Fire in the Arctic Tundra: How Alaska's Tussock Grasslands Burn and Recover

Tussock cottongrass flowering in Noatak National Preserve a year after a fire. NPS photo by J. Barnes.

The tundra

Arctic tundra covers the far north and far west of Alaska, where forests don't grow well. Walking on it can feel like crossing a sponge studded with big grassy "bowling balls" — tussocks. Tussock-forming sedges, such as cottongrass and Bigelow's sedge, grow among low shrubs like willow and dwarf birch. Mosses and lichens carpet the ground and build a deep mat of decaying plant matter — duff — that shields the soil and the permafrost beneath.

Fires in Alaska's arctic and subarctic tundra, 1940 to 2020. NPS map by J. Hrobak.

How fire behaves here

• Less often than in the boreal forest: tundra fires are sporadic and scattered. The time between fires — the fire return interval — ranges from 30 years to more than 1,000.
• More often on the Seward Peninsula and in the Noatak Valley, which are slightly warmer and drier and carry more plant growth above ground, such as tussock cottongrass.
• Fast and wind-driven: tussock cottongrass (Eriophorum vaginatum) builds its tussock from fine dead leaves of past years, which burn quickly and easily, so fires race through years of built-up thatch.
• Hardy: the tussock itself protects the plant's roots and growing tissue, so cottongrass and shrubs resprout fast and grow vigorously after fire, helped by released nutrients and warmer soil.

A vegetation plot one month after a 1982 fire: tussocks resprout very quickly. NPS photo by C. Racine.

The same plot in 2013, a year after it burned again in 2012 — the tussocks are larger and greener. Fire can stimulate tussock growth. NPS photo by J. Barnes.

Today and tomorrow

Alaska has more than 143 million acres of arctic and subarctic tundra, most of it managed under a Limited Fire Management Option, where fires play their natural role. How many fires start depends on ignitions such as lightning, moisture, and how much fuel there is.

Over the past twenty years, scientists have seen warmer temperatures and more fire in tundra where fire used to be uncommon. Climate models forecast more warming, especially in the far north, which could change the growing season, plant growth, and rain and snow — and scientists expect more fires. How that will reshape the tundra is still unknown. Park scientists track vegetation and fire over time, and fire managers use what they learn to protect resources and keep ecosystems in balance.

More: the last 6,000 years of fire in Noatak National Preserve and long-term vegetation monitoring after tundra fires. The parks include Bering Land Bridge, Cape Krusenstern, Gates of the Arctic, Kobuk Valley and Noatak.

Sources

Based on "Fire in Ecosystems: Arctic Tundra," National Park Service; a work of the United States government in the public domain. The source's "Bigleow's sedge" is corrected to Bigelow's sedge.