United States Department of Agriculture

Forest Rocky Mountain Resource Bulletin

Service Research Station RMRS-RB-28 October 2018

Wyoming’s Forest Resources, 2011–2015

R. Justin DeRose, John D. Shaw, Sara A. Goeking, Kate Marcille, 

Chelsea P. McIver, Jim Menlove, Todd A. Morgan, and Chris Witt
All Rocky Mountain Research Station publications are produced by U.S. Forest Service employees and are in the 

public domain and available at no cost. Even though U.S. Forest Service publications are not copyrighted, they are 

formatted according to U.S. Department of Agriculture standards and research findings and formatting cannot be 

altered in reprints. Altering content or formatting, including the cover and title page, is strictly prohibited.

Cover photo: Salt River Range, Wyoming (photo: R.J. DeRose).

DeRose, R. Justin; Shaw, John D.; Goeking, Sara A.; Marcille, Kate; McIver, Chelsea P.; Menlove, Jim; Morgan, 

Todd A.; Witt, Chris. 2018. Wyoming’s forest resources, 2011–2015. Resour. Bull. RMRS-RB-28. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 132 p.

Abstract

This report summarizes the most recent inventory of Wyoming’s forests based on field data collected between 

2011 and 2015. The report includes descriptive highlights and tables of area, numbers of trees, biomass, 

carbon, volume, growth, mortality, and removals. Most sections and tables are organized by forest type or 

forest-type group, species group, diameter class, or owner group. The report also describes the inventory 

design, inventory terminology, and data reliability. Results show that Wyoming’s forest land covers 10.5 million acres. Fifty-five percent (5.8 million acres) of this forest land is administered by the USDA Forest Service, 

and another 26 percent (2.8 million acres) is administered by other Federal agencies. There are approximately 

1.5 million acres (14 percent) of privately owned forest land in Wyoming. Wyoming’s most abundant forest-type 

group is Fir/spruce/mountain hemlock, which covers more than 2.9 million acres, but is followed closely by 

the Lodgepole pine forest-type group, which covers more than 2.5 million acres. Lodgepole pine is the most 

abundant species by number of trees but is second to the Fir/spruce/mountain hemlock forest-type group in 

volume (and biomass), 4.2 and 6.2 million cubic feet, respectively. In total, Wyoming’s forests contain more than 

14.6 million cubic feet of net volume in trees 5.0 inches in diameter and larger. Gross growth of all live trees 

5.0 inches in diameter and larger averaged 270.4 million cubic feet per year. Average annual mortality amounts 

to 578.3 million cubic feet per year. Therefore, average annual net growth was -361.2 million cubic feet per year. 

The primary mortality causing disturbance agents were, in descending order, insects, fire, and disease, which 

affected 1,415.3, 446.3, and 382.8 thousand acres, respectively.

Keywords: biomass, estimates, forest inventory, field data, growth, mortality, volume, Wyoming
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.

Authors

R. Justin DeRose is a Research Ecologist with the Interior West Forest Inventory and Analysis Program at the 

Rocky Mountain Research Station in Ogden, Utah. He holds B.S. and M.S. degrees in Forestry from Utah State 

University and the University of Maine, and a Ph.D. in Forest Ecology from Utah State University.

John D. Shaw is a Biological Scientist and Analysis Team Leader with the Interior West Forest Inventory and 

Analysis Program at the Rocky Mountain Research Station in Ogden, Utah. He holds B.S. and M.S. degrees in 

Natural Resources Management from the University of Alaska Fairbanks, and a Ph.D. in Forest Ecology from 

Utah State University.

Sara A. Goeking is a Biological Scientist and a member of the Analysis Team with the Interior West Forest 

Inventory and Analysis Program at the Rocky Mountain Research Station in Ogden, Utah. She holds a B.S. 

degree in Environmental Studies and an M.S. degree in Forest Ecology, both from Utah State University.

Kate Marcille is a Research Associate with the Forest Industry Research Program at the University of Montana’s 

Bureau of Business and Economic Research in Missoula, Montana. Kate holds a B.A. degree in Economics and 

a B.A. degree in Environmental Studies from the University of Montana, and a Master’s of Forestry Degree in 

Sustainable Forest Management and Applied Economics from Oregon State University.

Chelsea P. McIver is a Research Specialist in the Forest Industry Research Program at the University of 

Montana’s Bureau of Business and Economic Research in Missoula, Montana. She holds a B.A. degree in 

Rural Sociology, and an M.S. degree in Forestry from the University of Montana.

Jim Menlove is an Ecologist and a member of the Information Management and Technology Team with the 

Interior West Inventory and Analysis Program at the Rocky Mountain Research Station in Ogden, Utah. He 

holds a B.S. degree in Biology from the University of Utah and an M.S. degree in Zoology and Physiology from 

the University of Wyoming, both with an emphasis in ecology.

Todd A. Morgan is the Director of the Forest Industry Research Program at The University of Montana’s 

Bureau of Business and Economic Research in Missoula, Montana. He holds a B.A. degree in Philosophy and 

a B.S. degree in Forest Science from The Pennsylvania State University, and an M.S. degree in Forestry from 

the University of Montana.

Chris Witt is an Ecologist and a member of the Analysis Team with the Interior West Forest Inventory and 

Analysis Program at the Rocky Mountain Research Station in Ogden, Utah. He holds B.S. and M.S. degrees in 

Ecology from Idaho State University.
ii

Report Highlights

Forest Area

• Wyoming’s forest land area totals 10.5 million acres.

• Unreserved forest land accounts for most of the forest land in Wyoming (68 percent) and totals approximately 7.2 million acres.

• Approximately 75 percent, or 5.4 million acres, of Wyoming’s unreserved forest land is classified as timberland and the remaining 25 percent is classified as unproductive forest land.

• About 56 percent of Wyoming’s total forest land area, or 5.8 million acres, is administered by the USDA 

Forest Service.

• About 15 percent of Wyoming’s total forest land area, or 1.6 million acres, is administered by the National 

Park Service.

• Privately owned forest land totals 1.5 million acres, or about 14 percent of Wyoming’s forest land area.

• The Fir/spruce/mountain hemlock forest-type group is the most extensive, covering 2.9 million acres, or 

27.8 percent of Wyoming’s forest land.

• The second most abundant forest-type group is Lodgepole pine, which encompasses over 2.5 million 

acres, or 24 percent of Wyoming’s forest land.

Forest Growth, Mortality, and Removals

• Gross annual growth of all live trees 5.0 inches in diameter and larger on Wyoming forest land totaled 270.4 

million cubic feet.

• Average annual mortality of trees 5.0 inches in diameter and larger totaled about 578.3 million cubic feet.

• Average annual net growth totaled -307.9 million cubic feet.

• The leading cause of mortality in Wyoming was insects, which resulted in approximately 16 million cubic 

feet of mortality in the Fir/spruce/mountain hemlock forest-type group, and another approximately 10 million 

cubic feet in the Lodgepole pine forest-type group.

• Mortality exceeded gross growth for six of the eight tree species with the greatest volume in Wyoming, including, lodgepole pine, Engelmann spruce, whitebark pine, Douglas-fir, limber pine, and aspen.

• Total removals in 2014 were nearly 25 million cubic feet, of which about 20.8 million cubic feet included 

timber products.

Numbers of Trees, Volume, and Biomass

• There are an estimated 4.6 billion live trees greater than 1.0 inch in diameter in Wyoming.

• Softwood species total 4.3 billion, or 94 percent of all live trees.

• The most abundant tree species is lodgepole pine with nearly 1.8 billion trees, accounting for 39 percent of 

live trees in Wyoming.

• Growing stock volume on timberland in Wyoming totals 8.7 billion cubic feet.

• The net volume of sawtimber trees on Wyoming forest land is 33.6 billion board feet.

• The aboveground weight for all live trees greater than 1.0 inch in diameter on Wyoming forest land is 256 

million tons of oven-dry biomass.
Current Issues in Wyoming’s Forests

• About 8 percent of Wyoming’s forest land occurs in stands older than 200 years.

• Approximately 416,000 acres of forest land in Wyoming could be classified as potential Canada lynx habitat.

• There are over 2.4 million acres in Wyoming that include some component of whitebark pine, and they have 

experienced an average annual net volume loss of 57.5 million cubic feet per year.

• Snags suitable for a large number of cavity-nesting birds can be found across the range of forest types and 

age classes in Wyoming.

• Invasive weeds were found on 12.4 percent of forest land in Wyoming, and Canada thistle accounted for 

60 percent of those occurrences.

• Average aspen volume (cubic feet per acre) has increased over the first 5 years of the annual inventory.

• From 1988 to 2015, nearly 2 million acres of Wyoming have burned, 41 percent on forest land and 59 percent on nonforest land.

• A large amount of National Forest System forest land area has been classified as unsuitable for timber 

production. While there are over a million acres suitable for timber production on NFS land in Wyoming, 

roughly one-fourth falls within the inventoried roadless designation.

• Juniper ages in the Rocky Mountain juniper and Pinyon/juniper forest types primarily occur in the 50-149 

year age class, whereas a much higher proportion (over 45 percent) of younger-aged juniper occur in other 

forest-type groups.

Acknowledgments

We would like to thank the Colorado State Forest Service field staff and the Interior West Forest Inventory and 

Analysis field crews who collected the inventory field data for Wyoming. We extend special thanks to private 

landowners who graciously allowed our crews access to field plots located on their lands. Special thanks to 

Trey Schillie for helping in the procurement of National Forest System roadless, wilderness, and suitable timber 

base layers for Regions 2 and 4. We acknowledge the invaluable cooperation and assistance of the Rocky 

Mountain and Intermountain Regions, Forest Service, U.S. Department of Agriculture; the Wyoming State Land 

Department; the Bureau of Land Management; the Bureau of Indian Affairs; the National Park Service; and the 

U.S. Department of the Interior.

iii
Contents

Introduction............................................................................................................................... 1

Wyoming’s Annual Forest Inventory ....................................................................................................................1

Previous Inventories of Wyoming’s Forests ..........................................................................................................1

Overview of Standard and Supplemental Tables..................................................................................................3

Accessing Wyoming’s Forest Inventory Data........................................................................................................3

Inventory Methods..................................................................................................................... 4

Sample Design....................................................................................................................................................4

Three-Phase Inventory.........................................................................................................................................4

Plot Configuration...............................................................................................................................................8

Sources of Error...................................................................................................................................................9

Quality Assurance.............................................................................................................................................10

Overview of Wyoming’s Forests............................................................................................... 14

Ecoregion Provinces of Wyoming......................................................................................................................14

Forest Land Classification..................................................................................................................................16

Forest Land Ownership .....................................................................................................................................17

Forest Types and Forest-Type Groups.................................................................................................................18

Forest Growth, Mortality, and Removals............................................................................................................19

Numbers of Trees..............................................................................................................................................23

Live and Dead Tree Volume and Biomass..........................................................................................................24

Stand Age .........................................................................................................................................................27

Stand Density Index..........................................................................................................................................28

Periodic to Annual Inventory Comparisons........................................................................................................31

Wyoming Forest Attribute Change.....................................................................................................................32

Wyoming’s Forest Resources.................................................................................................... 37

Removals for Timber Products...........................................................................................................................37

Wyoming’s Timber Industry...............................................................................................................................42

Canada Lynx Habitat.........................................................................................................................................43

Whitebark Pine Status and Trends .....................................................................................................................46

Snags as Wildlife Habitat ..................................................................................................................................52

Understory Vegetation.......................................................................................................................................55

Invasive and Noxious Species...........................................................................................................................57

Current Issues in Wyoming’s Forests ........................................................................................ 59

Bark Beetle Infestation ......................................................................................................................................59

Spruce Beetle....................................................................................................................................................59

Mountain Pine Beetle........................................................................................................................................60

Aspen Status and Trends....................................................................................................................................62

Fire in Wyoming’s Forests..................................................................................................................................64

National Forest System Inventory ......................................................................................................................68

Pinyon/Juniper Forest-Type Group.....................................................................................................................71

Conclusions.............................................................................................................................. 74

References ............................................................................................................................... 76

Appendix A: Standard Forest Inventory and Analysis Terminology ........................................... 84

Appendix B: Standard Forest Resource Tables.......................................................................... 92

Appendix C: Wyoming Forest-Type Groups and Forest Types, With Descriptions and 

Timber (T) or Woodland (W) Designations......................................................................... 128

Appendix D: Tree Species Groups and Tree Species Measured in the Wyoming Annual 

Inventory With Common Name, Scientific Name, and Timber (T) or Woodland (W) 

Designation........................................................................................................................ 131

Appendix E: Volume, Biomass, and Site Index Equation Sources—Wyoming ......................... 132

iv
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 1

Introduction

Wyoming encompasses a wide variety of forest types and tree species that 

are valued for their scenic beauty, wood products, wildlife habitat, and ecological 

functions. This report contains highlights of the status of Wyoming’s important 

forest resources, with a discussion of pertinent issues based on the first 5 years of 

inventory data. As a result, for the first time, forest scientists, managers, policymakers, and users have access to the first half of inventory data for Wyoming collected under the new Forest Inventory and Analysis (FIA) annual system (Gillespie 

1999).

Wyoming’s Annual Forest Inventory

In 1998, the Agricultural Research Extension and Education Reform Act, 

also known as the Farm Bill, mandated that inventories would be conducted 

throughout the forests of the United States on an annual basis. The annual forest inventory of Wyoming’s forests follows sampling procedures specified by this 

Federal legislation and the national FIA program. The annual system integrates 

FIA and Forest Health Monitoring (FHM) sampling designs into a mapped-plot 

design that includes: a systematic national sampling design consisting of one plot 

per approximately 6,000 acres; a nationally consistent plot configuration with four 

fixed-radius subplots; annual measurement of a constant proportion of permanent 

plots; data or data summaries within 6 months after completion of yearly sampling; 

and a State summary report following 5 years of sampling. The inventory sampling 

design for the Western United States involves the measurement of 10 systematic 

samples, or subpanels, where one subpanel is completed each year resulting in the 

measurement of all subpanels over a 10-year period. Each subpanel is pre-assigned 

to be surveyed during a specific calendar year, which is referred to as an inventory 

year (see Appendix A for standard FIA terminology). The year in which each plot 

was actually surveyed is recorded as its measurement year.

Interior West Forest Inventory and Analysis first implemented the annual 

inventory in Wyoming in 2011. This report is based on the aggregated data collected over 5 measurement years, 2011–2015, or 50 percent of the full cycle. The 

aggregated dataset includes a total of 5,271 plots, where: 858 (16.3 percent) plots 

contained at least one forested condition; 4,283 plots (81.3 percent) were entirely 

nonforest; and 130 plots (2.4 percent) were not sampled.

Previous Inventories of Wyoming’s Forests

Prior to the implementation of the annual inventory, three plot-based periodic 

inventories were conducted in Wyoming. During the first two inventories, estimates of forest land area were based solely on photo-interpretation and mapping 

of forest attributes using aerial photography, and estimates of wood volume were 

based on measurements collected on ground plots. The first periodic inventory was 

conducted in the late 1950s (Choate 1963). This inventory used interpretation of 
2 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

aerial photographs to produce map-based estimates of forest land area across all 

ownership groups. Volume estimates were based on ground measurements from 

more than 1,100 plots on commercial forest lands (Choate 1963), although the data 

from these plots are not available in the FIA database. A second periodic inventory 

was conducted in 1983 on all ownership groups except for national forests, each of 

which conducted their own inventories at that time, and on reserved lands including National Parks (Green and Conner 1989). Like the first inventory, this report 

estimated forest land area using aerial photographic interpretation combined with 

a dot-grid. Volume estimates were also estimated from plot measurements. More 

than 7,000 plots were field-measured, although only about 500 were forested, and 

20 percent of these occurred on timberland (Green and Conner 1989).

The third and final periodic inventory was conducted across all ownership 

groups between 1998 and 2002 (Thompson et al. 2005). This inventory differed 

from the two earlier periodic inventories in two important ways. First, it was based 

on the same probabilistic sample design that is used for the annual forest inventory, 

which was already being implemented in other States at that time. The shift from 

a sample design that targeted commercial timberland to a probabilistic sample 

of all forest lands, including woodlands and unproductive and/or reserved forest 

lands, produced apparent declines in tree volume; however, these apparent declines are largely due to the change in sample design (Goeking 2015). Second, the 

1998–2002 periodic inventory also used the same fixed-radius subplot configuration that is currently used in the annual inventory; however, the location of the microplot changed. Regional forest assessments using the 1998–2002 periodic data 

within Wyoming have been conducted, including the Black Hills National Forest 

(DeBlander 2002), the Shoshone National Forest (Menlove 2008), the Medicine 

Bow National Forest (Steed 2008), and the Bighorn National Forest (Witt 2008).

Ground-based plot data from the periodic inventories of the 1980s and 1998–

2002 are available in the national FIA database, FIADB (O’Connell et al. 2015). 

FIADB includes a data structure that designates specific groups of plots for producing estimates of forest attributes, such as forest land area and tree volume, associated with particular time periods. This data structure is known as an evaluation, 

and each plot’s nominal inventory year generally links it to a particular evaluation 

(O’Connell et al. 2015). For example, this report is based on the 2015 evaluation, 

which includes plots scheduled for measurement from 2011 to 2015. Prior to the 

annual inventory, measurements were not collected every year, so the evaluations 

for individual periodic inventories use nominal inventory years that may be very 

different from the actual years when the plots were measured. For example, the 

1983 inventory is assigned a 1984 inventory year although plots were measured in 

1983, 1984, 1992 and 1994. The 1998–2002 periodic inventory is assigned a nominal inventory year of 2000 in FIADB; however, here it is referred to as the 2002 

inventory to be consistent with the previous State report (Thompson et al. 2005).

Although the nominal inventory years and evaluations described above can 

be used to query periodic inventory data from FIADB, we strongly recommend 

against making broad-scale comparisons of periodic inventory data to annual 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 3

inventory estimates. Goeking (2015) demonstrated that comparing broad-scale estimates of forest attributes between periodic and annual inventories may lead to erroneous conclusions, compared to changes detected from consistent samples over 

time. The Periodic to Annual Inventory Comparisons section describes a method 

for making appropriate use of periodic inventory data to assess temporal changes 

in forest attributes.

Overview of Standard and Supplemental Tables

Forest Inventory and Analysis produces a set of standard tables using both 

Phase 2 and Phase 3 data (see the Three-Phase Inventory section below). Annual 

forest inventory data collected in Wyoming between 2011 and 2015 are summarized 

in Appendix B (tables B1–B37) in terms of traditional FIA attributes. Statistical 

estimates for land area, numbers of trees, wood volume, biomass, growth, mortality, and sampling errors are presented in these tables. Only in table B1 are all 

land cover types included, which are summarized by the proportions of sample 

plots that were recorded as forest, nonforest, and nonsampled (e.g., due to inaccessibility). All other tables in Appendix B exclude nonforest land and therefore 

include only accessible forest land or timberland (see Appendix A for definitions). 

This report also contains supplemental tables within the text. To avoid confusion 

between supplemental tables and standard tables (Appendix B), we labeled tables 

in the body of the report consecutively as they appear. Standard FIA tables will be 

referred to beginning with the appendix letter followed by the table number (e.g., 

table B1).

Accessing Wyoming’s Forest Inventory Data

FIA data are publicly available from the national FIA website at https://fia.

fs.fed.us. This site includes data downloads; online tools that allow users to perform custom queries; and documentation of FIA’s field inventory protocols, database structure, and publications. For assistance with finding information on this 

site or with performing custom analyses, data users are encouraged to contact one 

of the members of the Analysis Team of the Interior West FIA Program who are 

listed as authors at the beginning of this report.

The national FIA database contains data from the 1984 and 2000 periodic inventories as well as the annual forest inventory data, which is updated each 

year as additional measurements are collected. Data collected as part of the annual inventory is assigned an inventory year that corresponds to the year in which 

the plot was scheduled to be measured on a 10-year remeasurement cycle. The 

FIA database supports six possible evaluation periods for Wyoming (1984, 2000, 
4 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

2011–2012, 2011–2013, 2011–2014, and 2011–2015). FIA data may be downloaded in table form or summarized using a variety of online tools (http://fia.fs.fed.us/

tools-data/default.asp).

Inventory Methods

An important part of the FIA program is a nationally consistent sampling and 

inventory design. Here we briefly describe the major components of the design: 

national plot sample design; the three-phase inventory system; configuration of 

field plots; and possible sources of error, which are consistent among all States. We 

also describe FIA’s quality assurance program and present quality assessment results for the current Wyoming forest inventory and a comparison across all Interior 

West States. For additional information regarding the design and implementation 

of the annual inventory, see McRoberts et al. (2005) and Smith (2002).

Sample Design

Based on historic standards, a sampling intensity of approximately one plot 

per 6,000 acres is necessary to satisfy national FIA precision guidelines for area and 

volume. Therefore, FIA divided the area of the United States into non-overlapping, 

5,937-acre hexagons and established one plot in each hexagon using procedures 

designed to preserve existing plot locations from previous periodic inventories. 

These sample plots, designated as the Federal base sample, were divided into five 

spatially interpenetrating panels and 10 subpanels, where each panel consists of 

two subpanels. In the Eastern United States, two subpanels are measured each year 

such that the inventory cycle is on a 5-year rotation, while in the Western United 

States, including Wyoming, one subpanel is measured each year and inventory 

cycles are completed on a 10-year rotation (Gillespie 1999). For estimation purposes, the measurement of each subpanel of plots can be considered an independent, equal probability sample of all lands in a State, or all plots can be combined 

to represent the State.

Three-Phase Inventory

FIA conducts inventories in three phases. In Phase 1, remote sensing data are 

digitally analyzed to stratify each State into homogeneous groups such as forest 

and nonforest areas. Phase 2 relates to a permanent network of ground plots, where 

traditional inventory variables such as forest type and tree diameter are measured. 

In Phase 3, additional variables associated with forest and ecosystem health are 

measured on a subset of Phase 2 plots.

Phase 1

Phase 1 uses remote sensing data to delineate homogeneous areas, or strata, 

throughout the entire State. Currently in the Interior West, only forest and nonforest strata are identified. The purpose of this delineation is to reduce the variance of 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 5

FIA estimates through post-sampling stratification of field data. The initial Phase 1 

strata map consisted of forest, nonforest, and census water strata (see Appendix A 

for definitions), which were delineated at a spatial resolution of 250 meters using 

a combination of 2004 MODIS satellite imagery, other geospatial datasets, and 

plot-based calibration data (Blackard et al. 2008). Calibration data in Wyoming 

consisted of periodic plot locations that had been classified as forest, nonforest, or 

census water, based on field surveys or human interpretation of aerial photographs 

prior to 2011. In Wyoming, the census water stratum and nonforest stratum are 

combined.

In most Interior West States, post-sampling stratification is based solely on 

forest and nonforest strata under the assumption that any Phase 2 nonresponse 

plots occur randomly across the plot grid. Nonresponse plots are defined as plot 

locations that cannot be sampled by a field crew. They typically occur when landowners or managers do not grant permission for field crews to access plot locations 

on their lands, although some plots are not sampled due to hazardous conditions 

that may be permanent in nature (e.g., sheer cliffs) or temporary hazards (e.g., 

current wildfires or active logging operations). When nonresponse plots do not occur randomly across the plot grid, the estimates of forest attributes may be biased 

(Patterson et al. 2012). The nonresponse rate in Wyoming’s forest inventory for the 

period 2011 through 2015 was relatively low at 2.5 percent. When large, the magnitude of the effect of nonresponse on forest estimates can be estimated (Goeking 

and Patterson 2013), but for the purpose of this report, the effect is assumed to be 

small.

FIA produces estimates at the scale of individual States, which can then be 

aggregated into regional estimates, as well as at smaller scales within each State. 

Within-State population estimates are constructed at two scales: survey units that 

are comprised of groups of counties, and smaller estimation units that represent individual counties. Wyoming consists of three survey units (i.e., groups of counties) 

and 23 estimation units (i.e., counties) denoted as g, each containing ng ground 

plots. The area of each estimation unit is divided into strata of known size using the 

State’s stratification map, which divides the total area of the estimation unit into 

250-meter pixels and assigns each pixel to one of H strata. Each stratum, h, within 

an estimation unit, g, then contains nhg ground plots where the Phase 2 attributes 

of interest are observed.

To illustrate, the area estimator for forest land within an estimation unit in 

Wyoming is defined as:

Âg = ATg Σ

H

h=1

Whg

Σ yihg

i=1

nhg

nhg

where:

Âg = total forest area (acres) for estimation unit g
6 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

ATg = total land area (acres) in estimation unit g

H = number of strata

Whg = proportion of Phase 1 pixels in estimation unit g that occur in stratum h

yihg = forest land condition proportion on Phase 2 plot i in stratum h in estimation unit g

nhg = total number of Phase 2 plots in stratum h in estimation unit g

Phase 2

The second phase pertains to FIA’s network grid of permanent plot locations, 

each assigned spatial coordinates, and representing approximately 6,000 acres. To 

minimize inventory costs, we do not estimate plots that are obviously and entirely 

nonforest for field sampling, and these plots are recorded as nonforest. A human 

interpreter examines each plot location using digital imagery from the National 

Agriculture Imagery Program and distinguishes plots that potentially contain forest or wooded land from those that do not intersect any forest or wooded land. This 

process is known as prefield interpretation, and it was historically considered part 

of Phase 1 because both prefield interpretation and Phase 1 relied on remote sensing data. However, Phase 1 delineation of forest and nonforest strata occurs independently of current prefield interpretation of the Phase 2 grid. Therefore, prefield 

data collection is now considered part of Phase 2 and not part of Phase 1.

The status of each plot in the Phase 2 grid is assigned as accessible forest land, 

nonforest land, or not sampled (see Appendix A for definitions). Plots that were not 

designated for field sampling by prefield interpreters are automatically recorded as 

nonforest plots. For plots that are designated for field sampling, field crews record 

the plot status as accessible forest land if (a) they can physically visit the plot location, and (b) the plot satisfies FIA’s definition of forest land based on field measurements (see Appendix A). Some field plots are recorded as nonforest because the 

field crew determines that they do not meet FIA’s definition of forest land. A field 

plot may be recorded as nonsampled if a field crew cannot safely measure the plot 

or if they cannot obtain permission to access the plot location. Before visiting plot 

locations, FIA crews identify each plot’s ownership status by consulting county land 

records and then seek permission from private landowners to measure plots on their 

lands. Information about individual landowners and the existence of FIA plots on 

their property is considered confidential and is never shared with anyone, regardless 

of whether permission to access the plot location is granted. The total percentage of 

Phase 2 plot areas that represent forest, nonforest, and nonsampled (response) conditions can be found in table B1 (Appendix B; fig. 1).

Field crews record a variety of data on Phase 2 plots that contain accessible 

forest land. Crews locate the geographic center of the plot using geographic positioning system receivers and then establish markers to facilitate relocation of the 

plot for future remeasurement. They record condition-level variables that include 

land use, forest type, stand origin, stand-size class, stand age, site productivity 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 7

class, forest disturbance history, silvicultural treatment, slope, aspect, and physiographic class. Some of these area attributes are measured or observed (e.g., regeneration status), some are assigned by definition (e.g., ownership group), and 

some are subsequently computed from tree data (e.g., percent stocking). For each 

tree on the plot, field crews record a variety of attributes including species, live/

dead status, diameter, height, crown ratio, crown class, damage, and decay status. 

The field procedures used in Wyoming’s forest inventory are described in detail 

in the FIA field guide (USFS 2013). Data analysts apply statistical models using 

field measurements to calculate additional variables such as volume and biomass 

for individual trees, as well as volume, biomass, growth, mortality, and number of 

trees per unit area.

Figure 1—Plot status of the 5,271 Phase 2 plots in Wyoming’s annual forest inventory, 2011–2015. (Note: plot locations are approximate; some plots on private land were randomly swapped.) 
8 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Phase 3

The third phase of the FIA program inventory focuses on forest and ecosystem health. The Phase 3 sample consists of a 1/16 subset of the Phase 2 

plots, which equates to one Phase 3 plot for approximately every 96,000 acres. 

Nationally, Phase 3 plots include all the measurements collected on Phase 2 plots, 

plus an extended suite of measurements to characterize down woody materials, 

lichen communities, tree crowns, and understory vegetation structure. Phase 3 

measurements are obtained by field crews during the growing season. The entire 

suite of Phase 2 measurements is collected on each Phase 3 plot at the same time 

as the Phase 3 measurements. In the Interior West down woody material and understory vegetation structure are collected on all Phase 2 plots.

Plot Configuration

The national FIA Phase 2 plot design consists of four 24-foot radius subplots configured as a central subplot and three peripheral subplots (USFS 2013; 

fig. 2). Centers of the peripheral subplots are located at distances of 120 feet and 

at azimuths of 360 degrees, 120 degrees, and 240 degrees from the center of the 

central subplot. Each standing tree with a diameter at breast height (d.b.h.) for 

timber trees, or a diameter at root collar (d.r.c.) for woodland trees (Appendix 

A), of 5.0 inches or larger is measured on these subplots. Each subplot contains 

a 6.8-foot radius microplot with its center located 12 feet at 90 degrees from the 

Figure 2—Plot configuration used by the Forest 

Inventory and Analysis program. Each plot consists 

of four subplots with a 24-foot radius. The three 

outer subplots are located 120 feet from the central 

subplot’s center at azimuths of 360 (0), 120, and 

240 degrees. Microplots with radii of 6.8 feet are 

located on each subplot, and the microplot centers 

are located 12 feet from the subplot center at an 

azimuth of 90 degrees. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 9

subplot center on which each tree with a d.b.h./d.r.c. from 1 inch to 4.9 inches is 

measured and seedlings are tallied by species.

To enable division of the forest into various units of interest for analysis, it 

is important that the tree data recorded on these plots are properly associated with 

stand-level data. In addition to the tree data recorded on FIA plots, data are also 

gathered about the condition class in which the trees are located. A condition class 

(or condition) is the combination of discrete landscape and forest attributes that 

define and describe the area associated with a plot. The six variables that define 

distinct condition classes are forest type, stand origin, stand size, ownership group, 

reserved status, and stand density (Bechtold and Patterson 2005; USFS 2013). In 

some cases, the plot footprint spans two or more conditions if there is a distinct 

change in any of these six variables. For example, the four subplots on a plot may 

intersect both forest and nonforest areas, the plot may include distinct stands differentiated by forest type and/or stand size, or the plot may straddle a boundary between two different ownership groups. All three of these examples would result in 

more than one condition per plot. Field crews assign numbers to condition classes 

in the order they are encountered on a plot. Each tree is assigned the number of the 

condition class in which it stands to enable partitioning of tree data into meaningful categories for analysis.

Sources of Error

Sampling Error

The process of sampling (selecting a random subset of a population and calculating estimates from this subset) causes estimates to contain errors they would 

not have if every member of the population had been observed. The 2011–2015 

FIA inventory of Wyoming is based on a sample of 5,141 plots (not including 

130 nonresponse plots) systematically located across the State. The total area of 

Wyoming is 62.6 million acres, so the sampling rate is approximately one plot for 

every 12,176 acres. The sampling rate will decrease as the next 5 years of annual 

data are collected.

The statistical estimation procedures used to provide the estimates of the 

population totals presented in this report are described in detail in Bechtold and 

Patterson (2005). Along with each estimate is an associated sampling error that is 

typically expressed as a percentage of the estimated value, but it can also be expressed in the same units as the estimate or as a confidence interval (the estimated 

value plus or minus the sampling error). Sampling error is the primary measure of 

the reliability of an estimate. An approximate 67 percent confidence interval constructed from the sampling error can be interpreted to mean that under hypothetical 

repeated sampling, approximately 67 percent of the confidence intervals calculated 

from the individual repeat samples would include the true population parameter 

if it were computed from a 100-percent inventory. Wyoming sampling errors for 

State-level estimates of area, volume, net growth, and morality at the 67 percent 

confidence level are presented in table B37.
10 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Because sampling error increases as the area or volume considered decreases, users should aggregate data categories as much as possible. Sampling errors 

obtained from this method are only approximations of reliability because homogeneity of variances is assumed. Users may compute statistical confidence for 

subdivisions of the reported data using FIA’s estimation tools (http://fia.fs.fed.us/

tools-data/default.asp).

Measurement Error

Measurement errors are errors associated with the methods and instruments 

used to observe and record the sample attributes. On FIA plots, attributes such as 

the diameter and height of a tree are measured with specialized instruments, and 

other attributes such as species and crown class are observed without the aid of 

an instrument. On a typical FIA plot, 30 to 70 trees are observed with 15 to 20 attributes recorded on each tree. In addition, many attributes that describe the plot 

and conditions on the plot are observed. Errors in any of these observations affect 

the quality of the estimates. If a measurement is biased—such as diameters consistently taken at a height other than 4.5 feet from the ground—then the estimates 

derived from this observation (e.g., volume) will reflect this bias. Even if measurements are unbiased, high levels of random error in the measurements will add to 

the total random error of the estimation. To ensure that FIA observations meet the 

highest standards possible, a quality assurance program, described below, is integrated throughout all FIA data collection efforts.

Prediction Error

Prediction errors are associated with using mathematical models (such as 

volume equations) to provide information about attributes of interest based on 

sample attributes. Area, number of trees, volume, growth, removals, and mortality 

are the primary attributes of interest presented in this report. FIA estimates of area 

and number of trees are based on direct observations and do not involve the use of 

prediction models; however, estimates of volume, biomass, growth, and mortality use model-based predictions in the estimation process and are thus subject to 

prediction errors.

Quality Assurance

FIA employs a Quality Assurance (QA) program to ensure the integrity of all 

collected data. The QA program provides a framework to assure the production of 

complete, accurate, and unbiased forest information of known quality. There are 

two primary facets of FIA’s QA program: quality control and quality assessment.

Quality control is the first facet of FIA’s QA program, and it occurs throughout field data collection and compilation. The field aspect of quality control is 

conducted by data quality inspectors, who assess individual field crews and then 

provide timely feedback to improve the crews’ performance. This is accomplished 

by means of hot checks and cold checks. During a hot check, an inspector accompanies a field crew to a plot and provides immediate feedback on the quality of 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 11

their measurements. Cold checks occur when an inspector visits a recently completed plot, typically in possession of the original crew’s data but without the crew 

present, and then verifies each measurement and provides the crew an overall score 

as well as feedback on measurements that did not meet FIA specifications. On average, hot checks are done on 2 percent of all field-sampled plots and cold checks 

are done on 5 percent of field-sampled plots. Quality control is also accomplished 

via programming of portable data recorders that check for complete, valid, and 

reasonable values during data collection. Following data collection, information 

management specialists conduct further logic checks and investigate any unexpected, missing, or inconsistent values.

