December 21, 2000
Helena Independent Record
P.O. Box 4249
Helena, MT 59604
Editor:
In a recent �Your Turn� editorial in the IR, longtime
forester Jack Mahon wrote �fish biologists and environmental elitists have not
been honest with the public concerning the extent of adverse impact on the fish
resources from timber harvest�. In support of this assertion, Mr. Mahon cites
recent newspaper articles in which a fisheries biologist states that the impacts
of fires may be negative in the short term but beneficial in the long term. The
article discussed potential impacts of fire and concluded that some of the
impacts such as direct fish-kills due to fire, increased sedimentation and
potential debris flows could impact fisheries in the next few years, but
increases in trees falling into streams and the mosaic left after fires will be
a benefit in the long term. At the same time, fisheries biologists are concerned
about the impact of sediment from timber sales on native bull and cutthroat
trout. Mr. Mahon wonders how sediment from timber harvest can be bad, yet
sediment from fires and severe floods (such as the 1996 Yellowstone River
flooding) is not.
Mr. Mahon raises a good question that deserves response. In
short, roads have traditionally been necessary for timber harvest but not for
fires and floods. Typically, natural events that cause high sediment loads are
short term in nature but often the extensive road systems used for historic
timber harvest are not. The roads that accompany timber harvest can be a chronic
source of sediment during spring runoff as well as during summer rainstorms.
Sediment carried by a stream during a flood is transported by the high
streamflows when streams naturally convey sediments. Typically, these sediment
loads which last for a short time, or just a year or two as a result of a fire,
will be deposited in locations that are advantageous to normal stream
development such as floodplains and stream margins. As the sources of this
sediment heal, the amount of sediment entering the stream diminishes to baseline
levels with time if the watershed is in good condition. Sediment from unstable
or improperly drained roads enters a stream during any season for many years, is
not transported easily during low streamflows and can end up in a location such
as a pool bottom or riffle where it causes problems for trout and aquatic
insects, their primary food source.
Another difference between timber harvest and fires or
floods is the effect on the trees along the stream. Fires typically leave most
of the large trees along a stream, many of which will eventually fall in,
providing hiding cover and creating pools for trout. Floods which cause
streambank erosion may also cause trees to fall into the stream. Some historic
and even present day timber harvests remove many of these streamside trees. The
lack of trees falling into streams represents the loss of one of the most
important habitats for trout. The importance of trees to streams and fish is
widely recognized by ecologists, hydrologists and fisheries biologists, and
it�s one of the reasons some logging prescriptions call for leaving most
standing trees in riparian areas.
Numerous published articles and observations by fisheries biologists describe the rapid
recovery of fisheries from acute events such as fire and floods. There are also numerous published articles describing the negative impacts of sediment, usually from roads or logging-related landslides, and the loss of �large woody debris� in streams. Neither fisheries biologist cited by Mr. Mahon criticized today�s forestry practices, and I think we would all agree that most present day forestry practices have less negative impacts than in the past. Fisheries biologists commonly work with foresters on timber sale planning and both have benefited from this relationship. To conclude that fisheries biologists have not been honest about the effects of various activities is erroneous.
As a professional society representing a variety of aquatic scientists, we encourage fisheries biologists to interact with foresters on questions about forest practices. Our experience has been that professional foresters are interested and receptive to our input about fisheries issues. We look forward to continuing that positive relationship.
Sincerely,
Michael Enk, President
Montana Chapter, American Fisheries Society
P.O. Box 1408
Great Falls, MT 59403
791-7729