Forest Thinning Will Increase Wildfire Risk
– by Charles Thomas, The Oregonian
As fires again rage across the West, senators from John McCain, R-Ariz., to Ron Wyden, D-Ore., echo the refrain “thin the forests” to prevent wildfires. Unfortunately, most of the advocated thinning will actually stoke the wildfires of the future rather than lessen their occurrence and impacts.
Thinning prescriptions proposed in Wyden’s O&C legislation, designed by eminent foresters Jerry Franklin and Norm Johnson, will stimulate hotter, faster-growing wildfires that are more hazardous to fight. These prescriptions drastically thin forest canopies through timber sales designed primarily to generate timber volume, often leaving the slash and smaller shrubs and trees for non-commercial fire hazard reduction projects that are usually underfunded, unable to match the pace of canopy thinning projects and clear-cuts across the landscape.
Thinning forest canopies opens the stands to more sunlight, which encourages growth of fine fuels, including shrubs, small trees and grasses. Penetration of sunlight and dry summer winds effectively increases the active fire season by drying this new growth and leftover logging slash much faster than in adjacent unlogged forest stands, where greater canopy closure with tall shade columns retains moisture in soils and vegetation.
Active fire season begins weeks earlier in thinned forests and lasts weeks later, drastically increasing the time span during which dry forest conditions contribute to rapid fire spread. These dry, thinned forests often burn hotter and more erratically than unthinned stands, even causing retreat of firefighters when conditions become too dangerous to maintain fire lines.
Even worse than canopy thinning is clear-cutting, prevalent on private industrial forestlands, which often creates dense brush fields of fire-prone vegetation. Where reforestation is successful, dense plantations overstocked with young trees grow into future fire-bombs of fine fuels with no natural resilience to wildfire.
Examinations of forest fires, particularly in the drier regions of southern and eastern Oregon, reveal where young stands of dense brush and small trees, often choked with untreated logging slash, explode into erratic fires, forcing fire crews off the lines for their own safety. Often these fires lie down and under-burn when they reach residual stands of older forests with closed canopies and a greater level of moisture retention, providing safer zones for fire fighters.
Clear-cutting is widely proposed in both the Senate and House versions of O&C legislation. When added to the dominant practice of clear-cutting on private timberlands, Oregon is being stoked for massive fires beyond anything experienced historically. Canopy thinning is icing on the cake — baked by replacing older forests naturally resistant to wildfires with degraded forests and plantations poised to become conflagrations of the future.
Oregon needs ethical approaches to the onset of climate change, which threatens increased forest fires from higher temperatures and extended fire seasons. It is unethical to place Oregon’s rural communities and brave firefighters at risk to garner higher profits for the timber industry. An ethical approach would be to focus on understory and plantation thinning to reduce fire hazards, especially along roads and around rural communities, while retaining moisture conserving canopy closure in older stands naturally resistant to wildfire.
Charles Thomas, of Jacksonville, has a master’s degree in environmental education and has worked for 40 years in several capacities in the forests of southwest Oregon.