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BRINGING TIMBER QUALITY CONSIDERATIONS INTO FOREST MANAGEMENT DECISIONS: A CONCEPTUAL APPROACH Roger D. Fight, Thomas A. Snellgrove, Robert 0. Curtis, and Dean S. DeBell
Until recently, development of the timber industry in the
Douglas-fir region was based on the availability of large vol­
umes of "old growth." Large volumes per acre and large trees
meant low logging and milling costs per unit of volume.
Large, old trees grown slowly in dense stands produced a high
proportion of wood with narrow and uniform growth rings and
relatively few knots. The highly desirable appearance,
strength, stability, and machining properties of such wood
have established and maintained this region in a strong position
in domestic and international markets for logs, lumber, and
plywood.
The timber resource is now far along in the transition from
unmanaged forests to extensively managed "young grqwth."
It will soon be composed of more intensively managed planta­
tions that have been under some degree of control from the
time of establishment. Wood from these new stands will have
characteristics very different from wood from the old-growth
forest, and the way these stands are managed will affect these
characteristics. Any of a wide range of possible management
regimes can be imposed on these new stands; and these re­
gimes will affect the characteristics of the wood produced, its
value, and its suitability for different products and markets.
The relative importance of these changes can most appropri­
ately be judged by putting them in a monetary context.
Studies on wood quality for Douglas-fir (Pseudotsuga men­
ziesii [Mirb.] Franco var. menziesii) have been conducted for
years, but the researc has several shortcomings. The first and
most fundamental is that there are no examples of the wood
grown over a rotation in stands grown under a wide range of
silvicultural regimes. Practices such as fertilization and wide
initial spacing have been introduced too recently to provide
good information on their ultimate effects, and recent and cur­
rent practices by no means represent the full range of regimes
that could be applied. Second, little has been done to assess
effects in monetary terms. Third, the work has not been incor­
porated into a comprehensive analysis. It is known that silvi­
cultural decisions affect timber yields and costs of manage­
ment, logging, and manufacturing, as well as wood quality and
20
product yield. It is important, therefore, to have a "holistic"
analysis that looks at effects on costs and returns in timber pro­
duction, logging, and manufacturing.
This paper illustrates the possible magnitude of the changes
in product quality and value, describes what is needed in a hol­
istic analysis, and suggests how to deal with an uncertain fu­
ture. It concludes by citing some of the overly simplistic solu­
tions that can be avoided by using a holistic analysis.
AN ILLUSTRATIVE STUDY
Information now available on relationships between product
value. and wood quality or tree size comes mainly from experi­
·ence with natural stands. These relationships may be quite dif­
ferent for future managed stands, which have been under
stocking control from the time of establishment. Relationships
will also be different for stands grown under different manage­
ment regimes. The potential effect of different regimes on
product quality and value is illustrated using results of a slash
pine (Pinus elliottii Engelm.) study. Comparable studies for
Douglas-fir are not readily available. This study is used to
point out the potential losses in yields and quality of products
that may be associated with highly accelerated growth. These
results do not, however, address the overall economics of the
issue, which must consider the effects of revenues, costs, and
interest rates.
This study compared the quality and yields of mill run lum­
ber from a conservatively managed slash pine stand (hereafter
referred to as the "control") with that of lumber from a rapidly
grown ("test") stand. The study was conducted at the School
of Forestry, Stephen F. Austin State University (Burkhart et al.
1984). Results indicate that there may be marked and undesir­
able changes in the properties of lumber from rapidly grown
slash pine compared with that from denser, conservatively
thinned stands. Much of the lumber manufactured from the
rapidly grown trees did not meet current standards for struc­
tural grade material.
The study used samples of 25 trees from each of two planta­
tions on similar sites in eastern Texas. Pertinent information on
the sample is given in Table l. The test trees had been planted
at 12 by 12 foot (3. 7 by 3. 7 m) spacing (300 trees/acre or 74 1/
ha) and were subsequently thinned at age 18 to 250 trees per
acre (6 18/ha). The 25 test sample trees were cut at age 20. The
control trees were planted at 6 by 6 foot ( l . 8 by l .8 m) spacing
( 1,200 trees/acre or 2,965/ha). Subsequent thinnings at ages
12, 20, 25, and 35 years reduced the stand to 245 trees per acre
(605/ha) at age 35. The stand was thinned again to a basal area
of 85 to 90 square feet per acre ( 19.5 to 20.7 m2/ha) at age 48.
The 25 control sample trees had similar dbh to the test trees
from the first plantation, and were cut at age 50.
