Upgrading Satellite Mapping of Burn Severity

As discussed in the Feb. 7 Fire Science Highlight, burn severity in Alaska is best related to the amount of consumption of the forest floor—not the degree of tree canopy mortality as is in temperate pine and fir forest.  Yet the most commonly applied metric to map burn severity using satellite remote sensing does not correlate well with substrate burn severity.  The change in Normalized Burn Ratio (dNBR; Key and Benson 2003) is based on comparing a pre- and a post-fire image. However, NBR thresholds for severity differ from one fire to another and among different years: similar numbers don’t indicate the same severity levels (D. Chen et al. 2020).  And with tundra fires, sometimes it works, other times not.  This problem has dogged fire effects and ecology studies in Alaska for some time (see list of papers in Sean Parks November 2019 presentation) leading French et al. (2008) to conclude: “Satellite remote sensing of post-fire effects alone without proper field calibration should be avoided.”

ARF63_0-50m_2008

2008 Transect photo from Anaktuvuk River tundra fire (R. Jandt)

Recently, we’ve seen some promising new methods used to improve satellite remote sensing of burn severity in boreal forest.  Whitman et al. compared several indices including a relativized index that facilitated comparisons between different fires in Canada.  She told us about it at the Opportunities to Apply Remote Sensing in Boreal/Arctic Wildfire Management and Science Workshop in 2017—here’s her presentation if you missed it: Improving Remotely Sensed Multispectral Estimations of Burn Severity in Western Boreal Forests.  Loboda et al. ( 2020) found single images using just NIR (near-infrared) bands of Landsat did better than NBR in discriminating tundra fire severity.  Sean Parks is attempting to harness the power of Google Earth Engines and cloud-based computing to use multiple images to further define the ecological burn severity (Parks et al. 2019)—this work is kicking off at the University of Montana.  He also found that unusual aspects of some fires in Alaska (pre-existing beetle kill, short fire return interval) contribute to poor performance of the standard index (see his recorded November, 2019, Association of Fire Ecology meeting presentation HERE).  And Yaping Chen, from the University of Illinois, explored using indices based on Visible and NIR bands (which have a large archive of available imagery going back to the early 1970’s) to evaluate tundra fire severity.  Her paper (Y. Chen et al. 2020) points to a VNIR index called GEMI as a “robust surrogate to NBR in Arctic tundra ecosystems, capable of accurately estimating fire severity across fire seasons, tundra fires, ecoregions, and vegetation types.”  The fact that GEMI is not as influenced by different vegetation types as dNBR gives it a distinct advantage mapping tundra burn severity.

Being able to more accurately map burn severity levels from space would give ecologists a boost for understanding why fires sometimes induce radical changes in ecosystems while other times the system self-replaces in a very short span.  For example, Yaping Chen used GEMI to reconstruct burn severity on older tundra fires like the 1977 example below and tie it to thermokarst effects (like catastrophic lake drainage or ponding) resulting from the fires (poster presented at AGU meeting December 2019).  We look forward to more exciting products and tools coming from these research teams!

Y. Chen et al. 2020, Fig. 7

Reconstructed fire severity map of the 1977 OTZNNW 38 tundra fire computed with dGEMI using Landsat MSS imagery.

Citations:

Chen, Yaping; Lara, Mark J.; Hu, Feng Sheng. 2020. A robust visible near-infrared index for fire severity mapping in Arctic tundra ecosystems. ISPRS Journal of Photogrammetry and Remote Sensing 159:101-113.

Chen, Dong; Loboda, TV.; Hall, JV. 2020. A systematic evaluation of influence of image selection process on remote sensing-based burn severity indices in North American boreal forest and tundra ecosystems. ISPRS Journal of Photogrammetry and Remote Sensing 159:63-77.

French, NHF.; Kasischke, ES.; Hall, RJ.; Murphy, KA.; Verbyla, DL.; Hoy, EE.; Allen, JL. 2008. Using Landsat data to assess fire and burn severity in the North American boreal forest region: an overview and summary of results. International Journal of Wildland Fire 17(4): 443-462.

Key, Carl H.; Benson, NC. 2003. The normalized burn ratio (NBR): A Landsat TM radiometric measure of burn severity. US Geological Survey Northern Rocky Mountain Science Center.

Loboda, Tatiana V.; Hoy, EE.; Giglio, L; Kasischke, ES. 2011. Mapping burned area in Alaska using MODIS data: a data limitations-driven modification to the regional burned area algorithm. International Journal of Wildland Fire 20(4):487-496.

Parks, SA.; Holsinger, LM.; Koontz, MJ.; Collins, L; Whitman, E; Parisien, MA; Loehman, RA.; Barnes, JL.; Bourdon, JF; Boucher, J; Boucher, Y; Caprio, AC.; Collingwood, A; Hall, RJ.; Park, J; Saperstein, LB.; Smetanka, C; Smith, RJ.; Soverel, NO. 2019. Giving ecological meaning to satellite-derived fire severity metrics across North American forests. Remote Sensing 11(14):1735.

