.
,.
Wood Productivity of Pacific
Northwest Douglas-Fir: Estimates from Growth-and-Yield Models
• David
W
D.
Marshall and Eric
C.
ith increases in harvest of forests
Turnblom
ment of forest management in. the Pacific ;
in tb.e Pacific N ortb.west during
Northwest has been research demonstrating
the productive potential of the abtindant
the late 1800s and early 19.00s
came a concern for future timber supplies.
Douglas-fir forests iri the region. Bulletin
. 435· trees per acr ) are compared in Table 1
for·averag regional estimates of three mod­
urally regenerated tracts of near maximum
:base), an aver ge site index for private lands
gon. By the 1970s, however, reliance on
plantations and more intensive management
stocked naturally regenerated stand, esti­
201 (McArdle et al. 1961), firs-t published in .: els developed over the past 60 years. Both
the natural stand and the plantation were
1930 and revised in 1949 and 1961, swri­
grown on a site in<;1eX. of 118 ft (50-year
marized yields from 2,052 plots in 261 nat­
Unsuccessful attempts at selective logging in
Douglas-fir (Pseudotsuga menziesii (Mirb.)
France.) and a better understanding of re­
quirements for natural regeneration led to
tb.e adoption of moderate-sized clearcuts
.
with adjacent uncut timber as a seed source
stocking in western Washington and Ore­
the need for more dependable regeneration,
the 1950s saw a shift to artificial regenera­
practices made traditional yield tables, such
as Bulletin 201, obsolete. One of the early.
forest practice regulations to insure pr!)mpt _
(Curtis et al. 1981), which included data
(Curtis and Carey 1996). As a response of
tion methods -and the establishment of state
growth models for Douglas-fir was ·DFSIM
reforestation. This eliminated the need for
leaving onsite seed sources, making fUrther
the 1960s and 1970s, research improved the
·
ual trees (e.g:, wood qUality) and the need to
individual tree models, such as the various
led to the creation and widespread use of
stands 35 to 38 years after harvest at seven
loc;:ations in the Cascades of Oregon and
Washington and found_ 40 percent more
volume per acre and an 8 percent greater
average diameter in the planted stands. The
authors attributed the volume differential to
differences in the pattern of stand develop­
ment, e.g., planted stands. reached breast
height an average of 3 years sooner.·
An important factor in the develop­
·
dicts a-merchantable v lume of 6,035 ft3/­
similar to the one fo d by Miller· and others
(1993), it was develC?ped with data collected
trol of competing vegetation. Miller and
urally regenerated and planted Douglas-fir
diameter inside bark) of 4,150 fr/acre for
the 1930s, whereas the DF IM model pre:­
allows for thinning and fertilization. By the
1990s, the need for information on individ­
project development of mixed-species stands
others -(1993) compared paired plots in nat­
mates a merchantable volume (6-inch top
from 1,434 research plots at 203 inst3lla­
tions in the region. This model projects
priate trees for individual sites, better nurs­
ery practices, site preparation, and early con­
in western Ore,gori and Washington.
Bulle n 201, - hich assumes ·a well­
acre· for a plantation of the 1960s and early
growth in natural and planted stands and
increas'es in cut unit_ size possible. Through
quality and. survival of planted seedlings
through the selection of genetically appro­
Yields at age 45 for a well-stocked nat­
ural stand or a plantation (begun by planting
variants ·of FVS (Donnelly 1997) and
ORGANON (Hann 2003).
Each of these models represents a step
in advancing our understanding of the pro­
ductivity of coastal Douglas-fir forests and in'
the ability to· incorporate the imp ct of more
intensive management treatments in yield
assessments. Although each model takes a.
different approach and uses different data,
!1:-ey provide a means for estimating the im­
pacts of evolving ·stand management prac­
tices on yi d.
1970s. Although DFSIM predicts a 45 percent
inc ease. in yield over Bulletin 201, a difference
prior to 1975 3.n:d thus epresents estimates of
yields from
early
plantations in the region.
Pittman and Turnblom (.2003) used data from
the Stand Management Cooperative at the
University of Washington (which represents
66 Douglas-fir research iustallations in planta­
tions established from the 1960s until now
throughout western Washington, Oregon,
and British Cohunbia) to develop the TreeLab
model. This model.provides up-to-date yield
estimates for Douglas-fir plantations, repre­
senting II,lOre current management levels. Its
estimate of erchantable volume is 8,599 &3/ .
acre at total age 45, which is more than a two­
fold increase in the yield estimated for the nat­
ural stand by Bulletin 201 a,nd 40 percent
Journal of Forestry··· March 2005
71
· ·
Table 1. Douglas-fir yield projections to total age 45 yea s from three different models for naturally regenerated stand or planted
stands on a 118-foot (50-year breast height age)· site index.
