Research links tundra fires, thawing permafrost

November 10, 2015

Wildfires on Arctic tundra can contribute to widespread permafrost thaw much like blazes in forested areas, according to a study published in the most recent issue of the online journal Scientific Reports.

The project, led by the U.S. Geological Survey, examined the effects of the massive Anaktuvuk River fire, which burned roughly 1,000 square kilometers of tundra on Alaska's North Slope in 2007. Using aerial data, researchers detected permafrost thaw in about a third of the fire's footprint, compared to less than 1 percent in undisturbed areas.

"Once you burn off that protective layer, what we observed is the effect isn't immediate but takes a few years to really get going," said Chris Arp, a study co-author and assistant professor at the University of Alaska Fairbanks Water and Environmental Research Center.

The connection between wildfires and permafrost loss is better documented in boreal forests, where burns are relatively common. Tundra fires are less common, so their effects have not been studied as extensively. Using a laser mapping technique called lidar, researchers were able to document thawing during flyovers both two and seven years after the fire occurred.

Researchers flew over the area repeatedly, using lidar to produce detailed topographic models of the burned area. Anchorage-based USGS research geographer Benjamin Jones led the project.

Photo by Christopher Arp. New growth sprouts from tussocks on the tundra following the Anaktuvuk River fire in 2007.

They found that thermokarst, irregular topography such as slumping hillsides and surface depressions, was common in the fire zone.

Arp said lidar was an invaluable resource. The data allowed researchers to measure changes in the land surface over time and predict how these changes will affect hydrology and vegetation within the Anaktuvuk River fire boundary, Arp said.

Understanding conditions that cause permafrost thaw is important because the frozen soils and peatlands store significant amounts of carbon, the Scientific Reports study states. When permafrost thaws, the organic material in the soil decomposes and releases greenhouse gases, such as methane and carbon dioxide, which are considered factors in climate change.

Arp said the changes are also notable because permafrost is the foundation of Arctic lands and ecosystems, both in the wilds and areas where roads and pipelines are built. Dramatic changes in permafrost, like the conditions observed following the Anaktuvuk River fire, will create new plant communities, change wildlife habitat and affect downstream waters, he said.
-end-
Contributors to the study included the USGS Land Change Science and Land Remote Sensing programs, the USGS Alaska Science Center, UAF, the Arctic Landscape Conservation Cooperative, and the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research.

The study is available at Scientific Reports, the online journal from Nature, at http://www.nature.com/articles/srep15865.

University of Alaska Fairbanks

Related Permafrost Articles from Brightsurf:

Coastal permafrost more susceptible to climate change than previously thought
Research led by Micaela Pedrazas, who earned her masters at The University of Texas at Austin Jackson School of Geosciences working with Professor Bayani Cardenas, has found permafrost to be mostly absent throughout the shallow seafloor along a coastal field site in northeastern Alaska.

Arctic Ocean sediments reveal permafrost thawing during past climate warming
Sea floor sediments of the Arctic Ocean can reveal how permafrost responds to climate warming.

Thawing permafrost releases organic compounds into the air
When permafrost thaws due to global warming, not only the greenhouse gases known to all, but also organic compounds are released from the soil.

Siberia's permafrost erosion has been worsening for years
The Arctic is warming faster than any other region on the planet.

Alaska is getting wetter. That's bad news for permafrost and the climate.
Alaska is getting wetter. A new study spells out what that means for the permafrost that underlies about 85% of the state, and the consequences for Earth's global climate.

Plant roots increase carbon emission from permafrost soils
A key uncertainty in climate projections is the amount of carbon emitted by thawing permafrost in the Arctic.

Stocks of vulnerable carbon twice as high where permafrost subsidence is factored in
Twice as much carbon in permafrost is vulnerable to microbial respiration when researchers from Northern Arizona University accounted for subsidence, the gradual sinking of terrain caused by loss of ice and soil mass.

Carbon emission from permafrost soils underestimated by 14%
Picture 500 million cars stacked in rows. That's how much carbon -- about 1,000 petagrams, or one billion metric tons - -is locked away in Arctic permafrost.

Nitrogen in permafrost soils may exert great feedbacks on climate change
A new Sino-German scientific collaboration investigating nitrogen in the soils of China's melting permafrost aims to get to the bottom of why emissions of nitrous oxide -- an often overlooked greenhouse gas -- are greater than they are supposed to be.

Patterns in permafrost soils could help climate change models
A team of scientists spent the past four summers measuring permafrost soils across a 5,000 square-mile swath of Alaska's North Slope.

Read More: Permafrost News and Permafrost Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.