Resource Science: Impacts of forest and range fires

(Editor’s note: This article was updated to adjust figures.)

Forest and range fires (also called wildfires or wildland fires) destroy property, timber, grass, wildlife habitat, affect water quality with increased runoff and soil erosion, and emit large amounts of greenhouse gases (GHG). The effects of fires are not always negative, and controlled prescribed fires can prevent large destructive fires by removing fuels. Fire can also improve forest and range conditions by controlling invasive weeds and conifer encroachment, enhancing forage quality increasing plant diversity and improving wildlife habitat.

However, in many cases, preventing and controlling forest and range fires is necessary to prevent large scale destruction and the loss of timber value. Between 2001 and 2021, 46 million to 61 million acres of timber in forests burned worldwide. This timber would be worth about $45-77 billion at the 2021 average price of $0.27/board foot (see the References at wlj.net). Local estimates for the northwest U.S. are about 1,000 to 2,000 board feet (1 to 2 mbf) per acre and $0.30 to $0.40 per board foot of timber. Loss of timber on an acre in the northwest can be estimated as a loss of about $300-800 per acre.

The U.S. Forest Service reports that in the U.S., wildfires and prescribed fires are a significant source of GHG (e.g., carbon dioxide, or CO2, and methane, or CH4) and carbon particle emissions. Exposure to smoke is also a hazard to public health and firefighters (see the References). GHG are thought to be the primary cause of climate change. I’ve written before about the amounts of CO2 emitted from forest fires (WLJ March 28, 2025) and how timber harvest can prevent forests from burning and lock up CO2 in wood products and regenerating trees. Locking up CO2 is called sequestering in climate change research. Forests currently sequester 12.4% of the U.S. GHG emissions and good forest management can substantially increase this.

My calculations indicated that about 225 (200 to 250) tons of CO2 per acre of forest can be locked up in harvested wood products. Another 123 tons of CO2 per acre can be locked up in new tree regeneration after about 60 years. This indicates that timber harvest followed by regenerating trees can lock up about 350 (325 to 375) tons of CO2 per acre. The amount of CO2 per acre will vary among locations, tree species and age, and other factors, but it’s clear that lots of CO2 can be locked up in wood products and tree regeneration.

Consider estimates on a larger scale. The Department of the Interior (DOI) keeps track of fires in the U.S. In the 42 years from 1983 to 2024, there was a total of 2.9 million fires, with an average of about 70,000 fires per year in the U.S. These fires include 217 million* total acres burned with an average of 5.2 million acres burned per year. (*Updated on Nov. 13 to 217 million acres from the originally noted 2.2 million acres).

The DOI report doesn’t specify how much of the 5 million acres burned per year area is forest, so I’ll do some rough calculations. Let’s say half of the 5 million acres is forest: 2.5 million acres of trees/year burned or killed and decayed. Using my estimate of 225 tons CO2/acre in timber: 225 tons/acre multiplied by 2.5 million acres = 563 million tons of CO2/year emitted from fires nationwide. It’s important to acknowledge that this is a gross estimate because of my assumption that half of burned area is forest and the amount of CO2/acre will depend on many factors.

Regardless, forest fires release a large amount of CO2 and other GHG. Total CO2 emissions in the U.S. in 2024 from residential, commercial, industry, transportation and electric power (not fires) was 5.3 billion tons. A total of 563 million tons emitted by fires divided by 5.3 billion tons of human emissions equals 0.11. This means that forest fires emitted 11% as much CO2 as human emissions in the U.S. in 2024. Limiting emissions from fires should be a priority for climate change mitigation.

Why is this issue important? Preventing the loss of human life, property, valuable timber and other negative effects of fires is the most obvious reason. But the potential to harvest timber while at the same time locking up substantial amounts of GHG are also obvious and complementary management objectives.

Climate change and reducing GHG continues to be a big environmental issue, as do environmental opposition and lawsuits to stop timber harvest, particularly on Forest Service and Bureau of Land Management lands. Using timber harvest to improve forest management and to lock up CO2 should not be opposed by environmentalists. It should be endorsed as a way to better manage forests and help mitigate climate change. — Matt Cronin, WLJ columnist

(Matt Cronin is a biologist with Northwest Biology and Forestry Company LLC in Bozeman, MT, and a teaching professor at Montana State University. He may be contacted at croninm@aol.com.)