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THE PACIFIC NORTHWEST STAND MANAGEMENT COOPERATIVE AND ITS FIELD INSTALLATION DESIGN H. N. Chappell, R.
0.
Curtis, D. M. Hyink, and D. A. Maguirel
ABSTRACT.
The Stand Management Cooperative is a joint effort of twenty­
two organizations in the coastal Pacific Northwest to meet data needs for
construction of growth models. The data base will be specifically ap­
plicable to young stands, many of them plantations.
The Cooperative
addresses both the conventional measures of response to silvicultural
treatment and the effects of treatment on wood quality.
Data will be used
to develop models to guide management of large areas of young stands by
providing better estimates of the consequences of alternative management
regimes.
Cooperative objectives and standard designs adopted by the
Cooperative for permanent plot installations are described.
INTRODUCTION
Over the years many organizations have established permanent plot experi­
ments in Douglas-fir (Pseudotsuga menziesii [Mirb.]
Franco) and western
hemlock (Tsuga heterophvlla (Raf.] Sarg.) forest types in the coastal
Pacific Northwest. During the past decade there have been a number of
efforts to bring this information together for silvicultural interpreta­
tions and construction of growth and yield projection systems.
These
efforts revealed several problems, including data incompatibility and the
realization that although considerable permanent plot data exist for these
types, relatively little of it is applicable to the stand conditions we
expect in the future.
Starting about 1982, a number of organizations began joint discussions
concerning possible cooperative efforts to develop needed data.
Several
working groups reviewed the situation and confirmed the need for high­
quality, consistent, and compatible data on (1) effects of early density
control, specifically including very wide spacings, (2) effects of later
silvicultural treatments applied to stands that have had such early
density control, and (3) effects of early density control and later
silvicultural treatments on wood properties and value.
1 Director, Stand Management Cooperative, College of Forest Resources,
University of Washington, Seattle, WA 98195; Principal Mensurationist,
USDA Forest Service, Pacific Northwest Forest and Range Experiment
Station, 3625 93rd Avenue SW, Olympia, WA 98502; Biometrician,
a d Assistant Professor,
Weyerhaeuser Company, WTC 2H2, Tacoma, WA 98477;
College of Forest Resources, University of Washington, Seattle, WA 98195.
Presented at the IUFRO Forest Growth Modelling and Prediction Conference,
Minneapolis, MN, August 24-28, 1987.
1073
Current thinking in the region favors much wider spacings than have been
common in the past. We lack information on the response of such stands to
treatment. Of particular concern is the lack of specific quantitative
information on the effects of such regimes on wood quality, although the
information available suggests that wood quality may be the major factor
determining acceptable management regimes.
These discussions led to
formal establishment of the Stand Management Cooperative in January 1985.
THE STAND MANAGEMENT COOPERATIVE
The purpose of the Stand Management Cooperative is to provide a continuing
source of high-quality data on the long-term effects of silvicultural
treatments and treatment regimes on stand and tree development and wood
quality. The integrated program aims to quantitatively define effects of
treatments on growth, yield, and wood properties, and to forecast more
accurately the consequences of alternative management regimes.
Cooperative activities are restricted to two species, Douglas-fir and
western hemlock, in the coastal Douglas-fir region of Oregon, Washington,
and British Columbia. Other species will be included in the future if
there is sufficient cooperator interest. Plots will be established in
planted stands or stands with early density control, over a wide range of
site conditions and geographic areas.
The Stand Management Cooperative currently comprises twenty-two member
organizations (Table 1) . Sixteen contributing member organizations
representing forest industry and federal, provincial, and state agencies
provide support and direction for the project. Six institutional members
participate in the Cooperative, furnishing technical expertise and
research support. The University of Washington serVes as Cooperative
headquarters and provides program administration and staffing.
Table 1. Member organizations of the Stand Management Cooperative.
Institutional members marked with "*"
Port Blakely Tree Farms Simpson Timber Company University of British Columbia* University of California, Berkeley *
University of Washington *
USDA Forest Service
USDI Bureau of Land Management
Washington Department of
Natural Resources
Washington State University *
Weyerhaeuser Company
Willamette Industries
Bohemia, Inc. British Columbia Ministry of Forests and Lands
Cavenham Forest Industries
Champion International Corp.
