United States Department of Agriculture

Forest 

Service

Pacific Northwest 

Research Station

Research Bulletin

PNW-RB-268

November

2016

Logging Utilization in Oregon 

and Washington, 2011–2015

Eric A. Simmons, Todd A. Morgan, Erik C. Berg, Steven W. Hayes, 

and Glenn A. Christensen
In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) 

civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and 

institutions participating in or administering USDA programs are prohibited from discriminating 

based on race, color, national origin, religion, sex, gender identity (including gender 

expression), sexual orientation, disability, age, marital status, family/parental status, income 

derived from a public assistance program, political beliefs, or reprisal or retaliation for prior 

civil rights activity, in any program or activity conducted or funded by USDA (not all bases 

apply to all programs). Remedies and complaint filing deadlines vary by program or incident. 

Persons with disabilities who require alternative means of communication for program 

information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should 

contact the responsible Agency or USDA’s TARGET Center at (202) 720-2600 (voice and 

TTY) or contact USDA through the Federal Relay Service at (800) 877-8339. Additionally, 

program information may be made available in languages other than English. 

To file a program discrimination complaint, complete the USDA Program Discrimination 

Complaint Form, AD-3027, found online at http://www.ascr.usda.gov/complaint_filing_cust.html 

and at any USDA office or write a letter addressed to USDA and provide in the letter all of the 

information requested in the form. To request a copy of the complaint form, call (866) 632-9992. 

Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, 

Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, 

D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov. 

USDA is an equal opportunity provider, employer, and lender.

Authors

Eric A. Simmons is a research associate, Todd A. Morgan is director of forest 

industry research, Erik C. Berg is a research forester, and Steven W. Hayes is a 

research forester, Bureau of Business and Economic Research, University of Montana, 32 Campus Drive, Missoula MT 59812. Glenn A. Christensen is a forester, 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 620 SW Main, Suite 400, Portland, OR 97205.

Produced in cooperation with the Bureau of Business and Economic Research, 

University of Montana, Missoula, Montana.

Cover photos: (upper left) harvester, by Eric Simmons; (upper right) logs, by 

Eric Simmons; (lower left) a crew member measures a tree in Skagit County, Washington, by Chelsea McIver, Oregon Department of Forestry; (lower right) logging 

operation in Pierce County, Washington, by Eric Simmons. 
Abstract 

Simmons, Eric A.; Morgan, Todd A.; Berg, Erik C.; Hayes, Steven W.; 

Christensen; Glenn A. 2016. Logging utilization in Oregon and Washington, 

2011–2015. Resour. Bull. PNW-RB-268. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 24 p. 

A study of commercial timber harvesting activities in Oregon and Washington was 

conducted from 2011 through 2015 to characterize current tree utilization, logging 

operations, and assist with estimating the amount of woody biomass left onsite after 

harvesting. Sample logging sites were selected within major geographic regions 

proportional to regional 5-year timber harvests. A two-stage sampling method was 

used to compute state-level utilization factors. Results of the study indicated that 

in Oregon, for every thousand cubic feet (MCF) delivered to the mill, harvesting 

removed 1,018 cubic feet (CF) of timber volume from growing stock, created 28 CF 

feet of growing-stock logging residue, and 10 CF of non-growing-stock material 

were delivered to the mill. This compared to 1,021 CF of growing-stock removals 

that created 29 CF of growing-stock logging residue and utilized 9 CF of non-growing-stock per 1 MCF of mill-delivered volume in Washington. Analyses showed 

that although utilization varies site to site, tree by tree, and as a result of logging 

practices, the overall effect of these variations on statewide removals factors can be 

minimal. Study results can inform land managers of residues available for bioenergy uses, provide data for woody biomass life cycle analyses, and estimate removals from growing stock. 

Keywords: forest inventory, growing stock removals, logging residue, removals 

factors, timber harvest.

Summary

Logging utilization studies, designed to quantify the amount of logging residue 

generated by commercial timber harvests, have not been conducted in Oregon and 

Washington since the 1980s. These older studies were based on measurements 

taken after product removal, quantifying volumes of logging residue left scattered 

throughout the site. Updated studies were needed in both states to reflect current 

harvesting practices and to directly associate logging residue volumes with harvest 

volumes and Forest Inventory and Analysis (FIA) inventory parameters, such as 

removals from growing-stock. Results indicated that, in Oregon, for every thousand 

cubic feet (MCF) delivered to the mill, 28 CF feet of growing-stock logging residue 

was created; and that in Washington, 29 CF of growing-stock logging residue was 

created per MCF of mill-delivered volume. Thus, removals factors for Oregon and 

Washington were very similar. Although utilization differed by site, by tree, and 

as a result of logging practices, this similarity between states demonstrates that the 

overall effect of these variations on statewide removals factors can be minimal. 

These findings can assist in quantifying the volume of logging residue that may 

be available, within certain economic constraints, for bioenergy, biofuels, or other 

products that could improve overall utilization of the timber resource.
Contents

1 Introduction

3 Recent Oregon and Washington Timber Harvests

7 Methods

9 Data Collection 

10 Data Analysis 

10 Results and Discussion

10 Characteristics of Logging Sites and Operations

12 Characteristics of Felled Trees

16 Statewide Logging Utilization Factors

21 Conclusions

21 Acknowledgments

22 Literature Cited
1

Logging Utilization in Oregon and Washington, 2011–2015

Introduction

For various reasons, Pacific Northwest forest managers desire current information 

on the characteristics and effects of timber harvesting on forest inventory. They 

may wish to know how much woody material remains in the forest after commercial logging operations to understand fuel loads or to predict potential feedstock 

for woody biomass energy. Likewise, the characteristics of harvested trees (e.g., 

dbh,1 total tree height, or species mix) and harvesting methods (e.g., mechanical 

vs. hand felling, merchandising at the stump vs. at the landing, or cable yarding vs. 

ground-based skidding) may be of interest for planning purposes. The information 

developed from logging utilization studies can be useful in quantifying and describing portions of trees left on site after harvesting as logging residue, whether for 

potential biomass supply or as a component of removals from inventory. 

