It certainly seems that the wildfire problem is getting worse. Wildfires have ravaged the western states in the past decade, but other areas are also threatened. Florida residents faced one of the worst fire seasons in years this spring. Before that, wildfires in the Plains had burned 1 million acres. Last fall, the Southeast saw unprecedented fire activity — and it’s not just wildlands that are burning. On Nov. 28, 2016, the Chimney Tops 2 Fire roared through Gatlinburg, Tennessee, killing 14 people and damaging or destroying 2,400 buildings. In Alberta, Canada, wildfires have devastated the towns of Slave Lake and Fort McMurray in recent years.
Examining the causes
Increasingly, people have been moving away from urban centers and into natural areas or wildlands. There is an obvious appeal of living close to nature for many. This has created a “wildland-urban interface,” where human habitation meets natural surroundings. Fire has always been a part of nature; in many ways, it’s nature’s way of recycling. Recurrent fires may seem only destructive, but they are followed by regrowth and resurgence. But the wildland-urban interface can be easily crossed by fire and man’s possessions, and even his safety can be threatened. According to the Insurance Institute for Business and Home Safety, “Wildfire is a serious risk in 38 states, threatening about 120 million people and their property.”
Even under the best conditions, urban fire departments would be hard-pressed to protect all homes from an approaching wildfire. The scale is much greater than anything they are prepared for.
There are steps that can be taken to reduce the risk from wildfire damage. This is where the tree care industry gets involved.
The “wildfire equation” has several components. First, you need fuel. This can be trees, shrubs, grasses, material on the ground such as leaves, or even materials below the surface. Technically, there is a distinction between a “ground fire,” which stays at low levels, and fires that jump into the canopy, the extremely destructive “crown fires.”
In terms of flammability, deciduous hardwoods are less prone to burning. Their leaves have high moisture content and fall off when dry. Conifers with their ever-present needle-like leaves and resins are prone to fires at any time. With wildfires typically starting as ground fires, lower fuels are critical and they must be dry. Although surface fuels can dry out quickly under the right conditions, long-term drought conditions precede most major fires.
In some sections of the country, drought is a seasonal occurrence. In the West, summers are dry. The fire season can start in late spring and continue into the fall until the winter wet season starts. Less precipitation in the winter will exasperate the fire situation later in the year. In southern Florida, winter is the dry season. As we have seen this year, if the sporadic rains in winter are lacking, the fire problem becomes acute. In the southern Plains, warmer and drier conditions even in winter can lead to fire activity. In much of the eastern part of the country, precipitation is typically more evenly distributed over the year. But droughts occur on a sporadic basis.
If dry fuels are available, fire ignition is the next concern. Although lightning strikes start some wildfires, man-caused fires are the major problem. Estimates range up to 90 percent of all wildfires are started by man. Often these are debris burns that get out of hand. Arson is also a cause. The other factor is wind. Fires that occur under calm conditions are typically easily controlled. When the winds are up, wildfires move quickly. And movement is far from consistent. Spotting, a new fire starting downwind of the main fire line due to airborne burning debris or embers, causes fires to jump forward. In some situations, spot fires can occur a mile or even more ahead of the main fire. In reality, it’s the “attack from above” that causes much of the fire damage. When conditions are at their worst with wind and dry fuels, wildfires are unstoppable. In the West, topography is also a problem. The rugged terrain and winds cause erratic fire movement, making fire suppression more difficult.
There are two factors that make the wildfire problem worse. Global warming is causing longer, more severe fire seasons. Significant droughts are becoming more frequent. Also, fire suppression efforts have actually increased fire intensity. Wildfires were a part of nature’s cycle and occurred on a frequent basis in most areas. Fires burned until they had no fuel or rain fell. Understory vegetation was regularly burned off. With fire suppression, areas go for years without fires. Fuel loads increase and when wildfires do occur, they are much more intense and damaging.
Tree care specifics
The wildfire problem is so acute in the western U.S. that fire mitigation services are routinely provided by tree care professionals. The goal is to reduce the risk of fire damage to property. In some locales, insurance companies actually require such actions to keep your property insured.
The key to fire mitigation is to provide a defensible space around the house (or other structure). A defensible space means that firefighters could safely occupy this area while battling the blaze. It will also greatly reduce (but not eliminate) the risk of a wildfire engulfing your home.
A three-zone defensive perimeter is recommended. Zone 1 extends from the house to 30 feet away. Trees should either be removed or, if kept, at least 5 feet from the home and pruned to a height of 10 feet (especially conifers). Any limbs hanging over the house and all flammable or dead vegetation should be removed.
Zone 2 extends at least 100 feet away from the house. Natural vegetation is permissible with some alterations. Dead or dying branches or trees should be removed. Branches should be trimmed below 6 or even 10 feet. Understory vegetation should also be thinned or totally removed. The goal would be to stop or at least slow any approaching fire along the ground and/or keep it from crowning.
Zone 3 extends at least 200 feet from the house and will eventually blend into the natural vegetative cover. Even here, some of the same steps used in Zone 2 could be done to reduce fire risk, especially thinning of vegetation. Of course, all debris produced in these zones should be removed.
Two excellent sources of information are, “The Basics of Defensible Space and the Home Ignition Zone” by the National Fire Protection Association and “Protecting Your Home From Wildfire: Creating Wildfire-Defensible Zones,” a Colorado State University-Forest Service Guide. These provide detailed instructions for homeowners or those who offer such services to homeowners.
Although wildfire mitigation is a service primarily in the western part of the country, as noted above, wildfires can occur in many other areas. Mitigation services could be provided in many locations.
After a wildfire, tree care professionals may be asked to assess fire damage. They may be asked to determine if fire-damaged trees can be saved. They may also be involved in the cleanup and restoration efforts. This would include the removal of badly-damaged or dead trees and the planting and caring for new trees and/or vegetation.