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Forests in northwest Oregon grow quickly making fuels reduction on your forested property an ongoing process. Regular maintenance activities will be necessary to keep your wildfire risk lowered.
Fire requires three ingredients: fuel + heat + oxygen. These components are required for a fire to occur. If any are removed, then the fire goes out. Fuel is the only component we can reduce and manage.
Most homes burn when embers moving ahead of the flames land on debris or flammable materials around your home. By managing the fuel or vegetation around your structures, you can reduce the threat of wildfires and allow firefighters to more safely and effectively defend your property.
Creating defensible space
The Home Ignition Zone (HIZ) includes any structures and their immediate surroundings, out to a distance of 100 feet, or 200 feet on steeper slopes. The work you do within the Home Ignition Zone is called creating defensible space, and it plays an important role in reducing the risk of losing your home to wildfire.
Maintaining a defensible space is an ongoing activity. Plants grow back, and flammable vegetation needs to be routinely removed and disposed of properly. Each year, evaluate your defensible space in the winter and spring leading up to fire season and make the necessary recommended actions.
The HIZ is divided into three sub-zones:
- Immediate zone: structure to first 5 feet
- Intermediate zone: 5 to 30 feet from each structure
- Extended zone: 30 to 100 feet from each structure, or up to 200 feet on steep slopes
Immediate zone: 0-5 feet from each structure
Winter
- Prune branches within 10 feet of the home, outbuildings and attachments, including chimneys, decks and garages.
- Remove shrubs and trees growing directly under eaves.
Spring
- Remove dead plant material, including leaves, needles, twigs and firewood piles.
- Clean roof and gutters of debris. Remove material under decks and other overhangs.
- This zone should be nearly free from flammable material. Recommended landscaping in this zone is concrete, rock, clover or succulent ground cover.
Intermediate zone: 5-30 feet from each structure
Winter
- Favor low-growing herbaceous vegetation. Maintain small islands of vegetation in this zone so the fire cannot spread easily.
- Prune branches of mature trees six to 10 feet from the ground; do not exceed one-third total tree height.
- Remove all dead and dying trees and shrubs.
Spring
- Mow grass to a maximum of four inches in height.
- Remove highly flammable brush and weed species that have re-grown.
- Clear vegetation around propane tanks.
- Remove any down wood and vegetation under trees. Prune dead branches.
Extended zone: 30-200 feet from each structure
Winter
- Thin out overly dense patches of trees and shrubs. Retain large, healthy conifer trees and deciduous trees.
- Remove, trim, or prune ladder fuels, which are vegetation under trees.
- Maintain shaded fuel breaks, which are areas with heavy thinning and ladder fuels have been removed.
Spring
- Remove any vegetation blocking visibility to your home address and other emergency signage, such as emergency routes or water access.
- Remove encroaching vegetation from the roadway. Keep turnouts clear.
- Remove invasive species, large build-up of ground litter, debris and down wood.
Extending your protection
Before you get started, be aware of how the landscape affects your home’s risk. Manage vegetation more often and longer distances (up to 200 feet) on south slopes, in the line of prevailing east winds and at the tops of hills because these areas are prone to drier conditions.
Prevention is key
Remove overgrown vegetation to create islands of fire-resistant plants with space between the shrubs and the trees. The vegetation's structure, density and location impact home survivability most.
Minimize risk by reducing unwanted vegetation by planting and maintaining native fire-resistant vegetation.
- Fire-Resistant Plants for Home Landscapes (PNW 590)
- Reducing Fire Risk on Your Forest Property (PNW 618)
Free home assessments
During a fire, embers are the primary cause of structures burning. Understand your homes ignition potential by getting a home assessment.
- If you live in Lane County, the Oregon Department of Forestry, Western Lane District Office will conduct free home assessments and provide you with guidance on how to protect your home and property from wildfires. Phone: (541) 935-2283.
- Home assessments can also be scheduled through the Oregon State Fire Marshal's office.
- Use the Oregon Forest Industry Directory to find a service provider for technical assistance.
Decrease ladder fuels
Understory vegetation, such as small trees, low branches, grasses and brush, can act like ladder rungs — carrying fire from the ground into treetops, which are also called canopy or crowns. By pruning low branches, removing small trees and clearing brush, you can disconnect fire’s pathway into tree canopies. Ladder fuel removal also prevents surface fires from burning too hot, which can damage or kill the trees you want to keep.
