Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Boreal forest fires could release deep soil carbon

22.08.2019

Increasingly frequent and severe forest fires could burn generations-old carbon stored in the soils of boreal forests, according to results from the Arctic-Boreal Vulnerability Experiment (ABoVE) funded by NASA's Earth Science Division. Releasing this previously buried carbon into the atmosphere could change these forests' balance of carbon gain and loss, potentially accelerating warming.

Canada's Northwest Territories were scorched by record-breaking wildfires in 2014. The team of researchers from the United States and Canada took soil samples from more than 200 locations in the region.


The research team sampled more than 200 plots in the forests of Canada's Northwest Territories to see whether "legacy" carbon left over from previous fire cycles was threatened by the intense 2014 fires. They found that forests less than 60 years old and located in drier climates had a higher risk of losing legacy carbon in the fires than older, wetter forests.

Credits: NASA / Xanthe Walker, Center for Ecosystem Science and Society at Northern Arizona University

They found that for old forests (more than 70 years old) and forests in wet locations, a thick layer of organic matter in the soil protected the oldest carbon, called "legacy carbon," that was not burned in previous cycles of burn and regrowth. However, in younger, drier forests, the shallower soil organic matter layer allowed fires to reach the legacy carbon, releasing it into the atmosphere.

As Earth's northern regions grow warmer and drier due to climate change, fire seasons are getting longer and fires are becoming more severe. Boreal forests have long been thought to absorb more carbon from the atmosphere than they release into it, making them carbon "sinks."

But if bigger and more frequent fires start burning legacy carbon, these forests could start releasing more carbon than they store. Carbon dioxide is a greenhouse gas, so releasing more of it into the atmosphere could affect the balance of the global carbon cycle and contribute to climate change

Boreal forests are located in the northernmost regions of North America, Europe and Canada, and contain spruce, fir, pine, larch, aspen and birch trees. These forests store 30%-40% of all land-based carbon in the world, and most of that carbon is found in the soils. Soil-based carbon includes soil microbes; plant material made up of dead leaves, branches and stems; and both living and dead roots, as well as burned material from previous fires.

During intense fires, the organic material that contains the soil carbon can burn along with trees and plants. Older carbon deeper in the soil does not always burn in a fire, but can stay protected in the soil. The researchers called this "legacy carbon."

After observing the intensity of the 2014 fires, the team wondered if these pools of legacy carbon were at risk.

"Carbon accumulates in these soils like tree rings, with the newest carbon at the surface and the oldest carbon at the bottom," said senior author Michelle Mack, a professor at Northern Arizona University's Center for Ecosystem Science and Society. "We thought we could use this layering to see how far back in time, in the history of the forest, fires were burning."

The team measured the age of the trees, how deep in the soil the fire burned, how moist the sampled area was, and the depth of the topmost soil organic layer, composed of plant and animal matter. They also used radiocarbon dating of the soils to determine if the legacy carbon pools burned in the fire.

The team found that wetter forests and those less than 60 years old were more likely to contain legacy carbon than older, drier forests. But the ones most likely to lose that legacy carbon were the young forests in drier areas. These forests were less likely to have accumulated enough organic matter to protect the older carbon between previous fires and the 2014 fire. Almost half of the plots under 60 years old lost legacy carbon, while just one older plot did.

In total, about 12% of the forests that burned in the 2014 fires met the criteria for being vulnerable to legacy carbon loss. The researchers estimate that these forests released about 8.8 million tons of carbon as they burned, compared to the nearly 104 million tons released by all the fires.

The team said their results show that in order to understand the effects of future fires on Canada's boreal forests and the global carbon cycle, researchers must account for legacy carbon loss.

"By defining and analyzing 'legacy carbon,' this paper offers a new way to think about long-sequestered carbon stocks in boreal forests and how vulnerable they are to being burned during increasingly frequent and severe wildfires," said Brendan Rogers, a scientist at Woods Hole Research Center who co-authored the Nature study. "This tool helps us understand when burning goes 'outside the norm' from a historical perspective and begins to combust carbon stocks that survived past fires."

If wildfires do become more frequent, they could increase the number of young forests vulnerable to burning and legacy carbon loss, they added.

"In older stands that burn, legacy carbon is protected by thick organic soils," said Xanthe Walker, lead author and postdoctoral researcher at the Center for Ecosystem Science and Society at Northern Arizona University. "But in younger stands that burn, the soil does not have time to re-accumulate after the previous fire, making legacy carbon vulnerable to burning. This pattern could shift boreal forests into a new domain of carbon cycling, where they become a carbon source instead of a sink."

###

NASA's ABoVE campaign supports research using remote sensing, airborne measurements and field investigations to understand climate change's impacts on Alaska and northern Canada. The Arctic is changing faster than anywhere else on Earth, and ABoVE studies track shifting coastlines, changing plant growth patterns and greenhouse gas emissions from thawing permafrost and boreal forest fires.

To learn more about the Arctic Boreal Vulnerability Experiment, visit https://above.nasa.gov/.

Banner Image: The 2014 fires in Canada's Northwest Territories burned more than 7 million acres of boreal forest, mainly comprised of cone-bearing trees like these jack pines. The fires released nearly 104 million tons of carbon into the atmosphere. Credit: NASA / Xanthe Walker, Center for Ecosystem Science and Society at Northern Arizona University.

By: Jessica Merzdorf

NASA's Goddard Space Flight Center, Greenbelt, Maryland

Jessica Merzdorf | EurekAlert!
Further information:
https://www.nasa.gov/feature/goddard/2019/boreal-forest-fires-could-release-deep-soil-carbon

More articles from Earth Sciences:

nachricht Shrinking of Greenland's glaciers began accelerating in 2000, research finds
11.12.2019 | Ohio State University

nachricht One-third of recent global methane increase comes from tropical Africa
11.12.2019 | European Geosciences Union

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

Im Focus: Electronic map reveals 'rules of the road' in superconductor

Band structure map exposes iron selenide's enigmatic electronic signature

Using a clever technique that causes unruly crystals of iron selenide to snap into alignment, Rice University physicists have drawn a detailed map that reveals...

Im Focus: Developing a digital twin

University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making

In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Self-driving microrobots

11.12.2019 | Materials Sciences

Innovation boost for “learning factory”: European research project “SemI40” generates path-breaking findings

11.12.2019 | Information Technology

Molecular milk mayonnaise: How mouthfeel and microscopic properties are related in mayonnaise

11.12.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>