Whitman, E, MA Parisien, DK Thompson, RJ Hall, RS Skakun, and MD Flannigan. 2018. Variability and drivers of burn severity in the northwestern Canadian boreal forest. Ecosphere 9(2):e02128. 10.1002/ecs2.2128

Fire, Lichens & Caribou: What Do We Know?

Caribou herds in North America seem to be declining.  Is warming climate or it’s effects on habitat to blame? The relationship of caribou to lichen-rich winter ranges and fire is oftenThumbnailRB2018-1 oversimplified.  Many factors besides habitat affect caribou numbers, which undergo large fluctuations naturally.  In this new Research Brief, we highlight recent publications on caribou-fire relationships and explore some of the factors that make it complicated to predict exactly what will happen and when if old-growth caribou habitats diminish with warming climate and more frequent burning.

 

 

 

 

 

Adam Young consults the crystal ball on future fire regime across Alaska

A paper just published by the indefatigable Adam Young, a PhD candidate at the University of Idaho, and colleagues pulls together a lot of information about climate, forest, tundra and fire to offer a glimpse of potential future fire regimes in different parts of Alaska.  By looking at fire occurrence at a multi-decadal time scale, the researchers drill down into how fire rotations are likely to respond to climate projections at a regional scale.

Young Fig 6 exerpt

Exerpt from Fig. 6, Young et al. 2016. Figures in the paper not only show the observed fire rotation for 19 subregions of Alaska (Figure A2 in supplement) with 60 years of fire occurrence data, but also project future rotations under various climate scenarios (in this case a mean of of 5 global climate models).

The use of advanced statistical models to build fire-landscape response models for boreal forest and tundra reaffirms prior findings of the sensitivity of fire regime to summer temperatures and moisture deficit. However, the effect is not uniform among regions: they identify a threshold at about 56⁰ F (30-yr mean temperature of the warmest month) and another threshold for annual precipitation where fire occurrence really seems to jump.  This latter finding accounts for results which project large increases in 30-year probability of burning for areas where these thresholds will be crossed in the next several decades.  For example, models project the Brooks Range foothills of the North Slope, Noatak tundra and the Y-K Delta may see increases in fire 4-20x greater than historical levels.  Some tundra areas are likely to experience fire frequency increase to levels not observed in the paleo record, spanning the past 6,000-35,000 years.  Across most of the boreal forest, fire rotation periods are projected to be less than 100 years by end of the 21st century.  This is useful information for natural resources management as well as fire protection agencies—a concise, well-researched, well-illustrated paper—put it on your summer reading list.

Young, A. M., Higuera, P. E., Duffy, P. A. and Hu, F. S. (2016), Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change. Ecography 39: 1-12. http://dx.doi.org/10.1111/ecog.02205

Climate Change and Fire May Impact Northern Alaska Caribou Herds

Boundary Fire near the Canadian border 2005 (Photo: Tony Chapman, BLM Alaska Fire Service)

Will climate-driven changes in fire regime affect the Porcupine Caribou Herd? Caribou actively seek out and rely on high-energy lichen-rich habitats in the winter, and these lichen stands–also known as “caribou moss”– are uniquely sensitive to fire, requiring 60-100 years to recover after burning. Alaska climate modelers and biologists teamed up to study predicted annual acreage burned in the ranges of two northern herds: the Central Arctic Herd and the Porcupine Caribou Herd (of Arctic National Wildlife Refuge fame). Using newly developed models of wildfire response to climate changes, Gustine et al. (2014) modeled burn acreage in the next few decades under two possible climate trajectories: let’s call them “warm” or “hot”. Under the “warm” scenario they found little change through 2090 in the total old-growth habitats available to caribou of either herd. However, the “hot” climate scenario indicated fires grew larger, increasing average area of winter habitat that burned per decade. In brief, the Central Arctic Herd lost 11% of their winter habitat and the Porcupine Herd lost 21% through 2090 under the “hot” scenario. In addition, 30% of the Porcupine Herd’s current spruce forest habitat changed to a younger forest type or tundra. While biologists continue to debate how much habitat is required to sustain herds at present levels, habitat loss is rarely beneficial and availability of old-growth lichen stands is a big driver of caribou use patterns in most Alaska herds. If we humans have the power to rein in the pace of climate change to the “warm” scenario by slowing our greenhouse gas emissions, the caribou would probably appreciate it. This short illustrated paper is open access—read the whole research article at:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0100588

Citation: Gustine, D.D., Brinkman, T., Lindgren, M., Schmidt, J.I., Rupp, T.S., and Adams, L.G., 2014, Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic: PLOS One, v. 9, no. 7 100588, doi:10.1371/journal.pone.0100588

Upcoming webinar: Effect of Tundra Fires on Post-fire Vegetation

Teresa Hollingsworth, USFS and Amy Breen, UAF-SNAPTundra_Fire

 

Apr 28, 2014  2:00 pm – 3:00 pm  AK time. Register.

https://akfireconsortium.uaf.edu >> Events

Amy and Teresa will summarize the history of tundra fires in Alaska and share preliminary results of their research to characterize post-fire plant communities, quantify fuel accumulation, and model tundra fire regimes and vegetation dynamics.

