ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

~ 4) Old-growth units should not be isolated with vast stretches of clearcuts or
short rotation stands separating them. Ideally, old-growth units of 50-100 acres
(20 to 40 ha) should be connected with forest corridors at least 300 ft (91 m) wide.
In many cases corridors could follow creeks, also achieving protection of aquatic eco-
systems and providing travel lanes and escape cover for other wildlife.
5) High stumps support carpenter ant colonies and provide feeding sites for wood-
peckers. Wherever carpenter ant activity is identified in a cutting unit, a 0.1 acre
(0.04 ha) circular area of high stumps could be left around that point if provision
of woodpecker food is an objective.
6) Thinning can be detrimental to hole-nesting birds when feeding sites on and
near the ground are covered by cut trees and branches. Thinned material and residues
should not be piled so as to cover log feeding sites.
7) The relevance of the concept of bird species diversity has been appropriately
questioned in relation to resource management objectives (Wiens 1978). Diversity per
se is a measure insensitive to which species are present. The species that require
large territories (e.g., raptors or Pileated Woodpeckers) may receive little attention
if emphasis is on high bird species diversity, particularly over small units of land-
scape. However, basic habitat diversity over large forest areas, is an essential
element of consideration for resource managers. Certain components of the original
diverse forests which existed in northwestern Montana are being greatly reduced as
a result of current timber harvesting practices. Original stands of old-growth west-
ern larch, for example, have been reduced by nearly one half since timber cutting
began. Where old growth is el iminated over vast areas, many birds dependent on it may
be extirpated. The importance of perpetuating habitat diversity is therefore a rele-
vant and necessary concern of forest resource managers. Old-growth stands in national
parks, wilderness, and natural areas are not sufficient in themselves because they
could increasingly take on the character of islands surrounded by great seas of
short-rotation stands. These "islands," particularly the smaller ones, will probably
be incapable of sustaining the same richness of bird species diversity that is present
in larger stands. Therefore, on commercial forests the perpetuation of an old-growth
component needs to be incorporated as a legitimate goal of the management process.
Based on studies at the CEF and nearby areas, we suggest that about 10% of forest
planning units in the western larch/Douglas-fir forests be managed as old growth.
This can be accomplished by long rotations, partial cutting to encourage larch (but
retaining a high basal area in large-diameter classes), not re-entering she1 terwood or
seed tree cuts, or other methods that can be devised by skillful interdisciplinary
teams.
8) The ecological relationships between birds and the forest may never be comple-
tely understood, but recognition of the ecosystem concept requires that hol e-nesting
birds and their habitats be perpetuated. If for no other reason they should be per-
petuated simply because (to paraphrase Aldo Leopald) the first precaution in intelli-
gent management is to keep every cog and wheel. Sufficient data are now available to
enable foresters to prepare timber harvesting and residue management plans that are
more responsive to the needs of cavity-nesting birds and other members of the wild-
life community.
AC KMOWLEDGMENTS
Richard Blodnick, Brian Cooper, and Barbara Von Gunten served as student research
assistants and gathered much of the field data. U.S. Forest Service employees Carl
Fie1 dl er, Ray Shearer, Jack Schmidt provided assistance at various stages of the
study. Roland Barger, program manager for the residues util ization program, was es-
pecially helpful in his continuing support of the study. Curtis Halvorson, U.S. Fish
and Wildlife Service, and Sidney Frissel 1 , School of Forestry, University of Montana,