Grow or Burn?

Understanding the paradox of fire exclusion in the WUI



By Dena Ali | FireRescue Magazine Volume 12, Issue 11

According to the federal register of the United States, the wildland-urban interface (WUI) exists where humans and their development meet or intermix with wildland fuel.1 Places referred to as the WUI include forests, grasslands, shrub lands, and other natural areas. Currently, approximately 33 percent of United States homes are located in the WUI and, since 1990, 60 percent of new homes nationally have been built in the WUI. There are many reasons for WUI growth including population growth and shifts from the eastern United States to a still-growing west and south.2 Baby boomers are retiring and moving to small, more rural communities close to scenic natural resources. (2) Moreover, the WUI provides easy access to recreation, scenery, lower property cost, and privacy.

This growth comes at a cost to the environment and to the firefighters who protect lives and property in the WUI. Evaluation of more than 1.5 million government records of wildfires extinguished or managed by state and federal agencies from 1992 to 2012 found that humans have caused 84 percent of wildfires during that 21-year period.3 Historically, lightning was the primary cause of wildfires and the season for wildfires was limited to summer. Human-related ignitions have nearly tripled the length of wildfire season. Of all fires ignited by lightning, 78 percent occurred in the summer. In contrast, human-ignited wildfires were more evenly distributed throughout the year, with only 24 percent occurring in the summer. (3)

Fire And The Ecosystem

Historically, fire has played an integral part of the ecosystem in many North American wildland areas by stimulating growth of trees and other plants. Low fire burns off excess fuel, cleans out underbrush, and allows wildlife to flourish. According to the United States Forest Service (USFS), fire-dependent ecosystems rely on fire to do the following:

Regenerate woodlands and native plants.

Reduce hazardous fuels.

Minimize the spread of pests, insects, and disease.

Improve habitat for threatened and endangered species.

Recycle nutrients back to the soil.

Promote the growth of trees, wildflowers, and other native plants.

Sequester carbon to produce energy.

Fire is a fundamental ecological component for 94 percent of wildlands across the United States. (2) Growth into the WUI during the 20th century resulted in policy-driven fire suppression in these fire-dependent ecosystems.4 As a result, fire became perceived as a destructive force and policies were designed to accommodate and protect people living in the WUI through smoke management and wildfire prevention. But this practice has left dead trees, forest litter, and aging forests that are prone to disease and invasive insect damage, such as pine beetle infestations, and are perfect ignition material.5 Basically, the reduction in fire frequency has damaged forests and resulted in an abundance of fuel accumulation through overgrowth. (4) Mark Heathcott, a fire expert who has managed Parks Canada controlled burns for more than 20 years, says suppression is “a setup for huge fires.” (5) Many fire experts are blaming misinterpretation of “Smokey Bear” and our fear of fire for our current wildfire problem.

A combination of human settlement into fire-prone vegetation (WUI), fuel accumulation, and climate change has contributed to more severe and more difficult to control wildfires. This problem can be mitigated with hazardous fuels reduction through prescribed fires and widespread prevention efforts aimed at those who live in the WUI. Extensive research has further found that the most effective means of reducing high-severity wildfire risk is forest thinning coupled with prescribed burning.6(4) While factors such as climate change, insect infestation, and drought contribute to incidence of severe wildfire events, fuel reduction is the only of these factors that can be effectively managed. The USFS reported in a recent assessment that 90 percent of fuel treatment efforts conducted on national forests were effective in reducing the intensity of wildfires.

2017 North American Wildfire Season

The record rain and snowfall that fell last winter in the mountains ended California’s six-year drought. However, it also led to heavy fuel loads of grasses and brush that increased the challenge for fire crews tasked with suppression during this summer’s dry heat. Smaller fuels such as grasses dry out quickly and burn quickly and hot, leading to more severe wildfires. At the time of this writing, the WUI near the town of Mariposa, California, was experiencing the worst of these wildfires. In a short period of time, the wildfire consumed 110 square miles and 99 structures and threatened at least 1,500 homes. By July, 6,000 firefighters from all over the nation were battling 17 wildfires in the state of California. Fortunately, wet spring and summer conditions in the southeastern United States helped to mitigate this year’s spring and summer wildfire season for eastern states. But, the fuel load in this area is expected to increase as a result of the plentiful rain.