Logging utilization studies identify material removed from forest inventory during commercial timber harvest activities, and they develop logging utilization factors. 

These factors quantify the amount of growing-stock2 volume (fig. 1) removed from 

inventory and distinguish it as either timber products (e.g., sawlogs or pulpwood) 

delivered to mills, or as logging residue, which is left in the forest or at the landing 

(Morgan and Spoelma 2008). These logging utilization factors are used in the calculation of logging residue volumes in the Timber Products Output (TPO) database (http://

srsfia2.fs.fed.us/php/tpo_2009/tpo_rpa_int1.php) maintained by the USDA Forest 

Service’s Forest Inventory and Analysis (FIA) program. The factors can be applied to 

historical or projected levels of timber harvest at various spatial scales to provide estimates of growing-stock removals from forest inventory. Logging utilization studies 

also characterize timber harvest activities and equipment and can provide estimates of 

the distributions of trees and volume harvested by species, size, and logging method. 

When conducted in a consistent manner, these studies can provide a substantial 

amount of information about changes in timber harvesting practices and logging 

residue through time, as well as differences between states or regions. Recent 

logging utilization studies in Idaho (Simmons et al. 2014) and Montana (Morgan et 

al. 2005) have provided updated residue and harvesting information for the Inland 

Northwest. However, studies that link logging residue to TPO and FIA removals 

have not been conducted in Oregon or Washington. Older studies (e.g., Howard 

1 Diameter at breast height (dbh) is the tree’s diameter outside bark, measured at 4.5 feet 

above ground on the uphill side.

2Growing stock is defined as all live trees of commercial species that meet minimum 

merchantability standards or have the potential to meet these merchantability standards. In 

general, these trees have at least one solid 8-foot section; they are reasonably free of form 

defect on the merchantable bole; and 26 percent or more of the tree’s volume is merchantable.

When conducted in 

a consistent manner, 

logging utilization 

studies can provide 

information about 

changes in timber 

harvesting practices 

and logging residue 

through time, as well 

as differences between 

states or regions.
2

RESEARCH BULLETIN PNW-RB-268

1973, 1981a, 1981b) described and quantified slash or logging residue per thousand 

board feet (MBF) harvested; however, these studies did not directly associate the 

residue volume to harvest volumes and FIA inventory parameters (e.g., growingstock vs. non-growing stock3

 sources). This study, and others like it (Bentley and 

Johnson 2004, Morgan and Spoelma 2008, Simmons et al. 2014), make those direct 

connections among timber harvested for products, the associated logging residue, 

and the impacts on growing-stock inventory. 

Sawtimber tree

(≥ 9.0 inches dbh)

Poletimber tree

(5.0–8.9 inches dbh)

Top

4 inches (dob)

7 inches (dob) softwood trees;

 9 inches (dob) hardwood trees

Sawtimber volume 

1-foot stump

Growing stock

portion of tree 

Diameter at breast height

Figure 1—Sections of trees; dbh = diameter at breast height, dob = diameter outside bark.

3 Non-growing-stock sources include wood from below the 1-foot stump height and from 

tops above the 4-inch-diameter outside bark.
3

Logging Utilization in Oregon and Washington, 2011–2015

To update regional timber harvesting and logging residue information, a study 

of logging sites across Oregon and Washington was conducted from 2011 through 

2015. This study was designed to quantify the creation of logging residue from 

commercial timber harvesting at the state level, and characterize harvested trees 

and harvesting activities within each state. The specific objectives were to:

• characterize each state’s timber harvest by tree species and diameter at 

breast height (dbh); 

• characterize each state’s timber harvest operations by felling, yarding, and 

merchandising methods; 

• compute current logging utilization factors for each state to express:

▪ volumes of growing-stock logging residue generated per thousand cubic 

feet (MCF) of mill-delivered volume,

▪ proportions of mill-delivered volume coming from growing-stock vs. 

non-growing-stock portions of harvested trees, and total removals (i.e., 

timber product and logging residue) from growing stock.

Recent Oregon and Washington Timber Harvests

There are nearly 41.5 million acres of nonreserved timberland4 potentially available 

for timber harvest activities in Oregon and Washington (table 1). However, neither 

the timber resource nor harvesting activities are evenly distributed across the states. 

Wood-product markets and forest policy issues have influenced the geographic and 

ownership sources of harvested timber as well as annual harvest volumes.

Recent annual timber harvest volumes in Oregon and Washington combined 

have ranged from mid-decade highs of 8.3 billion board feet (BBF) Scribner in 

2004 to more than a 50-year low of 5 BBF Scribner during 2009 (ODF 2015, 

WDNR 2015a). The ownership mix of the two states’ timber harvest has remained 

fairly stable since 1995, with the majority of the harvest coming from private 

(industrial and nonindustrial) lands (figs. 2a and 2b). With the collapse of U.S. 

housing starts and markets for lumber, there was a marked decline in the volume 

and proportion of harvest from private lands after 2007. Harvests from state-owned 

lands increased, somewhat offsetting declines in private harvests. As federal harvest volumes declined in the 1990s, most dramatically in Oregon (Simmons et al. 

2016), the geographic source of the two states’ timber harvest made a pronounced 

shift to counties west of the Cascade Range, which currently account for 85 to 90 

percent of the annual harvest volume in each state. 

4

 Timberland is defined as unreserved forest land capable of producing 20 cubic feet per 

acre per year of wood from trees classified as a timber species on forest land designated as 

a timber forest type.

