This Research Brief covers a new NASA-funded study led by Sander Veraverbeke of Vrije Universiteit in Amsterdam which found lightning storms to be a main driver of recent large fire seasons in Alaska and Canada. Results of the study are published in the July, 2017 issue of Nature Climate Change.
MODIS (Moderate-Resolution Imaging Spectroradiometer) satellite images and data from ground-based lightning networks were employed to study fire ignitions. Sander’s analysis found increases of between two and five percent a year in the number of lightning-ignited fires since 1975. Veraverbeke said that the observed trends are consistent with climate change, with higher temperatures linked to both more burning and more thunderstorms.
Study co-author Brendan Rogers at Woods Hole Research Center in Massachusetts says these trends are likely to continue. “We expect an increasing number of thunderstorms, and hence fires, across the high latitudes in the coming decades as a result of climate change.” This is confirmed in the study by different climate model outputs.
Charles Miller of NASA’s Jet Propulsion Laboratory in California, another co-author, said while data from Alaska’s agency lightning networks were critical to this study, it is challenging to use these data to verify trends because of continuing network upgrades. “A spaceborne sensor that provides lightning data that can be linked with fire dynamics would be a major step forward,” he said. Such a sensor exists already– NASA’s spaceborne Optical Transient Detector –but it’s geostationary orbit limits its utility for high latitudes.
The researchers found that the fires are creeping farther north, near the transition from boreal forests to Arctic tundra. “In these high-latitude ecosystems, permafrost soils store large amounts of carbon that become vulnerable after fires pass through,” said co-author James Randerson of the University of California, Irvine. “Exposed mineral soils after tundra fires also provide favorable seedbeds for trees migrating north under a warmer climate.”
The extent and frequency of wildfires in Alaska’s boreal forest are predicted to increase in the coming century. In addition to natural sources of ignition, military lands in Interior Alaska are vulnerable to human ignitions due to their proximity to the road system and training activities. Recent wildfires—such as the 2013 Stuart Creek fire, which consumed nearly 365 km2 (90,000 acres), cost over $20 million to fight, and was sparked by an explosive ordinance on an army weapons range—demonstrate the need to test alternative fire management scenarios. One method that might reduce future large fires is to increase the level of fire suppression by changing the fire management planning options (FMPOs) for these areas from mostly Limited to Full protection. But will that method work well long-term?
You might be surprised by the amount of collaboration between Alaska and Michigan-based scientists over the last 2 decades! This has been a long-standing research relationship which has spawned many useful products–including Alaska’s fire perimeter map database! Other endeavors include satellite fire detection and mapping, fuel moisture detection, improvements in fuels mapping, tundra fire research and more. Read about the history of this research relationship and its important findings and products, still ongoing with some exciting current research endeavors in this Research Brief.
Eric Miller, BLM Alaska Fire Service Fire Ecologist, assists with a lot of prescribed burns on military training ranges in Alaska where the primary fuel is standing dead grass and this question was often on his mind. He found that existing fine dead fuel moisture tables underestimated the moisture content in dead grass. Six years and 74 prescribed burn days later he had collected 409 grass samples and 285 weather observations, enough to build several empirical- and process-based fuel moisture models. He gave a presentation on his findings at the Alaska Fire Science workshop in April 2015 and prepared a 1-page research brief on the highlights of his study.
Eric introduced a simple “Rule of Thumb” for predicting dead grass moisture content in the field: MC = rH/5 + 4
Fire Severity Filters Regeneration Traits to Shape Community Assembly in Alaska’s Boreal Forest: A recent paper by Hollingsworth et al. (2013) proposes that fire severity and a plant’s intrinsic regeneration strategy are key determinants in post-fire community recovery. The authors identify species that may fare better or worse with predicted changes in Alaska’s fire regime. Hollingsworth–who is based at the University of Alaska-Fairbanks–bases her findings on a large (n = 87) and geographically diverse set of post-fire plots in interior Alaska boreal forest.
Hokkaido University (HU) is one of the world leaders in developing new earth-observing space technology. Dr. Koji Nakau leads their wildfire remote sensing applications team. He’s working with various partners—including UAF—on new satellite-derived products delivered to wildland fire managers in Alaska and around the world. They are especially excited about the May 24th (2014) launch of a rocket carrying ALOS-2 (Advanced Land Observing Satellite) which is also carrying a couple microsatellites with sensors specifically designed by his team to detect wildfire signatures. In addition to improving real-time operational support, satellite data is analyzed in support of wildfire propagation modeling, smoke transport, fuels estimates, and post-fire ecology.
Dr. Matt Nolan shared results from his recent airborne photogrammetry campaigns in Alaska, and related them to possible fire and forest management applications in a webinar on February 25, 2014. There is now a 2-page Webinar Summary about the topic and you can also watch the recorded webinar (https://vimeo.com/87797023) on AFSC’s website. Dr. Nolan is a Research Associate Professor at UAF’s Institute of Northern Engineering with degrees in geophysics and arctic and mechanical engineering. He’s been pioneering new high-tech uses of an old tool—the aerial photo. With new advances in computer processing and display technologies, airborne Digital SLR Photogrammetry is an even more powerful tool for field sciences, especially in remote areas like Alaska. Compared to LiDAR (Light Detection and Ranging, or aerial 3D laser scanning), the low cost of DSLR photogrammetry makes it more affordable to make time-series of high-resolution maps, opening up new possibilities for analyzing and understanding changes in the environment. Forest inventory, fire fuels assessments (like canopy height), snow depth, and post-burn vegetation recovery and monitoring are just a few examples of applications that could benefit from time-series of topographic measurements on an annual, monthly, or other repeating basis.
The Joint Fire Science Program is doing a nation-wide survey this spring (2014) to ask managers whether sponsored research in their respective regions has improved management decisions or is useful to fire management practices. We started thinking about this for Alaska and prepared a 2-page review of a sample of four projects dating back to 2002 to see whether they have had any impact on management in Alaska, and what their outcomes appear to be today. Principal investigators included Scott Rupp (UAF), Phil Higuera (University of Idaho), Dan Mann (UAF), and Teresa Hollingsworth (USFS-Fairbanks). Read our review and see if you think these projects were indeed worthwhile!
Wildfires are a natural part of the boreal forest ecosystem. Fires are necessary for maintaining vegetation diversity and provide a diverse habitat for wildlife, but fires can also present a threat to human values. Alaska has seen a recent increase in the frequency of large fire years, with three of the top ten largest years (since 1940) occurring in the last decade. Over the past 50 years, Alaska has warmed at more than twice the rate of the rest of the United States. Warmer temperatures have lead to longer snow-free seasons, changes in vegetation, and loss of ice and permafrost, all of which can contribute to longer and more active fire seasons. It is likely that the Alaskan boreal forest will experience some dramatic changes over the next century. Learning about these changes and their potential impacts can help guide us in planning for the future.
Climate, Fire, Frost and the Carbon Bank: This 2-page research brief summarizes several years of field studies–citing recently published articles–by USGS soil scientists Jennifer Harden and Kristen Manies. Their studies shed new light on the impact of fires on permafrost in Alaska boreal forest, and interactions of fire effects and freezing effects on the forest floor. The insulating moss/duff layer plays a critical role in protecting permafrost and conditions suitable for the rapid regrowth of permafrost are keys to determining whether boreal forest will retain its ability to store large amounts of biomass carbon.