Western Forester
February l984-Page 11
Don't Write Off Poor-Site Lands By Don Reukema and Dick Miller
Unmanaged natural Douglas-fir stands
Wider spacings had greater and longer
and plantations grow very slowly on site
lasting increases in diameter growth than
the closer spacings. Volume growth rates
are still increasing at all spacings, and the
IV IV
land.
For
management
this
reason,
(investments
in
timber
cultural
practices) on such sites is commonly
assumed to be unprofitable.Recent results
of two of our long-term studies of thinning
and fertilizing in a poor-site Douglas-fir
stand on the Gifford Pinchot National
Forest indicate, however, that such sites
are
often
capable
of
producing
mer­
chantable trees within a reasonable time if
trees are given ample growing space and,
particularly, if fertilized.
A portion of this site V stand, planted at
Harrington and Reukema and Miller and
Tarrant in the March 1983 issue of Forest
Science (Vol.29, No.1).
Although these two studies were at a
single location, they are unique in their
differences
among
spacings
have
diminished over time. Although the 20-foot
long-term record of response. Results are
spacing has only one-third the number of
trees of the 11-foot spacing, in the most
studies and may be applicable to most site
consistent with short-term results of other
recent 5 years its net volume growth was
90 percent of that at the closer spacing (87
IVIV land within the coastal Douglas-fir
type. Shoft;term results from other studies
vs.97 cubic feet per acre per year).
An unthinned portion of the same stand
volume from the combination of thinning
also indic te that gains in merchantable
was fertilized at age 37 with 140 to 420
pounds of nitrogen per acre. Fertilizer
and fertilizing will ,exceed gains when
these practices are applied separately-as
greatly increased both diameter and
8-foot spacing, was thinned at age 27 to height growth over the subsequent 15
average spacings of 11 to 27 feet. years of observation. Gross .volume
Development of the stand over the next 25 growth of fertilized plots was 40 to 103
years showed initial detrimental effects percent more than that of controls,
from thinning, followed by marked ac­
celeration of both diameter and height
growth. Although height growth was
reduced during the first 10 years after
thinning, it later increased and during the
most
recent
10
proportional to
indicate
that
was
nearly
growing space.
years
Trends
all
it
thinned
stands
will
they were at our study area.
The poor performance of unmanaged
stands on such sites clearly does not
represent
their
potential
to
produce
cubic feet per acre. Fifteen years after
merchantable volume; research trials
demoestrate that thinning and fertilizing
can mcrease timber production. This
evidence
counters
the
widely-held
fertilization, volume on the fertilized plots
was 25 to 69 percent more than that on the
controls, with a much larger proportion of
low-site lands is uneconomical. We urge
that economic analysis be more specific.
corresponding
to
gains
in
volume
production over the 15 years of 765 to 1,980
generalization that management of such
this volume in larger trees. Clearly, a one­
produce taller trees than the unthinned
time fertilization with nitrogen markedly
increased volume and value of this
(1 J The authors are, respectively, prin­
cipal silviculturist and principal soil
stand and that height will increase with
plantation.
scientist at the USDA' Fotest Service
Forestry Science Laboratory in Olympia,
spacing up to at least 20-foot spacing.
For more information, see articles by
WA.
Reforestation Services, Inc. •
Chemical Supply and Application
•
Application Only
GIL LIMING, PRES.
LARRY LIMING, V. PRES.
Ground Applications:
•
Roadside Vegetation Control
•
Mill Sites
•
Industrial Areas
Aerial Applications
•
Spraying
•
Fertilizing
•
Drip Torching
•
Seeding
Reforestation Services, Inc.
Service to the Western U.S. since 1959.
P.O. Box 3197
.
Sa lem, Oregon 97302
503/362-8322
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