Living with Wildfire: Colorado Front Range Disasters
Understanding the Impact of Forest Management on the Cameron Peak and CalWood Fires
NASA DEVELOP National Program (Colorado Node) in partnership with Colorado State University, Colorado Forest Restoration Institute, Colorado State Forest Service, The Nature Conservancy (Colorado), The Coalition for the Poudre River Watershed, and Ben Delatour Scout Ranch
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Introduction
The 2020 wildfire season in Colorado was a succession of record-breaking fires, smoky skies, and scrambling evacuations. The Cameron Peak Fire and East Troublesome Fire in northern Colorado and the Pine Gulch Fire in southern Colorado set records as the largest fires ever recorded in the state's history. Collectively with smaller fires, wildfires charred over 650,000 acres across the state, and imposed serious safety concerns, widespread evacuations, and filled the skies with smoke.
Smoky skies captured from the Horsetooth Reservoir Natural Area West of Fort Collins, Colorado. Image Credit: J. Klisauskaite
The unprecedented fires in 2020 have gained significant attention and have revealed critical questions about past forest management efforts and their impact. Given that large areas were previously treated within the fire perimeters, the NASA DEVELOP team sought to examine the relationships between different treatment methods and burn severity within the Cameron Peak and CalWood Fires. Scroll to learn about these findings and what they mean for Front Range forests and management going into the future.
The Colorado Front Range
The Front Range spans from central Colorado to southeast Wyoming and is situated between the easternmost edge of the Rocky Mountains and the western limit of the Great Plains. Elevations range from roughly 1,500 to 4,300 meters above sea level and are home to many different species of plants and animals.
Fire Ecology and Public Perceptions
Wildfire is a natural process that has many impacts on the landscape: it limits fuel build-up, increases biodiversity and soil fertility, and alters species community composition. As people in the front range have moved closer to the wildland-urban interface (WUI), fires causing property damage and personal harm have led to the suppression of fire throughout forests in the western United States.
Cameron Peak surface fuels fire near Larimer County, Colorado. Image Credit: S. McKinney
More recently, we have realized the critical importance of fire as an ecological process and have attempted to replicate natural fire regimes through fuel treatment and prescribed burning, especially near the WUI. Public acceptance of fuel reduction treatment often varies due to a variety of social implications, including past negative perceptions of fire and forest treatment.
History of Fire Exclusion
The negative perceptions of wildfire resulted in a one-size-fits-all fire exclusion policy across the western US in the early 20th century. Past efforts to eliminate fire from the landscape have deprived many ecosystems of the critical process of a wildfire. As a result, many forests have become unnaturally dense and prone to further disturbance.
Aerial image of forested area burned by the Cameron Peak Fire near Red Feather Lakes, Colorado. Image Credit: N. Swayze
The 2020 Fire Season
The 2020 fire season was a series of megafires outside the bounds of previously seen historic trends. Interactions between large bark-beetle-infested tree stands, high wind conditions, drought, and fire suppression throughout the 20th century resulted in record-breaking areas burned in 2020.
In the same manner, the timing of the 2020 wildfires is off the charts. According to the Rocky Mountain Area Coordination Center fire data, 2020's fires burned much later in the season. The figure below was created in October 2020 while the wildfires were still ablaze and show when these fires started. June has historically been known to be the worst month for wildfires. However, for the first time in Colorado history, this trend shifted towards August with the fire season extending from May into December.
Figure 1: Interactive comparison of large Colorado wildfires by month. Figure Credit: J. Ingold, 2020
Community Concern
The Colorado Front Range provides a bounty of ecosystem services, habitat for native species, and recreation opportunities. The area is heavily utilized by surrounding communities and tourists. Extreme wildfires increase risks to freshwater resources, carbon storage, and wildlife habitat, while also increasing erosion and flooding potential. Large wildfires also pose risks to human infrastructure and health.
Smoke rising from the Cameron Peak Fire seen from the Ben Delatour Scout Ranch. Figure Credit: R. Sturtevant
Forest management and fuel treatments have been implemented in order to reduce these risks, but often have varying levels of acceptance by the community because they require timber harvesting, prescribed burning, and other activities that decrease tree density within forests (Addington et al., 2018).
