Landslides after clearcuts

PHADRUIG phadruig at aol.com
Sat Feb 21 18:15:19 EST 1998


First of all, let me say that I have enjoyed a number of very informative posts
and valuable discussions on this board.  My thanks to all of you who are
responsible.

Regarding the subject of landslides and clearcuts, I would just like to make a
couple of comments.  

I agree that whenever we can learn by our mistakes, we should take steps to
adjust our operations to avoid those mistakes in the future.  However, let's
not lose sight of the fact that forests "are not forever. " 

In the total absence of logging, or any other man-made land clearing, nature
continues to randomly create bare areas within the forest, over the whole range
of forested land.  If bare areas are more susceptible to land slides than
forested areas, then a natural bare area may be just as susceptable as that
which is man made, i.e. a clearcut.  I say "may be" because logging roads and
skid trails may tilt the scales, in which case those are the factors needing
correction, not the creation of the bare areas themselves.

It occurs to me that care in the location and size of clearcuts, and road
routes (as is current practice, but can undoubtedly be improved upon) along
with present fire control practices, can over the long run actually effect a
decrease in land movement as compared to letting nature take its course.  I
realize that this flies in the face of current environmental propaganda, but
hey, wherein lies the truth?

My other comment concerns the statement as quoted from the study: 

> "Moreover, the scientists conducting the study found that clear-cut areas
>do not always slide more than uncut forests. In the Elk Creek region of
>Southern Oregon, for example, land covered with forests 100 years or older
>slid more frequently than clear-cut sections."<

It seems to me that this tends eliminate the arguement for preserving
old-growth timber in such areas.  The sooner the old-growth can be harvested
and replaced with young stands, the less stream siltation we will have! 
Assuming of course that stream siltation is a legitimate problem associated
with land slides.  

It is not beyond the imagination to envision what could happen when thousands
of tons of timber are standing on steep, rock underlayed slopes, that become
thoroughly rain saturated (80MBF per acre  represents about 1000 tons standing
on tract 208' square).  Remember, if that timber is putting on any net growth
at all, it is getting heavier every year, and think about what a little wind
along with an abnormally heavy rainfall would do!  A small example of this,
that we've all seen, is when a large tree above a creek bank kicks out and
slides into the creek.

Thanks Again!
------------------------------------

Seumas Mac Phadruig
Industrial Forest Opns. Mgr. (Ret.)
Inland Northwest, USA



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