Introduction 
Wind River Experimental Forest, WA
The management of
large dead and down trees has become a recent concern in Western U.S.
forests. In the past a major
objective was to remove and dispose as much material as possible (Harmon
2000), in part for fuel reduction purposes.
However, we now know that dead wood is associated with many
ecological benefits (plant and animal habitat, nutrient and water storage,
soil formation) and that these benefits all vary with the species of log,
environment, and volume of dead wood on a site (Franklin et al. 1987,
Harmon et al. 1986, Triska and Cromack 1980). This creates a dilemma--- does one manage for fuel reduction
or ecological benefits? Are
these mutually exclusive objectives?
Examination of the impact of fuel reduction programs, effects of
fires (which often create a great deal of dead wood), and maintaining dead
wood levels for ecological benefits will require understanding of the
dynamic process controlling the abundance of dead wood.
The key to
understanding and then managing dead wood dynamically is an understanding
of the rate this material decomposes.
Given this information one can plan the silvicultural, fuel
treatment and other practices required to supply the inputs needed to
maintain dead wood at desired levels. Unfortunately decomposition rates have been determined for
very few species. In the
Pacific Northwest, for example, the main species that have been reported
are Douglas-fir and western hemlock (Graham 1982, Grier 1978, Means et al
1985, Sollins et al 1987). In
this report we present preliminary data for 17 species occurring in the
western United States (five locations in Oregon, one in California, one in
Colorado, and one in Washington). Data
come from a range of studies, some of which placed fresh boles out and
have periodically examined them, others that have dated wood in a place to
determine rates of mass loss, and others that represent resampling of logs
representing a range of decay classes.
Despite this range of methods, all the logs had cross-sections
removed, the volume and mass of these cross-sections was determined to
calculate the density of the cross-sections.
In addition to changes in bole density, changes in log volume were
noted, as this can be a significant form of loss from extremely decayed
logs.
