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.  

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