As federal harvest 

volumes declined 

in the 1990s, the 

geographic source 

of the two states’ 

timber harvest made 

a pronounced shift to 

counties west of the 

Cascade Range.
4

RESEARCH BULLETIN PNW-RB-268

Table 1—Timberlanda by ownership class

Ownership class Areab Nonreservedc timberland 

Thousands of acres Percent

Oregon:

National forest 11,086 46.9

Undifferentiated privated 9,386 39.7

State 817 3.4

Bureau of Land Management 2,225 9.4

Other public 145 0.6

All owners 23,659 100

Washington:

National forest 5,718 32.1

Undifferentiated privated 9,329 52.3

State 2,302 12.9

Bureau of Land Management 45 0.3

Other public 436 2.4

All owners 17,831 100

a

 Timberland is forest land that is producing or capable of producing more than 20 cubic feet of wood per acre per 

year at culmination of mean annual increment and excludes reserved lands (Helms 1998).

b

 Oregon: 23,659 = 23.7 million ac, Washington: 17,831 = 17.8 millon ac.

c

 Forest land not withdrawn from harvest by statute or administrative regulation. Includes forest lands that are 

not capable of producing more than 20 cubic feet per acre per year of industrial wood in natural stands.

d

 Undifferentiated private includes industrial private, nonindustrial private, tribal, nongovernmental 

organization, and unincorporated local partnership/association/clubs.

Source: USDA FS (2015).
5

Logging Utilization in Oregon and Washington, 2011–2015

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

Timber harvest (million board feet, Scribner log rule)

Year

Other public

State

Federal

Nonindustrial private

 forest and tribal

Industry

Figure 2a—Oregon timber harvest, 1965–2014. Source: ODF (2015).
6

RESEARCH BULLETIN PNW-RB-268

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

Tim

ber harvest (million b

oard feet Scribner)

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

2011

2013

Year

Other

Federal

State

Private

Figure 2b—Washington timber harvest, 1965–2014. Source: WDNR (2015a).
7

Logging Utilization in Oregon and Washington, 2011–2015

Methods

The target populations for this study were active logging sites in Oregon and 

Washington where green (live) trees were being commercially harvested for conversion into wood products, including lumber and veneer/plywood, or for international 

export. Because of the need to measure harvesting impacts on growing stock, only 

green-tree sites were targeted. Salvage sales, with many or most trees dead prior to 

harvest, were not included. Historically, 90 to 95 percent of Oregon and Washington’s annual timber harvest volume had been used for lumber and veneer/plywood 

production (Simmons et al. 2016, WDNR 2015b). Other timber products (e.g., 

pulpwood, posts, and fuelwood) are commonly merchandised with sawlogs. Thus, 

sites were identified where sawlogs and veneer logs were the primary products to be 

harvested, as these would account for the vast majority of annual harvest volume, 

while also capturing some volume for other products. 

The authors sought a sample of felled trees within logging sites (the primary 

sampling unit) that would provide data to estimate logging utilization factors 

expressed as the ratios of means at the Oregon and Washington state levels (Zarnoch et al. 2004). Ideally, the sampling protocol should yield ratios and attendant 

standard errors computed in the same manner as other logging utilization investigations to ensure comparability of results. Most state-level logging utilization 

investigations have reported factors and standard errors using design-based methods without selecting sample sites at random from a list of all active logging sites, 

i.e., the sampling frame (McClain 1996, Morgan and Spoelma 2008, Simmons et 

al. 2014). As Morgan and Spoelma (2008) described, it is not possible to know in 

advance the full population of logging sites in a state for a given year and simply 

draw a sample of those sites to measure. But without a sampling frame to draw 

samples at random, design-based sampling could bias parameter estimates and compromise any ability to make population inferences (Lohr 2009). Berg et al. (2015) 

analyzed the potential bias in design-based sampling without the use of a sampling 

frame and found that the computed design-based residue ratio exhibited less than 

0.5-percent bias. In the current study, as in other investigations, the authors could 

not obtain a list of all active sites. So, sample sites were not selected at random, and 

ratios of means and standard errors were computed using design-based methods. 

A two-stage sampling scheme was then used to select logging sites and trees 

within sites for measurement (Levy and Lemeshow 1999). The number of logging 

sites in an area (e.g., county or multi-county region) was assumed to be proportional 

to harvest volume. Sample sites were thus selected proportional to 5-year timber 

harvest volumes. Logging sites with active harvesting of green trees for commercial 

products served as the stage-1 sampling units. Annual timber-harvest summaries 
8

RESEARCH BULLETIN PNW-RB-268

(BBER 2016) provided the geographic location (i.e., county and state) and ownerships of potential sample logging sites (fig. 3). Timberland owners and sawmills in 

the two states were contacted periodically throughout the study to identify when 

and where logging activities would be occurring and to request access to logging 

sites to conduct measurements.

Figure 3—Logging utilization sample sites by region.
9

Logging Utilization in Oregon and Washington, 2011–2015

The stage-2 sampling units consisted of felled trees at each selected logging 

site. To qualify as a potential measurement tree, it had to be growing stock (live 

prior to harvest, with a dbh ≥ 5 inches, and meeting minimum merchantability 

standards), and the entire stem, including the stump and top, had to be measureable 

(Morgan and Spoelma 2008, Woudenberg et al. 2010). 

Sample sizes for stage 1 and 2 sample units were guided by standard errors 

achieved in previous utilization studies. Zarnoch et al. (2004) found that standard 

errors for utilization ratios dropped substantially by increasing the number of measured logging sites from 10 to 20. Previous logging utilization studies in Montana, 

Idaho, and California garnered low standard errors by measuring 25 to 35 trees 

on each of 30 to 35 logging sites (Morgan et al. 2005, Morgan and Spoelma 2008, 

Simmons et al. 2014). Further, logging utilization studies conducted by the USDA 

Forest Service Southern Research Station (Bentley and Johnson 2004, Zarnoch 

et al. 2004) suggested that a sample of 30 to 50 logging sites with 20 to 35 felled 

trees measured at each logging site would be sufficient to determine state-level 

utilization factors. 