Quality assessment is the second facet of FIA’s QA program, and this process 

quantifies the overall precision of field measurements by comparing two independent measurements of the same plot. The independent measurements are collected 

by means of blind checks, where a regular field crew collects measurements and 

then a second crew collects a second set of measurements, without knowledge of or 

access to the first crew’s measurements (Pollard et al. 2006). Thus, these paired observations provide a means of assessing repeatability of FIA’s field measurements.

Quality control and quality assessment both require a data quality standard 

that defines the target level of precision for field measurements. FIA has specific 

Measurement Quality Objectives (MQOs) that enumerate data quality standards 

for individual field-measured variables. These data quality objectives were developed from knowledge of forestry measurement approaches as well as the requirements of the FIA program. MQOs for each variable consist of a measurement 

tolerance and a compliance standard. Measurement tolerances define the acceptable range of variability between two independent observations, and compliance 

standards define the target percentage of observations that should be within the 

measurement tolerance when recorded by two independent observers. The practicality of these MQOs, as well as the measurement uncertainty associated with a 

given field measurement, can be tested by comparing the results of quality assessments using blind check data.

Quality assessment data for Wyoming’s current inventory were collected between 2011 and 2015 from 28 plots comprising 35 conditions and 762 trees. The 

results of the quality assessment analysis for this period are presented in tables 1 

and 2. Each variable and its associated measurement tolerance are followed by the 

percentage of total paired records that fall within one, two, three, and four times 

the tolerance. The last four columns show the number of observations that fell 

outside the tolerance. For example, table 1 shows that there were 35 conditions 

that were measured independently by two field crews. For the variable “Forest 

Type,” about 97 percent of those conditions fell within the tolerance of having 

no errors. The percentage of observations that fall within the 1x tolerance level is 

referred to as the observed compliance rate, which can be compared to the compliance standard for each variable’s MQO to determine that variable’s performance. 

Compliance standards and measurement tolerances for FIA’s field measurements 

are listed within the field manual (USFS 2011).
12 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Results indicate variables have varying degrees of repeatability (tables 1 and 

2). For example, one condition-level regional variable that appears to be fairly repeatable is “percent bare ground” (table 1). At the 1x tolerance level, its observed 

compliance rate was about 94 percent. This represents that 94 percent of 32 paired 

observations were within plus or minus 10 percent of each other. In contrast, the 

compliance rate for “percent crown cover,” which has ±10 percent tolerance variability, was only 65 percent. This low compliance rate warrants further investigation into the potential repeatability issues associated with evaluating tree crown 

cover, which is typically done using four transects per subplot (USFS 2011).

The tree measurements that have the biggest influence on estimates of forest volume are species, diameter, and height. As shown in table 2, the compliance 

rate for the variable “Species” was 99 percent. The variables “diameter at breast 

height” and “diameter at root collar” represent the respective diameters of timber 

and woodland tree species (Appendix D). Whereas timber species are measured at 

breast height (4.5 feet above ground level), woodland species are measured near 

ground level at root collar. The 1x compliance rate was almost 91 percent for both 

d.b.h., which has a 0.1-inch tolerance, and d.r.c., which has a 0.2-inch per stem tolerance. The tolerance for root collar diameter is plus or minus 0.2 inches per stem, 

which allows for larger tolerances on multi-stemmed woodland trees. Tree height 

is represented by the variables “total length” and “actual length.” Both variables 

Table 1—Results of quality assessment for condition-level variables, Wyoming, 2011–2015. 

Variable Tolerance

Percentage of data within

tolerance

Number of times data exceeded 

tolerance

@1x @2x @3x @4x @1x @2x @3x @4x Records

National core variables

Condition status No errors 97.1 - - - 1 - - - 35

Reserve status No errors 100.0 - - - 0 - - - 35

Owner group No errors 100.0 - - - 0 - - - 35

Forest type No errors 96.9 - - - 1 - - - 32

Stand size No errors 87.5 - - - 4 - - - 32

Regeneration status No errors 96.9 - - - 1 - - - 32

Tree density No errors 100.0 - - - 0 - - - 32

Disturbance 1 No errors 81.8 - - - 6 - - - 33

Disturbance year 1 ±1 year 54.5 72.7 72.7 72.7 5 3 3 3 11

Treatment 1 No errors 97.0 - - - 1 - - - 33

Treatment year 1 ±1 year - - - - - - - - -

Physiographic class No errors 63.6 - - - 12 - - - 33

Regional variables

Percent crown cover ±10 % 65.4 96.2 96.2 100.0 9 1 1 0 26

Percent bare ground ±10 % 93.8 96.9 96.9 96.9 2 1 1 1 32

Habitat type 1 No errors 84.8 - - - 5 - - - 33

Habitat type 2 No errors 87.9 - - - 4 - - - 33
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 13

have a tolerance level of ±10 percent of the observed length, and compliance rates 

at the 1x level were about 90 percent and 89 percent, respectively.

Compliance rates that fall below compliance standards indicate variables for 

which either more intensive crew training is required, or that the variable’s MQO 

needs to be adjusted accordingly to better reflect the realistic expectation of quality 

for that variable. As a result, MQOs are used not only to assess the reliability of 

FIA measurements and their ability to meet current standards, but also to identify 

areas of improvement of data collection protocols and training. This ongoing process improves repeatability or may even lead to elimination of variables that prove 

Table 2—Results of quality assessment for tree-level variables, Wyoming, 2011–2015. 

Percentage of data within 

tolerance

Number of times data exceeded 

tolerance

Variable Tolerance @1x @2x @3x @4x @1x @2x @3x @4x Records

National core variables

Diameter at breast 

height ±0.1 /20 inch 90.7 96.0 97.1 97.2 70 30 22 21 751

Diameter at root collar ±0.2 in * no. 

stems 90.9 100.0 - - 1 0 - - 11

Azimuth ±10 o 97.2 98.8 99.2 99.2 21 9 6 6 762

Horizontal distance ±0.2 /1.0 feet 97.2 98.y 98.8 99.1 21 10 9 7 762

Species No errors 98.8 - - - 9 - - - 762

Tree status No errors 98.7 - - - 10 - - - 762

Rotten/missing cull ±10 % 96.0 99.0 99.9 100.0 28 7 1 0 699

Total length ±10 % 90.4 98.6 99.0 99.3 73 11 8 5 762

Actual length ±10 % 89.2 97.3 98.1 98.9 40 10 7 4 371

Compacted crown 

ratio ±10 % 100.0 - - - 0 - - - 490

Uncompacted crown 

ratio (p3) ±10 % 78.7 95.6 98.6 99.5 91 19 6 2 428

Crown class No errors 6.9 - - - 456 - - - 490

Decay class ±1 class 100.0 - - - 0 - - - 262

Cause of death No errors 87.2 - - - 25 - - - 195

Mortality year ±2 year 83.1 95.9 99.0 99.5 33 8 2 1 195

Condition class No errors 99.6 - - - 3 - - - 762

Regional variables

Mistletoe ±1 class 96.9 98.8 99.2 99.8 15 6 4 1 490

Number of stems ±1 stem 100.0 100.0 100.0 100.0 0 0 0 0 11

Percent missing top ±10 % 94.7 94.7 94.7 94.7 37 37 37 37 699

Sound dead ±10 % 64.1 64.1 64.1 64.1 251 251 251 251 699

Form defect ±10 % 43.1 43.1 43.1 43.1 82 82 82 82 144

Current tree class No errors 96.3 - - - 28 - - - 762

Tree age ±5 % 47.6 57.1 61.9 61.9 11 9 8 8 21
14 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

to be unrepeatable. For example, crown class was the least repeatable tree-level 

variable, with a 1x compliance rate of less than 7 percent; the 1x compliance rates 

for sound dead, form defect, and tree age also fell far below compliance standards 

(64 percent, 43 percent, and 48 percent, respectively). Quality assessment results 

from surrounding States (table 3) show that compliance rates for these four variables are typically low in States with high proportions of woodland forest types 

(Goeking et al. 2014; Menlove et al. 2017; Thompson et al. 2017; Werstak et al. 

2016), whereas their compliance rates are much higher in States with high proportions of timber types (Menlove et al. 2012; Witt et al. 2012). This discrepancy suggests that the following actions may improve the repeatability of these variables: 

(a) provide additional training for crews working in woodland forest types, and/or 

(b) adjust the variables’ definitions with respect to woodland trees.

The low compliance rate for the “Tree age” variable was observed in 

Wyoming and all other Interior West States and is probably due to the difficulty of 

obtaining accurate tree ages. Several factors that might contribute to inconsistency 

among tree ages are: (1) variation in age estimation when cores do not include tree 

center, or pith; (2) tree rings are too close together or too faint to read accurately 

in the field; and (3) trees are too large for increment borers to reach the center. 

These situations are particularly prevalent in the old and slow-growing trees that 

are typical in Wyoming’s forests, and they could be mitigated through better field 

procedures and/or processing tree cores in a dedicated tree-ring laboratory that 

uses sandpaper, microscopes, and sometimes modeling techniques to obtain more 

accurate age estimates. FIA is currently collecting a subsample of tree cores to 

be processed in a dedicated tree-ring laboratory, and this process will likely help 

increase the repeatability of FIA’s tree age variable in the future.

Overview of Wyoming’s Forests

Ecoregion Provinces of Wyoming

Ecological units characterize areas of similar vegetation, climate, soils, hydrologic processes, disturbance regimes, topography, geology, and other processes 

such as nutrient cycling and plant community succession (Cleland et al. 1997). 

Ecoregions in the United States are hierarchically subdivided, in descending order 

of extent, into domains, divisions, provinces, sections, and subsection. Provinces 

Table 3—Comparison of quality assessment results for select tree-level variables by States. Values are percent of observations with 

1x compliance rate. 

Variable Arizona Colorado Idaho Montana Nevada

New 

Mexico Utah Wyoming

Crown class 10.8 4.1 78.4 81.9 11.4 15.8 11.6 6.9

Sound dead 41.5 49.7 85.5 90.1 44.6 57.4 65.1 64.1

Form defect 59.8 11.2 95.4 93.6 na 67.7 61.6 43.1

Tree age 80.2 30.6 12.3 18.0 25.4 38.7 23.2 47.6
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 15

are defined largely by major floristic composition and are therefore the most relevant units for characterizing forested land. Elevation, landform, and climate are distinct drivers of the characteristic vegetation occupying each ecoregion. Wyoming 

is very dry, with a large portion of steppe environment centered in the semiarid 

west. The vast majority of annual precipitation at high elevations is delivered in 

the cool season (e.g., winter) and comes in the form of snow. Spatial variability in 

spring and summer rains at lower elevations helps explain the occurrence of a diversity of forest tree species throughout the region. The mountainous western portion of Wyoming receives summertime moisture from convective thunderstorms, 

whereas the eastern portion of the State is influenced by rainstorms originating 

from the Gulf of Mexico and the Great Plains throughout the year (Mock 1996).

Four ecoregion provinces cover Wyoming (fig. 3) and are discussed in decreasing area of coverage. The Intermountain Semi-Desert Province (342) encompasses a large portion of central Wyoming (44 percent of the State) but only 

includes 9 percent of the State’s forests. This ecoregion extends from the north 

in the Bighorn Basin, south to the Utah and Colorado border (fig. 3). The major 

vegetation in this province includes what is colloquially called sagebrush steppe, 

Figure 3—The four 

ecological provinces in 

Wyoming; background 

shows shaded relief and 

county boundaries. M331: 

Southern Rocky Mountain 

Steppe-Open WoodlandConiferous Forest-Alpine 

Meadow Province, M334: 

Black Hills Coniferous 

Forest Province, 331: 

Great Plains-Palouse Dry 

Steppe Province 342: 

Intermountain Semi-Desert 

Province. 
16 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

but it also includes the largest proportion of the State’s Pinyon/juniper forest-type 

group (624,000 acres).

The second most extensive province is the Great Plains-Palouse Dry Steppe 

Province (331), encompassing 25 percent of the State. The major vegetation that 

describes this province is shortgrass prairie characteristic of the Great Plains. 

Pinyon/juniper and Ponderosa pine forest-type groups make up the majority of 

forests present in this ecoregion, each accounting for approximately 37 percent.

Third, the Southern Rocky Mountain Steppe-Open Woodland-Coniferous 

Forest-Alpine Meadow Province (M331) encompasses the highest elevations and 

mountainous areas of Wyoming, including the Greater Yellowstone Ecosystem, 

the Bighorn Mountains, and the Medicine Bow-Routt National Forests in southeastern Wyoming (fig. 3). While this ecoregion covers only 25 percent of the 

State, 80 percent of the forested land occurs here.

Finally, the Black Hills Coniferous Forest Province (M334) encompasses 

a small area (1.7 percent) in the northeastern part of Wyoming that is generally 

higher in elevation than the surrounding Great Plains. Given the higher precipitation, the Black Hills support forested vegetation that is unique in that there are 

western, eastern, and boreal species present. Indeed, much of Wyoming’s forest 

tree diversity occurs in this ecoregion. For example, white spruce (Picea glauca) 

is present, and is typical of boreal forests much farther north. Ponderosa pine is 

the most abundant species in the Black Hills, representing 63 percent of the forested area, and represents the eastern edge of a genetic sub-species that has been 

rapidly expanding its range since the last glacial maximum (Norris et al. 2016). 

The presence of bur oak (Quercus macrocarpa) in the Black Hills represents the 

western edge of this typically eastern species.

Forest Land Classification

FIA uses a nationally consistent standard for defining different categories 

of forest land. These categories were originally developed for the purpose of separating forest land deemed suitable for timber production from forest land that 

was either not suitable or unavailable for timber harvesting activity. Reserved 

forest land is considered unavailable for any type of wood utilization management practice through administrative proclamation or legislation. Unreserved 

forest land is considered available for harvesting activity where wood volume 

can be removed for wood products. Unreserved forest land is further divided 

into timberland and unproductive forests. Timberland is forest land considered 

capable of producing at least 20 cubic feet of wood per acre per year from trees 

designated as a timber species and is not withdrawn from timber production. 

Unproductive forests are not capable of producing 20 cubic feet of wood per 

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

as a timber forest type, typically because of species and/or site conditions (see 

Appendix A for definitions). Reserved forest land can also be divided into productive and unproductive classes (table B2).
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 17

The State of Wyoming encompasses over 62.6 million acres. Seventeen 

percent, or 10.5 million acres (table B2), of the area meets the definition of forest land. Unreserved forest land accounts for 68 percent of the total forest land 

in Wyoming with 75 percent classified as timberland and 25 percent classified 

as unproductive. Approximately 32 percent of the forest land in Wyoming is reserved and almost 94 percent of this reserved forest land is classified as productive (table B2, and see National Forest System Inventory below).

Forest Land Ownership

The majority of forest land in Wyoming is administered by the USDA 

National Forest System (NFS), which manages 5.8 million acres (table B2). This 

represents almost 56 percent of the State’s total forest land area (fig. 4). NFS land 

in Wyoming consists of six different national forests and a National Grassland. 

Bridger-Teton National Forest and the Uinta-Wasatch-Cache National Forest of 

Region 4 occur in western Wyoming, and Shoshone National Forest, Bighorn 

National Forest, Black Hills National Forest, the Medicine Bow-Routt National 

Forest and the Thunder Basin National Grassland occur in Region 2. Seventy-one 

Figure 4—Distribution of 

inventory plots on forest 

land by ownership group, 

Wyoming, 2011–2015. 

(Note: plot locations are 

approximate; some plots on 

private land were randomly 

swapped.)
18 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

percent of NFS forest land is classified as unreserved forest land of which the majority (91 percent) is timberland (but see National Forest System Inventory below).

The National Park Service (NPS) is the second largest administrator of forest land in Wyoming, overseeing just over 15 percent that occurs primarily in 

Yellowstone National Park and Grand Teton National Park. Another agency that 

controls a significant amount of forest land in Wyoming is the Bureau of Land 

Management (BLM). Forest land administered by the BLM totals just over 1.1 

million acres, or 10 percent of the forest land in the State. The entirety of forest 

land under BLM jurisdiction is classified as unreserved, and almost 33 percent of 

BLM forest land meets the criteria for timberland. Privately owned forest land totals just over 1.1 million acres. Private landowners are a diverse group in Wyoming 

consisting of private individuals/families, tribes, unincorporated local associations, 

and corporations. All private forest land is in the unreserved owner class with 63.3 

percent classified as timberland and 36.6 percent classified as unproductive. The 

remaining forest land area in Wyoming is controlled by State and local government 

(3.4 percent), and the Department of Defense, U.S. Fish and Wildlife Service, and 

other Federal controlling less than 1 percent each.

Forest Types and Forest-Type Groups

Forest type is a classification of forested land based on the species forming a majority of live tree stocking in most cases. Names assigned to forest types 

may be based on a single species or groups of species. The distribution of forest 

types across the landscape is influenced by factors such as climate, soil, elevation, aspect, disturbance history, and succession. The loss or gain of a particular 

forest type over time can help assess the impact of successional changes, major 

disturbances related to fire, weather, climate, insects, disease, and human-caused 

disturbances such as timber harvesting or restoration.

The FIA program aggregates forest types into forest-type groups to simplify interpretation of large-scale forest trends nationally and by State. Forests in 

Wyoming are represented by 11 forest-type groups that are further classified into 

distinct forest types (see Appendix C). Some forest-type groups contain only one 

forest type, while other forest-type groups include several individual forest types. 

For example, a common forest-type group in Wyoming with multiple forest types 

is the Fir/spruce/mountain hemlock forest-type group, which consists of the Blue 

spruce forest type, the Engelmann spruce forest type, the Engelmann spruce/subalpine fir forest type, and the Subalpine fir forest type.

In Wyoming, the Fir/spruce/mountain hemlock forest-type group is the most 

extensive, covering 2.9 million acres, accounting for 27.8 percent of total forest 

area in the State (table B3). Within the Fir/spruce/mountain hemlock forest-type 

group, the Engelmann spruce/subalpine fir forest type accounts for nearly half the 

acreage (49.5 percent) and the Subalpine fir forest type accounts for another 33 

percent. The second most abundant forest-type group is Lodgepole pine, which encompasses over 2.5 million acres, almost 24 percent of the State’s forest land. The 

Lodgepole pine forest-type group consists of only the Lodgepole pine forest type. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 19

The Pinyon/juniper forest-type group is third in abundance at almost 1.1 million 

acres (10.3 percent), and is comprised primarily of the Rocky Mountain juniper 

forest type (54.4 percent) and the Juniper woodland forest type (43.6 percent). 

Fourth in abundance is the Nonstocked forest-type group at 0.86 million acres (8.2 

percent). The economically important Ponderosa pine (8 percent) and Douglas-fir 

(7.7 percent) forest-type groups each occupy approximately 0.8 million acres in 

Wyoming. The remaining forest land in the State is classified as: Other western 

softwoods forest-type group (6 percent), which includes the important wildlife 

species whitebark pine; the Aspen/birch forest-type group (5.9 percent); the Oak/

hickory forest-type group (1 percent), the Elm/ash/cottonwood forest-type group 

(0.7 percent), which occur primarily in the eastern portion of the State; and the 

Woodland hardwoods forest-type group (0.2 percent).

Forest Growth, Mortality, and Removals

To monitor changes in tree volume over time, the relationships between 

growth, mortality, and removals can be quantified. Growth is typically expressed 

as net growth and is defined as average annual net growth in tree volume minus 

the volume lost through mortality. Mortality is the average annual volume of trees 

dying over a given time period due to natural causes, and excludes the volume 

removed through harvesting. Tree mortality normally occurs at low, “background” 

rates due to insects and disease, competition, or advanced tree age. Occasionally, 

highly concentrated and relatively localized mortality occur due to insect and disease epidemics, wildfire, or severe weather events. Removals represent the net 

volume of growing-stock trees removed from the inventory by harvesting or other 

cultural operations (such as timber stand improvement), by land clearing, or by 

changes in land use (such as an administrative change to wilderness).

Ideally, growth, mortality, and removals would be analyzed using measurements of the same plot at two points in time. It is also possible to estimate growth 

and mortality rates based on a single inventory, as is described below. In contrast, removals cannot be reliably estimated without having two measurements 

of the same set of plots. Because of these differences in estimation procedures, 

growth and mortality are analyzed and discussed separately from removals (see the 

Removals for Timber Products section below). Average annual growth and mortality, as reported here, are estimated using the combination of two approaches, 

which depends on the remeasurement status of the plot. In Wyoming, the last complete periodic inventory (conducted from 1998 thru 2002) utilized the national 

mapped-plot design, and when implementation of the annual inventory began in 

2011, many of the same plots were incorporated into the grid. Of the 951 forested 

plots measured from 2011–2015 in Wyoming, 803 (84 percent) were established 

at the same locations as periodic inventory plots. The implications for this are that 

the remeasurement time period can be anywhere from 9 years (e.g., 2002–2011) 

to 17 years (e.g., 1998–2015), or any other combination in between, where the 

average remeasurement time period was 13.2 years. Therefore, average annual net 

growth on 84 percent of the plots is estimated using remeasurement data, whereas 
20 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

the remaining 16 percent of plots were calculated from 10-year radial increment, 

measured from ring widths sampled using increment bores, on plots during their 

first visit. Similarly, mortality, as reported here, is estimated using remeasurement 

data on 84 percent of the plots, and on the remaining plots, the average annual 

net volume of trees estimated to have died in the 5 years prior to the year of measurement, based on field calls was used. This extended remeasurement period, on 

average, can influence estimates of growth and mortality. Only when complete 

remeasurement for the State—where the status of the plot and all trees on the 

plot are known at two, pre-determined, points in time (10-year measurement interval)—will temporal trends of growth and mortality reflect the probabilistic nature 

of the annual sample design.

The annual estimate of gross growth of all live trees 5.0 inches diameter 

and greater on forest land in Wyoming totaled nearly 270.4 million cubic feet 

(MMCF). This is the sum of growth on all survivor and ingrowth trees. Survivor 

trees are live trees 5.0 inches and larger in diameter 10 years before the current 

measurement. Ingrowth trees are live trees 5.0 inches and larger in diameter that 

grew over the 5.0-inch threshold during the previous 10 years. While this annual 

increase appears large in absolute terms, it is relatively small; average annual net 

growth as a percentage of net volume of all live trees 5.0 inches and larger in diameter was approximately -2 percent per year, and has been averaging about -2 

percent over the annual inventory (fig. 5). These data suggest that relatively high 

levels of tree mortality are currently drawing down live tree growing stock.

The average annual mortality of trees 5.0 inches in diameter and larger on 

forest land in Wyoming was 578.3 MMCF (table B25). The difference between 

the live tree, or gross growth and mortality indicates an average annual net growth 

estimate of -307.9 MMCF (tables B21–B24). A negative estimate of net growth in 

Wyoming signifies an inventory of live trees that is decreasing annually in the absence of trees removed from human-caused activities. High levels of tree mortality 

are offsetting gains in live tree growth. The Forest Service ownership group had 

the largest negative estimate of net growth, -309.6 MMCF, whereas undifferentiated private was much lower -1.7 MMCF (table B21). The National Park Service 

had the largest net growth of any owner class at 9.1 MMCF (table B21), which 

likely reflects the relatively large acreage of young, postfire lodgepole pine stands 

in Yellowstone National Park (see the Fire in Wyoming’s Forests section below).

Gross growth and mortality for the eight species with the greatest total volume in Wyoming indicated that annual mortality exceeded growth for over half of 

the species (fig. 6). This resulted in negative net growth for most major softwood 

species in the State: lodgepole pine, Engelmann spruce, whitebark pine, Douglasfir, and limber pine. Positive net growth occurred for subalpine fir and ponderosa 

pine (fig. 6).

High mortality rates over the last 5 years in Wyoming are the driving force 

behind the large differences between gross and net growth and warrants further 

examination. Converting the State-level estimates of mortality into per-acre estimates removes the effect of differences in the amount of forest land administered 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 21

-3.0% 

-2.0% 

-1.0% 

0.0% 

1.0% 

2.0% 

1984 periodic 2000 periodic 2011-2012 2011-2013 2011-2014 2011-2015 

Net growth as a percentage of total volume 

Annual 

Figure 5—Net growth of all live trees (>5 inches diameter) as a percentage of total live volume (>5 inches diameter) 

for the State of Wyoming for evaluation periods from 2011–2012 to current (2011–2015), including two previous periodic inventories. 

0 50 100 150 200 250 

ponderosa pine 

subalpine fir 

quaking aspen 

limber pine 

Douglas-fir 

whitebark pine 

Engelmann spruce 

lodgepole pine 

Million cubic feet 

Species 

Gross growth Mortality 

Figure 6—Annual gross growth and mortality on forest land for eight major species, Wyoming, 2011–2015. 

Net annual growth equals gross growth minus mortality. 
22 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

by different ownership groups. Across all ownerships, and reserve status, the 

Statewide per-acre estimate of annual mortality volume was 55.1 cubic feet per 

year on forest land (fig. 7). Average annual mortality on reserved land was 68.2 

cubic feet per acre, compared to 49.1 cubic feet per acre, on average, on unreserved 

forest land across all ownerships (see Appendix A for definitions). Regardless of 

reserve status, national forest land in Wyoming exhibited higher per-acre estimates 

of mortality (fig. 7).

All trees classified as mortality trees are assigned a primary cause of death in 

the field. Drawing conclusions from mortality estimates by cause of death should 

be done with caution because the actual causal agent may be difficult to interpret. 

Interactions between insects and diseases are complex and can make identification 

of proximate causes of mortality difficult (see the Bark Beetle Infestation section). 

Mortality due to insects accounted for the vast majority in the State, while fire was 

the second leading contributor to mortality (fig. 8). The “Other” cause of death category includes trees that have died due to animals, weather, silviculture, or reasons 

the field crews were unable to determine. The differences in levels of tree mortality 

by reserved status found in Wyoming has also been observed in other State inventories (Goeking et al. 2014; Menlove et al. 2012; Witt et al. 2012). In Wyoming, 

nearly twice as much mortality volume attributable to insects occurred on land that 

is not reserved, whereas fire-caused mortality was almost twice as common on reserved land status (fig. 8). Interestingly, the volume of disease- and weather-caused 

mortality was nearly equal between reserved and not reserved land status (fig. 8).

0 

20 

40 

60 

80 

100 

120 

National Forest National Park 

Service 

Bureau of Land 

Management 

State Private 

Cubic feet per acre 

Ownership group 

Reserved Not reserved 

Figure 7—Average annual per-acre mortality on 

forest land by two major 

owner categories and 

reserved status, Wyoming, 

2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 23

Numbers of Trees

Estimates of the numbers of trees, when combined with information about 

the size and species, can be used to provide meaningful summaries of forest stand 

dynamics, structure, and composition. Young or dense forest stands usually consist 

of relatively large numbers of small-diameter trees, whereas older forest stands 

contain small numbers of large-diameter trees. FIA classifies individual tree species into species group and also categorizes each species and species group as 

either softwood or hardwood (Appendix D).

There are an estimated 4.6 billion live trees 1.0 inch in diameter or larger 

(table B10) on Wyoming’s forest land area. Softwoods species total 4.3 billion 

trees or 94 percent of the State’s live trees whereas hardwoods (mostly cottonwoods and quaking aspen) make up the remaining 6 percent. The most abundant 

species group is Lodgepole pine, which totaled 1.8 billion trees and accounted for 

39 percent of live trees in the State. An additional 25 percent of the trees (1.2 billion trees) fall within the True fir species group, which consists of subalpine fir in 

the State. As shown in table B10, the third most abundant species group was the 

Engelmann and other spruces group, which totaled 4.5 million trees and accounted 

for over 9 percent of the total number of live trees. The trend in the three most 

predominant tree species groups was reflected in the growing stock trees (live trees 

greater than 5 inches in diameter) as well, with Lodgepole pine accounting for 32 

percent, followed by True fir (22 percent) and Engelmann and other spruces (13 

percent; table B11).

0 

50 

100 

150 

200 

250 

300 

Insect Disease Fire Weather Other 

Volume (million cubic feet) 

Cause of death 

Reserved Not reserved 

Figure 8—Average 

annual per-acre mortality on forest land 

by reserved status 

and cause of death, 

Wyoming, 2011–2015. 
24 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

The distribution of live trees by diameter class revealed a typical inverse 

j-shape for all trees in Wyoming (fig. 9). The distribution of individual species 

groups across diameter classes reflects their life history traits (e.g., relative shade 

tolerance, seed storage, dispersal strategy). For example, lodgepole pine is known 

to regenerate prolifically after large-scale fires such that densities exceed many 

thousands per acre. Similarly, subalpine fir is very tolerant of low light conditions 

and commonly perpetuates itself in the understory of spruce-fir and lodgepole pine 

forests. Conversely, the distribution of two important commercial timber species, 

Douglas-fir and ponderosa pine, is much flatter across diameters reflecting lower 

tolerance to low light conditions and individual longevity.

Live and Dead Tree Volume and Biomass

The quantity of wood volume in trees can be important for determining stocking and the sustainability of current and future wood utilization. The forest products industry and forest managers can use assessments of tree species composition, 

size distribution, and wood volume, as well as the geographic location and ownership status of land parcels to plan for harvest activities. Additionally, estimates 

of volume and biomass are becoming increasingly important for assessments of 

wildlife habitat and other societal values such as carbon accounting. Estimates 

of gross and net volume include only the merchantable portion or sawlog portion (e.g., cubic-foot or board-foot) of live trees 5.0 inches in diameter and larger. 

Net volumes are computed by deducting rotten, missing, or form defects from 

0 

200 

400 

600 

800 

1,000 

1,200 

1.0-2.9 3.0-4.9 5.0-6.9 7.0-8.9 9.0-10.9 11.0-12.9 13.0-14.9 15.0-16.9 17.0+ 

Number of trees (millions) 

Diameter class (inches) 

Lodgepole pine 

True fir 

Engelmann and other spruces 

Other western softwoods 

Cottonwood and aspen 

Ponderosa and Jeffrey pine 

Douglas-fir 

Western woodland softwoods 

Other western hardwoods 

Western woodland hardwoods 

Figure 9—Number of live trees on forest land, by diameter class and species group, Wyoming, 2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 25

gross volume. Net volume is reported below as net volume of all live trees, net 

volume of growing-stock trees, net volume of sawtimber, and net volume of sawlogs (Appendix A). Biomass estimates are based on gross volumes and describe 

aboveground tree weight (oven-dry) by various components (merchantable bole 

and bark, tops and limbs, saplings) (Appendix E).

The net volume of all live trees on Wyoming’s forest land totals 14.5 billion 

cubic feet (table B12). Almost 65 percent, or 9.4 billion cubic feet, is located on 

lands administered by the NFS. About 21.2 percent of the live volume on NFS 

lands exists on reserved lands and is unavailable for harvest (table B12). The vast 

majority of the net volume on NFS ownership is composed of lodgepole pine, 

Engelmann spruce, subalpine fir, and Douglas-fir (table B14). Forest land controlled by the National Park Service accounts for 19.7 percent of total live volume, 

or 2.9 billion cubic feet (table B12), which occurs entirely in reserved forest status 

and is dominated by lodgepole pine (55 percent, table B14). Privately owned forests contain 8.4 percent of the State’s total live volume, or 1.2 billion cubic feet 

(table B12), which is predominately ponderosa pine (table B14).

The Lodgepole pine species group has the highest amount of live tree volume, at 4.6 billion cubic feet (32 percent of the total), of any species group. Second 

in abundance, the Engelmann and other spruces species group accounts for 21 

percent, or 3.1 billion cubic feet. Third in abundance, the True fir species group 

accounts for 17 percent, or 2.5 billion cubic feet. Douglas-fir and Ponderosa pine 

species groups follow with 10 percent and 8 percent, respectively (table B14, 

fig. 10). The net volume of growing-stock trees on timberland in Wyoming totals 

8.7 billion cubic feet (table B17), or 60 percent of the total live volume on forest 

land. Growing-stock trees are live, merchantable trees that occur on timberland 

and represent timber that is potentially available for harvest. The availability of 

timber volume for harvest is affected by three primary factors: reserved status, 

productivity, and merchantability (see Appendix A for definitions).

Live volume is also reported for sawtimber trees, which are defined as softwood trees 9.0 inches in diameter or larger, or hardwood trees 11.0 inches in diameter or larger (International 1⁄4-inch rule). The net volume of sawtimber trees on 

timberland totals 33.6 billion board feet, with most of that volume existing in the 

Engelmann and other spruces and the True fir species groups (table B19).

The pattern of standing dead stocking varied from live tree stocking across 

species groups (fig.10). The ratio of standing dead tree to live tree stocking was 

highest for the Other western softwoods species group, which had a substantially 

higher ratio than any other group. The high levels of standing dead in this group 

were driven by relatively recent mortality of the whitebark pine component (see 

the Whitebark Pine Status and Trends section below). All other species groups had 

less standing dead trees than live trees, but the ratio varied from 66 percent for the 

Lodgepole pine species group, to nearly half (49 percent) for Douglas-fir, and only 

7 percent for the Ponderosa and Jeffrey pine species group (fig. 10). See the Snags 

as Wildlife Habitat section below for an in-depth analysis of standing dead trees 

in Wyoming.
26 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

The relationship between the growing stock volume on timberland and all 

live volume on all forest land by species group indicates possible species available 

for timber harvest in Wyoming. Over 93 percent, or 1.1 billion cubic feet, of the 

total live volume in the Ponderosa and Jeffrey pine species group is growing stock 

volume on timberland (fig. 10). The Cottonwood and aspen (79 percent), Douglasfir (77 percent), True fir (70 percent), and Engelmann and other spruces (60 percent) species groups also had relatively high ratios of growing-stock volume to 

live tree volume. The relatively low ratio of the Lodgepole pine species group (46 

percent), the most common tree in the State by number of trees (fig. 9), indicates a 

large portion of this species type group occurs in younger, small-diameter stands.

