A prescribed burn on Loup Farm in Willamette Valley, Oregon

Understanding Wildfire: Human Contributions to, and Solutions for, Managing Fire-Prone Landscapes

Photo © The Nature Conservancy (Jason Houston)

Wildfire is becoming a household term throughout North America–millions of us have heard about it in the news, donated to recovery efforts, or have been directly threatened by active wildfires in the last year. Unfortunately, it is predicted that this kind of natural disaster is only going to become more prevalent and fierce in the future.open_in_new Wildfires are natural disturbances and, in some cases, critical processes, as certain plant species rely solely on fire for their reproduction. So, why does it seem fires are becoming more frequent and intense and how can we work to reduce this threat while retaining a healthy ecosystem?

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Photo © US Fish and Wildlife Services

Wildfires have always been, and will always be, a part of our natural landscape. Before human influence on natural environments, wildfires were common, frequent, and started with some regularity by lightning strikes. The frequency of these fires meant that fuel loads (available dry materials to burn) were low, which, for the most part, produced lower intensity fires. Humans have been suppressing wildfires for over a century, and as a result, many of our forest and grassland ecosystems are overgrown and full of fuel.

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Photo © Megan Whatton

80 percent of U.S. wildfires are caused by people

Center for Climate and Energy Solutions

An example of fire suppression effects on fuel load can be seen in the photo above. This is a picture of a forest in the panhandle of Florida (national capital of lightning strikes). To the left of the path, this section of forest hadn’t burned in 13 years. To the right of the path, this section of forest was burned within the last 3 years. Without fire, the fuels were able to grow denser and taller, providing more fuel, and creating potentially dangerous fire conditions.

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Wild oats (Avena spp) established alongside a residential community in Orange County, CA

Photo © Orange County Public Works

In addition to suppression, humans have also introduced and expedited the spread of invasive species. This poses two problems when it comes to wildfires. First, invasive plants species like wild oatsopen_in_new (Avena spp.), red brome (Bromus rubens), and foxtailopen_in_new have played a role in the spread, intensity, and possibly the ignition of devastating wildfires including the Thomas and Creek fires in Southern California in 2017-18. These invasive species have a different life cycle from their native neighbors. By late spring these plants seed and die, providing dry and highly flammable fuels during the summer and fall fire season.

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Photo © US Fish and Wildlife Service

Many native plants in California produce seeds that aren’t able to germinate before the fire season, meaning only the seeds from the invasive species can survive to propagate and spread. A similar situation is occurring in sagebrush ecosystems.open_in_new Cheatgrass (Bromus tectorum) is an invasive grass that provides dense fuels and ignites easily, creating three to five year burn cycles that outcompete the slower native species which take 10 years to establish.

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European Gypsy Moth (Lymantria dispar L.) deliberately brought to the U.S. for silk production, gypsy moths are one of the most destructive exotic forest pest in North America.

Photo © Wisconsin Department of Natural Resources

The second issue with invasive species is the spread of invasive insects (pictured: European Gypsy Moth Lymantria dispar L.) and disease. Many tree species have suffered over the past three decades from new pests and diseases which are estimated to have killed over 150 million trees.open_in_new Many of these pests and diseases are spread through the movement of firewood, hiking boots, wooden pallets, and nursery plants.

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Photo © USFS Region 5

One example is Sudden Oak Death (caused by Phytophthora ramorum),open_in_new which first came into focus in the mid-1990’s when nursery plants transported the disease into the U.S. most likely from multiple unknown locations. The list of oak (Quercus) and non oak species this disease affects is long; but, what is even more detrimental about this disease is that it not only kills oak species–which are important mast-producing resources in many ecoregions–it also changes the fire dynamic.open_in_new

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Photo © David Fulmer

First, the new dead wood from an infestation adds to the fuel loads in forests –increasing the chance of ignition, spread, and intensity of fires. Second, they take wildfires to new heights.open_in_new In the tanoak-redwood forests, tanoaks are highly susceptible to sudden oak death, and when fires come through, these dead trees act as a ladders, helping the flames reach the more vulnerable crowns of the redwoods. Burning dead tanoaks increase redwood mortality (an endangered species) four fold.

