Burning Questions

May 17, 2010

Scientists Seek Information from the Anaktuvuk River Fire

By Emily Stone

Journalists visited the site of the Anaktuvuk River Fire last summer. The charred tussocks were still visible beneath the blooming cottongrass. Photo: Lisa Jarvis

Gaius Shaver has been traveling to Toolik Field Station for 34 summers to study how tundra ecosystems react to small environmental changes. One of his experiments involves building greenhouses over 8-by-16 foot plots of land to gauge how plants react to warmer soil.

His research has yielded interesting results over the years, but there’s always been a question of how well that data would translate over large tracks of land.

Suddenly, Mother Nature gave Shaver and many other Toolik scientists a way to find out.

A massive fire burned about 400 square miles of tundra along the Anaktuvuk River from July to October 2007. It was the largest tundra fire ever recorded on Alaska’s North Slope. Now the scientists are studying how the area, which is roughly the size of Cape Cod, responds. In addition to examining the warming soil and plant changes, the group is looking at how much carbon was lost in the fire, the ongoing exchange of carbon between the land and air, and how melting permafrost is affecting rivers and streams. They’re finding that the fire has had a significant impact in all these areas. And given that continued warming in the Arctic will likely lead to more lightning which will lead to more fires, these are important questions to answer.

The 2007 Anaktuvuk River Fire burned a Cape Cod-sized section of the North Slope. Scientists are interested in how long it will take the area's plants and soil to recover. Photo: Adrian Rocha

“There’s a lot going on,” said Shaver, a senior scientist at the Marine Biological Laboratory who is leading the National Science Foundation-funded, three-year study that includes nine senior collaborators and a couple dozen other researchers. “It’s very exciting.”

The group calculated that the fire burned more than two million tons of carbon that had been stored in the soil, or roughly 25 years worth. This equals about 10 percent of the annual carbon emissions for the city of Boston. The fire also burned between 300 and 1,000 years worth of nitrogen.

The group is also interested in the continued changes in carbon exchange between the soil and atmosphere. Using instruments set up on three towers in the burn site, they’re measuring the exchange of carbon during the summers. If plants photosynthesize more than they and the soils in which they grow respire, then the net result is carbon being removed from the atmosphere. If there’s more respiration than photosynthesis, then the opposite is true.

Overall, the burned areas have a net carbon loss from the soil, meaning more carbon is being released into the atmosphere than at unburned spots. The researchers calculated that in 2008, the fire accounted for a minimum 2.8 percent reduction in the amount of carbon being taken out of the atmosphere across the North Slope even though the Anaktuvuk River Burn accounts for only 0.55 percent of the North Slope’s area.

The researchers know from older fires and erosion scars that shrubs tend to dominate the landscape after a disturbance at the expense of mounds of tussock grasses, which cover much of the North Slope. This seems to be playing out at the Anaktuvuk River Burn. Although shrubs were knocked back dramatically by the fire — even more than the tussocks — they are recovering rapidly even in severely burned areas and may soon exceed the grasses in the amount of ground they cover. 

Undisturbed tundra tends to keep its plants in pretty consistent ratios as they compete for limited resources in the soil. “A disturbance shakes up those relationships among species,” Shaver said. This is important because shrubs tend to insulate the soil in the winter, keeping it warmer, and also hold less carbon below ground than tussocks do, both of which can further change the landscape.

Another striking discovery is the change in albedo, meaning the percent of the sun’s radiation that is reflected away from the ground. In the first summer after the fire unburned portions of the burn site had a 17 percent albedo while severely burned sections had a 3.5 to 4 percent albedo. That means an additional 13 percent of the sun’s radiation was being absorbed in those areas. And that heat has to go somewhere, often warming the soil to higher temperatures and permeating deeper than normal. This difference was less in 2009 than in 2008, and Shaver said it will eventually return to the level of unburned tundra. 

Data show that burn scars absorb more of the sun's radiation than unburned tundra, increasing soil temperatures. Photo: Adrian Rocha

In the meantime, increased heat flux into the ground can cause thermokarst failures, which occur when the ice that’s normally frozen solid in permafrost melts and the land above it collapses like a soufflé. Last summer the group noticed more and more of these depressions as the season continued. When thermokarst erosion happens near streams and lakes, it dumps extra nutrients into the water, giving microbes, plants and fish access to more food and thus changing the aquatic ecosystems. 

“We can’t make a treaty to stop thermokarst and fires,” said Syndonia Bret-Harte, an associate professor at the University of Alaska Fairbanks, who is heading up the plant studies at the burn.

Bret-Harte, who is also Toolik’s associate science director, was at the station in 2007 while the fire was burning about 25 miles away and at times could see a wall of smoke in the distance.

“It was awesome and beautiful, but disturbing at the same time,” she said.

Once the scientists realized how big the fire was, Shaver applied for an NSF grant for the following summer, knowing how valuable the natural experiment would be for the scientists at Toolik, many of whom are part of an ongoing Long Term Ecological Research Project, one of 26 in the U.S. LTER network.

The group is adding a component to this summer’s research by visiting the sites of two large fires from 1993 to see how they’re recovering in hopes of predicting how the Anaktuvuk River Burn will fare in the coming years. They’ll take measurements to see, for example, how much soil has accumulated above the char level and what the diversity of plant species is like.

All of this is crucial information to have as more and more disturbances like lightning-driven fires and thermokarst occur across the Arctic.

“Overall climate change is gradual and the overall response to this change is gradual,” Shaver said. “But then we have these patches of intense change and the patches may be changing so intensely that from the perspective of the whole North Slope, they actually dominate the overall changes.”