Biomass is typically sold by green weight; however, the water content of 

wood is highly variable geographically, seasonally, and even across portions of a 

single tree. Therefore, live tree inventory estimates of green biomass may be unreliable or even misleading. In contrast, oven-dry weight does not change due to 

fluctuations in tree water content. The total weight of oven-dry aboveground biomass on Wyoming’s forest land is 255 million dry short tons, and approximately 61 

percent (155 million dry short tons) occurs on timberland (table B29). Forty-eight 

percent, or 122 million dry short tons, occurs on NFS timberland.

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

1-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180 181-200 201+ 

Percent distribution 

Stand age-class (years) 

Figure 10—Net cubic-foot volume of trees 5.0 inches in diameter or larger on forest land, cubic-foot volume of 

growing-stock trees on timberland, and cubic-foot volume of standing dead trees on forest land, by species group, 

Wyoming, 2011–2015. Note: Ponderosa pine is the only species in Wyoming in the Ponderosa and Jeffrey pine species group. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 27

The highest per-acre estimate of biomass occurs in the Douglas-fir foresttype group, followed by Fir/spruce/mountain hemlock, and Lodgepole pine (table 4). Highest per-acre estimates of volume occurred in the Fir/spruce/mountain 

hemlock forest-type group at 2,116 cubic feet per acre, followed by Douglas-fir. 

The four highest per-acre estimates of volume and biomass occurred in timber 

types. Aspen/birch, Other western softwoods, and the Pinyon/juniper forest-type 

groups had much lower estimates per acre (table 4).

Stand Age

The age structure of forest land provides insight into shifts in stand structure, 

composition, and succession. On every FIA plot that samples forest land, and includes suitable trees for increment core extraction, stand age is estimated based 

on the average age of only those trees that fall within the calculated size-class category. For example, if an FIA plot occurred in a softwood forest type where about 

30 percent of the live trees were in the large-diameter size-class (trees at least 9.0 

inches in diameter and larger), and 70 percent were in the medium diameter sizeclass (trees between 5.0 and 9.0 inches in diameter), the stand would be classified 

as a medium diameter stand size class, and therefore only the medium-size trees 

would be used in determining stand age.

The age-class distribution of forest land in Wyoming is strongly centered 

around the 81–120 year age classes, with a notable peak of very young stands (1–

20 years), and a less notable peak of very old (201+ years) stands (fig. 11). Thirtyseven percent of Wyoming’s forest land, or 3.8 million acres, are between 81 and 

140 years of age, likely reflecting a combination of settlement-era harvesting and 

species longevity. Young stands represent the single largest 20-year age class and 

comprise about 1.7 million acres of Wyoming’s forest land. Another 8 percent, or 

just under 1 million acres of Wyoming’s forest land, are in stands over 201 years 

of age. Twenty percent of the 201+ age class is in the Pinyon/juniper forest-type 

group, the only group with the largest percentage of stands in the oldest age class.

Table 4—Net volume (cubic feet per acre) of live trees 5.0 inches diameter and larger, and biomass (tons 

per acre) of live trees 1.0 inches diameter and larger, averaged by common forest types, Wyoming, 

2011–2015. Because estimates obtained for forest-type groups with a small number of plots have high 

standard errors, only forest types with greater than 20 plots are included.

Forest-type group Number of plots

Net volume (cubic 

feet per acre)

Biomass (tons 

per acre) 

Douglas-fir group 75 1831 35.7

Fir / spruce / mountain hemlock group 264 2116 33.9

Lodgepole pine group 215 1693 30.5

Ponderosa pine group 81 1292 24.0

Aspen / birch group 60 802 15.9

Other western softwoods group 53 563 10.6

Pinyon / juniper group 103 429 8.2

Nonstocked 41 53 1.0
28 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Considerable differences are apparent in stand-age distribution among the 

major forest-type groups in the State (fig. 12). The Pinyon/juniper and Elm/ash/

cottonwood forest-type groups have the most even distribution of forest area across 

all age-class groups, whereas the Aspen/birch and the Ponderosa pine forest-type 

groups have strong unimodal distributions. Furthermore, the Aspen/birch group 

has two peaks, one in the 1–20 year age class, which is the single largest 20-year 

age class, and one in the 81–100 year class. The Ponderosa pine forest-type group 

exhibited a substantial peak in the 81–120 year age classes. This peak represents 

60 percent of the forest-type group across the State. The Douglas-fir, Fir/spruce/

hemlock, and Lodgepole pine forest-type groups also exhibit a characteristic peak 

in the 81–120 year age classes, but include stands more evenly distributed across 

all age classes. These groups also have peaks in the 1–20 year age class, presumably a result of fires and insect infestation over the past few decades.

Stand Density Index

Stand density index (SDI; Reineke 1933) is a relative measure of stand density, based on quadratic mean diameter of the stand and the number of trees per 

acre. In the western States, silviculturists often use SDI as one measure of stand 

structure to meet diverse objectives such as ecological restoration and wildlife 

habitat (e.g., Lilieholm et al. 1994; Long and Shaw 2005; Shaw and Long 2007; 

Smith and Long 1987). Originally developed for even-aged stands, SDI can also be 

0 

0.02 

0.04 

0.06 

0.08 

0.1 

0.12 

0.14 

0.16 

0.18 

1-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180 181-200 201+ 

Percent distribution 

Stand age-class (years) 

Figure 11—Stand-age class distribution of forest land in Wyoming, 2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 29

applied to uneven-aged stands (Long and Daniel 1990; Shaw 2000). Stand structure can influence the computation of SDI, so the definition of maximum SDI must 

be compatible with the computation method. SDI was computed for each condition 

that sampled forest land using the summation method (Shaw 2000), and the SDI 

percentage was calculated using the maximum SDI for the forest type found on the 

condition.

Maximum SDI is rarely, if ever, observed in nature at the stand-scale because 

the onset of competition-induced (self-thinning) mortality occurs at about 60 percent of the maximum SDI (Long and Smith 1984). Within-stand variability of density results in the average stand density being well below that of the densest patches. A site is considered to be fully occupied at 35 percent of maximum SDI (Long 

1985). Below about 25 percent of maximum SDI, individual trees are considered 

“free to grow.” At these lower densities, individual tree growth is maximized but 

stand growth is below potential, while at higher densities, individual tree growth 

is below potential, but stand growth is maximized (Long 1985). There are several 

reasons why stands may have low SDI. For example, low SDI is typical following 

major disturbances, such as fire, insect attack, or harvesting. These stands remain 

in a low-density condition until regeneration fills available growing space. Stands 

that are over-mature can also have low SDI, because growing space may not be reoccupied as fast as it is released by the mortality of large, old trees. Finally, stands 

that occur on very thin soils or rocky sites may remain at low density indefinitely, 

because limitations on physical growing space do not permit full site occupancy.

0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

1-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180 181-200 201+ 

Percent distribution 

Stand age-class (years) 

Pinyon/juniper group 

Douglas-fir group 

Ponderosa pine group 

Fir/spruce/mountain hemlock group 

Lodgepole pine group 

Other western softwoods group 

Elm/ash/cottonwood group 

Aspen/birch group 

Figure 12—Stand-age class distribution by major forest-type groups for Wyoming, 2011–2015. 
30 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Because the periodic inventory of Wyoming used the annualized plot design, 

and most of the plot locations were carried over to annual inventory, it is possible to look at changes in stand density over this time period. For this analysis, 

conditions measured during the 2000 periodic inventory (measured 1998–2002) 

are compared to conditions measured during the first half of the inventory cycle 

(2011–2015). Each condition-level SDI value was binned at 20-unit intervals, and 

then the number of conditions in each bin was normalized to account for the differing numbers of observations in each inventory. After normalization, values from 

the two periods can be plotted together in each bin for direct comparison (fig. 13).

The distribution of SDI values in Wyoming is generally more even across 

density classes than in other Interior West States, probably due to the predominance of forest types that normally occur as high-density stands (e.g., Lodgepole 

pine). Comparison of SDI means and distributions (fig. 13) suggests that there had 

been an overall lowering of stand density since the early 2000s. Mean SDI was 

197.3 for conditions measured during the periodic inventory and 160.3 for conditions measured during the annual inventory (significantly different, P < 0.01). 

During the periodic inventory just over 51 percent of conditions had a SDI of 200 

or lower, whereas during annual inventory the proportion of conditions in this density range is over 68 percent. In the middle density classes (SDI greater than 200 

and up to 300), the proportions of conditions are nearly identical for both inventory periods, at just over 21 percent. The number of conditions with SDI greater 

0.0% 

1.0% 

2.0% 

3.0% 

4.0% 

5.0% 

6.0% 

7.0% 

8.0% 

20 40 60 80 

100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 

600+ 

Proportion of conditions 

Stand density index class 

2000 Periodic inventory (mean = 197.3) 

2015 Annual inventory (Mean = 160.3) 

Figure 13—Distribution and average of stand density index (SDI) for the 2000 periodic inventory and first half 

cycle (2011–2015) of annual inventory in Wyoming. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 31

than 300 in the annual inventory is about half of what it was during the periodic 

inventory, falling from 21 to 10 percent. This shift is among the largest observed 

in Interior West States.

The overall reduction of stand density is consistent with other results of the 

inventory. Many species have experienced a period of negative net growth (tables 

B21–B24, fig. 6), which means that mortality is freeing up growing space faster 

than the surviving trees on a site can re-occupy that space. While disturbances 

such as insects, fire, and drought have substantially reduced the overall density of 

Wyoming’s forests, these changes have opened growing space for new regeneration. Although the impacts to the current, aging forest are widespread and relatively severe, the younger, incoming cohorts of trees will be more resistant in the 

next few decades to many of the stressors (i.e., bark beetles) that contributed to 

mortality in older stands.

Periodic to Annual Inventory Comparisons

One purpose of Wyoming’s annual forest inventory is to provide information 

about changes in forest attributes over time. If the definitions and methods used 

during the periodic inventories were compatible with those used during the annual 

inventory, we could quantify trends over the past 30 years. However, the sampling 

and field procedures used during the periodic inventories were different enough 

from those of the annual inventory to preclude reliable trend analysis, and doing 

so may produce misleading results (Goeking 2015). This section describes the primary differences between the periodic and annual inventories. It also presents an 

appropriate method for comparing periodic and annual inventory data from plots 

that were measured during both inventories, or co-located plots. Using co-located 

plots some changes in forest attributes are summarized. 

The primary differences between Wyoming’s periodic and annual forest inventories pertain to the plot configuration, sample design, and operational definitions used during field data collection. The periodic inventory of 1983 used a 

variable-radius plot configuration with five subplots. In contrast, the plot configuration of the periodic inventory of 1998–2002, as well as the current annual inventory, consists of four fixed-radius subplots, as described in the Inventory Methods

section of this report. Sample designs also changed appreciably, from samples that 

omitted national forest lands and targeted high-productivity stands in 1983, to a 

spatially representative plot grid with consistent sample intensity across all forest types and management categories in the annual inventory. Wyoming’s 1983 

inventory also used an operational definition of “tree” that differentiated between 

tree-form and shrub-form trees. For example, junipers that were less than 6 feet 

tall and were not expected to eventually produce a straight, 8-foot trunk section 

were not considered to be trees and were not measured, so they were not included 

in volume-based estimates such as biomass, growth, and mortality. In contrast, 

the annual inventory identifies trees strictly by their species, regardless of growth 

form. Therefore, trees on many woodland plots in the current annual inventory 

would not have been measured under previous definitions.
32 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Due to these differences in forest inventories over time, users of FIA data 

should be aware of appropriate methods for evaluating trends and avoid inappropriate methods. Examples of inappropriate comparisons between periodic and annual inventories range from comparing the tree volume on a specific forest type to 

directly comparing the total area of forest land. Instead, an appropriate method of 

quantifying trends is to first identify forest plots that were measured during both 

periodic and annual inventories, and then assess trends at only those plots. FIA 

refers to such plot locations as co-located plots, which represent a subset of the 

annual inventory plots that were established at the same locations as a subset of 

periodic inventory plots in order to allow for temporal comparisons. Although this 

type of analysis can be complicated when different plot designs were used during 

the periodic and annual measurements of co-located plots, each plot design allows 

estimation of volume, growth, and mortality per acre. Therefore comparisons of 

multiple measurements at co-located plots are useful for quantifying trends in attributes on a per-acre basis.

Wyoming Forest Attribute Change

This section presents the results of two analyses of co-located plot data collected during periodic versus annual inventories in Wyoming. The first analysis 

compares data collected from co-located plots that were measured once between 

1998 and 2002 and again after 2011. The second analysis compares a smaller sample of co-located plots that were measured three times: first in 1983, second during 

1998–2002, and third during 2011–2015. The geographic distribution of all plots 

in the 1983 inventory, all plots in the 1998–2002 inventory, all plots in the annual inventory (2011–2015), and the co-located plots from the two analyses varied 

widely (fig. 14).

The comparison of plot measurements between 1998–2002 and 2011–2015 

consisted of 803 co-located plots that were measured during both inventories. 

During this time period, mean total net volume decreased, live net volume decreased, and dead net volume increased (fig. 15). Mean annual mortality increased 

from 14 to 58 cubic feet per acre per year, and mean annual net growth decreased 

from 19 to -32 cubic feet per acre per year (fig. 16). A paired t-test showed that all 

of these changes were statistically significant (P < 0.001). The magnitude of the 

change in net growth is greater than the magnitude of the change in mortality (because net growth = gross growth – mortality). Therefore, the change in net growth 

reflects a large increase in mortality accompanied by a decrease in gross growth.

The second analysis consisted of 152 co-located plots that were measured 

three times: in 1983, during the 1998–2002 inventory, and during the annual inventory (2011–2015). The results show the same patterns as those from the first 

comparison for the period 1998–2002 to 2011–2015 comparison: a decrease in live 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 33

Figure 14—Approximate locations of periodic inventory forest plots measured in 1983, some of which were remeasured during 

1998–2002 and 2011–2015 (A); periodic inventory forest plots measured during 1998–2002, some of which were remeasured during 

2011–2015 (B); and all annual inventory forest plots measured in 2011–2015 (C). Plot locations are approximate. 
34 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

0 

500 

1000 

1500 

2000 

2500 

3000 

Live net volume Dead net volume Total volume 

Cubic feet per acre 

Co-located plots 

1998-2002 2011-2015 

-50 

-25 

0 

25 

50 

75 

Mortality Net growth 

Cubic feet per acre per year 

Co-located plots 

1998-2002 2011-2015 

Figure 15—Live net volume, 

dead net volume, and total net 

volume, in cubic feet per acre, 

at 803 plots measured during 

1998–2002 and remeasured during 2011–2015. 

Figure 16—Mean annual mortality and net growth, in cubic feet 

per acre per year, at 803 plots 

measured during 1998–2002 and 

remeasured during 2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 35

and total volume, and an increase in dead volume (fig. 17). However, because this 

analysis included only plots that were measured in 1983 as well as the two more 

recent inventories, it provides a longer-term historical context for these changes. 

Compared to 1983 conditions, total volume and dead volume in 2011–2015 have 

increased. Live net volume per acre increased in the late 1990s/early 2000s, but 

current live volume is approximately at the same level as it was in 1983 (fig. 17).

To investigate changes for individual tree species, we quantified live basal 

area, dead basal area, mean annual growth, and mean annual mortality, as measured at co-located plots in 1998–2002 and again in 2011–2015, for the seven 

species that have the highest abundance and volume in Wyoming. In descending 

order of live volume, these are: lodgepole pine, Engelmann spruce, subalpine fir, 

Douglas-fir, ponderosa pine, whitebark pine, and quaking aspen. In 2011–2015, all 

major species except ponderosa pine had lower live basal area per acre, and more 

dead basal area per acre, than in 1998–2002 (fig. 18), which is consistent with the 

results of the Forest Growth, Mortality, and Removals section (above). Similarly, 

all major species except for ponderosa pine showed increases in mean annual 

mortality and decreases in mean annual net growth (fig. 19). By comparing the 

magnitudes of change in mortality and net growth, we can determine whether the 

decreases in net growth are entirely due to increases in mortality, or in other words, 

whether gross growth has changed. Based on the magnitudes of these changes, 

all seven species have experienced decreases in gross growth with concomitant 

increases in mortality (figs. 18 and 19).

These results are consistent with a previous analysis based on only 2 years’ 

worth of annual inventory data from Wyoming, which found a decrease in live 

0 

200 

400 

600 

800 

1000 

1200 

1400 

Live net volume Dead net volume Total volume 

Cubic feet per acre 

Co-located plots 

1983 1998-2002 2011-2015 

Figure 17—Live net volume, 

dead net volume, and total net 

volume, in cubic feet per acre, 

at 152 plots measured three 

times: 1983, 1998–2002, and 

2011–2015. 
36 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

net volume, increase in dead net volume, an increase in mortality, and decrease in 

net growth (Goeking 2015). The caveat of the co-located plot analysis presented 

here is that results cannot be scaled to the entire State and cannot overcome the 

limitations of the periodic sample design. For example, if the periodic inventory 

under-sampled a particular forest type, an analysis of co-located plots will still 

under-represent that forest type. As mentioned above, the 1983 inventory omitted 

reserved lands and national forest lands. Therefore, the results of the second analysis reflect long-term trends that may be related to land management practices or 

geographic factors associated with the different land ownership groups that were 

targeted during the first periodic inventories. Nonetheless, these results provide an 

indication of the direction of change in Wyoming’s forests. As Wyoming’s annual 

forest inventory continues and plots are remeasured at a consistent 10-year interval, FIA’s ability to quantify trends in forest attributes will expand from analyses 

of co-located periodic plots to robust Statewide estimates of change based on the 

spatially representative annual plot design.

0 

10 

20 

30 

40 

50 

60 

70 

t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 

lodgepole pine Engelmann 

spruce 

subalpine fir Douglas-fir ponderosa pine whitebark pine quaking aspen 

Basal area (ft2/acre) 

Species 

Live trees Dead trees 

Figure 18—Mean basal area for seven major tree species of Wyoming, as measured at co-located plots that were 

measured during the 1998–2002 inventory (t1) and again between 2011 and 2015 (t2). The number of plots varied by 

species.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 37

Wyoming’s Forest Resources

Removals for Timber Products

Volume removed from forest inventory during the harvesting of timber is referred to as removals. Removals are an important indicator of the sustainability 

of timber harvest levels. Removals exceeding net growth over an extended period 

could indicate over-harvesting and decreasing forest inventory. Conversely, growth 

or mortality greatly exceeding removals could signal a need for increased vegetation management to decrease risks from tree mortality, insect outbreaks, or wildfire.

Removals can come from two sources: growing-stock (portions of live, commercial tree species meeting specified quality or vigor standards), or dead trees 

and other non-growing stock sources (e.g., tree limbs and tops). The two general 

types of removals are timber products and logging residue (i.e., volume cut or dead 

but not utilized). Removals, as reported here, are based on a survey of Wyoming’s 

primary forest products industry’s 2014 operations (McIver et al., in review) and 

the U.S. Energy Information Administration data for residential fuelwood consumption (EIA 2016). More detailed timber products and logging residue data for 

Wyoming and other States are available from FIA’s Timber Products Output (TPO) 

website: https://www.fs.usda.gov/srsfia/php/tpo_2009/tpo_rpa_int1.php. 

-50 

-40 

-30 

-20 

-10 

0 

10 

20 

30 

40 

50 

t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 t1 t2 

lodgepole pine Engelmann 

spruce 

subalpine fir Douglas-fir ponderosa pine whitebark pine quaking aspen 

Mortality and net growth (feet3/acre/year) 

Species 

Mortality Net growth 

Figure 19—Mean annual mortality and net growth, in cubic feet per acre per year, for seven major tree species in 

Wyoming, as measured during the 1998–2002 inventory (t1) and again between 2011 and 2015 (t2). The number 

of plots varied by species. 
38 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Total removals in Wyoming during 2014 were nearly 25 million cubic feet 

(MMCF). Total removals included 20.8 MMCF of timber products, including industrial and residential fuelwood, and 4.1 MMCF of logging residue left in the 

forest (table 5). Growing-stock sources accounted for approximately 13 MMCF of 

total removals. A relatively small amount of growing-stock volume (0.7 MMCF) 

was unutilized and left in the forest as logging residue, with approximately 95 

percent of growing-stock removals used to produce wood products. Nearly 98 

percent of growing-stock removals in Wyoming came from softwood tree species. Ponderosa pine was the predominant species, accounting for approximately 

41 percent (5.3 MMCF) of growing-stock removals, followed by lodgepole pine 

representing 36 percent (4.7 MMCF). Engelmann spruce and Douglas-fir each accounted for approximately 11 percent (1.5 MMCF and 1.4 MMCF, respectively) 

of growing-stock removals.

The Statewide growing-stock removals for timber products and logging residue in 2014 represent about 8 percent of the average annual gross growth (172 

MMCF) and 4 percent of average annual mortality (328 MMCF) between 2011 

and 2015. The relationships between removals, growth, and mortality vary substantially by land ownership. Growing-stock removals on private lands account 

for about 21 percent of the annual gross growth and 24 percent mortality, whereas 

removals on national forest timberlands account for just 8 percent of gross growth 

and only 2 percent of annual mortality (table 6). The total volume of growing-stock 

trees on Wyoming timberland is about 8.73 billion cubic feet, so annual removals 

represent approximately 0.15 percent of growing stock1.

Table 5—Volume of removals by source of material, species group, and removal type, Wyoming, 2014. 

Source of material

Growing stock Other sources All sources

Removal type Softwoods

Hardwoods Total SoftwoodsHardwoods Total SoftwoodsHardwoods Total

---------Thousand cubic feet---------

Industrial Products

Saw logs 11,404 32 11,436 2,394 1 2,395 13,798 33 13,831

Industrial fuelwood 2 0 2 451 1 451 453 1 454

Posts and poles 627 0 627 421 0 421 1,048 0 1,048

Miscellaneous products 234 4 238 79 0 79 313 4 317

Total industrial products 12,267 36 12,303 3,345 2 3,346 15,612 38 15,650

Residential fuelwooda - - - - - 5,200 - - 5,200

Total all products 12,267 36 12,303 3,345 2 8,546 15,612 38 20,850

Logging residue 677 2 679 3,378 7 3,385 4,055 9 4,064

a Residential fuelwood consumption reported by the U.S. Energy Administration (EIA) http://www.eia.gov/state/seds/seds-data-compete.crm?sid=US#Consumption

1 The proportion of annual removals of the total growing-stock volume is roughly equivalent to a 670-year rotation, if all harvests 

were performed under even-aged management.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 39

In 2014, removals for all timber products (including industrial and residential 

fuelwood) totaled 20.8 MMCF, accounting for 84 percent of the total removals for 

the year (table 7). The remaining volume was comprised of logging residue, 83 

percent of which came from non-growing stock material. Of the 15.6 MMCF of 

removals for commercial products, approximately 88 percent were sawlogs (for 

producing lumber), making it the leading timber product in 2014. Posts and small 

poles accounted for 1.0 MMCF (almost 7 percent) of commercial product removals. Logs for miscellaneous wood products accounted for approximately 2 percent, 

with logs for industrial fuelwood accounting for the remaining 3 percent of commercial product removals. Nearly all (99.8 percent) of removals for commercial 

wood products consisted of softwood species.

Across Wyoming’s nearly 6 million acres of unreserved timberland, 67.5 million board feet (MMBF) Scribner, or about 15.6 MMCF, of commercial timber products (excluding residential fuelwood) were harvested in 2014. The volume of commercial timber products for 2014 is roughly 62 percent higher than the 2010 harvest 

and 5 percent higher than in 2005 (McIver et al. 2014). National forests supplied 

52 percent of the 2014 harvest while private and tribal lands supplied 34 percent. 

State lands provided the majority of the remaining harvest accounting for 12 percent, 

while the Bureau of Land Management supplied 1.6 percent of the volume (table 8).

The geographic sources of Wyoming’s timber harvest can be divided into 

five resource areas: northeast, north central, northwest, southeast, and southwest 

(fig. 20). The Southeast Resource Area experienced the largest shift, increasing 

from only 9.5 percent of the harvest in 2010 to 34.7 percent of the harvest in 2014. 

The North Central Resource Area experienced a slight decline in its proportionate harvest from 14.4 percent in 2010 to 12.7 percent, while the volume nearly 

doubled to 8.6 MMBF Scribner in 2014. The Northwest and Southwest resource 

areas experienced declines in their proportions as well as their actual volumes. 

The Northwest Resource Area harvested only 5.8 MMBF in 2014 compared to 

6.4 MMBF in 2010, while the Southwest declined from 7.4 MMBF to 5.9 MMBF.

Table 6—Average annual growth and mortality from 2011–2015 and 2014 timber removals, by 

ownership, for Wyoming growing-stock trees. 

Total

National 

Forest

Other 

public Private

2011–2015: Growing-stock trees ----------million cubic feet---------

Gross growth (MMCF) 171.64 136.96 14.12 20.56

Mortality 328.11 290.42 20.11 17.58

Net growth -156.47 -153.46 -5.98 2.97

2014: TPO removals 12.98 7.04 1.70 4.24

Products 12.30 6.68 1.61 4.02

Logging residue 0.68 0.37 0.09 0.22

Removals as % of gross growth 8% 5% 12% 21%

Removals as % of mortality 4% 2% 8% 24%
40 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Table 7—Total roundwood output by product, species group, and source of material, Wyoming, 2014. 

Source of material

Growing-stock trees

Products and species group Sawtimber Poletimber Other sources All sources

---------Thousand cubic feet---------

Sawlogs

 Softwood 10,083 1,321 2,394 13,798

 Hardwood 28 4 1 33

 Total 10,111 1,325 2,395 13,831

Industrial fuelwood

 Softwood 2 0 451 453

 Hardwood 0 0 1 1

 Total 2 0 451 454

Posts and poles

 Softwood 63 564 421 1,048

 Hardwood 0 0 0 0

 Total 63 564 421 1,048

Other miscellaneous

 Softwood 207 27 79 313

 Hardwood 4 1 0 4

 Total 211 28 79 317

Total industrial products

 Softwood 10,354 1,913 3,345 15,612

 Hardwood 32 4 2 38

 Total 10,387 1,917 3,346 15,650

Residential fuelwooda 5,200 5,200

All products 10,387 1,917 8,546 20,850

a Represents residential fuelwood consumption as reported by U.S. Energy Information Administration (EIA) http://www.eia.gov/state/

seds/seds-data-complete.cfm?sid=US#Consumption.

Table 8—Wyoming timber harvest volume by ownership source and product type, 2014. 

Ownership source Saw logs Post and pole Fuelwooda

Other 

productsb All products

-----------------------Thousand cubic feet---------------------

 Nonindustrial and tribal 4,742 450 68 53 5,313

 National forests 7,169 470 339 258 8,237

 Other Federal and public 1,919 127 47 6 2,100

Total 13,831 1,048 454 317 15,650

a Fuelwood does not include residential firewood as reported by EIA (2016).

b Other products include house logs, log furniture and biomass. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 41

The other region that experienced a significant increase in its timber harvest 

was the Northeast. The resource area’s proportion of the State timber harvest remained relatively stable at 35 percent; however the volume of timber harvested 

more than doubled to 23.8 MMBF in 2014. Overall, the geographic source of 

timber in 2014 shifted away from the western half of the State and was heavily 

concentrated in the eastern half, where the majority of milling infrastructure and 

capacity resides.

Figure 20—Wyoming’s resource areas and active primary manufacturers, 2014. 
42 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Wyoming’s Timber Industry

The 2014 census, conducted by the Bureau of Business and Economic 

Research at the University of Montana, identified 28 active primary forest products manufacturers in Wyoming (fig. 20). These facilities produced an array of 

products from timber including lumber and other sawn products, wood pellets, 

house logs, posts, poles and rails, firewood, log furniture, and animal bedding. 

Total sales of finished products exceeded $62.4 million in 2014, a 100 percent 

(inflation-adjusted) increase from 2010.

While the total number of mills was one fewer than reported in the 2010 

census (McIver et al. 2014), the industry experienced a significant increase in 

its capacity to process timber. Most of the additional capacity was added in the 

Southeast Resource Area, where two inactive sawmills had restarted. The post and 

pole sector also added one new and one reactivated facility in southeast Wyoming. 

Net losses in the number of mills occurred primarily in the house log, firewood and 

fuel pellet sectors. Geographically, many of the mills that were closed or inactive 

during 2014 were located in the northern half of the State. Park County, which contained the most (13) facilities in 2005 (McIver et al. 2014), had no active facilities 

in 2014. The Northwest Resource Area had a decline from a high of 28 facilities 

operating in 2000, to just seven in 2014 (fig. 20).

In contrast to the volume of timber harvested in the State, timber receipts 

refer to the volume of timber delivered to Wyoming mills from in-State and outof-State sources. In 2014, Wyoming mills received 91.4 MMBF Scribner of timber 

for processing. Over half (49.3 MMBF) of the timber processed in Wyoming came 

from outside the State. Wyoming mills relied heavily on out-of-State timber from 

public lands in 2014, of which 89 percent (43.9 MMBF) came from NFS lands in 

adjacent States. The distribution of Wyoming’s mills near the State’s borders with 

South Dakota, Colorado, and Montana contributed to the large proportion of outof-State timber being used in-State.

Wyoming timber processors produced almost 211,000 bone dry tons (BDT2) 

of mill residue in 2014, with 96 percent utilized. Fine wood residues (e.g., sawdust) accounted for nearly 41 percent of total mill residue (approximately 86,000 

BDTs), followed by coarse residues suitable for chipping (e.g., slabs, edging) at 35 

percent, and finally bark residues around 24 percent (51,000 BDTs).

Long-term sustainability of Wyoming’s timberlands depends on several 

inter-related factors such as active management of lands available for timber production, the presence of a forest products industry capable of processing harvested timber, and harvest levels that meet societal demands while fostering continual site productivity. To ensure sustainable forests and communities, careful 

consideration should be given not only to growth, removals, and mortality across 

Wyoming’s available timberlands, but also to the forest industry and employees 

who conduct management activities and utilize timber in Wyoming and surrounding States.

2 A bone dry ton (BDT) consists of 2,000 oven-dry pounds of wood.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 43

Canada Lynx Habitat

Some of Wyoming’s forested landscapes are home to a population of Canada 

lynx (Lynx canadensis), a reclusive forest carnivore that lives primarily in areas 

that accumulate and retain high amounts of snow. Lynx were listed as “threatened” 

under the Endangered Species Act in 2000 (USFWS 2000) and as such, resource 

managers are responsible for adopting management plans that protect lynx habitat 

in Wyoming. Primary lynx habitat includes areas that support high densities of 

snowshoe hares (Lepus americanus or “hare” hereafter), the lynx’s primary prey 

(Ruggiero et al. 2000). Snowshoe hares in Wyoming frequent both multi-storied 

spruce-fir forests with dense horizontal cover as well as young lodgepole pine 

stands with high stem densities (Berg et al. 2012). In Wyoming’s spruce-fir forests, 

stands having over 20 percent shrub cover (including small trees such as seedlings 

and saplings) and over 42 percent canopy cover have a higher likelihood of supporting populations of hares than forest land that does not meet these criteria (Berg 

et al. 2012). Lodgepole pine stands that support hares tend to have stem densities 

exceeding 1,130 stems per acre and horizontal cover greater than 60 percent at approximately 6.5 feet in height (Shaw 2002). Shaw (2002) also notes that horizontal 

cover targets are generally achieved in lodgepole pine stands that meet or exceed 

the stem density thresholds. These stands tend to be young enough (30–70 years 

old) that advanced self-pruning has not yet begun and low branches still provide 

hares with forage as well as thermal and security cover during winter months when 

snowpack is greatest. Similarly, shrub cover within thick stands of spruce-fir provide these important features as well.

FIA stand data were used to estimate the acreages of spruce-fir and lodgepole pine-dominated forests in Wyoming that meet the structural preferences of 

hares described above. For the Engelmann spruce, Blue spruce, Subalpine fir, and 

Engelmann spruce/subalpine fir forest types, acreages that had more than 42 percent canopy cover, and also shrub cover exceeding 20 percent, were estimated. 

For the Lodgepole pine forest type, the acreage in the 30–70 year age class that 

exceeded 1,130 stems per acre were estimated. These estimates provide an idea of 

how much potential snowshoe hare habitat exists in these forest types in Wyoming.

Figure 21 shows the proportion of acreage in each forest type that met canopy and shrub cover preferences. Across all of the forest types analyzed, 14 percent of the acreage met cover thresholds for canopy and understory shrubs. The 

Engelmann spruce/subalpine fir type had both the largest total amount of acreage 

that met the cover criteria (251,078 acres) and the largest proportion of its acreage 

(17.4 percent). Subalpine fir was next in both total and proportion of acreage meeting hare cover needs. Of the estimated 415,337 acres that have adequate canopy 

and shrub cover for hares, 272,295 acres (66 percent) occurred in the 101–200 year 

age class, with 130,158 acres (31 percent) occurring in the 0–100 year age class. 

Together, these two age classes had 97 percent of the acreage meeting structural 

preferences across the examined forest types. No potential habitat was indicated 

in the Blue spruce forest type, but with only about 12,000 acres estimated to be in 
44 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Wyoming, this forest type is fairly rare and should not be expected to contribute 

much in the way of habitat.

The area of the Lodgepole pine forest type with the potential to provide 

snowshoe hare habitat was restricted to a stem density criterion. FIA does not yet 

have a metric for horizontal cover, but an effort is being made to enable estimation 

of horizontal cover using standard FIA measurements. Stem density was calculated on a per-acre basis for all conditions classified as lodgepole pine by field crew 

observation, and area was calculated for all lodgepole pine stands with 1,130 or 

greater stems per acre. In addition, stand age was used to sum cumulative area by 

increasing stand-age class. This calculation was done for the 2000 periodic inventory and the current (2015) annual inventory (fig. 22).

In the 2000 inventory, only about 25,000 acres met the density threshold 

and were age 30 or younger. In the 2015 inventory, just over 250,000 acres met 

the same criteria. However, in both inventories relatively little additional area in 

stands aged 30 to 70 met the density threshold. Note: explanation for the large 

differences in estimates from the two inventories can be found in the Periodic to 

Annual Inventory Comparisons section.