Forintek Canada Corporation *
Georgia-Pacific Corpoiation
International Paper Company
Longview Fibre Company
MacMillan Bloedel Ltd.
Municipality of Metropolitan
Seattle (METRO)
Oregon State University *
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The Cooperative includes two projects: Silviculture and Wood Quality.
Project Leaders are supported by Technical Advisory Committees composed of
individuals from member organizations with specific skills and interests.
Program and study plans are prepared jointly by the Project Leaders and
Technical Advisory Committees. A Policy Committee representing all
members meets annually to review plans and accomplishments and approve
work plans and budget.
Overall program coordination is provided by the
Director, working closely with the Project Leaders and the Policy Commit­
tee Chairman.
Field work and data management are administered by the University of
Washington.
Member organizations have the option of providing personnel
to do the field work, under supervision from the Cooperative, with an
appropriate credit against contributions to the Cooperative.
Thinning and
other treatments are applied by the landowner to Cooperative specifica­
tions.
SILVICULTURE PROJECT FIELD INSTALLATIONS
Development of the field installation program began with a number of
assumptions and requirements that influenced·experimental design:
1. Primary interest is in inferences and predictions applicable over the
region.
Therefore, installations should sample the range of sites
and physiographic conditions within the coastal Douglas-fir region.
2. Installations should be designed so that they can be continued beyond
currently accepted rotation age.
3. Plots should be large enough so that (a) number of trees is suffi­
cient for reasonable estimates of diameter distributions, (b) number
of trees will allow reasonable thinning, (c) death of individual
trees or small groups of trees will not greatly influence plot
values, and (d) plot values can be considered a reasonable approxima­
tion of results attainable on an area of operationally treatable
size.
4. The design should be such that it is not unduly difficult to find suitable areas. The primary aim is to obtain data suitable for fitting regionally appli­
cable response surfaces, rather than to test statistical significance of
The need for relatively large plots,
differences at individual locations.
combined with the limited size of areas acceptably uniform in site and
stand conditions, makes replication at individual locations impractical.
Therefore, one replicate of the chosen set of treatments is established at
each location, with the closest feasible consistency in site and initial
stand conditions among plots at a location.
Three types of field installations are being established, designated Types
I, II, and III.
The Type I is the basic or " core" installation; Type II
is a simplified analog established in somewhat older stands; and Type III
is an effort to provide research and demonstration areas for the future.
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TYPE I INSTALLATIONS
The primary objectives of Type I installations are (1) to provide data to
assess the effects of wide early spacing on subsequent tr-ee and stand
growth, yield, and wood properties and value, and (2) to provide data to
assess the effects of later thinning, applied to stands having early
stocking control, on subsequent tree and stand growth, yield, and wood
properties and value. Secondary objectives are to assess the effects, in
combination with early spacing and later density control, of pruning, tree
selection during precommercial thinning, and fertilization.
Installations are established in uniformly stocked plantations (or recent­
ly respaced natural stands) on acceptably uniform sites. Present number
of stems should be in the range of 300 to 680 per acre.
The desired initial densities are achieved through systematic respacing of
existing stands rather than through planting bare ground. This will
reduce the time necessary to obtain preliminary results and will avoid
early establishment and survival problems.
Respacing must be done before
the onset of substantial competition.
Treatments
Respacing--Three initial densities are used in each installation. These
are not necessarily the same at all installations.
The initial stems per
acre (ISPA) are reduced by one-half and one-fourth by systematic removal
of the corresponding fraction of trees. These treatments will produce a
range in density from about 75 to 680 stems per acre.
No effort is made
to specify the exact number to be left in an installation, but the·
procedure ensures that a wide range of SPA is represented. The intent is
to create "pseudo plantations" that simulate plantations established with
initial numbers of stems ISPA, ISPA/2, and ISPA/4.