The effects of these two contrasting regimes on average tree
volume, percentage of volume suitable for sawlogs, and per­
centage of volume in juvenile wood are shown in Table 2. The
test trees had more crooked tops and lower specific gravity
than the control trees. The test trees produced logs with high
taper, one or two rings per inch (0.4 to 0.8 ring/em), and a
substantial amount of juvenile wood.
All logs were processed into 1 and 2 inch lumber through a
profiling, chipping headrig. The lumber was then kiln dried
and planed following conventional practice. All lumber was
graded visually according to the current standards of the South­
em Pine Inspection Bureau. Subsequently, a subsample of the
boards were tested for stiffness (modulus of elasticity) and
bending strength (modulus of rupture) to provide some mea­
sure of how this lumber meets performance standards. .
Because the control trees were taller, they produced more
sawlogs per tree. To facilitate comparisons of recovery be­
tween the two samples, only the top log and butt log from each
tree were used. Recovery was compared on three bases: ( l )
proportion o f the log recovered as lumber, (2) the average
quality and value of the lumber, and (3) the average value of
the log (which combines the effects of items 1 and 2).
Lumber recovery factor (the nominal board feet of lumber
per cubic foot of log) was used to compare the proportion of
the log recovered as lumber (Table 3). Less lumber per cubic
foot of log was recovered fro the test sample because the
trees had higher taper and more crooked logs.
TABLE 4. TABLE 1. Tree measurements of slash pine in eastern
Texas for test and control regimes
(twenty-five trees each regime).
50=year
Average
Average
Dbh
Site
Index
Age
Height
(yrs)
Regime
(in.)
(em)
(ft)
(m)
Test
14.5
36.8
72
21.9
20
105
Control
15.1
38.4
105
32.0
50
105
TABLE 2.
Comparison of test and control slash pine
trees in eastern Texas.
Juvenile
Sawlog
Average
Volume as a
Tree Volume
Percentage of
Wood as a
Percentage of
Sawlog Volume**
(ft3)
(m3)
Tree Volume*
Test
26.5
0.75
77
55
Control
47.0
1.33
87
16
Regime
*Based on a 4 inch (10.2 em) top.
**Calculated on the assumption that the first ten rings
from pith are juvenile wood,
TABLE 3,
Lumber recovery of the slash pine logs.
Control
Test
(board feet/ft3)
%
Reduction
Butt.logs
6,3
5,0
21
Top logs
6.7
5.8
13
The quality of timber could be expressed as percentage of
lumber recovery by grade, but a more useful index of quality
for this study is the average value of the lumber produced, in
U.S. dollars per thousand board feet. The average value is cal­
culated by multiplying market prices for lumber by grade by
the amount produced in each grade. Table 4 shows the percent­
age of No. 2 and Better lumber recovered and the average
value of all the lumber produced.
Percentage of No. 2 and Better lumber recovered and average value of lumber produced from slash pine
trees in eastern Texas.
Average Value
No. 2
of Lumber*
and Better
Logs
Control
Test
Reduction
'
(percent)
Butt logs
Top logs
70
64
47
28
Control
Test
%
Reduction
($U.S, /MBF)
33
230
196
15
56
200
175
12
*Based on lumber prices from Temple-EasTex for September 24, 1982,
Timber Quality Considerations
21
No. 2 and Better grade is the most common grade used in
residential construction, and the proportion of No. 2 and Better
recovered is therefore a good index of how well the resource quality meets the current market demands for housing. The re­
duction in the percentage recovery of No. 2 and Better between
the control and test (Table 4) was partly offset by gains in
lower grades, evident by the smaller reduction in the average
value of all lumber produced.
The product value per cubic foot of log combines the effect
of product volume and quality. In Table 5, product value is
expressed in dollars (U.S.) per cunit (100 cubic feet). Based on
current markets and visual grading of lumber, a mill sawing
200 cunits (566 m3) of logs per day would recover about
$10,000 (U.S.) per day less in lumber from the test trees than
from the control. Again, this does not consider the economics
of rotation length.