Results from the comparison of inventories are consistent with the recovery 

of lodgepole pine forests following the fires of 1988 (see the Fire in Wyoming’s 

Forests section), which burned much of Yellowstone National Park and surrounding areas. The majority of forest area (about 70 percent) discussed below is located in Fremont, Park, and Teton counties, which were heavily affected by the 

0 

20 

40 

60 

80 

100 

120 

140 

160 

Engelmann spruce Engelmann spruce/ Subalpine fir Subalpine fir 

Acres (thousands) 

Forest type 

0-100 years 

101-200 years 

201-300 years 

Figure 21—Acres of spruce and fir forest types by stand age categories in Wyoming that meet canopy cover and shrub 

cover preferences for snowshoe hares, Wyoming, 2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 45

1988 fires. Figure 22 shows that in the 2000 inventory there was a relatively small 

amount of Lodgepole pine forest type that met the stand density criterion of 1,130 

trees per acre—less than 75,000 acres. About one-third of the area was in stands 

younger than 25 years old, which means that some portion of stands probably did 

not have sufficient height to provide the adequate foliage density snowshoe hares 

use for cover during the peak of winter snowpack. This is consistent with the timing of the 2000 inventory and the 1988 fires, because much of the regenerating 

lodgepole pine area was only 10 to 12 years old at the time of inventory. Stem 

density might have been sufficient to meet the criterion used here, but many of the 

stems were probably too small to be captured in the tree-size tally.

During the 2015 inventory, lodgepole pine stands that were 10 to 12 years 

old when sampled in the 2000 inventory were now 22 to 28 years old, or entering the prime phase of structure that could provide good snowshoe hare habitat 

(Shaw 2002). This is the result of increasing height and diameter growth, but the 

stands have not yet developed to such an extent that self-thinning has reduced stem 

density below the minimum considered to provide good snowshoe hare habitat. 

There are approximately 250,000 acres in this condition. The self-thinning effect 

is evident in the shape of the line for the 2015 inventory. While there are stands 

with greater than 1,130 trees per acres that are greater than 30 years old, these are 

0 

50 

100 

150 

200 

250 

300 

350 

0 10 20 30 40 50 60 70 

Acres (thousands) 

Stand age (years) 

2000 2015 

Figure 22—Cumulative area for stands meeting the density criterion of 1,130 trees per acre, ordered by stand age. 
46 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

likely so-called “dog-hair” stands, which are even-aged but slow-growing and have 

small mean diameter, or stands with complex structure, where age is determined 

by a relatively small number of residual trees and trees per acre is dominated by 

regeneration in the understory. In the case of older “dog-hair” stands, competition 

results in the bases of live crowns lifting with age, which in turn results in lower 

horizontal cover and less suitable snowshoe hare habitat. It is necessary to look at 

stands with more complex structure in detail to assess their potential value as hare 

habitat. However, comparison of stand age and structure from the two inventories 

shows that potentially valuable habitat conditions in lodgepole pine stands have 

become much more abundant since 2000.

The results presented here should be considered a liberal estimate of potential 

hare habitat in Wyoming. Habitat attributes such as spatial location, patch size, and 

connectivity are not considered in this analysis and are also important components 

of lynx and hare habitat. However, this analysis does provide resource managers 

with reliable estimates of forest land meeting structural preferences as well as a 

baseline for future monitoring of these habitats.

Whitebark Pine Status and Trends

Whitebark pine is an iconic, high-elevation conifer that occurs throughout 

the northern Rocky Mountains to the Pacific Coast. It has a mutualistic relationship 

with the Clark’s nutcracker (Nucifraga columbiana), which caches seeds in sites 

that can be favorable for establishment (Hutchins and Lanner 1982). Whitebark 

pine provides food for numerous other wildlife species including red squirrels and 

grizzly bears. Due to recent declines caused by a combination of factors, including 

mountain pine beetle (Dendroctonus ponderosae), changing fire regimes, white 

pine blister rust (Cronartium ribicola), (Keane et al. 2012; Raffa et al. 2008), the 

U.S. Fish and Wildlife Service considered protecting whitebark pine under the 

Endangered Species Act (USFWS 2011).

To illuminate broad-scale status and trends in whitebark pine populations in 

Wyoming, several attributes of whitebark pine were estimated Statewide and then 

compared among forest types and ownership groups. Attributes included forest 

land area with a whitebark pine component, size-class distribution of live and dead 

trees, mean annual growth, and mean annual mortality. Due to recent elevated 

levels of mortality for whitebark pine, the causal agents of mortality and damage 

to live trees were summarized as well. The estimates reported here were produced 

using the EVALIDatorPC tool, which is available from the FIA DataMart (USFS 

2016; Miles 2016). Note that EVALIDatorPC does not constrain estimates of forest land area to the presence of an individual tree species. To calculate ratio estimates of density attributes, such as trees per acre, we wrote custom queries within 

EVALIDatorPC that estimate the area of forest land with a whitebark pine component. Thus, the denominator in our ratio estimates was constrained to the area 

of forest land with a whitebark pine component rather than total forest land area. 

We defined the whitebark pine component as having at least one whitebark pine 

tree that meets at least one of the following conditions: live and at least 1.0 inch in 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 47

diameter, dead and at least 5.0 inches in diameter, or live and less than 1.0 inch in 

diameter but at least 6 inches tall (i.e., a seedling).

There were 222 FIA plots measured between 2011 and 2015 in Wyoming that 

had a whitebark pine component. Only 38 plots with a whitebark pine component 

were classified as Whitebark pine forest type; thus 184 plots were classified as a 

forest type other than Whitebark pine (fig. 23). The vast majority of plots with a 

whitebark pine component occurred on NFS lands (151 plots or 68 percent). Of 

the remaining 71 plots, 60 occurred on NPS lands (27 percent), 2 on BLM lands 

(about 1 percent), and 9 on private lands (about 4 percent). Because of the small 

sample size on BLM and private lands, the remainder of this analysis focused 

only on whitebark pine on NFS and NPS lands when land ownership group was 

considered.

The Whitebark pine forest type covers 397,000 acres in Wyoming, and forests with a whitebark pine component cover more than 2.4 million acres (table 9). 

However, the density of whitebark pine varies across this acreage. Therefore, the 

number and density of live and dead whitebark pine across all forest types and 

ownership groups were examined. Density was calculated as the number of trees 

in a particular category divided by the area of forest land with a whitebark pine 

component in that category (e.g., the number of whitebark pine in National Parks 

divided by the National Park area with a whitebark pine component). The mean 

density of whitebark pine seedlings (stems at least 6 inches tall but less than 1.0 

inch in diameter) is greatest in the Lodgepole pine forest type (fig. 24a). Density 

of all size classes larger than 1.0 inch in diameter is greatest within the Whitebark 

pine forest type (fig. 24b).

Lodgepole pine, 62, 

28% 

Engelmann spruce / 

subalpine fir, 54, 24% 

Whitebark pine, 38, 17% 

Subalpine fir, 26, 12% 

Engelmann spruce, 22, 

10% 

Nonstocked, 9, 4% 

Douglas-fir, 7, 3% Aspen, 4, 2% 

[CATEGORY NAME] 

<1% 

Figure 23—Percentage of 

222 plots with a whitebark 

pine component that occurred 

in each forest type, Wyoming, 

2011–2015. 
48 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Table 9. Area (acres) represented by plots with a whitebark pine component, by forest type and ownership group. Percent standard errors 

are shown in italics in parentheses. 

Ownership group

Forest type

National Forest 

System

National Park 

Service

Bureau of Land 

Management Private Total

Lodgepole pine 272,491 (19.9) 403,880 (16.4) 0 NA 23,842 (71.3) 700,213 (12.2)

Engelmann spruce / 

subalpine fir 500,490 (14.8) 104,537 (33.3) 0 NA 0 NA 605,026 (13.4)

Whitebark pine 282,962 (19.4) 72,186 (40.8) 0 NA 41,852 (50.5) 397,000 (16.3)

Subalpine fir 203,541 (23.6) 65,349 (41.6) 9,411 (98.3) 0 NA 278,302 (19.9)

Engelmann spruce 193,228 (23.7) 6,059 (100.2) 0 NA 23,842 (71.3) 223,129 (21.9)

Nonstocked 54,381 (43.6) 12,118 (100.2) 5,587 (104.2) 11,921 (101.4) 84,007 (35.3)

Douglas-fir 51,568 (45.8) 24,235 (70.6) 0 NA 0 NA 75,803 (38.2)

Aspen 47,690 (50.3) 0 NA 0 NA 0 NA 47,690 (50.3)

Limber pine 11,858 (101.2) 0 NA 0 NA 0 NA 11,858 (101.2)

Total 1,618,209 (7.3) 688,363 (12.1) 14,999 (72.9) 101,458 (32.5) 2,423,029 (5.5)

Figure 24—Mean density of live 

whitebark pine (number of trees per 

acre) by forest type, (a) for trees 

measured less than 5.0 inches in 

diameter, and (b) those larger than 

5.0 inches in diameter. 

0

5

10

15

20

25

30

35

40

45

50

Whitebark pine stems per acre

Diameter class (inches)

(b)

0

100

200

300

400

500

600

700

800

900

Whitebark pine stems per acre

Diameter class (inches)

Whitebark pine

Lodgepole pine

Engelmann spruce/subalpine fir

Subalpine fir

Engelmann spruce

(a)

<1.0 1.0-2.9 3.0-4.9

5.0-6.9 7.0-8.9 9.0-10.9 11.0-12.9 13.0+
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 49

Mean density of live and dead whitebark pine by size class and by major ownership group was also compared (fig. 25). Throughout Wyoming, there are more live 

than dead whitebark pines in the smallest size class (5.0–6.9 inches diameter), approximately equal densities of live and dead whitebark pines in the 7.0–8.9 inch size 

class, and more dead trees than live in size classes above 9.0 inches. However, this 

pattern varies by ownership. In all size classes smaller than 13.0 inches in diameter, 

there are more live than dead whitebark pines on NPS lands, although the density of 

live trees in most size classes is lower than Statewide estimates. This is consistent 

with the results presented in the Periodic to Annual Inventory Comparisons section 

of this report, which found that basal area of live whitebark pine in Wyoming has 

declined by more than half since the early 2000s while basal area of dead whitebark 

pine has increased nearly four-fold (figs. 18 and 19).

One way to assess the overall trends within a tree population is to compare 

rates of mean annual growth and mortality. FIA quantifies growth and mortality in 

terms of the volume that was added by live trees and the volume lost in the form 

of trees that recently died. Whitebark pine in Wyoming experienced mean annual 

gross growth of 7.1 million cubic feet per year during 2011–2015, compared to 64.6 

million cubic feet per year of mortality. Thus, Wyoming’s whitebark pine have experienced a net loss of 57.5 million cubic feet per year. This is equivalent to about 24 

cubic feet per acre per year, given that there are 2.4 million acres in Wyoming with a 

Figure 25—Mean density of live and dead whitebark pine (number of trees per acre) for trees at least 5.0 inches in 

diameter, by ownership group. Data are based on measurements from 222 plots Statewide (all plots), 151 plots on 

National Forest System lands (NFS plots), and 60 plots on National Park Service lands (NPS plots). 

0

2

4

6

8

10

12

14

16

5.0-6.9 7.0-8.9 9.0-10.9 11.0-12.9 13.0+

Whitebark pine stems per acre

Diameter class (inches)

Live trees, all plots

Dead trees, all plots

Live trees, NFS

Dead trees, NFS

Live trees, NPS

Dead trees, NPS
50 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

whitebark pine component (table 9). A longer-term perspective on these growth and 

mortality rates can be found in the Periodic to Annual Inventory Comparisons section of this document, which reported that mortality rates have increased by an order 

of magnitude, and net growth has declined from a slightly positive net growth to a 

large, negative net growth rate, since the early 2000s (fig. 19). Negative net growth 

indicates that mortality rates are higher than gross growth rates on a volumetric basis, 

and thus declines may continue to be observed in the coming years.

To examine the causes of recent mortality on FIA plots, we examined the causal 

agents for all whitebark pine that recently died (table 10). Out of a total of 720 trees 

that likely died no more than 5 years prior to measurement, 502 were determined 

to have been attacked by insects, primarily bark beetles. Other important mortality 

agents were fire (112 trees) and disease (90 trees, primarily rust). To illuminate the 

extent to which these mortality agents continue to affect live trees in Wyoming, the 

various damaging agents that were recorded on live trees were examined (table 11). 

Of the 1,075 live whitebark pine that were measured on 222 plots in Wyoming, 

822 had no damages recorded. Less than 5 percent of live trees showed evidence of 

Table 10—Number of whitebark pine that were estimated to have likely died no more than 5 years prior to measurement on 222 FIA plots, by causal mortality agent and field-designated forest type.

Mortality agent

Forest type Insects Disease Fire Other Total by forest type a

Douglas-fir 2 0 0 0 2

Engelmann spruce 99 0 0 3 102

Engelmann spruce/subalpine fir 164 30 0 1 195

Subalpine fir 23 12 12 0 47

Lodgepole pine 39 4 16 6 65

Whitebark pine 175 44 84 6 309

Total by causal agent 502 90 112 16 720

a Includes weather, competition/suppression, and unknown causes. 

Table 11—Number of live whitebark pine trees on 222 FIA plots, by damaging agent and field-designated forest type. Damaging 

agents that were recorded on less than 30 trees are not shown. Insects were primarily bark beetles. Disease was primarily rust. 

Causes of dead or broken tops were unknown. Form defects include crooks and forks in the tree bole. 

Damaging agent

Total by 

forest 

Forest type type

No 

damage Insects

Rust and 

other 

diseases

Dead or 

broken 

top

Form 

defect

Open 

wound

Other 

damages

Douglas-fir 3 0 0 0 0 0 0 3

Engelmann spruce 36 2 0 3 4 2 1 48

Engelmann spruce/subalpine fir 217 11 11 15 18 8 1 281

Subalpine fir 40 0 9 2 3 1 1 56

Lodgepole pine 156 0 5 8 4 3 0 176

Whitebark pine 370 19 25 15 56 14 12 511

Total by damaging agent 822 32 50 43 85 28 15 1,075
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 51

insects or disease damage. This may indicate that the high recent mortality of whitebark pine was episodic rather than constant, and future remeasurement of these plots 

will help clarify the ongoing rate and direction of trends in growth and mortality.

The smallest size classes of whitebark pine show patterns in growth, mortality, and density that do not mirror those observed in the larger size classes. First, 

the highest seedling densities were observed within stands dominated by lodgepole 

pine (fig. 24a), and the area of the Lodgepole pine forest type with a whitebark pine 

component is nearly twice as large as the area covered by the Whitebark pine forest 

type (table 9). Given the high mortality rates in larger size classes across all forest 

types and ownership groups, efforts to manage for whitebark pine may benefit from 

focusing on areas with high densities of seedlings and small trees. Second, whitebark pine smaller than 7.0 inches in diameter continue to have positive net growth, 

or gross growth rates that exceed mortality rates (fig. 26). The positive net growth in 

this small size class, relative to negative net growth in larger size classes, reinforces 

previous studies showing that both blister rust and mountain pine beetle shift stands 

toward smaller size classes (Field et al. 2012; Meyer et al. 2016).

A recent evaluation of the relative impacts of mountain pine beetle and white 

pine blister rust on whitebark pine population growth found that areas without mountain pine beetle had positive growth in terms of numbers of stems, even when blister 

rust was present (Jules et al. 2016). Therefore, if the recent mountain pine beetle 

epidemic is episodic and beetle populations return to endemic levels, it is possible 

that the dramatic declines observed thus far may slow or eventually cease. However, 

it is possible that the mortality up to this point has diminished the ability of whitebark 

pine to reproduce sufficient cones, and future population viability may be determined 

0 

2 

4 

6 

8 

10 

12 

14 

5.0-6.9 7.0-8.9 9.0-10.9 11.0-12.9 13.0-14.9 15.0-16.9 17.0-18.9 19.0-20.9 21.0-22.9 23.0+ 

Mean annual volume (cubic feet per year) 

Diameter class (inches) 

Gross growth Mortality 

Figure 26—Mean annual gross growth and mortality of whitebark pine at least 5.0 inches in diameter. 
52 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

more by survival of seedlings and small trees (McCaughey et al. 2009). To date, the 

FIA program has measured half of the annual plots in Wyoming and will collect 

more data during 2016–2020 to help answer questions such as these.

Snags as Wildlife Habitat

Standing dead trees (snags) are important habitat features in forested landscapes. A multitude of organisms utilize snags at some point in their life history, 

including at least one-fourth of all western bird species (Hutto 2006; McClelland 

et al. 1979). A handful of bird species act as primary excavators of nest sites in 

snags. These birds create a cavity during one breeding season but often abandon 

it and create a new cavity the following year. The old cavities are then occupied 

by secondary cavity-nesting birds. Secondary cavity-nesters do not excavate their 

own nest sites and are dependent on primary excavators for their nest cavities. The 

suitability of an old cavity for a secondary cavity-nester often depends on the species of primary cavity-nester that created it. Several mammal species, such as fishers, bats, and black bears, also use old cavities for denning and resting (Bull 2002).

The size of a snag is an important feature for many species, as larger snags 

tend to have a longer retention time, provide better thermal insulation, and can provide better protection from predators than smaller snags (Bull 2002 in Hutto 2006; 

Thomas et al. 1979). The height of a snag is also an important attribute for predator avoidance and thermal regulation. The Wyoming Game and Fish Department 

(WGFD) recommends one snag larger than 20 inches in diameter, four snags between 10 and 20 inches in diameter, and two snags between 6 and 10 inches in 

diameter per acre of forested land, with the 20+ inch trees being important for most 

species of wildlife. In addition, WGFD suggests all snags retained for wildlife 

should be taller than 6 feet (Oneale 2002).

Estimates of densities by stand age and forest-type group were assessed 

based on WGFD recommendations for small (6–9.9 inches diameter), medium 

(10–19 inches diameter), and large (greater than 20 inches diameter) snags. We 

only report forest-type groups that met snag density requirements in at least one 

age class. Missing data in a given age class either reflects no snags found in that 

forest-type group and age class or that there were no FIA plots sampled in that age 

class for that forest-type group. All density estimates were confined to snags that 

are equal to, or greater than, 6 feet in height. In addition, the acreages of forest-type 

group by age class that met all snag size-class densities thresholds were estimated.

Recommended small snag densities were met by almost all forest types and 

age classes (fig. 27). The recommended densities for medium diameter snags were 

not met in some of the younger age classes of the Ponderosa pine, Pinyon/juniper, 

and Aspen/birch forest-type groups. In addition, Pinyon/juniper in the 161–200 

year age class does not meet medium-size snag recommendations (fig. 28). The 

Other western softwoods group, which includes both limber pine and whitebark 

pine, met target densities for large-size snags in the two oldest age classes, as well 

as the youngest (fig. 29). The Douglas-fir group met recommended densities for 

large-size snags in three age classes (fig. 29).
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 53

Large acreages of sufficient density of all size classes of snags were found 

across five important forest-type groups, and across all but one age class (fig. 30). 

There is very little acreage with sufficient snags of any size in the 41- to 80-year 

age class, with the exception of the Fir/spruce/mountain hemlock forest-type 

group, which met all snag targets in every age class (fig. 30). Younger stands in 

the 41- 80-year range are still relatively productive, where snags are less likely. 

Also, there are many fewer stands in 41- to 80-year stand-age classes than would 

be expected (see the Stand Age section).

Snags suitable for a large suite of cavity-nesting birds are found in a wide 

range of forest types and age classes, but the highest density of these snags are 

found in older (over 120 years) stands of softwoods. The species lodgepole pine, 

subalpine fir, and Engelmann spruce are presently providing the majority of 

snags for wildlife. An exception to this trend is the high density of snags found 

in the Aspen/birch forest-type group. Aspen forests are particularly important for 

some primary and secondary nesting birds because of the relationship between 

diseased aspen, primary excavators, and secondary nesters (Hart and Hart 2001). 

Nonstocked forests (age class of zero), where large stand-replacing events such as 

fire or insect infestation have created an abundance of snags, are meeting recommended densities in all but the largest diameter class.

0 

10 

20 

30 

40 

50 

60 

70 

80 

0-40 41-80 81-120 121-160 161-200 201+ 

Snags per acre 

Stand-age (years) 

Fir / spruce / mountain hemlock 

Douglas-fir 

Lodgepole pine 

Other western softwoods 

Nonstocked 

Ponderosa pine 

Pinyon / juniper 

Aspen / birch 

Figure 27—Density of small snags (6.0–9.9 inches diameter) by forest-type group and age class, Wyoming, 2011–2015. 

Minimum recommended density for small snags is 2. Only those forest-type groups that had at least one FIA plot record of 

a suitably sized snag are represented.
54 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

0-40 41-80 81-120 121-160 161-200 201+ 

Snags per acre 

Stand-age (years) 

Fir / spruce / mountain hemlock 

Douglas-fir 

Lodgepole pine 

Other western softwoods 

Nonstocked 

Ponderosa pine 

Pinyon / juniper 

Aspen / birch 

Figure 28—Density of medium snags (10.0–19.9 inches diameter) by forest-type group and age class, Wyoming, 

2011–2015. Minimum recommended density for medium snags is 4. Only those forest-type groups that had at least one 

FIA plot record of a suitably sized snag are represented. 

0 

1 

2 

3 

4 

5 

6 

7 

8 

0-40 41-80 81-120 121-160 161-200 201+ 

Snags per acre 

Stand-age (years) 

Fir / spruce / mountain hemlock 

Douglas-fir 

Lodgepole pine 

Other western softwoods 

Nonstocked 

Ponderosa pine 

Figure 29—Density of large snags (greater than 20 inches diameter) by forest-type group and age class, Wyoming, 

2011–2015. Minimum recommended density for large snags is 1. Only those forest-type groups that had at least one 

FIA plot record of a suitably sized snag are represented.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 55

Variables other than snag diameter and stand age need to be considered when 

predicting suitable wildlife habitat for forest-dwelling species. Proximity to forest 

edge and density of live trees is important to many cavity-nesting birds. The state 

of decay of a tree and its distance to foraging also plays a role in nest site suitability. As such, these estimates should be considered a liberal estimate of potential 

habitat for cavity-nesting species in Wyoming.

Understory Vegetation

The structure and composition of understory vegetation can characterize the 

diversity, productivity, and potential wildlife habitat structure in forest ecosystems. 

FIA collects understory vegetation data using two distinct protocols that characterize overall vegetation structure as well as species composition. Under the vegetation structure protocol, field crews record the height class and percent cover that 

is occupied by each of four plant growth habits: forbs, graminoids, shrubs, and 

understory trees, which are defined as trees less than 5 inches in diameter. Under 

the species composition protocol, height class, growth habit, and percent cover are 

recorded for plant species that individually occupy at least 3 percent of the ground 

area. If more than four species in a growth habit occupy greater than 3 percent of 

the surface area of a plot, then only the four most abundant species are recorded.

0 

50 

100 

150 

200 

250 

300 

0-40 41-80 81-120 121-160 161-200 201+ 

Acres (thousands) 

Age-class (years) 

Fir / spruce/ mountain hemlock 

Douglas-fir 

Lodgepole pine 

Other western softwoods 

Nonstocked 

Figure 30—Estimates of forest land area that meets recommended snag densities for all three size classes (6–9.9 

inches, 10–19.9 inches, and greater than 20 inches diameter) concurrently, by age class, Wyoming, 2011–2015. 
56 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

The average percent cover varies among each plant growth habit across all 

forested land, among forest types, and among the 10 most abundant forest types 

in Wyoming (fig. 31). Graminoids made up more understory cover than the other 

three growth habits in four of the forest types analyzed. Graminoid cover ranged 

from 8.9 percent in the Engelmann spruce/subalpine fir forest type to 31 percent 

in the Ponderosa pine forest type. Shrubs and understory trees both dominated understory cover in three other forest types each. Shrub cover averaged 9.3 percent 

(Rocky Mountain juniper) to 19.2 percent (Lodgepole pine) and provided the highest understory cover among all forest types. Understory trees were most prevalent 

in Lodgepole pine and Subalpine fir forest types, and ranged from 2.8 percent in 

nonstocked forests to 19.3 percent in Lodgepole pine. On average, forbs were not 

a dominant cover in any forest type in Wyoming. Forbs were more abundant in 

nonstocked areas than any other forest type and covered the least amount of area 

in the Rocky Mountain juniper forest type.

Almost 600 individual plant species were recorded on Wyoming’s forest inventory subplots. While subalpine fir was by far the most frequently encountered 

understory species, grouse whortleberry (Vaccinium scoparium) covered more 

area on average where it was found (table 12). Forbs were found on the fewest 

subplots (n = 3,088) but showed the greatest diversity of the growth habits with 

295 species measured at 3 percent cover or greater. Conversely, trees showed the 

least diversity with only 32 species being measured in the understory. Shrubs were 

found most frequently, having been recorded on 3,907 subplots.

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 

Rocky Mountain juniper 

Douglas-fir 

Ponderosa pine 

Engelmann spruce 

Engelmann spruce/ Subalpine fir 

Subalpine fir 

Lodgepole pine 

Whitebark pine 

Aspen 

Nonstocked 

All forested land 

Average percent cover 

Forest type 

Understory trees 

Shrubs 

Graminoids 

Forbs 

Figure 31—Average percent cover of understory vegetation by growth habit and forest type, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 57

Invasive and Noxious Species

FIA field crews record any instance where a noxious weed is found on a plot that 

contains a forested condition. This allows the spatial and temporal extent of these species to be documented when plots are revisited. Of the 951 plots sampled in Wyoming 

(2011–2015), 118 (12.4 percent) plots harbored an invasive plant (table 13). Eleven 

different invasive species were recorded, with Canada thistle (Cirsium arvense) accounting for 60 percent of the occurrences. Canada thistle was also found in the most 

diverse suite of forest types, occurring in every forest type in which an invasive was 

found. Gypsyflower (Cynoglossum officinale) was a distant second with 15 total occurrences, almost half (n = 7) of which were found in the Bur oak forest type. The 

Nonstocked forest type had by far the highest occurrence of invasive species, containing 29 percent (n = 34) of the occurrences. This is not surprising considering nonstocked forests are often created by disturbances that can facilitate invasion of undesirable plant species. Bur oak and Lodgepole pine were the next most infested forest 

types, with presence in 16 and 14 plots, respectively. The number of plots with invasive species was too small to permit analysis of site factors that may allow or facilitate 

invasion by weedy species. However, as Wyoming’s forest inventory completes its 

first annual cycle, additional data may illuminate such factors. For example, specific 

forest types may be more prone to noxious plant infestation than others. Factors that 

may affect a site’s propensity for infestation include soil conditions, accessibility to 

livestock grazing, road and foot traffic, or high frequency of both natural and humaninduced disturbance such as burning or flooding, and/or edge effects.

Table 12—The most frequently recorded understory plant species in each growth habit the number of subplots where they 

occurred, and average percent cover, Wyoming, 2011–2015.

Growth habit Species Common name Number of subplots Average percent cover

Forbs

Arnica cordifolia heartleaf arnica 399 6.4

Fragaria virginiana Virginia strawberry 164 5.0

Lupinus argenteus silvery lupine 154 6.4

Thalictrum occidentalis western meadow-rue 111 5.3

Carex geyeri Geyer’s sedge 334 11.0

Graminoids

Carex spp. sedge species 333 16.8

Calamagrostis rubscens pinegrass 315 13.4

Poa spp. bluegrass 259 14.5

Abies lasiocarpa subalpine fir 1031 14.2

Trees

Pinus contorta lodgepole pine 735 17.3

Picea engelmannii Engelmann spruce 450 6.9

Pinus albicaulis whitebark pine 250 7.2

Vaccinium scoparium grouse whortleberry 935 25.9

Shrubs

Juniperus communis common juniper 357 9.0

Artemisia tridentata big sagebrush 327 12.6

Mahonia repens creeping barberry 187 6.4
58 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Table 13—List of invasive species found in Wyoming’s forest by forest type and number of occurrences. Wyoming, 2011–2015. Scientific name Common name Forest type Rocky Mountain juniper Douglas- fir Ponderosa pine Engelmann spruce Engelmann spruce/ subal- pine fir Subalpine fir Lodgepole pine Limber pine Whitebark pine Bur oak Aspen Non- stocked Cirsium arvense hardheads - 1 - - - - - - - - - 3 Carduus acanthoides spiny plumless thistle - - - - - - - - - - - 1 Carduus nutans nodding plumless thistle - - - - - - 1 - - - 1 3 Cardaria pubescens hairy whitetop - - - - - - - - - 3 - - Centaurea diffusa diffuse knapweed - - - - - - - - - - - 3 Cirsium arvense Canada thistle 3 6 3 6 7 7 13 6 2 - 4 14 Convolvulus arvensis field bindweed - - - - - - - - - 3 - - Cynoglossum   officinale Gypsyflower - 1 5 - - - - - - 7 - 2 Linaria dalmatica Dalmatian toad flax - - - - - - - - - - - 4 Linaria vulgaris butter and eggs - - 2 - - - - - - - - 4 Onopordum acanthium Scotch cotton thistle - - - - - - - - - 3 -
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 59

Current Issues in Wyoming’s Forests

Bark Beetle Infestation

Increased bark beetle populations have been a significant contributor to tree 

mortality in the western United States over the past few decades. Recent State reports for Colorado and Utah have indicated elevated levels of at least four important 

tree-killing bark beetles: spruce beetle (Dendroctonus rufipennis) on Engelmann 

spruce; mountain pine beetle on lodgepole pine, ponderosa pine, limber pine, and 

whitebark pine; Douglas-fir beetle (Dendroctonus pseudotsugae) on Douglas-fir; 

and western balsam bark beetle (Dryocoetes confusus) on subalpine fir (Thompson 

et al. 2017; Werstak et al. 2016). Species-level causal mortality agents are not 

recorded by FIA field crews; however, many of these insects are species- or genusspecific and attack multiple trees per plot during epidemics. Therefore, it is reasonable to speculate they are the primary drivers of insect-caused tree mortality.

Insect-caused mortality in Wyoming was highest (by acres of forest land) 

in the Fir/spruce/mountain hemlock forest-type group, where 24 percent was affected, which indicates elevated levels of spruce beetle and probably western balsam bark beetle (table B8). Mortality of Engelmann spruce was much higher than 

subalpine fir (fig. 6), suggesting that spruce may be much more affected by beetles. 

The second highest insect-caused mortality (by acres of forest land) was in the 

Lodgepole pine forest-type group, where 14 percent was affected (table B8). Of 

particular note is the other western softwoods group, which includes the important 

wildlife species of whitebark pine, and limber pine, where 21 percent has been affected, most likely by the mountain pine beetle (see the Whitebark Pine Status and 

Trends section). In addition, approximately 13 percent of the Douglas-fir foresttype group has been affected by insects (table B8).

Spruce Beetle

The spruce beetle is native to the Engelmann spruce forests of the Interior 

West, including Wyoming. At endemic population levels the spruce beetle prefers 

mature, large individual Engelmann spruce in stands of high density, and on productive sites (Schmid and Frye 1976). However, when spruce beetles successfully 

mass-attack individual spruce, their populations may increase to epidemic levels 

where mortality levels of greater than 90 percent are possible at scales much larger 

than individual stands (Schmid and Frye 1977).

Surprisingly, reported insect-caused mortality in the Fir/spruce/mountain 

hemlock group from the previous Wyoming report was very low, approximately 

3 percent of the area (Thompson et al. 2005). While the most recent periodic data 

are not strictly comparable to the annual design, this still represents considerable 

additional mortality that has occurred over a decade later (2011–2015). The average annual mortality for the Fir/spruce/mountain hemlock forest-type group was 

substantial, the highest of any forest type, at approximately 283 million cubic 

feet (table B26). Nearly 87 percent of that mortality occurred on NFS ownership, 
60 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

where approximately 81 percent of the area of the Fir/spruce/mountain hemlock 

forest-type group occurs.

Mortality attributable to insects in the Fir/spruce/mountain hemlock foresttype group appears to have been constant since the first annual reporting period, averaging approximately 16 million cubic feet (fig. 32). With only 4 years of 

evaluations (and 5 years of data) it is hard to conclude that there is any trend in 

insect-caused mortality in Wyoming. Some insect-caused mortality of subalpine 

fir within this forest-type group is likely attributable to the western balsam bark 

beetle; however, given the large differences in mortality between the True fir and 

Engelmann spruce species groups (table B27), it is likely that the spruce beetle has 

caused the most mortality. Engelmann spruce and subalpine fir mortality caused by 

insects appears to be fairly ubiquitous across the State (fig. 33).

Mountain Pine Beetle

The mountain pine beetle is a native insect hosted by most species of pine. 

In Wyoming, mountain pine beetle populations have been elevated for the entire 

0 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20 

Periodic-2000 2011-2012 2011-2013 2011-2014 2011-2015 

Mortality volume (million cubic feet per acre) 

Annual 

Inventory type 

Fir/spruce/mountain hemlock Lodgepole pine 

Figure 32—Insect-caused mortality of all trees on forest land (million cubic feet per year) for the two most-impacted 

forest-type groups: Fir/spruce/mountain hemlock, where the causal agents were likely spruce beetle and western balsam 

bark beetle; and Lodgepole pine, where the primary contributor to mortality was likely mountain pine beetle. Wyoming, 

2011–2015. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 61

annual reporting period (2011–2015), which is consistent with outbreak timing in 

neighboring States, such as Colorado (Thompson et al. 2017), Idaho (Witt et al. 

2012), and Montana (Menlove et al. 2012) (fig. 32). Four important pine species 

in Wyoming host mountain pine beetle: lodgepole pine, ponderosa pine, whitebark 

pine (see the Whitebark Pine Status and Trends section), and limber pine. While 

risk factors indicating susceptibility of pines to mountain pine beetle are less wellknown than risk factors for Engelmann spruce susceptibility to spruce beetle, it is 

thought that stands of high density and large individual trees are where beetles are 

most likely to successfully rear a brood (Fettig et al. 2013).

Low levels of lodgepole pine mortality attributable to insects were reported 

in the previous periodic report, and the first four evaluations for the annual inventory in Wyoming indicate just over 10 million cubic feet were killed, on average 

(fig. 32). Mortality of lodgepole pine appears to be occurring across the State, 

with particularly strong prevalence in the Greater Yellowstone Ecosystem, Wind 

River Range, and Wyoming Range (fig. 33). Interestingly, plots with limber pine 

mortality occur primarily in the interior basins of the State where it commonly occurs, in particular on the eastern slopes of both the Wind River Range and Greater 

Yellowstone Ecosystem (fig. 33).

