Thursday, August 9, 2007 - 8:40 AM

COS 108-3: After the Biscuit Fire: Does wildfire meet our dead wood goals?

Diane E. White and Patricia A. Martinez. Rogue River-Siskiyou National Forest

In the warm, dry, Mediterranean climate of southwestern Oregon, downed wood densities were historically regulated by fire.  Fire was excluded for about 60 years from the Siskiyou National Forest (Oregon, USA).  This contributed to fuel increases and likely, to the 200,000 hectare Biscuit Fire that occurred on this forest.  Forest managers are interested in reducing downed wood (fuels) to reduce the severity of wildland fire, yet costs are a limitation for the most favored method, prescribed fire.  Scientists want the return of fire to ecosystems to regulate downed wood levels and promote forest health.  Data on changes in downed wood after wildland fire in southwestern Oregon are lacking.  This project compared downed wood densities prior to and one and three years post-fire.  Under high severity conditions, small downed wood was initially reduced, but three years later it had exceeded pre-fire levels by four-fold.  The large downed wood density remained constant; however, three years post-fire, the variation was greatly reduced.  Under low fire severity conditions, small downed wood density decreased and remained low.  Large downed wood density remained constant and the variation was not affected.  Results showed that downed wood dynamics varied by piece-size and by fire severity.  Difficulty in predicting wildland fire severity may lead to unanticipated densities of downed wood.