These comparisons of product volumes and values do not
fully express the differences in lumber quality. The lumber
grades commonly used are based on visual inspection of the
piece and were developed for timber grown in natural stands;
they may not be indicative of lumber quality of wood grown in
the future under radically different conditions. Two common
measures of performance of wood are extreme fiber strength
(modulus of rupture, MOR) and stiffness (modulus of elas­
ticity, MOE). Most structural uses of lumber depend, in part,
on these two measures. Grades of lumber assigned after visual
inspection are supposed to meet certain published requirements
for strength and stiffness (design criteria). Table 6 compares
lumber from the control and test samples in terms of these
strength and stiffness requirements. Although much of the
lumber from rapidly grown trees sampled in this study may
meet the published requirements for strength, only a small per­
centage will meet the requirements for stiffness. Stiffness is a
critical factor, however, because in most wooden structures se­
rious problems arise from bending long before breakage oc­
curs. The consequences of such problems could be disastrous
in terms of product liability if these differences were to go un­
recognized. When recognized, their importance will be re­
flected in the value of products. The previous tabulation
showed that log values were one-fourth to one-third less for the
fast grown material; these values would be reduced even more
if the lumber was graded to meet the design criteria.
How well this example will fit Douglas-fir is not known.
The study was based on slash pine, and it was a relatively
small sample from only one geographic area. Nevertheless, the
known differences in wood properties between juvenile wood
and mature wood in Douglas-fir, and the fact that juvenile ,
wood is produced over a longer time span in Douglas-fir,
strongly suggest that similar effects will occur. Whether the
magnitudes will be more or less cannot be determined without
similar recovery studies for Douglas-fir. Such studies should
be conducted to assess effects on the full array of potential .
22
Fight, Snellgrove, Curtis, DeBell
TABLE 5.
Product value of the slash pine logs,
Test
Control
$U. s . I
cunit $U. s. I
$U. s. I
m3
cunit
$U. s . I
%
m3
Reduction
Butt logs
146
52
98
35
33
Top logs
134
47
102
36
24
Cunit
•
100 cubic feet,
TABLE 6. Percentage of No,
2 and No, 3 grade lumber
from the control and test slash pine trees
from eastern Texas meeting strength and
stiffness requirements,
No. 3
No. 2
Logs
Stiffness
Strength
Stiffness
100
100
100
100
100
100
100
100
100
19
100
19
77
8
96
9
Strength
Control:
Butt logs
Top logs
Test:
Butt logs
Top logs
products for trees grown under a range of management re­
gimes.
The'.above example illustrate negative effects of one set of
management practices. Some practices, such as pruning, will
have positive effects and will improve wood quality. A recov­
ery study of Douglas-fir trees that had been pruned about
thirty-five years before (Cahill et al., this volume) showed
about twice as much select grade lumber and over three times
as much high grade veneer as was recovered from an unpruned
"control" sample.
REQUIREMENTS OF A
HOLISTIC TIMBER ANALYSIS
In broad terms, a holistic analysis should include everything
that affects either costs or returns in timber management, log­
ging, transportation, manufacturing, and marketing. Note the
limitation that this is a holistic "timber" analysis. Many other
considerations besides the financial return to timber production
go into silvicultural decisions. it is important, however, to un­
derstand the timber values and implications before trade-offs
with other values can be reasonably considered. The SILMOD
model (Sutton 1984) developed for radiata pine (Pinus radiata)
in New Zealand is an example of a holistic timber analysis.
Although this approach may have been done by some corpora­
tions, it has not as yet been used to guide management deci­
sions on public forests or on the majority of private forests in
North America. Figure 1 shows the more important compo­
nents of a holistic analysis of silvicultural regimes. Necessary
components for a holistic analysis are discussed below.
GROWTH AND YIELD '
EVALUATION MANAGEMENT I..
COST OF SILVICULTURAL -
LOGGING COST REGIMES NET VALUE OF PRODUCTS Figure 1. Important components of a holistic analysis of silvicultural regimes.
Growth and Yield
Yield information for coast Douglas-fir is available from
published sources and stand simulators such as DFSIM (Curtis
et al. 1981, 1982), DFIT (Bruce et al. 1977), TASS (Mitchell
and Cameron 1985), and SPS (Arney 1985), as well as from
various proprietary models. From the standpoint of a holistic
analysis, the concern with these models is that they provide
little beyond volume and diameter that can be used to deter­
mine product potential. Furthermore, the relationships of tree
size to product yields and values that would be used in con­
junction with these models are based primarily on natural
stands, and many of them may not be applicable to the man­
aged stands of the near future.
Other tree characteristics that may affect product quality and
value and that can be manipulated by silvicultural practices in­
clude the proportion of juvenile wood, specific gravity, ring
width, ring width uniformity, knot size and kind (live versus
loose), bole taper, and live crown length. All these attributes
are potentially predictable using existing modeling methodol­
ogy.
