Idaho’s Forest Resources, 

2004–2009

Chris Witt, John D. Shaw, Michael T, Thompson, 

Sara A. Goeking, Jim Menlove, Michael C. Amacher, 

Todd A. Morgan, Charles Werstak

United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Resource Bulletin

RMRS-RB-14

July 2012
Witt, Chris; Shaw, John D.; Thompson, Michael T.; Goeking, Sara A.; Menlove, Jim; Amacher, Michael C.; Morgan, Todd 

A.; Werstak, Charles. 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.

Abstract

This report presents a summary of the most recent inventory information for Idaho’s forest lands. The report includes descriptive highlights and tables of area, number of trees, biomass, volume, growth, mortality, and removals. Most of the tables 

are organized by forest type, species, diameter class, or owner group. The report also describes inventory design, inventory 

terminology, and data reliability. Results show that Idaho’s forest land totals 21.4 million acres. Nearly 76 percent (16.2 million acres) of this forest land is administered by the USDA Forest Service. Douglas-fir forests cover almost 6.3 million acres 

or roughly 29 percent of Idaho’s forested lands, making it the most abundant forest type in the State. The lodgepole pine 

type is the second-most common type comprising 11.5 percent of Idaho’s forest land. In terms of number of individual trees, 

subalpine fir is the single most abundant tree species in Idaho. Net annual growth of all live trees 5.0 inches diameter and 

greater on Idaho forest land totaled 376.2 million cubic feet. Average annual mortality totaled nearly 814.6 million cubic feet.

The Authors

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

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

ecology from Idaho State University (contact: chriswitt@fs.fed.us, 208-373-4370).

John D. Shaw is a Forester and Analysis Team Leader with the Interior West Inventory and Analysis Program 

at the USFS 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.

Michael T. Thompson is a Forester and a member of the Analysis Team with the Interior West Inventory and 

Analysis Program at the USFS Rocky Mountain Research Station in Ogden, Utah. He holds a B.S. degree in 

forestry from North Carolina 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.

Jim Menlove is an Ecologist and a member of the Analysis 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.

Michael C. Amacher is a Research Soil Scientist in the Forest and Woodland Ecosystems Research Program 

at the USFS Rocky Mountain Research Station in Logan, Utah. He also serves as the western soils Indicator 

Advisor in the Indicators of Forest Health program. He has B.S. and M.S. degrees in chemistry and a Ph.D. in 

soil chemistry, all from Pennsylvania State University.

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 received a B.A. degree in philosophy and a B.S. 

degree in forest science from Pennsylvania State University and an M.S. degree in forestry from The University 

of Montana.

Charles Werstak is a Biological Scientist and a member of the Analysis Team with the Interior West Inventory 

and Analysis Program at the USFS Rocky Mountain Research Station in Ogden, Utah. He holds a B.S. degree 

in geography from Western Illinois University and an M.S. degree in geography from Utah State University.

Acknowledgments

The Rocky Mountain Research Station gratefully acknowledges the cooperation and assistance of the Rocky Mountain 

Region, Forest Service, U.S. Department of Agriculture; the Bureau of Land Management and Indian Affairs; and the 

National Park Service, U.S. Department of Interior. The authors extend a special note of thanks to the private landowners 

who provided information and access to field sample plots.
Report Highlights

Forest Area

•	 Idaho’s forest land area totals 21.4 million acres.

•	 Unreserved forest land accounts for most (83 percent) of the forest land in

Idaho and totals 17.8 million acres.

•	 Ninety-three percent of Idaho’s unreserved forest land is classified as timberland and 7 percent is classified as unproductive forest land.

•	 Nearly 76 percent of Idaho’s total forest land area, about 16.2 million acres,

is administered by the USDA Forest Service.

•	 Douglas-fir forests cover almost 6.3 million acres and account for 29 percent of forest land in Idaho.

•	 Lodgepole pine forests cover about 2.5 million acres and are the second

most abundant forest type.

•	 After the Douglas-fir forest type group, the fir / spruce / mountain hemlock

group is the second most abundant with 6.0 million acres in Idaho.

Numbers of Trees, Volume, and Biomass

•	 There are an estimated 7.8 billion live trees in Idaho.

•	 Softwood species total 7.1 billion trees or 92 percent of all live trees.

•	 Numbers of subalpine fir trees total nearly 1.5 billion, making this species

the single most abundant tree in Idaho.

•	 The net volume of live trees in Idaho on forest land totals 46.6 billion cubic

feet.

•	 Growing-stock volume on timberland in Idaho totals 39.7 billion cubic feet,

or 84 percent of the total live volume on forest land.

•	 The Douglas-fir species group accounted for the greatest growing-stock

volume with over 11.5 billion cubic feet present in Idaho timberlands.

•	 The total weight of oven-dry biomass on Idaho forest land is 835 million

tons.

•	 Net volume of sawtimber trees on timberland totals 200 billion board feet.

Forest Growth and Mortality

•	 Net annual growth of all live trees 5.0 inches diameter and greater on Idaho

forest land totaled 219.6 million cubic feet.

•	 Average annual mortality totaled nearly 376.2 million cubic feet

•	 Mortality exceeded net growth for four major tree species groups.

•	 Timber harvest for 2010 was 830 MMBF (Scribner), up about 10 percent

from 2009 and approximately equal to 2008; the annual harvest each year

for 2008-2010 were the three lowest harvest totals in Idaho since the second

World War.
Issues in Idaho’s Forests

•	 The annual level of mortality of whitebark pine trees is greatly outpacing

the combined annual basal area growth of survivor trees and ingrowth trees.

•	 Damage agents related to merchantability accounted for the majority of primary damage agents in Idaho’s forests, with diseases being the second most

frequently recorded damage.

•	 A pronounced upward trend in mortality has occurred in lodgepole pine due

to mountain pine beetle infestation outbreaks during the 6 years of annual

inventories in Idaho.

•	 Current inventory data show that there are nearly 708,000 acres of the aspen

forest type in Idaho, as compared to nearly 532,000 acres found during the

previous inventory.

•	 Sixteen different invasive species were documented on 9 percent of the forested plots in Idaho. Canada thistle, spotted knapweed, and meadow hawkweed were the most common species detected.

ii
Contents

Report Highlights .........................................................................................................................iii

Issues in Idaho’s Forests.............................................................................................................iv

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

Idaho’s Forest Inventory .............................................................................................................................. 1

Comparison With Previous Inventories........................................................................................................ 1

Inventory Methods.........................................................................................................................2

Plot Configuration ........................................................................................................................................ 2

Sample Design ............................................................................................................................................ 3

Three-Phase Inventory ................................................................................................................................ 3

Sources of Error........................................................................................................................................... 4

Overview of Tables........................................................................................................................6

Overview of Idaho’s Forest Resources .......................................................................................6

Ecoregion Provinces of Idaho...................................................................................................................... 6

Forest Land Classification ........................................................................................................................... 7

Forest Land Ownership ............................................................................................................................... 9

Forest Type.................................................................................................................................................. 9

Stand Age .................................................................................................................................................. 14

Stand Density Index (SDI)......................................................................................................................... 15

Number of Trees........................................................................................................................................ 18

Live Tree Volume, Biomass, and Sawtimber............................................................................................. 19

Forest Growth and Mortality ...................................................................................................................... 21

Quality Assurance Analysis........................................................................................................................ 24

Other Resources in Idaho’s Forests..........................................................................................27

Down Woody Material................................................................................................................................ 27

Soil Resources in Idaho’s Forests ............................................................................................................. 34

Snags as Wildlife Habitat........................................................................................................................... 38

Idaho Timber Harvest and Forest Products............................................................................................... 40

Issues in Idaho’s Forests............................................................................................................42

Decline of Whitebark Pine ......................................................................................................................... 42

Aspen Mortality.......................................................................................................................................... 45

Mountain Pine Beetle................................................................................................................................. 48

Phase 2 Damage....................................................................................................................................... 49

Old Forests ................................................................................................................................................ 52

Fire in Idaho Forests.................................................................................................................................. 55

Noxious Weeds.......................................................................................................................................... 58

Special Topic—Bridging the Gap Between Periodic and Annual Forest Inventories: 

Caveats and Limitations.........................................................................................................60

Conclusions.................................................................................................................................65

Standard Forest Inventory and Analysis Terminology ............................................................65

References ...................................................................................................................................72

Appendix A: Species Group, Common Name, Scientific Name, and Timber (T) or 

Woodland (W) Designation for Trees Measured in Idaho’s Annual Inventory...................76

Appendix B: Forest Type Groups, Forest Type Names, and Timber (T) or Woodland (W) 

Designationt for Forest Type. ................................................................................................77

Appendix C: Volume, Biomass, and Site Index Equation Sources.........................................78

Appendix D: Standard Reporting Tables...................................................................................79

Appendix E: Soil Indicator Core Tables. .................................................................................126

iii

USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 1

Introduction

Idaho’s Forest Inventory

This report contains highlights of the status of Idaho’s forest resources, with

discussions of pertinent issues based on the first 6 years of inventory under the new

Forest Inventory and Analysis (FIA) annual system (Gillespie 1999). Resource

issues covered in this report were derived from scoping meetings with Idaho data

users conducted in 2009-2010. In 1998, the Agricultural Research Extension and

Education Reform Act (also known as the Farm Bill) mandated that inventories

would be conducted throughout United States’ forests on an annual basis. This

annual system integrates FIA and Forest Health Monitoring (FHM) sampling designs resulting in the mapped-plot design, which includes a nationally consistent

plot configuration with four fixed-radius subplots; a systematic national sampling

design consisting of one plot in each approximately 6,000-acre hexagon; annual

measurement of a proportion of permanent plots; data or data summaries within

6 months after yearly sampling is completed; and a State summary report after 5

years.

Interior West Forest Inventory and Analysis (IWFIA) implemented the new annual inventory strategy starting in Idaho in 2004. The strategy for the Western

United States involves measurement of 10 systematic samples (or subpanels) each

of which represents approximately 10 percent of all plots in the State. The six

inventory years covered in this report are 2004 through 2009, with a few sections

using additional periodic inventory data from earlier years and the “Idaho Timber

Harvest and Forest Products” section using ancillary data from 2010. Although the

Farm Bill requires reports after 5 years, the Idaho report was delayed to give the

IWFIA program time to work through national inconsistencies with past and current forest land definitions.

Comparison With Previous Inventories

Past inventories of Idaho were referred to as periodic inventories where estimates were derived from measurements of all plots in the State over a period of

two to three years. Numerous previous inventories of Idaho’s forest resources have

been completed, most recently in 1981 (Benson and others 1987) and 1991 (Brown

and Chojnacky 1996). Data from new inventories are often compared with data

from earlier inventories to determine trends in forest resources. However, for the

comparisons to be valid, the procedures used in the inventories must be compatible. Idaho’s procedures for past inventories are different enough from present procedures that comparisons between them are not recommended. For example, past

Idaho inventories often did not sample National Forest Systems lands or woodlands. Some data on these lands were provided by the Forest Service National

Forest System staffs, but these data were not collected using IWFIA protocols so

any temporal comparisons are difficult to make. In addition, many definitions of

forest resource attributes have changed since 1981. The impact of these changes

varies by inventory estimate. Forest land definitions, plot configuration, and procedures used to estimate forest type and stand size are some of the significant changes that have occurred since the previous inventory. Some of the factors affecting

definitional differences, such as stocking or crown cover, have been reconciled
2 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

with the past through a process called “plot-filtering,” which re-classified forest

land with 5 to 9 percent cover as a potentially new land class called “other wooded

land.” A more complete description of this process can be found in “Utah’s Forest

Reources, 2000-2005” (DeBlander and others 2010) and a detailed discussion on

comparing periodic to annual data can be found as a “Special Topic” in the “Issues

in Idaho’s Forests” section of this report.

Annual inventory summaries are updated each spring to include the most recent

subpanels of data available to the public. Data may be downloaded in table form

or queried using a variety of online tools (http://fia.fs.fed.us/tools-data/default.

asp). After 2013, a full assessment of ten subpanels of data will be included in the

upcoming 10-year (full cycle) report. In 2014, the re-measurement phase of the

inventory will begin by re-measuring the first subpanel of plot data collected in

2004.

Inventory Methods

Plot Configuration

The national FIA plot design consists of four 24-foot radius subplots configured as a central subplot and three peripheral subplots. 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 5 inches or larger at breast height (d.b.h.) for timber trees, or at root

collar (d.r.c.) for woodland trees, is measured on these subplots. Each subplot contains a 6.8-foot radius microplot with its center located 12 feet east of the subplot

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

In addition to the trees measured on FIA plots, data are also gathered about

the stand or area in which the trees are located. Area classifications are useful for

partitioning the forest into meaningful categories for analysis. Some of these area

attributes are measured (e.g., percent slope), some are assigned by definition (e.g.,

ownership group), and some are computed from tree data (e.g., percent stocking).

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

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

with the area classifications. To accomplish this, plots are mapped by condition

class. A condition class (or condition) is the combination of discrete attributes that

describe the area associated with a plot. These attributes include land use, forest

type, stand origin, stand size, owner group, reserve status, and stand density as

well as other ancillary and computed attributes (Bechtold and Patterson 2005). In

some cases, the plot footprint spans two or more conditions. Field crews assign a

number to the first condition class encountered on a plot. This condition is then

defined by a series of discrete variables attached to it (i.e., land use, stand size,

regeneration status, tree density, stand origin, ownership group, and disturbance

history). Additional conditions are identified if there is a distinct change in any of

the condition-class variables on the plot.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 3

Sample Design

Based on historic national 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 nonoverlapping, 5,937-acre hexagons and established a plot in each hexagon using

procedures designed to preserve existing plot locations from previous inventories.

This base sample, designated as the Federal base sample, was systematically divided into a number of non-overlapping panels, each of which provides systematic

coverage of the State. Each year the plots in a single subpanel are measured, and

subpanels are selected on either a 5-year (eastern regions) or 10-year (western

regions) rotating basis (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. Phase 1 uses remotely sensed data to

obtain initial plot land cover observations and to stratify land area in the population

of interest, such as counties, to increase the precision of estimates. In phase 2, field

crews visit the physical locations of permanent field plots to measure traditional

inventory variables such as tree species, diameter, and height. In phase 3, field

crews visit a subset of phase 2 plots to obtain measurements for an additional suite

of variables associated with forest and ecosystem health. The three phases of the

enhanced FIA program are discussed in the following sections.

Phase 1—Remotely sensed data in the form of aerial photographs, digital orthoquads, and satellite imagery are used for initial plot establishment. Each plot

is assigned a digitized geographic location, and a human interpreter determines

whether a plot has the potential to sample forest or other wooded land based on

remotely sensed data. Plot locations that are accessible to field crews and have the

potential to sample forest or other wooded land are selected for further measurement via field crew visits in phase 2.

The only remote sensing medium used for stratification in Idaho was 2004

MODIS satellite imagery. The spatial resolution of the MODIS imagery used

was 250 meters. Three strata were recognized: forest/other wooded land, nonforest land, and census water. Depending on geography and sampling intensity, geographic divisions are identified within a State for area computation and are referred

to as estimation units. In Idaho, individual counties served as the estimation units.

The area of each estimation unit is divided into strata of known size using the satellite imagery and computer-aided classification. The classified imagery divides the

total area of the estimation unit into pixels of equal size and assigns each pixel to

one of H strata. Each stratum, h, then contains nh ground plots where the phase 2

attributes of interest are observed.

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

defined as:

A

y

A

n

n

n

i

h

H

n

1

1

R = R =

= g

hg

Tg

g hg

ihg

hg

l

l t

where:
4 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

At

g = total forest area (acres) for estimation unit g

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

H = number of strata (3)

nl

hg = number of phase 1 points in stratum h in estimation unit g

nl

g = total number of phase 1 points in estimation unit g

yihg = forest land condition proportion on phase 2 plot i in stratum h in estimation

unit g

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

Phase 2—Field crews record a variety of data for plot locations determined in

phase 1 to sample accessible forest land. Before visiting privately owned plot locations, field crews consult county land records to determine the ownership of plots

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

The field crews determine the location of the geographic center of the center subplot using geographic positioning system (GPS) receivers. They record conditionlevel variables that include land use, forest type, stand origin, stand-size class,

site productivity class, forest disturbance history, slope, aspect, and physiographic

class. For each tree, field crews record a variety of variables including species,

live/dead status, diameter, height, crown ratio, crown class, damage, and decay

status. Office staff apply statistical models using field crew measurements to calculate values for additional variables such as individual tree volume and per unit area

estimates of number of trees, volume, biomass, growth, and mortality.

The standard suite of phase 2 attributes is collected by all FIA regions in a consistent manner. In addition to these national “core” variables, IWFIA collects data

on forest attributes that regional stakeholders find informative and useful. These

include understory vegetation cover and species dominance, noxious weeds, and

down woody material. These data are collected through documented protocols on

all accessible phase 2 forested plots in the Interior West (USFS 2011). These regional attributes are used in the “Noxious Weeds” and “Down Woody Material”

analyses of this report.

Phase 3—The third phase of the enhanced FIAprogram focuses on forest health.

Phase 3 is administered cooperatively by the FIA program, other Forest Service

programs, other Federal agencies, State natural resource agencies, universities,

and the Forest Health Monitoring (FHM) program. Phase 3 is the ground survey

portion of the Forest Health Monitoring (FHM) program and was integrated into

the FIA program in 1999. 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 95,000 acres.

Phase 3 measurements are obtained by field crews during the growing season and

include an extended suite of ecological data. Because each phase 3 plot is also a

phase 2 plot, the entire suite of phase 2 measurements is collected on each phase

3 plot at the same time as the phase 3 measurements. Soil structure and chemistry,

and crown condition are two attributes collected at the phase 3 subsample. Phase 3

soil data is used in the “Soil Resources” section of this report.

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 error

they would not have if every member of the population had been observed and included in the estimate. The 2004-2009 FIA inventory of Idaho is based on a sample
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 5

of 5,295 plots systematically located across the State (a total area of 53.5 million

acres); a sampling rate of approximately one plot for every 10,101 acres.

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 every estimate is an associated sampling error that is typically

expressed as a percentage of the estimated value but that 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). This 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. The sampling errors for Statelevel estimates are presented in Appendix D (table 37).

Users may compute statistical confidence for subdivisions of the reported data

using the formula below. 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. The formula is:

SEs = SEt X

X

s

t

SEs = sampling error for subdivision of State total.

SEt = sampling error for State total.

Xs = sum of values for the variable of interest (area, volume, biomass, etc.) for

subdivision of State total.

Xt = sum of values (area, volume, biomass, etc.) for State total.

Measurement Error—Errors associated with the methods and instruments used

to observe and record the sample attributes are called measurement errors. On FIA

plots, attributes such as the diameter and height of a tree are measured with different 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 tree diameter consistently taken at an incorrect place on the tree—then the estimates that use this observation (e.g., calculated 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 process. To ensure that all

FIA observations are made to the highest standards possible, a Quality Assurance

Program is an integral part of all FIA data collection efforts (see the “Quality

Assurance Analysis” section of this report for more details).

