http://www.insidedenver.com/drmn/opi...581500,00.html

Speakout: Clear-cutting for runoff 'delusional'
By Harv Teitelbaum, Special to the News
December 2, 2002

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.

On the other hand, open landscapes of snow are like open water reservoirs,
i.e., massive moisture evaporators. Not only would the result of massive
clear-cutting be a net loss of ground and surface moisture due to increased
evaporation, but the unshaded soil would lose moisture in the summer and
whenever it lacked snow cover in winter, it would dry and harden thus favoring
weeds and other invasives over native grasses and forbs, and erosion would
increase.

Plant and animal diversity would decrease. Population imbalances would
increase.

A Canadian study found that south-facing slopes received, on average, five
times the solar radiation as north-facing slopes and, as a result, produced
much less runoff compared to north-facing slopes. In many areas, the study
found that south-facing slopes produced no consequential runoff at all. Not
surprisingly, south-facing slopes also have a much higher fire frequency. So
the irony is that clear-cutting south-facing slopes for fire mitigation might
also eliminate what little runoff potential there is, as tree cover is the only
feature allowing these aspects to retain moisture. At the same time,
clearcutting north-facing slopes might benefit runoff in limited applications,
but have far less potential to mitigate fire frequency.

The Lake District of northern England is indicative of what can happen to a
landscape after its forests have been removed. Until recent restoration efforts
began, centuries of clear-cutting had left this area almost completely devoid
of trees. The result is a stark region of little more than sheep grass and
rocks. The soil has become so paper thin that there is little left to erode.
Travelers are continually making new trails, as even a few passes expose the
loose rocky substrate. Wildlife is almost nonexistent; the climate, unmoderated
and severe.

Imagine what would happen if Colorado took this scheme to its logical extreme.
We know that most of our water supply comes from snowpack and not rain.
Significantly reducing forest cover, combined with global warming, itself
exacerbated and ignored by the same industry-government alliance, would further
skew our precipitation mix toward rain. The long-term effect would not be
increased water supply for developers, but the desertification of the eastern
half of our state.

Less snow, less overall precipitation, less ground source recharge, altered and
desertified ecosystems - these are just some of the consequences of this
scheme. There will almost certainly be others. Of course, if recent official
attitudes are any indication, even desertification and the drying up of much of
our water supply would not hold developers back. This is an indication of where
both the real problem and real solution lie.

Clear-cutting and other supply-side schemes of developers and conservatives
could be compared to buying new and shinier buckets rather than fixing the hole
in the roof. Proposals for new containments, whether or not they prove
temporarily effective, merely distract us from considering the kinds of growth
controls necessary to get a real handle on our water supply problems.

Only after controlling demand will efforts at securing an adequate supply have
any hope of success.

Meanwhile, instead of clear-cutting, the logical course might be to uniformly
thin smaller-bore trees across all slopes, while removing brush and litter.

This would decrease fire severity and modestly increase runoff opportunity,
while maintaining the hydrological cycle, ground source recharge, shade,
biodiversity and habitat. Doing so at lower elevations would aid fire
mitigation, while thinning at higher elevations might improve runoff.