Summary
Wind River Experimental Forest, WA
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In this
report we present data on the decomposition rates of seventeen tree
species in eight locations in western U.S.A., (five locations in Oregon,
one in California, one in Colorado, and one in Washington).
One to five species were sampled at each site. In addition, six of the tree species were sampled at two
different locations. At four
of the locations we employed the chronosequence method, dating fallen
trees from fall scars, from living stumps, and known ages of logging and
thinning slash. At three of
the sites, fresh logs were placed out and resampled at various times using
a time series method. At
four
of the sites we used the decomposition vector method, resampling logs of
various decay classes after a period of 4 to 20 years.
Density and volume losses of the boles were examined.
The decomposition rate of the seventeen species varied greatly, with
values ranging from 0.011 to 0.083 year-1
(i.e., the proportion lost each year).
The one deciduous tree species examined (Alnus rubra)
decomposed slightly faster (0.055-0.083 year-1)
than Abies, the fastest decomposing softwood genus (0.023-0.051
year-1). Within the softwoods, the range in decomposition rate
was from 0.007 year-1 to 0.051 year-1.
These results are hypothesized to be caused in part by the
difference in heartwood decay resistance and correspond to wood products
durability ratings. Comparison
of species and similar species along temperature and moisture gradients
indicates that these variables are interacting in complex ways.
While there is an increase in decomposition rate with increasing
temperature, this appears to be offset by increases in moisture at the
warmest sites examined. |