Prediction error—Errors associated with using mathematical models (such as

volume models) to provide information about attributes of interest based on sample attributes are referred to as prediction errors. Area, number of trees, volume,

biomass, growth, removals, and mortality are the primary attributes of interest

presented in this report. Area and number of trees estimates are based on direct observation and do not involve the use of prediction models; however, FIA estimates

of volume, biomass, growth, and mortality used model-based predictions in the

estimation process.
6 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Overview of Tables

Forest Inventory and Analysis is currently working on a revised national core

table set that will expand the suite of tabular information to incorporate more of the

core FIA Program, using both phase 2 and 3 data. Appendix D contains an interim

set of tables supporting this report, using Idaho annual data for the years 2004

through 2009. There are a total of 37 tables with statistics for land area, number

of trees, wood volume, biomass (weight), growth, mortality, and sampling errors.

Table 1 is the only table that includes all land types or land status; the rest include

only accessible forest land or timberland. Table 37 shows sampling errors for area,

volume, net growth, and mortality at the 67 percent confidence level. Appendix

E includes tables derived from soil data collected from the phase 3 subsample.

Additional tables that supplement specific sections are included in the body of this

report and are numbered consecutively, using Roman numerals, as they appear in

the document.

Overview of Idaho’s Forest Resources

Ecoregion Provinces of Idaho

Issues and events that influence forest conditions often occur across forest types,

ownerships, and political boundaries. As a result, scientists, researchers, and land

managers must also find a way to assess and treat these issues in a boundaryless

way. Ecoregions are often used as a non-political land division to help researchers

study forest conditions. An ecoregion is a large landscape area that has relatively

consistent patterns of topography, geology, soils, vegetation, climate, and natural processes (Shinneman and others 2000). Many smaller ecosystems may reside

within an ecoregion.

Idaho is at the confluence of five ecoprovinces: (1) the Intermountain SemiDesert Province dominates the southern part of the State, (2) the Great PlainsPalouse Dry Steppe Province encompasses a small portion of the northwestern part

of the State, (3) the Northern Rocky Mountain Forest—Steppe-Coniferous Forest

Alpine Meadow Province encompasses the northern part, (4) the Middle Rocky

Mountain Forest—Steppe-Coniferous Forest Alpine Meadow Province in the central portion of the State, and (5) the Southern Rocky Mountain Forest—SteppeConiferous Forest Alpine Meadow Province in the southeast (Bailey 1995).

The Northern, Middle, and Southern Rocky Mountain Steppe ecoprovinces

contain the majority of Idaho’s forest resources. These provinces also contain the

most forested area and greatest variety of forest types. Bailey (1995) describes

these areas as follows:

Northern Rocky Mountain Forest—Steppe-Coniferous Forest Alpine Meadow

Province:

Well-marked life belts are a striking feature of the Northern Rocky Mountain 

Steppe Province. In the uppermost (alpine) belt, trees are absent. The subalpine 

belt is dominated in most places by Engelmann spruce and subalpine fir. Western 

redcedar and western hemlock are characteristic of the montane belt. Associated 
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 7

trees include Douglas-fir (found throughout the region), along with western white 

pine, western larch, grand fir, and western ponderosa pine (found in the south). 

In these forests, areas that have been burned or cut are invaded first by larch, a 

deciduous conifer. White pine may crowd out the larch, then be replaced by hemlock, redcedar, and lowland white fir. Depending on latitude, the lower part of the 

montane belt may be interspersed with grass and sagebrush.

Middle Rocky Mountain Forest—Steppe-Coniferous Forest Alpine Meadow

Province:

Altitudinal zones are also evident in the Middle Rocky Mountain Steppe Province. 

Below the subalpine zone, Douglas-fir is the climax dominant, with grand fir as an 

associate west of the continental divide, chiefly on west-facing slopes. Lodgepole 

pines and grasses grow principally in the basins and ranges in the eastern and 

southeastern part of the province. Below the Douglas-fir belt, ponderosa pine is 

dominant to the west of the continental divide, constituting a xerophytic forest. The 

lower slopes of the mountains and the basal plain are dominated by sagebrush 

semidesert or steppe.

Southern Rocky Mountain Forest—Steppe-Coniferous Forest Alpine Meadow

Province:

The Southern Rocky Mountain Steppe province is noted for its pronounced vegetational zonation, controlled by a combination of altitude, latitude, direction of 

prevailing winds, and slope exposure. Generally, the various zones are at higher 

altitudes in the southern part of the province than in the northern, and they extend 

downward on east-facing and north-facing slopes and in narrow ravines and valleys subject to cold air drainage. The uppermost (alpine) zone is characterized 

by alpine tundra and the absence of trees. Directly below it is the subalpine zone, 

dominated in most places by Engelmann spruce and subalpine fir. Below this area 

lies the montane zone, characterized by ponderosa pine and Douglas-fir, which frequently alternate--ponderosa pine dominates on lower, drier, more exposed slopes, 

and Douglas-fir is predominant in higher, moister, more sheltered areas. After fire 

in the subalpine zone and in the upper part of the montane zone, the original forest 

trees are usually replaced by aspen or lodgepole pine.

The remaining two provinces are characterized by dry rocky foothills, mesas,

and plateaus, north and south running basins and ranges, and lava fields. The predominant community types in the areas are sagebrush steppe and shortgrass prairie. Forest types in these regions include western juniper, with some Douglas-fir,

aspen, and other hardwood species found along riparian zones and where soils and

moisture permit.

Forest Land Classification

Historically, FIA has used 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.

The first division of forest land is unreserved forest land and reserved forest land.

Unreserved forest land is considered available for harvesting activity where wood

volume can be removed for timber products. Reserved forest land is considered

unavailable for any type of wood utilization management practice through administrative legislation.
8 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Unreserved forest land is further divided into timberland and unproductive forests. In the past, forest types have often been separated into timber and woodland

types. Timber types are characterized by stands where the plurality of stocking is

from species where diameter is measured at breast height, as opposed to root collar

(woodland types). Timberland is further defined as forest land capable of producing 20 cubic feet of wood per acre per year of trees designated as a timber species

and not withdrawn from timber production. Unproductive forests are, because of

species characteristics and site conditions, not capable of producing 20 cubic feet

of wood per acre per year of trees designated as a timber species and not withdrawn from timber production (see the “Standard Forest Inventory and Analysis

Terminology” section of this document).

Reserved forest land is further divided into productive and unproductive forests.

Productive forest land is capable of producing 20 cubic feet of wood per acre per

year of trees designated as a timber species but is withdrawn from timber production. Unproductive reserved land is, because of a combination of species characteristics and site conditions, not capable of producing 20 cubic feet of wood per

acre per year of trees designated as a timber species and withdrawn from timber

production.

The State of Idaho encompasses 53.5

million acres of land area, of which 21.4

million acres were estimated by FIA as

forest land (fig. 1). Unreserved forest land

accounts for most (83 percent) of the forest land in Idaho and totals 17.8 million

acres (table 2). Ninety-three percent of

Idaho’s unreserved forest land is classified as timberland and 7 percent is classified as unproductive forest land. Reserved

forests account for 17 percent, or 3.6 million acres of total forest land.

Figure 1: Land class map depicting 

lands with 10 percent or more forest 

cover in Idaho.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 9

Forest Land Ownership

Nearly 76 percent of Idaho’s total forest land area, about 16.2 million acres, is

administered by the USDA Forest Service (fig. 2). The National Forest Service

System’s land in Idaho consists of 11 different National Forests. Almost 79 percent of National Forest System’s forest land is classified as unreserved forest land.

About 12.2 million acres, or 96 percent, of National Forest System’s forest land

is classified as unreserved timberland (table 2). The State government manages

1.3 million acres of forest land in Idaho. Most of this forest land—about 98 percent—is classified as unreserved. Over 91 percent of Idaho’s State controlled forest land meets the conditions to qualify as unreserved timberland. Privately owned

forest land totals 2.8 million acres. Private landowners are a diverse group in Idaho

consisting of private individuals and corporations. All private forest land is in the

unreserved owner class and 91 percent is classified as timberland. The remaining

amount of forest land in Idaho is controlled by the National Park Service (NPS),

the Bureau of Land Management (BLM), and the Department of Defense. Over

944 thousand acres are controlled by the BLM, another 80 thousand acres are

controlled by the NPS, and 32 thousand acres are controlled by the Department of

Defense.

Forest Type

Forest type is a classification of forest land based on the species forming a plurality of living trees growing in a particular forest. The distribution of forest types

across the landscape is determined by factors such as climate, soil, elevation, aspect, and disturbance history. Forest type names may be based on a single species

or groups of species. Forest types are an important measure of diversity, structure,

and successional stage. Loss or gain of a particular forest type over time can be

used to assess the impact of major disturbances such as fire, weather, insects, disease, and man-caused disturbances such as timber harvesting activity.

Figure 2: Area of forest 

land by owner group, 

Idaho, 2004-2009.
10 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

The most abundant forest type group in Idaho is the Douglas-fir group (fig. 3).

Douglas-fir forests cover nearly 6.3 million acres and account for 29 percent of forest land in the State (fig. 4a, table 3). Second in abundance, the fir/ spruce/ mountain hemlock forest type group totals just over 6 million acres (fig. 4b). Subalpine

fir accounts for the largest portion (2.3 million acres) of the forest area classified in

the fir/spruce/mountain hemlock type group. Lodgepole pine forest types cover 2.5

million acres and are the third most abundant forest type group (fig. 4c). Next in

order of abundance are non-stocked forests (1.7 million acres), the ponderosa pine

group (1.6 million acres), the hemlock/ sitka spruce group (887 thousand acres),

and the aspen/ birch group (795 thousand acres).

Figure 3: Area of forest land by forest type group, Idaho, 2004-2009. See appendix A and B for species and forest 

types included in each group.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 11

Figure 4a: Land class map depicting crown forest cover in Idaho with the general locations of 

plots containing the Douglas-fir forest type group, Idaho, 2004-2009.
12 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Figure 4b: Land class map depicting percent crown cover in Idaho with the general locations 

of plots containing fir/spruce/mountain hemlock forest type group, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 13

Figure 4c: Land class map depicting percent crown cover in Idaho with the general locations of plots 

containing lodgepole pine forest type group, Idaho, 2004-2009.
14 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Stand Age

The present age structure of Idaho’s forest area, in terms of stand age and forest

type group composition, provides insight into prospective shifts in stand composition over time. On every FIA plot that samples forest land, a stand age is calculated. If there are trees available for suitable increment core extraction, a stand

age is estimated based upon the average age of only those trees that fall within

the calculated stand-size assignment. For example, suppose an FIA plot sampled

a softwood forest type where about 30 percent of the live trees were in the large

diameter stand-size (trees at least 9.0 inches d.b.h. and larger) and 70 percent were

in the medium diameter stand-size class (trees between 5.0 and 9.0 inches d.b.h.).

Since the stand would be classified as a medium diameter stand size class, only the

medium size trees would be used in determining stand age. There are limitations

to collecting data for stand age computation. Certain tree species, especially those

that are very old, prohibit repeatable measures of increment cores. Certain stand

types, such as Gambel oak, that are dominated by small-diameter trees are very

difficult to accurately assign a stand age. All nonstocked forest conditions—i.e.,

those forested areas that have less than 10 percent stocking of live trees because of

disturbance—are assigned a stand age of zero.

The largest proportion of Idaho’s forested land is between 60 and 120 years

of age (table 6). Over 46 percent, or almost 10 million acres, of the forest land is

between 60 and 120 years of age. About 20 percent of the forest land is in stands

under 21 years of age and 3 percent are over 200 years of age.

There is a considerable difference in stand age distribution between the major

forest type groups in the State (figs. 5a and 5b). The other western hardwoods

group is the oldest with half of the forest area in stands over 140 years old. Twenty

percent of pinyon-juniper stands are over 140 years old, making it the next oldest

group. Aspen, which is generally shorter lived than most Idaho conifer species, is

characterized by a larger number of stands in the younger age classes with over 98

Figure 5a: Distribution of forest land by stand age class and more common forest type groups in Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 15

percent of aspen forests in stands less than 100 years old. This makes the aspen/

birch forest type group the youngest of those occupying greater than 100 thousand

acres in Idaho. All three of the most abundant groups—the Douglas-fir, the spruce/

fir/ mountain hemlock, and the lodgepole pine groups—have their highest proportion of area in the 81 to 100 year age class at 22 percent, 17 percent, and 23 percent

respectively.

Stand Density Index (SDI)

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 live 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., Smith and Long 1987; Lilieholm and others 1994; Long and Shaw

2005).

SDI is usually presented as a percentage of a maximum SDI for each forest

type. Maximum SDI is rarely, if ever, observed in nature at the stand scale because the onset of competition-induced (self-thinning) mortality begins to occur at

about 60 percent of the maximum SDI. Average maximum density, which is used

in normal yield tables, and is equivalent to the A-line in Gingrich-type stocking

diagrams (Gingrich 1967) is equal to approximately 80 percent of maximum SDI.

There are several reasons why stands may have low SDI. Stands typically have

low SDI 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 re-occupied 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

Figure 5b: Distribution of forest land by stand age class and less common forest type groups in Idaho, 2004-2009.
16 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

at low density indefinitely, because limitations on physical growing space do not

permit full site occupancy. A site is considered to be fully occupied at 35 percent

of maximum SDI. At 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).

Originally developed for even-aged stands, SDI can also be applied to unevenaged 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. Because FIA data include stands covering the full

range of structure, the maximum SDIs are currently being revised for FIA forest

types (Shaw and Long, in prep.). The provisional revised maximum SDIs, which

are compatible with FIA computation methods, are shown in table I. 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.

The distribution of SDI values in Idaho is relatively balanced. Figure 6 shows

that stands appear to be well-stocked, with over 47 percent of forest acres at least

fully occupied (SDI equal to 35 percent or greater). The other 53 percent is relatively evenly distributed over the lower range of stocking. Over 14 percent of

Idaho’s forests are in the range where competition-induced mortality is expected

(SDI equal to 60 percent or greater).

Stands with SDI between 35 and 60 percent of maximum SDI (full stocking

zone) are desirable from a forest management perspective because that density

range maximizes stand growth and minimizes competition-induced mortality;

other objectives, such as fuel reduction or maintenance of wildlife habitat characteristics, may warrant lower relative densities. The proportion of Idaho’s forests

in the full stocking zone (32.7%) is comparable to the proportions found in other

Table I: Maximum Stand Density Index (SDI) of forest types found in Idaho.

Forest Type Maximum SDI

Western juniper 320

Cottonwood 360

Pinyon-juniper woodland 370

Ponderosa pine 375

Juniper woodland 385

Limber pine 410

Cercocarpus woodland 415

Rocky Mountain juniper 425

Western larch 430

Subalpine fir 470

Grand fir 475

Unknown / nonstocked 475

Douglas-fir 485

Engelmann spruce / subalpine fir 485

Aspen 490

Whitebark pine 500

Engelmann spruce 500

Lodgepole pine 530

Intermountain maple woodland 540

Mountain hemlock 56

Western hemlock 600

Other hardwoods 645
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 17

interior western States (Arizona 25.2%, Colorado 34.9%, Montana 32.5%, Utah

32.0%). At 14.4 percent, the proportion of area in the competition mortality zone

is somewhat lower than is found in other interior western States (Arizona 15.8%;

Colorado 25.3%, Montana 19.6%, Utah 20.0%). The relatively small proportion

of acreage in this density range is likely due to a combination of density-reducing

natural disturbances, such as fire and insect infestation, and management activities, such as thinning treatments. Because excessive density is considered a risk

factor for many damaging agents, Idaho forests may have a lower risk rating for

certain agents. Given that several damaging agents are currently active in Idaho

(see the “Issues in Idaho’s Forests” section of this document), it is expected that the

proportion of high-density acreage will decrease further over time. Management

activities designed to reduce risks, such as fuel reduction treatments, will have

a similar effect. At the same time, many lower-density stands should increase in

relative density. This may lead to an eventual increase in the area of well-stocked

forest land.

Number of Trees

A measure of the number of live trees is needed in a variety of silvicultural,

forest health, and habitat management applications. To be meaningful, numbers of

trees are usually combined with information about the size of the trees. Younger

Figure 6: Distribution of stand density on Idaho forest land, Idaho, 2004-2009.
18 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

forest stands are usually comprised of large numbers of small-diameter trees,

whereas older forest stands contain small numbers of large-diameter trees.

There are an estimated 7.8 billion live trees ≥1 inch d.b.h. or d.r.c. in Idaho (table 10). Softwood species total 7.1 billion trees or 92 percent of the trees in Idaho

(fig. 7). Over 65 percent of softwood trees are under 5.0 inches in diameter and

nearly 5 percent are 15.0-inches and larger in diameter. The true fir species group

is the most abundant softwood species group accounting for 38 percent (2.7 billion

trees) of the softwood total. This group consists of grand fir and subalpine fir. Next

in abundance is the Douglas-fir group at 1.3 billion trees. The Douglas-fir species

accounts for all trees in this group. Third in abundance is the lodgepole pine species group at 1.26 billion trees. Lodgepole pine is the only species represented in

this group. Tables 10 and 11 in Appendix D show the size-class distribution by

species group for these trees.

The cottonwood and aspen species group accounts for the majority (51 percent)

of the hardwood species occurring in Idaho. Quaking aspen is a very important tree

in Idaho. Stands of aspen are esthetically appealing and provide excellent habitat

for a wide variety of wildlife. Numbers of aspen trees total nearly 330 million making this species the single most abundant hardwood tree in Idaho. Most aspen trees

in Idaho are concentrated in the smaller diameter classes. Sixty-five percent of all

live aspen stems are lessthan three inchesin diameter. The western woodland hardwoods species group is the next most abundant group with an estimated 276 million trees. This group includes bigtooth maple and curlleaf mountain-mahogany.

Figure 7: Number of live trees ≥1 inch d.b.h./ d.r.c on forest land by species group and diameter class, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 19

Live Tree Volume, Biomass, and Sawtimber

The amount of cubic-foot volume of wood in a forest is important for determining the sustainability of current and future wood utilization. The forest

products industry is interested in knowing where available timber volume is located, who owns it, the species composition, and the size distribution. Biomass

estimates are based on gross volumes; they exclude foliage and include all live

trees 1.0 inches in diameter and larger.

The net volume of live trees in Idaho on forest land totals 47.2 billion cubic

feet (table 12). Eighty percent, or 37.8 billion cubic feet, is located on lands

managed by the National Forest System. Ten percent, or 4.8 billion cubic feet, is

under private ownership. Three percent, or 1.4 billion cubic feet, is on Federal

lands other than national forests. The remainder, about 3.2 billion cubic feet, is

on lands administered by the State of Idaho. The total weight of oven-dry aboveground biomass on Idaho forest land (using regional equations, see table 29a) is

853 million tons, of which 734 million tons reside on Federal lands, 56 million

tons on State lands, and the remaining 92 million tons on private land.

Various factors affect whether timber is available for harvest. Three significant factors are ownership status, productivity, and merchantability standards.