Thinning--Later thinnings are superimposed on the ISPA and ISPA/2 spacings
(Table 2) .
The intent is to include a minimum number of strongly con­
trasting regimes that appear appropriate to the stand conditions and some
plausible set of owner objectives.
Supplemental treatments--a subset of installations will have additional
plots with supplemental treatments of pruning, selective versus systematic
leave tree selection, and fertilization.
Field Layout
The basic plot design consists of a square 0. 5 acre measurement plot
A double buffer is provided on one side
surrounded by a 30. 5 foot buffer.
of the plot to allow for future destructive sampling, giving a total
treatment area of 1.14 acres. (Supplemental pruning plots are one-half
this size. ) Plots are located within the study area so as to minimize
between-plot variation, then treatments are randomly assigned to plots.
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Table 2.
Density control treatments for Douglas-fir and western hemlock
Type I installations.
Treatmentb
Density control regime c
ISPA/4
1
No thinning. ISPA/2
2
Minimal thinning: thin at RD55 to RD35; no further treatment. 3
No thinning. 4
Repeated thinning: thin at RDSS to RD40; second thinning at RD55 to RD40; subsequent thinnings at RD60 to RD40. 5
Minimal thinning: thin at RDSS to RD35; no further treatment. 6
No thinning. 7
Reserved.
ISPA
(Thinning regime to be defined) a ISPA - numbers of stems per acre at time of installation establishment
b Supplemental treatments of pruning, selective versus systematic leave
tree selection, and fertilization will be included in a subset of
installations for a maximum of 15 plots.
c Stand density given in terms of relative density (RD) (Curtis 1982) ,
o s
defined as ( asal area) /(average DBH) . . A numerical value of RD= 70
(RD70) corresponds approximately to "normal" stand density in yield
tables such as McArdle et al. (1961) and Curtis et al. (1982) .
Measurements at time of plot establishment for all trees include diameter
at breast height, age at breast height, total height, height to live crown
base, and evaluation of tree vigor. Measurements are taken on the 0.5
acre measurement plot only. Planned measurement interval is four years.
Our goal is to establish 24 Douglas-fir installations and 8 western
hemlock installations by 1990. Installations would be distributed over
the range of site classes (I-V) and physiographic regions defined within
the geographic scope of the Cooperative.
TYPE II INSTALLATIONS
Information on density control effects in planted stands of commercial
thinning size will not be available from Type I installations for at least
15 years.
Meanwhile, many planted stands will have reached commercial
1077
,.
thinning size.
Currently, little information exists on results of commer­
cial thinning applied to these conditions.
A limited number of installations, designated Type II, will be established
in existing plantations that are now approaching commercial thinning
Objectives are (1) to provide partial results in the near future
stage.
for a subset of the thinning treatments in the Type I installations, and
(2) to provide experience in choosing, defining, applying, and controlling
treatment regimes that will be applicable to the basic Type I installa­
The preliminary results from
tions when they reach a comparable stage.
the first objective are particularly critical given the large area of
plantations now approaching commercial thinning stage.
Type. II installations are established only in Douglas-fir plantations or
Present SPA is expected to be 200 to 450 per
respaced natural stands.
acre, with most probably in the range of 300 to 450. Average diameter
should be about 6 to 10 inches, with present RO (Curtis 1982) less than
55.
Treatments
The density control treatments for Type II installations are shown in
Table 3.
Treatments 1, 3, and 5 correspond to treatments 4, 5, and 6 in
Type I installations (Table 2) .
Treatment 2 provides a contrasting
density level for repeated thinning; while treatment 4 provides informa­
No supplementary treatments are
tion on effect of delaying thinning.
included.
Field layout and measurement schedules are the same as for Type
I installations.
Table 3. Density control treatments for Type II installations.
Treatment
Density control regime
1
Repeated thinning, high density regime: first thinning at ROSS
to R035; second thinning at ROSS to R040; subsequent thinnings
at R060 to R040.
2
Repeated thinning, low density regime: first thinning at ROSS
to R030; subsequent thinnings at R050 to R030.
3
Minimal thinning: thin at ROSS to R030; no further treatment.
