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I:J§ij;mEVIEWEDI
SILVICULTURE
and NEW FORESTRY
in the PACIFIC
NORTHWEST
!?;;·;.�:jJx�l -1
he··'flerms new forestry, alternative silvicul­
.,.,J
'
tur , and ecosystem management have
cle outlines how silviculrural research and
be 'n used to describe current movements
aW' y-from management philosophies
silviculturists can complement work in
ward increasing consideration of other
on Pacific Northwest forests.
Pacific Northwest, much of the thinking
Historical Overview
term new forestry) arose in that region.
about forest management in the West re­
dominated by timber production and to­
forestvalues. Although not peculiar to the
and the strongest advocacy (including the
Silvicultural research has initially had
minimal influence on development of al­
other disciplines to develop management
practices that meet the demands placed
Most of the institutional memory
sides in the silvicultural community. This
includes appreciation of the historical
ternative practices proposed and, in some evolution of forest practices-major ob­
Service lands in the Douglas-fir region. complishments of the past 75 years. It also
cases, now being widely applied on Forest Ecologists, hydrologists, and wildlife bi­
ologists have been the major contributors stacles and problems overcome, and ac­
involves a cautious attitude drawn from
the memory of past mistakes, changes in
(Franklin et al. 1986, Franklin 1989, concepts of "good stewardship," and
Management Assessment Team 1993). times from long-term experiments.
Hansen et al. 1992, Forest Ecosystem There is considerable skepticism in some changes in inferences drawn at different
Fire was the greatest obstacle early in
quarters about the biological premises this century. No management was possi­
practices and approaches advocated in niques and fire control organizations had
1990, Mann 1990), although criticisms early to replant and suppress fire on
and the practical consequences of some the name of new forestry (Atkinson have been somewhat muted by political and institutional acceptance of the overall objectives (Atkinson 1992). Silviculture is by definition the ma­
nipulation of forest vegetation to attain
ble until effective fire suppression tech­
been developed. Decisions were made
burned-over and cutover lands on na­
tional forests. Methods had to be devel­
oped for seedling production and plant­
ing. Such developments, coupled with
gradual realization of the enormous
desired ends. Once objectives are defined,
growth capacity of Douglas-fir ( McArdle
and must play a major role in developing
to regenerate, protect, and manage their
silviculturists and silvicultural science can
techniques to attain them. Silviculturists
have information and perspectives that
are to some degree lacking in· much cur­
rent discussion. These include knowledge
of the history and rationale of conven­
tional forest management practices,
By DeanS. DeBell and
Robert 0. Curtis
ing new management practices. This arti­
and Meyer 1930), also led private owners
timberlands after the initial harvest.
Decisions to stay and invest were
milestones in forest conservation. These
accomplishments by federal and state
governments, and by industrial and other
private landowners, are often forgotten in
quantitative information on stand devel­
current controversies. Yet actions taken
treatments, and techniques for develop­
do not provide a favorable climate for in-
opment and response to silvicul tural
on current forest management issues that
December 1993 25
lt
vestments in nonfederal timberlands may
search involves studies
create rnore ecological, social, and eco­
that test hypotheses and
are already seeing accelerated and prema­
sessments of biological
nomic problems than they resolve. We
ture cutting of young timber on private
holdings, presumably caused by the un­
provide quantitative as­
r esponse in relatively
young stands (up to 100
certainty of future harvest restrictions
years). In contrast, much
severely reduced sales of public timber.
new forestry can be char­
about widespread adoption of untested
ecology, with heavy em­
cutting episode of the 1930s and 1940s
older stands. Most cur­
economic problems of the 1930s and
practices are based on hypotheses derived
(Kirkland and Brandstrom 1936). For a
constructive studies to establish their va­
in old-growth stands in Region 6, but it
was found wanting on both ecological
can broaden thinking; but quantitative
research is needed to resolve many ques­
was then quietly buried-so quietly that
feasibiliry.
and high stumpage prices associated with
Past mistakes should teach skepticism
practices. One illustration is the selective
(Smith 1970), proposed to remedy the
launched with a persuasive publication
time, selective cutting was widely applied
and economic grounds (Isaac 1956). It
many are not even aware of it.
