Logging utilization Montana, 1988

14 Pages·1992·0.82 MB·English

by  McLain, William H

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United States Logging
Department Utilization
ofAgriculture
Forest Service Montana, 1988
Intermountain
Research Station
Resource Bulletin
INT-78 William H. McLain
THE AUTHOR RESEARCH SUMMARY
WILLIAM H. MCLAIN is a forester in the Interior Data collected on 25 logging operations in Montana
West Resource Inventory, Monitoring, and Evalua- in 1988 provided board-foot/cubic-foot conversion fac-
tion Program at the Intermountain Research Station. tors of log scale and factors to apply to harvestvolume
His primary area of responsibility is inventory and estimates to obtain removals estimates. The compo-
special projects. He holds a B.S. degree in forestry nents of timber products and removals, obtained by
from Oklahoma State University, Stillwater, OK, and application of these factors to the 1988 Montana timber
has done graduate work in economics at Weber State harvest, are included. Additional findings presented
in
University, Ogden, UT. He began his Forest Service table form are the diameterdistribution oftrees removed
career in 1968 with the Intermountain Station. from growing stock per thousand cubic feet of products
and the volume of logging residue in pieces 6 feet and
longer as a proportion of product volume. Survey meth-
ods and estimates of data reliability are also presented.
®
Printed on recycled paper
Intermountain Research Station
324 25th Street
Ogden, UT84401
—
Logging
Utilization
Montana, 1988
William H. McLain
INTRODUCTION
operations were estimated to provide sufficient data
to achieve a standard error ofthe ratio ofless than
A study relatingMontana's timber harvest to the 20 percent. Further, "large" mills were estimated
forestinventorywas conducted concurrentlywith the to receive about 90 percent ofthe timber production,
statewide forest inventory in 1988-89. with 42 percent ofthe harvest estimated to occur
Two other concurrent studies, timber product out- on National Forests. In planning, 20 samples were
put (McLain and others in preparation) and fuelwood distributed as close to these estimates as possible.
harvest (McLain 1990), provided estimates oflog vol- However, field crews are sometimes forced to meas-
umes harvested and delivered to primary wood pro- ure operations that are available, whether or not
cessors and to residences burning firewood. they fit the stratification scheme. In Montana, they
Logging utilization, the subject ofthis bulletin, pro- measured 25 operations, rather than 20, to obtain
vides the factors to convert reported harvest volumes minimum total log volume. The data were collected
received by primary wood processors into cubic feet as follows: 80 percent ofthe operations sampled were
and removals estimates. sending the logs to large mills and 64 percent ofthe
Additional factors, also to be applied to harvest vol- operations measured were on National Forest land
umes, provide estimates ofthe diameter class distri- (table 1).
bution ofthe harvest and ofthe volume ofresidue in
pieces 6 feet and longer.
Data Collection
STUDY METHODS The study design prescribed four basic measure-
ments to be obtained from each sample unit to com-
The study was conducted in Montana using the pute removals and logging residue factors.
samplingandmeasurement techniques designedby On each sample unit, 12 to 21 felled and bucked
A. K. Wilson ofthe Forest Survey Project at the In- producttrees with an average sample unittotal gross
termountain Station from 1959 to 60 (Wilson 1965). volume ofabout 2,900board feet(International 74-inch
rule) and a varyingnumber ofassociated nonproduct
Sample Size and Distribution trees were measured to obtain:
Measurements were obtainedinthe summerof1988 1. Product volume
on active sawlogandmultiproductloggingoperations 2. Noninventory volume in products
located on timberland. These operations—the basic 3. Volume oflogging residue from product trees
sample units—were distributedthroughoutthe State. 4. Volume ofloggingresidue from nonproducttrees
They were selected within four strata defined by All measured trees were categorized as poletimber,
land ownership and op—erator-size class. Two owner- sawtimber, salvable dead, cull, or nontimber. Gross
ship classes were used National Forest and other. and net volumes in cubic feet and board feet (Interna-
Operator-size class correspondedto the production tional 74-inch rule and Scribner rule) were obtained
class ofthe wood processing plant recei—ving the har- by scaling. These measurements were correlated to
vested logs. Two size classes were used small, those obtain factors to apply to reported product volumes
consuming less than 10 million board feet peryear, received by primary wood processors. Thus, all fac-
andlarge, those consuming 10 millionboardfeet and tors were calculated as proportions ofproduct vol-
more peryear. ume. No productvolume from culltrees ornontimber
Sample size was calculated to achieve a standard species was encountered on the logging operations
error ofthe logging residue ratio (total net cubic-foot sampled.
volume oflogging residue divided by the total net vol-
ume oftimber products) ofnot more than plus or STUDY RESULTS
minus 20 percent.
