vegetation and permafrost recovery rates were documented in both tussock and low-shrub tundra ecosystems burned up to 10 yr prior to sampling.

Within 5 to 6 yr following 1977 tundra fires, total vascular plant cover reached 50 to 100% of the unburned control at all sites with the slowest recovery at the northernmost Kokolik River site. This difference may be accounted for by the greater severity of burning at the Kokolik River sites where the fire occurred late in the season (1 August) and where there is a longer interval between fires. Postfire increases in soil thaw in tussock tundra appeared to stabilize or return to prefire levels within the same 5- to 6-yr time span.

Many tundra plants appear to be well adapted to fire through one or a combination of strategies described. Eriophorum vaginatum tussocks may be dependent on fire for removal of competing low shrubs and mosses. Seed and seedling fluxes of certain species increase dramatically following fire. A model is presented which relates species fire survival strategies to the severity of burning and the seasonal timing of fire.