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Mitigation Monday – Fuel Types and How They Affect a Wildfire

Last Monday, we talked about a home’s ignition zone. But it’s also important to understand the different type of fuel sources that exist around your home, and how differently a forest fire will react with these fuel types. Fuels are broken down into three different categories: Surface Fuels, Vertical or Ladder Fuels, and Crown Fuels.

Surface Fuels

Surface Fuels consist of Grasses, Needles, Leaves, Logs, Branches, Slash, or anything else that is low to the ground. Grass is the most pervasive source of surface fuel, will ignite quickly and spread rapidly. Because of this, it will also burn out quite quickly. Needles and leaves can catch quickly, and are quick to spread, causing damage and igniting anything nearby. Larger surface fuels like logs and slash are much larger sources of fuel, generating more heat and can be extremely dangerous to nearby structures. It’s important to keep grass mowed, and other surface fuels cleaned up and away from your home to slow a fire’s approach.

Ladder Fuels

Ladder fuels consist of smaller trees, brush, shrubs, and anything that allows a fire to leave the ground and burn upwards towards crown fuels. While these fuels can be potentially hazardous, they are easy to mitigate. Clear areas under trees and prune dead branches near the ground. Space brush and small tree away from each other – at least six to ten feet – to help keep fire from rising into the air.

Crown Fuels

Crown – or aerial – fuels consist of the upper portion of tree canopies. Crown fires are intense, move rapidly, and can burn a large area. When a fire is in the air, it can also throw sparks well in front of itself, causing spot fires to ignite, even miles away from its original source. Thinning trees and removing as much surface and ladder fuel from around the base of the remaining trees is the best way to mitigate crown fires.

Fire mitigation takes constant effort, but knowing how fires are fueled can help you get ahead of any potential fire danger and protect your property. As always, the Colorado State Forest Service has provided a guide to help homeowners protect their homes from wildfires: https://csfs.colostate.edu/media/sites/22/2021/04/2021_CSFS_HIZGuide_Web.pdf