Duff consumption by fire was studied on 15 cable-yarded clearcut units in western Oregon and western Washington. Equations are presented that predict duff consumption (in depth reduction and weight loss) from loading, consumption, and moisture of large fuels, and days since significant precipitation. When more than 25 days elapsed since 1.3 cm rainfall, the effect of large fuel loading on duff consumption diminished. Duff consumption was dependent on the diameter reduction of large fuels when there had been no rain for at least 25 days. The results indicated that duff consumption can be reduced by removing large fuel before the burn, scheduling the burn under moist conditions, or both. Methods are demonstrated to prescribe the proper level of fuel removal and moisture regime at time of burn to achieve a given level of duff consumption.
Little, Susan N.; Ottmar, Roger D.; Ohmann, Janet L. 1986. Predicting duff consumption from prescribed burns on conifer clearcuts in western Oregon and western Washington. Res. Pap. PNW-RP-362. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 29 p