·
Total
Trees
Stand.
Model
Bull
origin
per acre
at harvest
Basal :uea
(fr?-!ac)
Quadratic
mean dbh (in)
464
237
276
194.3
191.4
219.6
8.8
12.2
12.1
Natural
20lc
DFSIM.t
Planted
Planted
TreeLah"'
·
· .
.
Board foot
stem
volume
(.ft'/ac)
Mercha.ntable
volume (.ft'/ac)4
6,475
6,897
10,077
e
=
mean annual increment.
Bulletin 201 (McArdle et aL
4 Curtis et aL
1981.
.
MAl" (.ft'/ac/yr)
volume
(bflac)4
92
134
191
1.3,859
23,559 33,014
4,150 .
6,035
8,599
Merchantable cubic volume is to a 6-inch top diameter inside bark and board foot volUflle is Scribner in 32:foot logs to a 6-inch
top diameter inside bark.
.
"MAI
Merchantable
·
.
1961) yields were adjusted to fit the site curves of King (1966), using the methods of Cuitis (1992), because
of errors in the original.curves.
.
N X [0.00185584 X
ent Cooperative database: V
Dq is the quadratic mean diameter at breast height (inches) and H40 is average height (feet) of the 40 largest trees by diameter. Merchantable volumes were computed using the equations ofWilliamson and Curtis (1980).
•
Pittman and Turnblom 200,. Total
(Dq1· 89135669)
X
stem volumes for tree lab. were computed from an eql,U{tion develop ed from the.Stand Manage
(H401.08502379J], where N is trees per acre,
greater than estimated by DFSIM for early
establishment practices, it also represents
plantations. Much ofthis increase can be atdata from a rang of owners whose vegeta­
. tributed to thealmost20-footgreater heights tion management practicesvary in intensity.
estimated at age· 45 for current plantations It also does not represent advanced genera(i.e., a higherexhibited site index) when com­ . cion ge etics. Furthermore, this an ysis did
paredwiththe expected site index estimated
not . conside fe!tilizat on, which would
froin. ttaditioD.al natural stand-based site
make the potential for yields even greater.
curves.
With continued improvements in the genet­
The TreeLab modd estimates a maxiicS of planting stock, seedlingquality, vege­
, mum mean:umual increment (MAI) in mer­
ation management, and initial spacing
chantablecubicfeet for a siteitid.ex of118 ft of
guidelines, one can expect further gains in
221 tt3 /acre/year ataboutage70 for pl ta­
productivity in future Douglas-fir planta­
tions srudied y the SrandM
mentCo­
tions in thePacificNorthwest (Talbert an
operative, comparedwith its estimate of 191
Marshall2005).
fr /acre/year atage45. Althoughage70 is be-:
yondthe range.of thec· urrent databaseused to
Literature Cited
construct theTreeLab model, itdoessuggest
CuRTIS, R.O. 1992. A new look at an old ques­
that a harvest atage45 wouldcaptureabout85
tion-Douglas-fir culmination age. West.
percent of total merchantableyield measured
J. Appl. For. 7(4):97-99.
KING, J .E. 1966. Site index curves for Douglas-fir
in the Pacific Northwest. Weyerhaeuser For­
estry Paper No.8.Weyerhaeuser ForeStry Re­
search Center, Centralia, WA. 49 p.
McARDLE, R.E., W.H.
AND D. BRUCE.
1961. The yidd of Douglas fir in the acific
Northwest. USDA For. Serv, Tech. Bull. No.
·
in cubic feet
consistentwith the growth pat7 t nsof Douglas-fir,
whichreach peak average r
atively lateage. For mparison,
growth ta el
the TreeLabmodel predicts MAis of 93 and
243 ft3 /acre/year at age45 for a lower site(93
ft) andhigh site(143 ft) stand, respectively. Although some ·of the differences in these comparisons are due to the differences in data sets, modeling techniques, and the
assumptions made(e.g., the resulting stock­
ing from natural regeneration is highly va.d-'
able and can impact future yields), they
demonstrate the .gains in potential wood
production achieved overthe past60 years
in managing coastalDouglas-fir stands. Al­
though theTreeLab model is based on the
most current data sets and represents plan­
tations of improved seed and more intensive
(rev.). 74 p.
M.niER., R.E., R.E.' BIGLEY,
.201
AND S. WEBSTER.
.
1993..Early development of matched planted
and naturally regenerated Douglas-fir stands
. CURTIS, R.O., AND AB. CAREY.· 1996. Timber
Supply in thePacific Northwest:Managing for
economic and ecological values in Douglas-fir
. forest. J. For. 94(9):4 -7, 35:...37,
CURTI$, R.O.