Data Collection 

Logging contractors or foresters at each selected site were contacted 3 to 5 

days prior to site visits to confirm access and outline protocols to ensure field 

crew safety. At each logging site, they provided information on tree species, 

products merchandised, and preferred and acceptable log lengths delivered to 

receiving mill(s). Field crews recorded this information along with the date, 

county, land ownership class, felling method, yarding/skidding method, log 

merchandising location and method, logging contractor name, equipment in 

use, and receiving mill(s).

Field crews selected felled trees meeting the specified requirements at random. 

Individual trees or piles accumulated for skidding were scattered throughout the 

logging site, depending on the operation and equipment used. A unique identification number was assigned to each measurement tree, and species, dbh, and primary 

product (e.g., sawlog, veneer log, etc.) information was recorded. Diameter and 

section length measurements were taken at the cut stump, at 1 foot above ground 

level (uphill side of the tree), at dbh, the end of the first 16-foot log, at the 7.0-inch 

diameter outside bark (dob), at the 4.0-inch dob point (end of growing stock), at 

the end-of-utilization, and at the tip of the tree. Each tree had diameter (in 0.1-inch 

increments) and section length (in 0.1-foot increments) measurements recorded 

with a maximum section length of 16 feet. Thus, for each bole section, lower and 

Diameter and section 

length measurements 

were taken at the cut 

stump, at 1 foot above 

ground level, at dbh, 

the end of the first 16-

foot log, at the 7.0-inch 

diameter outside bark 

(dob), at the 4.0-inch 

dob point, at the endof-utilization, and at 

the tip of the tree.
10

RESEARCH BULLETIN PNW-RB-268

upper dob and length were recorded. The percent cubic cull for each section was 

also recorded and each bole section was identified as utilized (delivered to the mill) 

or unutilized (logging residue). When evident, the timber product type for each 

utilized section was also recorded. 

A minimum of 20 felled live trees were measured at each of 64 logging sites in 

both states (Oregon 34, Washington 30) from 2011 through 2015. These 64 active 

logging sites were spread across Oregon and Washington, and a total of 1,561 felled 

trees were measured.

Data Analysis 

Following the methods of Morgan and Spoelma (2008) and Simmons et al. (2014), 

cubic volumes for more than 16,700 individual tree sections were calculated using 

Smalian’s formula (Avery and Burkhart 1994). Section volumes were summed 

for each tree by category (e.g., utilized vs. unutilized stump, bole, and upper stem 

sections of the trees), and utilization factors were calculated for each tree and site. 

Logging residue factors, standard errors, and 95-percent confidence intervals (CIs) 

were computed at the state level for Oregon and Washington based on the two-stage 

sampling design using the ratios of means estimator (Zarnoch et al. 2004) obtained 

from SAS PROC SURVEYMEANS (SAS 2013).5 Characteristics of the felled trees, 

harvest operations, and utilization factors were then summarized and compared 

with historical Oregon and Washington logging utilization studies and with recent 

studies from other Western states.

Results and Discussion

Characteristics of Logging Sites and Operations

Because the majority of commercial logging in both states occurs in the regions 

west of the Cascades, most of the sample sites were located in these regions (table 

2). Limited availability of logging sites in the Central region of Oregon (fig. 3) and 

the Puget Sound region of Washington resulted in fewer sites being measured relative to average harvest volumes in those regions. Likewise, the proportion of federal 

(Forest Service and Bureau of Land Management) sites in Oregon and nonindustrial 

private forest sites in Washington were somewhat lower than average harvest 

proportions for those ownerships (table 3).

5

 The use of trade or firm names in this publication is for reader information and does not 

imply endorsement by the U.S. Department of Agriculture of any product or service.
11

Logging Utilization in Oregon and Washington, 2011–2015

Table 2—Percentage of 5-year-average harvest and sample sites by region

Region Harvest Sample

- - - - - - - Percent - - - - - - -

Oregon:

Northwest 47 50

Southwest 40 41

Central 7 3

Blue Mountain 6 6

Total 100 100

Washington:

Southwest 38 40

Olympic Peninsula 28 30

Puget Sound 19 13

Central 6 7

Inland Empire 9 10

Total 100 100

Table 3—Percentage of 5-year-average harvest and sample sites by ownership

Ownership Number 

of sites

Percentage 

of sites

Percentage 

of harvest

Oregon:

Industry 24 70 65

Nonindustrial private forest 2 6 9

State and other public 6 18 10

Federal 2 6 16

Total 34 100 100

Washington:

Industry 11 36 27

Nonindustrial private forest 11 37 48

State and other public 5 17 20

Federal 3 10 5

Total 30 100 100

Note: Washington nonindustrial private forest (NIPF) includes large private timber investment management 

organizations (TIMOs).
12

RESEARCH BULLETIN PNW-RB-268

Harvesting methods included hand or mechanical felling and merchandising, as well as sites with a mix of the two (table 4). Mechanical felling methods 

included the use of equipment with accumulating heads such as a “hot saw” 

or feller-buncher. Hand felling and merchandising was done with chainsaws. 

Yarding operations were accomplished with cable or ground-based systems 

depending on topography or prescription. Cable systems were typically towers 

with motorized carriages. Ground-based skidding included the use of shovels,6

rubber-tired skidders, and rarely with bulldozers equipped with either a grapple 

or a winch with chokers. Trees were skidded both tree- and log-length. Mechanical merchandising methods included the use of stroke (slide-boom) delimbers and 

dangle-head processors.

In Oregon, hand felling occurred on 53 percent of the sites, whereas in 

Washington 53 percent of sites were felled mechanically. Cable yarding was used 

on 53 percent of the sites in Oregon and 27 percent of the sites in Washington. 

This was primarily due to a greater number of sites with steep slopes in Oregon. 

In both states, tree-length skidding predominated. Ground-based skidding with 

shovels (i.e., shovel logging) was common, especially on industrial private lands, 

in Oregon and Washington. The processing or merchandising of trees at landings 

with mechanical systems was employed on all but two of the 64 sites in this study. 

Complete merchandising with chainsaws was observed on just one site in each 

state. However, some of the largest trees were bucked once—at the end of the first 

(butt) log—on several cable sites.

