Landslides after clearcuts

dwheeler at teleport.com dwheeler at teleport.com
Sun Feb 22 01:26:26 EST 1998


In article <19980221231501.SAA04809 at ladder02.news.aol.com>,
  phadruig at aol.com (PHADRUIG) wrote:
>
>
> 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?
>
The study clearly indicates the landslides are twice as likely to occur after
clearcuts than with standing timber. This is not "environmental propaganda."

> 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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