Effects of Slash Burning in Overmature Stands of the Douglas-Fir Region

Abstract

Following clearcutting of old-growth coniferous forests in western Washington and Oregon, pairs of burned and unburned plots were established to determine the effects of normal fall slash burning. Fires consumed nearly all fine fuel, left nearly all logs, and severely burned less than 6 percent of the soil surface. Five years after burning, the estimated rating of fire spread on the burned plots was 27 percent of that on the unburned, and estimated resistance to control was 67 percent. Difference in rate of spread ended at 16 years; difference in resistance to control ended at 12 years. Burning changed species composition of brush and herbage, reduced brush cover for a few years except where Ceanothus sp. invaded, but did not affect total herbaceous cover. Burning did not affect ultimate quantity of natural stocking with commercial conifers that became estab- lished after logging. Forest Sci. 16:258-270. THE ESTABLISHED management system of clearcutting the tall, dense, overmature forests of the Douglas-fir region of western Oregon and Washington usually leaves great quantities of debris after all mer- chantable wood is removed. Limbs up to l0 inches through, masses of small limbs and needles, thick slabs of bark, short chunks of broken trunks, long logs riddled by heart rot, shattered remains of large snags, and moss-coated windfalls of the past 50 years cover most of the ground