Surface fire slowly crawling across the CalWood Fire, west of Boulder County, Colorado. Image Credit: S. McKinney
Cameron Peak Fire
- Location: Arapahoe and Roosevelt National Forests
- Acres Burned: 208,913
- Duration: August 13th - December 2nd, 2020
The Cameron Peak Fire took a long run just west of Fort Collins, Colorado. Fueled by bark beetle-killed trees, dry forest fuels, and winds over 70 mph, it charred 208,913 acres over a 112-day period.
The Cameron Peak Fire was first reported by a hiker on August 13th.
September 4th-7th: Within the last 3 days, the fire has burned 78,000 acres.
October 14th: The Cameron Peak Fire became the largest in Colorado history, aided by 70+ mile/hour winds.
164,140 acres have been burned so far.
November 2nd: The fire reached its maximum, burning 208,913 acres.
December 2nd: The fire was declared 100% contained. It had been 112 days since the beginning of the fire.
CalWood Fire
- Location: Boulder County
- Acres Burned: 10,106
- Duration: October 17th-November 14th, 2020
While the Cameron Peak Fire was still aflame, another wildfire ignited roughly 50 miles southeast in Boulder County, Colorado.
In the same vein as the Cameron Peak Fire, the CalWood Fire was largely driven by severe conditions. While this fire was relatively small, the fire spread quickly and became the largest wildfire recorded in the county.
October 17th: The CalWood Fire is first reported northwest of Boulder, Colorado. The fire burned 8,000 acres within 2 days.
October 26th: Thirteen inches of snow over the last two days halted the spread of the fire. CalWood was 100% contained on November 14th.
CalWood smoke plume near residential areas in Boulder County, Colorado. Image Credit: M. Brooks
What are Forest Fuels?
Fuels include any flammable material within a forest. They range from fine fuels such as needles and grasses to course fuels such as shrubs, branches, logs, and tree canopies.
Prescribed Burning Removal of forest fuels by burning excess organic debris. This is often done to emulate pre-fire suppression fire regimes where forest fires were historically common. Image Credit: National Parks Service and Bracewell
What are Forest Fuel Treatments?
Mechanical Fuel Reduction Removal of forest fuels by cutting, collection, thinning. Image Credit: Texas Forest Service
Forest fuel treatments are designed to reduce burn severity and mitigate the associated risks of wildfire. Treatments come in many shapes and sizes and are aimed at reducing or rearranging forest fuels. Some common practices include mechanical thinning, prescribed fire, and clearcut operations.
Assessing Relationships Between Burn Severity and Treatment Types
The NASA DEVELOP team used Sentinel-2 Multispectral Instrument (MSI) satellite imagery to map burn severity for the Cameron Peak and CalWood Fires. These maps were then validated using the soil burn severity field assessments to gauge accuracy.
Sentinel-2 MSI. Image credit: NASA
Landsat 8-Operational Land Imager (OLI) satellite imagery was used to detect past disturbance and recovery trends within the region using the LandTrendr algorithm.
Landsat 8-OLI Satellite: Image Credit: NASA
The Shuttle Radar Topography Mission (SRTM) digital elevation model was used to generate topographic variables such as elevation, slope, aspect, and others, which were used to model relationships between burn severity and environmental gradients.
Shuttle Radar Topography Mission Satellite. Image credit: NASA
Treatment Databases
Finally, treatments from state, federal, and county records were combined to evaluate how treated areas interacted with the two fires.
Analysis
The team used a random forest machine learning algorithm to detect trends between burn severity, treatment type, topographic, and disturbance variables.
Bringing it Together
Visual Comparisons
Figure 2. Visual comparisons of different treatment types for the Cameron Peak Fire, including previous wildfires, prescribed fires, clearcuts, pile and burn treatments, and all other treatments.
The team observed interesting trends where the 2020 wildfires interacted with different forest treatment categories. It was interesting to see the visual trends in burn severity change as the fires encountered different treatment types. In the examples above, previous prescribed fires and wildfires appeared to have lower burn severities than nearby areas.
Figure 3. Treatment type vs remotely sensed burn severity for the CalWood Fire.
For CalWood, fire-based treatments had slightly lower average burn severities than thinning-based treatments. These trends are preliminary for now and will require deeper digging to see if they are significant.
Figure 4. Treatment type vs remotely sensed burn severity for the Cameron Peak Fire.
In contrast with the CalWood fire, the results from Cameron Peak were more nuanced. Overall, fire-based treatments and thinning treatments varied widely, likely due to the sheer size of the fire and the elevational gradients within the burned area. However, these trends are preliminary for now and will require deeper digging to see if treatment types varied significantly.