Another past mistake was the at­
tempted transfer of practices that had
been successful in low-elevation forests to
t h e high-elevation true fir-hemlock
of the foundation for
acterized as descriptive
p hasis on unmanaged
rent proposals for specific
therefrom, without manipulative or re­
lidiry. Descriptive work and speculation
tions related to benefits, costs, risks, and
Fortunately, existing studies in the
Pacific Northwest provide many years of
record on topics such as selection of spe­
cies and seed sources; stocking effects;
growth and yield; and the influence of
rype-namely, clearcut, burn, and plant
associated vegetation on forest and soil
these areas were eventually stocked by
ments provide a valuable perspective and
Douglas-fir. After initial failure, many of
naturally seeded true fir and hemlock.
Today, with reduced use of fire, site­
development. These long-term experi­
a knowledge base that has not yet been
well incorporated into new forestry
specific species selection, better plant­
thinking. Interpretation of many studies
rrue firs, most such areas can be promptly
Early performance and appearance were
ing stock, and advance regeneration of
regenerated (Emmingham and Halver­
son 1982).
Some silviculturists draw parallels be­
tween certain aspects of new forestry and
these and other old embarrassments. A
better understanding of the history of
has changed drastically over the years.
often not good indicators of long-term
results. The magnitude and importance
of proposed changes argue for a system
of well-designed and implemented stud­
ies to assess the merits and drawbacks of
current and potential practices. This is
tively than could any single organization.
experience.
Application to Current Issues
may take decades of experimental work.
a vast amount of data pertinent to current
forest management should help retain
an area where silviculturists have much
problems already solved from reappear­
Reliable answers to some questions
past gains in forest conservation, prevent
ing, and avoid new problems.
Silvicultural C ontributions
Silviculturists can make major contri­
forestry issues. Although this information
their experience with retrospective stud­
volving management of the tree compo­
now. Silviculturists can assist by applying
ies to obtain interim information. Histor­
the stand level; although the pattern of
ularly helpful in analyzing the past
must also be considered. Much of new
forestry has focused on a landscape per­
Over the last 25 years, silviculturists
stand structures across the landscape
;pective, but a solid understanding of
stand -level dynamics is important to this
larger scale.
Silvicultural knowledge rests on a
combination of experience, observation,
and experimental research. Most of its re­
26 Journal of Forestry
Silvicultural studies have accumulated
Yet management decisions must be made
butions to development and assessment
of new forestry practices-primarily at
and facilities resources to collect data and
test or model relationships far more effec­
ical reconstruction techniques are partic­
development of existing stands.
have organized and operated many of the
research cooperatives that have helped
develop and refine intensive cultural
practices. These cooperatives, commonly
based at public universities but composed
of a variery of organizations, provide a
means of pooling financial, human, land,
is important to decisions and practices in­
nent of forest ecosystems, individuals and
organizations-even professional re­
source managers-seem to lack a general
understanding. Four examples are dis­
cussed below.
Stand dynamics. Most naturally estab­
lished northwestern forests owe their ex­
istence and characteristics to periodic
wildfires. The Northwest was never a
continuous expanse of old-growth; the
presettlement forest was shaped by fires
large and small, at intervals of one to sev­
}t !.•:.
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Figure 1 (opposite page, left) presents a healthy, intact stand
of old-growth Douglas-fir on the Big Bar Ranger District,
Shasta- Trinity National Forest, Califomia. Figul'e 2 (oppo­
site page, below) shows. a contrasting deteriorating stand of
old-growth westem hemlock and Douglas-fi1' on the Wind
River Range1· District, Gijf01·d Pinchot National Fol'est,
Washington. Figul'e 3 (below) and figure 4 (right) illustrate
an unthinned and a thinned stand, l'espectively, ofDoug/as­
fir in the Mt. "Walkel' thinning study, Quilcene Ranger Dis­
trict, Olympic National Forest, Washington.