The samples were distributedthroughout the strata The results ofthis study compare cubic-foot/board-
in proportion to the estimated harvest volume occur- foot conversion factors, removals factors, removals
ringin each stratum. Measurements from 20 logging
1
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Table 1 Numberof logging operations measured in each the conversion offorest land to nonforestuses, for
stratum, Montana, 1988 instance, would otherwise be considered a removal.
Factors are used to estimate the amount ofgrowing-
Ownergroup stock or sawtimber volume in the products and the
Stratum National Forest Other Total amount oflogging residue associated with the prod-
Numberofoperations measured- uct volume. Removals is the sum ofthese volumes
Mill size: (fig. 1).
Small 5 5 The growing-stock removals factor of1.121 means
Large 11 9 20 that for every 100 cubic feet oflogs from growing-
stocktrees harvested in Montana (table 3):
Total 16 9 25
112.1 cubic feet were removed from the growing-
stockinventory
99.9 cubic feet ofremovals were in the logs
volumes, loggingresidue volume in long pieces, and 12.2 cubic feet ofremovals were residue
the diameter class distribution oftrees harvested in 8.9 cubic feet ofresidue came from
1988 on logging operations in Montana. some ofthe trees producingthe 100
cubic feet oflogs
Log Scale Conversions 3.3 cubic feet ofresidue were in trees
knocked over while loggingthe 100
The following product volumes resulted from scal-
cubic feet
ingthe logs ofthe 386 producttrees onthe 25 logging
operations measured. And 0.1 cubic foot ofthe 100 cubic feet was not
growing-stockremovals. It came from stumps and
Product volume
tops.
Gross Net
For every 100 cubic feet oflogs from salvable dead
Cubic 12,018 11,873
trees harvested in Montana:
Board feet, Scribner rule 63,790 62,650
Board feet, International 3.3 cubic feet ofresidue were produced intrees
V4-inch rule 74,725 73,625 knocked overwhile logging
The conversions appearing in table 2 were calcu- The sawtimber removals factor of0.986 means
lated using the net product volumes. These conver- that for every 100 board feet (Scribner) oflogs from
sions are statewide averages, reflectingthe average growing-stocktrees harvestedin Montana:
conversionforthe harvestofthe productmix encoun- 98.6 boardfeetwere removedfrom the sawtimber
tered on the 25 operations measured. Cautionis rec- inventory
ommended in applyingthese factors to State subdi- 95.1 board feet ofsawtimber removals were
visions orto harvests ofa narrow range ofproducts in the logs
ofsmall size, such as posts orfuelwood, orto sawlogs 3.5 board feet ofsawtimberremovals were
ofexceptionallylarge diameters (see table 7). residue
3.4 board feet ofresidue came from
Removals Factors, Montana, 1988 some ofthe trees producingthe
95.1 board feet ofremovals inthe
The factors in table 3 are applied to reported har- logs
vest volumes to estimate growing-stock and sawtim- 0.1 board foot ofresidue was in trees
ber removals from the inventory bylogging. In this knocked over while logging
publication "removals" is limitedto harvesting. The
normal definition ofremovals includes other forms; And 4.9 ofthe 100 board feet were not sawtimber re-
movals; this volume came from poletimber andthe
tops and stumps ofsawtimber.