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History of United States Wildland Fire Management

Records from more than 400 years of fire-adapted tree-ring data show that climate-synchronized fire occurrence across the Southwest consistently reoccurred at intervals ranging from two to 25 years, depending on the species. (4) Additionally, during the years prior to European settlement, Native Americans used fire extensively as an agricultural tool and to create hunting habitats. (2) By the 1900s, fire was used by settlers to reduce vegetation and decrease the amount of potential fuel for future wildfires. (2) In the early 20th century, America became dependent on wood resources, and fuel reduction was considered a waste of valuable economic resources. (2)

In 1910, a wave of wildfires burned more than three million acres in the western United States and killed 78 firefighters, resulting in federal and state policies aimed at rapid suppression of all wildfires. This policy-driven fire exclusion had an unexpected effect by damaging fire-dependent wildlands and causing buildup of flammable materials (increased fuel load). These unhealthy forests were also prime feeding grounds for insects and diseases that killed many trees, further exasperating the situation. These dangers were not recognized for several decades. By the 1970s, wildfire management policy evolved through the efforts of land managers, scientists, and the public, who better learned the role of fire in many wildland ecosystems. (2) As a result, fire has been reintroduced through carefully controlled prescribed burns in certain areas. (2)

However, because of wildfire suppression efforts, around 30 million hectares of national forest land in the United States meet high priority for treatment of fuel buildup in WUI areas. (1) According to the USFS, decades of fire suppression/exclusion have resulted in a record abundance of fuel around many communities near federal lands that are at risk to large conflagration.7 This is the suppression paradox that has contributed to the dangers to civilians and firefighters in the WUI.

Mitigating Wildfire Risk

Fire mitigation in the WUI is unique because it requires a combined approach to mitigation at all levels of land management: local, state, tribal, and federal. Mitigation occurs prior to suppression activities as a preventive measure. Communities, organizations, fire suppression agencies, and property owners must work together to build partnerships aimed at developing fire-adapted communities. According to Terri Jenkins, fire management specialist with United States Fish and Wildlife Service, every dollar spent on prevention can save $35 in suppression. She says prevention is necessary because humans are the root cause of fire: “We start fires, we cause fires intentionally or inadvertently, we build homes in the way of fire, we don’t use prescribed fire, and we don’t use natural fire like we should.”8

A fire-adapted community is defined as a human community consisting of informed and prepared citizens collaboratively planning and acting to safely coexist with wildland fire. Successful fire-adapted communities have the potential to save lives, homes, and millions of dollars in suppression costs annually. Elements of a fire-adapted community include the following:

Ignition-resistant structures, building materials, and landscapes.

Fuel treatments on public and private lands.

Codes and ordinances to foster development in the WUI that reduces fire risk.

Collaboration between jurisdictional authorities.

Evacuation planning.

Education on wildfire prevention and preparedness.

One of the most useful resources for WUI fire prevention is the National Fire Protection Association (NFPA) Firewise USA program ( It’s a key component of fire-adapted communities and provides a collaborative approach connecting all those who participate in wildfire education, planning, and action with resources to help reduce risk. Firewise provides homeowners with concepts aimed at helping them reduce risk to their homes and neighborhoods by educating them on the basics of defensible space and the “home ignition zone.” ( The program teaches that the home ignition zone includes the home and up to 200 feet beyond the structure. Managing fuels such as plants, high lawns, and large trees can serve as a huge protectant for these homes. Having a nonflammable roof covering and other building material is another enormous safety measure. Firebrands have the potential to travel long distances and have been found to cause at least 50 percent of home ignitions, with the roof being a primary target or culprit. (1) In fact, the devastating 2016 Gatlinburg wildfires started in the Great Smoky Mountains and embers traveled six miles to Gatlinburg during an extreme wind event.

Recent research of the WUI community in the Log Hill Mesa Fire Protection District of Ouray County, Colorado, found that the public tends to significantly underestimate overall risk relative to the risk assessed by fire professionals.9 In the evaluation, more than half the respondents rated their property at lower risk than the professionals found. Properties found to be “high risk” were often rated as “moderate risk,” and this gap extends to individual property attributes such as flammability of home’s exterior and deck, the distance to flammable vegetation, and other combustibles. (9) These results demonstrate the important implications for wildfire risk mitigation policy and the need for a collaborative prevention approach between the community and fire suppression personnel. Individual fire departments can schedule a Firewise course for their agency and become more empowered to educate residents in their jurisdiction. Go through state and federal forestry agencies for these courses.

