Peck,
J.E. 1997c. Commercial Moss Harvest Impacts:
A retrospective study. Report
to the Tillamook Resource Area, Salem District Bureau of Land Management,
Tillamook, OR.
The impacts of
commercial moss harvest on bryophyte communities has only recently begun to be
documented. This represents the first attempt to compare sites known to
have been commercially harvested with those believed to be undisturbed for at
least 20 years. Seven pairs of 1/3 acre plots in the Tillamook Resource
Area were surveyed for the most common and abundant epiphytic bryophytes.
Plots were compared on the basis of average cover and total species richness
across all available substrates for trees and shrubs (by species) , logs, and
the forest floor. No differences among treatments were detected for cover,
species richness, or species composition for the most common and abundant
epiphytic bryophytes on any substrate. The failure to detect differences
may be due to a) the general nature of these surveys, which are not sensitive to
rare species and/or b) the likelihood of previous disturbance in the
"unharvested" plots. Although "unharvested" plots were
selected on the basis of our best understanding of what these areas should look
like, the absence of any sites that are truly known to be undisturbed leaves us
without a standard for comparison. Application of these results to other
areas of the Resource Area is not recommended, given site selection criteria,
the focus on only common and abundant species, and the unknown disturbance
histories of these plots.