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Table 2 Net productvolume conversion factors for For every 100 board feet oflogs from salvable dead
Montana, 1988 trees harvested inMontana:
1 cubic foot equals 5.2767 board feet 0.1 ofa board foot ofresidue would have been pro-
(Scribner rule) duced intrees knocked over while logging
1 cubicfoot equals 6.2010 board feet As in the case oflog scale conversions, the reader
(International 1A-inch rule) is cautioned to consider the appropriate use ofthese
1 board footequals 1.1752 board feet factors. Forinstance, harvestingoperationsinastand
(Scribner rule) (International 'A-inch rule) ofpredominantly dead timber maywell produce no
residue.
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Table 3 Removals factors in cubicand board feet, Montana, 1988
Board feet
IIInItIPvlr1nIadtIiHWoInIaQlI
Type offactor feet Scribner rule 74-inch rule
Logging residue 0.122 0.035 0.0341
Producttree residue .089 .034 .033
Nonproduct tree residue .033 .001 .002
Noninventory productvolume .001 .049 .049
Inventory productvolume .999 .951 .951
Growing-stock (cubic) or
sawtimber (board feet) removals 1.121 .986 .985
'Dueto rounding:the logging residuefactordoesnotequalthe sumoftheproducttree residue
factorandthenonproducttree residuefactor.
Sawtimber2 Tree
(at least 9.0 inches
d.b.h.)
Poletimber1 Tree
4 inches diameter
(5.0-8.9 inches
outside bark \.
d.b.h.)
Top 7 inches diameter
outside bark
4 inches diameter
outside bark
Growing-stock
volume (ft3) Sawtimber
Vvolume
f (board feet)
V Growing-stock
fvolume (ft3)
Stump
1 ft.
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Figure 1 Stem sections of a poletimberand a sawtimber tree. Inven-
tory volume comprises growing-stockvolume in poletimbertrees and
both growing-stock and sawtimber volume in sawtimbertrees. Non-
inventory volume is shaded. Roundwood products from the non-
inventory portion of tree stems is noninventory productvolume. Board-
foot volume from poletimbertrees orfrom sections of sawtimbertrees
above the 7-inch top (cross-hatched) is also noninventory productvol-
ume. 1Softwoods; hardwoods, 5.0-10.9 inches d.b.h. 2Softwoods; hard-
woods, at least 11.0 inches d.b.h.
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Removals and Products trees and nonforest land). The product volume from
growing-stock trees comprises noninventory product
Table 4 exhibits estimates ofroundwood products volume and inventory product volume (growing-
harvested in Montana in 1988 and the associated stock or sawtimber volume).
removals volume. The growing-stock/sawtimber volume in products
Roundwoodproducts came from growing-stocktrees, plus the logging residue equals the growing-stock/
salvable dead trees, and other sources (nontimber sawtimber removals.
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Table 4 Timberand fuelwood production and timber removals by source of material and product, Montana, 1988
Products and Product volume1
additional From growing- From salvable Other Noninventory Growing-stock
removals 1otal stock trees dead trees sources2 productvolume removals
Thousandcubicfeet
OaWIUUo 175 481 14,029 17^ I /J,JUO
Veneer logs3 38,903 38!671 232 39 38,632
Pulpwood4 2,059 2,059 2 2,057
House logs3 2,693 869 1,824 1 868
Other industrial5 3,990 3,728 262 4 3,724
Cedar products3 134 102 31 102
oiai ooc\ qin 16,378 991 99D CQQ
i
Fuelwood6 21,8—75 1,5—48 20,006 7320 —2 1,546
Logging residue8 27,491
iotai 999 AC^Q 36,384 320 9C.9C.9O OAQ ~70CZ
Sawtimber
removals
Thousandboardfeet(Scribnerrule)
Sawlogs 1,000,052 926,019 74,033 45,375 880,644
Veneer logs 205,293 204,071 1,222 9,999 194,072
Piiln\A/nnH 1u,uuu 1 ftfifi 532 10 334
House logs 14,210 4,585 9,625 225 4,360
Other industrial 1,459 1,459 71 1,388
Cedar products 705 539 166 26 513
Total 1,232,585 1,147,539 85,046 56,228 1,091,311
Fuelwood 113,741 8,169 105,572 400 7,769
Logging residue 40,249
Total 1,346,326 1,155,708 190,618 56,628 1,139,329
- Thousandboardfeet(International1A-inch rule)
Sawlogs 1,175,261 1,088,258 87,004 53,325 1,034,933
Veneer logs 241,260 239,824 1,436 11,751 228,073
Pulpwood 12,770 12,770 626 12,144
House logs 16,700 5,388 11,311 264 5,124
Other industrial 1,715 1,715 84 1,631
Cedar products 829 633 195 31 602
Total 1,448,534 1,348,588 99,946 66,081 1,282,507
Fuelwood 133,646 9,598 124,047 470 9,128
Logging residue 46,052
Total 1,582,180 1,358,186 223,993 66,551 1,337,687
1Sawlog, veneer log, pulpwood, house log, cedarproduct, andotherindustrial roundwoodvolumes (McLainandothersinpreparation).