Figure 33—Plot locations where 

individual trees, by species, were 

noted in the field to have been 

killed by insects, Wyoming, 2011–

2015. This methodology differs from 

Forest Health Protection, Aerial 

Detection Surveys. (Note: plot 

locations are approximate; some 

plots on private land were randomly 

swapped.)
62 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Aspen Status and Trends

Aspen is the widest-ranging species in North America. It is present in all States 

in the Interior West and occupies a wide elevational range—from 2,000 feet in northern Idaho to 11,700 feet in Colorado. It is also found on a diverse range of sites and 

is present in 26 of the forest types that occur in the Interior West. The species is 

intolerant of shade and relatively short-lived, which makes it prone to replacement 

by conifers through successional change. In the Interior West, aspen also reproduces 

infrequently by seeding but likely relies primarily on root sprouting for reproduction. 

Aspen responds well to fire and cutting, and it is able to dominate heavily disturbed 

sites. In addition, there is some evidence that aspen is able to persist in coniferdominated forests by exploiting gaps in the conifer canopy that are caused by insects, 

disease, windthrow, and other smaller-scale disturbances.

In recent years there has been concern about the future of aspen on the landscape, primarily due to the characteristics of aspen and how they relate to changes 

in disturbance regimes. The earliest concerns were related to successional change in 

the Interior West, where fire suppression has decreased disturbance rates and, as a 

result, aspen regeneration rates. In addition, it has been shown that large populations 

of herbivores can inhibit aspen regeneration (Hessl and Graumlich 2002). The lack 

of disturbance allows conifers to gain dominance where they are present, and in pure 

aspen stands, damage of regeneration by ungulates could lead to loss of senescing 

overstory trees without replacement. More recent concerns are related to a period of 

drought that has had an impact on aspen and other forest types (Shaw et al. 2005; 

Thompson 2009). Drought appears to have contributed to mortality in many lowelevation stands (Worrall et al. 2008), and in some of these regeneration is either 

lacking or suppressed by herbivores.

The current inventory of Wyoming shows that there are over 619,000 acres of 

the Aspen forest type in Wyoming (table B3), as compared to nearly 694,000 acres 

found during the 2000 periodic inventory (Thompson 2005). When considering all 

acres where aspen occurs, the current inventory shows that aspen is currently present 

on over 1.59 million acres, as compared to over 1.85 million acres during the 2000 

inventory. This result suggests a decrease in the area of aspen over the past 15 years, 

with the aspen type currently occupying about 89 percent of the former area, and all 

land with aspen present occupying about 86 percent of the former area. However, 

the two inventories are not directly comparable because of a change between inventories in the lower threshold of what is considered forest land (from a minimum of 5 

percent cover previously, to a minimum of 10 percent cover currently). When considered as a percentage of total forest area, the Aspen forest type accounted for 6.0 

percent of Wyoming forest land in 2000, as compared to 5.9 percent in the current 

inventory. When considering all area with aspen present, the comparable percentages 

are 16.2 in the 2000 inventory and 15.1 in the current inventory. While these differences suggest some decline in aspen area, both as a forest type and in area present, 

they are relatively small, not statistically significant, and may change because only 

50 percent of the annual inventory cycle has been completed.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 63

Another way to normalize between inventories is to compare volume or biomass density. Using the 2000 values of 1.85 million acres with aspen present and 

580 million cubic feet of live aspen volume results in an average volume of 313.0 

cubic feet of live aspen per acre (fig. 34). The equivalent computation in the current inventory gives 234.4 live cubic feet per acre, or just under 75 percent of the 

2000 average (fig. 34). This comparison also suggests a relative decline in aspen 

across Wyoming. However, the estimates produced from only the annualized inventory for the past 4 years indicated a current increasing trend, from a low of 

136.8 cubic feet per acre in 2012 to the estimate of 234.4 cubic feet per acre in 

2015 (fig. 34). This interpretation is made with caution, though, because the 2012 

estimate was made using only 20 percent of the plots in the State, and the current 

estimate is based on half of a full inventory cycle.

Assuming that the current trend is sustained through the remainder of the 

inventory cycle, there are at least two possible interpretations of the pattern. One 

possibility is that the pattern is an artifact of the inventory and, during the first 1 

or 2 years of annual inventory, sampling noise among the plots included in the 

sample under-sampled aspen by chance. In this scenario, the pattern is mostly attributable to sampling noise. An alternative interpretation is that there was a relatively large decline in aspen volume during the period between inventories, and 

0

50

100

150

200

250

300

350

1995 2000 2005 2010 2015 2020

Average aspen volume (cubic feet per acre)

Inventory year

Figure 34—Trend in average aspen volume (cubic feet per acre) between the periodic inventory (2000) and the first 5 

years (2011–2015) of the annual inventory. 
64 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

that annual inventory is capturing the recovery of aspen volume. It is possible that 

both mechanisms are involved, precluding any definitive explanation at this time. 

Aspen volume trend will be monitored closely as future annual panels are added 

to the current inventory.

Whether this fluctuation is due to sampling error or represents a real trend will 

require additional years of monitoring. However, even with the limited amount of 

information available, it is possible to develop some expectations about possible 

future trends. The difference between the low estimate of 136.7 cubic feet per acre 

and the previous estimate of 313.0 cubic feet per acre represents an average annual 

decrease of about 26 cubic feet per acre per year. The apparent trend of the past 4 

years of annual inventory represents an increase of volume of over 24 cubic feet 

per acre per year—nearly an offsetting rate. This would suggest that recovery to 

the 2000 volume density would require between 3 and 4 years from the present in 

the absence of unusual levels of disturbance.

Is 24 cubic feet per acre per year a realistic expectation for aspen, given that 

recovery rate is limited by the amount of live standing volume and inherent site 

quality, while decline has no limits on the speed of change (e.g., stand-replacing 

fire)? This question is difficult to answer with any certainty for the aspen population. It is worth noting that the definition of timberland is that which has the potential to produce at least 20 cubic feet per acre per year of wood volume. Aspen is a 

relatively productive forest type in the Interior West, and 77 percent of the Aspen 

forest type in Wyoming is classified as timberland. Furthermore, just under 18 

percent of the Aspen forest type in Wyoming is classified as being able to produce 

at least 50 cubic feet of wood per acre per year at the age of culmination of mean 

annual increment. So, while there is much uncertainty with respect to future trends, 

aspen has the capacity to recover volume quickly after a period of decline.

Fire in Wyoming’s Forests

Fire is an important disturbance that influences the structure and dynamics of 

Wyoming’s forests. In some forest types, such as Ponderosa pine, fire can maintain 

open stands and stimulate the growth of grasses and forbs in the understory. In 

other forest types, such as Aspen and Lodgepole pine, fire is an important agent of 

regeneration. Throughout the Interior West, a century of fire suppression has led to 

a buildup of fuels and stand densification, which may lead to uncharacteristically 

intense fires (Reinhardt et al. 2008). Areas that burn intensely may experience slow 

regeneration, but others may recover relatively quickly—this depends in part on 

species’ life history traits. For example, the area inside the boundary of the large 

1910 fires in Idaho and Montana (Cohen and Miller 1978; Egan 2009; Pyne 2008) 

now carries about the same amount of live tree volume per acre as areas outside the 

fires, although the mean stand age is somewhat lower and the volume is generally 

distributed among smaller trees (Wilson et al. 2010).

To characterize fire in Wyoming, data from the Monitoring Trends in Burn 

Severity (MTBS) project were used. MTBS is an interagency effort, conducted 

and maintained by the USDA Forest Service Remote Sensing Applications Center 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 65

and the U.S. Geological Survey National Center for Earth Resources Observation 

and Science. The purpose of the MTBS project is to map the perimeters and severities of large wildland fires (including wildfire, wildland fire use, and prescribed 

fire) across all lands of the United States. In the western States, the project includes 

all fires larger than 1,000 acres (Eidenshenk et al. 2007) but usually captures some 

patches that are below that threshold. The analysis presented here is based on fire 

perimeters identified by the MTBS program between 1984 and 2015 and FIA plot 

data collected in Wyoming under the periodic inventory (1998–2002) and the annual inventory (2011–2015).

The MTBS program mapped 334 fires and fire complexes in Wyoming between 1984 and 2015, with named fire areas ranging from near the minimum 

mapped area of 1,000 acres to over 500,000 acres. The total area burned over the 

32-year period, determined by summing all mapped fires, was 3,757,266 acres. 

After accounting for overlap (areas burned two or more times), the unique burned 

area was 3,671,199 acres. The mean burned area was 11,249 acres and the median 

was 3,058 acres. Of the FIA plot locations measured between 2011 and 2015, 315 

fell within 109 of these burned areas (fig. 35). Although the number of plots falling inside fire perimeters is expected to increase substantially as the full inventory 

cycle is completed, the fact that over half of the mapped areas are smaller than 

6,000 acres results in the expectation that many of them will never be sampled by 

an FIA plot. However, the systematic sample provided by the FIA inventory makes 

Figure 35—Fire boundaries mapped for the period 1984–2015, with FIA plot locations and status from Wyoming, 

2011–1015.
66 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

it possible to make estimates of forest/nonforest status, forest type, and other characteristics of burned areas. The FIA plot-based estimate of unique burned area 

was 3,594,433 acres, which was within approximately 2 percent of the MTBS 

perimeter-based calculation.

Wyoming has a somewhat unusual fire history within the MTBS record, as 

compared to other Interior West States. In the beginning of the MTBS record (1984–

1987), relatively little burned area was mapped—only 36,296 acres. However, the 

large fires and fire complexes of 1988, most of which are known collectively as the 

Yellowstone Fires, brought the cumulative area burned in Wyoming to 1.59 million acres in 1 year. During the 27 years following the large 1988 fires, burned area 

in Wyoming has accumulated at a relatively steady pace, totaling 2.0 million additional acres and averaging almost 74,000 acres per year (fig. 36). Of the 27-year 

total area burned, nearly 814,000 acres (41 percent) were on forest land and nearly 

1.2 million acres (59 percent) were on nonforest land. If the current annual rate of 

acres burned and the forest:nonforest ratio remain steady, by the year 2025 over 

800,000 additional acres could be burned in Wyoming, with about 330,000 acres 

of that in forest land status, and about 470,000 acres on nonforest status.

Because the fires of 1988 make up such a large portion of the total area burned 

in Wyoming over the past 31 years, the area affected by them is worth discussing 

separately. First, in contrast to the long-term forest:nonforest ratio of about 41:59, 

0.0 

0.5 

1.0 

1.5 

2.0 

2.5 

3.0 

3.5 

4.0 

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 

2011 

2012 2013 2014 2015 

Cumulative acres burned (millions) 

Year 

Forest Nonforest 

Figure 36—Cumulative area of forest land and nonforest land burned in Wyoming, 1984–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 67

over 80 percent of the area burned in 1988 was forest land. Second, forest land 

in the Greater Yellowstone Ecosystem occurs in much different abundance than 

across Wyoming overall (fig. 4). Instead of using calculated forest type, as in much 

of this report, this analysis uses the crew-identified forest type. This is useful in the 

case of disturbed forest because stands of many forest types with low stocking will 

be represented in the calculated “nonstocked” type. In the field, crews identify the 

forest type regardless of stocking or tree tally, so they identify nonstocked forest as 

the likely future forest type. By this method, Lodgepole pine is the most abundant 

forest type in the State, occupying nearly 29 percent of forest area. The allied forest types of Engelmann spruce, Engelmann spruce/subalpine fir, and Subalpine fir 

collectively make up another 29 percent. However, the Lodgepole pine forest type 

occupies 69 percent of the area burned in the 1988 fires (fig. 37).

There are no data available to compare prefire conditions to the current inventory; however, it is likely that lodgepole pine’s adaptation to fire resulted in 

acreage gains. It is also possible that most of the postfire lodgepole pine area was 

dominated by lodgepole pine prior to the fire. In contrast, the allied spruce and fir 

types in the burned area added up to 27 percent, close to the Statewide proportion. At about 3 percent of the 1988 burned area, Douglas-fir occurred at a much 

lower proportion than Statewide (8.8 percent). Whitebark pine was also an exceptional case. Although whitebark pine is considered to benefit from fire (Keane et 

al. 2017), the whitebark pine proportion of the burned area (2 percent) was lower 

than the Statewide proportion (3 percent) and much lower than the proportion in 

Yellowstone National Park (10 percent; Thompson et al. 2005), even though the 

large fires burned areas surrounding many whitebark pine stands.

Finally, the current inventory reveals a trajectory of recovery from the 1988 

fires. Based on 1998–2002 periodic inventory plots that occur within 1988 fire 

3% 5% 

17% 

4% 

69% 

2% 

Forest types 

Douglas-fir Engelmann spruce 

Engelmann spruce/subalpine fir Subalpine fir 

Lodgepole pine Whitebark pine 

Figure 37—Proportions of area burned in 

1988 in Wyoming, by forest type. 
68 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

boundaries, an estimated 1.07 billion cubic feet of live volume occurred on 1.36 

million acres of forest land, for an average of 787.8 cubic feet per acre. The same 

calculation using the current inventory results in 1.08 billion cubic feet of live volume on 1.22 million acres of forest land, giving an average of 885.5 cubic feet per 

acre. Although the two estimates of area differ by about 10 percent, normalizing to 

per-acre values should provide a close approximation to the actual change within 

the burned area. This calculation also suggests that stands in the burned area are 

not yet near full stocking—the Statewide average for the unburned portion of forest land was 1876.1 cubic feet per acre in 2002.

The analysis of fire and fire effects in this section should be considered only 

a first approximation of fire effects on Wyoming’s forests, because the State is 

only half through the current inventory cycle. Completion of the current inventory 

cycle, which will occur in 2020, should allow a relatively detailed comparison of 

pre- and postfire conditions, using plots that were measured during both the current 

inventory cycle and the 2002 periodic inventory.

National Forest System Inventory

The National Forest System (NFS) controls over 5.8 million acres of land in 

Wyoming (table B2), which was previously described in terms of reserved and unreserved status in the Forest Land Ownership section. In practice, there are several 

administrative jurisdictions imposed within NFS lands that can affect the type of 

management being conducted, such as for timber harvesting. Land that is suitable 

for timber harvesting typically must exhibit reasonable growth rates, but it must 

also not be limited by other designations that restrict timber harvest activities. The 

“suitable timber base,” or areas suitable for timber harvest as categorized here, includes NFS land that is not already designated as wilderness, inventoried roadless, 

and other. The other category in Wyoming includes practical limitations—such as 

low productivity, steep slopes, and riparian buffers—and administrative limitations such as management objectives, wilderness study areas, and grasslands (see 

Forest Land Ownership section). In Wyoming, the relatively recent inventoried 

roadless ruling also resulted in a substantial portion of what was once considered 

suitable for timber production falling within the “suitable within roadless” land 

status (fig. 38, table 14).

Because FIA field crews do not collect information about land status within the NFS, this analysis represents a post-hoc assessment based on the overlap 

of multiple spatial layers in a geographic information system (GIS) provided by 

Regions 2 and 4, with FIA plot locations from the 2011–2015 Wyoming inventory. Using these layers, area, net volume, and mortality by land status within NFS 

national forests and grasslands were tabulated. Overlap between various GIS layers, and the inability of the layers to capture a few plots, resulted in estimates that 

were very close but not exactly the same as those produced by the core FIA tables 

(Appendix B).
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 69

Figure 38—Areas of suitable/unsuitable, reserved roadless National Forest Systems land, Wyoming.

Table 14—Area of forest land, in acres, by land status on National Forest Systems forest land in Wyoming, 2011–2015. 

Land status Acres

Suitable for timber production 797,298

Suitable inside roadless 354,795

Total suitable 1,152,094

Inventoried roadless 2,400,354

Designated wilderness 1,655,024

Other 996,326

Total not suitable 5,051,705
70 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Of the over 5.8 million acres of forest land under NFS ownership in Wyoming, 

the vast majority (approximately 81 percent) was categorized as unsuitable for 

timber production (table 14). Similarly, approximately 78 percent of net volume 

found on NFS ownership falls within the not suitable land status (table 15). While 

there are over a million suitable acres available for harvest in Wyoming, roughly 

one-fourth of that area falls within the inventoried roadless designation, potentially precluding those areas from harvest that requires road-building. The suitable 

land base falls largely within the Black Hills and Medicine Bow-Routt National 

Forests, with smaller portions also occurring in the Bighorn and Bridger-Teton 

National Forests (fig. 38).

Because NFS ownership makes up over half of the forest land in Wyoming, 

it is not surprising that the pattern of elevated mortality caused primarily by insects and fire is mirrored on NFS lands (table 16). Insects account for the largest 

percentage of volume mortality on both suitable and not suitable land status. As a 

percentage of acreage, on land that is suitable for timber production, both insects 

and disease have a similar proportion of mortality compared to all not suitable forest land (approximately 6 percent). This is not true of fire-caused mortality, where 

Table 15—Net volume of live trees (at least 5 inches in diameter), in million 

cubic feet, by land status on National Forest Systems forest land in 

Wyoming, 2011–2015. 

Land status All forest land

Suitable for timber production 1,349

Suitable inside roadless 912

Total suitable 2,261

Inventoried roadless 4,566

Designated wilderness 1,928

Other 1,576

Total not suitable 8,070

Table 16—Average annual mortality of trees (at least 5 inches in diameter), in thousand cubic feet, by land status on National Forest 

System forest land in Wyoming, 2011–2015.

Mortality (cause of death)

Land status Insect Disease Fire Animal Weather Vegetation

Unknown/ 

other

Logging/ 

human

Suitable for timber 

production 50.55 7.31 1.03 - 0.97 0.08 4.77 0.04

Suitable inside roadless 23.94 1.29 3.27 - 1.59 0.22 0.80 -

Total suitable 74.50 8.60 4.30 - 2.57 0.30 5.57 0.04

Inventoried roadless 149.33 9.39 13.82 0.04 4.54 0.95 7.95 -

Designated wilderness 101.54 19.72 53.05 0.03 2.72 0.05 9.24 -

Other 39.30 5.14 1.75 0.15 2.03 0.17 2.43 0.78

Total not suitable 290.17 34.24 68.62 0.22 9.29 1.16 19.63 0.78
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 71

there is proportionally more on unsuitable lands than on suitable lands. This is 

likely due, in part, to the ability to access and fight fires that start on the suitable 

land base.

Because of high levels of mortality, average annual net growth for the State 

(see the Forest Growth, Mortality, and Removals section) was negative for the 

2011–2015 time period. This pattern was also reflected on NFS lands for a number 

of important softwood species. For example, Engelmann spruce and lodgepole 

pine both exhibited negative net growth, irrespective of the land status (table 17). 

Important wildlife species such as whitebark pine and aspen exhibited negative 

growth in the not suitable land base. Across land status, subalpine fir and ponderosa pine both exhibited positive net growth. In contrast, on not suitable lands both 

blue spruce and Rocky Mountain juniper exhibited positive net growth. In areas 

that are suitable for timber production ponderosa pine, subalpine fir, and quaking 

aspen all exhibited a higher rate of growth than mortality (table 17).

Pinyon/Juniper Forest-Type Group

The Pinyon/juniper forest-type group is the third most abundant in Wyoming, 

encompassing 1.1 million acres (10.3 percent of forested area; table B4). Two forest types—Rocky Mountain juniper and Juniper forest types—make up the vast 

majority of acreage within the Pinyon/juniper forest-type group. Unlike other 

States in the Interior West that have large areas of the Pinyon/juniper forest-type 

group (Arizona, Colorado, Nevada, New Mexico, and Utah), where common 

pinyon (Pinus edulis) or singleleaf pinyon (Pinus monphylla) are widespread, in 

Wyoming there have only been two plots recorded with common pinyon. Therefore, 

in Wyoming this forest-type group characterizes almost entirely juniper species.

There is concern that juniper is encroaching into sagebrush steppe communities, which may have implications for sage grouse habitat. Because FIA considers 

lands with at least 10 percent tree canopy cover as forested, juniper issues in truly 

sagebrush or sagebrush-juniper ecotone areas cannot be assessed; that is, areas 

with less than 10 percent canopy cover. However, distributions of juniper ages for 

any forested plots with a juniper component can be investigated. The geographic 

distribution of juniper in Wyoming is highly varied (fig. 39) with subgroups occurring in the southwest corner, on the fringes of mountain ranges, and in the eastern 

plains. Stands classified as Juniper forest types include trees that exceed many 

centuries in age, with few plots less than 100 years old (fig. 40). On the other hand, 

juniper ages from trees located in other forest types are much younger (fig. 40). 

Many juniper ages in the eastern and southwestern portion of the State are less than 

100 years old, which suggests the possibility that they are younger stands. Another 

possibility is that they are re-establishing after settlement-era exploitation, which 

is impossible to tell in the absence of historical documentation or stand history 

reconstructions.
72 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Table 17—Average annual net growth of live trees (at least 5 inches in diameter), in million cubic feet, by species and land status on National Forest System forest land in Wyoming, 2011–2015. Species Land status Subalpine fir Engelmann spruce Blue spruce Whitebark pine Lodgepole pine Limber pine Ponderosa pine Douglas-fir Aspen Rocky Mountain juniper Suitable for timber production 2.71 -10.39 - -1.95 -28.79 -0.29 4.67 0.05 0.26 - Suitable inside roadless 0.15 -1.90 - -3.18 -9.71 0.03 - -3.12 -0.03 - Total suitable 2.86 -12.30 - -5.13 -38.51 -0.26 4.67 -3.07 0.24 - Inventoried roadless 2.91 -35.19 0.13 -12.36 -52.39 -2.33 1.61 -4.81 -0.98 0.07 Designated wilderness -2.41 -64.61 0.02 -29.18 -27.40 - 0.00 -26.92 0.21 0.03 Other 3.55 3.31 0.68 -5.00 -17.44 - 1.90 -0.27 0.15 0.05 Total not suitable 4.05 -96.49 0.84 -46.54 -97.22 -2.33 3.50 -32.00 -0.63 0.15
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 73

Figure 39—Tree ages for junipers that occur on juniper forest types, and junipers that occur on other forest types (primarily Douglas-fir 

and ponderosa pine). 
74 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Conclusions

Wyoming’s 10.5 million acres of forest land encompasses a large array of 

ecosystems, forest types, and species, with a relatively diverse mixture of coniferous and deciduous tree species. The major forest-type groups in Wyoming by order of abundance are Fir/spruce/mountain hemlock, Lodgepole pine (which occur 

primarily in the Southern Rocky Mountain Steppe (M331) ecoregion province), 

followed by the Pinyon/juniper forest-type group, which occur primarily in the 

Intermountain Semi-Desert Province (342) ecoregion (fig. 1; table B4). 

Of the forested area in Wyoming, the vast majority (82 percent) is administered by Federal agencies (table B2). Nearly 56 percent of Wyoming forest land 

is controlled by National Forest Systems and 1.5 million acres, and 14 percent is 

owned by private landowners. This large amount of public land indicates a forest 

resource that is managed to meet the diverse needs of the people of Wyoming. 

These needs include wildlife, water quality, recreation, pollution control, and timber products that furnish jobs and strengthen local economies.

The most striking estimates in Wyoming’s forest inventory are the high ratio 

of mortality to growth, causing large reductions in net growth and negative net 

growth in some of the major forest types in the State. Negative net growth was 

recorded Statewide for the Lodgepole pine, Fir/spruce/mountain hemlock, Other 

0 

0.1 

0.2 

0.3 

0.4 

0.5 

0-49 50-99 100-149 150-199 200-249 250-299 300-349 350-399 400-449 

Frequency of tree ages 

Age classes 

Juniper forest types Other forest types 

Figure 40—Frequency distribution of tree ages for juniper that occur in juniper forest types (Rocky Mountain juniper and 

pinyon/juniper) and tree ages for juniper that occur in other forest types (primarily Douglas-fir and ponderosa pine). 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 75

western softwoods, Douglas-fir, and Aspen/birch forest types. The only commercially important softwood to exhibit positive net growth was the Ponderosa pine 

forest type. Per-acre mortality was higher on National Forest Systems lands than 

other ownerships, and in that owner group, mortality was higher on reserved when 

compared to lands in unreserved status. The opposite was true for non-NFS owner 

groups; that is, per-acre mortality was higher on unreserved lands.

Insects and fire are the major contributing factors for the elevated levels 

of mortality over the 2011–2015 period in Wyoming. The peak in the 0–20 year 

stand-age class suggests much of the stand-replacing mortality is resulting in forest 

regeneration. A second peak in the 101–120 year age class suggests there are still 

many aging forests in the State that may become susceptible to insect outbreaks 

over time. Mountain pine beetle, spruce beetle, and Douglas-fir beetle, along with 

the spruce budworm, are important native disturbance agents that are currently 

exhibiting elevated populations in Wyoming. With 5 years of continuous inventory 

data, it is hard to say whether any of these populations are currently an “epidemic.” 

Clearly, mortality attributed to these insects will continue to shape the composition 

and structure of Wyoming’s forests.

Wyoming’s commercial timber harvest volume has continued to increase 

compared to 2010 and 2005 estimates. However, Statewide removals represent 

only about 8 percent of annual gross growth and vary widely by ownership group 

(table 6). For example, private landowners’ removals account for approximately 

21 percent of annual gross growth, whereas removals from national forests account 

for about 8 percent. Removals also vary by geographic area, with the southeast 

portion of the State exhibiting the largest increase in percentage of the harvest, 

from 9.5 in 2010 to 34.7 in 2014. Over the same time period, the western portion 

of the State declined in removals while the northwest remained relatively constant.

Large areas of forest in Wyoming have been deemed unsuitable for harvesting, whether due to administrative or physical barriers. This can have large implications for managing bark beetle infestation, and also for wildlife habitat. For example, there is considerable area of spruce-fir and lodgepole pine forest in the State 

that could be considered snowshoe hare habitat, which is an important prey species 

for Canada lynx. While much of this area will remain protected in the short-term 

from harvesting, as forests grow they mature out of desirable habitat, so that in the 

long-term these same “protected” forests will be off limits to harvesting that could 

create future suitable habitat.

The systematic interpenetrating panel design of the FIA annual inventory 

presents opportunities to assess trends in inventory estimates never before possible 

with previous periodic inventories. Therefore, the information presented in this 

report serves as a baseline and might indicate opportunities for further investigation. Inferences about temporal trends require consideration of independent estimates of the population status each year, each of which uses completely different 

sample plots from different panels. These estimators can be used to track mortality 

events and lead to better monitoring of forest growth and tree harvest activity. 

As the annual plots in Wyoming converge on their full representation in 2020, a 
76 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

complete and representative accounting of the contemporary forest resource will 

be completed. Furthermore, as the annual inventory effort extends into the second 

measurement cycle in Wyoming, the power to detect trends and significant effects 

related to growth, mortality, removals, and other parameters of interest will be 

realized. In this way, the FIA program fills the need for accurate and consistent 

long-term monitoring procedures and data that analysts, managers, and researchers 

can rely on for monitoring forest status and trends and for studying forest dynamics over time.

References

Bechtold, W.A.; Patterson, P.L., eds. 2005. The enhanced Forest Inventory and 

Analysis program—National sampling design and estimation procedures. Gen. 

Tech. Rep. SRS-80. Asheville, NC: U.S. Department of Agriculture, Forest 

Service, Southern Research Station. 85 p.

Berg, N.B.; Gese, E.M.; Squires, J.R.; [et al.]. 2012. Influence of forest structure 

on the abundance of snowshoe hares in Western Wyoming. Journal of Wildlife 

Management. 76: 1480–1488.

Blackard, J.A.; Finco, M.V.; Helmer, E.H.; [et al.]. 2008. Mapping U.S. forest 

biomass using nationwide forest inventory data and moderate resolution information. Remote Sensing of Environment. 112: 1658–1677.

Brickell, J.E. 1970. Equations and computer subroutines for estimating site quality of eight Rocky Mountain species. Res. Pap. INT-75. Ogden, UT: U.S. 

Department of Agriculture, Forest Service, Intermountain Research Station. 

22 p.

Bull, E. L. 2002. The value of coarse woody debris to vertebrates in the Pacific 

Northwest. In: Laudenslayer, W.F., Jr.; Shea, P.J.; Valentine, B.E., eds. Proceedings of the symposium on the ecology and management of dead wood in 

western forests. Gen. Tech. Rep. PSW-GTR-181. Albany, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest Research Station: 171–178.

Choate, G.A. 1963. The forests of Wyoming. Res. Bull. INT-2. Ogden, UT: U.S. 

Department of Agriculture, Forest Service, Intermountain Research Station. 

45 p. + map.

Chojnacky, D.C. 1984. Volume and biomass for curlleaf Cercocarpus in Nevada. 

Res. Pap. INT-332. Ogden, UT: U.S. Department of Agriculture, Forest Service, 

Intermountain Forest and Range Experiment Station. 8 p.

Chojnacky, D.C. 1985. Pinyon-juniper volume equations for the central Rocky 

Mountain States. Res. Note INT-339. Ogden, UT: U.S. Department of 

Agriculture, Forest Service, Intermountain Research Station. 10 p.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 77

Chojnacky, D.C. 1992. Estimating volume and biomass for dryland oak species. 

In: Ecology and management of oak and associated woodlands: Perspectives in 

the southwestern United States and northern Mexico; 1992 April 27–30; Sierra 

Vista, AZ. Gen. Tech. Rep. GTR-RM-218. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment 

Station: 155–161.

Chojnacky, D.C.; Moisen, G.G. 1993. Converting wood volume to biomass 

for pinyon and juniper. Res. Note INT-411. Ogden, UT: U.S. Department of 

Agriculture, Forest Service, Intermountain Research Station. 5 p.

Cleland, D.T.; Avers, P.E.; McNab, W.H.; [et al.]. 1997. National hierarchical 

framework of ecological units. In: Boyce, M.S.; Haney, A., eds. Ecosystem 

management applications for sustainable forest and wildlife resources. New 

Haven, CT: Yale University Press: 181–200.

Cohen, S.; Miller, D. 1978. The big burn: The Northwest’s fire of 1910. Missoula, 

MT: Pictorial Histories Publishing Co. 96 p.

DeBlander, L. 2002. Forest resources of the Black Hills National Forest. Fort 

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

Research Station, 13 p.

Edminster, C.B.; Beeson, R.T.; Metcalf, G.E. 1980. Volume tables and pointsampling factors for ponderosa pine in the Colorado Front Range. Res. Pap. 

RM-218. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Forest and Range Experiment Station. 24 p.

Edminster, C.B.; Mowrer, H.T.; Hinds, T.E. 1982. Volume tables and point-sampling factors for aspen in Colorado. Res. Note RM-232. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Forest and Range 

Experiment Station. 16 p.

Edminster, C.B.; Mowrer, H.T.; Sheppard, W.D. 1985. Site index curves for aspen 

in the central Rocky Mountains. Res. Note: RM-453.Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Forest and Range 

Experiment Station 4 p.

Egan, T. 2009. The big burn: Teddy Roosevelt and the fire that saved America. 

Boston, MA: Houghton Mifflin Harcourt. 324 p.

Energy Information Association (EIA). 2016. U.S. States: State profiles and energy 

estimates. State Energy Data System (SEDS): 1960–2013. [Data files-Consumption-in physical units]. http://www.eia.gov/state/seds/seds-data-complete.

cfm?sid=US#CompleteDataFile.

Eidenshenk, J.; Schwind, B.; Brewer, K.; [et al]. 2007. A project for monitoring 

trends in burn severity. Fire Ecology. Special Issue 3(1).

Fettig, C.J.; Reid, M.L.; Bentz, B.J.; [et al.] 2013. Changing climates, changing 

forests: A Western North American perspective. Journal of Forestry. 111(3): 

214–228.
78 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Field, S.G.; Schoettle, A.W.; Klutsch, J.G.; [et al.]. 2012. Demographic projection 

of high-elevation white pines infected with white pine blister rust: A nonlinear 

disease model. Ecological Applications. 22(1): 166–183.

Gillespie, A.J.R. 1999. Rationale for a national annual forest inventory program. 

Journal of Forestry. 97(12): 16–20.

Goeking, S.A. 2015. Disentangling forest change from forest inventory change: 

A case study from the US Interior West. Journal of Forestry. 113(5): 475–483.

Goeking, S.A.; Patterson, P.L. 2013. Stratifying to reduce bias caused by high 

nonresponse rates: A case study from New Mexico’s forest inventory. Res. 

Note RMRS-RN-59. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station. 22 p.

Goeking, S.A.; Shaw, J.D.; Witt, C.; [et al.]. 2014. New Mexico’s forest resources, 

2008–2012. Resour. Bull. RMRS-RB-18. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station, 144 p.

Green, A.W.; Conner, R.C. 1989. Forests in Wyoming. Resour. Bull. INT-61. 

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

Research Station. 91 p.

Hart, J.H.; Hart, D.L., 2001. Heartrot fungi’s role in creating Picid nesting sites 

in living aspen. In: Sheppard, W.D.; Binkley, D.; Bartos, D.L.; [et al.], eds. 

Sustaining aspen in western landscapes: Symposium proceedings; 2000 

June 13–15; Grand Junction, CO. Proc. RMRS-P-18. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station: 

207–214.

Hessl, A.E.; Graumlich, L.J. 2002. Interactive effects of human activities, herbivory and fire on quaking aspen (Populus tremuloides) age structures in western 

Wyoming. Journal of Biogeography. 29: 889–902.

Hutchins, H.E.; Lanner, R.M. 1982. The central role of Clark’s nutcracker in the 

dispersal and establishment of whitebark pine. Oecologia. 55: 192–201.

Hutto, R.L. 2006. Toward meaningful snag-management guidelines for postfire 

salvage logging in North American conifer forests. Conservation Biology. 20: 

984–993.

Jules, E.S.; Jackson, J.I.; van Mantgem, P.J.; [et al.]. 2016. The relative contributions of disease and insects in the decline of a long-lived tree: A stochastic 

demographic model of whitebark pine (Pinus albicaulis). Forest Ecology and 

Management. 381: 144–156.

Keane, R.E.; Holsinger, L.M.; Mahalovich, M.F.; [et al.]. 2017. Restoring 

whitebark pine ecosystems in the face of climate change. Gen. Tech. Rep. 

RMRS-GTR-361. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station. 123 p.

Keane, R.E.; Tomback, D.F.; Aubry, C.A.; [et al.]. 2012. A range-wide restoration 

strategy for whitebark pine (Pinus albicaulis). Gen. Tech. Rep. RMRS-GTR-279. 

Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 108 p.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 79

Kemp, P.D. 1956. Volume tables. Unpublished report on file at: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station, Interior West 

Forest Inventory and Analysis Program, Ogden, UT.