The birth of Smokey Bear

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Photo © USDA

In 1944 the U.S. Forest Service and the Ad Council created a fictional bear to represent a national effort in fire prevention. Six years later Smokey Bear came to life.open_in_new In the human-caused Capitan Gap Fire, located in Lincoln National Forest, New Mexico, 17,000 acres of forest burned. In the aftermath of the fire, firefighters found a young bear hanging on to a charred tree with burns on its paws and legs. They named the bear Smokey and his story spread nationwide. Smokey found himself a home at the National Zoo where he received honey and letters from his fans until his passing in 1976. Smokey Bear was returned to the Capitan Mountains and is buried in Smokey Bear Historical Park.

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Aerial view of some of the aftermath in Pike National Forest from the Hayman wildfire, 2002, Colorado's largest wildfire ever recorded.

Photo © The Nature Conservancy (Anne Shlisky)

The timing of wildfire season changes based on your location, temperature, and rainfall accumulation. Areas that are drier and experience longer periods between rain events have a higher risk of wildfire ignition. Between 1970 and 2017, wildfire seasons have grown, on average, 78 days longer.open_in_new This is, in part, due to climate change.open_in_new Areas that are experiencing earlier snowmelt are also experiencing longer, hotter, and drier conditions during their summer months, extending the fire season. Global fire models produced by University of California, Berkeley predict a 62% increase in fire probabilities in mid-high latitudes within the next 80-100 years.open_in_new Warmer climates are also known to aid in some invasive species spread, which only adds more fuel to the fire.open_in_new

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Fire running from open chaparral field into green timber. This forest burning originated by the Native Americans has been kept in action by the carelessness of white settlers. Image circa 1825

Photo © Internet Book Archive Image

Fire has been a tool of humans for a long time. There is evidence of the use of intentional burns in North America dating to well before European colonization where Native Americans were known to have used fire as a tool for cultivation and modification of the landscape.open_in_new Today, humans are known to fight fire, with fire.

Module Leader Jeff Crandall on Baskett Slough National Wildlife Refuge in Dallas, Oregon. In October 2016, The Nature Conservancy's Southern Rockies Wildland Fire Module traveled to the Willamette Valley in Oregon for three weeks to help the Oregon chaper

September 2015. Module Leader Jeff Crandall on Baskett Slough National Wildlife Refuge in Dallas, Oregon

Photo © The Nature Conservancy (Jason Houston)

Prescribed fires/burns (a.k.a control burns) are a land management technique to reduce the amount of fuel in an area.open_in_new By setting fire in a planned–down to every detail–and strategically-timed (weather) manner, humans can reduce fuel load and minimize out-of-control wildfire risk with the highest level of safety for the public and the fire staff in mind. Each prescribed fire must have both a fire management plan and a prescribed burn plan approved by the relevant governing entities (i.e. National Park Service). These plans take into consideration many factors including the fuel type, humidity, winds, temperature, time of year, fire breaks, smoke mixing heights/patterns, equipment-required, and staff–to mention a few. And, while controversial, prescribed burns do offer options for controlling fire risk in a changing environment.

Yurok forest managers create a “fire shade” to lessen the chance of wildfires. The Conservancy helped create a financial incentive mechanism for sustainable forestry and transformed and contributed to California’s climate change regulatory program.

Managers create a “fire shade” to lessen the chance of wildfires.

Photo © The Nature Conservancy (Kevin Arnold)

The White Mountain Stewardship Project is a perfect example of a town using fire to fight fire.open_in_new The Arizona Wallow Wildfire (2011) is one of the largest fires recorded in the state, burning 522,642 acres (2,115 km2). Ignited by campers in the White Mountains, this fire threatened the town of Alpine. Strategically, however, in 2004 the White Mountain Stewardship project initiated a 10 year plan to thin and burn a break (150,000 acres) between the forest and Alpine to protect against wildfires. As a result, the Wallow Fire surrounded the town of Alpine and would have consumed it without the efforts of the White Mountain Stewardship project, which are credited with protecting homes and businesses within the community.