Timber volume on reserved forest land—land permanently reserved from wood

products utilization through statute or administrative designation—is considered

land that will not be harvested. Timberland is unreserved forest land capable of

producing in excess of 20 cubic feet per acre per year of wood. Forest land not

capable of meeting this productivity threshold is assumed to have a low probability of being harvested. Historically, FIA has segregated live-tree volume based

on growing-stock classification. Growing-stock trees are live trees that possess,

or have the potential, to produce an 8-foot sawlog that meets required merchantability standards (see the “Standard Forest Inventory and Analysis Terminology”

section of this document). Therefore, the amount of growing-stock volume on

timberland can be considered a reasonable benchmark for the amount of timber

that is potentially available for harvest. Growing-stock volume on timberland in

Idaho totals 40 billion cubic feet, or 84 percent of the total live volume on forest land (fig. 8). Net volume of sawtimber trees on timberland totals 200 billion

board feet (table 19).

Douglas-fir and grand fir together account for almost half (49 percent) of all

growing-stock volume on timberland (fig. 9). Next in abundance, lodgepole pine

totals 4.3 billion cubic feet of growing-stock volume. Growing-stock volume of

subalpine fir total 3.4 billion cubic feet and ranks fourth. Douglas-fir and grand

fir also account for the majority of sawtimber volume (103 billion board feet).
20 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Figure 8: Volume of live trees on forest land by ownership status, productivity, and merchantability status, Idaho, 

2004-2009.

Figure 9: Volume of growing-stock trees on timberland by species group, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 21

Forest Growth and Mortality

Two common measures of forest vigor and sustainability are tree growth and mortality. Growth, as reported here, is the average annual growth volume calculated

from a sample of tree increment core measurements based on the previous 10 years

of radial growth. Mortality, as reported here, is the average annual net volume of

trees that have died in the 5 years prior to the year of measurement. The reason behind this growth and mortality estimation procedure in Idaho is that the inventory

data are limited to initial plot measurements. Complete remeasurement data for the

State—where the status of the plot and all trees on the plot are known at two pointsin

time—will not be available until all ten panels of data are completed and remeasurement begins in the eleventh year.

The relationship between growth and mortality quantifies the change in inventory volume over time. Gross growth minus mortality approximates the average annual change in inventory volume not including the average annual volume removed

through timber harvesting. Net annual growth of all live trees 5.0 inches diameter and

greater on Idaho forest land totaled 376.2 million cubic feet while mortality totaled

nearly 814.6 million cubic feet (tables 22 and 25). Figure 10 illustrates the relationship between net growth and mortality by ownership group in Idaho. Mortality of all

trees on forest land controlled by National Forest Systems lands totaled 757.9 million cubic feet and exceeded net growth on this owner group by more than sevenfold.

In contrast, net growth exceeded mortality on privately owned forests: net growth

totaled 168.8 million cubic feet compared to 25.9 million cubic feet of mortality.

Figure 10: Net annual growth and mortality on forest land by ownership group, Idaho, 2004-2009.
22 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Figure 11 illustrates the relationship between net growth and mortality for the

major species and species groups in Idaho. Of the ten species groups listed, mortality exceeded net growth for four species groups. The most striking relationship

between net growth and mortality occurred in lodgepole pine. Lodgepole pine recorded –75.3 million cubic feet of net growth compared to 209 million cubic feet of

mortality. Whitebark pine—an important producer of food for wildlife in Idaho and

other States—also recorded a negative net growth of –16.4 million cubic feet compared to 23.9 million cubic feet of mortality. Mortality of Douglas-fir totaled 240.7

million cubic feet compared to 56.3 million cubic feet of net growth. Mortality of

the true fir group also exceeded net growth. Net growth exceeded mortality for the

ponderosa pine, western larch, western redcedar, western hemlock, Engelmann and

other spruces, and aspen species groups.

Since high mortality is the driving force behind the large reductions in gross

growth, further examination of this change component by other resource attributes

can help explain the factors behind the high level of tree volume estimated to have

died in the previous 5 years. Significant differences were observed in per-acre estimates of mortality between major ownership groups and reserved status. Converting

the State-level estimates of mortality into per-acre estimates removes the effect of

differences in the amount of forest land controlled by different ownership groups.

Across all ownerships, the per-acre estimate of annual mortality volume averages

38.1 cubic feet per year on forest land. Mortality on reserved forest land was substantially higher than unreserved land. Average annual mortality on reserved land

Figure 11: Net annual growth and mortality on forest land by species and species group, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 23

averaged 74.3 cubic feet per acre compared to 30.8 cubic feet per acre on unreserved

forest land. Figure 12 illustrates per-acre estimates of mortality by two major owner

categories and reserved status. National Forest Systems lands classified as reserved

recorded the highest average level of per-acre mortality at 76.2 cubic feet, which is

over seven times higher than the per-acre estimate recorded on unreserved land controlled by private landowners, other Federal agencies, and State agencies.

Figure 13 illustrates per-acre estimates of mortality by reserved status and cause

of death. All trees classified as mortality are assigned a cause of death in the field.

Drawing conclusionsfrom mortality estimates by cause of death should be done with

caution. The actual agent that caused a tree’s death may be difficult, if not impossible, to determine. The cause of death category of “other” includes trees that have

died due to reasons the field crews are unable to determine. Interactions between

insects and diseases are complex and make identification of damaging agents difficult. Mortality due to fire accounted for the majority (37.9 percent) of total mortality.

Insects were the second leading contributor to mortality, accounting for 26 percent

of total mortality. Disease accounted for 20 percent. There was a very significant

difference in the level of fire-caused per-acre mortality recorded on reserved forest

land (fig. 13).

The high mortality resulted in a very significant reduction in gross growth for

several species and species groups. By ownership, mortality is highest on National

Forest System’s forest land especially forest land classified as reserved. Mountain

pine beetle infestations are likely contributing to much of the lodgepole pine mortality. Lodgepole pine accounted for 68 percent of the mortality volume determined

to be caused by insects. Trends in lodgepole pine mortality believed to have been

caused by mountain pine beetle are examined in the “Mountain Pine Beetle” section

in the “Issues in Idaho’s Forests” chapter.

Figure 12: Average annual per-acre mortality on forest land by two major owner categories and reserved status, Idaho, 

2004-2009.
24 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Quality Assurance Analysis

FIA employs a Quality Assurance (QA) Program to ensure the quality of all

collected data. The goal of the QA program is to provide a framework to assure

the production of complete, accurate, and unbiased forest information of known

quality. Specific Measurement Quality Objectives (MQO) for precision are designed to provide a performance objective that FIA strives to achieve for every

field measurement. These data quality objectives were developed from knowledge

of measurement processes in forestry and forest ecology, as well as the program

needs of FIA. The practicality of these MQOs, as well as the measurement uncertainty associated with a given field measurement, can be tested by comparing data

from blind check plots. Blind check data are paired observations where, in addition

to the field measurements of the standard FIA crew, a second QA measurement of

the plot is taken by a crew without knowledge of the first crew’s results (Pollard

and others 2006). The QA data for this analysis were collected between 2001 and

2005 and then compared for measurement precision between two independent FIA

crews’ observations. Therefore, for many FIA variables, the data quality is measured by the repeatability of two independent measurements.

The results of the QA analysis for this reporting period are presented in tables

II and III. Table II describes tolerances for condition-level variables, and table

III describes tree-level variables. Tolerances are the “accepted” range of variability between two independent observations, for checking or comparison purposes.

Figure 13: Average annual per-acre mortality on forest land by reserved status and cause of death, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 25
26 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 27

Each variable and its associated 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 times out of the total records the data fell

outside the tolerance. For example, table III shows that there were 2,119 paired

records for the variable “d.b.h.” (diameter at breast height). At the 1X tolerance

level, almost 89 percent of those records fell within plus or minus one-tenth inch

of each other, for each 20.0 inches of d.b.h. observed. This percentage is referred

to as the observed compliance rate. MQOs for each variable consist of two parts,

a compliance standard and a measurement tolerance, and can be compared to the

observed compliance rate to determine that variable’s performance.

The information in tables II and III shows variables with varying degrees of

repeatability. For example, one condition-level regional variable that appears fairly

repeatable is “percent bare ground.” At the 1X tolerance level, its observed compliance rate was 96 percent for 92 paired observations that were within plus or

minus 10 percent of each other. In contrast, the compliance rate for “habitat type

1,” which has no tolerance variability, was only 45 percent for the same observations. Habitat types are an important variable for forest management. Accurate

determination could provide an insight to successional status when combined with

existing vegetation (such as tree numbers, size class, and species by habitat types

or series) thus warranting further investigations into the potential repeatability issues associated with evaluating habitat type.

The tree-level variable “d.b.h.,” as mentioned above, is more repeatable when

compared to the regional variable “tree age,” which has a 1X tolerance compliance

rate of only 12 percent. This is probably due to the difficulty of obtaining accurate

tree ages. Several factors that might affect inconsistent tree ages are (1) tree too

large to reach the center, (2) rings too close or faded to read accurately, and (3)

variation in age estimation when not hitting tree center (pith). Although not much

can be done about the first two situations, QA data can be used to develop better

field procedures for the last, especially for critical variables such as tree age.

As more blind check information becomes available, it might become apparent

that a variable’s MQO needs to be adjusted accordingly to better reflect the realistic expectation of quality for that variable. As a result, MQO’s should be used not

only to assess the reliability of FIA measurements and whether current standards

are being met, but also to provide data collection experts with the information

necessary to improve the current data collection system. This process can improve

repeatability, or lead to elimination of variables that prove to be unrepeatable.

Other Resources in Idaho’s Forests

Down Woody Material

Down woody material (DWM) is an important component of forests that greatly impacts fire behavior, wildlife habitat, soil stabilization, and carbon sources.

Some examples of DWM are fallen trees, branches, and leaf litter commonly found

within forests in various stages of decay. The main components of DWM include

fine woody debris (FWD), coarse woody debris (CWD), litter, and duff. FWD

comprises the small diameter (1- to 3-inch) fire-related fuel classes (1-hr, 10-hr,

100-hr), and CWD comprises the large diameter (3-inch +) 1000-hr fuels.
28 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Nationally, DWM are measured on phase 3 (P3) plots. In 2006, due to the increasing need for more intensive DWM information, IWFIA initiated a phase 2

(P2) DWM inventory in all its annual States. This DWM analysis used regional

P2 protocols (USFS 2006-2009) for data collected from 2006 to 2009. Due to the

presence of snow or other hazardous conditions, not all DWM components were

able to be sampled on all plots. Only plots that sampled all six DWM components

were included.

The random distribution of four annual subcycles of P2 DWM plots is displayed

in figure 14. This shows the total DWM biomass (tons per acre) by FIA survey

unit for 1,553 plot/conditions in Idaho. In general, DWM biomass is highest in the

northern and central parts of the State; this distribution reflects the distribution of

forest types. The northern forest types western larch, western hemlock, and western redcedar have the highest DWM biomass estimates; while the southern forest

types western juniper, Rocky Mountain juniper, and juniper woodlands have the

lowest.

Table IV shows the mean biomass (tons per acre) by DWM component, number of sampled plot/conditions, and average elevation for FIA survey units. The

Figure 14: Plot distribution of total DWM 

biomass (tons per acre) by FIA survey 

unit, Idaho, cycle 2, subcycles 3-6, 

2006-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 29

northern survey unit has the highest mean DWM, at 22.4 tons/acre, and the southeastern survey unit has the lowest, at 15.49 tons/acre. The mean DWM for the

entire State is 19.2 tons/acre. Specific DWM components mostly show a similar

pattern, with the southeastern and southwestern units sometimes showing values

similar to one another. The exception is the litter component, where the southwestern survey unit has the highest mean tons/acre. Table V shows the mean biomass

(tons per acre) by DWM component, number of plot/conditions sampled, and average elevation for forest type groups and forest types. Western larch has the highest

mean DWM at 33.6 tons/acre, and the lowest is 3.7 tons/acre for juniper woodland.

Some of the forest types in this analysis may not be representative due to small

sample sizes.

Table IV—Average elevation and DWM loadings by FIA survey unit with number of plots, Idaho 2006-2009.

FIA Survey Unit

Number of 

plots Elevation CWD

FWD 

large

FWD 

medium

FWD 

small Duff Litter Total DWM

Northern 741 4,458 7.4 2.4 0.5 0.2 8.7 3.1 22.4

Southwestern 327 6,110 5.4 1.7 0.4 0.1 6.2 3.8 17.7

Southeastern 485 7,164 5.4 1.6 0.3 0.1 5.5 2.5 15.5

Totals 1,553 5,651 6.4 2.0 0.4 0.2 7.2 3.1 19.2

Table V—Average elevation and DWM loadings by forest type group and forest type. Idaho, 2006-2009.

Forest type group and forest 

type

Number of 

plots Elevation CWD

FWD 

large

FWD 

medium

FWD 

small Duff Litter

Total 

DWM

Pinyon-juniper group

Rocky Mountain juniper 4 5,913 1.7 0.9 0.3 0.0 0.9 1.2 5.0

Juniper woodland 15 5,466 0.0 0.1 0.1 0.0 1.5 1.9 3.7

 Total 19 5,560 0.4 0.3 0.2 0.0 1.3 1.7 3.9

Douglas-fir group

Douglas-fir 447 5,548 4.7 1.9 0.5 0.2 5.7 2.4 15.4

 Total 447 5,548 4.7 1.9 0.5 0.2 5.7 2.4 15.4

Ponderosa pine group

Ponderosa pine 117 4,571 4.2 1.6 0.4 0.1 9.2 6.9 22.4

 Total 117 4,571 4.2 1.6 0.4 0.1 9.2 6.9 22.4

Western white pine group

Western white pine 3 4,078 6.0 1.1 0.3 0.1 7.2 3.8 18.6

 Total 3 4,078 6.0 1.1 0.3 0.1 7.2 3.8 18.6

Fir-spruce-mountain hemlock 

group

Engelmann spruce 52 6,505 12.0 1.1 0.3 0.1 8.2 1.9 23.5

Engelmann spruce-subalpine 

fir 44 6,347 10.0 1.6 0.4 0.2 10.6 2.4 25.2

Grand fir 141 4,134 9.0 4.9 0.9 0.3 8.9 3.0 26.8

Subalpine fir 152 6,979 8.6 1.3 0.3 0.1 6.0 1.7 18.0

Mountain hemlock 16 5,584 7.8 1.3 0.5 0.2 3.5 1.1 14.3

 Total 405 5,804 9.3 2.5 0.5 0.2 7.7 2.2 22.4
30 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Table V—Continued.

Forest type group and forest 

type

Number of 

plots Elevation CWD

FWD 

large

FWD 

medium

FWD 

small Duff Litter

Total 

DWM

Lodgepole pine group

Lodgepole pine 177 6,324 7.3 1.5 0.3 0.1 9.6 3.3 22.0

 Total 177 6,324 7.3 1.5 0.3 0.1 9.6 3.3 22.0

Hemlock-Sitka spruce group

Western hemlock 27 3,435 11.4 3.1 0.6 0.3 14.8 3.2 33.4

Western redcedar 48 3,449 14.0 2.2 0.5 0.2 11.8 3.7 32.4

 Total 75 3,444 13.0 2.5 0.5 0.3 12.9 3.5 32.8

Western larch group

Western larch 25 3,684 7.4 4.0 0.7 0.4 14.8 6.3 33.6

 Total 25 3,684 7.4 4.0 0.7 0.4 14.8 6.3 33.6

Other western softwoods group

Limber pine 8 8,259 5.2 0.6 0.2 0.1 3.1 2.0 11.0

Whitebark pine 19 8,951 6.2 0.7 0.2 0.1 2.7 1.3 11.1

Western juniper 18 5,816 0.8 1.2 0.3 0.1 1.2 2.4 5.9

 Total 45 7,574 3.9 0.9 0.2 0.1 2.1 1.9 9.0

Elm-ash-cottonwood group

Cottonwood 6 3,671 2.8 4.2 0.7 0.1 2.3 1.6 11.8

 Total 6 3,671 2.8 4.2 0.7 0.1 2.3 1.6 11.8

Aspen-birch group

Aspen 65 6,446 4.2 2.1 0.3 0.1 6.5 4.9 18.1

Paper birch 3 2,411 1.9 1.9 0.2 0.2 17.6 10.2 31.9

 Total 68 6,268 4.1 2.1 0.3 0.1 7.0 5.2 18.7

Other hardwoods group

Other hardwoods 1 5,456 3.6 5.3 0.5 0.1 4.2 4.9 18.5

 Total 1 5,456 3.6 5.3 0.5 0.1 4.2 4.9 18.5

Woodland hardwoods group

Cercocarpus (mountain brush) 

woodland 16 6,882 1.1 0.3 0.2 0.1 2.0 3.6 7.2

Intermountain maple woodland 13 6,382 0.6 3.2 0.3 0.1 5.7 4.6 14.4

 Total 29 6,658 0.9 1.6 0.2 0.1 3.6 4.1 10.5

Nonstocked

Nonstocked 136 6,140 4.2 1.5 0.3 0.1 4.7 3.1 13.9

 Total 136 6,140 4.2 1.5 0.3 0.1 4.7 3.1 13.9

Totals 1,553 5,651 6.4 2.0 0.4 0.2 7.2 3.1 19.2
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 31

Fuel loadings by DWM component are essential for predicting fire behavior.

Table V also shows that the duff DWM component has the highest mean fuel loadings over all, followed by the CWD component and then the litter component.

Several forest types show some variation from this general trend. Also, fuel loading variation among forest types in the three FWD classes is not as great as in the

CWD, duff, and litter classes.

Surface fuel classifications of duff, litter, FWD, and CWD for estimating fire

effects were compiled from a wide variety of recent fuel sampling projects conducted across the contiguous United States (Lutes and others 2009). For each FIA

plot/condition, fuel loading ranges from these four classes were used to identify one of 21 potential fuel loading models (FLM) described by Lutes and others

(2009). Figure 15 displays the number of plot/conditions identified by FLM class

for the three survey units in Idaho. This shows that for this DWM dataset all of

the 21 possible FLM’s were identified, and the largest proportion of all the plot/

conditions (377) occurred in the class 11 FLM, followed by classes 21 (300 plot/

conditions) and 31 (287 plot/conditions). Class 11 was the most common FLM for

the southeastern and southwestern survey units; class 31 was the most common

FLM for the northern survey unit. Although these plot classifications are currently

under review, once they are objectively classified they can be used as inputs to

fire effects models to compute smoke emissions, fuel consumption, and carbon

released to the atmosphere.