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Severe Wildfires

The 2017 wildfire season was particularly severe in the Southwest. A combination of extreme heat, dry conditions, and abundant growth of grasses from heavy winter rains produced prime wildfire conditions fueled by dry, overgrown grasses. Additionally, approximately three percent of wildfires are responsible for 97 percent of the area burned in the United States. (1) (6). These most damaging wildfires typically occur during extreme weather conditions when high winds interact with low fuel moisture. (6) Low fuel moisture occurs during drought conditions as a result of poorly managed fire-adapted forests or ecosystems infested with insects. (6)

Fuel moisture is one of the most important fuel characteristics for fire occurrence, spread, and intensity; reduced fuel moisture in the southwest made for prime wildfire conditions. Areas found with the lowest fuel moisture are termed “target conditions” for fuel treatment. The single most important treatment for these conditions is surface fuel removal by prescribed fire. (6) The amount of fire depends on the treatment area, and many trees can survive fires that do not ignite foliage and use flame lengths less than four feet. (6)

Wildfire Vs. Prescribed Fire Environmental Impact

Wildfires are responsible for about one-third of the total carbon emissions worldwide.10 Wildfires release large amounts of particulate matter (PM) and other air pollutants, which degrade air quality. Smoke can affect public health, transportation, and the health and well-being of firefighters. These negative effects are attributed to policies surrounding the exclusion of fire in and around the WUI.

Recent research conducted by the Biomass Burning Observation Project and Studies of Emissions and Atmospheric Composition evaluated the emission factors and PM from three wildfires in the western United States and compared them to previous measurements of temperate wildfires and prescribed fires. The wildfires were found to emit more than three times the amount of PM and an average of more than two times the emissions as compared to prescribed fires.11 Results from this research determined that prescribed burning may be an effective method to reduce fine particle emissions during wildfires. (11)

Healthy fire-adapted forests sequester carbon, and this sequestration reduces the atmospheric carbon dioxide concentration. Because wildfires release significant amounts of emissions into the environment, fire-adapted systems rapidly re-sequester carbon through forest growth and mitigate damage to the atmosphere. (4) These findings suggest that the practice of prescribed burning not only reduces the impact of PM on air quality but can also significantly reduce wildfire events. (11)
Wildland Firefighting Factors

Because of the dangers and unpredictability of wildland firefighting, prevention planning must include firefighter safety. Local laws should include addressing defensible space, ingress, egress, and water supply with the focus of creating a safer environment for firefighters. Between 2002 and 2012, an average of four wildland firefighters died in the United States at wildland fires annually. (1) Tools are available to predict the spread of wildland fires and their intensities, but they are based on assumptions of steady flame spread that have limited or no physical basis. (1) The fire dynamics used to analyze structural fires are also limited when applied to WUI fires. There are new tools under development aimed at eliminating these gaps, such as a WUI Fire Dynamics Simulator. However, the technology is incomplete and the interactions between climate, fire, and vegetation growth provide a great uncertainty in projecting future fire activity. (4) One thing is certain: Regional warming, extreme wind and weather events, and human expansion are creating conditions that amplify wildfire dangers into the WUI.
Fire Department Wildfire Preparedness and Readiness Capabilities

In January 2017, the NFPA issued a report designed to improve wildland firefighter safety response based on interviews with 46 fire chiefs and senior line officers. The following was one key finding of the report:

“The majority of fire officials interviewed said that experiencing a large wildfire event has increased their awareness of the need for additional wildland firefighting training and stricter fitness requirements. However, even when senior officers recognize these needs, they still face obstacles including availability of resources and funding, organizational structure and culture, and personnel resistance.”12

The following are key highlights from the report:

Budget constraints prohibit the purchase of full, up-to-date wildland personal protection equipment assemblies for every wildland firefighter.

Urban, rural, and volunteer fire departments are increasingly comanaging fire in the WUI but need to transition from traditional training practices to wildland fire training.

Standard requirements for health and fitness vary by jurisdiction and among career vs. volunteer firefighters.

The following are key report statistics:

30 percent of departments surveyed do not have a wildfire preattack plan.

37 percent of fire departments surveyed do not have a firefighter fitness program.

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54 percent of departments surveyed that have fitness programs do not use the USFS pack test designed for wildland firefighters.

68 percent of departments surveyed have firefighters who use chainsaws who aren’t certified fallers.

Other findings from the report include the following:

Consensus reported a positive effect that community risk reduction efforts had on mitigating the risks of major wildfire events and preventing the loss of homes.

Many departments stressed the importance and effectiveness of meeting in person and talking face-to-face with residents, businesses, and political leaders.

Radio technology is critical for departments responding to WUI fires.

There is a need for volunteer firefighters to receive wildland training.

There is inconsistent adoption of WUI fire training among local and regional responders.

Firefighter fitness levels at times are inadequate for the rigors of WUI fires.

