PORTLAND, OR. April 9, 2007. A new study on the effects of timber harvest following wildfire shows that the potential for a recently burned forest to reburn can be high with or without logging. Recently published in the journal, Forest Ecology and Management, the study demonstrates that the likelihood of a severe reburn is affected by the timing not just the amount of fuel accumulation after fire.
The study examines fuel accumulation with and without logging after a large wildfire in the Blue Mountains of northeast Oregon. Three treatments were examined: commercial logging that removed only dead trees with value for wood products, commercial logging plus thinning that removed all dead trees larger than 4 inches in diameter, and unlogged sites.
The year after logging (3 years after the fire), sites that were logged and thinned had four times more fine fuels on the ground, as a result of logging residue, compared to unlogged sites. Those same sites also had fewer snags which provide habitat for woodpeckers, owls, and other animals that nest in tree cavities and contribute to large woody debris on the ground. However, logging activity caused no change in the litter or duff, the upper soil organic layers that also affect how a fire burns. The study was led by James McIver of Oregon State University and Roger Ottmar of the Pacific Northwest Research Station, U.S. Forest Service.
The investigators used a computer model to project how fuels and fire hazard would change over time. "Long-term research and monitoring are not always possible," says McIver. "Although we would rather have the long-term data, using a model allows us to estimate some of the future ecological effects."
The computer simulation showed that the difference in surface fuels between logged and unlogged units would persist for about 15 years. The simulation also showed that if a fire did start during this time, it would likely kill most young trees as the
Contact: Sherri Richardson Dodge
USDA Forest Service, Pacific Northwest Research Station