Random Forest Modeling
Figure 5. Random Forest Modeling Results for the CalWood Fire. The results indicate that Forest Canopy Cover, Treatment Class, Aspect, Canopy Base Height, Vegetation Type, and Duration of Disturbance were the top six predictors for modeling burn severity. These relationships are still explorative and need to be investigated further.
Main Takeaways
Overall, the Colorado Front Range Disasters team had many important findings. While the relationships between burn severity and treatment type are still not clear for the Cameron Peak and CalWood fires, they have generated a number of end products. These include maps of burn severity for both fires, a well-organized treatment database, and preliminary visual and statistical results that will assist future research.
Researchers at the Natural Resource Ecology Laboratory will continue to explore the relationships between burn severity and treatment type for the Cameron Peak and CalWood fires. Other research will also investigate additional drivers of these fires to help guide management and restoration efforts to foster more resilient forests.
References
Addington, R. N., Aplet, G. H., Battaglia, M. A., Briggs, J. S., Brown, P. M., Cheng, A. S., Dickinson, Y., Feinstein, J. A., Pelz, K. A., Regan, C. M., Thinnes, J., Truex, R., Fornwalt, P. J., Gannon, B., Julian, C. W., Underhill, J. L., & Wolk, B. (2018). Principles and practices for the restoration of ponderosa pine and dry mixed-conifer forests of the Colorado Front Range. RMRS-GTR-373. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 121 p., 373. https://doi.org/10.2737/RMRS-GTR-373
Agee, J. K., & Skinner, C. N. (2005). Basic principles of forest fuel reduction treatments. Forest Ecology and Management, 211(1–2), 83–96. https://doi.org/10.1016/j.foreco.2005.01.034
Champ, J. G., Brooks, J. J., & Williams, D. R. (2012). Stakeholder understandings of wildfire mitigation: A case of shared and contested meanings. Environmental Management, 50(4), 581-597.
Gibbs, D., Lester, M. B., & Gibbs, D. (2020). We Must Do More to Match Our Forest Health Challenge. https://csfs.colostate.edu/media/sites/22/2021/02/CSFS_2020_Forest_Health_Report_WEB.pdf
Reinhardt, E. D., Keane, R. E., Calkin, D. E., & Cohen, J. D. (2008). Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western United States. Forest Ecology and Management, 256(12), 1997-2006.
Image Credits
DEVELOPedia. (2017). Landsat8 [Image]. Retrieved from. https://www.devpedia.developexchange.com/dp/index.php?title=List_of_Satellite_Pictures
DEVELOPedia. (2017). SRTM [Image]. Retrieved from. https://www.devpedia.developexchange.com/dp/index.php?title=List_of_Satellite_Pictures
DEVELOPedia. (2017). Sentinel2 [Image]. Retrieved from. https://www.devpedia.developexchange.com/dp/index.php?title=List_of_Satellite_Pictures
Jorune Klisauskaite. (2020). Cameron Peak smoke at the Horsetooth Reservoir. [Image].
Josh O’Connor (2009). Wildfire [Image]. CC by 1.0. Retrieved from. https://www.flickr.com/photos/usfwssoutheast/4971832860/in/photostream/
Malachi Brooks (2020). [Image]. Unsplash License. Retrieved from. https://unsplash.com/photos/-HVh7BRp3ls )
National Parks Service and Bracewell. (2020). [Image]. CC. Retrieved from. https://www.nps.gov/articles/what-is-a-prescribed-fire.htm#:~:text=Prescribed%20fire%20is%20a%20planned,of%20meeting%20the%20burn%20objectives
Neal Swayze. (2020). Aerial image of forested area burned by the Cameron Peak fire near Red Feather Lakes, Colorado. [Image].
Robert Sturtevant. (2020). Smoke rising from the Cameron Peak Fire seen from the Ben Delatour Scout Ranch. [Image].
Seth McKinney. (2020). Cameron Peak surface fuels fire near Larimer County, Colorado. [Image].
Seth McKinney. (2020). Ground fires slowly crawling across the CalWood Fire, west of Boulder County, Colorado [Image].
Texas Forest Service. (2021). CC BY 2.0. Prepare_Your_Home_for_Wildfires. [Image]. Retrieved from. https://tfsweb.tamu.edu/protectyourwildlands
Wade Tinkham. 2020. Post-fire conditions near the Colorado State University Mountain Campus. [Image].