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A prescribed burn in the Ossipee Pine Barrens

Photo © The Nature Conservancy (Eric Aldrich)

Prescribed fires are not only effective at reducing fuel loads, they are also used to bring natural processes back to our ecosystems. Without fire, habitats like oak savannas and pine barrens are lost to encroaching forests. Species like the Karner blue butterfly (Lycaeides melissa samuelis)open_in_new are lost when their host plant species, wild blue lupine (Lupinus perennis), are eliminated by habitat conversion that occurs in the absence of fires. Simply by introducing prescribed fires into these savanna and barren habitats- which were once maintained by wildfire and grazing/browsing wild animals- native process and species composition can begin to be restored.open_in_new

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Photo © Fire Adapted. ORG

Prescribed fires aren’t the only tool available to fight wildfires. Communities and private landowners can play a large role in wildfire preparedness. Programs like the Fire Adapted Communities Learning Network and Firewise are important resources to engage communities in fire resilience. These programs provide educational classes and workshops on wildfire safety and risk reduction actions geared toward homeowners.

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Demonstrations at Firewise Expo. One of these structures is well-prepared to reduce fire danger, the other not so much.

Photo © Paul Davis

For the individual homeowner, it is important to keep your home and the surrounding area as fire resistant as possible. According to the Firewise program, there are seven easy steps to reduce the risk of losing your home to wildfires.

Reduce your Wildfire Risk


  • CLEAR off leaves and needles from rooflines, gutters, decks, porches, patios, etc.


  • STORE furniture, cushions, mats, potted plants and decorations.


  • SCREEN and SEAL any vents or openings.


  • RAKE mulch and leaves to at least five feet from the building.


  • TRIM shrubs and trees to create at least a five foot wood-free zone around the building.


  • REMOVE anything around the building within 30 ft. that could burn.


  • CLOSE all openings to the building if ordered to, even pet doors.

All GIFs are shared from Giphy

The ember threat

Embers (burning pieces of wood or vegetation) are the main cause of residential loss during wildfires. The good news is there are ways to protect your home from embers and surface fires during a wildfire event. Home ignition zones, or HIZ, are three spatial zones to consider when protecting your home.

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Photo © Orin Zebest

Immediate Zone: (0-5 feet from the residence) This is the most important zone to take action. This zone should include non-combustible housing materials and vegetation, like sod and annuals.

Intermediate Zone: (5-30 feet) In this zone, use landscaping to create breaks around your home and decrease the potential of fire transmission. For example, place trees so the canopy is no closer than 10 ft from the building and cluster vegetation with wide breaks in between.

Extended Zone: (30-100 feet) in this zone, tree spacing and species composition are important to consider along with clearing debris and removing ladder fuels. The goal here is to keep fire activity low to the ground and patchy.

For more information on HIZ visit Firewise USA

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Photo © USDA

It is a delightful challenge to both protect my home from wildfire and find ways to creatively, and safely, create habitat through careful planting of natives, selective pruning, and the art of strategic tidying-up.

Please note that some recommendations for minimizing fire risk run contrary to recommendations we make for encouraging habitat at home. It can be challenging to have competing goals for a property, especially when recommendations for meeting those goals might seem at odds with one another. As Project Leader, Rhiannon Crain, and wildfire-prone California resident, notes, It is a delightful challenge to both protect my home from wildfire and find ways to creatively, and safely, create habitat through careful planting of natives, selective pruning, and the art of strategic tidying-up.

Post wildfire Niobrara Valley Preserve, Nebraska. (ALL RIGHTS, ALL USES) PHOTO CREDIT: © Chris Helzer/TNC

Photo © The Nature Conservancy (Chris Helzer)

Wildfires can seem like big contradictions: though they are natural and important, they also are an ever-increasing threat in our landscapes. How we manage our public and private lands is important for wildlife and wildfire preparedness. Everyone has a role to play and together we can make sure communities and ecosystems are more wildfire-resilient, putting us on a path to creating safer and healthier conditions for people and nature.

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