Management Costs
Management costs are probably the least troublesome data
needs. The biggest management costs are those that occur with
stand establishment and early spacing control. These costs are
being incurred today, and records from current management
provide a good basis for the data needed. Records are also
available on other commonly used silvicultural practices such
as fertilization.
Logging Costs
Current logging costs for coast Douglas-fir are available on
a piecemeal basis from a variety of sources. Logging cost rela­
tionships for young-growth coast Douglas-fir that have been
developed specifically to meet silvicultural planning needs are
available in Fight et al. (1984). Harvesting of stands now being
established or treated, however, is far enough in the future that
changes will probably occur in cost relationships associated
with the developments of technology for logging small trees.
The critical need in logging cost information is that it properly
account for the effect of diameter and volume harvested per
entry, because these variables significantly influence logging
costs and are significantly affected by silvicultural decisions.
Product Value
The area most deficient of necessary information for a holis­
tic analysis is in the determination of the net value of products.
Figure 2 outlines information needed. An estimate is needed
for the value of products and the cost of manufacturing trees
from managed stands when those trees are allocated to prod­
ucts, bucked, and processed. The difference between value of
products and cost of manufacturing is the net value. If net
product value can be determined from trees with different char­
acteristics that will be produced in managed stands, the results
can be used to develop.relationships between net value and tree
characteristics; these relationships can then be used in a holis­
tic analysis of silvicultural regimes.
Several problems will occur in developing the net value rela­
. tionships. As with logging, the manufacture of products will
TREES FROM MANAGED STANDS I
ALLOCATE LOGS TO PRODUCTS I
I
I
VALUE OF COST OF PRODUCTS MANUFACTURING I
I
I
NET VALUE OF PRODUCTS Figure 2. Infonnation needed to detennine net value of products.
Timber Quality Considerations
23
occur far enough in the future that changes in technology will
change manufacturing costs and even product lines. Further­
more, current information on manufacturing cost is generally
regarded as proprietary and is not readily available. The criti­
cal need for information on manufacturing costs is that it prop­
erly reflect the effect of log size.
Appropriate grade and yield recovery also poses a serious
problem. Although numerous mill recovery studies have been
conducted for Douglas-fir (Ernst and Fahey, this volume), vir­
tually all of the studies are for extensively managed stands
grown under "natural" conditions. Results of these studies
will not be representative of the trees grown under intensive
management. The authors know of no studies to determine re­
covery from the range of tree descriptions that will be repre­
sented in future managed stands; yet the slash pine example
shows that management can have dramatic effects. Further­
more, the Douglas-fir studies deal with only a few of the tree
characteristics that are influenced by silvicultural regimes. In
those studies, size of trees has been used as a surrogate vari­
able for a number of quality-related characteristics. In man­
aged stands those characteristics will become more important
and will not necessarily be correlated with size.
A final problem will occur in developing product prices that
are relevant to future markets. Various econometric models
might be used to get projections of timber prices. These mod­
els only project prices for some unspecified mix of volume of
products by grade. Relative prices for different grades may
change dramatically as a result of changes in the abundance of
and demand for lower grade and higher grade material. Fur­
thermore, these econometric models cannot be expected to be
very successful in anticipating the effect of technological
change on relative prices.
UNCERTAINTY IN SILVICULTURAL PLANNING
Because of the need to relate silvicultural decisions to
prices, costs, and technological change, any analysis necessar­
ily involves numerous and uncertain assumptions. Many in­
vestment analyses ha:ve dealt with uncertainty by ignoring it.
The danger in ignoring it is that the analyst may develop a sil­
vicultural strategy that is rigidly tied to a particular view of the
future; this strategy may prove very costly under other reason­
able scenarios.
A safer way to deal with uncertainty is to do extensive sensi­
tivity analysis. The approach to sensitivity analysis that seems
most relevant to silvicultural planning proceeds as follows..
First, develop alternative futures that are internally consistent.
Internal consistency requires, for example, that the cost and
price assumptions be based on the same set of broad economic
assumptions about wages, economic gr<?wth, and price infla­
tion. Broad professional participation is important to ensure
24
Fight, Snellgrove, Curtis, DeBell
that relevant trends are recognized and that the alternative fu­
tures are internally consistent. The next step is to translate
these alternative futures into sets of assumptions needed for the
analysis. The analysis is repeated for each alternative future.