Characteristics of Felled Trees

The trees analyzed in Oregon ranged from 5.0 to 31.3 inches dbh; Washington trees 

ranged from 5.0 to 37.2 inches dbh (table 5). Half of the trees measured in Oregon 

were ≤ 14.0 inches dbh, but they accounted for about 18 percent of the utilized 

volume and 23 percent of growing-stock logging residue. Roughly one-half of the 

utilized volume and total logging residue in Oregon came from trees < 18.0 inches 

dbh. As in Oregon, 50 percent of the harvested trees in Washington were ≤ 14.0 

inches dbh. These trees accounted for about 16 percent of the mill-delivered volume 

and just 13 percent of growing-stock logging residue volume. About one-half of 

Washington’s utilized volume was produced by trees < 18.0 inches dbh, the same as 

in Oregon. However, more logging residue came from larger diameter trees in Washington, particularly in the 24 to 34 inch dbh classes. This finding is different than 

6 Shovel: typically an excavator with a boom and grapple used to move felled trees from 

within a unit to a landing for processing or to load log trucks. When this system is used, the 

operation is referred to as “shovel logging.”

In Oregon, hand felling 

occurred on 53 percent 

of the sites, whereas in 

Washington 53 percent 

of sites were felled 

mechanically. Cable 

yarding was used 

on 53 percent of the 

sites in Oregon and 27 

percent of the sites in 

Washington.
13

Logging Utilization in Oregon and Washington, 2011–2015

Table 4—Number of sampled sites by logging methods and ownership class 

Felling Yarding Skidding

Merchandizing 

location

Merchandizing

method

Ownership Handa Mechanical Mixed Ground Cable Tree length Log length In unit At landing Handa Mechanical

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Number of sites - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Oregon (34 sites):

Federal 1 1 0 1 1 2 0 0 2 1 1State 6 0 0 0 6 6 0 0 6 0 6Nonindustrial private forest 1 0 1 2 0 2 0 0 2 0 2Industrial private 10 11 3 13 11 24 0 0 24 0 24

Total 18 12 4 16 18 34 0 0 34 1 33

Washington (30 sites):

Federal 2 1 0 1 2 1 2 1 2 0 3State 2 2 1 3 2 5 0 0 5 1 4Nonindustrial private forest 1 6 4 8 3 11 0 0 11 0 11Industrial private 0 7 4 10 1 11 0 0 11 0 11

Total 5 16 9 22 8 28 2 1 29 1 29

a With chainsaws.
14

RESEARCH BULLETIN PNW-RB-268 Table 5—Distribution of trees, mill-delivered volume, and growing-stock logging-residue volume in cubic feet, by dbh class (continued)

dbh class 

(inches)

Number 

of trees

Percentage of 

sample trees

Cumulative 

percentage

 Percentage of mill 

delivered volume

Cumulative 

percentage

Percentage of growingstock logging residue Cumulative percentage

Cubic feet Cubic feet

Oregon (835 trees):

6 17 2.0 2.0 0.2 0.2 0.1 0.18 84 10.1 12.1 1.9 2.1 4.4 4.5

10 125 15.0 27.1 5.8 7.9 8.3 12.8

12 139 16.6 43.7 9.7 17.6 10.5 23.3

14 138 16.5 60.2 13.5 31.1 13.1 36.4

16 107 12.8 73.1 14.5 45.6 9.5 46.0

18 82 9.8 82.9 14.1 59.7 12.3 58.3

20 59 7.1 89.9 12.8 72.6 10.7 69.0

22 30 3.6 93.5 7.6 80.2 7.5 76.5

24 20 2.4 95.9 6.3 86.5 4.2 80.7

26 14 1.7 97.6 5.0 91.5 8.9 89.6

28 15 1.8 99.4 6.1 97.5 5.9 95.5

30 4 0.5 99.9 1.8 99.4 2.7 98.2

32 1 0.1 100 0.6 100 1.8 100
15

Logging Utilization in Oregon and Washington, 2011–2015

Table 5—Distribution of trees, mill-delivered volume, and growing-stock logging-residue volume in cubic feet, by dbh class (continued)

dbh class 

(inches)

Number 

of trees

Percentage of 

sample trees

Cumulative 

percentage

 Percentage of mill 

delivered volume

Cumulative 

percentage

Percentage of growingstock logging residue Cumulative percentage

Washington (726 trees):

6 11 1.5 1.5 0.2 0.2 0.4 0.48 65 9.0 10.5 1.9 2.1 1.5 1.9

10 91 12.5 23.0 3.9 5.9 3.6 5.5

12 137 18.9 41.9 9.7 15.6 7.7 13.2

14 123 16.9 58.8 12.2 27.8 7.8 21.0

16 112 15.4 74.2 15.5 43.3 11.0 32.0

18 59 8.1 82.4 10.5 53.8 6.9 38.9

20 46 6.3 88.7 10.4 64.2 13.7 52.6

22 16 2.2 90.9 4.5 68.7 3.3 55.9

24 15 2.1 93.0 5.5 74.3 2.7 58.6

26 15 2.1 95.0 5.6 79.8 11.4 70.0

28 12 1.7 96.7 5.4 85.3 6.0 75.9

30 8 1.1 97.8 4.1 89.4 8.9 84.8

32 7 1.0 98.8 4.5 93.9 6.6 91.5

34 6 0.8 99.6 3.9 97.8 6.6 98.0

36 2 0.3 99.9 1.4 99.3 1.1 99.1

38 1 0.1 100 0.7 100 0.9 100

dbh = diameter at breast height.Note: Percentages may not sum to 100 because of rounding.
16

RESEARCH BULLETIN PNW-RB-268

in Oregon and is inconsistent with studies in other Western states, where smaller 

trees tended to produce proportionally more residue per cubic foot of mill-delivered 

volume than larger trees (Morgan and Spoelma 2008, Simmons et al. 2014). 