Figure 15: Number of plot/conditions by fuel loading model (FLM) class and FIA survey unit, Idaho, 2006-2009.
32 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Structural diversity in terms of CWD diameters and decay classes are important criteria for wildlife habitat. IWFIA field crews identify one of five large-end

diameter classes for each P2 CWD piece tallied. This information may be critical

for wildlife species that use large-diameter logs for habitat. Figure 16 displays the

percentage of CWD pieces for decay classes 1 through 4 in each large-end diameter class by forest type. Although they contribute to biomass and carbon pools,

large-end diameter class is not recorded for pieces in decay-class 5 due to their

degree of decomposition. At 9 percent, the other western softwoods forest type

group (consisting of the whitebark pine, limber pine, and western juniper forest

types) has the highest percentage of CWD pieces in the 21.0-inch and greater class,

followed by the ponderosa pine forest type / group at 7 percent, the hemlock/Sitka

spruce forest type group (consisting of the western hemlock and western redcedar

forest types) at 5 percent, and the fir / spruce/ mountain hemlock group (consisting

of the Engelmann spruce, Engelmann spruce / subalpine fire, subalpine fir, grand

fir and mountain hemlock forest types) and nonstocked at 4 percent each. At 15.0

to 20.9 inches large-end diameter, the other western softwoods forest type group

again has the most at 16 percent, followed by the elm / ash / cottonwood group

(with only the cottonwood forest type) at 15 percent, although this percentage is

derived from a relatively small sample (34 CWD pieces on 4 plot/conditions). The

fir / spruce/ mountain hemlock group has 12 percent, and the ponderosa pine forest

type / group had 11 percent of their CWD pieces in the 15.0 to 20.9 inches largeend diameter class.

Figure 16: Percentage distribution of course woody debris (CWD) pieces (decay class 1-4) by large-end diameter class and 

forest type group, Idaho, cycle 2, subcycles 3-6, 2006-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 33

Another consideration other than size is the degree of decay of individual logs.

Decay classes can range from class 1, which are newly fallen trees with no decay,

to class 5, which still resemble a log but often blend into the duff and litter layers.

Figure 17 shows the percentage of CWD pieces by forest type and decay class. In

general, the wetter types have a higher percentage of CWD pieces in the advanced

decomposition classes, while drier types have a lower percentage.

The annual FIA system supports live and standing dead tree inventories but does

not include down dead trees as did some past periodic inventories. The current P3

DWM protocols and estimation procedures (Woodall and Monleon 2008) include

improvements such as population estimation, and are designed to capture some

important aspects that serve as a better surrogate for answering relevant questions

about the various components of down woody materials in forests. However, P3 is

a 1/16th sample of P2, and although it may be adequate at the regional or national

level, it is often inadequate for many DWM applications at the State level.

Although this analysis included only plot-level per acre estimates and analysis,

soon IWFIA will have population estimate capabilities for its regional P2 DWM

database. This will allow analyses of the impacts and implications of expanding

plot level information to the State. For example, table V shows that although the

western larch forest type in Idaho has over twice the total per acre DWM biomass

as the Douglas-fir type, the area of the Douglas-fir type is over 20 times that of

the western larch type (table 3). Once population estimates are factored in, the

Douglas-fir type will likely contain more total DWM biomass and carbon than

many of the types with high per acre estimates in Idaho.

Figure 17: Percentage distribution of course woody debris (CWD) pieces by decay class and forest type group, Idaho, 

cycle 2, subcycles 3-6, 2006-2009.
34 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

The Pacific Northwest FIA and IWFIA are jointly investigating a national P2

inventory version of DWM to support a more robust dataset for future fire fuel,

wildlife structure, and carbon assessments. These protocols should be complementary and compatible with the current regional P2 variations. As estimates of DWM

are improved and refined, along with FIA’s understory vegetation and standing

tree inventory, FIA will be better positioned for addressing estimates of total forest

biomass.

Soil Resources in Idaho’s Forests

Soils on the landscape are the product of five interacting soil forming factors.

These are parent material, climate, landscape position (topography), organisms

(vegetation, microbes, other soil organisms), and time (Jenny 1994). Many external forces can have a profound influence on forest soil condition and hence forest

health. These include agents of change or disturbances to apparent steady-state

conditions such as shifts in climate, fire, insect and disease activities, land use

activities, and land management actions.

The Soil Indicator of forest health was developed to assess the status and trend

of forest soil resources in the United States across all ecoregions, forest types,

and land ownership categories. For this report, data were analyzed and are being

reported by forest type groups. This forest type stratification not only reflects the

influence of forest vegetation on soil properties, but also the interaction of parent

material, climate, landscape position, and time with forest vegetation and soil organisms. A complete listing of mean soil properties in Idaho, organized by forest

Figure 18: Soil organic carbon stocks (Mg/ha) in the forest floor and 0-10 and 10-20 cm soil layers arranged by forest type 

groups in Idaho. The forest type groups are arranged left to right in order of increasing latitude, elevation, and precipitation with some overlap among forest types. The juniper group in Idaho includes Rocky Mountain juniper and western 

juniper. The spruce/fir group in Idaho includes grand fir, Engelmann spruce, subalpine fir, and mixed Engelmann spruce/

subalpine fir.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 35

type, can be found in appendix E. These are least-squares means generated by the

SAS GLMMIX data analysis software program. Some plots had a repeat visit so

the data are summarized by visit number (1 or 2) and by forest type. Plots visited

for the first Soil Indicator measurements were sampled in 2000, 2001, 2002, 2004,

2007, and 2008. Only a small subset of plots have been re-visited thus far in 2006,

2007, and 2009 so there is not yet enough data to run a valid repeated measures

analysis. Nevertheless, we report the data for the re-visited plots summarized by

forest type in the Soil Indicator core tables. Some of the key soil properties were

graphed by forest type group in Idaho and are highlighted in the discussion below.

Generally, soil moisture increases with elevation and latitude (associated with

cooler temperatures) and forest types tend to reflect this climatic gradient. When

expressed in terms of megagrams of carbon (C) per hectare of forest area, C stocks

generally increase with elevation and/or soil moisture storage (fig. 19). Soil nitrogen (N) stocks in cercocarpus woodland, cottonwood/aspen, and limber pine

forests in Idaho tend to be higher than those in other forest types (fig. 19). The

high soil N under cercocarpus in Idaho is based on only one plot, but these results

are similar to those in Utah (DeBlander and others 2010). High soil N stocks under cottonwood/aspen in Idaho mirror data from Utah and Colorado where higher

amounts of N are stored in aspen-dominated landscapes (DeBlander and others

2010; Thompson and others 2010). The high C and N stocks in limber pine are

from a single plot and may not be representative. This is far too small a sampling

to generalize findings for this forest type across the State as a whole.

Soils in drier areas such as soils under cercocarpus and juniper woodland tend

to be less weathered and have higher amounts of exchangeable base cations such

Figure 19: Soil organic nitrogen stocks (Mg/ha) in the forest floor and 0-10 and 10-20 cm soil layers arranged by forest type 

groups in Idaho. The forest types and type groups are arranged left to right in order of increasing latitude, elevation, and 

precipitation with some overlap among forest types. The juniper group in Idaho includes Rocky Mountain juniper and 

western juniper. The spruce/fir group in Idaho includes grand fir, Engelmann spruce, subalpine fir, and mixed Engelmann 

spruce/subalpine fir.
36 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

as sodium, potassium, magnesium, and calcium (figs. 20a and 20b). Acidic soils,

many of which are found in wetter, higher elevation environments (e.g., spruce/fir)

tend to have lower levels of exchangeable base cations and have measureable levels of exchangeable aluminum. In none of the plots sampled are soil exchangeable

aluminum levels high enough to pose a toxicity risk to tree roots given the ample

supply of exchangeable calcium. Exchangeable base cation concentrations are also

high under cottonwood/aspen forests.

Soil pH in drier calcareous soils tends to be near-neutral to alkaline (fig. 21

top) and such soils are found under cercocarpus woodland in Idaho. The lowest

pH soils are found under lodgepole pine and spruce/fir forests and these tend to

be only moderately acid as a whole in Idaho. Moderately acid soils often have

elevated levels of extractable manganese (fig. 21 middle). Although elevated levels of manganese present some toxicity risk to sensitive species, potentially toxic

levels of extractable manganese have yet to be established for most forest plant

species. In general, only about 3.4 percent of the 0-10 cm forest soil layers in the

Interior West contain extractable Mn levels greater than 100 mg/kg (Amacher and

Perry 2011). In Idaho, most of the forest soils with elevated levels of extractable

Mn are found under spruce/fir (mean extractable Mn = 35 mg/kg in 0-10 cm layer).

The lowest levels of extractable phosphorus by the Olsen method were found in

soils under cercocarpus woodland, whereas the highest levels were found under

cottonwood/aspen (fig. 21 bottom). The lower levels of extractable P in the calcareous soils reflect strong attenuation of plant-available P by the abundant calcium

minerals in these soils.

Figure 20a: Exchangeable cations (aluminum, sodium, magnesium, potassium, and calcium) in the 0-10 cm soil layer arranged 

by forest type groups in Idaho.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 37

Figure 20b: Exchangeable cations (aluminum, sodium, magnesium, potassium, and calcium) in the 10-20 cm soil 

layer arranged by forest type groups in Idaho.

Figure 21: Soil pH (top), 1 M NH4Cl-extractable 

manganese (middle), and Olsen (pH 8.5 0.5 M 

NaHCO3)-extractable phosphorus (bottom) in the 

0-10 cm soil layer arranged by forest type groups 

in Idaho. Whiskers represent standard error.
38 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Overall, soils under lodgepole pine in Idaho tended to have the least nitrogen

stocks, the lowest levels of exchangeable bases, and the lowest pH. This probably

reflects the ability of the widely distributed lodgepole species to occupy lower fertility soils, whereas many other species prefer richer deeper soils. Throughout the

Interior West as a whole and in Idaho, aspen, for example, tends to occupy deeper,

richer, wetter soils and is associated with sites with higher nitrogen and potassium

reserves, near-neutral pH levels, and a general absence of exchangeable aluminum

(DeBlander and others 2010).

Snags as Wildlife Habitat

Standing dead trees (snags) provide important habitat in the forested ecosystems of Idaho. There are many organisms that utilize snags at some point in their

life history. These include, but are not limited to, bacteria, fungi, insects, rodents,

cavity-nesting birds, bats, raptors, mustelids, and black bears. The height, diameter, and decay status of a standing dead tree are some of the important attributes

for species that use snags as a nesting, roosting, or den site. Individual tree data

collected by FIA field crews allow for population-level analysis of the availability

of individual snags that meet criteria important to wildlife.

Cavity-nesting birds in Idaho are especially dependent on snags for both nesting and foraging activities. There are a handful of bird species that act as primary

excavators of nest sites. 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 nesting birds. Secondary cavity-nesters do not

excavate their own nest sites and are dependent on primary excavators for their

cavities. The suitability of an old cavity for a secondary nester often depends on

the species of primary excavator that created it. Here we present data reflecting the

number of snags in Idaho that are suitable for three important primary excavators.

These birds provide the bulk of cavities for secondary nesters in Idaho. The Hairy

Woodpecker (Picoides villosus), Red-naped Sapsucker (Sphyrapicus nuchalis),

and Northern Flicker (Colaptes auratus) create different sized openings and cavities and are also relatively abundant and wide spread throughout the different forest types of Idaho. Therefore they provide suitable nest sites for a wide variety of

secondary nesting species. The distribution of suitable snags by stand-age is also

presented. Suitability is based on mean tree diameters found to be used by these

birds (Flack 1976; McClelland and others 1979; Dobkin and others 1995; Martin

and others 2004).

There are almost 283 million snags in Idaho that meet the size preferences of

the Hairy Woodpecker (≥25cm (9.8 in.) d.b.h). The most abundant tree species

contributing to these bird’s nesting sites are Douglas-fir (80.1 million snags), subalpine fir (59.1 million), and lodgepole pine (53.8 million) (fig. 22). These snags

are predominately found in the Douglas-fir, subalpine fir, and non-stocked forest

types. Nearly 167 million snags meet the diameter preferences of the Red-naped

Sapsucker (≥31cm (12.2 in.) d.b.h.). Douglas-fir, subalpine fir and lodgepole pine

again contribute the majority of these snags at 58.6, 31.9, and 20.3 million snags

respectively. The forest types where most of these snags can be found are Douglasfir, non-stocked, and subalpine fir. Potential Northern Flicker snags (≥35cm

(13.8 in.) d.b.h.) are found in the same forest types as the two aforementioned bird

species. The tree species that comprise most of the suitable snag population for

this species are Douglas-fir (46.6 million), subalpine fir (20.7 million), and grand

fir (10.4 million). The non-stocked forest type often includes areas disturbed by
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 39

wildfire, disease, and insect infestations. These types of stands account for the high

number of snags in this forest type.

Figure 23 shows the distribution of snags ≥35cm (13.8 in.) d.b.h. by stand-age.

These snags are large enough to accommodate all three species of cavity excavators discussed here. For most forest type groups, the largest percentage of suitable

snags for all three birds is found in the 51 to 100 and 101 to 151 age-classes. The

zero age-class holds a large amount of suitable snags due to the large amount

of disturbed forests in the non-stocked forest type. Another notable exception to

the general age-class distribution is the aspen/ birch group. Aspen forests are particularly important for some primary and secondary nesting birds because of the

relationship of diseased aspen, primary excavators, and secondary nesters (Hart

and Hart 2001). Diseased trees provide a relatively soft substrate for primary excavators to build their nest cavities in. The secondary nesters then occupy many

of these cavities in subsequent years. Few aspen trees live past 100 years in Idaho.

Almost all (91 percent) snags found in aspen forests are found in the 1 to 50 year

age-class.

Variables other than snag dimensions and numbers need to be considered when

predicting suitable wildlife habitat for forest-dwelling species. Proximity to forest

edge and stand 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. FIA data can address many of these factors and there are current efforts

to build predictive models for these species by using data collected by our crews.

These models can be valuable tools for Federal and State land managers; at least

92 percent of the forests in Idaho containing suitable snags occur on public lands.

Figure 22: Number of snags meeting the preferences of three important cavity-excavating birds by tree species, Idaho, 

2004-2009.
40 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Idaho Timber Harvest and Forest Products

The University of Montana Bureau of Business and Economic Research

(BBER), in cooperation with the Interior West Forest Inventory and Analysis

program, conducts periodic censuses of Idaho’s timber processing facilities. The

BBER conducted a statewide census of primary forest products facilities in Idaho

for calendar year 2006 (Brandt and others 2011). This report updates key aspects

of the 2006 census based on annual assessments and industry outlooks coordinated

by the BBER in conjunction with the University of Idaho Forest Products Program

in the College of Natural Resources.

Primary forest products facilities are firms that process timber into manufactured products such as lumber, and facilities such as pulp and paper mills and particleboard board plants that use wood fiber residue directly from timber processors.

A total of 97 forest products plants were identified as active in Idaho during 2006,

including 35 sawmills, 24 log home facilities, 16 Post, pole, and log furniture

manufacturers, 12 residue related products facilities, 7 cedar product mills, and 3

plywood/veneer plants.

A strong economy, low interest rates, easy access to credit, and real estate speculation fostered more than two million U.S. housing starts in 2005 and record annual lumber consumption from 2003 to 2005. The year of the most recent census

of the Idaho’s forest products industry, 2006, was the beginning of what has been

the most extended and severe economic downturn since the Great Depression. U.S.

housing markets in 2006 dropped modestly to 1.8 million starts in 2006, and then

with the onset of an official recession in 2007, the 2008 global financial crisis, and

Figure 23: Number of snags meeting the preferences of three important cavity-excavating birds by stand-age class and 

forest type group, Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 41

further weakening of the U.S. economy in 2009, housing starts fell to a post-World

War II record low of 554,000, improving only to 587,000 in 2010.

With much weaker markets, wood product prices and outputs of Idaho’s wood

and paper products industry fell dramatically. In 2008, 2009, and 2010, virtually

every major mill suffered curtailments and several large and numerous small mills

closed permanently. Idaho mills’ capacity to process timber dropped approximately 20 percent between 2006 and 2010, to just over one billion board feet, Scribner,

while capacity utilization fell from nearly 80 percent during 2003 to an estimated

55 percent during 2010.

Wood and paper product output value dropped from $2 billion in 2004 to $1.8

billion in 2006 to under $1.5 billion in 2009 and 2010. The trend in lumber produced and volume of timber harvested in Idaho also reflects the current condition

of the forest products industry. Lumber production, the major output of Idaho’s

industry and the component most impacted by weak housing markets, fell to 1,105

million board feet (MMBF) lumber tally in 2009 and 1,258 MMBF in 2010, the

lowest 2 years on record since WWII (fig. 24).

Timber harvest for 2010 was 830 MMBF (Scribner), up about 10 percent from

2009 and approximately equal to 2008; the annual harvest each year for 2008-2010

were the three lowest harvest totals in Idaho since the second World War (fig. 25).

Timber harvest on private lands accounted for 57 percent of the volume in 2010,

down from 75 percent in 2006, and nearly one-third of Idaho’s total harvest came

from State lands in 2010, up from 18 percent in 2006. The share of harvest from

Federal lands increased from 7 percent in 2006 to 11 percent in 2010. The number

of forest industry workers declined by 4,000 workers since the stronger markets of

mid-decade, dropping from approximately 14,500 to an estimated 10,500 in 2010.

Figure 24: Idaho lumber production, 1947-2010 (sources: Bureau of Business and Economic Research, The University 

of Montana-Missoula; USDA Forest Service Region One, Missoula, Montana; Western Wood Products Association).
42 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Issues in Idaho’s Forests

Decline of Whitebark Pine

Whitebark pine has become recognized as an important component of highelevation ecosystems in western North America. Its periodic crops of large wingless seeds provide a major food source for several species of birds and mammals

including the black bear and grizzly bear (Schmidt and McDonald 1990). Wildlife

biologists have noted that for several months after production of a large whitebark

pine cone crop, bears concentrate their feeding on cone caches made by squirrels

and tend to stay away from lower elevation encounters with humans and their habituations (Kendall 1980). Whitebark pine aids in the protection of watersheds by

stabilizing soil and rock on the harshest sites and by catching and retaining snowpack. (Arno and Hoff 1989).

Compared to other conifer species in Idaho, whitebark pine is relatively uncommon. Whitebark pine forest types comprise about 297 thousand acres in Idaho or

about 1.4 percent of total forest area in the State. The number of all live whitebark

pine trees 1.0 inches d.b.h. and larger totals 190 million trees in Idaho or about

2.4 percent of all live trees in the State.

In many areas in the West, whitebark pine stands have experienced heavy mortality (Arno 1986). The principal agents named in the decline are the white pine

Figure 25: Idaho timber harvest by ownership, Idaho, 1947-2010 (sources: Bureau of Business and Economic Research, 

The University of Montana-Missoula; USDA Forest Service Region One, Missoula, Montana).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 43

blister rust (Cronartium ribicola), the mountain pine beetle (Dendroctonus ponderosae), and forest succession by shade-tolerant trees in the absence of fire.

To address the decline of whitebark pine in Idaho, an analysis of long-term

trends was performed using remeasurement data from permanently established

FIA plots. In the previous periodic inventory of Idaho, which occurred between

1990 and 1997, variable radius plots were the samples used to conduct the field inventory. When the annual inventory began in 2004, IWFIA changed the sampling

design to the fixed-radius national mapped plot design. In addition to the initial

establishment of the mapped plot, field crews were instructed to relocate and remeasure trees tallied on the previously established variable-radius plot. All trees

measured in the previous inventory (time 1) were accounted for and current status

recorded (live, dead, cut) in the current inventory (time 2). This remeasurement

and accounting for trees on previously established plots provides an accurate measure of growth, removal, and mortality rates since the status of trees are known at

both points in time. The procedures used to remeasure the previous variable-radius

plot and a description of the plot layout is described in U.S. Forest Service 2011.

