05-12-2002, 03:26 AM
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Speakout: Clear-cutting for runoff 'delusional'
In article ,
writes:
The notion of clear-cutting huge tracks of forest to increase runoff for water
containments is not only self-serving industry pandering, but delusional.
While supporters hold up one carefully chosen test where some limited success
was realized, the practical, real world effects would be quite different.
Rather than being net depleters of moisture, trees and forests help increase
moisture by "fixing" it in ground and surface sources. Trees use some of the
moisture from snow in their upper stories while, aided by gravity, sun and
wind, they permit most to find its way to the surface. This surface moisture is
then shaded from excessive evaporation by the trees, allowing it to percolate
downward, maintaining soil moisture balance, feeding root systems, reducing
erosion, and recharging ground sources. Evapotranspiration from trees helps
maintain the water cycle and local climate.
Do you have any actual research to back this position? Generally I am of
the opinion that any ground that can grow trees should be growing trees,
but in some areas of the world trees are discouraged because of the
amount of water they use. I have talked to a farmer in South Africa who
was not allowed to plant trees in a riparian zone because of the amount
of water they would consume.
It takes about 20" of rain a year to grow a douglas fir. I'm sure the
Rocky Mountain pines are more frugal with their water, but just about
have to consume around a foot of rainfall a year.
What the result of logging would be on water supply is not clear to me.
I suspect it would be highly variable depending on slope and climate.
Probably the most effective way for Colorado to recover water is just to
outlaw lawn irrigation.
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http://home.teleport.com/~larryc
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