Regional Patterns of Dead Wood in Forested Habitats of Oregon and Washington

We describe regional patterns of variation in dead wood across 20 million ha of upland forests of all ownerships in Oregon and Washington, based on an analysis of data on snags and down wood collected on over 16,000 field plots. Current patterns of dead wood are highly variable and complex. The strongest differences were among nine habitats that reflect strong regional gradients in physical environment and ecosystem processes. Mean snag density was lowest in the drier habitats east of the Cascade crest and greatest at higher elevations, ranging from 0.8/ha to 37.2/ha. The mean volume of down wood ranged from 7.4 m/ha in western juniper woodland to 183.3 m/ha in westside conifer-hardwood forest. Differences in dead wood were more pronounced among habitats west of the Cascade crest. Dead wood abundance generally increased with successional development. Large snags were more than twice as dense within wilderness areas than outside wilderness, whereas large down wood was more abundant outside wilderness. Dead wood on plots was non-normally distributed and skewed to the right. Information on regional patterns of variation in dead wood is being incorporated into the DecAID model, which will help guide managers in considering dead wood and processes of decomposition in forest management. The regional summaries of dead wood also can be used to evaluate forest practice regulations and incentive programs for non-Federal lands, and to assess wildlife habitat suitability, ecosystem health, and carbon stores at state, regional, and national levels.