Lilieholm, R.J.; Long, J.N.; Patla S. 1994. Assessing goshawk nest stand habitat using stand density index. Cooper Ornithological Society. Studies in Avian 

Biology. 16: 18–24.

Long, J.N. 1985. A practical approach to density management. Forest Chronicle. 

61: 23–37.

Long, J.N.; Daniel, T.W. 1990. Assessment of growing stock in uneven-aged 

stands. Western Journal of Applied Forestry. 5: 93–96.

Long, J.N.; Shaw, J.D. 2005. A density management diagram for even-aged ponderosa pine stands. Western Journal of Applied Forestry. 20: 205–215.

Long, J.N.; Smith, F.W. 1984. Relation between size and density in developing stands: A description and possible mechanisms. Forest Ecology and 

Management. 7(3): 191–206.

McCaughey, W.W.; Scott, G.L.; Izlar, D.K. 2009. Whitebark pine planting guidelines. Western Journal of Applied Forestry. 24(3): 163–166.

McClelland, B.R.; Frissell, S.S.; Fischer, W.D.; [et al.]. 1979. Habitat management 

for hole-nesting birds in forests of western larch and Douglas-fir. Journal of 

Forestry. 77: 480–483.

McIver, Chelsea P.; Sorenson, Colin B.; Keegan, Charles E.; [et al.]. 2014. 

Wyoming’s forest products industry and timber harvest, 2010. Resour. Bull. 

RMRS-RB-17. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station. 29 p.

McIver, Chelsea P.; Sorenson, Colin B.; Morgan, Todd A.; [et al.]. [In press]. 

Wyoming’s forest products industry and timber harvest, 2014, Part I: Timber 

harvest, products and flow. Resour. Bull. RMRS-RB-XX. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

McIver, Chelsea P.; Sorenson, Colin B.; Morgan, Todd A.; [et al.]. [In press]. 

Wyoming’s forest products industry and timber harvest, 2014, Part II: Industry 

sectors, capacity and outputs. Resour. Bull. RMRS-RB-XX. Fort Collins, CO: 

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

Station. 

McRoberts, R.E.; Bechtold, W.A.; Patterson, P.L.; [et al.]. 2005. The enhanced 

Forest Inventory and Analysis Program of the USDA Forest Service: Historical 

perspective and announcement of statistical documentation. Journal of Forestry. 

103: 304–308.

Menlove, J. 2008. Forest resources of the Shoshone National Forest. Fort Collins, 

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

Station, 13 p.

Menlove, J.; Shaw, J.D.; Thompson, M.T.; [et al.]. 2012. Montana’s forest resources, 2003–2009. Resour. Bull. RMRS-RB-15. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station. 140 p.
80 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Menlove, J.; Shaw, J.D.; Witt, C.; [et al.]. 2017. Nevada’s forest resources, 2004–

2013. Resour. Bull. RMRS-RB-22. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 167 p.

Meyer, M.D.; Bulaon, B.; MacKenzie, M.; [et al.]. 2016. Mortality, structure, and 

regeneration in whitebark pine stands impacted by mountain pine beetle in the 

southern Sierra Nevada. Canadian Journal of Forest Research. 46: 572–581.

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 State. [Available only on Forest Service intranet: http://apps.fs.fed.us/

Evalidator/evalidator.jsp]. Accessed August 23, 2016.

Mock, C.J. 1996. Climatic controls and spatial variations of precipitation in the 

Western United States. Journal of Climate. 9(5): 1111–1125.

Myers, C.A. 1964. Volume table and point sampling factors for lodgepole pine in 

Colorado and Wyoming. Res. Note RM-6. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment 

Station. 16 p.

Myers, C.A.; Edminster, C.B. 1972. Volume table and point sampling factors for 

Engelmann spruce in Colorado and Wyoming. Res. Note RM-95. Fort Collins, 

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

and Range Experiment Station. 23 p.

Norris, J.R.; Betancourt, J.L.; Jackson, S.T. 2016. Late Holocene expansion of ponderosa pine (Pinus ponderosa) in the Central Rocky Mountains, USA. Journal 

of Biogeography. 43(4): 778–790.

O’Connell, B.M.; LaPoint, E.B.; Turner, J.A.; [et al.]. 2015. The Forest Inventory 

and Analysis Database: Database description and user guide version 6.0.2 for 

Phase 2. U.S. Department of Agriculture, Forest Service. 748 p. https://www.fia.

fs.fed.us/library/database-documentation/index.php.

Oneale, E. 2002. Snag and den tree habitats for wildlife. Habitat Extension Services 

Bulletin 46. Cheyenne, WY: Wyoming Game and Fish Department. 3 p.

Patterson, P.L.; Coulston, J.W.; Roesch, F.A.; [et al.] 2012. A primer for nonresponse in the U.S. forest inventory and analysis program. Environmental 

Monitoring and Assessment. 184(3): 1423–1433.

Pollard, J.E.; Westfall, J.A.; Patterson, P.L.; [et al.]. 2006. Forest inventory and 

analysis national data quality assessment report 2000 to 2003. Gen. Tech. Rep. 

RMRS-GTR-181. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station. 43 p.

Pyne, S.J. 2008. Year of the fires: The story of the great fires of 1910. Revised ed. 

Missoula, MT: Mountain Press Publishing Company. 320 p.

Raffa, K.F.; Aukema, B.H.; Bentz, B.J.; [et al.]. 2008. Cross-scale drivers of natural disturbances prone to anthropogenic amplification: The dynamics of bark 

beetle eruptions. Bioscience. 58(6): 501–517.

Reineke, L.H. 1933. Perfecting a stand density index for even-aged forests. Journal 

of Agricultural Research. 46(7): 627–638.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 81

Reinhardt, E.D.; Keane, R.E.; Calkin, D.E.; [et al.]. 2008. Objectives and considerations for wildland fuel treatment in forested ecosystems of the interior western 

United States. Forest Ecology and Management. 256: 1997–2006.

Ruggiero, L. F.; Aubry, K.B.; Buskirk, S.W.; [et al.]. 2000. Ecology and conservation of lynx in the United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort 

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

Research Station.

Schmid, J.M.; Frye, R.H. 1976. Stand ratings for spruce beetles. Res. Note RM309. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest 

and Range Experiment Station. 4 p.

Schmid, J.M.; Frye, R.H. 1977. Spruce beetle in the Rockies. Gen. Tech. Rep. RM49. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Forest and Range Experiment Station. 38 p.

Shaw, J.D. 2000. Application of stand density index to irregularly structured 

stands. Western Journal of Applied Forestry. 15: 40–42.

Shaw, J.D. 2002. Silvicultural systems for maintenance of structure in a forested 

landscape. Dissertation. Logan, UT: Utah State University.

Shaw, J.D.; Long, J.N. 2007. A density management diagram for longleaf pine 

stands with application to red-cockaded woodpecker habitat. Southern Journal 

of Applied Forestry. 31(1): 28–38.

Shaw J.D.; Steed, B.E.; DeBlander, L.T. 2005. Forest Inventory and Analysis 

(FIA) annual inventory answers the question: What is happening to pinyonjuniper woodlands? Journal of Forestry. 103(6): 280–285.

Smith, B.W. 2002. Forest inventory and analysis: A national inventory and monitoring program. Environmental Pollution. 116: 233–242.

Smith, F.W.; Long, J.N. 1987. Elk hiding and thermal cover guidelines in the context of lodgepole pine stand density. Western Journal of Applied Forestry. 2: 

6–10.

Stage, A.R. 1966. Simultaneous derivation of site-curve and productivity rating 

procedures. In: Society of American Foresters proceedings, 1966. [Original 

equations were reformulated by J. Shaw; documentation on file at U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station, 

Inventory Monitoring, Ogden, UT.] Bethesda, MD: Society of American 

Foresters: 134–136. 

Steed, J. 2008. Forest resources of the Medicine Bow National Forest. Fort Collins, 

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

Station, 13 p.

Thomas, J.W.; Anderson, R.G.; Maser, C.; [et al.]. 1979. Snags. In: Thomas, 

J.W., ed. Wildlife habitats in managed forests: The Blue Mountains of Oregon 

and Washington. Agric. Handb. 553. Washington, DC: U.S. Department of 

Agriculture, Forest Service: 60–77.
82 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Thompson, M.T. 2009. Analysis of conifer mortality in Colorado using Forest 

Inventory and Analysis’s annual forest inventory. Western Journal of Applied 

Forestry. 24(4): 193–197.

Thompson, M.T.; DeBlander, L.T; Blackard, J.A. 2005. Wyoming’s Forests, 2002. 

Resour. Bull. RMRS-RB-6. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station. 156 p.

Thompson, M.T.; Duda, J.A.; DeBlander, L.T.; [et al.]. 2010. Colorado’s forest 

resources, 2002–2006. Resour. Bull. RMRS-RB-11. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

108 p.

Thompson, M.T.; Shaw, J.D.; Witt, C.; [et al.]. 2017. Colorado’s forest resources, 

2004–2013. Resour. Bull. RMRS-RB-23. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 136 p.

USDA Forest Service [USFS]. 2011. Interior West Forest Inventory and Analysis 

Forest Survey field procedures, Ver. 5.0. Washington, DC: U.S. Department of 

Agriculture, Forest Service. http://www.fs.fed.us/rm/ogden/data-collection/

pdf/iwfia_p2_50.pdf; last accessed June 2013.

USDA Forest Service [USFS]. 2013. Interior West Forest Inventory and Analysis 

Forest Survey field procedures, Ver. 6.0. Washington, DC: U.S. Department of 

Agriculture, Forest Service. http://www.fs.fed.us/rm/ogden/data-collection/pdf/

iwfia_p2_60.pdf; last accessed August 2015.

USDA Forest Service [USFS]. 2016. FIA data and tools. Washington, DC: U.S. 

Department of Agriculture, Forest Service. https://www.fia.fs.fed.us/tools-data/

index.php.

U.S. Fish and Wildlife Service (USFWS). 2000. Endangered and threatened 

wildlife and plants; Determination of threatened status for the contiguous 

U.S. distinct population segment of the Canada lynx and related rule. Federal 

Register. 65(58): 16051–16086.

U.S. Fish and Wildlife Service (USFWS). 2011. Endangered and threatened wildlife 

and plants; 12-month finding on a petition to list Pinus albicaulis as endangered 

or threatened with critical habitat. Federal Register. 76(138): 42631–42654.

Van Hooser, D.; Chojnacky, D.C. 1983. Whole tree volume estimates for the 

Rocky Mountain States. Resour. Bull. INT-29. Ogden, UT: U.S. Department of 

Agriculture, Forest Service, Intermountain Research Station. 69 p.

Werstak, C.E., Jr.; Shaw, J.D.; Goeking, S.A.; [et al.]. 2016. Utah’s forest resources, 2003–2012. Resour. Bull. RMRS-RB-20. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station. 159 p.

Wilson, M.J.; Deblander, L.T.; Halverson, K.A. 2010. Resource impacts of the 

1910 fires: A Forest Inventory and Analysis (FIA) perspective. Powerpoint presentation given at: 1910 Fires: A Century Later. Wallace, Idaho, May 20–22, 

2010. Unpublished document on file at: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Forestry Sciences Laboratory, 

Ogden, UT.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 83

Witt, C. 2008. Forest resources of the Bighorn National Forest. Fort Collins, CO: 

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

Station. 13 p.

Witt, C.; Shaw, J.D.; Thompson, M.T.; [et al.]. 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.

Worrall, J.J.; Egeland, L.; Eager, T.; [et al.]. 2008. Rapid mortality of Populus 

tremuloides in southwestern Colorado, USA. Forest Ecology and Management. 

255(3-4): 686–696.
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Appendix A: Standard Forest Inventory and Analysis Terminology

Average annual mortality—The average annual volume of trees 5.0 inches d.b.h./d.r.c. 

and larger that died from natural causes.

Average annual net growth—Average annual net change in volume of trees 5.0 inches 

d.b.h./d.r.c. and larger in the absence of cutting (average annual gross growth minus average annual mortality).

Basal area—The cross-sectional area of a tree stem/bole (trunk) at the point where 

diameter is measured, inclusive of bark. Basal area is calculated for trees 1.0 inch 

and larger in diameter, and is expressed in square feet. For timber species, the calculation is based on diameter at breast height (d.b.h.); for woodland species, it is 

based on diameter at root collar (d.r.c.).

Biomass—The quantity of wood fiber, for trees 1.0 inch d.b.h./d.r.c. and larger, expressed in terms of oven-dry weight. It includes aboveground portions of trees: 

bole/stem (trunk), bark, and branches. Biomass estimates can be computed for live 

and/or dead trees.

Board-foot volume—A unit of measure indicating the amount of wood contained in 

an unfinished board 1 foot wide, 1 foot long, and 1 inch thick. Board-foot volume is computed for the sawlog portion of a sawtimber-size tree; the sawlog portion includes the part of the bole on sawtimber-size tree from a 1-foot stump to a 

minimum sawlog top of 7 inches diameter outside bark (d.o.b.) for softwoods, or 

9 inches d.o.b. for hardwoods. Net board-foot volume is calculated as the gross 

board-foot volume in the sawlog portion of a sawtimber-size tree, less deductions 

for cull (note: board-foot cull deductions are limited to rotten/missing material and 

form defect—referred to as the merchantability factor—board-foot). Board-foot 

volume estimates are computed in both Scribner and International 1⁄4-inch rule, and 

can be calculated for live and/or dead (standing or down) trees.

Census water—Streams, sloughs, estuaries, canals, and other moving bodies of water 

200 feet wide and greater, and lakes, reservoirs, ponds, and other permanent bodies 

of water 4.5 acres in area and greater.

Coarse woody debris—Down pieces of wood leaning more than 45 degrees from vertical with a diameter of at least 3.0 inches and a length of at least 3.0 feet.

Condition class—The combination of discrete landscape and forest attributes that identify, define, and stratify the area associated with a plot. Such attributes include: 

reserved status; owner group; forest type; stand-size class; stand origin, and; tree 

density.

Crown class—A classification of trees based on dominance in relation to adjacent trees 

in the stand as indicated by crown development and amount of sunlight received 

from above and the sides.

Crown cover (Canopy cover)—The percentage of the ground surface area covered by 

a vertical projection of plant crowns. Tree crown cover for a sample site includes 

the combined cover of timber and woodland trees 1.0 inch d.b.h./d.r.c. and larger. 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 85

Maximum crown cover for a site is 100 percent; overlapping cover is not double 

counted.

Cubic-foot volume (merchantable)—A unit of measure indicating the amount of wood 

contained in a cube 1 by 1 by 1 foot. Cubic-foot volume is computed for the merchantable portion of timber and woodland species; the merchantable portion for 

timber species includes that part of a bole from a 1-foot stump to a minimum 

4-inch top d.o.b, or above the place(s) of diameter measurement for any woodland 

tree with a single 5.0-inch stem or larger or a cumulative (calculated) d.r.c. of at 

least 5.0 inches to the 1.5-inch ends of all branches. Net cubic-foot volume is calculated as the gross cubic-foot volume in the merchantable portion of a tree, less 

deductions for cull.

Diameter at breast height (d.b.h.)—The diameter of a tree bole/stem (trunk) measured 

at breast height (4.5 feet aboveground), measured outside the bark. The point of 

diameter measurement may vary for abnormally formed trees.

Diameter at root collar (d.r.c.)—The diameter of a tree stem(s) measured at root collar or at the point nearest the ground line (whichever is higher) that represents 

the basal area of the tree, measured outside the bark. For multi-stemmed trees, 

d.r.c. is calculated from an equation that incorporates the individual stem diameter 

measurements. The point of diameter measurement may vary for woodland trees 

with stems that are abnormally formed. With the exception of seedlings, woodland 

stems qualifying for measurement must be at least 1.0 inch in diameter or larger 

and at least 1.0 foot in length.

Diameter class—A grouping of tree diameters (d.b.h. or d.r.c.) into classes of a specified range. For some diameter classes, the number referenced (e.g., 4”, 6”, 8”) is 

designated as the midpoint of an individual class range. For example, if 2-inch 

classes are specified (the range for an individual class) and even numbers are referenced, the 6-inch class would include trees 5.0- to 6.9-inches in diameter.

Diameter outside bark (d.o.b.)—Tree diameter measurement inclusive of the outside 

perimeter of the tree bark. The d.o.b. measurement may be taken at various points 

on a tree (e.g., breast height, tree top) or log, and is sometimes estimated.

Field plot/location—A reference to the sample site or plot; an area containing the field 

location center and all sample points. A field location consists of four subplots and 

four microplots.

• Subplot—A 1/24-acre fixed-radius area (24-foot horizontal radius) used to sample trees 5.0 inches d.b.h./d.r.c. and larger and understory vegetation.

• Microplot—A 1/300-acre fixed-radius plot (6.8-foot radius), located at the center 

of each subplot, used to inventory seedlings and saplings.

Fixed-radius plot—A circular sample plot of a specified horizontal radius: 1/300 acre = 

6.8-foot radius (microplot); 1/24 acre = 24.0-foot radius (subplot).

Forest industry land—Land owned by a company or an individual(s) operating a primary wood-processing plant.
86 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Forest land—Land that has at least 10 percent cover of live tally tree species of any size, 

or land formerly having such tree cover, and not currently developed for a nonforest use. The minimum area for classification as forest land is 1 acre. Roadside, 

stream-side, and shelterbelt strips of trees must be at least 120 feet wide to qualify 

as forest land. Unimproved roads and trails, streams and other bodies of water, or 

natural clearings in forested areas are classified as forest if less than 120 feet in 

width or 1 acre in size. Grazed woodlands, reverting fields, and pastures that are 

not actively maintained are included if the above qualifications are satisfied.

Forest type—A classification of forest land based on the species forming a plurality of 

live tree stocking.

Gross growth—The annual increase in volume of trees 5.0 inches d.b.h. and larger 

in absence of cutting and mortality. Gross growth includes survivor growth, ingrowth, growth on ingrowth, growth on removals before removal, and growth on 

mortality prior to death.

Growing-stock trees—A live timber species, 5.0 inches d.b.h. or larger, with less than 

2/3 (67 percent) of the merchantable volume cull, and containing at least one solid 

8-foot section, now or prospectively, reasonably free of form defect, on the merchantable portion of the tree.

Growing-stock volume—The cubic-foot volume of sound wood in growing-stock trees 

at least 5.0 inches d.b.h. from a 1-foot stump to a minimum 4-inch top d.o.b. on 

the central stem.

Hardwoods—Dicotyledonous trees, usually broadleaf and deciduous.

Hexagonal grid—A grid in the shape of a hexagon formed from intersecting equilateral 

triangles for the purpose of tessellating the FIA inventory sample. Each hexagon 

in the base grid has an area of 5,937 acres (2,403.6 hectares) and contains one 

inventory plot. The base grid can be subdivided into smaller hexagons to intensify 

the sample.

Indian Trust lands—American Indian lands held in fee, or trust, by the Federal 

Government, but administered for tribal groups or as individual trust allotments.

Inventory year—The year in which a plot was scheduled to be completed. Within each 

subpanel, all plots have the same inventory year. Inventory year may differ from 

measurement year.

Land use—The classification of a land condition by use or type.

Litter—The uppermost layer of organic debris on a forest floor; that is, essentially the 

freshly fallen, or only slightly decomposed material, mainly foliage, but also bark 

fragments, twigs, flowers, fruits, etc. Humus is the organic layer, unrecognizable 

as to origin, immediately beneath the litter layer from which it is derived. Litter 

and humus together are often termed duff.

Logging residue/products—

• Bolt—A short piece of pulpwood; a short log.

• Industrial wood—All commercial roundwood products, excluding fuelwood.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 87

• Logging residue—The unused sections within the merchantable portions of 

sound (growing-stock) trees cut or killed during logging operations.

• Mill or plant residue—Wood material from mills or other primary manufacturing plants that is not used for the mill’s or plant’s primary products. Mill 

or plant residue includes bark, slabs, edgings, trimmings, miscuts, sawdust, 

and shavings. Much of the mill and plant residue is used as fuel and as the 

raw material for such products as pulp, palletized fuel, fiberwood, mulch, 

and animal bedding. Mill or plant residue includes bark and the following 

components:

• Coarse residue—Wood material suitable for chipping, such as slabs, edgings, 

and trim.

• Fine residue—Wood material unsuitable for chipping, such as sawdust and 

shavings.

• Pulpwood—Roundwood, whole-tree chips, or wood residues that are used for 

the production of wood pulp.

• Roundwood—Logs, bolts, or other round sections cut from trees.

Mapped-plot design—A sampling technique that identifies (maps) and separately classifies distinct “conditions” on the field location sample area. Each condition must 

meet minimum size requirements. At the most basic level, condition class delineations include forest land, nonforest land, and water. Forest land conditions can be 

further subdivided into separate condition classes if there are distinct variations in 

forest type, stand size class, stand origin, and stand density, given that each distinct 

area meets minimum size requirements.

Measurement year—The year in which a plot was completed. Measurement year may 

differ from inventory year.

Merchantable portion—For trees measured at d.b.h. and 5.0 inches in d.b.h. and larger, 

the merchantable portion (or “merchantable bole”) includes the part of the tree 

bole from a 1-foot stump to a 4.0-inch top (d.o.b.). For trees measured at d.r.c., 

the merchantable portion includes all qualifying segments above the place(s) of 

diameter measurement for any tree with a single 5.0-inch stem or larger or a cumulative (calculated) d.r.c. of at least 5.0 inches to the 1.5-inch ends of all branches; 

sections below the place(s) of diameter measurement are not included. Qualifying 

segments are stems or branches that are a minimum of 1 foot in length and at least 

1.0 inch in diameter; portions of stems or branches smaller than 1.0 inch in diameter, such as branch tips, are not included in the merchantable portion of the tree.

Mortality tree—All standing or down dead trees 5.0 inches d.b.h./d.r.c. and larger that 

were alive within the previous 5 years (in most States).

National Forest System (NFS) lands—Public lands administered by the Forest Service, 

U.S. Department of Agriculture, such as National Forests, National Grasslands, 

and some National Recreation Areas.

National Park Service (NPS) lands—Public lands administered by the Park Service, 

U.S. Department of the Interior, such as National Parks, National Monuments, 
88 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

National Historic Sites (such as National Memorials and National Battlefields), 

and some National Recreation Areas.

Noncensus water—Portions of rivers, streams, sloughs, estuaries, and canals that are 

30 to 200 feet wide and at least 1 acre in size; and lakes, reservoirs, and ponds 1 to 

4.5 acres in size. Portions of rivers and streams not meeting the criteria for census 

water, but at least 30 feet wide and 1 acre in size, are considered noncensus water. 

Portions of braided streams not meeting the criteria for census water, but at least 

30 feet in width and 1 acre in size, and more than 50 percent water at normal highwater level are also considered noncensus water.

Nonforest land—Land that does not support, or has never supported, forests, and lands 

formerly forested where tree regeneration is precluded by development for other 

uses. Includes areas used for crops, improved pasture, residential areas, city parks, 

improved roads of any width and adjoining rights-of-way, power line clearings of 

any width, and noncensus water. If intermingled in forest areas, unimproved roads 

and nonforest strips must be more than 120 feet wide, and clearings, etc., more 

than 1 acre in size, to qualify as nonforest land.

Nonindustrial private lands—Privately owned land excluding forest industry land.

Nonstocked stand—A formerly stocked stand that currently has less than 10 percent 

stocking, but has the potential to again become 10 percent stocked. For example, 

recently harvested, burned, or windthrow-damaged areas.

Other Federal lands—Public lands administered by Federal agencies other than the 

Forest Service, U.S. Department of Agriculture, or the Bureau of Land Management, 

U.S. Department of the Interior.

Other private lands—Privately owned lands other than forest industry or Indian Trust.

Other public lands—Public lands administered by agencies other than the Forest 

Service, U.S. Department of Agriculture. Includes lands administered by other 

Federal, State, county, and local government agencies, including lands leased by 

these agencies for more than 50 years.

Poletimber-size trees—For trees measured at d.b.h, softwoods 5.0 to 8.9 inches d.b.h. 

and hardwoods 5.0 to 10.9 inches d.b.h. For trees measured at d.r.c., all live trees 

5.0 to 8.9 inches d.r.c.

Primary wood-processing plants—An industrial plant that processes roundwood 

products, such as sawlogs, pulpwood bolts, or veneer logs.

Private lands—All lands not owned or managed by a Federal, State, or other public 

entity, including lands owned by corporations, trusts, or individuals, as well as 

Tribal lands.

Productive forest land—Forest land capable of producing 20 cubic feet per acre per 

year of wood from trees classified as a timber species (see Appendix D) on forest 

land classified as a timber forest type (see Appendix C).

Productivity—The potential yield capability of a stand calculated as a function of site 

index (expressed in terms of cubic-foot growth per acre per year at age of culmination of mean annual increment). Productivity values for forest land provide an 
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 89

indication of biological potential. Timberland stands are classified by the potential 

net annual growth attainable in fully stocked natural stands. For FIA reporting, 

Productivity Class is a variable that groups stand productivity values into categories of a specified range.

Removals—The net volume of sound (growing-stock) trees removed from the inventory 

by harvesting or other cultural operations (such as timber stand improvement), by 

land clearing, or by changes in land use (such as a shift to Wilderness designation).

Reserved land—Land withdrawn from management for production of wood products 

through statute or administrative designation; examples include Wilderness areas 

and National Parks and Monuments.

Sampling error—A statistical term used to describe the accuracy of the inventory estimates. Expressed on a percentage basis in order to enable comparisons between 

the precision of different estimates, sampling errors are computed by dividing the 

estimate into the square root of its variance.

Sapling—A live tree 1.0-4.9-inches d.b.h./d.r.c.

Sawlog portion—The part of the bole of sawtimber-size trees between a 1-foot stump 

and the sawlog top.

Sawlog top—The point on the bole of sawtimber-size trees above which a sawlog cannot be produced. The minimum sawlog top is 7 inches d.o.b. for softwoods, and 9 

inches d.o.b. for hardwoods.

Sawtimber-size trees—Softwoods 9.0 inches d.b.h. and larger and hardwoods 11.0 

inches and larger.

Sawtimber volume—The growing-stock volume in the sawlog portion of sawtimbersize trees in board feet.

Seedlings—Live trees less than 1.0 inch d.b.h./d.r.c.

Site index—A measure of forest potential productivity for a timberland tree/stand. 

Expressed in terms of the expected height (in feet) of trees on the site at an index 

age of 50 (or 80 years for aspen and cottonwood). Calculated from height-to-age 

equations.

Site tree—A tree used to provide an index of site quality. Timber species selected for 

site index calculations must meet specified criteria with regards to age, diameter, 

crown class, and damage.

Snag—A standing, dead tree.

Softwood trees—Coniferous trees, usually evergreen, having needle- or scale-like 

leaves.

Stand—A community of trees that can be distinguished from adjacent communities 

due to similarities and uniformity in tree and site characteristics, such as age-class 

distribution, species composition, spatial arrangement, structure, etc.

Stand density—A relative measure that quantifies the relationship between trees per 

acre, stand basal area, average stand diameter, and stocking of a forested stand.
90 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Stand density index (SDI) —A widely used index developed by Reineke (1933) that 

expresses relative stand density based on a comparison of measured stand values 

with some standard condition; relative stand density is the ratio, proportion, or 

percent of absolute stand density to a reference level defined by some standard 

level of competition. For FIA reporting, the SDI for a site is usually presented as a 

percentage of the maximum SDI for the forest type. Site SDI values are sometimes 

grouped into SDI classes of a specified percentage range. Maximum SDI values 

vary by species and region.

Standing dead tree—A dead tree that is at least 5.0 inches in diameter, has a bole that 

has an unbroken actual length of at least 4.5 feet, and leans less than 45 degrees 

from vertical as measured from the base of the tree to 4.5 feet. Portions of boles on 

dead trees that are broken have greater than 50 percent of the bole unattached to 

the original source of growth (either above or below 4.5 feet), and are considered 

severed and are included in Down Woody Material (DWM) if they otherwise meet 

DWM tally criteria. For western woodland species with multiple stems, a tree is 

considered down if more than 2/3 of the volume is no longer attached or upright. 

For western woodland species with single stems to qualify as a standing dead tally 

tree, dead trees must be at least 5.0 inches in diameter, be at least 1.0 foot in unbroken actual length, and lean less than 45 degrees from vertical.

Stand-size class—A classification of forest land based on the predominant diameter 

size of live trees presently forming the plurality of live tree stocking. Classes are 

defined as follows:

• Sawtimber stand (large-tree stand)—A stand at least 10 percent stocked 

with live trees, in which half or more of the total stocking is from live trees 

5.0 inches or larger in diameter, and with sawtimber (large tree) stocking 

equal to or greater than poletimber (medium tree) stocking.

• Poletimber stand (Medium-tree stand)—A stand at least 10 percent stocked 

with live trees, in which half or more of the total stocking is from live trees 

5.0 inches or larger in diameter, and with poletimber (medium tree) stocking 

exceeding sawtimber (large tree) stocking.

• Sapling/seedling stand—A stand at least 10 percent stocked with live trees, in 

which half or more of the total stocking is from live trees less than 5.0 inches 

in diameter.

• Nonstocked stand—A formerly stocked stand that currently has less than 10 

percent stocking, but has the potential to again become 10 percent stocked. 

For example, recently harvested, burned, or windthrow-damaged areas.

Stockability (Stockability factor)—An estimate of the stocking potential of a given 

site; for example, a stockability factor of 0.8 for a given site indicates that the site 

is capable of supporting only about 80 percent of “normal” stocking as indicated 

by yield tables. Stockability factors (maximum site value of 1.0) are assigned to 

sites based on habitat type/plant associations.

Stocking—An expression of the extent to which growing space is effectively utilized 

by live trees.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 91

Timber species—Tally tree species traditionally used for industrial wood products. 

These include all species of conifers, except pinyon and juniper. Timber species 

are measured at d.b.h.

Timber stand improvement—A term comprising all intermediate cuttings or treatments, such as thinning, pruning, release cutting, girdling, weeding, or poisoning, 

made to improve the composition, health, and growth of the remaining trees in the 

stand.

Timberland—Unreserved forest land capable of producing 20 cubic feet per acre per 

year of wood from trees classified as a timber species (see Appendix D) on forest 

land designated as a timber forest type (see Appendix C).

Unproductive forest land—Forest land not capable of producing 20 cubic feet per acre 

per year of wood from trees classified as a timber species (see Appendix D) on 

forest land designated as a timber forest type and all forest lands designated as a 

woodland forest type (see Appendix C).

Unreserved forest land—Forest land not withdrawn from management for production 

of wood products through statute or administrative designation.

Wilderness area—An area of undeveloped land currently included in the Wilderness 

System, managed to preserve its natural conditions and retain its primeval character and influence.

Woodland species—Tally tree species that are not usually converted into industrial 

wood products. Common uses of woodland trees are fuelwood, fence posts, and 

Christmas trees. These species include pinyon, juniper, mesquite, locust, mountain-mahogany (Cercocarpus spp.), Rocky Mountain maple, bigtooth maple, desert ironwood, and most oaks (note: bur oak and chinkapin oak are classified as 

timber species). Because most woodland trees are extremely variable in form, diameter is measured at d.r.c.
92 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Appendix B: Standard Forest Resource Tables

Table B1—Percentage of plot area by land status.

Table B2—Area of accessible forest land, in thousand acres, by owner class and 

forest land status.

Table B3—Area of forest land, in thousand acres, by forest-type group and productivity class.

Table B4—Area of forest land, in thousand acres, by forest-type group, ownership 

group, and forest land status.

Table B5—Area of forest land, in thousand acres, by forest-type group and standsize class.

Table B6—Area of forest land, in thousand acres, by forest-type group and standage class.

Table B7—Area of forest land, in thousand acres, by forest-type group and stand 

origin.

Table B8—Area of forest land, in thousand acres, by forest-type group and primary disturbance class.

Table B9—Area of timberland, in thousand acres, by forest-type group and standsize class.

Table B10—Number of live trees (at least 1 inch d.b.h./d.r.c.), in thousand trees, 

on forest land by species group and diameter class.

Table B11—Number of growing-stock trees (at least 5.0 inches d.b.h.) on timberland by species group and diameter class.

Table B12—Net volume of live trees (at least 5 inches d.b.h./d.r.c.), in million 

cubic feet, by owner class and forest land status.

Table B13—Net volume of live trees (at least 5 inches d.b.h./d.r.c.), in million 

cubic feet, on forest land by forest-type group and stand-size class.

Table B14—Net volume of live trees (at least 5 inches d.b.h./d.r.c.), in million 

cubic feet, on forest land by species group and ownership group.

Table B15—Net volume of live trees (at least 5 inches d.b.h./d.r.c.), in million 

cubic feet, on forest land by species group and diameter class.

Table B16—Net volume of live trees (at least 5 inches d.b.h./d.r.c.), in million 

cubic feet, on forest land by forest-type group and stand origin.

Table B17—Net volume of growing-stock trees (at least 5 inches d.b.h.), in million cubic feet, on timberland by species group and diameter class.

Table B18—Net volume of growing-stock trees (at least 5 inches d.b.h.), in million cubic feet, on timberland by species group and ownership group.

Table B19—Net volume of sawtimber trees, in million board feet (International 

1/4 inch rule), on timberland by species group and diameter class.

Table B20—Net volume of sawlog portion of sawtimber trees, in million cubic 

feet, on timberland by species group and ownership group.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 93

Table B21—Average annual net growth of live trees (at least 5 inches d.b.h./d.r.c.), 

in million cubic feet, by owner class and forest land status.

Table B22—Average annual net growth of live trees (at least 5 inches d.b.h./d.r.c.), 

in million cubic feet, on forest land by forest-type group and stand-size class.

Table B23—Average annual net growth of live trees (at least 5 inches d.b.h./d.r.c.), 

in million cubic feet, on forest land by species group and ownership group.

Table B24—Average annual net growth of growing-stock trees (at least 5 inches 

d.b.h.), in million cubic feet, on timberland by species group and ownership 

group.

Table B25—Average annual mortality of trees (at least 5 inches d.b.h.), in million 

cubic feet, by owner class and forest land status.

Table 26—Average annual mortality of trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by forest-type group and stand-size class.

Table B27—Average annual mortality of trees (at least 5 inches d.b.h./d.r.c.), in 

million cubic feet, on forest land by species group and ownership group.