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stands of the future will
be today's 120- to 180­
year-old stands, many of
which were established
following severe fires in
the early 1800s. To pro­
era! hundre d years (Agee 1991). Most
srand·s·are and always- were essentially
even-aged in youth. In the absence of dis­
turbance, they gradually develop into the
old-gro wth stage with an uneven-aged
structu re and irregular canopy (Oliver
and Larson 1990). Change is continuous,
even in 400- to 500-year-old stands (De­
Bell and Franklin 1987). Age and accu­
mulatin g stresses eventually lead to the
death of individual large trees and general
stand deterioration-disease, decay, and
loss of major tree species. Present forests
cannot be preserved indefinitely in some
idealized "state of nature," since that state
involves catastrophic fires that are unac­
ceptable in a populated region.
This subject of continuous change in
vide old-growth experi­
portunities to provide such a mix on pub­
lic lands are probably greater today than
they were 50 years ago.
Silvical traits and silvicultural systems.
Management of forest species offers more
latitude than many people think-cer­
"mature" stands of today.
traits in unmanaged environments and
als of young forests, which usually focus
present managed landscapes. Some natu­
velopment in plantations, before differ­
management. For example, the common
turn 04r attention to managing these
Similar shortcomings exist in portray­
on the most uniform phase of stand de­
tainly more than can be inferred from
more than one would surmise from
ral constraints are easily overcome by
enriation and mortality have stimulated
belief that western redcedar is slow-grow­
changes are inevitable, as evidenced by
tial stems from the fact that in most nat­
horizontal and vertical diversity. Such
most older stands.
The rate and nature of change can be
ing and has limited management poten­
ural stands the species was a late-arriving
component of the understory in mixed
profoundly influenced by silvicultural
stands that contained rapidly growing,
many professionals in allied fields. A vivid
cedar established in even-aged stands may
ning study established in a 60-year-old
and western hemlock on many sites
practices, a fact not fully appreciated by
example is provided in a long-term thin­
low-site stand some 50 years ago. Un­
thinned plots are still quite dense, with
linle undergrowth or multiple layering of
(jig. 1). Few if any illustrations
were periodically thinned have developed
stands
stages (Oliver 1992). Fortunately, the op­
ences for future generations, we should
the forest has been given short shrift.
Photos of old-growth forests depict ca­
thedral-like groves and relatively intact
bution-in time and space-of many
the canopy (fig. 3). In contrast, plots that .
long-lived species. Yet young-growth red­
equal the growth and yield of Douglas-fir
(Nystrom et a!. 1984)
A wide variety of silvicultural systems
have been in successful use for many years
throughout the world (Schlich 1897, Fer­
now 1911, Troup 1928, Spurr 1956); "al­
show old-growth stands with little or no
larger trees and a diverse, lush understory
ternative silviculture" is far from new. But
and extensive heart rot; and where the de­
(fig. 4).
Foresters need to help resource profes­
esters have concentrated on even-aged
Douglas-fir; where most of the remaining
dominant trees have dead or broken tops
with a multilayered, multispecies canopy
for the past 30 years North American for­
systems (mainly clearcutting) in both re­
veloping understory thickets of true fir
and hemlock are heavily infested with
sionals, policymakers, and opinion lead­
search and practice, primarily because
to provide cathedral groves for future
generations b y simply preserving today's
o ld-growth. Rather, the magnificent
through successive stages of forest devel­
opment. Each stage provides some values
primary objective is wood production.
better than other stages, and sustainabil­
clearcutting may stem in part from infre­
dwarf mistletoe (fig.