Community resources
- Oregon State University, Extension Fire Program
- Oregon Department of Forestry, Fire Prevention Program
Tools for accomplishing your maintenance plan
Thinning
Thinning removes the smaller, dead and dying trees to decrease their density. Larger, vigorous trees have thick bark, taller buds, and deeper roots, increasing their fire resistance. Favor deciduous trees such as the Willamette Valley ponderosa pine and Douglas-fir, as they are the most fire-resistant.
Mechanical or manual treatments
Mechanical (mow, masticate, chip, trim or chop) and/or manual treatments (cut, dig, prune or pull) remove unwanted or overgrown vegetation to increase the space between woody shrubs and trees, as well as reduce ladder fuels by eliminating the vegetation that connects the understory plants to the overstory tree canopy.
Pruning
Pruning removes tree limbs six feet from the ground. Do not exceed one-third the total tree height. Small trees can be removed or pruned every five years until minimum pruning height is reached. Trim dead material from shrubs. Remove shrubs from the understory of your trees or trim to one-third the height of the lowest branches.
Chemical treatments
Chemical treatments are the removal of unwanted vegetation using EPA-approved herbicides. Chemical applications can take the form of broadcast, spot or individual treatment.
Biological treatments
Biological treatments use livestock grazing to reduce unwanted vegetation. Careful management of the frequency, timing, duration and distribution, as well as the number of livestock, is necessary to reach the desired objectives and minimize overgrazing impacts.
Prescribed fire
Prescribed fire reduces the amount of dead wood on the ground and ladder fuels that connect the ground to the canopy. Prescribed fire can be accomplished through pile burning, biochar creation, broadcast and understory burning.
Waste material
Waste material produced by these activities can be hauled away, composted beyond the Home Ignition Zone, piled and burned, burned for biochar or chipped. Small logs can be repurposed and used as fence posts, building material or firewood elsewhere on the property.
Outdoor debris burning safety tips
Burning backyard piles is the leading cause of human-caused wildfires. Please act responsibly and do your part to prevent wildfires!
- DO NOT BURN during fire season.
- Contact your local ODF or rural fire protection district before burning.
- Fires can spread anytime, but late fall and winter have the lowest risk. Always check for safe burning conditions: high humidity, mild wind, low temperatures and minimal fuels.
- Cover piles with polyethylene to keep the material dry.
- Prevent it from escaping: Maintain 10 feet of bare soil around the pile, a water supply and a shovel.
- Burn yard debris only. Keep debris piles small and add more as it burns down.
- Stay with the fire until it is DEAD OUT.
Managing invasive weeds
Invasive weeds have a large impact on forest health and can increase fire danger because many of them are highly flammable and tend to grow densely to out compete our native vegetation. Two of the most common invaders are scotch broom and blackberry. Invasive species should be removed from the site and replaced with native plants to prevent invasive regrowth. Learn more about invasive species management.
Scotch broom (Cytisus scoparius) is a woody shrub with yellow flowers that establishes quickly and in thickets on disturbed sites. Prevent by cleaning equipment. Hand-pull small plants. Use lever-wrenching tools to remove large plants. Cut older plants, no longer green at the base, with two inches or greater stem diameter. Triclopyr, imazapyr, aminopyralid, and glyphosate are effective herbicides applied alone or in combination with 2,4-D. Follow up with replanting natives.
Blackberry (Rubus sp.) is a woody shrub with overlapping thorny canes that create thickets and large edible blackberries. Prevent by cleaning equipment. Hand-pull first-year plants. Dig out the root ball of larger plants. Mow several times a year or graze with goats or pigs. Shade out by growing desirable plants over it. Glyphosate, triclopyr, metsulfuron, and 2,4D, are effective alone or in combination with mowing.
When managing invasive species
- Be adaptive. If plants aren’t responding, try another method or modify the timing or your technique.
- Be persistent. Most infestations require control work several times a year and for several years.
- Combine control methods. Integrative pest management involves selecting from a range of possible control methods to match the management of the site. Often control is more effective with multiple methods.
Thanks to Coast Fork Willamette Watershed Council and Oregon Department of Forestry Western Lane District Office for their collaboration on this piece.
