ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Much of the research investigating environmental effects has been conducted as
closely integrated study series on specific harvesting sites. Sites were selected
to represent dominant timber types, physiography, and stand conditions in the
northern Rocky Mountains. Most of the research reported in this document was
conducted on four primary field study sites. The four sites, and the harvesting,
utilization, and site treatment practices applied, are described below.
The Coram Study Site
The Coram study site is located on Coram Experimental Forest, on the Hungry
Horse District of the Flathead National Forest. The site typifies old-growth
western larch/Douglas-fir stands on steep slopes. Elevations range from 3,900 to
5,300 feet (1188 to 1615 m), and annual precipitation is in the 25 to 35 inch (64 to
89 cm) range. Western larch and Douglas-fir are the predominant tree species,
a1 though sub-a1 pine fir, Engelmann spruce, western hem1 ock, and birch a1 so occurred
in intermixture on the harvested units. Management objectives for the site (and for
similar sites in the northern Rocky Mountains) include:
--protecting esthetic values;
--timely regeneration and stand devel opment ;
--maintaining species diversity, especially in retaining western
larch in the stand;
--avoiding high road densities;
--avoiding adverse biological impacts on the forest ecosystem.
Steep slopes and operating constraints dictated the use of either aerial or
cable yarding systems, capable of relatively long reach (1,000 - 1,200 feet) (305 -
365 m) and at least partial suspension of logs being yarded. In the case of the
Coram study site skyl ine yarding systems were used--a running skyl ine systems where
both up- and down-hill yarding was required, and a live skyline where uphill yarding
alone was adequate.
Treatments imposed on the study site were developed to test the feasibility of
practicing intensive wood utilization under the management objectives and operating
constraints represented. Since the biological effects of timber harvesting are the
combined influence of silvicul tural prescription, uti 1 ization standard, and any
post-harvest site treatment, combinations of the three were tested. Silvicultural
prescriptions or methods included in the field tests were
(1 ) clearcutting--harvesting a1 1 trees included as merchantable
under the designated util ization standard;
(2) she1 terwood cutting--harvesti ng approximately 50 percent of
the merchantable volume, leaving a designated overstory to
he1 p establ ish a new stand.
(3) group selection cutting--clearcutting all trees designated
as merchantable under the utilization standard, from
irregular, randomly spaced 1 - to 2-acre ( .40 to .80 ha)
plots.