Fuelwoodvolume (McLain 1990).
2Noboard-footvolumeinothersources.
3Volumesreported in thousand boardfeet(Scribnerrule). Cubic-/board-footconversionsarefrom logging utilization study (table2).
"Roundpulpwoodwasreported in mixedunits. These unitswereconvertedtocords. Cordswereconvertedtothousandboardfeet(Scribner
rule) using 3cords/thousand board feet. Conversionsfromthousandboardfeet (Scribnerrule) tothousand boardfeet (International Vi-inch rule)
andthousand cubicfeetused table 2.
5Utilitypoles, posts, and rails. Cubic- and board-foot(Scribnerrule) volumescomputedfrom actualdimensions. Boardfoot(International
Vi-inch rule) volumesderived byconverting Scribnervolumesusingtable2.
6Fuelwoodvolumeswerereported incords. Cordswereconvertedtocubicfeetatthe rateof80cubicfeet/cord (standard ForestServicecon-
version ratein Montana). Table2factorsusedtoconvertcubicvolumetoboard-footvolume.
7RockyMountain maple, elm, and ash.
logging residueisassociatedwiththe harvestofindustrial roundwood products. Logging residueassociatedwithfuelwood harvestisas-
sumedtobezero.
4
Table 5—Removal factors for Montana in 1965, compared to not applying)factors developed from industrial round-
factors computed in 1988 wood operations to fuelwood harvest volumes is
hardly worrisome.
Factor 19651 1988 RLSiIf1f1ACIrCoInIrOoC
Growing-stock Removals Factors, Then and Now
removals (cubic) 1.160 1.121 (-0.039)
Logging residue (cubic) .163 .122 (-.041) Table 5 compares the Montana removals factors
from data collected in 1965 (Wilson and others 1970)
Sawtimber removals
(board feet, International to those from 1988. Current timber harvesting re-
'A-inch rule) 1.056 .985 (-.071) moves 4 percent less growing stock and produces
4 percent less logging residue from growing stock for
Logging residue
the same product volume than in 1965.
(board feet, International
1/4-inch rule) .074 .034 (-.040) Sawtimber volume in logging residue has changed
similarly. The 7 percent decrease in sawtimber
1Wilson andothers 1970.
removals associated with a given board-foot volume
oflogs results in large measure from an increase in
the harvest ofpoletimber.
In table 4 industrial roundwood products are sub-
totaled exclusive offuelwood to simplify comparisons Logging Residue Volume in Pieces
and analysis. 6 Feet and Longer
The estimates ofindustrial roundwoodproducts were
furnished by the primary wood processors who received Table 6 shows the factor to estimate the cubic vol-
logs harvestedinMontana in 1988; separate estimates ume oflogging residue from product trees in pieces
were provided for products from growing-stock trees 6 feet in length and longer to a 4-inch top; the pro-
and salvable dead trees. The growing-stock/sawtimber portion ofproduct trees producing such residue; and
removals component ofthe products, the noninven- the volume ofresidue at least 6 feet long produced
tory product volume component, and the logging resi- in Montana in 1988. The factor, 0.068, means that
due volume were estimated by applying factors from residue volume in pieces 6 feetlong andlonger equals
table 3 to the reported harvest volumes. 6.8 percent ofthe productvolume from growing-stock
The fuelwood estimates, obtained by sampling and trees. Nonproduct tree residue may account for ad-
canvassing commercial fuelwood harvesters, were ditional residue volume in pieces 6 feet and longer.