Table B28—Average annual mortality of growing-stock trees (at least 5 inches 

d.b.h.), in million cubic feet, on timberland by species group and ownership 

group.

Table B29—Aboveground dry weight live trees (at least 1 inch d.b.h./d.r.c.), in 

thousand dry short tons, by owner class and forest land status.

Table B30—Aboveground dry weight of live trees (at least 1 inch d.b.h./d.r.c.), 

in thousand dry short tons, on forest land by species group and diameter class.

Table B31—Area of forest land, in thousand acres, by inventory unit, county and 

forest land status.

Table B32—Area of forest land, in thousand acres, by inventory unit, county, 

ownership group and forest land status.

Table B33—Area of timberland, in thousand acres, by inventory unit, county and 

stand-size class.

Table B34—Area of timberland, in thousand acres, by inventory unit, county and 

stocking class.

Table B35—Net volume of growing-stock trees (at least 5 inches d.b.h.), in million cubic feet, and sawtimber trees, in million board feet (International 1/4 inch 

rule), on timberland by inventory unit, county, and major species group.

Table B36—Average annual net growth of growing-stock trees (at least 5 inches 

d.b.h.), in million cubic feet, and sawtimber trees, in million board feet (International 1/4 inch rule), on timberland by inventory unit, county, and major species 

group.

Table B37—Sampling errors by inventory unit and county for area of timberland, 

volume, average annual net growth, average annual removals, and average annual mortality on timberland.
94 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Percentage of sample

Accessible forest land

Unreserved forest land

Timberland 8.1

Unproductive 2.8

Total unreserved forest land 10.9

Reserved forest land

Productive 4.8

Unproductive 0.3

Total reserved forest land 5.1

Total accessible forest land 16.0

Nonforest and other areas

Nonforest land 80.8

Water 0.9

Census 0.7

Non-Census 0.2

Total nonforest and other areas 81.6

Non-response

Access denied 1.8

Hazardous conditions 0.4

Other 0.2

Total non-response 2.4

All land 100.0

Land status

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the percentage rounds to less 

than 0.1 percent. Columns and rows may not add to their totals due to rounding.

Table B1—Percentage of plot area by land status, Wyoming, 

2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 95 Owner class Timberland Unproductive Total Productive Unproductive Total Forest Service National forest 3,796 356 4,153 1,565 103 1,668 5,821 National grassland 15.6 12.5 28.1 - - - - - - 28.1 Other Federal National Park Service - - - - - - 1,521.4 95.6 1,617.0 1,617.0 Bureau of Land Management 360.7 744.9 1,105.6 - - - - - - 1,105.6 U.S. Fish and Wildlife Service - - - - - - 9.7 - - 9.7 9.7 Departments of Defense and Energy - - 24.1 24.1 - - - - - - 24.1 Other Federal - - - - - - - - 12.1 12.1 12.1 State and local government State 250.4 106.6 357.0 - - - - - - 357.0 County and Municipal - - - - - - 6.8 - - 6.8 6.8 Private Undifferentiated private 958.0 553.6 1,511.6 - - - - - - 1,511.6 All owners Total 5,380.8 1,798.2 7,179.1 3,103.1 210.6 3,313.8 10,492.8 Unreserved forests Reserved forests All forest land Table B2— All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding. Area of accessible forest land, in thousand acres, by owner class and forest land status, Wyoming, 2011–2015.
96 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Forest-type group 0-19 20-49 50-84 85-119 120-164 165-224 225+ Pinyon / juniper group 1,081.7 - - - - - - - - - - - - 1,081.7 Douglas-fir group 21.6 574.5 154.6 60.7 - - - - - - 811.4 Ponderosa pine group - - 784.6 63.2 - - - - - - - - 847.8 Fir / spruce / mountain hemlock group 14.1 1,368.6 1,389.3 146.6 - - - - - - 2,918.6 Lodgepole pine group 215.1 2,119.6 151.0 23.0 - - - - - - 2,508.7 Other western softwoods group 266.4 303.5 60.9 - - - - - - - - 630.8 Oak / hickory group 19.3 89.1 - - - - - - - - - - 108.4 Elm / ash / cottonwood group 20.6 50.8 9.8 - - - - - - - - 81.1 Aspen / birch group 139.2 371.0 97.3 11.9 - - - - - - 619.4 Woodland hardwoods group 22.6 - - - - - - - - - - - - 22.6 Nonstocked 208.4 566.4 87.5 - - - - - - - - 862.3 All forest-type groups 2,008.8 6,228.1 2,013.7 242.2 - - - - - - 10,492.8 Site-productivity class (cubic feet/acre/year) Total all classes Table B3—Area of accessible forest land, in thousand acres, by forest-type group and productivity class, Wyoming, 2011–2015. All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 97 Other Other Other Other All Timber- forest Timber- forest Timber- forest Timber- forest forest Forest-type group land land land land land land land land land Pinyon / juniper group - - 55.2 - - 629.6 - - 49.9 - - 347.1 1,081.7 Douglas-fir group 442.2 170.6 62.9 45.4 18.2 - - 72.1 - - 811.4 Ponderosa pine group 244.2 - - 65.6 - - 148.1 - - 390.0 - - 847.8 Fir / spruce / mountain hemlock group 1,578.1 793.1 64.9 388.0 13.9 - - 80.6 - - 2,918.6 Lodgepole pine group 951.2 398.8 50.2 1,011.7 13.9 - - 59.1 23.8 2,508.7 Other western softwoods group 103.1 231.4 18.0 102.3 - - 35.5 79.9 60.7 630.8 Oak / hickory group 12.9 - - - - - - 12.9 - - 63.4 19.3 108.4 Elm / ash / cottonwood group - - 11.2 6.3 8.9 - - 13.0 38.7 3.2 81.1 Aspen / birch group 357.0 142.4 41.8 32.4 9.6 3.0 3.1 30.1 619.4 Woodland hardwoods group - - 10.4 - - 12.1 - - - - - - - - 22.6 Nonstocked 123.2 224.2 51.1 177.5 33.9 12.0 171.1 69.4 862.3 All forest-type groups 3,811.8 2,037.2 360.7 2,407.8 250.4 113.4 958.0 553.6 10,492.8 Table B4—Area of accessible forest land, in thousand acres, by forest-type group, ownership group, and land status, Wyoming, 2011–2015. Forest Service Other Federal All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding. State and local government Undifferentiated private
98 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Large Medium Small All size

Forest-type group diameter diameter diameter Nonstocked classes

Pinyon / juniper group 928.4 70.7 82.7 - - 1,081.7

Douglas-fir group 590.9 93.5 127.0 - - 811.4

Ponderosa pine group 713.1 87.7 47.0 - - 847.8

Fir / spruce / mountain hemlock group 1,772.7 513.4 632.5 - - 2,918.6

Lodgepole pine group 907.3 740.7 860.7 - - 2,508.7

Other western softwoods group 213.3 108.0 309.5 - - 630.8

Oak / hickory group 25.6 32.0 50.9 - - 108.4

Elm / ash / cottonwood group 51.8 9.3 20.1 - - 81.1

Aspen / birch group 68.6 178.8 372.0 - - 619.4

Woodland hardwoods group - - 10.4 12.1 - - 22.6

Nonstocked - - - - - - 862.3 862.3

All forest-type groups 5,271.6 1,844.5 2,514.4 862.3 10,492.8

Stand-size class

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less 

than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.

Table B5—Area of accessible forest land, in thousand acres, by forest-type group and stand-size class, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 99 Non- All Forest-type group stocked 1-20 21-40 41-60 61-80 81-100 101-120 121-140 141-160 161-180 181-200 201+ classes Pinyon / juniper group - - 63.8 31.7 43.3 141.8 128.5 113.4 131.8 60.3 75.3 74.3 217.6 1,081.7 Douglas-fir group - - 109.3 17.7 9.2 30.9 172.1 152.9 99.9 70.2 12.1 36.8 100.2 811.4 Ponderosa pine group - - 22.7 15.1 39.4 100.3 205.3 322.6 85.5 47.0 - - 9.9 - - 847.8 Fir / spruce / mountain hemlock group - - 395.2 209.0 54.0 127.5 321.3 531.7 378.3 267.4 169.6 173.1 291.4 2,918.6 Lodgepole pine group - - 601.8 256.4 74.0 187.4 259.2 374.6 278.9 179.6 59.8 60.4 176.7 2,508.7 Other western softwoods group - - 198.4 88.2 21.3 61.6 54.1 45.1 33.0 11.9 12.1 45.5 59.5 630.8 Oak / hickory group - - 50.9 - - - - 19.3 15.9 22.4 - - - - - - - - - - 108.4 Elm / ash / cottonwood group - - 8.9 14.2 12.6 13.0 5.2 12.7 3.2 11.4 - - - - - - 81.1 Aspen / birch group - - 302.8 69.1 25.7 56.5 120.8 27.6 16.7 - - - - - - - - 619.4 Woodland hardwoods group - - - - 12.1 - - - - 10.4 - - - - - - - - - - - - 22.6 Nonstocked 862.3 - - - - - - - - - - - - - - - - - - - - - - 862.3 All forest-type groups 862.3 1,753.8 713.5 279.5 738.3 1,292.9 1,603.0 1,027.3 647.9 328.9 399.9 845.4 10,492.8 Stand-age class (years) Table B6— All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding. Area of accessible forest land, in thousand acres, by forest-type group and stand-age class, Wyoming, 2011–2015.
100 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Natural Artificial All forest

Forest-type group stands regeneration land

Pinyon / juniper group 1,081.7 - - 1,081.7

Douglas-fir group 808.4 3.0 811.4

Ponderosa pine group 847.8 - - 847.8

Fir / spruce / mountain hemlock group 2,906.7 11.9 2,918.6

Lodgepole pine group 2,496.8 11.9 2,508.7

Other western softwoods group 630.8 - - 630.8

Oak / hickory group 108.4 - - 108.4

Elm / ash / cottonwood group 81.1 - - 81.1

Aspen / birch group 609.7 9.7 619.4

Woodland hardwoods group 22.6 - - 22.6

Nonstocked 862.3 - - 862.3

All forest-type groups 10,456.5 36.4 10,492.8

Stand origin

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. 

Columns and rows may not add to their totals due to rounding.

Table B7—Area of accessible forest land, in thousand acres, by forest-type group and 

stand origin, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 101 Wild Domestic All forest Forest-type group None Insects Disease Fire animals animals Weather Vegetation Other Human Geological land Pinyon / juniper group 1,056.7 - - 12.9 12.1 - - - - - - - - - - - - - - 1,081.7 Douglas-fir group 668.5 110.0 12.1 8.9 - - - - - - - - - - 11.9 - - 811.4 Ponderosa pine group 796.1 11.9 13.6 26.2 - - - - - - - - - - - - - - 847.8 Fir / spruce / mountain hemlock group 1,999.7 688.3 105.1 62.7 3.0 - - - - 11.9 3.0 - - 44.9 2,918.6 Lodgepole pine group 2,000.2 363.1 98.2 26.3 - - - - - - 11.8 9.1 - - - - 2,508.7 Other western softwoods group 430.5 129.9 52.5 11.9 - - - - - - - - - - - - 6.0 630.8 Oak / hickory group 92.4 - - - - 12.9 - - 3.2 - - - - - - - - - - 108.4 Elm / ash / cottonwood group 74.8 - - - - - - - - 6.4 - - - - - - - - - - 81.1 Aspen / birch group 433.1 67.3 79.3 36.8 - - - - - - - - - - - - 2.8 619.4 Woodland hardwoods group 22.6 - - - - - - - - - - - - - - - - - - - - 22.6 Nonstocked 553.8 44.8 9.1 248.6 - - 6.0 - - - - - - - - - - 862.3 All forest-type groups 8,128.3 1,415.3 382.8 446.3 3.0 15.6 - - 23.6 12.1 11.9 53.7 10,492.8 Disturbance class Table B8— All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding. Area of forest land. In thousand acres, by forest-type group and primary disturbance class, Wyoming, 2011–2015.
102 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Large Medium Small All size

Forest-type group diameter diameter diameter Nonstocked classes

Douglas-fir group 432.4 93.5 69.5 - - 595.4

Ponderosa pine group 713.1 87.7 47.0 - - 847.8

Fir / spruce / mountain hemlock group 1,037.8 378.1 321.7 - - 1,737.6

Lodgepole pine group 299.8 483.4 291.2 - - 1,074.3

Other western softwoods group 38.8 33.1 129.1 - - 200.9

Oak / hickory group 25.6 12.7 50.9 - - 89.1

Elm / ash / cottonwood group 35.7 9.3 - - - - 44.9

Aspen / birch group 65.3 126.9 219.2 - - 411.4

Nonstocked - - - - - - 379.2 379.2

All forest-type groups 2,648.5 1,224.6 1,128.5 379.2 5,380.8

Stand-size class

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less 

than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.

Table B9—Area of timberland, in thousand acres, by forest-type group and stand-size class, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 103 1.0- 3.0- 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 25.0- 29.0- 33.0- All Species group 2.9 4.9 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 24.9 28.9 32.9 36.9 37.0+ classes Douglas-fir 67,242 42,779 28,588 21,117 15,267 10,545 6,445 4,054 2,819 1,968 2,297 879 147 71 - - 204,219 Ponderosa and Jeffrey pine 70,617 47,417 25,707 23,948 19,298 12,275 9,012 5,219 3,430 2,090 822 391 - - - - - - 220,225 True fir 658,513 247,642 106,762 64,240 36,674 21,229 11,537 6,696 3,804 2,037 1,539 231 76 - - - - 1,160,977 Engelmann and other spruces 201,327 82,904 53,580 35,038 25,749 17,248 12,046 7,164 5,448 4,396 4,195 2,483 777 71 71 452,498 Lodgepole pine 1,041,851 304,316 185,903 131,916 79,471 39,681 17,201 6,783 3,221 1,521 450 146 - - - - - - 1,812,460 Other western softwoods 159,823 67,184 40,497 24,666 12,497 6,963 2,739 1,144 1,453 506 139 146 73 - - - - 317,829 Western woodland softwoods 52,340 32,168 20,933 18,826 14,936 10,292 8,280 5,370 3,908 2,978 3,190 1,088 641 496 142 175,589 2,251,713 824,410 461,970 319,751 203,893 118,231 67,261 36,430 24,082 15,495 12,633 5,364 1,714 639 213 4,343,798 Cottonwood and aspen 139,542 41,542 17,494 17,064 10,137 6,506 1,592 1,096 365 377 153 306 - - - - 71 236,245 Other western hardwoods 24,055 4,788 7,299 3,990 2,131 1,671 604 77 - - - - - - - - - - - - - - 44,615 Western woodland hardwoods 5,857 5,822 824 398 227 76 - - - - - - - - - - - - - - - - - - 13,203 169,454 52,152 25,617 21,452 12,494 8,253 2,196 1,174 365 377 153 306 - - - - 71 294,063 2,421,167 876,563 487,587 341,202 216,387 126,484 69,457 37,603 24,447 15,872 12,786 5,670 1,714 639 284 4,637,861 Western hardwood species groups Other Table B10— All softwoods Hardwood species groups All hardwoods All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the number of trees rounds to less than 1 thousand trees. Columns and rows may not add to their totals due to rounding. Number of live trees (at least 1 inch d.b.h./d.r.c.), in thousand trees, on forest land by species group and diameter class, Wyoming, 2011–2015. Diameter class (inches) Softwood species groups Western softwood species groups Other
104 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 25.0- 29.0- 33.0- All Species group 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 24.9 28.9 32.9 36.9 37.0+ classes Douglas-fir 22,193 17,224 11,438 9,018 4,924 2,808 2,086 1,600 1,940 515 147 71 - - 73,966 Ponderosa and Jeffrey pine 21,189 20,828 17,155 11,747 8,251 4,992 3,212 1,852 751 232 - - - - - - 90,209 True fir 67,205 40,600 24,438 13,445 8,168 4,241 3,011 1,520 1,467 231 76 - - - - 164,402 Engelmann and other spruces 32,520 21,576 16,187 10,066 7,302 4,294 2,860 2,877 2,547 1,701 490 - - - - 102,420 Lodgepole pine 103,436 74,400 38,652 17,747 7,064 2,037 1,013 455 226 - - - - - - - - 245,030 Other western softwoods 14,162 8,105 3,322 1,575 951 645 365 73 72 - - - - - - - - 29,269 260,705 182,732 111,193 63,598 36,660 19,017 12,547 8,377 7,004 2,679 712 71 - - 705,295 Cottonwood and aspen 12,726 11,197 7,032 5,323 1,367 940 220 304 77 230 - - - - 71 39,487 Other western hardwoods 4,674 2,600 1,668 1,145 385 77 - - - - - - - - - - - - - - 10,549 17,400 13,797 8,701 6,468 1,752 1,017 220 304 77 230 - - - - 71 50,036 278,105 196,530 119,894 70,066 38,412 20,034 12,766 8,681 7,080 2,908 712 71 71 755,330 Table B11— All hardwoods All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the number of trees rounds to less than 1 thousand trees. Columns and rows may not add to their totals due to rounding. Number of growing stock trees (at least 5 inches d.b.h.), in thousand trees, on timberland by species group and diameter class, Wyoming, 2011–2015. Diameter class (inches) Softwood species groups Western softwood species groups All softwoods Hardwood species groups Western hardwood species groups
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 105 All Owner class Timberland Unproductive Total Productive Unproductive Total forest land Forest Service National forest 7,113.5 293.2 7,406.7 1,919.6 74.2 1,993.8 9,400.5 National grassland 13.7 5.4 19.1 - - - - - - 19.1 Other Federal National Park Service - - - - - - 2,785.2 83.4 2,868.7 2,868.7 Bureau of Land Management 400.0 292.0 692.0 - - - - - - 692.0 U.S. Fish and Wildlife Service - - - - - - 0.3 - - 0.3 0.3 Departments of Defense and Energy - - 1.8 1.8 - - - - - - 1.8 Other Federal - - - - - - - - 2.4 2.4 2.4 State and local government State 298.2 48.3 346.5 - - - - - - 346.5 County and Municipal - - - - - - 19.6 - - 19.6 19.6 PrivateUndifferentiated private 1,038.7 191.4 1,230.1 - - - - - - 1,230.1 All owners 8,864.1 832.2 9,696.3 4,724.8 160.0 4,884.9 14,581.1 Unreserved forests Reserved forests Table B12— All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding. Net volume of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, by owner class and forest land status, Wyoming, 2011–2015.
106 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Large Medium Small All size

Forest-type group diameter diameter diameter Nonstocked classes

Pinyon / juniper group 442.3 18.2 3.5 - - 464.0

Douglas-fir group 1,371.3 81.4 33.2 - - 1,485.9

Ponderosa pine group 1,019.3 66.7 9.2 - - 1,095.1

Fir / spruce / mountain hemlock group 5,122.6 764.6 288.3 - - 6,175.5

Lodgepole pine group 2,547.6 1,451.4 249.1 - - 4,248.1

Other western softwoods group 221.3 86.9 46.9 - - 355.1

Oak / hickory group 33.6 22.5 8.3 - - 64.4

Elm / ash / cottonwood group 140.2 3.8 1.2 - - 145.2

Aspen / birch group 125.3 264.7 107.0 - - 497.0

Woodland hardwoods group - - 1.4 3.9 - - 5.3

Nonstocked - - - - - - 45.4 45.4

All forest-type groups 11,023.5 2,761.7 750.5 45.4 14,581.1

Stand-size class

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. 

Columns and rows may not add to their totals due to rounding.

Table B13—Net volume of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by forest 

type group and stand-size class, Wyoming, 2011–2015.

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir 1,195.9 193.5 9.1 109.5 1,508.1

Ponderosa and Jeffrey pine 430.9 103.9 201.0 467.7 1,203.5

True fir 2,043.1 415.1 46.1 35.2 2,539.5

Engelmann and other spruces 2,517.5 508.6 - - 108.5 3,134.6

Lodgepole pine 2,556.3 1,931.3 2.7 154.0 4,644.2

Other western softwoods 361.7 141.2 9.5 76.8 589.2

Western woodland softwoods 24.9 221.5 40.7 107.7 394.9

9,130.3 3,515.1 309.1 1,059.5 14,014.0

Cottonwood and aspen 284.3 48.3 41.8 132.7 507.1

Other western hardwoods 2.4 1.8 15.2 37.9 57.4

Western woodland hardwoods 2.6 0.1 - - - - 2.7

289.3 50.2 57.1 170.7 567.1

9,419.6 3,565.3 366.2 1,230.1 14,581.1

Western hardwood species groups

Other

All hardwoods

All species groups 

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic 

feet. Columns and rows may not add to their totals due to rounding.

All softwoods

Hardwood species groups

Table B14—Net volume of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by species group and 

ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

Other
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 107 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 25.0- 29.0- 33.0- All Species group 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 24.9 28.9 32.9 36.9 37.0+ classes Douglas-fir 60 116 161 197 192 155 155 129 184 114 28 16 - - 1,508 Ponderosa and Jeffrey pine 36 101 158 173 206 171 143 118 59 39 - - - - - - 1,204 True fir 236 374 420 404 342 272 192 138 120 27 16 - - - - 2,540 Engelmann and other spruces 105 195 288 321 347 310 309 315 403 336 157 22 27 3,135 Lodgepole pine 555 1,002 1,110 859 537 278 158 99 31 14 - - - - - - 4,644 Other western softwoods 63 109 111 103 56 32 56 31 12 10 7 - - - - 589 Western woodland softwoods 15 26 35 36 43 40 39 37 47 24 22 26 6 395 1,069 1,925 2,282 2,093 1,723 1,258 1,051 867 856 565 230 63 33 14,014 Cottonwood and aspen 29 85 103 105 40 32 12 18 7 25 - - - - 51 507 Other western hardwoods 10 12 11 16 8 2 - - - - - - - - - - - - - - 57 Western woodland hardwoods 1 1 1 0 - - - - - - - - - - - - - - - - - - 3 40 97 115 121 47 34 12 18 7 25 - - - - 51 567 All species groups 1,109 2,022 2,397 2,214 1,770 1,292 1,063 885 863 590 230 63 84 14,581 Western hardwood species groups Other Table B15— All hardwoods All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the volume rounds to less than 1 million cubic feet. Columns and rows may not add to their totals due to rounding. Net volume of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by species group and diameter class, Wyoming, 2011 –2015. Diameter class (inches) Softwood species groups Western softwood species groups Other All softwoods Hardwood species groups
108 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Natural Artificial All forest

Forest-type group stands regeneration land

Pinyon / juniper group 464.0 - - 464.0

Douglas-fir group 1,485.7 0.2 1,485.9

Ponderosa pine group 1,095.1 - - 1,095.1

Fir / spruce / mountain hemlock group 6,175.5 0.1 6,175.5

Lodgepole pine group 4,246.7 1.4 4,248.1

Other western softwoods group 355.1 - - 355.1

Oak / hickory group 64.4 - - 64.4

Elm / ash / cottonwood group 145.2 - - 145.2

Aspen / birch group 496.6 0.3 497.0

Woodland hardwoods group 5.3 - - 5.3

Nonstocked 45.4 - - 45.4

All forest-type groups 14,579.1 2.0 14,581.1

Stand origin

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. 

Columns and rows may not add to their totals due to rounding.

Table B16—Net volume of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic 

feet, on forest land by forest type group and stand origin, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 109 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 25.0- 29.0- 33.0- All Species group 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 24.9 28.9 32.9 36.9 37.0+ classes Douglas-fir 48 95 124 170 144 107 109 101 154 68 28 16 - - 1,166 Ponderosa and Jeffrey pine 31 91 144 167 192 166 139 110 54 26 - - - - - - 1,119 True fir 153 246 283 256 244 175 154 107 115 27 16 - - - - 1,775 Engelmann and other spruces 67 125 182 190 210 184 159 212 246 226 96 - - - - 1,896 Lodgepole pine 309 552 528 372 215 82 48 27 17 - - - - - - - - 2,150 Other western softwoods 23 37 33 23 21 18 17 2 6 - - - - - - - - 180 631 1,147 1,293 1,178 1,025 733 625 559 593 347 141 16 - - 8,287 Cottonwood and aspen 23 59 76 90 35 29 6 15 3 18 - - - - 51 405 Other western hardwoods 7 8 9 13 5 2 - - - - - - - - - - - - - - 42 30 67 85 103 40 31 6 15 3 18 - - - - 51 448 661 1,214 1,378 1,281 1,065 763 631 574 596 365 141 16 51 8,735 Table B17— All hardwoods All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the volume rounds to less than 1 million cubic feet. Columns and rows may not add to their totals due to rounding. Net volume of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, on timberland by species group and diameter class, Wyoming, 2011–2015. Diameter class (inches) Softwood species groups Western softwood species groups All softwoods Hardwood species groups Western hardwood species groups
110 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Forest Other State and local Undifferentiated All Species group Service Federal government private owners Douglas-fir 976.5 71.6 8.5 109.5 1,166.1 Ponderosa and Jeffrey pine 421.4 65.9 200.1 432.0 1,119.3 True fir 1,597.5 97.7 46.0 33.7 1,774.9 Engelmann and other spruces 1,794.3 5.5 - - 96.6 1,896.3 Lodgepole pine 1,910.2 91.6 2.7 145.5 2,150.0 Other western softwoods 115.4 21.1 1.1 42.6 180.2 6,815.2 353.4 258.3 859.9 8,286.9 Cottonwood and aspen 237.7 33.6 20.6 113.6 405.5 Other western hardwoods 2.0 0.9 10.8 28.7 42.5 239.8 34.5 31.4 142.3 447.9 7,055.0 387.9 289.7 1,002.2 8,734.9 Table B18— All hardwoods All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding. Net volume of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, on timberland by species group and ownership group, Wyoming, 2011–2015. Ownership group Softwood species groups Western softwood species groups All softwoods Hardwood species groups Western hardwood species groups
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 111 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 25.0- 29.0- 33.0- All Species group 10.9 12.9 14.9 16.9 18.9 20.9 24.9 28.9 32.9 36.9 37.0+ classes Douglas-fir 495 805 739 567 593 562 868 419 160 101 - - 5,309 Ponderosa and Jeffrey pine 372 662 914 871 751 627 291 154 - - - - - - 4,641 True fir 1,168 1,232 1,257 921 835 607 670 165 104 - - - - 6,960 Engelmann and other spruces 750 922 1,083 993 875 1,213 1,456 1,381 618 - - - - 9,292 Lodgepole pine 1,998 1,658 1,073 434 252 145 94 - - - - - - - - 5,654 Other western softwoods 105 86 89 77 85 5 32 - - - - - - - - 478 4,887 5,363 5,156 3,863 3,392 3,159 3,412 2,119 882 101 - - 32,334 Cottonwood and aspen - - 429 185 148 27 74 15 82 - - - - 251 1,210 Other western hardwoods - - 17 8 2 - - - - - - - - - - - - - - 27 - - 446 193 150 27 74 15 82 - - - - 251 1,237 4,887 5,809 5,349 4,013 3,418 3,232 3,426 2,201 882 101 251 33,570 Table B19— All hardwoods All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the volume rounds to less than 1 million board feet. Columns and rows may not add to their totals due to rounding. Net volume of sawtimber trees, in million board feet (International 1/4 inch rule), on timberland by species group and diameter class, Wyoming, 2011–2015. Diameter class (inches) Softwood species groups Western softwood species groups All softwoods Hardwood species groups Western hardwood species groups
112 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir 778.2 54.7 6.4 74.3 913.6

Ponderosa and Jeffrey pine 337.1 54.0 158.8 313.3 863.2

True fir 1,090.0 63.6 28.6 25.7 1,207.9

Engelmann and other spruces 1,450.0 3.6 - - 73.5 1,527.0

Lodgepole pine 1,071.4 52.9 - - 48.7 1,173.1

Other western softwoods 63.9 13.6 0.7 32.4 110.5

4,790.6 242.4 194.5 567.8 5,795.3

Cottonwood and aspen 83.9 8.5 14.9 89.6 196.9

Other western hardwoods 0.4 - - 4.9 9.3 14.6

84.4 8.5 19.8 98.9 211.6

4,874.9 250.9 214.2 666.7 6,006.8

All hardwoods

All species groups 

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million 

cubic feet. Columns and rows may not add to their totals due to rounding.

Table B20—Net volume of sawlog portion of sawtimber trees, in million cubic feet, on timberland by species group and 

ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

All softwoods

Hardwood species groups

Western hardwood species groups
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 113 All Owner class Timberland Unproductive Total Productive Unproductive Total forest land Forest Service National forest -154.2 -5.6 -159.8 -144.5 -5.6 -150.1 -310.0 National grassland 0.4 0.1 0.4 - - - - - - 0.4 Other Federal National Park Service - - - - - - 7.7 1.4 9.1 9.1 Bureau of Land Management -5.8 -0.4 -6.2 - - - - - - -6.2 U.S. Fish and Wildlife Service - - - - - - 0.0 - - 0.0 0.0 Departments of Defense and Energy - - -1.1 -1.1 - - - - - - -1.1 Other Federal - - - - - - - - 0.0 0.0 0.0 State and local government State 0.2 0.3 0.5 - - - - - - 0.5 County and Municipal - - - - - - 0.9 - - 0.9 0.9 PrivateUndifferentiated private 3.0 -4.7 -1.7 - - - - - - -1.7 All owners -156.5 -11.3 -167.8 -135.9 -4.2 -140.1 -307.9 Table B21—Average annual net growth of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, by owner class and forest land status, Wyoming, 2011–2015. Unreserved forests Reserved forests All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.
114 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Large Medium Small All size Forest-type group diameter diameter diameter Nonstocked classes Pinyon / juniper group 1.4 -0.8 -0.4 - - 0.2 Douglas-fir group -2.0 -3.6 -12.0 - - -17.6 Ponderosa pine group 13.7 2.2 0.2 - - 16.1 Fir / spruce / mountain hemlock group -65.7 -43.4 -60.6 - - -169.6 Lodgepole pine group -9.9 -18.3 -13.9 - - -42.1 Other western softwoods group -7.5 -2.4 -13.1 - - -23.1 Oak / hickory group 0.6 0.3 0.1 - - 0.9 Elm / ash / cottonwood group 2.9 0.1 0.0 - - 3.1 Aspen / birch group -2.7 0.3 -9.0 - - -11.3 Woodland hardwoods group - - 0.0 0.1 - - 0.1 Nonstocked - - - - - - -64.5 -64.5 All forest-type groups -69.2 -65.7 -108.5 -64.5 -307.9 Table B22—Average annual net growth of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by forest-type group and stand-size class, Wyoming, 2011–2015. Stand-size class All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 115

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir -31.9 1.9 -0.7 -1.5 -32.3

Ponderosa and Jeffrey pine 8.2 -2.1 1.0 5.5 12.6

True fir 6.8 3.0 0.5 1.0 11.3

Engelmann and other spruces -106.1 5.5 - - -1.5 -102.1

Lodgepole pine -126.0 -0.9 0.0 0.8 -126.1

Other western softwoods -60.4 -5.9 -0.1 -8.0 -74.4

Western woodland softwoods 0.2 0.7 0.2 0.3 1.4

-309.3 2.3 1.0 -3.4 -309.5

Cottonwood and aspen -0.2 -0.5 0.1 1.1 0.5

Other western hardwoods 0.0 0.1 0.3 0.6 1.1

Western woodland hardwoods 0.0 0.0 - - - - 0.0

-0.2 -0.4 0.5 1.7 1.5

-309.5 1.8 1.4 -1.7 -307.9

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less 

than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.

Table B23—Average annual net growth of all live trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by 

species group and ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

Other

All softwoods

Hardwood species groups

Western hardwood species groups

Other

All hardwoods

All species groups 

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir -5.4 1.2 -0.7 -1.5 -6.4

Ponderosa and Jeffrey pine 7.8 -0.9 1.0 5.3 13.2

True fir 8.8 -1.0 0.5 1.1 9.3

Engelmann and other spruces -41.2 0.0 - - -1.6 -42.8

Lodgepole pine -94.9 -5.1 0.0 3.2 -96.8

Other western softwoods -28.2 -0.3 -0.2 -5.5 -34.2

-153.0 -6.2 0.6 0.9 -157.7

Cottonwood and aspen -0.5 0.1 -0.8 1.6 0.5

Other western hardwoods 0.0 0.1 0.2 0.4 0.7

-0.4 0.2 -0.6 2.1 1.2

-153.5 -6.0 0.0 3.0 -156.5

Western hardwood species groups

All hardwoods

All species groups 

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less 

than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.

Table B24—Average annual net growth of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, on timberland by 

species group and ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

All softwoods

Hardwood species groups
116 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

All

Owner class Timberland Unproductive Total Productive Unproductive Total forest land

Forest Service

National forest 292.0 10.5 302.5 179.0 7.3 186.3 488.8

National grassland - - 0.0 0.0 - - - - - - 0.0

Other Federal

National Park Service - - - - - - 39.3 0.2 39.5 39.5

Bureau of Land Management 14.3 3.2 17.5 - - - - - - 17.5

U.S. Fish and Wildlife Service - - - - - - 0.0 - - 0.0 0.0

Departments of Defense and Energy - - 1.1 1.1 - - - - - - 1.1

State and local government

State 5.9 0.2 6.1 - - - - - - 6.1

Private

Undifferentiated private 18.2 7.1 25.3 - - - - - - 25.3

All owners 330.4 22.0 352.5 218.4 7.5 225.8 578.3

Unreserved forests Reserved forests

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic 

feet. Columns and rows may not add to their totals due to rounding.

Table B25—Average annual mortality of trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by owner class and forest land status, 

Wyoming, 2011–2015.

Large Medium Small All size

Forest-type group diameter diameter diameter Nonstocked classes

Pinyon / juniper group 2.4 1.1 0.5 - - 3.9

Douglas-fir group 22.9 5.1 12.9 - - 40.9

Ponderosa pine group 6.0 0.3 0.1 - - 6.4

Fir / spruce / mountain hemlock group 150.4 64.5 68.0 - - 282.9

Lodgepole pine group 47.2 51.5 24.4 - - 123.1

Other western softwoods group 10.6 5.3 14.6 - - 30.5

Oak / hickory group 0.2 0.2 0.4 - - 0.8

Elm / ash / cottonwood group 0.0 - - 0.0 - - 0.0

Aspen / birch group 5.8 6.5 11.9 - - 24.2

Woodland hardwoods group - - 0.0 - - - - 0.0

Nonstocked - - - - - - 65.6 65.6

All forest-type groups 245.4 134.4 132.9 65.6 578.3

Stand-size class

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic feet. 