2). It is not possible
ers understand that each stand goes
ity of all values requires a balanced distri­
these systems are very efficient when the
T he con ti n u e d intensive a t t a ck o n
quent use of other silvicultural systems,
December 1993 27
even when alternatives are suitable. Sur­
vival of clearcutting as a viable tool may
patch cuttings.
rofessional and lay
P
opinions about for­
Each of the five man­
est management
agement systems and the
practices have become
polarized, caused in part
unmanaged control will be
imposed in stands of at
least 35 acres and will be
by ideological differences
i
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and in part by inadequate
replicated in eight blocks,
information about effects
of management on many
Washington. The blocks
four each in Oregon and
will differ in stand and
forest resources and val­
ues. The Demonstration of Ecosystem
landscape characteristics and will be rep­
Management Options project may help re­
resentative of conditions commonly faced
solve such conflicts by providing informa­
by managers of westside forests.
tion on biological, social, and economic
Within the constraints inherent to the
consequences associated with different
various retention treatments, initial har­
management strategies for forest ecosys­
vesting and subsequent cultural practices
tems in the Douglas-fir region.
The DEMO project began in 1993 when
Congress allocated funds and directed the
acteristics associated with late-succes­
USDA Forest Service Region 6 to establish
alternative harvesting experiments in Ore­
gon and Washington. The project
will be implemented by na­
tional forest managers in as­
(including planting) will foster stand char­
sional forests, including mixed species
composition; large trees; snags and down
trees; and horizontal and vertical diversity
in vegetative structure. Many as·
peels of overstory and under­
story vegetation will b e
sociation with the Pacific
m o n i t o r e d-s u r v i v a I,
Northwest Research Sta­
damage, and growth of
tion and several other
parties.
residual trees; dynamics
of snags and down trees;
establishment and growth
DEMO w i l l d emon­
strate and evaluate alterna­
tive approaches for managing
forests in which Douglas-fir is the
predominant species, and maintenance of
of tree seedling regenera·
lion; and survival, damage,
and growth of woody and herba·
ceous understory plants.
late-successional or old-growth attributes
Assessment will extend to other re­
is a major consideration. The approaches
sources and values. Population densities
will include even-aged, two-aged, and un­
of and habitat use by several species of
even-aged management systems, all of
small mammals, birds, and reptiles will be
which appear biologically and operation­
determined. The abundance and dynam·
ally feasible. The systems differ substan­
ics of mycorrhizae and other mushroom
tially in density of residual stands following
fungi will be evaluated. Soils and hydrolog­
initial harvesL'regeneration cuts, which will
ical research will include disturbance and
create a spectrum of disturbance levels
compaction of forest floor and surlace soil,
and biophysical environments.
The systems (or treatments) are de·
water flow paths, snow accumulation and
melt, and contribution of rain-on-snow
fined in terms of percent of basal overstory
events to stream flow.
100 (unmanaged control stand). In the 20
harvesting costs, stumpage values, future
retained: 0 (a clearcut), 20, 40, 60, 80, and
percent and 40 percent retention treat­
ments, half of the residual trees will be
Economic assessments will include
stand growth, values of residual trees, and
other commodity and noncommodity con­
grouped in uncut two-acre patches and
siderations. Public perceptions will be ex­
half will be dispersed throughout the cut­
amined in relation to general attitudes, ac­
over area. For the 60 percent retention
treatment, the harvest will be a combina­
tivities, and amount of information that
individuals have about the intent of each
tion of small patch cuttings (about two
option. The DEMO installations are also
acres) and dispersed thinning. The ini­
expected to provide opportunities for pub·
tial harvest in the 80 percent retention
treatment will occur entirely in small
lie involvement, training, and collateral sci­
entific studies.
hinge in part on the willingness and abil­
ity-of foresters to apply other systems. For
example, shelterwood cutting has been
successfully applied in the Douglas-fir re­
gion, with and without planting. Planned
experiments must be conducted with dif­
ferent systems-it is unlikely that we
have achieved the only practical solution
to sustained tree production on many
sites, or that we are providing an opti­
mum mix of forest conditions and values
on lands where multipurpose manage­
ment is appropriate.