Remeasurement of permanent FIA plots can produce estimates of change that

quantify the net change in inventory between two points in time. For this analysis,

mean basal area per acre of whitebark pines 5.0 inches d.b.h. and larger was the

attribute of interest. The following components were generated for the analysis:

•	 Initial Inventory—Basal area/acre of live whitebark pines 5.0 inches d.b.h. and

larger measured at the previous visit.

•	 Survivor growth—Change in basal area/acre of live whitebark pine trees 5 inches d.b.h. and larger measured at the previous visit and the basal area/acre of live

whitebark pine trees 5 inches d.b.h. and larger measured at the second visit.

•	 Ingrowth—Basal area/acre of live whitebark pine trees 5 inches d.b.h. and larger at time of second visit but were less than 5.0 inches d.b.h. at time of previous

visit (trees that grew on to the inventory during the remeasurement period).

•	 Mortality—Basal area/acre of live whitebark pine trees 5 inches d.b.h. and larger measured at the previous visit that were dead due to natural causes at time of

second visit.

•	 Removals—Basal area/acre of live whitebark pine trees 5 inches d.b.h. and larger measured at the previous visit that were cut at time of second visit.

•	 Terminal Inventory—Basal area/acre of live whitebark pines 5.0 inches d.b.h.

and larger measured at the second or current visit.

For this analysis, only remeasured plots where at least one live whitebark pine

5.0 inches d.b.h. and larger measured in the initial inventory qualified as eligible

for this analysis. A total of 50 remeasured plots in Idaho met the criteria. The initial

inventory measurement years ranged from 1990 to 1997. The terminal inventory

measurement years ranged from 2004 to 2009. Plots measured prior to 1993 were

on non-National Forest Systems (NFS) land and those measured after 1992 were

on NFS land. The average interval between plot measurements was 13.5 years.

The procedure used to estimate the basal area per acre for the six components is

described in Beers and Miller (1964).

Mean basal area per acre of whitebark pine for the six change components are

illustrated in figure 26. Mean basal area per acre of whitebark pine in Idaho decreased 25 percent or by about 2.3 percent per year. Mortality reduced the estimate

of initial inventory by 32 percent. Mortality rate of whitebark pine averaged 3

percent per year. The leading cause of death of the whitebark pines classified as
44 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

mortality was insects, which accounted for 32 percent of the trees that died during

the remeasurement interval. The second leading cause of death was attributed to

unknown causes at 12 percent. Fire accounted for 11 percent of the whitebark pine

mortality.

These results indicate a very significant decline in live basal area of whitebark

pine. The annual level of mortality is greatly outpacing the combined annual basal

area growth of survivor trees and ingrowth trees. Similar studies conducted in the

early 1970s in western Montana also indicated significant basal area reductions

in whitebark pine due to heavy mortality (Keane and Arno 1993). Figure 27 illustrates the numbers of live whitebark pine trees by diameter class. Numbers of 2-

and 4-inch whitebark pines comprise almost 70 percent of all live whitebark pines

in Idaho. The high proportion of sapling-size trees might suggest enough regeneration is occurring to offset losses due to mortality in the larger diameter classes.

However, blister rust can cause mortality and top kill in whitebark pine seedlings

and saplings resulting in fewer saplings reaching maturity. Blister rust incidence

is particularly high in northern Idaho (Kegley and others 2011). Whitebark pine

is a slow-growing tree. Depending on site conditions, the tree can attain small to

moderately large size after 250 or more years, but may start producing cones as

early as 70 years old.

This analysis underscores the need to use broad-scale inventory data for monitoring trends in whitebark pine. The power to detect significant effects related to

whitebark pine mortality and other parameters of interest will increase substantially with estimates derived from the remeasurement (paired) plots that will be

available as the IWFIA region begins to accumulate data from remeasured plots.

Figure 26: Periodic estimates of initial inventory, terminal inventory, and change components for whitebark pine in 

Idaho expressed as mean basal area per acre for remeasured plots.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 45

Aspen Mortality

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 2000 feet in

northern Idaho to 11,700 feet in Colorado. It is also found on a wide range of sites,

and occurs 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, it also reproduces infrequently by seeding, relying mostly on root sprouting for reproduction.

However, aspen responds well to fire and cutting, and it is able to dominate sites

for many years following severe disturbance. In addition, there is some evidence

that aspen is able to persist in conifer-dominated forests by exploiting gaps in

the 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 where it occurs spontaneously or

after disturbance (e.g., Hessl and Graumlich 2002). The lack of disturbance allows

conifers to gain dominance where they are present, and in pure aspen stands, consumption 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 an impact on aspen and other forest types (e.g., Shaw and others 2005;

Thompson 2009). Drought appears to have contributed to mortality in many lowelevation stands (Worrall and others 2008), and in some of these regeneration is

either lacking or suppressed by herbivores.

Figure 27: Numbers of live whitebark pines by diameter class in Idaho, 2004-2009.
46 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Johnson (1994) suggested that the acreage of aspen-dominated stands had declined as much as 46 percent in Arizona since the 1960s, with most of these acres

becoming dominated by mixed conifer forest types. Bartos (2001) suggested that

similar changes—aspen acres decreasing by 61 percent—had occurred in Idaho.

These assessments of “lost” aspen acres were based on the assumption that forested

acres with a minority aspen component were, at one time in the recent past, dominated by aspen in pure or nearly pure stands. This assumption may not be reasonable

because there are many situations where aspen may persist normally as a minorstand

component.

It is not possible to estimate trends in the aspen forests of Idaho with great certainty because of the differences between the coverage of periodic and annual inventories. However, it is possible to make a limited set of comparisons when looking at

certain characteristics that are indicative of aspen status, such as the proportion of

aspen acreage to total forest acreage, number of acres with only dead aspen present,

and number of acres with aspen reproduction present.

Current inventory data show that there are approximately 708,000 acres of the

aspen forest type in Idaho, as compared to nearly 532,000 acres found during the

previous inventory. When considering all acres where aspen is present, the current

inventory data show that at least one live aspen stem is present on over 1.43 million

acres, while the previous inventory showed live aspen present on just over 1.33 million acres.

Statistics on live trees may overlook “relict” aspen stands, and both inventories

show that some stands had only dead aspen present at the time of inventory. The

1990s periodic inventory showed that only dead aspen 1.0 inch diameter and greater

were found on approximately 64,000 acres, or about 4.6 percent of all acres with aspen present. The current inventory shows an apparent increase to over 101,000 acres,

or about 6.6 percent of all acres with aspen present. However, when seedling-sized

trees are taken into account the area with only dead aspen decreases substantially,

and there are many more acres where only aspen seedlings (or suckers) are recorded.

Of the plots where aspen is only found as seedlings or suckers, disturbances such

as fire are frequently recorded (see the “Fire in Idaho Forests” section). The actual

trends—whether the marginal aspen presence represents new establishment or fading remnants—will only be addressed through continuous monitoring.

Another way to compare the previous and current inventories is to normalize data

on a common basis—for example, basal area per acre. During the 1990s periodic

inventory in aspen-dominated stands (aspen forest type), the average basal area per

acre of all aspen (live and standing dead) was just over 60 square feet per acre,

with 49 square feet per acre in live aspen. In the current annual inventory, aspendominated stands averaged lessthan 42 square feet of live and dead basal aspen area,

with just under 35 square feet per acre of live aspen. The results are similar for all

stands with an aspen component of trees at least 1 inch diameter. Total aspen basal

area in these stands averaged just under 34 square feet of basal area in the periodic

inventory, with about 27 square feet of basal area in live aspen. As with the aspendominated acres, the numbers were lower in the annual inventory: slightly more than

26 square feet per acre of live and dead aspen, and slightly more than 21 square feet

of live aspen. These data suggest that live aspen basal area has fallen approximately

30 percent on a per-acre basis since the periodic inventory. However, it is not yet

possible to tell if this is a real decrease (for example, caused by successional changes

and disturbances) or an apparent increase possibly caused by capturing a high proportion of regenerating aspen acres in the annual inventory that were not captured in

the periodic inventory.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 47

In contrast with apparent trends in live aspen stocking, mortality rates do not

appear to be increasing in recent years, at least in comparison to the mortality

rates observed during the periodic inventory. Mortality is expressed here as the

proportion of basal area estimated to have died in the 5 years prior to the plot visit.

During the 1990s periodic inventory, mortality was estimated at almost 13 percent

in aspen-dominated stands and almost 14 percent in stands with an aspen component. This equates to an average annual mortality of about 2.6 percent. During the

annual inventory, mortality was estimated at almost 5 percent in aspen-dominated

stands and 5 percent in stands with an aspen component. This equates to an average annual mortality of about 1.0 percent. Because the annual inventory is spatially

unbiased over time, it is possible to look at year-by-year mortality estimates for

possible trends. Figure 28 shows the mortality estimates for annual inventory years

2004-2009. Although the annual trend data might be somewhat noisy due to small

sample size within any given year, it appears that there might have been some elevated mortality just prior to the initiation of the annual inventory. During the past

few years of the inventory, mortality rates appear to have settled at relatively low

levels, however, suggesting that mortality rate has not been increasing substantially, and may actually be decreasing.

Comparisons between the mid-1990s periodic inventory results and the current

annual inventory data in Idaho give somewhat conflicting results, so aspen trends

are difficult to interpret at this point in the inventory. Total acreage with aspen

present appears to be somewhat higher than in the 1990s, but the aspen component

appears to have decreased when considered on a basal area per acre basis. Several

disturbance agents, including fire and drought, have apparently reduced aspen basal area. However, there are a substantial number of plots with aspen reproduction

Figure 28: Estimated 5-year mortality rates of aspen for individual measurement years and average 5-year mortality, 

Idaho, 2004-2009.
48 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

present. On many of these plots there are no large, standing live or dead aspen, so

it is difficult to ascertain whether these plots are capturing re-occupation of the

sites by aspen or expansion of aspen into other forest types. However, continued

monitoring of these plots in the future will tell whether or not the young aspen

reproduction is able to persist.

There have been many studies that have shown aspen to be in decline at local

scales (e.g., Bartos and Campbell 1998; Di Orio and others 2005; Worrall and others 2008), while other analyses have shown increased dominance of aspen in some

landscapes (Kulakowski and others 2004). It is not surprising that studies documenting loss are more numerous, because unexplained or unexpectedly high mortality events tend to attract the attention of managers, researchers, and the public.

Because these changes are evident to a wide range of observers, there is a tendency

to extrapolate local conditions to larger areas. Aspen is found in many forest types

with a wide variety of associate tree species, and the characteristics of aspen-dominated stands and stands with aspen as a minor component vary considerably over

the range of the species. This makes generalization difficult. In addition, local or

regional trends may differ from those of the population as a whole, because agents

like drought and fire are not evenly distributed over the landscape. However, with

continued monitoring under the annual inventory system, FIA will be able to assess regional- and population-scale trends in aspen.

Mountain Pine Beetle

High tree mortality rates associated with mountain pine beetle infestations have

become a serious issue in many western forests. Since the primary host of mountain pine beetle is lodgepole pine, and lodgepole pine comprises a significant component of many western North American forests, recent epidemics of this insect

have raised significant concerns about the health, stand structure, and composition

of lodgepole pine stands.

The mountain pine beetle is a native insect to western pine forests in North

America and innocuous populations are almost always present in forests. Transition

to epidemic populations is a function of the beetle’s capacity to locate, colonize,

and reproduce within suitable host trees in a weather pattern conducive to overwintering survival, emergence, and dispersal (Carroll and Safranyik 2004). The reasons behind the recent outbreaks have received considerable discussion. Most bark

beetles prefer to invade trees that are in poor physiological condition (Rudinsky

1962). Temperature is known to influence insect outbreaks, especially species such

as the mountain pine beetle (Amman 1973). The effect of global warming is believed by some researchers to be a contributing factor in the severity of mountain

pine beetle infestations (Logan and others 2003). Another significant factor is the

presence of large areas of lodgepole pine stands comprised of ideal host trees homogeneous in age, composition, and structure.

Figure 29 illustrates the average annual volume of lodgepole trees killed by

insects by measurement year in Idaho. The estimates in figure 27 illustrate a moving average trend that accumulates information from successive annual inventory

measurements. The assumption is that most of the lodgepole classified as mortality and assigned a cause of death of insects is due to the mountain pine beetle. It

is clearly evident that a pronounced upward trend has occurred during the 6 years

of annual inventories in Idaho. As of 2009, the average annual volume of insectkilled lodgepole pines is 108 million cubic feet, which is double the 54 million

cubic feet recorded in 2004.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 49

Phase 2 Damage

The Interior West FIA program has used a regionally defined damage protocol

for most of the periodic and annual inventories since 1981. Throughout this time,

the protocol has remained consistent, with only a few modifications to the damage

categories. Damages are assigned only to live trees, in contrast to mortality agents,

which are only assigned to recently dead trees. Not all damaging agents are potential mortality agents, so there is only partial overlap in the two agent lists.

FIA currently has 50 damage codes representing a wide range of biotic, abiotic,

and anthropogenic agents. Up to three damage agents may be assigned to a tree.

However, less than a third of damaged trees have more than one agent assigned,

and less than a 25 percent of trees with two damage agents will have a third agent

assigned.

The protocol is based on a threshold system, where damage is only recorded if

it is considered “serious.” Although this is somewhat subjective, the general rules

are that damage should be recorded when it will:

1. Prevent the tree from living to maturity, or surviving 10 more years if already

mature.

2. Prevent the tree from producing marketable products.

3. Reduce (or has seriously reduced) the quality of the tree’s products.

These rules roughly correspond to two main categories of damaging agents.

Agents that are likely to prevent a tree from living to maturity or surviving for 10

years after the inventory date tend to be those related to insects, disease, fire, and

atmospheric effects (drought, flooding, wind, etc.), whereas agents that preclude

or reduce a tree’s merchantability are more likely to be problems with form, such

Figure 29: Moving average estimate of average annual volume of lodgepole pine killed by insects by measurement 

years, Idaho, 2004-2009.
50 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

as forks, broken tops, or logging scars. The latter group may or may not affected

a tree’s survival. Therefore, not all trees with damages recorded are expected to

die, and some of those with poor merchantability may live to typical upper ages

for their species. A nationally consistent protocol for non-lethal damage to trees is

scheduled to be implemented by the FIA program in 2013. A majority of the damage categories used in the national protocol crosswalk directly with the Interior

West regional categories, ensuring that it will be possible to track trends in damaging agents over time.

Because earlier inventories of Idaho were done under the periodic system and

parts of those inventories were spread over a wide range of years, it is difficult to

compare earlier results to the current annual inventory. In order to keep the data as

comparable as possible, damages are described as proportions of the trees tallied

during the different time periods, that is, they are not expanded to make population-scale estimates.

There were 71,137 live trees tallied during the Idaho periodic inventory years

(1981 to 2002), and 51,359 live trees tallied during the first 6 years of annual inventory (2004 to 2009). During the periodic inventories, 37.0 percent of trees were

assigned one damage agent, 7.8 percent had two agents, and 1.2 percent had three.

A smaller proportion of live trees (27.9%) were assigned one damage agent during the annual inventory, although the proportions of trees with secondary (7.3%)

and tertiary (1.4%) damage agents were comparable to the periodic inventory proportions. The apparent reduction in the frequency of primary damage was spread

across all major agent categories, with only the insect and fire categories showing

increases (table VI).

Damage agents related to merchantability accounted for the majority of primary

damage agents, with diseases being the second most frequently recorded damage

(table VI). The lower rate of assignment of form damages accounted for about half

of the overall decrease in primary damage agents. The next most frequent damage

category was diseases, with the most frequently recorded agents within this category being stem and butt rots, cankers, and dwarf mistletoes. It should be noted

that dwarf mistletoe is recorded for all infected trees using a separate variable,

but only trees with a dwarf mistletoe rating (DMR) (Hawksworth 1977) of 4 to 6

are considered as “serious” for the purpose of damage agent assignment. Notable

Table VI—Distribution of primary damage agents by agent group, Idaho 

periodic (1981-2002) and annual (2004-2009) inventories. 

Damage agent group (codes) Periodic Annual

Percent

No Damage (0) 63.00 72.10

Insects (10-16) 0.80 1.30

Diseases (20-29) 6.70 4.20

Fire (30-31) 0.40 0.50

Animals (40-48) 0.30 0.20

Atmosphere (50-59) 1.00 0.50

Suppression (61) 1.50 0.20

Form (71-79) 25.90 20.60

Human (80-85) 0.20 0.20

Unknown / Unidentified (70) 0.30 0.20
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 51

damage agents within the insect category were bark beetles (0.45% in periodic and

0.52% in annual) and defoliators (0.09% in periodic and 0.48% in annual). Within

the animal category, the majority of damage was caused by big game (0.13% in

periodic and 0.09% in annual), and within the atmosphere category, the most common sources of damage were snow (0.31% in periodic and 0.06% in annual) and

frost (0.49% in periodic and 0.32% in annual).

While it is difficult to compare changes in damage rates between periodic and

annual inventories with statistical certainty, it is possible to consider some of the

expected patterns in comparison to the data. For example, it may seem reasonable

that the decreases in form, suppression, and disease damages could be the result of

fuel reduction and other silvicultural activities, which would tend to target trees in

these categories disproportionally. However, this cannot be known with certainty

until remeasurement occurs under the annual inventory system. On the other hand,

the apparent increases in the insect categories of bark beetles and defoliators are

consistent with aerial surveys and other information sources that show these agents

have been on the increase in recent years. Damage from bark beetles shows a moderate increase compared to the known increase in mortality in many conifers (see

the “Issues in Idaho’s Forests” section of this document), but this is not surprising

given that FIA crews are more likely to encounter a bark beetle-infested tree when

it is dead, and not during the brief period when it is live and heavily infested. In the

typical situation, bark beetles would be assigned as the mortality agent of a dead

tree as opposed to the damaging agent of a live tree.

The comparison of damage frequency over time also illustrates a key difference between periodic and annual inventory data. Periodic data are intended to be

taken together as a whole inventory, even though the plots may be spread out over

several years. During a periodic inventory, it is not uncommon for the plots done

in a given year to be concentrated in a particular part of the State. As a result, there

is geographic bias when measurement years are considered separately. Under annual inventory, the plots are geographically distributed every year and there is no

geographic bias. The end result is that apparent trend within the periodic inventory

may actually be the result of geographic bias. Under annual inventory, any trend

over time may be more reliably interpreted as real. This is apparent when total

damage frequency is plotted by measurement year (fig. 30). Note that the proportion of damaged trees varies widely over the periodic inventory years (1990 to

2002), but remains relatively consistent (but with a slightly declining trend) over

the annual inventory years (2004 to 2009). The variation among periodic years is

likely due to plots being located in areas of relatively high or low damage (e.g.,

recent fires, areas with snow damage, or localized insect outbreaks) in any given

year.