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco); western hemlock (Tsuga 

heterophylla (Raf.) Sarg.); hardwoods, primarily red alder (Alnus rubra Bong.); 

and true firs (Abies spp.) were the four most sampled and harvested tree species in 

Oregon (table 6). These species accounted for 96 percent of the mill-delivered volume from Oregon sites in this study and 92 percent of the 2013 harvest as reported 

by Simmons et al. (2016). In Washington, these species accounted for 93 percent 

of the mill-delivered volume in this study and 92 percent of 2014 log consumption 

as reported by the Washington Department of Natural Resources (WDNR 2015b). 

The mill-delivered volume of pines (Pinus spp.) measured in the sample of logging 

sites from both states was somewhat lower than reported pine volumes from other 

sources. This was likely a result of the small number of sites located east of the 

Cascades in both Oregon and Washington, where pine species are more commonly 

harvested (Simmons et al. 2016, WDNR 2015b). Hardwoods and true firs exhibited 

higher residue ratios (growing-stock logging residue as a percentage of mill-delivered volume) than other species groups in both Oregon and Washington.

Statewide Logging Utilization Factors

Logging utilization removals factors are statewide ratios of removals volumes versus 

mill-delivered volumes (Morgan and Spoelma 2008, Simmons et al. 2014). Removals 

factors calculated in this study indicated that commercial timber harvesting in Oregon 

removed 1,018 CF of growing-stock volume for each 1,000 CF delivered to the mill: 

990 CF of growing stock was utilized, plus 28 CF of growing stock was left in the 

forest or at the landing as logging residue (table 7). In addition, 10 CF of non-growingstock material from stumps cut below 1-foot in height and tops (utilized beyond the 

4-inch dob) that went to the mill. Washington removals factors were very similar to 

those found in Oregon. For each 1,000 CF delivered to the mill, 1,021 CF of growing 

stock was removed, with 991 CF utilized and 29 CF left on site as logging residue. 

And, an additional 9 CF of non-growing-stock material was delivered to the mill.

Most of the growing-stock logging residue came from portions of the bole that 

were broken during felling and stumps cut higher than 1.0 foot above ground level. 

Berg (2014) found that breakage accounted for more than 90 percent of individual 

tree growing-stock residue in a four-state logging residue investigation. Relatively 

little logging residue came from stem sections near the end of growing stock (i.e., 

the 4-inch dob). There is less volume in the smaller diameter (upper) portions of the 

bole, compared to stump sections. However, Berg et al. (2016) found that although 

Most of the growingstock logging residue 

volume came from 

portions of the bole 

that were broken during 

felling and stumps cut 

higher than 1.0 foot 

above ground level.
17

Logging Utilization in Oregon and Washington, 2011–2015

changes in small-end utilized diameters (e.g., 4.0 inches dob versus 6.0 inches dob) 

yielded small differences in residue volume, residue ratios increased exponentially 

as small-end-utilized diameters increased.

The amount of growing-stock residue generated per unit of mill-delivered 

volume (i.e., the growing-stock residue factor) differed between Oregon and 

Washington in some diameter classes (fig. 4). In Washington, the residue factor 

for trees in the 6-inch diameter class was over six times higher than in Oregon. 

This difference resulted from more pulpwood utilization at some Oregon sites, 

and may have been related to different minimum log-length specifications for pulp 

products in Oregon versus Washington. Although the low residue factor for 6-inch 

dbh trees in Oregon was contrary to findings in other states (e.g., Simmons et al. 

2014), it was consistent with findings by Berg et al. (2016) that harvesting pulpwood improved overall utilization and reduced the growing-stock residue factor. 

The growing-stock residue factor for trees in the 24- to 30-inch dbh classes 

was 33 percent higher in Washington than in Oregon. Much of this difference was 

attributable to three sites in Washington where larger trees had been felled across 

Table 6—Proportion of felled trees, harvest, delivered volume, total logging residue, and residue per cubic 

foot delivered volume by species

Species

Number 

of sample 

trees

Percentage 

of harvests in 

Oregon (2013) and 

Washington (2014)

 Percentage of 

mill-delivered 

volume

Percentage of 

total logging 

residue

Residue as a 

percentage of milldelivered volume

Oregon:

Douglas-fir 586 69.5 73.3 57.2 2.2

Western hemlock 146 11.2 17.2 22.6 3.7

Hardwoods 40 3.5 2.4 10.8 12.7

True firs 33 8.0 3.2 5.8 5.1

Other softwoods 18 3.0 2.4 2.1 2.4

Pines 12 4.8 1.6 1.4 2.5

All species 835 100 100 100 2.8

Washington:

Douglas-fir 382 60.3 61.8 52.4 2.5

Western hemlock 199 24.2 24.5 26.8 3.2

Other softwoods 62 4.1 5.0 5.3 3.2

True firs 40 3.8 4.3 7.0 4.7

Hardwoods 33 3.6 2.7 7.3 8.0

Pines 10 4.0 1.8 1.2 2.1

All species 726 100 100 100 2.9

The growing-stock 

residue factor for 

trees in the 24- to 30-

inch dbh classes was 

higher in Washington 

because three sites 

had larger trees felled 

across bunch piles, 

creating considerable 

damage to—and 

residue from—the 

larger trees. 
18

RESEARCH BULLETIN PNW-RB-268

Table 7—Logging utilization removals factorsRemovals factors 

Lower bound 

(95% CI)

Estimate 

(ratio of means)

Upper bound 

(95% CI)

Standard 

error

Cubic feet per milldelivered MCF

Oregon:

Non-growing-stock product delivered to mills (utilized non-growing stock ÷ total utilized)

0.0051 0.0102 0.0153 0.0025 10

Growing-stock product delivered to mills (utilized growing stock ÷ total utilized)

0.9847 0.9898 0.9949 0.0025 990

Growing-stock logging residue (unutilized growing stock ÷ total utilized)

