Arctic Vegetation Archive - Alaska: Tundra Fires.
The vegetation associated with tundra fire scars on the Seward Peninsula and northern foothills of the Brooks Range in Arctic Alaska was surveyed in the field during late June and July 2011 and 2012. This research was supported by USGS Alaska Science Center grants to Amy Breen and Teresa Hollingsworth (Seward Peninsula) and Benjamin Jones (North Slope).
The surveys focused on upland tundra settings and provide information on vegetative differences between burned and unburned sites. Unburned sites were selected that were moist tussock tundra dominated by tussock cottongrass, Eriophorum vaginatum, which is the most commonly burned vegetation community in Arctic Alaska. The burned sites were selected in areas of similar elevation and topography that were inferred to be moist tussock tundra pre-fire based on the presence and abundance of live or dead E. vaginatum tussocks. The tussocks, especially in the younger fire scars, showed evidence of charring at their base.
Our aim in this sampling design was to establish a chronosequence of sites that vary in time since last fire to better understand post-fire vegetation successional trajectories. While we cannot be certain plant communities followed the same post-fire successional pathway in this space-for-time substitution, we use the chronosequence approach as an exploratory method given there are few direct repeat post-fire observations in Arctic Alaska. Assessment of vegetation succession along the century-scale chronosequence of tundra fire disturbances demonstrated for the first time on the North Slope of Alaska that tundra fires can facilitate the invasion of tundra by shrubs.
On the Seward Peninsula, plots were 1 x 1 m in areas of homogenous vegetation, and complete species lists and their cover abundance were recorded. On the North Slope, plant species and height were recorded every 1 m along 30 m transects. All taxa that touched the sampling pin were recorded as “hits.” Species adjacent to the transect, but not encountered, were also recorded. Percent cover was calculated by dividing the number of hits for each taxa by the total number of points along each transect. The taxa that were not encountered along the transect were given a rare cover abundance so that these plots also have complete species lists. Sixty-four tundra fire and unburned plots from the Seward Peninsula (43 plots) and North Slope (21 plots) were surveyed. All but two plots occur in the habitat type, “Moist to wet acidic tussock and nontussock (Eriophorum vaginatum-Carex bigelowii-Sphagnum-Hylocomium) tundra.” The other two plots most closely resemble the “Moist nonacidic tundra (Sedge-Dryas-Tomentypnum communities)” habitat type, although there is evidence (dead tussocks) these plots were dominated by tussock tundra pre-fire.
Original data from the northern foothills of the Brooks Range were published as part of a study of vegetation and permafrost-terrain characteristics that identified two large previously unrecognized tundra fires (Jones et al. 2013). Breen (2015) summarized her results from the Seward Peninsula and presented them at the American Geophysical Union’s annual fall meeting and is currently preparing both datasets for publication in the journal Phytocoenologia.
References
Breen, A. L., T. Hollingsworth, M. Mack, B. Jones. Succession Stages of Tundra Plant Communities Following Wildfire Disturbance in Arctic Alaska. Abstract # B31C-0567. 2015 Fall Meeting, American Geophysical Union. San Francisco, California. December 2015.
Jones, B. M., A. L. Breen, B. V. Gaglioti, D. H. Mann, A. V. Rocha, G. Grosse, C. D. Arp & D. A. Walker. 2013. Identification of unrecognized tundra fire events on the North Slope of Alaska. Journal of Geophysical Research 118: doi:10.1002/jgrg.20113