As noted above, assignment of damage does not necessarily imply impending

death of a tree. The types of form damages most frequently recorded—lean, forks

below or above merchantable top, broken or dead tops, and crook/sweep/taper—

are unlikely to result in mortality, so few of those in the form damage group should

be expected to die. If we assume that the form damage group is considered non-lethal and all other agents combined are considered as potentially lethal within a 10-

year window, the numbers are probably within what would be expected for normal

stand development. For example, form-damaged and undamaged trees account for

92.7% of all tally trees. Over a 10-year window this equates to 0.73 percent on an

annual basis, which can easily be accounted for under normal stand dynamics. Of

course, the damaged trees that are expected to die are in addition to the mortality

trees encountered during the most recent plot visits, and mortality is elevated in
52 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

many species. This may suggest that damage frequencies are not greatly affected

by elevated mortality rates, because for many agents the transition from “healthy”

to dead may occur relatively quickly. It is possible that elevated mortality could

partly explain the apparent decrease in many agent categories, because the damage variables identify trees that are predisposed to early mortality. Although this is

the underlying assumption, it will not be conclusively demonstrable until annual

remeasurement occurs.

Old Forests

An important aspect in managing for ecologically sustainable and diverse ecosystems is the maintenance of forest stands representing the full range of forest

succession. The oldest stages of this range are of particular interest to forest managers. Historically, these last stages of forest growth have been difficult to define or

describe. The terminology has included late seral, climax, mature, overmature, and

old growth, among others. Generally, as forests mature, stand structure changes in

ways that are important to ecological and habitat function. Some of the structural

indicators proposed include the size (diameter) and age of the oldest trees, the

number of large old trees per acre, and overall stand density (Green and others

1992; Hamilton 1993; Fiedler and others 2007). Standardized definitions are difficult because the final structure and age of a given forest stand depends on many

biological and physical components: climate and geology, dominant tree species,

Figure 30: Variation of proportion of damage trees recorded by measurement year, 1990-2009. Years 1990 to 2002 were 

part of the Idaho periodic inventory; 2004 to 2009 were measured as part of the annual inventory system.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 53

fire regimes, and others (Kaufmann and others 2007; Vosick and others 2007). The

forest structural indicators used to assess old forests will change with changes in

these components. In addition, the characteristics of old growth can change with

the scale of observation, from patches to stands and landscapes (Kaufmann and

others 2007).

One method of assessing old forests is simply to use the stand age of 150 years

or greater as a surrogate for old forests. Another method uses a minimum density

of trees with individual ages of at least 150 years. These approaches were recently

used in assessing old forests in Utah (DeBlander and others 2010). These same

criteria, as well as a minimum tree diameter and a minimum density (basal area per

acre), were used for this analysis. It should be noted that these criteria are not those

used by any of Idaho’s National Forests to define old forest.

Almost 12 percent (2.5 million acres) of Idaho’s forest land has a stand age of

150 years or older. Figure 31 shows this distribution by forest type. The Douglasfir and subalpine fir types have the most acres 150 years and greater based on stand

age, while the highest proportions are found in the limber pine (72%), whitebark

pine (61%), and Engelmann spruce (33%) types. Common types with lower than

average proportions of area with stand age of at least 150 years include lodgepole

pine (5%) and grand fir (4%). The western larch type had not only the least acres

with a stand age of at least 150 years; it also had the smallest proportion of any

type with older stands (2%).

Stand age is generally calculated as the mean age of trees from the stand-size

class that has the plurality of stocking. This tends to diminish the significance of

older trees by averaging tree ages of both old and young trees. Another method

Figure 31: Total area of forest land and area of forest land with stand age of 150 years or more by forest type 

(types with stand age of 150 years or more), Idaho, 2004-2009.
54 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

of using FIA data for describing stand structure is by calculating the number of

trees per acre that are at least 150 years old, based on sample core trees. Core ages

were adjusted, based on the height of the core, and assigned to other trees of the

same species and diameter class; essentially the same procedure as used in assigning stand age. Area of old forest using thresholds of 10 trees per acre and 5 trees

per acre at least 150 years old were determined in order to illustrate differences

in methods for assessing old forests. In addition, since most sources recommend

minimum stand densities and tree diameters to define old forest, 80 square feet per

acre of total live basal area and 18 inches diameter (d.b.h./d.r.c.) were somewhat

arbitrarily chosen; again to illustrate differences in assessment methods. Area of

old forest meeting this minimum density and with either 5 or 10 trees per acre

meeting both the age (150 years) and diameter (18 inches) thresholds was also determined. The area of forest land meeting four combinations of criteria are shown

by forest type in figure 32.

While an estimated 12 percent (2.5 million acres) of Idaho’s forests are “old”

based on stand age alone, by using a minimum tree age criteria, 24 percent (5.1 million acres) of all forest land acreage in Idaho could qualify as old forest at 10 old

trees per acre, and 32 percent at 5 old trees per acre. This increase in acreage is

reflected differently by forest type; notice the very large increase in grand fir compared to the smaller change in Engelmann spruce. One drawback of using only

tree age criteria is that only one or two trees measured on an FIA plot expand to

over five or ten trees per acre. Therefore, very sparse stands with only old trees

may meet these criteria: very unproductive sites, like scree slopes, or seed-tree

Figure 32: Area of old forest stand structure by forest type and stand age method (types with old forest structure by any 

method), Idaho, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 55

cuts. This is illustrated by the inclusion of nonstocked stands meeting the tree age

criteria, at both 5 and 10 old trees per acre. If we include a basal area requirement,

along with adding a diameter to the tree age requirement, the sparse stands can be

eliminated.

With all three criteria, 12 percent (2.6 million acres) of Idaho forest land meet

the old forest criteria at 10 large old trees per acre and 19 percent at 5 large old trees

per acre. Although the acreage for 10 large and old trees per acre with at least 80

square feet per acre of basal area of all live trees is similar to the area meeting the

stand age requirement, the overlap between the two is just over 50 percent. That is,

about 1.3 million acres of forest land meet both criteria. Comparing stand age with

the 10 trees per acre age/diameter/basal area criteria by forest type, some types

show little overall difference (Douglas-fir and Engelmann spruce). Other types

have relatively more area meeting the age/diameter/basal area minima (grand fir

and western redcedar), while others have less (whitebark pine and lodgepole pine).

Notice that no acres of the nonstocked forest type meet the age/diameter/basal area

criteria.

The large differences between the area meeting different criteria by forest type

illustrate the need for individual definitions for determining old forest structure.

Some tree species are longer lived, or typically grow larger than others. Life histories of different species may affect how much area would be expected to be dominated by large, old trees of a given species: a larger proportion of old forest might

be expected in Engelmann spruce than in lodgepole pine, for example.

As discussed in the previous section on Quality Assurance Analysis, tree age is

an important but sometimes difficult variable to collect accurately. This analysis

depended on individual tree ages as well as stand ages, which are derived from

them. An option for future research is that the FIA database could be used to validate or even help to establish surrogate measurements to define old forest structure

in different regions, for different forest types, and under different growth potential conditions, so that FIA data could be more effectively used to assess various

old forest conditions. Since the surrogates used to categorize old forest structure

can give varying results for different forest types it is important to align size/age

structure definitions with the methods or variables intended for monitoring them.

It is also important that the desired measure for monitoring be able to address the

full range of size/age structural categories included in the definitions, in order that

categories are mutually exclusive and cumulative.

Fire in Idaho Forests

Fire is an important disturbance in Idaho forests. In some forest types, like ponderosa pine, fire can maintain open stands and promote grasses and forbs growth

in the understory. For other forest types, such as aspen and lodgepole pine, fire

plays an important role in stand regeneration. In some areas, a century of fire suppression has led to a buildup of fuels and stand density. In these areas there can be

uncharacteristically intense fires. Some areas that are intensely burned may experience slow regeneration, but others may recover relatively quickly. For example,

the area inside the boundary of the large 1910 fires in Idaho and Montana (Cohen

and Miller 1978; Pyne 2008; Egan 2009) 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 and others 2010).
56 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Assessment of fire effects without a complete cycle of FIA data is not straightforward. During the period covered by this report there were many fires in Idaho.

Some FIA plots within fire boundaries were measured before the fire occurred in

that area, and some were measured after. As a result, within the perimeter of a large

fire there may be pre- and post-fire data, or a plot within the perimeter of a small

fire may represent only pre-fire conditions. This means that normal data compilation methods cannot be used without introducing some element of temporal bias –

that is, plots measured earlier in the inventory will tend to underestimate the effect

of fire because they might have been affected by fire after they were measured.

These limitations on analysis will be reduced as the current inventory cycle is

completed and remeasurement data are acquired during the next cycle. However,

there are some general analyses that can be conducted with the current data. These

results should be considered preliminary.

We used data from the Monitoring Trends in Burn Severity (MTBS) project,

which is an interagency effort being conducted and maintained by the USDA

Forest Service Remote Sensing Applications Center and the US Geological Survey

National Center for Earth Resources Observation and Science (EROS). The purpose of the MTBS project is to consistently map the burn perimeters and severity

of fires across all lands of the United States. The multi-year project was designed

to “assesses the frequency, extent, and magnitude (size and severity) of all large

wildland fires (includes wildfire, wildland fire use, and prescribed fire) in the conterminous United States (CONUS), Alaska, Hawaii, and Puerto Rico for the period

of 1984 through 2010” (Eidenshenk and others 2007). The analysis presented here

is based on burned area perimeters of wildland fires identified by the MTBS program between 2003 and 2009 and FIA plot data for 2004-2009.

MTBS data showed 342 fires and fire complexes (hereafter, fires) burned 4.17

million acres in Idaho between 2003 and 2009. The size of these fires ranged from

about 1000 acres (the minimum size mapped by the MTBS project) to nearly

460,000 acres, with an average of 12,183 acres. Forested plots measured during

the same period occurred within the boundaries 74 of the fires. The remaining 268

fires encompassed only non-forested plots, encompassed plots that have not yet

been measured on the current cycle, or the fires did not encompass an FIA plot location. Two of the largest fires, the Cascade Complex and the East Zone Complex,

encompassed 31 and 32 measured plots, respectively. In contrast, only one measured plot was located within the Murphy Complex, which was the largest fire of

the period at 458,542 acres. The average number of forested plots within a sampled

fire boundary was just under three, and about half of the fires that were sampled by

FIA plots encompassed only one plot.

For large fires, a comparison of the estimate of forested acres to the total number

of acres within the MTBS boundaries gives some indication of the proportion of

forest and non-forest acres within the burned area. For example, the occurrence

of a single forested plot within the Murphy complex indicates that the fire was

largely limited to non-forest. In contrast, the plot-based forest acreage estimates

for the Cascade and the East Zone Complexes are 302,000 and 290,000 acres, very

close to the 317,156 and 318,723 acres included, respectively, within the MTBS

boundaries. This indicates that these two large fires primarily affected forest land.

Although the plot-based and MTBS-based acreage estimates for smaller fires can

be similar, it is not appropriate to draw inference about the mixture of forest and

nonforest for small, individual fires. At this point in the inventory, the scaling factor for a single plot is approximately 10,000 acres, which is larger than most of the
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 57

fires in the MTBS database. As a result, the proportion of burned area in forest vs.

nonforest must be done by aggregating a large number of plots and burned area.

Given that population-scale estimates are difficult to produce with a partial inventory, another way to look at the data is to examine per-acre estimates. There

were 2,482 forested conditions measured in Idaho between 2004 and 2009. Of

these, 2,262 were located outside the MTBS fire boundaries and 220 were located

inside (fig. 33). Of the 220 located inside, 117 were measured prior to the fire in

which they were located and 103 were measured after the fire. Conditions located

outside the burned areas had an average of 119 square feet of basal area per acre in

live and dead trees, with 97 square feet of that in live trees. Conditions within the

burned areas that were measured before the fires occurred averaged 116 square feet

of total basal area per acre and 89 square feet per acre of live trees. While the unburned conditions within the fires appear to have slightly less basal area than conditions outside the burned areas, the ratio of live basal area to total basal area (live

+ dead) was similar for both groups (81% and 77% respectively). This would suggest that the burned areas did not have extraordinarily large amounts of standing

Figure 33: FIA plots measured in Idaho, 

2004-2009, and fire areas from the 

Monitoring Trends in Burn Severity 

(MTBS) program, 2003-2009. Pre-fire 

plots are those that are located within 

a fire perimeter, but were measured 

before the fire occurred. Post-fire 

plots are those that were measured 

at some time after the fire occurred. 

Plots identified as non-forest were 

either classified as non-forest from 

aerial imagery or verified as non-forest with a plot visit. Some forest plots 

can include multiple forest conditions 

or non-forest conditions.
58 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

dead trees prior to the fires, but the lower standing basal area might indicate that

the stands were more open or that there was more down wood in these stands.

When comparing within-fire, pre-burn conditions to within-fire, post-burn conditions, it is possible to estimate the proportion of trees killed within burned areas.

Conditions located within fire boundaries and measured after the fires averaged

104 total square feet of basal area per acre, with only 40 square feet of basal area

remaining in live trees. The lower average total basal area found in within-fire,

post-burn conditions as compared to within-fire, pre-burn conditions (104 vs. 116

sq. ft. per acre) is consistent with the expectation that fire would result in some

basal area being consumed and/or falling down. Likewise, the lower ratio of live

to total basal area (39%) is consistent with the expectation that only partial mortality of trees located within the fire boundaries would occur. If it is assumed that the

pre-burn conditions are representative of the post-burn conditions, then it would

appear that the average fire-caused mortality was about 50 square feet per acre, or

about 55 percent of the pre-fire live basal area.

One of the potential beneficial effects of fire includes the stimulation of aspen regeneration. Although there are only about 708,000 acres of the aspen forest type in Idaho, approximately 1.5 million acres have some aspen component

(see the “Aspen Mortality” section). Of the 191 conditions measured with some

aspen component, only six were located within MTBS fire boundaries and only

one was measured after the fire had burned. Although this sample is very small, it

suggests that the number of potentially fire-disturbed acres with aspen present is

around 51,000 acres, or about 3.3 percent of all acres with an aspen component.

Converting this figure to an annual rate and assuming that fire will be evenly distributed over time and area, it implies that it would take approximately 210 years

for all acres with aspen present to be disturbed by fire. This rate may be lower than

would be necessary to maintain aspen across the Idaho landscape, but it will only

be possible to establish long-term trend with continued monitoring.

The analysis in this section should be considered only a first approximation of

fire effects on Idaho forests. Although the results are generally consistent with expectations, the magnitude of fire-related mortality cannot be stated with precision

at this point in the inventory. However, the data confirm that within fire boundaries

there has been only partial mortality. Additional data and analysis will be required

to determine whether, for example, mortality is more-or-less evenly distributed

among plots within the burned areas or mortality tends to be all-or-none at the plot

scale. Remeasurement data will be necessary to confirm the portions of standing

live and dead trees that are consumed by fire and converted to the down woody

material pool. Also, given the short time period over which the estimate of aspen

stand disturbance has been made, it should be considered with a great deal of caution. However, future measurements will not only enable analysis of fires effects

on aspen, they will also provide important information on the amount and rate of

recovery in all burned areas over time.

Noxious Weeds

Noxious weeds are invasive species of plants that have been identified and targeted by a state for monitoring, control, and eradication. Many of Idaho’s noxious

plant species can have negative effects on forest communities. Noxious species

can displace native flora, alter fire regimes, reduce diversity in the plant and pollinator communities, and generally reduce the diversity and resiliency of forest

ecosystems. FIA field crews record any instance where a noxious weed is found
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 59

on a plot that contains a forested condition. This allows the spatial and temporal

extent of these species to be documented as plots are revisited. A total of 2,541

sample conditions were used to assess the occurrence of noxious plants in Idaho.

These samples represent plots that had a forested condition recorded somewhere

within the boundaries of the four subplots.

Sixteen different species were documented on forested plots in Idaho, with one

or more found on 207 (9%) of the sampled plots (fig. 34). Canada thistle (Cirsium 

arvence), spotted knapweed (Centaurea biebersteinii), and meadow hawkweed

(Hieracium caespitosum) were the most common species by a large margin. These

three species accounted for 73% of the weed occurrences. It appears that Idaho’s

cottonwood and those types found in the hemlock/ sitka spruce forest type group

are most prone to noxious plant infestation. This may be due to one or more factors, including soil conditions, accessibility to livestock grazing, road and foot

traffic, and/or high frequency of both natural and man-induced disturbance. The

cottonwood forest type has the highest percentage of its area infested with at least

one noxious species (fig. 35). However, a low sample size (n = 8) needs to be

considered in this instance. Conversely, one of the most abundant forest types in

Idaho, the subalpine fir type, had a smaller proportion of infested locations (0.4%)

than any other group.

Multiple conditions on a plot often indicate transition zones between forest

types and between forest and non-forest conditions. These “edge” areas are often

dynamic in terms of site occupation, utilization, and species composition. This

makes them more susceptible to occupation by noxious plants than the more stable interior of the stands. Plots in Idaho that had more than one condition (more

than one forest type or a portion of the plot was non-forest) had almost twice the

Figure 34: Number of forested conditions infested by each State-listed noxious plant, Idaho, 2004-2009.
60 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

occurrence of noxious species than did those locations where only a single forested

condition represented the entire plot (12% and 7% respectively). Sixteen percent

of all sampled plots in Idaho had multiple conditions

Special Topic—Bridging the Gap Between Periodic and Annual Forest Inventories: 

Caveats and Limitations

When Idaho’s annual forest inventory began in 2004, a new inventory design

replaced that which was used to produce several periodic inventories that were

summarized in 1990 and 1991 reports, as well as 1997 and 2007 RPA assessments.

The discrepancies between the periodic and annual inventories can be attributed

to inconsistencies in sample design, field methods, and procedures for calculating

statewide forest metrics such as biomass, carbon, and forest land area. The FIA

sample design, plot design, and estimation procedures changed with the implementation of the annual inventory. Attempts to clarify trends between Idaho’s periodic and annual inventories show that comparisons of only plots common to

both inventories yield trends that differ from those produced by direct periodicto-annual comparisons. For example, figure 36 illustrates the effect of comparing

tree volume estimates from each inventory in its entirety versus comparing only

plots that are common to both inventories. The spatial distributions of both annual and periodic plots are displayed in figures 37a-c. Several reasons why direct

comparisons between periodic and annual inventory data may be misleading are

summarized below.

Sample Design: Spatial and Temporal Consistency—The FIA annual inventory

is based on a spatially systematic grid. Ten percent of all plots in the grid are

Figure 35: Percentage of forest area infested with one or more noxious plant species by forest type, Idaho, 

2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 61

sampled each year, and each year’s 10 percent sample is geographically distributed

across the State; therefore, the annual inventory design is considered to be both

spatially and temporally balanced.

