WSP02037

• File Number: 8200.700
• Description: Colorado River Basin - General Publications
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 11/1/1979
• Author: US Forest Service
• Title: Managing Vegetation to Increase Flow in the Colorado River Basin - US Forest Service
• Water Supply Pro - Doc Type: Report/Study

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Figure lO.-Projected waler yield IncreUe$ !rom specillc
management strategies in lodgepole pine and spruce-fir
lorests (leal and Aluander 1975).

Figure 11.-Mi..d conller loresls. including Douglas-Ilr In
the Southwest occuPY' about 400.000 acres In the lower
Cotor.do Rly.' B.sln.

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Figur. 12.-PotenUal wate, yield incr.ases Irom mixed
conlle, fOftlsts .s. lunctlon oltha percenl 01 watershed
In openings 3 10 8 Ir.e heights in diameter and the ..-
peeted yield without II.atmenl (Rich and Thompson
1974).

spruce-fir (fig. 10) was similar. excppt thai the
patch cuts would he made at 50-year intervals. III
much of the Rod.y ~1()untain area. patch cutting is
considered ecologically sound if the management
objec!iv(! is to maintain the spruce-fir ecosystem
(Alexander 197.n t

Suuthwesh'Tll ~Jixed Conifer FOH~sts

~lix(~d conifer forests (fig. 11) in the Southwest
occupy sites thaI are welkr and cooler than usually
uccupied by pure stands of pondl'rosa pine and
wamwr, bul not necessarily drier, than subalpine
fowst sites 10 the north. The most common o\'er-
ShH~' species are rJouglas-fir. ponderosa pine,
whih! fir. Engelmann spruce. aspen, southwestern
white pine. bhw SprllC(!. and corkbark fir. ~1ost of
the mixed conifer stands aft! found be!\....een 7.000
and 10.000 feet elevation. Aho\'e 10.000 feet.
mixt!d conifers gh'c way to spruce-fir forests.
Douglas-fir is the most important commercial
timber species. For purposes of this report. all
spruce-fir in the Lower Basin is included in the
mixed conifer type. Togt!thcr they occupy nearly
.tUU.DOO acres. mostly commercial. Precipitation
averages 25 10 more than 30 inches jwr \'eM; one-
half ur mOTe of it comes as soow. Water ~:ield aver.
ages J to 5 inch,'s. sometimes more on Ihn \\'t!tlesl
sites; three-fourths ur morn of il is from snowmelt.
Using management strategies similar to those
described for subalpine fowsts. the potential for
increasin!,: water yield in the mixed conifer forests
is t'stimatf>d to be about 25% tt!% than in the sub-
alpine. although large dparcuts apptMr 10 ~i\'e
greater increases in the mixt'd cunifer than in the
subalpine. :\ possible explanation for this is that in

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