The planting option. A discussion of
planting can serve as a surrogate for dis­
cussion of other cultural practices-ge­
. netic improvement, fertilization, growing
stock control-that provide opportuni­
ties not understood and appreciated our­
side silvicultural circles. This lack of un­
derstanding arises in part from mislead­
ing and erroneous information on planta­
tion forestry, and in part from the natu­
ralistic ideology rhat permeates much of
the current debate over forest manage­
ment. This view-that nature knows
best-can become an excuse for mini­
mizing present expenditures by not in­
vesting in new stand establishment. The
end results may be far from those desired.
In many instances, "savings" in past de­
cades had results undesirable from rhe
standpoint of esthetic values, wildlife,
and wood producrion.
Certainly rhere are situations where
natural regeneration should be used; but
there are also many situations where
planting is most desirable. Planting pro­
vides greater control of spacing and com­
position of the next stand. It enables for­
est managers to consciously establish
mixed stands, influence quality and ge­
netic composition, reduce the period be­
tween harvest and reestablishment of tree
cover, and reduce the exposure of mineral
soil (required for natural establishment of
some species).
Planting also substantially increases
wood production. One study showed vol­
ume production of 35- to 38-year-old
plantations was 40% higher than that of
adjacent natural stands of the same age;
and such productivity increases occurred
without genetically selected stock or
modern nursery procedures (Miller et al.
993). A second study related to "corn­
field forests" (an unfortunate metaphor
for a situation hard to find in the West).
28 Journal of Forestry
lengthen time to culmination. Long-term
icy have major influences on forest man­
still far from culmination at age 50 (Cur­
s idered in d iscussions of r e s o u r c e
Murray a n d Harrington ( 1990) found that volume production of 24- to 27­
thinning studies indicate that stands are
was 40%-150o/o higher than projected tis 1992a).
include greater site and stand uniformity and fewer problems caused by such "bio­
that culmination of mean annual incre­
nutrients tied up in large organic debris, that are repeatedly thinned ( Curtis
estS" or "biological legacies"-are all good
or all bad. Each must be evaluated in
seems to have a relatively broad plateau,
. year-old plantings on former farmland yields of natural stands. Possible reasons logical legacies" as endemic root diseases, and competition from understory species. Few things-whether "cornfield for­
terms of desired objectives and tradeoffs;
and the information must be used to de­
velop better, rnore acceptable strategies
and combinations of strategies for forest­
land management. Planting and other in­
tensive practices, and single-use or domi­
nant-use intensively cultured plantations,
are tools-just as are wilderness areas and
habitat enhancement areas-that can be
used to meet the multitude of needs and
values that can derived from forestlands.
Rotation age and mean annual incre­
mmt. Many issues in forestry today are
linked to rot ation length and recent
trends toward short rotations. Extended
rotations, in combination with other
practices, mean less land in regeneration
and early developmental stages; hence es­
thetically more appealing landscapes, less
slash burning , reduced herbicide use,
larger rrees, more natural snags, greater
opportunities to develop and manipulate
understory and shrub layers, and in­
agement decisions, and they must be con­
problems and possible solutions. Many of
Several simulation models indicate
the issues cannot be dealt with solely o n
ment for Douglas-fir is later than com­
phasis is on public lands, discussion
monly thought, particularly in stands
1992b, Curtis 1993). The curve depict­
ing the pattern of increment over time
allowing considerable flexibility in select­
ing rotation ages that provide essentially
similar increment and yield.
Short rotations impact long-term tim­
ber supply. With the 50-year rotations
commonly projected on industrial lands
public lands. Although the current em­
and analysis must include basic socio­
economic, ecological, and operational
feasibility considerations that affect all
forestlands. mii
Literature Cited
AGEE, J.K. 1991. Fire history of Douglas-fir for­
ests in the Pacific Northwest. In Wildlife and
vegetation of unmanaged Douglas-fir forests.