0.0209 0.0278 0.0348 0.0034 28

Removals from growing stock ((utilized + unutilized growing stock) ÷ total utilized)

1.0096 1.0176 1.0257 0.0040 1,018

Washington:

Non-growing stock-product delivered to mills (utilized non-growing-stock ÷ total utilized)

0.0056 0.0090 0.0123 0.0016 9

Growing-stock product delivered to mills (utilized growing stock ÷ total utilized)

0.9877 0.9910 0.9944 0.0016 991

Growing-stock logging residue (unutilized growing stock ÷ total utilized)

0.0206 0.0294 0.0382 0.0043 29

Removals from growing stock ((utilized + unutilized growing stock) ÷ total utilized)

1.0088 1.0204 1.0320 0.0057 1,021

CI = confidence interval; MCF = thousand cubic feet.
19

Logging Utilization in Oregon and Washington, 2011–2015

20

18

16

14

12

10

8

6

4

2

0

6 8 10 12 14 16 18 20 22 24 26 28 30 32

Percent

Diameter at breast height (dbh) class

Diameter at breast height (dbh) class

Oregon

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

Washington

20

18

16

14

12

10

8

6

4

2

0

Percent

Mill delivered volume

Harvested trees

Residue factor

Mill delivered volume

Harvested trees

Residue factor

Figure 4—Distribution of mill delivered volume, harvested trees, and residue per cubic foot of milldelivered volume by tree diameter at breast height (dbh).
20

RESEARCH BULLETIN PNW-RB-268

bunch piles of smaller trees, creating considerable damage to—and residue from—

the larger trees as well as the trees in the piles. Compared to trees of the same 

diameter at other sites in Washington, the growing-stock logging residue factor 

was almost twice as high for these three sites. These findings suggest that, although 

statewide residue factors may have been similar, differences in product utilization 

and logging practices clearly affected logging residue quantities at individual sites. 

Results of this study can also be used to characterize utilization of the entire 

bole of the harvested tree. In Oregon, 3.5 percent of the entire harvested bole 

volume (i.e., portions of the tree from the cut stump to the tip of the tree, excluding 

branches) remained in the woods as logging residue, and 96.5 was delivered to the 

mill (fig. 5). Washington’s harvested tree bole utilization was nearly identical. This 

information can benefit forest managers who do not use the FIA distinctions of 

growing-stock and non-growing-stock tree components.

Harvested tree bole* Oregon (portions of tree from cut stump to tip of main stem)

1.0% 95.5% 2.7% 0.7%

Harvested tree bole* Washington (portions of tree from cut stump to tip of main stem)

0.9% 95.6% 2.8% 0.7%

Non-growing-stock mill delivered

Growing-stock logging residue

Growing-stock mill delivered

Non-growing-stock bole residue

* Excludes branches 

 and forked tops.

Figure 5—Harvested tree bole utilization.
21

Logging Utilization in Oregon and Washington, 2011–2015

Conclusions

Logging utilization studies can help land managers understand the impacts of commercial timber harvesting on growing-stock inventories, woody residue volumes, 

and carbon dynamics. Variables including logging method, species, tree size (i.e., 

dbh), defect, and the presence/absence of a pulp market can have profound impacts 

on the production of logging residue (Berg et al. 2016, Simmons et al. 2014). 

The sampling design used in this study appears to have captured the range in 

variability of recent Oregon and Washington logging sites and harvested trees. Site 

locations, as reflected in geographic distribution and species mix in the sample, 

closely approximated timber harvest information reported in both states (Simmons 

et al. 2016, WDNR 2015a). Results also suggest that the sampling scheme did well 

at capturing information on the more frequently harvested species, but perhaps not 

as well with the less frequently harvested species. 

This study produced removals factors for Oregon and Washington that enabled 

calculation of growing-stock logging residue quantities based on current, local 

harvesting practices. Removals factors for Oregon and Washington were nearly 

identical, even though utilization differed site to site, tree by tree, and as a result 

of logging practices, demonstrating that the overall effect of these variations on 

statewide removals factors, when all the data are combined, can be minimal. These 

residue factors can aid land managers in estimating the quantities of logging residue 

removed from growing stock and potentially available for bioenergy uses, while 

also providing information for woody biomass life cycle analyses.

Acknowledgments

The authors gratefully acknowledge the financial support of the Northwest 

Advanced Renewables Alliance (NARA), supported by the Agriculture and Food 

Research Initiative Competitive Grant no. 2011-68005-30416, USDA National 

Institute of Food and Agriculture; and the USDA Forest Service, Pacific Northwest 

Research Station, Forest Inventory and Analysis program, Portland, Oregon. Other 

cooperators included the Oregon Department of Forestry, Washington Department 

of Natural Resources, and numerous industrial private landowners, foresters, and 

loggers without whose assistance this analysis could not have been accomplished.

Removals factors 

for Oregon and 

Washington were 

nearly identical, even 

though utilization 

differed site to 

site, tree by tree, 

and as a result of 

logging practices, 

demonstrating that the 

overall effect of these 

variations on statewide 

removals factors, 

when all the data are 

combined, can be 

minimal. 
22

RESEARCH BULLETIN PNW-RB-268

Literature Cited

Avery, T.E.; Burkhart, H.E. 1994. Forest measurements. 4th ed. New York: 

McGraw-Hill. 408 p. 

Bentley, J.W.; Johnson, T.G. 2004. Eastern Texas harvest and utilization study, 

2003. Resour. Bull. SRS-97. Asheville, NC: U.S. Department of Agriculture, 

Forest Service, Southern Research Station. 28 p.

Berg, E.C.; Morgan, T.A.; Simmons, E.A.; Zarnoch, S.J. 2015. Logging 

utilization research in the Pacific Northwest: residue prediction and unique 

research challenges. In: Stanton, S.M.; Christensen, G.A., comps. 2015. Pushing 

boundaries: new directions in inventory techniques & applications. Forest 

Inventory and Analysis (FIA) symposium 2015. Gen. Tech. Rep. PNW-GTR-931. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest 

Research Station. 384 p.