In contrast, the various sample designs for the Idaho periodic inventories were

both spatially and temporally inconsistent. Periodic inventories prior to 1992 did

not include National Forest lands, while beginning in 1993 they consisted almost

exclusively of National Forest lands. The pre-1993 inventory relied on a combination of field data and aerial photograph interpretation of plots that were measured during the 1981 Idaho woodland inventory. If no change was observed on

aerial photographs of woodland plots, then the 1981 data were merged with the

data collected during the 1990s field inventory. During the post-1993 inventory,

each National Forest was responsible for conducting its own inventory, and the

inventory methods, sample designs, and the actual inventory year(s) varied among

Forests. For example, large areas of the Payette and Targhee National Forests were

not sampled at all, and thus these areas are under-represented in statewide forest

metrics from this period (figs. 37a,b).

Due to these spatial and temporal inconsistencies in the periodic inventory design, it is likely that forest metrics from the periodic inventory are neither spatially

representative of the entire State or nor temporally representative of a single point

in time. Direct comparisons with the annual inventory estimates are even more

incongruous and should not be made without accounting for these inconsistencies.

Field Methods: Changes in Definitions and Field Procedures—While there are

many minor differences between the methods used during the periodic and annual

Figure 36: Mean volume (cubic feet per acre) represented by each plot in both periodic and annual inventories for live 

and standing dead trees 5.0 inches diameter and greater. The 3rd and 4th bars represent mean volume for plots that 

were surveyed during both periodic and annual inventories. Note that a direct comparison of all periodic plots to all 

annual plots shows a slight decrease in both live and dead volume, while a comparison of only plots in common to 

both inventories shows a steady trend in live volume and an increase in dead volume.
62 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Figure 37: Map showing the fuzzed locations of all periodic plots inventoried prior to 2004, by ownership category, in (a) the periodic inventory, (b) the annual inven- tory, and (c) both inventories.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 63

inventories, there are two major differences that affect how forest land is identified in the field. The first is the definition of “tree,” which in turn defines canopy

cover and thus forest land. The second is the protocol for defining forest land in

heterogeneous areas.

The field manuals for both periodic and annual inventories in Idaho specify

that tree canopy cover of 5 percent or greater qualifies a condition as forest land.

(Although national manuals prescribe a stocking-based definition, the Idaho forest

inventory has consistently used percent canopy cover as a surrogate for stocking.)

The periodic inventory’s definition of a tree was dependent not only on the species

but also on the growth form at the plot. At each plot, woodland trees were classified

as either “tree form” or “shrub form,” based on their height and crown width. For

example, a woodland species such as Rocky Mountain juniper that was found to be

growing horizontally and under a minimum height threshold would be classified as

“shrub form.” In this example, the “shrub form” junipers would not count toward

the definition of forest land, and an entire stand of “shrub form” junipers would

not be considered forest land. In contrast, the annual inventory’s definition of a tree

is solely determined by its inclusion on a list of species, and growth form is not

considered. Under the annual inventory, the stand of “shrub form” junipers in the

example above would be sampled as forest land provided the tree canopy cover

was 5 percent or greater. Therefore, it is possible that plots that were deemed to be

nonforest land during the periodic inventory would now be sampled as forest land.

The periodic and annual inventories also differ in their treatment of areas with

a mixture of forest and nonforest land, which affects their procedures for estimating forest area. During most periodic inventories in Idaho, the land class status at

plot center, i.e., forest or nonforest, determined the single land class that would be

assigned to the entire plot. In contrast, annual inventory procedures allow for multiple land classes on each plot. For example, for plots where the center point was

nonforest but forest land occurs nearby, periodic field procedures stipulated that

the entire plot would be treated as nonforest. Conversely, for plots where the center

point occurred in forest land and portions of the plot were nonforest, the periodic

inventory would treat the entire plot as forest land when producing statewide estimates. In contrast, the annual inventory includes field procedures for delineating

condition classes, which allows both forest and nonforest portions of sample plots

to contribute to statewide forest estimates and, therefore, produces more precise

estimates of forest area.

Procedures for Calculating Statewide Estimates—The procedures for calculating statewide forest metrics have also changed between the periodic and annual

forest inventories. One of these changes pertains to the statistical methods used to

estimate forest land area in specific ownership categories, and another is related to

how those ownership categories are determined for each plot.

Although FIA attempts to obtain data from every plot in the sample grid, not every plot is actually sampled. Nonsampled plots are defined as those that cannot be

sampled by a field crew, either because access to the plot location is denied by land

owners or managers, or because the plot is deemed too hazardous to safely survey

due to terrain or other environmental factors. Between 2004 and 2009, about 15

percent of all potentially forested private land plots were not sampled due to denial

of access by private landowners. Less than 3 percent of all field plots, among all

owner classes, were nonsampled for other reasons (i.e., hazardous, denial of access

on non-private lands, etc.). Therefore, nonsampled plots occurred at a higher rate

on private lands than on any other ownership category.
64 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

The inability to sample every plot affects statewide estimates of forest land

area, and the periodic and annual inventories use different statistical methods to

account for nonsampled plots. The periodic inventory relied on area control procedures, wherein the relative contribution of each sampled plot was weighted with

respect to the total number of acres in each ownership group across the entire State.

Nonsampled plots were not included in estimates of forest area, and the weights

assigned to sampled plots were adjusted accordingly. Under the annual inventory,

the statistical methods for estimating forest area assume that all plots have an equal

chance of being nonsampled (Patterson and others 2012). However, we know this

assumption is not true because nearly all denied-access plots occur on private

lands. In an investigation of the effect that nonsampled plots can have on estimates

of forest land area, Patterson and others (2012) found that a failure to account for

the fact that certain subpopulations have different proportions of nonsampled plots

(e.g., private versus public forest lands) can lead to considerable under-estimation

of forest area in the subpopulations where a relatively high proportion of plots are

nonsampled. They recommended that FIA estimation procedures be revised to account for different rates of nonsampled plots among subpopulations. FIA’s current

statistical estimation procedures may be underestimating the area of private forest

land in Idaho due to the underlying assumptions about nonsampled plots.

Changes in the methods for determining plot ownership have also confounded

trends in forest land area, as reported by ownership class. During the periodic

inventory, the ownership status of each plot was assigned using 1:100,000 BLM

surface management maps. The annual inventory procedure combines the most

current GIS layers and county plat maps to verify the ownership class assigned to

each plot, and several errors in previous plot ownership attributes have been discovered and corrected using this procedure. In general, previous errors in ownership class assignments were biased against private forest lands.

Implications for Interpreting Long-Term Trends in Volume, Biomass, Carbon, 

and Forest Land Area—As mentioned above, the periodic inventory metrics alone

are likely not representative of the State of Idaho as a whole, yet data from the

early 1990s is often used as a baseline and annual inventory data are compared to

this baseline. Figure 36 illustrates the possibility that erroneous conclusions may

be drawn by making such comparisons. The first two bars show mean volume per

acre based on the entire periodic and the entire annual inventory, respectively, and

it appears that the total volume and live volume both decreased substantially. The

third and fourth bars show volume based only on plots that were sampled during

both inventories, for periodic and annual inventories, respectively. Based on this

apples-to-apples comparison, live volume has only slightly decreased and total

volume has increased. Therefore, directly comparing periodic versus annual inventory data produces trends that are either more substantial or in opposition to those

observed by comparing only remeasured plots.

Despite these caveats, scientists and policy-makers often rely on forest inventory data to quantify long-term trends in metrics such as volume, standing forest biomass, forest carbon, and forest land area. In their analysis of forest carbon

for the U.S. greenhouse gas inventory, Heath and others (2011) specifically mentioned that observed changes in Idaho’s forest carbon since 1990 were likely due

to changes in forest inventory methods. Any future analyses of long-term trends in

forest metrics that utilize Idaho’s periodic forest inventory data should not consist

of direct comparisons of summary statistics, but rather must account for the many

differences in inventory methods described here.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 65

Conclusions

Idaho’s forests include a variety of tree and understory species, age-classes,

and disturbance dynamics that together create a multitude of complex ecosystems.

These forests provide an abundance of services, including timber products, recreational opportunities, air and water quality, wildlife habitat, and scenic beauty.

The tree species of Idaho are adapted to a wide range of soils, moisture, and topography, from low-elevation juniper woodlands, to wildlife-rich aspen stands

in moisture-trapping snow pockets, to the massive fir and hemlock forests of the

northern mountains.

Most of the forests in Idaho are administered by Federal agencies, primarily

the Forest Service and the Bureau of Land Management. These forests are to be

managed to meet the multiple-use objectives defined in statutes and to provide a

sustained flow of outputs that meet the expectations of an ever-growing public as

well as industries that support Idaho’s rural economies.

As the number of people living in and using Idaho’s forests increases, so does

the challenge of providing a variety of quality experiences and products derived

from the forest. Furthermore, the dynamic nature of Idaho’s forest ecosystems dictates ever-changing conditions and management strategies. Extensive wildfires,

mountain pine beetle infestations, aspen decline, whitebark pine mortality, and

noxious weeds are a few of the factors addressed in this report that currently affect

Idaho’s forests. The issues of the future might be different and it is important to

have the tools to identify potential issues as soon as possible. In addition, the application of data for down woody material, understory vegetation, standing dead

trees, damage indicators, and others have only been briefly addressed in this report.

Many of the analyses performed for this report demonstrate both the utility of FIA

data as an analysis tool and the potential for further, more in-depth analysis of a

wide range of topics. Data from FIA’s annualized inventory will continue to provide valuable information to resource managers and researchers who are interested

in the quantity and condition of resources provided by Idaho’s forests.

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 net annual 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 (BA)—The cross-sectional area of a tree stem/bole (trunk) at the point

where diameter is measured, inclusive of bark. BA 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 above-ground portions of trees:

bole/stem (trunk), bark, and branches. Biomass estimates can be computed for live

and/or dead trees.
66 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Board-foot volume—A board-foot is a unit of measure indicating the amount of wood

contained in an unfinished board 1-foot wide, 1-foot long, and 1-inch thick. Boardfoot 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 attributers that

identify, define, and stratify the area associated with a plot. Examples of such

attributes include condition status, forest type, stand origin, stand size, owner

group, and stand 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. Maximum crown cover for a site is 100 percent; overlapping cover is not

double counted.

Cubic-foot volume (merchantable)—A cubic-foot is 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 above ground), 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 multistemmed 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.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 67

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 (LC) 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—Acircularsample 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.

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 one 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 one acre in size. Grazed woodlands, reverting fields, and pastures that are

not actively maintained are included if 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.

to the central stem.

Hardwoods—Dicotyledonous trees, usually broadleaf and deciduous.

Hexagonal grid (Hex)—A hexagonal grid formed from 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 ha) and contains one inventory plot. The base

grid can be subdivided into smaller hexagons to intensify the sample.
68 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

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.

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, and so forth. 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.

• 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.

Merchantable portion—For trees measured at d.b.h. and 5.0-inches 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.

Miscellaneous 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.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 69

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.

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 lands—Public lands administered by the Park Service, U.S.

Department of the Interior, such as National Parks, National Monuments, 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.

Unreserved forest land—Forest land not withdrawn from management for production of wood products through statute or administrative designation.

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.

Other wooded land—Land that has 5 to 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 one 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 wide or one acre in size. Grazed woodlands, reverting fields, and pastures that

are not actively maintained are included if above qualifications are satisfied.

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.

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 A) on forest

land classified as a timber forest type (see Appendix B).
70 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

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 MAI). Productivity values for forest land provide an 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. Productivity is sometimes referred to as “Yield” or “Mean annual

increment (MAI).”

Removals—The net volume of sound (growing-stock) trees removed from the inventory by harvesting or other cultural operations(such astimber-stand improvement),

by land clearing, or by changes in land use (such as a shift to wilderness).

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 saw-log portion ofsawtimbersize trees in board feet.

Seedlings—Live trees less than 1.0 inch d.b.h./d.r.c.

Site index—A measure of forest 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.

Stand density index (SDI)—A widely used measure developed by Reineke (1933),

and is an index 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
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 71

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 tree—To qualify as a standing dead tally tree, dead trees must be at least

5.0 inches in diameter, have a bole that has an unbroken actual length of at least 4.5

feet, and lean 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 separated greater than 50

percent (either above or below 4.5 feet), 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; do not consider cut and

removed volume. 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 percentstocking, but hasthe potential to again become 10 percentstocked.

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.

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 A) on forest

land designated as a timber forest type (see Appendix B)..
72 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

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 A)

on forest land designated as a timber forest type and all forest lands designated as

a woodland forest type (see Appendix B).

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, fenceposts, and

Christmas trees. These species include pinyon, juniper (except Western 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.

Note: For the FIA national glossary please go to:

http://socrates.lv-hrc.nevada.edu/fia/ab/issues/pending/glossary.html.

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Appendix A: Species Group, Common Name, Scientific Name, and 

Timber (T) or Woodland (W) Designation for Trees Measured in Idaho’s Annual Inventory.

Cottonwood and aspen

Black cottonwood (Populus balsamifera ssp. trichocarpa) T

Narrowleaf cottonwood (Populus angustifolia) T

Quaking aspen (Populus tremuloides) T

Douglas-fir

Douglas-fir (Pseudotsuga menziesii) T

Engelmann and other spruces

Engelmann spruce (Picea engelmannii) T

Lodgepole pine

Lodgepole pine (Pinus contorta) T

Other western hardwoods

Paper birch (Betula papyrifera) T

Water birch (Betula occidentalis) T

Other western softwoods

Limber pine (Pinus flexilis) T

Mountain hemlock (Tsuga mertensiana) T

Pacific yew (Taxus brevifolia) T

Subalpine larch (Larix lyallii) T

Whitebark pine (Pinus albicaulis) T

Ponderosa and Jeffrey pines

Ponderosa pine (Pinus ponderosa) T

Red alder

Red alder (Alnus rubra) T

True fir

Grand fir (Abies grandis) T

Subalpine fir (Abies lasiocarpa) T

Western hemlock

Western hemlock (Tsuga heterophylla) T

Western larch

Western larch (Larix occidentalis) T

Western redcedar

Western redcedar (Thuja plicata) T

Western white pine

Western white pine (Pinus monticola) T

Western woodland hardwoods

Bigtooth maple (Acer grandidentatum) W

Curlleaf mountain-mahogany (Cercocarpus ledifolius) W

Western woodland softwoods

Rocky Mountain juniper (Juniperus scopulorum) W

Singleleaf pinyon (Pinus monophylla) W

Western juniper (Juniperus occidentalis) W

Utah juniper (Juniperus osteosperma) W
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 77

Appendix B: Forest Type Groups, Forest Type Names, and Timber (T) 

or Woodland (W) Designation for Forest Type.

Alder-maple group

Red alder T

Aspen-birch group

Aspen T

Paper birch T

Douglas-fir group

Douglas-fir T

Elm-ash-cottonwood group

Cottonwood T

Fir-spruce-mountain hemlock group

Engelmann spruce T

Engelmann spruce-subalpine fir T

Grand fir T

Mountain hemlock T

Subalpine fir T

Hemlock-Sitka spruce group

Western hemlock T

Western redcedar T

Lodgepole pine group

Lodgepole pine T

Nonstocked

Nonstocked (only as stand-size class) T or W

Other hardwoods group

Other hardwoods W

Other western softwoods group

Limber pine T

Whitebark pine T

Western juniper W

Pinyon-juniper group

Juniper woodland W

Pinyon-juniper woodland W

Rocky Mountain juniper W

Ponderosa pine group

Ponderosa pine T

Western white pine group

Western white pine T

Western larch group

Western larch T

Woodland hardwoods group

Cercocarpus (mountain brush) woodland W

Intermountain maple woodland W
78 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Appendix C: Volume, Biomass, and Site Index Equation Sources.

Volume

Chojnacky (1985) was used for curlleaf mountain-mahogany volume

estimation.

Chojnacky (1994) was used for Rocky Mountain juniper and Utah juniper

volume estimation.

Kemp (1956) was used for black cottonwood, Engelmann spruce, mountain

hemlock, narrowleaf cottonwood, paper birch, plains cottonwood, quaking aspen, red alder, subalpine fir, water birch, western hemlock, and

western redcedar volume estimation.

Volume equations provided by the USDA Forest Service’s Northern

Research Station were used for American elm, boxelder, and green ash

volume estimation. [Documentation on file at Rocky Mountain Research

Station, Ogden, UT.]

Biomass

Chojnacky (1984) was used for curlleaf mountain mahogany biomass

estimation.

Chojnacky and Moisen (1993) was used for 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 Douglas-fir, Engelmann spruce, limber pine,

lodgepole pine, Pacific yew, ponderosa pine, and subalpine fir, subalpine

larch, western larch, western white pine, and whitebark pine site index

estimation.

Edminster and others (1985) was used for American elm, black cottonwood,

boxelder, green ash, narrowleaf cottonwood, paper birch, plains cottonwood, quaking aspen, red alder, and water birch site index estimation.

Stage (1966, 1969) was used for grand fir site index estimation. [Original

equations were reformulated by J. Shaw; documentation on file at Rocky

Mountain Research Station, Ogden, UT.]

Equations from RMSTAND (USDA 1993) were used for mountain hemlock, western hemlock, and western redcedar site index estimation.

Stage (1966, 1969) 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.]
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 79

Appendix D: Standard Reporting Tables.

Table 1: Percentage of area by land status.

Table 2: Area of accessible forest land by owner class and forest land status.

Table 3: Area of accessible forest land by forest type group and productivity class.

Table 4: Area of accessible forest land by forest type group, ownership group, and land status.

Table 5: Area of accessible forest land by forest type group and stand-size class.

Table 6: Area of accessible forest land by forest type group and stand-age class.

Table 7: Area of accessible forest land by forest type group and stand origin.

Table 8: Area of forest land by forest type group and primary disturbance class.

Table 9: Area of timberland by forest type group and stand-size class.

Table 10: Number of live trees on forest land by species group and diameter class.

Table 11: Number of growing stock trees on timberland by species group and diameter class.

Table 12: Net volume of all live trees by owner class and forest land status.

Table 13: Net volume of all live trees on forest land by forest type group and stand-size class.

Table 14: Net volume of all live trees on forest land by species group and ownership group.

Table 15: Net volume of all live trees on forest land by species group and diameter class.

Table 16: Net volume of all live trees on forest land by forest type group and stand origin.

Table 17: Net volume of growing stock trees on timberland by species group and diameter class.

Table 18: Net volume of growing stock trees on timberland by species group and ownership group.

Table 19: Net volume of sawtimber trees (International 1/4 inch rule) on timberland by species group and

diameter class.

Table 20: Net volume of sawtimber trees on timberland by species group and ownership group.

Table 21: Average annual net growth of all live trees by owner class and forest land status.

Table 22: Average annual net growth of all live trees on forest land by forest type group and stand-size class.

Table 23: Average annual net growth of all live trees on forest land by species group and ownership group.

Table 24: Average annual net growth of growing stock trees on timberland by species group and ownership group.

Table 25: Average annual mortality of all live trees by owner class and forest land status.

Table 26: Average annual mortality of all live trees on forest land by forest type group and stand-size class.

Table 27: Average annual mortality of all live trees on forest land by species group and ownership group.