4
Delayed thinning: Thin at RD65 to R035; no further treatment.
5
No thinning.
Our goal is to establish 12 installations in Douglas-fir stands by 1990.
Because of the small number of installations planned, establishment will
be confined to site classes II, III, and IV (95 ft. < site index <135 ft. ;
base age 50 years).
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TYPE III INSTALLATIONS
Installations designated Type III are being established to provide for
future studies.
These installations will be in areas scheduled for
operational planting and will include six standard initial spacing levels.
Plantation establishment should use the best available technology so that
future development of these plantations will be representative of the
best practices available today.
The objectives of Type III installations are (1) to provide plantations
suitable for future installation of research studies, (2) to provide areas
for future destructive testing of wood grown in stands with a wide range
of stand densities, (3) to provide an opportunity to assess results of the
best stand establishment practices currently available, and (4) to provide
relatively large areas for visual demonstration of spacing effects,
Treatments
Each installation is planted at six different initial spacing levels.
Target densities are approximately 100, 200, 300, 440, 680, and 1, 210
stems per acre, corresponding to average nominal spacings of 2lx21, 15xl5,
12xl2, lOxlO, 8x8, and 6x6 feet. Field Layout
Three kinds of Type III installations are planned: (1) pure Douglas-fir,
(2) pure western hemlock, and (3) a 50:50 mix of Douglas-fir and western
hemlock.
We hope to establish an approximately equal number of installa­
tions in each category, although operational realities will probably
weight the total toward Douglas-fir. The available area is subdivided into blocks of at least three acres each
in any convenient way that will provide easily relocatable boundaries and
minimum variation in site quality. Spacing levels are then randomly
allocated among the blocks. Planting follows normal operational practice except for the differences in
spacing. The average number of trees per acre (average SPA - 488) differs
little from common operational practice. The only additional costs are
those incurred in area selection and in marking the areas to be planted at
different spacings. GOALS AND STATUS
The goals mentioned previously sum to the following:
Type I installations: 32 installations with more than 300 plots in
Douglas-fir and western hemlock stands. Type II installations: 12 installations with 60 plots in Douglas-fir
stands.
Type III installations: a m n mum of 15 installations planted as pure
and mixed stands of Douglas-fir and western hemlock.
1079
These experiments are planned for a duration of about 50 years for Types I
and III, and 30 years for Type II. We do not expect that all will survive
accidents or changes in ownership. During 1986 we prepared and tested a manual of standardized field proce­
dures and developed the framework for a data base management system. Prototypes of Type I (2 installations) , Type II (2 installations) , and
Installation establishment Type III (4 installations) were established.
on a production basis is under way in 1987, with the aim of reaching our
planned number of installations in a five-year period. CONCLUSIONS
We believe that cooperative efforts such as the Stand Management Coopera­
tive are the most promising means--and perhaps the only feasible means-­
for providing a continuing source of high-quality treatment response data.
These data are n eded for construction of reliable models that can guide
owners in evaluating alternative management regimes. The costs to an
individual owner are far less than those of an independent effort, and the
range in both the conditions represented and the expected sample size is
far greater. Response from the region's land-managing organizations has
been most gratifying.
The Stand Management Cooperative is perhaps unique in g v ng emphasis to
treatment effects on wood and product quality, which we think is likely to
be as important to our future regional competitive position as is volume
production. We also believe the installation design will overcome some of
the difficulties that have plagued past long-term studies of silvicultural
regimes in the Pacific Northwest.
LITERATURE CITED
Curtis, R. O. 1982. A simple index of stand density for Douglas-fir.
Forest Science 28(1) :92-94.
Curtis, R.O., G.W. Clendenen, D.L. Reukema, and D. J. DeMars. 1982. Yield
tables for managed stands of coast Douglas-fir. USDA Forest Service
General Technical Report PNW-135. 182 p.
McArdle, R.E. , W.H. Meyer, and D. Bruce. 1961. The yield of Douglas-fir in
the Pacific Northwest. USDA Technical Bulletin No. 201. 72 p.
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