L.F. Ruggiero et al., eds., p. 25-33. USDA
For. Sem Gen. Tech. Rep. PNW-GTR-285.
533 p.
in the Pacific Northwest, mean annual
ATKINSON, W.A. 1990. Another view of new for­
60%-80% of that obtainable with longer
estry, D. Hopwood and L. Island, appendix
cubic volume production may be only
rotations. The short-rotation yield reduc­
tion is greater on poor sites and in stands
with low initial stocking. Similarly, the
percentage reduction is greater for re­
gimes with repeated thinning and when
larger minimum sizes and log quality are
considered.
Many foresters are concerned about
the economic effects of removing more
land from the commercial timber base.
The credibility of these warnings is di­
minished if much of our land is inten­
tionally harvested at an age where only
60%-80% of its potential is realized. Tax
laws and other aspects of our socioeco­
estry. In Principles and practices of new for­
5. BC Min. For., V ictoria. Land Manage.
Rep. 71. 9 5 p.
--
. 1992. Silvicu!tural correctness: the po­
liticalization of forest science. West. W ild!.
17(4):8-12.
CURTIS, R.O. 1992a. Levels-of-growing-stock co­
operative study in Douglas-fir: Report !!­
Stampede Creek: a 20-year progress report.
USDA For. Serv. Res. Pap. PNW-RP-442. 47 p.
--. 1992b. A new look at an old question­
Douglas-fir culmination age. West. J. Appl.
For. 7(4):97-99.
. 1993. Douglas-fir rotations-time for
---
reappraisal? West. J. Appl. For. 8(3):1-5.
DEBELL, D.S., and J.F. FRANKLIN. 1987. Old­
growth Douglas-fir and western hemlock: a
36-year record of growth and mortality.
creased carbon storage. They also offer
nomic structure may need modification
and perhaps improved long-term forest
ble; governmental incentives and tax
Community types, productivity, and refores­
objectives for many other sectors of the
In True-fir symposium proceedings, C.D .
better habitat for some wildlife species
to make longer rotations financially feasi­
productivity.
structures already promote public policy
Of many changes in forest practices
that could provide additional values, ex­
tending harvest· age may be the least dis­
ruptive and involves the least uncertainty.
It can be applied to existing stands, and it
can use well-established techniques of
thinning, reg eneration, and growth-and­
yield projection.
The feasibility of longer rotations de­
pends in part on effects on timber yields.
On national forest lands, minimum rota­
tion length is set by law to approximate
the age at which mean annual increment
culminates. Private and industrial owners
use rotations based on financial criteria
and supply and policy constraints, which
are related to the mean annual increment
pattern. Mean annual increment patterns
and age of culmination are affected by
m a nagement, and stocking control can
regional and national economy.
Conclusions
West. J. Appl. For. 2:111-14.
EMMINGHAM, W.H., and N.M . HALVERSON. 1982.
tation: management implications for the Pa­
cific silver-fir zone of the Cascade Moun rains.
Oliver and R.M. Kenady, eds., p. 291-303.
Univ. Wash., Seattle. Inst. For. Resour. Con­
trib. 45.
Silviculturists have much to contrib­
FERNO\XI, B . E. 1911. History of foresrry. Univ.
management practices through both
FOREST EcoSYSTEM MANAGEMENT ASSESSMENT
ute to new forestry and improved forest
knowledge and experience, and their per­
spectives can complement those of the
other resource specialties. Better under­
standing and communication among dis­
ciplines is badly needed. All groups need
Press, Toronto. 506 p.
T EAM. 1993. Forest ecosystem management:
an ecological, economic, and social assess­
ment. In Draft environmental impact state­
ment on management of habitat for late-suc­
cessional and old-growth forest-related
species within the range of the northern spot­
to understand the relationship of stand
red owl, appendix D. USDI For. Serv. et al.,
and dead) to wildlife, watershed, and es­
FRANKLIN, J. 1989. Toward a new forestry. Am.
attributes (overstory and understory, alive
thetic values, and how silvicultural tech­
niques can maintain and enhance these
values along with continued commodity
production. ·
In addition, economics and social pol­
Portland, OR. 1,000 p.
