Is selective felling possible in BC's coastal forests?

PHADRUIG phadruig at aol.com
Sat Jan 31 20:46:03 EST 1998


In my estimation there are three basic factors involved in the decision of
clearcutting v.s. partial cutting:  physical, silvicultural and economic. 

The physical factor is concerned with the height, diameter and density of the
stand, and is the primary consideration in choosing the cutting method.  In
even aged stands, which comprise much of the American northwest coastal forest,
the trees grow up together in as dense a stand as can survive the competition
for sunlight. Individual trees grow tall and slender, and are thus
interdependent with regard to wind resistance.  Individual tree selective
cutting in this type of stand generally leads to the creation of a huge mess as
the residual trees are very susceptable to wind breakage and blowdown.  The end
result is often the same as a clearcut but with severe loss in value of the
residual volume.

The silvicultual factor is coupled with the successional nature of forest
establishment.  Douglas fir, the most desired NW Coast species, is not the
climax species.  The virgin Douglas fir stands that we find on the west coast
established themselves as the result of huge forest fires, probably 200-600
years ago.  You will not find Douglas fir seedlings thriving under the old
growth canopy since they require more sunlight.  Instead we find Hemlock and
Cedar.  These species represent the later successional stages of the NW Coast
forests.  To make a long story short, if you do individual tree selective
cutting in a coastal DF stand you will convert it into a Hemlock and Cedar
stand.

Regarding the economics, there seems to be a general belief that clearcutting
is done simply because logging in concentrated blocks is cheaper. This is, of
course, not the case. Selective cutting which removes only the larger trees is
generally cheaper than clearcutting which results in a smaller average piece
size.  But it is when you add the necessity of cable yarding, which applies to
much of the NW Coast forest and requires periodic costly moves and setups, that
the concentrated volume of clearcutting becomes more critical.

Minimum clearcut size, I think, is basically function of move in and setup
costs, v.s. volume per acre, but other considerations include terrain features,
feasible road locations and construction costs as well as the proximity of
cutting units.  

A "normal" setting for yarding equipment reaching out 1200 feet is probably
about 20 acres, while that for equipment capable of reaching out 1800 feet is
about 40 acres.  So consideration should also be given to the capabilities of
equipment in current use.  But also, to limit clearcut size to a single setting
would require a series of such clearcuts in close proximity, otherwise move in
costs would become prohibitive. 

An absolute rule as to clearcut size would not be a good idea since it would be
detrimental to good forest management.  Cutting boundarys should not be based
on a mechanical function but should consider terrain and timber
characteristics. Some flexibility is need such as a maximum average size of say
30 acres within a given area,  with an absolute maximum of say 50 acres.
 
Hope this gives you some food for thought.
Seumas.
-------------------------------
Seumas Mac Phadruig
Industrial Forest Opns. Mgr. (Ret.)
Inland Northwest U.S.A.


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



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