G.W. CLENDENEN, D.L. RE­
UKEMA, AND D .J. DEMARs. 1981. A new stand
simulator for coastal Douglas-fir. DFSIM us­
.
Journal of Forestry·
•
March 2005
after slash burning in the Cascade Ran
.
West. J. Appl. For.' 8(1):5-10.
PITTMAN, S.D., AND E.C. TURNBLOM. 2003. A
er's guide. USDA For. Serv. Gen. Tech. Rep.
PNW-128. 79 p.
srudy of self-th.inniitg using coupled allometric
equations: implications for coastal Douglas-fir
srand dynamics.
Can. J.
For. Res. 33:1Q61­
1669. Available online atwww.cfr.washington.
edu/ research.smc/treelab/Webs'ite/TreeLab
_home:htm. Last accessed February 23, 2005.
TALBERT, C., AND D. MARsHALL. 2005. Planta­
tion productivity in the Dotiglas-:6r region un­
der in:tensive silvicilltural practices: Result
. from rese3:fch and operations.
J.
For. 103'{2):
.
. ·67-72.
WILLIAMSON, R.L., AND R.O. CURTIS. 1980. Es­
timating merd?.antable volumes of second
growth Douglas-fir stands fro,m total cubic
volume and associated stand characteristics.
USDA For. erv.
Res;
·
Note PNW-353. 14 p.
DONNELLY, D .M. 1997.Pacific Northwest Coast
variant of the Forest Vegetation Simulator
USDA Forest Service, Forest Managenient
Service Center, Foq Collins, CO. Available
online at WWW'.fs.fed.us/fmsdfvs/index.php.
Last accessed August 2004.
HANN, D.W. 2003. ORGANON user's manual:
Edition 7.
Department of Forest Resources,
Oregon State University, Corvalli, OR.Avail­
ableonlineatwww.cof.orst.edu/cof/fr/research/
organon/. Last aci:essed August 2004.
About this file: This file was created by scanning the printed publication.
software have been corrected; however, some mistakes may remain.
72
=
·
David D. Marshall {dmarshall@fi.jed.us) is
research forester, US For:est Seroice, Olympia
F rest Sciences Laboratory, Olympia, WA ·
98 12-!(193, and Eric C. Turnblom
(ect@u. washington.edu} is associate professor,
Forest Biometrics, College ofForest Resources,
University ofWashington, Seattle, Washing­
ton 98195-2100.
Misscans identified by the
Journal of Volume 103, Number
March 2005 57
2
Commentary: Growing Better All the Time
M T. Goergen Jr.
57
Letters
61 Intensively Managed Forest Plantations in the Pacific Northwest: Introduction
W. T. Adams, S. Hobbs, and N johnson
63 ·
Global Persf>ectives on Intensively Managed Plantations: Implications for the Pacific
Northwest
C.S. Binkley, M.E. Aronow, C.L. W hburn, and D.
67 !few.
Plantation Productivity in the Douglas-Fir Region Under Intensive Silvicl.lltural
Practices: Results from Research and Operations
C. Talbert and D. Marshall
73 Wood Productivity of Pacific Northwest Douglas-Fir: Estimate from Growth-and­
Yield Models
D.D. Marshall and E. C. Turnblom
75 Uneven-Aged Management: Panacea, Viable Alternative, or Component of a Grander Strategy? D. Maguire
77 Assessing Wood Characteristics and Wood Quality in Intensively Managed Plantations
B. L. Gartner
80 Economics of Intensively Managed Forest Plantations in the Pacific Northwest .
G.E Muryhy, W.RJ Sutton, D. Hill, C. Chambers, D. CreeL C. Binkley, and D. New
85 Environmental Consequences of Intensively Managed Forest Plantations in the Pacific Northwest JP.
90 f!ayes, S.H Schoenholtz, M]. Hartley,
G. Murphy, RF. Powers, D. Berg, and S.R Radosevich
Lessons From Intensive Agriculture
P.L. Kirschenmann
92 Public Influences on Plantation Forestry
G. T. Howe, B. Shindler, B. Cashore, E Hansen, D. Lach, and W. Armstrong
97 A· Conservation Advocate's Perspective on Intensively Managed Forest Plantations
c. Willer
99 (Over)Stories: Examining the Philosophical Assumptions Behind Intensively Managed Forest Plantations KD.Moore
101
lntensiv ly Managed Forest Plantations in the Pacific Northwest: Conclusions
W. T. Adams, S. Hobbs, and N Johnson
103 Perspective: Telling Our "Story"
J Coufal