For., Nov./Dec., p. 1-8.
FRANKLIN, J.F., T. SPIES, D. PERRY, M. HARMON,
and A. Mc KEE. 1986. Modifying Douglas-fir
management regimes for nontimber objec­
tives. In Douglas-fir: stand management for
the future, C.D. Oliver and J.A. Johnson,
December 1993 29
TREE
PROTECTORS Which is best? Which is most efficient? The health of your trees
depends on getting
eds., p. 373-79. Univ. Wash., Seattle. Inst.
1984. Development of young growth west­
For. Resour. Con trib. 55.
ern redcedar stands. USDA For. Serv. Res.
HANSEN, A.J., T.A. SPIES, F.J. SWANSON, and J.L.
Pap. PNW-324. 9 p.
OHMANK. 1992. Conserving biodiversity in
OLiVER, C.D. 1992. Achieving and maintaining
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biodiversity and economic productivity-a
ISAAC, L.A. 1956. Place of partial cutting in old­
accurate information.
landscape approach. J. For. 90(9):20-25.
growth stands of the Douglas-fir region.
OLIVER, C.D., and B.C. LARSON. 1990. Forest
USDA For. Serv. Res. Pap. PNW-16. 48 p.
stand dynamics. McGraw-Hill, Inc., New
KIRKLAND, B .P., and A.J.F. BRANDSTROM. 1936.
York. 467 p.
Selective timber management in the Doug­
ScHUCH, W. 1897. Manual of forestry. Vol. II:
las-fir region. Charles Lathrop Pack For.
Practical silviculture or formation and tend­
ing of woods. Ed. 2. Bradbury, Agnew & Co.
Found., Washington, DC. 122 p.
MANN, J.W. 1990. Proposals for alternative silvi­
London. 331 p.
cultural practices and "new forestry"-are we
SMITH, D.M. 1970. Applied ecology and the new
Proceedings, Society of American Foresters
Coordination Commission, p. 3-7. West.
on the right track? In Are forests the answer?
forest. In Proceedings, \'ifestern Reforestation
For. & Conserv. Assoc., Portland, OR.
national convent-ion, p. 313-17. Soc. Am.
For., Bethesda, MD.
SPURR, S.H. 1956. German silvicultural systems.
McARDLE, R.E., and W.H. MEYER. 1930 (rev.
For. Sci. 2:75-80.
1949, 1961). T he yield of Douglas-fir in rhe
T Rot:P, R.S. 1928. Silvicultural systems. Oxford
Pacific Northwest. USDA For. Serv. Tech.
call today for your Free Sample
MILLER, R.E., R.E. BiGLEY, and S. W EBSTER.
and a copy of a comparison
study by the Pennsylvania
Bureau of Forestry.
soo-a75-B071
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A B O UT THE A U T HORS
Dean S. DeBell and Robert 0. Curtis are
researchforesters, Silvicttlture Team, Pacific
Northwest Research Station, USDA Forest
Service, Olympia, WA 985 12-9 193. This
article is based in part on a presentation at
the 199 1 Forest Vegetation Management
Conference, Redding, California.
after slash burning in the Cascade Range.
Mt:RRAY, M.D., and C.A. HARRINGTON. 1990.
Y ield comparison of three Douglas-fir planta­
Lafayette, IN 47905
or
1993. Early development of matched planted
and naturally regenerated Douglas-fir stands
West. J. Appl. For. 8(1):5-10.
TREE PRO
445 Lourdes Lane
Univ. Press, Oxford, UK. 199 p.
Bull. 201. 64 p.
317-463-1011
tions on former farmland in western Wash­
ington. West. J. Appl. For. 5(4):123-26.
NYSTROM, M.N., D.S. DEBELL, and C.D. OuvER.
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