also obtained separated by growing stock and dead; The proportion oftrees measured that produced
a small volume fell into an additional category, other residue in pieces 6 feet and longer may indicate the
sources, which means nontimber species. Because degree ofutilization. The lower the proportion, the
the logging utilization data were not collected from higher the utilization.
fuelwood harvesting operations, some adjustments
were made to estimate growing-stock/sawtimber re- Diameter Class Distribution ofTrees
movals associated with fuelwood. The appropriate Harvested or Damaged
table 3 factors were usedto estimate the growing-stock/
sawtimber product volume, but residue was esti- Table 7 gives information about the number of
mated to be zero. We assumed that all growing-stock/ growing-stock trees and the growing-stock volume
sawtimber volume in trees cut for fuelwood and trees harvested or destroyed in each diameter class. Such
killed by such logging went into the product. The information can be used when computing diameter
fuelwood product volume from growing-stock trees class cutting rates to project residual inventory,
was very small, less than 1 percent ofthe growing- growth, andyield.
stock removals generatedby the industrial roundwood Information from the 1965 utilization study is pro-
harvest. Consequently, the propriety ofapplying(or vided for comparison.
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Table 6 Volume, proportion of harvest volume (factor), and proportion of producttrees con-
taining logging residue to a4-inch top in pieces 6 feet and longer, Montana, 1988
Residue volume in Factor1 forresidue Proportion of producttrees
pieces 6 feet and longer volume in pieces producing residue volume
(thousand cubicfeet) 6 feet and longer in pieces 6feet and longer
15,022 0.068 0.886
'Applytoproductvolume.
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Table 7 Diameteratbreast height (d.b.h.) classdistribution ofthe num-
berand volume of growing-stocktrees removed from inventory
through harvesting perthousand cubicfeet of net productvol-
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ume, Montana, 1988 with the numberoftrees removed in 1965
provided for comparison. The 1965 volume by d.b.h. class is
unavailable
Numberof Volume ofgrowing-stock
u.D.n. growing-stocktrees trees in cubicfeet
class 9O0 1QyQoQu
I \ —
2 8.93 11.54
4 6.13 6.48 0.08
6 3.03 6.15 18.41
8 2.92 8.08 69.90
10 4.70 8.42 130.12
12 4.34 5.81 126.13
14 4.16 3.37 114.17
16 2.68 1.94 76.26
18 2.26 2.61 144.37
20 1.19 1.85 130.88
22 .60 1.18 107.22
24 .24 .51 49.79
26 .30 .42 55.56
28 .12 .17 26.55
30+ 1.43 .34 72.52
All classes2 43.02 58.87 1,121.98
'Wilson andothers 1970.
2Datamaynotsum tototalsduetotruncatingorrounding.
RELIABILITY OF ESTIMATES n
X*
The computation ofthe standard error ofthe vari- i=l
X =
ous residue and utilization percentages employs the n
formula for the standard error ofa ratio (Cochran
1963, p. 158), which may be stated: SE{%) = 4* x 100 = standarderroroftheratio as a
percentage ofthe ratio
n n n Table 8 gives the achieved standard errors ofthe
l(y -yf l(x.-x? 2 XOc,-x) (y -y) logging residue volume/product volume ratios and
Sr = R2 i-1 t i=l i=l the standard errors as percentages ofthe ratios.
n in -l)y5 (n-l)x2 (n - l)yx
M
where
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y =loggingresiduesmeasured onan operation Table 8^ Achieved standard errors of the logging residue
volume/product volume ratios and the standard
(netvolume)
errors as percentages ofthe ratios
x = timber products measured on anoperation
(netvolume) Standard error
n ofthe ratio
Standard error asa percentage
R = i=l = loggingresidues ratio ofthe ratio ofthe ratio
n (SR) (SE[%])
X*
i=l Cubicfoot 0.0127 10.36
n = total numberofoperations sampled Board foot,
n Scribner rule .0061 17.38
Board foot, International
fm i=L 74-inch rule .0058 16.84
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