Find the recorded webinar <HERE>.

 

New 5-yr Arctic Research Plan calls for more research on fire in Alaska’s tundra ecosystems

Fire in Alaska’s tundra ecosystems is getting more attention as a potentially important factor in climate change.  A 5-yr US Arctic Research Program Plan just released by the Interagency Arctic Research Policy Committee specifically calls for investigating the frequency and severity of wildland fires in the Arctic. It mentions recent research findings from the 2007 Anaktuvuk River fire as well as the climate modeling work of SNAP and socio-economic impacts of climate change on Alaskan arctic communities.  The IARPC reports to the President’s National Science and Technology Council Council who coordinates policy across agencies and set goals for Federal science and technology investments so their endorsement is potentially an important boost for researchers competing for funding.  You can review the plan yourself at: http://www.whitehouse.gov/sites/default/files/microsites/ostp/2013_arctic_research_plan.pdf

RJ-ARF-2008

Examining fire effects in tundra 1 year after the 2007 Anaktuvuk River Fire on Alaska’s North Slope.

Tundra burning in Alaska: Rare events or harbinger of climate change? Join the Webinar!

The 2007 Uluksian Fire (photo courtesy of P. Higuera).

Dr. Philip Higuera (assistant professor at the College of Natural Resources, University of Idaho) will be joining us for a webinar on May 24, 2012 (1:00-2:00 pm AKDT) entitled “Tundra burning in Alaska: Rare event of harbinger of climate change?”.  Philip’s current research is focused on how climate, vegetation, and human activities interact with fire occurrence and fire regimes (from across years to across millenia).  He is also the Director of the Paleoecology and Fire Ecology Lab  where students and researchers work on charcoal and pollen analysis in lake-sediment records,  dendrochronology, and spatially-explicit modeling and analyses for areas in the US Rocky Mountains, Alaska, and abroad in Tasmania, Australia.

Link to recording <HERE>

Webinar at a Glance:

Dr. Philip Higuera will be presenting results from past and ongoing research focused on understanding the causes and consequences of tundra burning in the past, present, and future. The talk will integrate several lines of work, including reconstructing tundra fire history in the recent and distant past (2000-14,000 yr), quantifying relationships among modern climate, vegetation, and tundra burning, and anticipating future tundra burning given future climate scenarios.

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Local Alaskan Scientist Featured in New York Times: “As Permafrost Thaws, Scientists Study the Risks”

Methane Hot Spots, South Central Alaska, January 2010 (Photo by Marie-Laure Geai)

Local scientist Katey M. Walter Anthony (Aquatic Ecosystem Ecologist at UAF) has been studying the amount of methane gas being released into the atmosphere from thawing permafrost. As long frozen plants and other organic materials begin to thaw, they also begin to decay, producing methane gas. Katey has been collecting gas samples from frozen “bubbling” lakes near Fairbanks, Alaska to see just what we’re up against.

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6,000 Years of Tundra Fires in Noatak National Preserve

One of the 37 tundra fires that burned in Noatak National Preserve in the summer of 2010. The Kaluktavik River fire (Fire #561) burned more than 23,000 acres (9,300 ha) in July. Photo from Alaska Park Science.

Excerpt from: Higuera, P., Barnes, J., Chipman, M., Urban, M., and F.S. Hu. The Burning Tundra: A Look Back at the Last 6,000 Years of Fire in the Noatak National Preserve, Northwestern Alaska. Alaska Park Science 10 (1):  36-41.

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“Recovery After World’s Largest Tundra Fire Raises Questions”

From the Alaska Science Forum by Ned Rozell:

Four summers ago, Syndonia Bret-Harte stood outside at Toolik Lake, watching a wall of smoke creep toward the research station on Alaska’s North Slope. Soon after, smoke oozed over the cluster of buildings.

The great Anaktuvuk River tundra fire of 2007. Photo by Michelle Mack. (From Alaska Science Forum)

To read more of this article click here or visit the Alaska Science Forum website to view all of Ned’s recent articles.

What to know more?  Check out our previous post on the Anaktuvuk  River Fire with links to Michelle Mack’s research findings and other news articles.