A review of several recent wildfires necessitating response from multiple jurisdictions all indicated a need for better communications. A need for region-wide communication to coordinate team efforts and reduce duplication of efforts was cited as one of the greatest lessons learned at the fall 2016 Party Rock fire in North Carolina. Google Drive was used during this event to help disseminate information among all agencies.

Success Has Led to Problems

Paradoxically, wildfire suppression and exclusion aimed at eliminating damaging wildfires has ensured the inevitable occurrence of these fires. A combination of human settlement into fire-prone areas (WUI), fuel accumulation, and climate change has contributed to more severe and more difficult to control wildfires.

Because the primary responsibility for preventing WUI home destruction lies with homeowners, wildfire mitigation can only be successful with the collaboration of private homeowners, firefighters, federal, state, and local authorities. The North Carolina fire service has a course, “Wildfire Suppression for Volunteer Fire Departments,” that is conducted across the state when requested. Prevention has the greatest potential to reduce the incidences of wildfires and to protect the lives of firefighters and homeowners living in the WUI. Fire-adapted communities are designed to educate residents and firefighters on methods of working collaboratively to prevent wildfire events through public education and prescribed burning. Additional information on fire-adapted communities can be found at the NFPA Web sites and


1. Caton, Sara E., Raquel S. P. Hakes, Daniel J. Gorham, Aixi Zhou, and Michael J. Gollner, “Review of Pathways for Building Fire Spread in the Wildland Urban Interface Part I: Exposure Conditions,” Fire Technology, 53.2 (2016): 429-73. Web.

2. Stein, S. M., J. Menakis, M. A. Carr, S. J. Comas, S. I. Stewart, H. Cleveland, L. Bramwell, and V. C. Radeloff, “Wildfire, wildlands, and people: understanding and preparing for wildfire in the wildland-urban interface – a Forests on the Edge report,” (2013): 1-40. Web.

3. Balch, J.K. et al., “Human-started wildfires expand the fire niche across the United States,” Proceedings of the National Academy of Sciences, 2017, 114 (11), 2946-2951.

4. Hurteau, Matthew D., John B. Bradford, Peter Z. Fulé, Alan H. Taylor, and Katherine L. Martin. “Climate change, fire management, and ecological services in the southwestern US.,” Forest Ecology and Management 327 (2014): 280-89. Web.

5. Brend, Yvette, “Fight fire with fire: How First Nations practice of burning the land helps prevent megafires,” CBCnews, CBC/Radio Canada, 17 July 2017.

6. Calkin, D. E., J. D. Cohen, M. A. Finney, and M. P. Thompson, “How risk management can prevent future wildfire disasters in the wildland-urban interface,” Proceedings of the National Academy of Sciences 111.2 (2013): 746-51. Web.

7. Cova, Thomas J. “Public Safety in the Urban–Wildland Interface: Should Fire-Prone Communities Have a Maximum Occupancy?” Natural Hazards Review 6.3 (2005): 99-108. Web.

8. Jenkins, T., (2017, July 11) Fire Prevention Education Teams: Lessons Learned from the 2016 Appalachian Wildfires, Address presented at Webinar Portal for Forestry and Natural Resources. Retrieved from

9. Meldrum, J.R. et al., “Understanding Gaps Between the Risk Perceptions of Wild-Urban Interface (WUI) Residents and Wildfire Professionals,” Risk Analysis 35, no.9 (2015): 1746-761.

10. Liu, Y., Goodrick, S.L, Stanturf, J.A., “Future U.S. wildfire potential trends projected using a dynamically downscaled climate change scenario,” Forest Ecology and Management 294 (2013): 120-135. Web.

11. Liu, Jiaozi et al., “Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications,” Journal of Geophyisical Research: Atmospheres, 122, 6108-6129.

12. Hayes, H., & Madsen, R., (2017), Wildland Urban Interface: Fire Department Wildfire Preparedness and Readiness Capabilities (pp. 1-79, Rep.) NFPA.


Dena Ali is a captain with the Raleigh (NC) Fire Department and intermediate with Wake County EMS. Prior to becoming a firefighter, she served five years as a police officer in North Carolina. Ali has a degree from North Carolina State University. She is a graduate student at UNCP, and her research focuses on firefighter suicide. Ali taught her class on suicide prevention at FDIC International 2017. She is an avid cyclist and founding member of the Carolina Brotherhood. Ali also serves as an advocate for 555fitness.


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Understanding the paradox of fire exclusion in the WUI     By Dena Ali | FireRescue Magazine Volume 12, Issue 11 According to the federal register of the United States, the wildland-urban interface (WUI) exists where humans and their development meet or intermix with wildland fuel.1 Places referred to as the WUI include forests, grasslands, […]

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