The "best" strategy is developed by the same subjective deci­
sion process that has always been used, but with a better under­
standing of the range of outcomes that can be anticipated from
alternative strategies. One consideration should be how much
flexibility is provided by a particular strategy to shift to another
strategy if in midrotation there are major unanticipated changes
in technology or markets. An illustration of the approach pro­
posed here is discussed in another paper in this volume (Fight
and Briggs).
CONCLUSIONS
There are several ways one could err badly in developing
management strategies for coast Douglas-fir. Failure to recog­
nize how product yield and value may be affected by silvicul­
tural decisions may result in an overly simplistic solution such
as ''maximize volume production and let technology take care
of quality problems.'' It may be true that if enough Douglas-fir
of similar characteristics is produced, technology will find a
use for it. It is also very likely that the market will impose a
penalty by paying a premium to those who produce wood that
is better suited to meeting the needs of timber products manu­
facturers.
Failure to evaluate the monetary consequences of silvicul­
tural decisions on wood quality may result in an overly sim­
plistic solution such as "minimize the amount of juvenile
wood that is produced.'' Juvenile wood does have undesirable
properties for many uses, but it is unlikely that minimizing ju­
venile wood is the most cost-effective means of managing the
''juvenile wood problem.''
Failure to consider alternative futures and how technology
might change cost relationships in manufacturing and logging
may result in an overly simplistic solution such as ''grow
Douglas-fir on all sites to a specified target'size." It is unlikely
that requirements in manufacturing are so rigid that the advan­
tages of a common tree size would outweigh all other consider­
ations in all circumstances.
The examples above may seem overly simplified, but most
of these "solutions" have been discussed before. The organi­
zational structure of corporations and public agencies and the
difficulties of interdisciplinary communication often lead to
tunnel vision and to solutions like these that are much less than
optimum.
Forest managers need to recognize that there are no right or
wrong answers; there are simply various management strate­
gies with different probabilities of success. All the issues being
addressed in this volume have a role in helping make a better
estimate of the most desirable management strategy. A holistic
analysis offers strong hope of identifying the key issues and
focusing that information in a way that will give the forest
manager the best possible information of what strategy to pur­
sue.
doches. Texas. 16 p.
Curtis, R. 0., G. W. Clendenen, and D. J. DeMars. 1981. A new stand simu­
lator for coast Douglas-fir: DFSIM user's guide. USDA For. Serv. Gen.
Tech. Rep. PNW-128. Pac. Northwest For. and Range Exp. Stn., Port­
land, Oregon. 79 p.
Curtis, R. 0., G. W. Clendenen, D. L. Reukema, and D. L. DeMars.
1982. Yield tables for managed stands of coast Douglas-fir. USDA For.
Serv. Gen. Tech. Rep. PNW-135. Pac. Northwest For. and Range Exp.
Stn., Portland, Oregon. 182 p.
REFERENCES
Fight, R. D., C. B. LeDoux, and T. L. Ortman. 1984. Logging costs for man­
agement planning for young-growth coast Douglas-fir. USDA For. Serv.
Gen. Tech. Rep. PNW-176. Pac. Northwest For. and Range Exp. Stn.,
Arney, J. D. 1985. A modeling strategy for the growth projection of managed
Portland, Oregon. 10 p.
stands. Can. J. For. Res. 15:511-518.
Bruce, D., D. J. DeMars, and D. L. Reukema. 1977. Douglas-fir managed
Mitchell, K. J., and I. R. Cameron. 1985. Managed stand yield tables for
yield simulator: DFIT user's guide. USDA For. Serv. Gen. Tech. Rep.
coastal Douglas-fir: Initial density and precommercial thinning. Land
Manage. Rep. 31. Ministry of Forests, British Columbia. 69 p.
PNW-57. Pac. Northwest For. and Range Exp. Stn., Portland, Oregon. 26
Sutton, W. R. J. 1984. New Zealand experience with radiata pine. The H. R.
p.
Burkhart, L. F., M. D. MacPeak, and D. Weldon. 1984. Quality and yield of
lumber produced from fast growth, short rotation slash pine: A mill study.
MacMillan Lectureship in Forestry. University of British Columbia, Van­
couver. 21 p.
Unpublished report. On file at Stephen F. Austin State University, Nacog-
1986.
In:
Oliver, Chadwick Dearing; Hanley,
Donald P.; Johnson, Jay A., eds. Douglas-fir:
stand management for the future: Proceedings
of a symposium;
1985 June 18-20; Seattle, WA.
Contribution no. 55. Seattle: College. of
Forest Resources, University of Washington.
Reproduced by USDA Forest Service,
for official use.
Timber Quality Considerations
25