Commercial Logging for Wildfire Prevention: 
Facts vs. Fantasies
by Timothy Ingalsbee, Ph.D.
Director, Western Fire Ecology Center
The notion that commercial logging can prevent wildfires has its fervent believers and loud proponents, but this belief does not match up with the scientific evidence or history of federal management practices. In fact, it is widely recognized that past commercial logging, road-building, livestock grazing, and aggressive firefighting are the sources for "forest health" problems such as increased insect infestations, disease outbreaks, and severe wildfires. How can the sources of these problems also be their solution? This internal contradiction needs more than Smokey Bear myths to be resolved. It is time for Congress to heed the facts, not fantasies, and develop forest management policies based on science, not politics.

FACT: Commercial logging removes the least flammable portion of trees--their main stems or "trunks," while leaving behind their most flammable portions--their needles and limbs, directly on the ground. Untreated logging slash can adversely affect fire behavior for up to 30 years following the logging operations.

FACT: Commercial logging reduces the "overstory" tree canopy which moderates the "microclimate" of the forest floor. This reduction of the tree canopy exposes the forest floor to increased sun and wind, causing increased surface temperatures and decreased relative humidity. This in turn causes surface fuels to be hotter and drier, resulting in faster rates of fire spread, greater flame lengths and fireline intensities, and more erratic shifts in the speed and direction of fires.

FACT: Small-diameter surface fuels are the primary carriers of fire. Current fire spread models such as the BEHAVE program do not even consider fuels greater than three inches (3) in diameter because it is mainly the fine-sized surface fuels that allows fire spread. Commercial logging operations remove large-diameter fuels which are naturally fire resistant, and leave behind an increased amount of fire-prone small-diameter fuels.

FACT: Timber plantations are comprised of densely-stocked, even-aged stands of young conifers that are extremely flammable and vulnerable to catastrophic fire effects. When plantations burn they normally result in 100% mortality of trees, yet have no native seed sources to naturally regenerate stands. Thus, burned plantations require expensive and repeated management inputs to achieve successful reforestation.

FACT: Commercial logging spreads invasive weeds and stimulates the growth of "chaparral" brush which are much more flammable than the original forest cover. Once the commodity timber outputs have been removed, federal agencies have no economic incentives to manage the vegetation that colonizes sites disturbed by logging operations; thus, fires will continue to burn through logged areas.

FACT: Watersheds that have experienced extensive logging and road-building also experience greater fire severity than unlogged and unroaded watersheds.


"Timber harvest, through its effects on forest structure, local microclimate, and fuels accumulation, has increased fire severity more than any other recent human activity".
--Sierra Nevada Ecosystem Project, 1996. Final Report to Congress

"Logged areas generally showed a strong association with increased rate of spread and flame length, thereby suggesting that tree harvesting could affect the potential fire behavior within landscapes…In general, rate of spread and flame length were positively correlated with the proportion of area logged in the sample watersheds."
--Historical and Current Forest Landscapes in Eastern Oregon and Washington. Part II: Linking Vegetation Characteristics to Potential Fire Behavior and Related Smoke Production (PNW-GTR-355)

"As a by-product of clearcutting, thinning, and other tree-removal activities, activity fuels create both short- and long-term fire hazards to ecosystems. The potential rate of spread and intensity of fires associated with recently cut logging residues is high, especially the first year or two as the material decays. High fire-behavior hazards associated with the residues can extend, however, for many years depending on the tree. Even though these hazards diminish, their influence on fire behavior can linger for up to 30 years in the dry forest ecosystems of eastern Washington and Oregon."
--Historical and Current Forest Landscapes in Eastern Oregon and Washington. Part II: Linking Vegetation Characteristics to Potential Fire Behavior and Related Smoke Production (PNW-GTR-355)

"It appears significant that many large fires in the western United States have burned almost exclusively in slash. Some of these fires have stopped when they reached uncut timber; none has come to attention that started in green timber and stopped when it reached a slash area."
--G.R. Fahnestock, 1968. "Fire hazard from pre- commercially thinning ponderosa pine." U.S. Forest Service

"Fire severity has generally increased and fire frequency has generally decreased over the last 200 years. The primary causative factors behind fire regime changes are effective fire prevention and suppression strategies, selection and regeneration cutting, domestic livestock grazing, and the introduction of exotic plants."
--Integrated Scientific Assessment for Ecosystem Management in the Interior Columbia Basin (PNW-GTR-382)

"The high rate of human-caused fires has generally been associated with high recreational use in areas of higher road densities."
--An Assessment of Ecosystem Components in the Interior Columbia Basin and Portions of the Klamath and Great Basins--Volume II (PNW-GTR-405)

"Mechanically removing fuels (through commercial timber harvesting and other means) can also have adverse effects on wildlife habitat and water quality in many areas. Officials told GAO that, because of these effects, a large-scale expansion of commercial timber harvesting alone for removing materials would not be feasible. However, because the Forest Service relies on the timber program for funding many of its other activities, including reducing fuels, it has often used this program to address the wildfire problem. The difficulty with such an approach, however, is that the lands with commercially valuable timber are often not those with the greatest wildfire hazards."
--GAO, "Western National Forests: A Cohesive Strategy is Needed to Address Catastrophic Wildfire Threats" (GAO/RCED-99-65)