In the Media

October 7, 2009

Spotlight on Toolik Field Station Research

Toolik Field Station

Toolik Field Station

Science journalist Leslie Dodson has released some videos recorded at Toolik in 2008 for the Video Journalism Movement. The VJ Movement facilitates collaborations between a global network of freelance video journalists, editorial cartoonists and the public. Participating in the Wood’s Hole Marine Biological Lab Science Journalism Fellowship, Dodson trailed Toolik LTER scientists and others two summers ago to get the footage.  The following short Dodson videos featuring CPS-supported scientists are an engaging watch.

Searching for Plankton in Toolik: http://vjmovement.com/truth/66

The 2007 Anaktuvak Fire: http://vjmovement.com/truth/185


All in the Family

September 25, 2009

A Toolik scientist brings her children to the field

By Emily Stone 

Sally MacIntyre and her son, Johnny Melack, on Toolik Lake in 2003 when Johnny came to help his mom with her research.

Sally MacIntyre and her son, Johnny Melack, on Toolik Lake in 2003 when Johnny came to help his mom with her research. Photos courtesy Sally MacIntyre

Sally MacIntyre’s research studying the physics and biology of lakes has taken her to some amazing research sites, including Toolik Field Station. But over the years it also meant leaving home — and her two children — for up to a month at a time.

“That’s one of the challenges of being a mom,” she said. “You don’t really ever want to be away from your kids.”

In the back of her mind on these trips, she always thought that it would be great if she could bring her kids with her. She eventually did just that. Her 20-year-old daughter, Megan Melack, spent 10 days this summer working with her at Toolik, just as her son, Johnny Melack, did as an 18-year-old in 2003.

Megan Melack spent 10 days at Toolik Field Station this summer helping her mother, Sally MacIntyre, deploy instruments that measure temperature and turbulence in Toolik Lake below the surface.

Megan Melack spent 10 days at Toolik Field Station this summer helping her mother, Sally MacIntyre, deploy instruments that measure temperature and turbulence in Toolik Lake below the surface.

MacIntyre, a professor at the University of California, Santa Barbara, said it was important that she wait until her children were old enough to appreciate Toolik, both the stunning physical beauty of the place and the community of smart, engaged scientists. She wanted Megan and Johnny to have a social life independent from her, “so it becomes their place too, not just that they’re hanging out with mom.”

The strategy clearly worked.

“I can’t even explain how happy I am that I went there,” said Megan, who is a junior at the University of California, Santa Cruz. “I tell people that my soul was revived.”

Megan had been skeptical of the trip, which her mom had been urging her to make for a few years. She worried that as a self-described “girly” Californian, the giant mosquitoes and primitive living arrangements — outhouses and limited showers — wouldn’t suit her. But she quickly learned to deflect the mosquitoes and got used to the camp’s amenities, or lack thereof, and turned her attention to the people and science around her.

The highlight of the trip was a midnight hike with a small group the night before she left. “I can’t imagine doing that anywhere else in the world with such awesome people,” she said.

The science became real to her, too.

“There’s no way you ever truly understand scientific research unless you go out and do it,” she said. And she suddenly understood what her mom had been doing all those years when she headed off into the field.

Megan Melack helps her mother, Sally MacIntyre, deploy instruments in Toolik Lake that read the temperature and turbulence of the water below the surface.

Megan Melack helps her mother, Sally MacIntyre, deploy instruments in Toolik Lake that read the temperature and turbulence of the water below the surface.

“It made me very proud to see all the things she does out there,” Megan said.

MacIntyre studies the turbulence below the surface of Toolik Lake. Arctic lakes are much more turbulent than similarly sized and, in some cases, much larger temperate lakes. That means that more nutrients are mixed from the bottom into the water column above where there is light to support the growth of tiny phytoplankton. The mixing rates are so high because the difference in water temperature from the top of the lake to the bottom isn’t that great. But if the climate were to warm significantly, that difference would increase and it could cut off the underwater churning. Megan and Johnny helped their mom deploy instruments that read the lake’s temperature and turbulence from the top to the bottom as part of MacIntyre’s ongoing research.

Johnny, who was about to start school at the University of California, Davis, the summer he was at Toolik, had always been interested in science. He now works as a mechanical engineer for a company making hydrogen fuel cells in Davis. During a summer break in college he spent part of his time working with the company that builds MacIntyre’s instruments, and he helped build one of hers. He inscribed “To Mom from Johnny” on it.

“It’s totally wonderful,” MacIntyre said. 

Sally MacIntyre studies the turbulence below the surface of Toolik Lake. She's been able to bring both her children to the camp as young adults to help her with her research.

Sally MacIntyre studies the turbulence below the surface of Toolik Lake. She's been able to bring both her children to the camp as young adults to help her with her research.

Megan, who is majoring in psychology, had been thinking about studying a hard science as well, and said her time at Toolik convinced her that she should. She’s planning to add either an environmental studies or biology minor and is thinking about science journalism or environmental policy lobbying as a career. She’d also like to figure out a way to go back to Toolik, perhaps with a project of her own someday.

They worked hard while at Toolik, so it’s no surprise that Johnny and Megan both enjoyed their time off, too.

Johnny spent much of his free time filming a documentary video about the place, hiking, and playing soccer and basketball under the midnight sun. Megan was an ebullient presence at the camp, chatting easily with people at meals and social activities. She and MacIntyre were both enthusiastic participants in the station’s re-enactment of Michael Jackson’s “Thriller” dance shortly after his death.

MacIntyre said she was grateful for the warmth both old-timers and newcomers at the camp showed Johnny and Megan.

“The fact that people at Toolik reached out to my children made their experiences so positive,” she said.

MacIntyre’s research at Toolik is part of the Arctic LTER program, which is funded by the National Science Foundation.

Emily Stone is a freelance writer. She spent a week at Toolik Field Station last summer as an MBL journalism fellow.