Berg, E.C. 2014. Causes of felled-tree residue creation. Unpublished report. 

Analyses completed for the Northwest Advanced Renewables Alliance. On 

file with: University of Montana, Bureau of Business and Economic Research, 

Gallagher Business Building, 32 Campus Drive #6840, Missoula, MT 59812-

6840.

Berg, E.C.; Morgan, T.A.; Simmons, E.A.; Zarnoch, S.J.; Scudder, M. 2016.

Predicting logging residue volumes in the Pacific Northwest. Forest Science. 

http://dx.doi.org/10.5849/forsci15176. (21 July 2016).

Bureau of Business and Economic Research [BBER]. 2016. Harvest and 

industry: harvest by county Web tool. Missoula, MT: University of Montana. 

http://www.bber.umt.edu/FIR/H_Harvest.asp. (18 July 2016).

Helms, J.A. 1998. The dictionary of forestry. 1st ed. Bethesda, MD: Society of 

American Foresters. 210 p. 

Howard, J.O. 1973. Logging residue in Washington, Oregon, and California: 

volume and characteristics. Resour. Bull. PNW-44. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Forest and Range 

Experiment Station. 26 p.

Howard, J.O. 1981a. Ratios for estimating logging residue in the Pacific 

Northwest. Res. Pap. PNW-288. Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Forest and Range Experiment Station. 26 p.
23

Logging Utilization in Oregon and Washington, 2011–2015

Howard, J.O. 1981b. Logging residue in the Pacific Northwest: Characteristics 

affecting utilization. Res. Pap. PNW-289. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment 

Station. 41 p.

Levy, P.S.; Lemeshow, S. 1999. Sampling of populations: methods and 

applications. 3rd ed. New York: Wiley Inc. 525 p.

Lohr, S.L. 2009. Sampling: design and analysis. 2nd ed. Boston, MA: Brooks/Cole, 

Cengage Learning. 596 p.

McLain, W.H. 1996. Logging utilization—Idaho, 1990. Resour. Bull. INT-RB-86. 

Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain 

Research Station. 16 p.

Miles, P.D. 2016. Forest Inventory EVALIDator web-application Version 1.6.0.03. 

St. Paul, MN: U.S. Department of Agriculture, Forest Service, Northern 

Research Station. http://apps.fs.fed.us/Evalidator/evalidator.jsp. (27 July 2016).

Morgan, T.A.; Spoelma, T.P. 2008. California logging utilization: 2004. Western 

Journal of Applied Forestry. 23(1): 12–18.

Morgan, T.A.; Spoelma, T.P.; Keegan, C.E., III; Chase, A.L.; Thompson, M.T. 

2005. Montana logging utilization, 2002. Res. Pap. RMRS-RP-52. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station. 12 p.

Oregon Department of Forestry [ODF]. 2015. Timber harvest data 1942–2015. 

https://data.oregon.gov/Natural-Resources/Timber-Harvest-Data-1942-2015/

xgf5-eqeq. (27 July 2016.

SAS. 2013. SAS version 9.4. Cary, NC: SAS Institute Inc.

Simmons, E.A.; Berg, E.C.; Morgan, T.A.; Zarnoch, S.J.; Hayes, S.W.; 

Thompson, M.T. 2014. Logging utilization in Idaho: current and past trends. 

Gen. Tech. Rep. RMRS-GTR-318. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 15 p. 

Simmons, E.A.; Scudder, M.G.; Morgan, T.A.; Berg, E.C.; Christensen, G.A. 

2016. Oregon’s forest products industry and timber harvest, 2013 with trends 

through 2014. Gen. Tech. Rep. PNW-GTR-942. Portland, OR: U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Research Station. 58 p.
24

RESEARCH BULLETIN PNW-RB-268

U.S. Department of Agriculture, Forest Service [USDA FS]. 2015. PNWFIADB: Pacific Northwest annual forest inventory database (AK, CA, OR, WA). 

[Database]. http://www.fs.fed.us/pnw/rma/fia-topics/inventory-data/index.php. 

(27 July 2016).

Washington Department of Natural Resources [WDNR]. 2015a. Washington 

state timber harvest reports. http://www.dnr.wa.gov/TimberHarvestReports. 

(18 July 2016).

Washington Department of Natural Resources [WDNR]. 2015b. Washington 

state mill survey 2014. Series Report #23. Olympia WA: 84 p. http://www.dnr.

wa.gov/about/fiscal-reports/washington-state-mill-surveys. (18 July 2016).

Witt, C.; Shaw, J.D.; Thompson, M.T.; Goeking, S.A.; Menlove, J.; Amacher, 

M.C.; Morgan, T.A.; Werstak, C.. 2012. Idaho’s forest resources, 2004–2009. 

Resour. Bull. RMRS-RB-14. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station. 134 p.

Woudenberg, S.W.; Conkling, B.L.; O’Connell, B.M.; LaPoint, E.B.; Turner, 

J.A.; Waddell, K.L. 2010. The Forest Inventory and Analysis database: database 

description and users manual version 4.0 for Phase 2. Gen. Tech. Rep. RMRSGTR- 245. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 336 p.

Zarnoch, S.J.; Bentley, J.W.; Johnson, T.G. 2004. Determining sample size for 

tree utilization surveys. Res. Pap. SRS-34. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southern Research Station. 11 p. 
Pacific Northwest Research Station

Website http://www.fs.fed.us/pnw/

Telephone (503) 808–2592

Publication requests (503) 808–2138

FAX (503) 808–2130

E-mail pnw_pnwpubs@fs.fed.us

Mailing address Publications Distribution

Pacific Northwest Research Station

P.O. Box 3890

Portland, OR 97208–3890
U.S. Department of Agriculture

Pacific Northwest Research Station

1220 SW 3rd Ave., Suite 1400

P.O. Box 3890

Portland, OR 97208–3890

Official Business

Penalty for Private Use, $300