Columns and rows may not add to their totals due to rounding.

Table B26—Average annual mortality of trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on 

forest land by forest-type group and stand-size class,Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 117

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir 51.2 0.2 0.8 3.0 55.2

Ponderosa and Jeffrey pine 1.5 3.5 2.2 5.3 12.5

True fir 41.6 8.7 1.3 0.1 51.7

Engelmann and other spruces 146.4 3.7 - - 2.7 152.9

Lodgepole pine 175.0 31.3 0.3 3.3 210.0

Other western softwoods 66.5 8.5 0.4 8.9 84.2

Western woodland softwoods 0.0 0.7 - - 0.6 1.3

482.2 56.7 5.0 23.8 567.8

Cottonwood and aspen 6.5 1.4 1.0 1.2 10.1

Other western hardwoods 0.0 - - - - 0.3 0.4

Western woodland hardwoods 0.0 - - - - - - 0.0

6.6 1.4 1.0 1.5 10.5

488.8 58.1 6.1 25.3 578.3

Western hardwood species groups

Other

All hardwoods

All species groups 

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less 

than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.

All softwoods

Hardwood species groups

Table B27—Average annual mortality of trees (at least 5 inches d.b.h./d.r.c.), in million cubic feet, on forest land by species 

group and ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

Other
118 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Forest Other State and local Undifferentiated All

Species group Service Federal government private owners

Douglas-fir 21.1 - - 0.8 3.0 24.9

Ponderosa and Jeffrey pine 1.5 1.9 2.2 4.9 10.4

True fir 28.5 3.9 1.3 - - 33.7

Engelmann and other spruces 70.7 0.2 - - 2.6 73.4

Lodgepole pine 132.7 7.2 0.3 0.7 140.9

Other western softwoods 30.2 0.7 0.2 5.9 37.1

284.7 13.8 4.9 17.1 320.4

Cottonwood and aspen 5.7 0.4 1.0 0.2 7.4

Other western hardwoods 0.0 - - - - 0.2 0.3

5.7 0.4 1.0 0.5 7.7

290.4 14.2 5.9 17.6 328.1

All hardwoods

All species groups 

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less 

than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding.

Table B28—Average annual mortality of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, on 

timberland by species group and ownership group, Wyoming, 2011–2015.

Ownership group

Softwood species groups

Western softwood species groups

All softwoods

Hardwood species groups

Western hardwood species groups
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 119

All

Owner class Timberland Unproductive Total Productive Unproductive Total forest land

Forest Service

National forest 122,444 5,681 128,125 32,532 1,619 34,152 162,276

National grassland 274 96 370 - - - - - - 370

Other Federal

National Park Service - - - - - - 48,042 1,749 49,791 49,791

Bureau of Land Management 7,061 5,812 12,873 - - - - - - 12,873

U.S. Fish and Wildlife Service - - - - - - 33 - - 33 33

Departments of Defense and Energy - - 41 41 - - - - - - 41

Other Federal - - - - - - - - 34 34 34

State and local government

State 5,640 954 6,594 - - - - - - 6,594

County and Municipal - - - - - - 343 - - 343 343

Private

Undifferentiated private 19,431 3,748 23,179 - - - - - - 23,179

All owners 154,851 16,331 171,182 80,951 3,402 84,353 255,535

Unreserved forests Reserved forests

All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the aboveground tree biomass rounds to less than 1 thousand dry 

tons. Columns and rows may not add to their totals due to rounding.

Table B29—Aboveground dry weight of all live trees (at least 1 inch d.b.h./d.r.c.), in thousand dry short tons, by owner class and forest land status, 

Wyoming, 2011–2015.
120 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 1.0- 3.0- 5.0- 7.0- 9.0- 11.0- 13.0- 15.0- 17.0- 19.0- 21.0- 23.0- 25.0- 27.0- 29.0+ All Species group 2.9 4.9 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 22.9 24.9 26.9 28.9 classes Douglas-fir 190 734 1,261 2,398 3,276 3,964 3,834 3,081 3,067 2,550 2,039 1,585 1,079 1,165 863 31,086 Ponderosa and Jeffrey pine 109 455 674 1,858 2,858 3,112 3,673 3,031 2,535 2,087 528 505 334 343 - - 22,102 True fir 1,481 3,569 3,432 5,327 5,901 5,619 4,726 3,750 2,630 1,885 826 807 63 297 219 40,531 Engelmann and other spruces 433 1,049 1,625 2,960 4,299 4,751 5,108 4,550 4,503 4,580 3,177 2,663 3,112 1,742 2,969 47,520 Lodgepole pine 2,930 5,769 9,186 16,236 17,751 13,604 8,442 4,350 2,466 1,539 312 170 220 - - - - 82,977 Other western softwoods 221 633 1,213 2,052 2,070 1,890 1,019 581 973 544 93 118 - - 174 111 11,690 Western woodland softwoods 138 286 234 432 586 637 742 679 691 662 645 225 383 68 1,075 7,484 5,502 12,494 17,625 31,263 36,741 33,578 27,544 20,022 16,864 13,848 7,618 6,073 5,191 3,789 5,237 243,390 Cottonwood and aspen 463 794 592 1,595 1,857 1,828 677 543 202 293 113 - - 198 217 810 10,181 Other western hardwoods 93 132 296 336 301 415 187 44 - - - - - - - - - - - - - - 1,804 Western woodland hardwoods 35 77 17 15 11 4 - - - - - - - - - - - - - - - - - - 160 592 1,003 905 1,946 2,169 2,247 864 587 202 293 113 - - 198 217 810 12,145 All species groups 6,093 13,497 18,530 33,209 38,911 35,825 28,408 20,610 17,067 14,141 7,731 6,073 5,389 4,005 6,046 255,535 Western hardwood species groups Other Table B30— All hardwoods All table cells without observations in the inventory sample are indicated by --. Table value of 0 indicates the aboveground tree biomass rounds to less than 1 thousand dry tons. Columns and rows may not add to their totals due to rounding. Aboveground dry weight of all live trees (at least 1 inch d.b.h./d.r.c.), in thousand dry short tons, on forest land by species group and diameter class, Wyoming, 2011–2015. Diameter class (inches) Softwood species groups Western softwood species groups Other All softwoods Hardwood species groups
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 121

All

Timberland Unproductive Total Productive Unproductive Total forest land

Western

Fremont 490.4 337.2 827.6 490.4 337.2 827.6 1,000.6

Hot Springs 54.0 94.9 149.0 54.0 94.9 149.0 161.7

Lincoln 664.2 60.1 724.3 664.2 60.1 724.3 736.8

Park 318.5 148.1 466.6 318.5 148.1 466.6 1,922.7

Sublette 476.4 50.3 526.7 476.4 50.3 526.7 720.5

Sweetwater - - 188.1 188.1 - - 188.1 188.1 188.1

Teton 493.2 11.9 505.0 493.2 11.9 505.0 1,841.9

Uinta 30.9 64.9 95.9 30.9 64.9 95.9 95.9

Total 2,527.5 955.6 3,483.1 2,527.5 955.6 3,483.1 6,668.2

Central and Southeastern

Albany 440.6 105.9 546.5 - - - - - - 546.5

Big Horn 159.5 69.1 228.6 12.9 - - 12.9 241.5

Carbon 599.7 83.1 682.8 48.7 - - 48.7 731.5

Converse 190.1 44.5 234.6 - - - - - - 234.6

Goshen - - 25.1 25.1 - - - - - - 25.1

Johnson 323.5 56.8 380.3 36.4 - - 36.4 416.7

Laramie 32.8 - - 32.8 - - - - - - 32.8

Natrona 39.5 127.4 166.9 - - - - - - 166.9

Niobrara 27.8 12.4 40.2 - - - - - - 40.2

Platte 54.3 54.3 108.6 6.8 12.1 18.8 127.4

Sheridan 306.0 38.3 344.2 11.8 - - 11.8 356.0

Washakie 26.3 85.6 111.9 - - - - - - 111.9

Total 2,200.1 702.4 2,902.5 116.6 12.1 128.7 3,031.2

Northeastern

Campbell 76.5 70.4 146.9 - - - - - - 146.9

Crook 474.6 35.3 509.9 - - - - - - 509.9

Weston 102.1 34.5 136.6 - - - - - - 136.6

Total 653.2 140.2 793.4 - - - - - - 793.4

All counties 5,380.8 1,798.2 7,179.1 3,103.1 210.6 3,313.8 10,492.8

Unreserved forests Reserved forests

Inventory unit and county

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. 

Columns and rows may not add to their totals due to rounding.

Table B31—Area of accessible forest land, in thousand acres, by Forest Survey Unit, county and forest land status, Wyoming, 2011–2015.
122 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Other Other Other Other All

Inventory unit Timber- forest Timber- forest Timber- forest Timber- forest forest

land land land land land land land land land

Western

Fremont 289.2 271.4 53.9 93.0 3.0 - - 144.3 145.8 1,000.6

Hot Springs 12.7 22.2 - - 40.9 - - - - 41.3 44.5 161.7

Lincoln 563.1 52.1 76.0 8.8 - - - - 25.1 11.7 736.8

Park 285.2 741.3 12.1 790.5 18.2 12.0 3.0 60.4 1,922.7

Sublette 436.3 244.1 19.7 - - - - - - 20.4 - - 720.5

Sweetwater - - - - - - 164.6 - - 11.8 - - 11.8 188.1

Teton 493.2 479.2 - - 869.4 - - - - - - - - 1,841.9

Uinta 15.5 - - 12.4 27.8 - - - - 3.1 37.1 95.9

Total 2,095.0 1,810.5 174.1 1,995.1 21.2 23.8 237.2 311.3 6,668.2

Central and Southeastern

Albany 323.5 29.0 - - 12.0 33.6 39.2 83.5 25.6 546.5

Big Horn 137.3 22.1 - - 40.9 - - 12.9 22.1 6.1 241.5

Carbon 508.0 76.6 54.2 31.9 37.4 11.3 - - 12.1 731.5

Converse 51.9 - - 12.4 - - 29.0 6.2 96.9 38.3 234.6

Goshen - - - - - - 12.5 - - - - - - 12.5 25.1

Johnson 186.5 62.9 74.2 30.3 - - - - 62.9 - - 416.7

Laramie - - - - - - - - - - - - 32.8 - - 32.8

Natrona - - - - 15.2 115.3 12.2 - - 12.2 12.2 166.9

Niobrara - - - - - - - - - - - - 27.8 12.4 40.2

Platte - - - - 12.1 36.2 6.0 6.8 36.2 30.2 127.4

Sheridan 282.8 23.6 - - 8.8 - - - - 23.1 17.7 356.0

Washakie 26.3 - - - - 72.4 - - 13.2 - - - - 111.9

Total 1,516.4 214.2 168.1 360.3 118.1 89.6 397.5 167.0 3,031.2

Northeastern

Campbell 3.1 - - 12.2 39.8 12.2 - - 49.0 30.6 146.9

Crook 173.6 - - - - - - 64.3 - - 236.7 35.3 509.9

Weston 23.8 12.5 6.3 12.5 34.5 - - 37.6 9.4 136.6

Total 200.4 12.5 18.5 52.3 111.0 - - 323.3 75.3 793.4

All counties 3,811.8 2,037.2 360.7 2,407.8 250.4 113.4 958.0 553.6 10,492.8

Table B32—Area of accessible forest land, in thousand acres, by Forest Survey Unit, county, ownership group and forest land status, Wyoming, 

2011–2015.

and county

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. 

Columns and rows may not add to their totals due to rounding.

Forest Service Other Federal

State and local Undifferentiated

government private
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 123

Large Medium Small All size

diameter diameter diameter Nonstocked classes

Western

Fremont 163.9 152.3 128.4 45.8 490.4

Hot Springs 25.4 3.2 22.2 3.2 54.0

Lincoln 391.4 92.5 156.0 24.3 664.2

Park 90.9 109.0 94.3 24.2 318.5

Sublette 221.5 87.9 147.4 19.6 476.4

Teton 346.8 20.8 91.9 33.7 493.2

Uinta - - 18.6 12.4 - - 30.9

Total 1,240.0 484.1 652.6 150.7 2,527.5

Central and Southeastern

Albany 147.4 125.8 121.1 46.3 440.6

Big Horn 102.7 21.8 34.9 - - 159.5

Carbon 223.4 228.9 147.4 - - 599.7

Converse 117.8 10.2 - - 62.1 190.1

Johnson 173.0 119.1 25.4 6.1 323.5

Laramie 20.9 - - - - 11.9 32.8

Natrona 15.2 - - 9.1 15.2 39.5

Niobrara 15.5 - - - - 12.4 27.8

Platte 15.1 9.0 12.1 18.1 54.3

Sheridan 149.8 106.0 50.1 - - 306.0

Washakie 13.2 13.2 - - - - 26.3

Total 993.9 634.1 399.9 172.1 2,200.1

Northeastern

Campbell 39.8 - - 12.2 24.5 76.5

Crook 334.0 54.4 63.7 22.5 474.6

Weston 40.8 52.0 - - 9.4 102.1

Total 414.5 106.4 76.0 56.4 653.2

All counties 2,648.5 1,224.6 1,128.5 379.2 5,380.8

Stand-size class

Inventory unit and county

Table B33—Area of timberland, in thousand acres, by Forest Survey Unit, county and stand-size class, 

Wyoming, 2011–2015.

All table cells without observations in the inventory sample are indicated by --. 

Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. 

Columns and rows may not add to their totals due to rounding.
124 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Poorly Moderately Fully OverNonstocked stocked stocked stocked stocked All classes

Western

Fremont 45.8 163.9 208.9 71.7 - - 490.4

Hot Springs 3.2 25.4 12.7 12.7 - - 54.0

Lincoln 24.3 158.6 267.4 205.0 8.8 664.2

Park 24.2 142.8 100.0 51.5 - - 318.5

Sweetwater 19.6 130.1 194.0 115.4 17.3 476.4

Teton 33.7 139.3 219.4 100.8 - - 493.2

Uinta - - 27.8 - - - - 3.1 30.9

Total 150.7 788.0 1,002.4 557.1 29.2 2,527.5

Central and Southeastern

Albany 59.9 175.3 173.0 32.4 - - 440.6

Big Horn - - 34.8 47.8 76.9 - - 159.5

Carbon - - 128.0 237.2 189.6 44.8 599.7

Converse 62.1 59.7 37.3 31.0 - - 190.1

Johnson 6.1 103.4 93.8 108.1 12.1 323.5

Laramie 11.9 20.9 - - - - - - 32.8

Natrona 15.2 12.2 - - 12.2 - - 39.5

Niobrara 12.4 12.4 3.1 - - - - 27.8

Platte 18.1 27.1 9.0 - - - - 54.3

Sheridan - - 73.6 173.4 58.9 - - 306.0

Washakie - - - - - - 26.3 - - 26.3

Total 185.7 647.4 774.6 535.4 56.9 2,200.1

Northeastern

Campbell 24.5 39.8 12.2 - - - - 76.5

Crook 35.4 134.7 260.3 44.3 - - 474.6

Weston 9.4 92.7 - - - - - - 102.1

Total 69.2 267.2 272.5 44.3 - - 653.2

All counties 405.7 1,702.6 2,049.6 1,136.9 86.2 5,380.8

Stocking class of growing-stock trees

Inventory unit and county

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. 

Columns and rows may not add to their totals due to rounding.

Table B34—Area of timberland, in thousand acres, by Forest Survey Unit, county and stocking class, Wyoming, 2011–2015.
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 125 Inventory unit Other Soft Hard All Other Soft Hard All Pine softwoods hardwoods hardwoods species Pine softwoods hardwoods hardwoods species (In million cubic feet) (In million board feet) WesternFremont 185.5 344.8 2.9 - - 533.1 487.2 1,241.4 6.2 - - 1,734.8 Hot Springs 1.6 35.2 33.0 - - 69.8 5.8 136.3 136.4 - - 278.4 Lincoln 234.0 1,273.9 61.9 - - 1,569.8 781.6 6,240.0 98.9 - - 7,120.5 Park 139.4 156.7 2.4 - - 298.5 282.4 577.5 1.0 - - 860.9 Sublette 177.1 706.4 35.1 - - 918.6 522.8 3,613.2 81.5 - - 4,217.5 Teton 171.5 863.3 25.2 - - 1,060.0 611.1 4,267.9 100.4 - - 4,979.4 Uinta 30.5 1.6 11.6 - - 43.7 19.2 - - 19.0 - - 38.2 Total 939.5 3,381.9 172.0 - - 4,493.4 2,710.0 16,076.3 443.5 - - 19,229.8 Central and Southeastern Albany 180.8 190.5 29.2 - - 400.5 447.4 591.6 96.6 - - 1,135.6 Big Horn 148.0 250.7 0.7 - - 399.4 570.1 1,066.8 - - - - 1,636.9 Carbon 235.6 570.6 138.1 - - 944.3 426.1 2,034.0 410.5 - - 2,870.7 Converse 187.5 12.1 1.0 - - 200.6 668.2 33.5 3.2 - - 704.9 Johnson 564.8 119.4 1.9 - - 686.1 1,483.4 498.4 - - - - 1,981.8 Laramie 11.1 - - - - - - 11.1 21.6 - - - - - - 21.6 Natrona 19.2 27.1 0.1 - - 46.4 87.5 111.1 - - - - 198.5 Niobrara 11.2 - - - - - - 11.2 34.9 - - - - - - 34.9 Platte 19.2 - - - - - - 19.2 31.1 - - - - - - 31.1 Sheridan 417.8 168.6 52.5 3.9 642.8 1,178.7 692.5 250.8 1.7 2,123.8 Washakie 2.5 116.4 - - - - 118.9 9.5 456.1 - - - - 465.6 Total 1,797.7 1,455.4 223.5 3.9 3,480.5 4,958.5 5,484.0 761.1 1.7 11,205.4 Northeastern Campbell 32.7 - - - - - - 32.7 119.6 - - - - - - 119.6 Crook 625.4 - - 9.5 37.2 672.0 2,839.7 - - 5.0 25.3 2,870.1 Weston 54.3 - - 1.9 - - 56.1 145.5 - - - - - - 145.5 Total 712.4 - - 11.4 37.2 760.9 3,104.8 - - 5.0 25.3 3,135.2 All counties 3,449.6 4,837.3 406.9 41.0 8,734.9 10,773.4 21,560.3 1,209.6 27.0 33,570.4 Table B35— and county All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic or board feet. Columns and rows may not add to their totals due to rounding. Net volume of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, and sawtimber trees, in million board feet (International 1/4 inch rule), on timberland by Forest Survey Unit, county, and major species group, Wyoming, 2011–2015. Growing stock Sawtimber Major species group Major species group
126 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 Inventory unit Other Soft Hard All Other Soft Hard All Pine softwoods hardwoods hardwoods species Pine softwoods hardwoods hardwoods species (In million cubic feet) (In million board feet) WesternFremont -23.2 -3.8 0.2 - - -26.8 -105.7 -9.2 0.2 - - -114.7 Hot Springs -2.3 -1.1 0.7 - - -2.7 -11.7 -4.9 3.0 - - -13.6 Lincoln -8.1 10.9 -0.1 - - 2.8 -21.9 77.8 10.1 - - 66.0 Park -6.4 -14.7 0.0 - - -21.1 -19.5 -63.7 1.0 - - -82.2 Sublette -27.4 0.9 0.3 - - -26.2 -110.4 22.6 6.7 - - -81.1 Teton -21.1 2.7 -0.2 - - -18.6 -96.6 40.9 0.5 - - -55.3 Uinta -3.1 0.1 0.2 - - -2.8 -8.3 - 0.5 - - -7.9 Total -91.7 -5.0 1.2 - - -95.5 -374.1 63.5 21.9 - - -288.7 Central and Southeastern Albany -14.7 -26.4 0.4 - - -40.7 -46.1 -132.0 1.5 - - -176.7 Big Horn -0.3 -8.3 -0.1 - - -8.7 1.1 -36.6 - - - - -35.6 Carbon -33.8 -2.9 -1.9 - - -38.6 -125.7 10.8 2.2 - - -112.7 Converse 1.8 0.2 0.0 - - 2.0 8.0 2.8 3.2 - - 14.0 Johnson 4.8 0.6 0.0 - - 5.4 34.5 11.1 - - - - 45.6 Laramie -0.9 - - - - - - -0.9 -3.3 - - - - - - -3.3 Natrona -0.6 0.6 0.0 - - 0.0 -2.4 5.2 - - - - 2.7 Niobrara -0.2 - - - - - - -0.2 -0.3 - - - - - - -0.3 Platte 0.3 - - - - - - 0.3 2.2 - - - - 0.0 2.2 Sheridan 4.5 -0.2 0.5 0.1 5.0 32.6 -0.5 2.7 0.1 34.9 Washakie 0.0 1.5 - - - - 1.6 0.2 6.3 - - - - 6.5 Total -39.0 -35.0 -1.1 0.1 -74.9 -99.4 -133.0 9.6 0.1 -222.6 Northeastern Campbell 0.1 - - - - - - 0.1 4.2 - - - - - - 4.2 Crook 11.8 - - 0.4 0.6 12.7 70.5 - - 0.2 2.0 72.6 Weston 1.1 - - 0.1 - 1.1 6.7 - - 0.0 - - 6.7 Total 12.9 - - 0.4 0.6 13.9 81.4 - - 0.2 2.0 83.5 All counties -117.7 -39.9 0.5 0.7 -156.5 -392.1 -69.5 31.7 2.0 -427.8 Table B36 All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to less than 0.1 million cubic or board feet. Columns and rows may not add to their totals due to rounding. —Average annual net growth of growing stock trees (at least 5 inches d.b.h.), in million cubic feet, and sawtimber trees, in million board feet (International 1/4 inch rule), on timberland by Forest Survey Unit, county, and major species group, Wyoming, 2011–2015. Growing stock Sawtimber Major species group Major species group and county
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 127 Inventory unit Forest Timberland area area Volume Growth Removals Mortality Volume Growth Removals Mortality Western Fremont 5.34 11.79 17.64 29.34 - - 21.62 20.59 31.53 - - 23.90 Hot Springs 24.90 46.60 64.99 99.02 - - 72.71 66.22 94.58 - - 74.46 Lincoln 7.74 8.44 12.15 100.00 - - 20.75 13.09 50.16 - - 24.06 Park 3.27 17.69 26.94 40.32 - - 34.69 31.53 43.73 - - 36.80 Sublette 5.73 10.92 19.58 36.93 - - 22.89 23.83 55.93 - - 26.36 Sweetwater 23.66 - - - - - - - - - - - - - - - - - - Teton 2.88 13.40 18.00 51.38 - - 25.24 19.42 84.20 - - 26.57 Uinta 32.75 57.78 53.25 63.70 - - 58.30 57.10 65.37 - - 60.93 Total 2.08 5.26 7.80 19.98 - - 10.97 9.08 31.19 - - 12.14 Central and Southeastern Albany 7.99 9.83 15.02 33.42 - - 28.66 18.92 38.89 - - 32.80 Big Horn 15.16 21.50 26.57 52.38 - - 36.65 28.15 64.39 - - 38.64 Carbon 4.70 6.48 11.06 27.13 - - 16.95 13.82 41.07 - - 19.80 Converse 14.87 16.51 27.02 100.00 - - 55.38 30.64 51.50 - - 44.93 Goshen 70.40 - - - - - - - - - - - - - - - - - - Johnson 10.32 13.72 18.62 47.20 - - 47.27 21.44 45.03 - - 52.18 Laramie 57.81 57.81 69.31 92.21 - - 83.94 77.38 100.00 - - 83.38 Natrona 25.92 53.61 92.10 100.00 - - 100.00 91.28 100.00 - - 100.00 Niobrara 53.36 63.48 68.30 100.00 - - 100.00 78.08 100.00 - - 100.00 Platte 27.23 41.43 51.76 54.84 - - 65.45 59.15 56.15 - - 100.00 Sheridan 7.37 9.62 16.69 52.95 - - 37.42 21.61 42.45 - - 49.35 Washakie 32.29 70.38 71.27 70.90 - - 100.00 74.36 72.30 - - - - Total 3.86 4.63 7.37 24.56 - - 13.24 8.96 40.59 - - 15.84 Northeastern Campbell 25.97 37.28 59.76 100.00 - - 57.85 66.87 66.16 - - 62.18 Crook 7.14 8.55 14.18 19.16 - - 35.03 17.23 18.77 - - 41.14 Weston 27.40 31.91 36.23 73.82 - - 78.61 45.32 39.77 - - 91.36 Total 8.15 9.08 13.06 18.65 - - 29.02 16.11 16.96 - - 33.95 All counties 1.83 3.30 5.10 17.02 - - 8.37 6.19 30.01 - - 9.60 Table B37—Sampling errors (percent) by Forest Survey Unit and county for area of timberland, volume, average annual net growth, average annual removals, and average annual mortality on timberland, Wyoming, 2011–2015. Growing stock (on timberland) Sawtimber (on timberland) and county All table cells without observations in the inventory sample are indicated by --. Sampling errors that exceed 100% are reported as 100%.
128 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Appendix C: Wyoming Forest-Type Groups and Forest Types, 

With Descriptions and Timber (T) or Woodland (W) Designations

Forest-type groups and forest types are usually named for the predominant 

species (or group of species) on the condition. In order to determine the forest type, 

the stocking (site occupancy) of trees is estimated by softwoods and hardwoods. 

If softwoods predominate, then the forest type will be one of the softwood types 

and if hardwoods predominate, then the forest type will be one of the hardwood 

types. Some other special stocking rules apply to individual forest types and are 

described below.

Associate species are defined as those that regularly form the majority of the 

non-predominant species stocking of mixed-species conditions. These descriptions 

are applicable to the current Wyoming inventory. Species importance, including 

predominance in some cases, will vary for other States or inventory years. When 

species are listed, they are in decreasing order of overall forest type stocking.

ASPEN/BIRCH GROUP (T)

Aspen

Predominant species: quaking aspen

Associate species: Engelmann spruce, Douglas-fir, ponderosa pine, blue spruce

Other species: Gambel oak, limber pine, Rocky Mountain juniper, subalpine fir, 

common or two-needle pinyon

DOUGLAS-FIR GROUP (T)

Douglas-fir

Predominant species: Douglas-fir

Associate species: ponderosa pine, quaking aspen, Gambel oak, limber pine, 

Engelmann spruce

Other species: Rocky Mountain juniper, common or two-needle pinyon, blue 

spruce

ELM/ASH/COTTONWOOD GROUP (T)

Cottonwood

Predominant species: Plains cottonwood, narrowleaf cottonwood

Associate species: ponderosa pine, boxelder, green ash

Other species: Rocky Mountain juniper, common or two-needle pinyon

Special rules: Stocking of cottonwoods must be at least 50 percent of total 

stocking.

EXOTIC HARDWOODS GROUP (T)

Other exotic hardwoods

Predominant species: No tree species recorded greater than or equal to 1.0 inches in diameter

Associate species: none identified

Special rules: A “catch-all” type for non-native hardwood species.

FIR/SPRUCE/MOUNTAIN HEMLOCK GROUP (T)
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 129

Blue spruce

Predominant species: blue spruce

Associate species: quaking aspen

Other species: Douglas-fir, Engelmann spruce, Gambel oak

Engelmann spruce

Predominant species: Engelmann spruce

Associate species: subalpine fir, Douglas-fir, quaking aspen

Other species: lodgepole pine, limber pine, whitebark pine

Engelmann spruce/subalpine fir

Predominant species: Engelmann spruce, subalpine fir

Associate species: quaking aspen, Douglas-fir, lodgepole pine,

Other species: whitebark pine, limber pine

Special rules: The combined stocking of Engelmann spruce and subalpine fir is 

predominant. Stocking of both Engelmann spruce and subalpine fir must 

each be between 5 and 74 percent of the total.

Subalpine fir

Predominant species: subalpine fir

Associate species: Douglas-fir, Engelmann spruce, limber pine, lodgepole pine, 

whitebark pine

LODGEPOLE PINE

Lodgepole pine

Predominant species: lodgepole pine

Associate species: quaking aspen, subalpine fir, Engelmann spruce, Douglas-fir

Other species: whitebark pine, limber pine

NONSTOCKED

Nonstocked

Predominant species: various, but many nonstocked conditions have no live tree 

stocking.

Associate species: various, frequently ponderosa pine, Utah juniper, or Rocky 

Mountain juniper

Other species: seldom more than two species on a condition

Complete species list: Blue spruce, boxelder, bur oak, common or two-needle pine, curlleaf mountain-mahogany, Douglas-fir, Engelmann spruce, 

Gambel oak, green ash, limber pine, lodgepole pine, narrowleaf cottonwood, paper birch, plains cottonwood, ponderosa pine, quaking aspen, 

Rocky Mountain juniper, subalpine fir, Utah juniper, whitebark pine

Special rules: Used when all live stocking is less than 10 percent. Implies disturbance, but may be used for sparse stands with no disturbance, especially 

with woodland species.

OAK/HICKORY GROUP (T)

Other hardwoods

Predominant species: bur oak

Associate species: none

Other species: boxelder, green ash, paper birch
130 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Special rules: A “catch-all” type, typically for species with a limited geographical 

range.

OTHER WESTERN SOFTWOODS GROUP (T)

Limber pine

Predominant species: limber pine

Associate species: Douglas-fir, ponderosa pine, quaking aspen

Other species: Engelmann spruce, Gambel oak, whitebark pine

PINYON/JUNIPER GROUP (W)

Juniper woodland

Predominant species: Utah juniper, Rocky Mountain juniper

Associate species: limber pine, ponderosa pine, common or two-needle pinyon

Other species: Gambel oak

Pinyon/juniper woodland

Predominant species: common or two-needle pinyon, Utah juniper

Associate species: Rocky Mountain juniper, ponderosa pine, Gambel oak

Other species: Douglas-fir, plains cottonwood

Special rules: Any combination of pinyons and junipers other than Rocky 

Mountain juniper predominate. Pinyons must be present.

Rocky Mountain juniper

Predominant species: Rocky Mountain juniper

Associate species: common or two-needle pinyon, Gambel oak, ponderosa pine

Other species: Douglas-fir, Utah juniper, limber pine

PONDEROSA PINE GROUP (T)

Ponderosa pine

Predominant species: ponderosa pine

Associate species: Gambel oak, Douglas-fir, common or two-needle pinyon, 

Rocky Mountain juniper, Utah juniper

Other species: Engelmann spruce, lodgepole pine, limber pine

WOODLAND HARDWOODS GROUP (W)

Deciduous oak woodland

Predominant species: Gambel oak

Associate species: ponderosa pine, Rocky Mountain juniper, Douglas-fir, common or two-needle pinyon

Other species: Utah juniper, quaking aspen, narrowleaf cottonwood, limber pine

Cercocarpus woodland

Predominant species: curlleaf mountain-mahogany

Associate species: Gambel oak

Other species: Rocky Mountain juniper, common or two-needle juniper, Utah 

juniper
USDA Forest Service Resour. Bull. RMRS-RB-28. 2018 131

Appendix D: Tree Species Groups and Tree Species Measured in 

the Wyoming Annual Inventory With Common Name, Scientific 

Name, and Timber (T) or Woodland (W) Designation

HARDWOODS

Cottonwood and aspen group (T)

Narrowleaf cottonwood (Populus angustifolia)

Plains cottonwood (Populus deltoids)

Quaking aspen (Populus tremuloides)

Other western hardwoods group (T)

Boxelder (Acer negundo)

Bur oak (Quercus macrocarpa)

Green ash (Fraxinus pennsylvanica)

Paper birch (Betual papyrifera)

Woodland hardwoods group (W)

Curlleaf mountain-mahogany (Cercocarpus ledifolius)

Gambel oak (Quercus gambelii)

SOFTWOODS

Douglas-fir group (T)

Douglas-fir (Pseudotsuga menziesii)

Engelmann and other spruces group (T)

Blue spruce (Picea pungens)

Engelmann spruce (Picea engelmannii)

Lodgepole pine (T)

Lodgepole pine (Pinus contorta)

Other western softwoods group (T)

Limber pine (Pinus flexilis)

Whitebark pine (Pinus albicaulis)

Ponderosa and Jeffrey pines group (T)

Ponderosa pine (Pinus ponderosa)

True fir group (T)

Subalpine fir (Abies lasiocarpa)

Woodland softwoods group (W)

Common or two-needle pinyon (Pinus edulis)

Rocky Mountain juniper (Juniperus scopulorum)

Utah juniper (Juniperus osteosperma)
132 USDA Forest Service Resour. Bull. RMRS-RB-28. 2018

Appendix E: Volume, Biomass, and Site Index Equation Sources—

Wyoming

Volume

Chojnacky (1985) was used for common or two-needle pinyon pine, curlleaf 

mountain-mahogany, Rocky Mountain juniper, and Utah juniper volume estimation.

Chojnacky (1992) was used for Gambel oak volume estimation.

Edminster et al. (1980) was used for western Wyoming ponderosa pine volume 

estimation.

Edminster et al. (1982) was used for aspen volume estimation.

Kemp (1956) was used for plains and narrowleaf cottonwood volume estimation.

Myers (1964) was used for lodgepole pine, limber pine, and eastern Wyoming 

ponderosa pine volume estimation.

Myers and Edminster (1972) was used for blue spruce, Douglas-fir, Engelmann 

spruce, and subalpine fir volume estimation.

Biomass

Chojnacky (1984) was used for curlleaf mountain-mahogany biomass estimation.

Chojnacky (1992) was used for Gambel oak biomass estimation.

Chojnacky and Moisen (1993) was used for common or two-needle pinyon pine, 

Rocky Mountain juniper, and Utah juniper biomass estimation.

Van Hooser and Chojnacky (1983) was used for all timber (T) species biomass 

estimation.

Site Index

Brickell (1970) was used for blue spruce, Douglas-fir, Engelmann spruce, limber 

pine, lodgepole pine, ponderosa pine, and subalpine fir site index estimation.

Edminster et al. (1985) was used for aspen, and plains and narrowleaf cottonwood 

site index estimation.

Stage (1966) was used for white fir site index estimation. [Original equations were 

reformulated by J. Shaw; documentation on file at U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Inventory Monitoring, 

Ogden, UT.]

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