Table 28: Average annual mortality of growing stock trees on timberland by species group and ownership group.

Table 29a: Aboveground dry weight (regional equation method) of all live trees by owner class and forest land

status.

Table 29b: Aboveground dry weight (component ratio method) of all live trees by owner class and forest land

status.

Table 30a: Aboveground dry weight (regional equation method) of all live trees on forest land by species group

and diameter class.

Table 30b: Aboveground dry weight (component ratio method) of all live trees on forest land by species group and

diameter class.

Table 31: Area of accessible forest land by Forest Survey Unit, county and forest land status.

Table 32: Area of accessible forest land by Forest Survey Unit, county, ownership group and forest land status.

Table 33: Area of timberland by Forest Survey Unit, county and stand-size class.

Table 34: Area of timberland by Forest Survey Unit, county and stocking class.

Table 35: Net volume of growing stock and sawtimber (International 1/4 inch rule) on timberland by Forest

Survey Unit, county, and major species group.

Table 36: Average annual net growth of growing stock and sawtimber (International 1/4 inch rule) on timberland

by Forest Survey Unit, county, and major species group.

Table 37: Sampling errors by Forest Survey Unit and county for area of timberland, volume, average annual net

growth, average annual removals, and average annual mortality on timberland.
80 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Accessible forest land

Unreserved forest land

Unproductive

Reserved forest land

Nonforest and other land

Water

Nonsampled land

 

Total area (thousands of acres)

Timberland 29.9

 2.2

Total unreserved forest land 32.1

Productive 6.2

Total reserved forest land 6.3

Nonforest land 58.0

Non-Census 0.1

Access denied 1.2

All land

 53,485

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.

Land status Percentage of area

100.0

Other 0.2

Hazardous conditions 1.0

All nonforest and other land 59.1

Census 1.1

All accessible forest land 38.4

Unproductive 0.2

Table 1—Percentage of area by land status, Idaho, cycle 2, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 81 Forest Service Other Federal State and local government Private National forest National Park Service Bureau of Land Management Department of Defense or Energy State Undifferentiated private 12,226.7 - - 613.8 21.5 1,183.2 2,571.6 Table 2--Area of accessible forest land by owner class and forest land status, Idaho, cycle 2, 2004-2009. 539.9 - - 330.3 10.1 85.0 239.2 12,766.6 - - 944.1 31.7 1,268.2 2,810.8 3,388.2 61.6 - - - - 31.4 - - (Table 2 continued on next page) 16,616.8 1,204.5 17,821.3 3,481.1 All owners 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. 68.1 19.1 - - - - - - - - 3,456.3 80.6 - - - - 31.4 - - 16,222.9 80.6 944.1 31.7 1,299.5 2,810.8 87.2 3,568.3 21,389.6 Owner class Timberland Unproductive Total Productive Unreserved forests Reserved forests Unproductive Total All forest land Table 2—Area of accessible forest land by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In thousand acres)
82 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 306.5 35.2 - - - - 10.6 110.5 - - - - 249.3 - - 126.1 - - 2.8 279.0 171.7 Table 3--Area of accessible forest land by forest type group and productivity class, Idaho, cycle 2, 2004-2009. - - 2,023.3 284.0 10.8 1,608.1 1,528.1 9.9 1.9 400.0 10.0 492.1 6.8 - - - - 904.8 - - 2,207.6 807.6 - - 2,187.1 677.8 252.2 144.5 6.6 23.2 159.1 - - - - - - 391.5 - - 1,368.8 393.3 14.8 1,387.2 124.5 397.2 100.4 - - 39.9 17.2 - - - - - - 161.7 (Table 4 continued on next page) 1,291.7 7,279.7 6,857.2 4,004.9 All forest-type groups 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. - - 569.3 105.2 19.7 722.0 14.9 217.7 32.5 - - - - - - - - - - - - 55.8 - - 84.3 - - 9.8 100.9 - - 10.6 - - - - - - - - - - - - - - 13.3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,737.0 219.0 - - 306.5 6,288.5 1,590.2 55.1 6,015.9 2,455.8 887.5 279.3 655.9 73.0 794.5 6.8 2.8 279.0 1,698.9 21,389.6 0-19 20-49 50-84 85-119 Site-productivity class (cubic feet/acre/year) Forest-type group 120-164 165-224 All classes 225+ Table 3—Area of accessible forest land by forest type group and productivity class, Idaho, cycle 2, 2004-2009. (In thousand acres). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 306.5 35.2 - - - - 10.6 110.5 - - - - 249.3 - - 126.1 - - 2.8 279.0 171.7 Table 3--Area of accessible forest land by forest type group and productivity class, Idaho, cycle 2, 2004-2009. - - 2,023.3 284.0 10.8 1,608.1 1,528.1 9.9 1.9 400.0 10.0 492.1 6.8 - - - - 904.8 - - 2,207.6 807.6 - - 2,187.1 677.8 252.2 144.5 6.6 23.2 159.1 - - - - - - 391.5 - - 1,368.8 393.3 14.8 1,387.2 124.5 397.2 100.4 - - 39.9 17.2 - - - - - - 161.7 (Table 4 continued on next p

 1,291.7 7,279.7 6,857.2 4,004.9 All forest-type groups 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. - - 569.3 105.2 19.7 722.0 14.9 217.7 32.5 - - - - - - - - - - - - 55.8 - - 84.3 - - 9.8 100.9 - - 10.6 - - - - - - - - - - - - - - 13.3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,737.0 219.0 - - 3

 6,2 1,5

 

 6,0 2,4

 8 2 6

 

 7 2

 1,6

 21,3

0-19 20-49 50-84 85-119 Site-productivity class (cubic feet/acre/year) Forest-type group 120-164 165-224 

clas

225+
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 83 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock group Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked - - 3,964.5 893.1 35.4 3,909.7 1,552.4 430.3 139.7 211.5 - - 407.6 - - - - - - 682.4 Table 4--Area of accessible forest land by forest type group, ownership group, and land status, Idaho, cycle 2, 2004-2009. 67.2 990.4 200.6 - - 957.1 704.0 21.2 - - 175.4 - - 84.5 - - - - 147.0 648.9 - - 260.7 30.4 - - 88.1 - - 19.6 - - 64.7 10.4 62.5 - - - - - - 99.0 120.8 10.0 - - - - 10.3 61.6 - - - - 100.3 - - 12.2 - - - - 74.0 31.8 (Table 4 continued on next page) 12,226.7 3,996.3 635.3 421.0 All forest-type groups 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. - - 299.7 126.9 - - 406.8 38.5 99.8 57.9 44.7 2.5 35.8 - - - - - - 70.6 - - - - - - 9.8 21.5 - - - - - - 37.1 - - 18.0 - - - - 20.1 9.9 1,183.2 116.3 2,571.6 21,389.6 239.2 - - 763.1 339.2 9.9 622.3 92.5 316.6 81.7 - - 60.1 139.3 6.8 - - - - 140.2 118.5 - - - - - - - - 6.8 - - - - 22.3 - - 34.7 - - 2.8 37.9 16.1 Forest-type group Timber- land Other forest land Timber- land Other forest land Forest Service Timber- land Other forest land Timber- land Other forest land All forest land Other Federal State and local government Undifferentiated private 306.5 6,288.5 1,590.2 55.1 6,015.9 2,455.8 887.5 279.3 655.9 73.0 794.5 6.8 2.8 279.0 1,698.9 Table 4—Area of accessible forest land by forest type group, ownership group, and land status, Idaho, cycle 2, 2004-2009. (In thousand acres)
84 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 283.2 5,191.0 1,407.3 33.7 4,291.3 1,044.8 710.7 167.4 486.3 73.0 117.9 - - - - 126.6 - - Table 5--Area of accessible forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 20.5 401.4 27.3 10.6 543.8 789.6 78.7 59.7 35.2 - - 283.9 - - - - 55.4 - - 2.8 696.1 155.6 10.8 1,180.8 621.5 98.1 52.1 134.4 - - 392.7 6.8 2.8 97.0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 5 continued on next page) 13,933.0 2,306.1 3,451.6 - - All forest-type groups 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. - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,698.9 1,698.9 306.5 6,288.5 1,590.2 55.1 6,015.9 2,455.8 887.5 279.3 655.9 73.0 794.5 6.8 2.8 279.0 1,698.9 21,389.6 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest-type group Nonstocked All size classes Table 5—Area of accessible forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. (In thousand acres). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 306.5 35.2 - - - - 10.6 110.5 - - - - 249.3 - - 126.1 - - 2.8 279.0 171.7 Table 3--Area of accessible forest land by forest type group and productivity class, Idaho, cycle 2, 2004-2009. - - 2,023.3 284.0 10.8 1,608.1 1,528.1 9.9 1.9 400.0 10.0 492.1 6.8 - - - - 904.8 - - 2,207.6 807.6 - - 2,187.1 677.8 252.2 144.5 6.6 23.2 159.1 - - - - - - 391.5 - - 1,368.8 393.3 14.8 1,387.2 124.5 397.2 100.4 - - 39.9 17.2 - - - - - - 161.7 (Table 4 continued o

 1,291.7 7,279.7 6,857.2 4,004.9 All forest-type groups 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. - - 569.3 105.2 19.7 722.0 14.9 217.7 32.5 - - - - - - - - - - - - 55.8 - - 84.3 - - 9.8 100.9 - - 10.6 - - - - - - - - - - - - - - 13.3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,737.0 219.0 - - 

0-19 20-49 50-84 85-119 Site-productivity class (cubic feet/acre/year) Forest-type group 120-164 165-224 

225+
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 85 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock group Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,698.9 Table 6--Area of accessible forest land by forest type group and stand-age class, Idaho, cycle 2, 2004-2009. - - 555.7 148.2 10.8 840.9 536.4 78.1 52.1 67.6 - - 307.9 6.8 2.8 36.4 - - 2.8 188.8 24.4 9.9 365.2 105.1 22.6 - - 57.2 - - 80.3 - - - - 55.6 - - 52.1 456.1 240.4 10.6 270.1 176.3 68.5 33.4 9.9 - - 113.4 - - - - 20.8 - - (Table 6 continued on next page) 1,698.9 2,643.7 911.9 1,451.5 All forest-type groups 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. 56.0 1,096.0 380.4 9.8 734.7 448.9 191.5 114.0 19.8 40.5 201.0 - - - - 20.4 - - 66.2 1,389.0 315.3 - - 1,038.6 569.2 193.9 29.8 67.3 22.8 78.4 - - - - 46.2 - - 50.2 1,103.1 184.8 4.2 876.2 263.6 112.3 33.9 49.7 9.7 13.5 - - - - 24.6 - - 3,312.9 3,816.9 2,725.8 306.5 6,288.5 1,590.2 55.1 6,015.9 2,455.8 887.5 279.3 655.9 73.0 794.5 6.8 2.8 279.0 1,698.9 21,389.6 17.8 507.9 111.4 - - 792.1 183.7 116.9 10.8 51.5 - - - - - - - - 51.9 - - 20.5 343.2 71.3 9.8 450.7 114.7 34.9 5.3 57.7 - - - - - - - - 5.2 - - 7.6 214.9 20.5 - - 262.9 36.8 26.3 - - 75.8 - - - - - - - - 7.9 - - 20.3 149.7 39.2 - - 181.4 21.0 21.9 - - 64.6 - - - - - - - - - - - - 12.7 284.1 54.1 - - 203.2 - - 20.6 - - 134.8 - - - - - - - - 10.2 - - 1,844.0 1,113.4 652.7 498.1 719.7 Non stocked 1-20 21-40 41-60 Stand-age class (years) Forest-type group 61-80 81-100 All classes 101-120 121-140 141-160 161-180 181-200 201+ Table 6—Area of accessible forest land by forest type group and stand-age class, Idaho, cycle 2, 2004-2009. (In thousand acres).
86 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Pinyon / juniper group

Douglas-fir group

Ponderosa pine group

Western white pine group

Fir / spruce / mountain hemlock grou

Lodgepole pine group

Hemlock / Sitka spruce group

Western larch group

Other western softwoods group

Elm / ash / cottonwood group

Aspen / birch group

Alder / maple group

Other hardwoods group

Woodland hardwoods group

Nonstocked

 306.5

 6,237.3

 1,482.0

 55.1

 5,995.4

 2,436.6

 887.5

 268.2

 655.9

 73.0

 784.2

 6.8

 2.8

 279.0

 1,689.5

T

 - -

 51.2

 108.2

 - -

 20.5

 19.2

 - -

 11.1

 - -

 - -

 10.3

 - -

 - -

 - -

 9.4

(Table 7 continued on next page)

All forest-type groups 21,159.8 229.8

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.

 306.5

 6,288.5

 1,590.2

 55.1

 6,015.9

 2,455.8

 887.5

 279.3

 655.9

 73.0

 794.5

 6.8

 2.8

 279.0

 1,698.9

 21,389.6

Natural

stands

Artificial

 regeneration

Stand origin

 Forest-type group

All forest

land

Table 7—Area of accessible forest land by forest type group and stand origin, Idaho, cycle 2, 2004-2009.

(In thousand acres).

Pinyon / juniper group

Douglas-fir group

Ponderosa pine group

Western white pine group

Fir / spruce / mountain hemlock grou

Lodgepole pine group

Hemlock / Sitka spruce group

Western larch group

Other western softwoods group

Elm / ash / cottonwood group

Aspen / birch group

Alder / maple group

Other hardwoods group

Woodland hardwoods group

Nonstocked

 306.5

 35.2

 - -

 - -

 10.6

 110.5

 - -

 - -

 249.3

 - -

 126.1

 - -

 2.8

 279.0

 171.7

Table 3--Area of accessible forest land by forest type group and productivity class, Idaho

 - -

 2,023.3

 284.0

 10.8

 1,608.1

 1,528.1

 9.9

 1.9

 400.0

 10.0

 492.1

 6.8

 - -

 - -

 904.8

 - -

 2,207.6

 807.6

 - -

 2,187.1

 677.8

 252.2

 144.5

 6.6

 23.2

 159.1

 - -

 - -

 - -

 391.5

 - -

 1,368.8

 393.3

 14.8

 1,387.2

 124.5

 397.2

 100.4

 - -

 39.9

 17.2

 - -

 - -

 - -

 161.7

All forest-type groups 1,291.7 7,279.7 6,857.2 4,004.9

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.

0-19 20-49 50-84 85-119

Site-productivity class (cubic feet/

 Forest-type group 
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 87 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock group Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 278.9 5,419.6 1,368.7 55.1 5,400.2 1,997.4 837.4 268.9 527.3 70.5 724.0 6.8 2.8 271.7 1,010.2 Table 8--Area of forest land by forest type group and primary disturbance class, Idaho, cycle 2, 2004-2009. - - 252.2 19.3 - - 246.6 172.0 - - - - 57.3 - - - - - - - - - - 42.0 - - 232.0 29.7 - - 124.9 57.1 28.7 - - - - - - 17.5 - - - - - - 10.7 - - - - - - - - 11.3 - - 10.6 - - 21.0 - - - - - - - - - - - - (Table 8 continued on next page) 18,239.5 789.5 500.5 42.9 All forest-type groups 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. 7.3 237.7 149.8 - - 134.8 175.4 - - 10.4 15.6 - - 33.9 - - - - - - 590.0 20.3 115.2 14.1 - - 38.4 53.8 - - - - 29.8 2.5 9.2 - - - - 7.3 43.1 - - 5.0 - - - - - - - - - - - - - - - - - - - - - - - - - - 1,355.0 333.8 5.0 306.5 6,288.5 1,590.2 55.1 6,015.9 2,455.8 887.5 279.3 655.9 73.0 794.5 6.8 2.8 279.0 1,698.9 21,389.6 - - - - 8.6 - - 10.8 - - - - - - - - - - - - - - - - - - - - 19.4 - - 19.7 - - - - 15.1 - - - - - - - - - - - - - - - - - - - - 34.7 Forest-type group All forest land None Insects Disease WeatherDisturbance class Fire Domestic animals Wild animals Human Other Table 8—Area of forest land by forest type group primary disturbance class, Idaho, cycle 2, 2004-2009. (In thousand acres)
88 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Nonstocked 4,448.4 1,209.3 23.9 3,605.8 764.3 689.5 167.4 267.6 73.0 117.9 - - - - Table 9--Area of timberland by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 315.8 27.3 10.6 466.9 585.9 78.7 59.7 10.0 - - 223.6 - - - - 523.7 153.0 10.8 954.3 333.2 98.1 52.1 43.2 - - 303.6 6.8 - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 5 continued on next page) 11,367.1 1,778.6 2,479.0 - - All forest-type groups 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. - - - - - - - - - - - - - - - - - - - - - - 992.2 992.2 5,288.0 1,389.6 45.3 5,027.0 1,683.4 866.3 279.3 320.8 73.0 645.1 6.8 992.2 16,616.8 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest-type group Nonstocked All size classes Table 9—Area of timberland by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. (In thousand acres). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Other hardwoods group Woodland hardwoods group Nonstocked 306.5 35.2 - - - - 10.6 110.5 - - - - 249.3 - - 126.1 - - 2.8 279.0 171.7 Table 3--Area of accessible forest land by forest type group and productivity class, Idaho, cycle 2, 2004-2009. - - 2,023.3 284.0 10.8 1,608.1 1,528.1 9.9 1.9 400.0 10.0 492.1 6.8 - - - - 904.8 - - 2,207.6 807.6 - - 2,187.1 677.8 252.2 144.5 6.6 23.2 159.1 - - - - - - 391.5 - - 1,368.8 393.3 14.8 1,387.2 124.5 397.2 100.4 - - 39.9 17.2 - - - - - - 161.7 (Table 4 continued on 

 1,291.7 7,279.7 6,857.2 4,004.9 All forest-type groups 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. - - 569.3 105.2 19.7 722.0 14.9 217.7 32.5 - - - - - - - - - - - - 55.8 - - 84.3 - - 9.8 100.9 - - 10.6 - - - - - - - - - - - - - - 13.3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,737.0 219.0 - - 

0-19 20-49 50-84 85-119 Site-productivity class (cubic feet/acre/year) Forest-type group 120-164 165-224 

225+
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 89 Western softwood species groups Western hardwood species groups Table 10--Number of live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (Table 10 continued on next page) 861,192 606,814 406,699 269,686 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. 176,698 7,777,079 Softwood species groups Hardwood species groups 807,349 53,843 569,849 36,964 388,359 18,340 259,295 10,391 172,757 3,940 7,120,312 656,767 All softwoods All hardwoods 118,982 1,581 77,714 926 51,405 603 61,398 508 27,172 304 11,603 122 6,702 - - 4,503 - - 120,563 78,640 52,009 61,906 27,476 11,725 6,702 4,503 1,347,593 117,210 1,464,803 3,215,629 412,036 3,627,665 Species group Diameter class (inches) 37.0+ All classes 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- 18.9 19.0- 20.9 21.0- 24.9 25.0- 28.9 29.0- 32.9 33.0- 36.9 28,021 4,928 18,985 1,041 545 6,931 1,718 3,290 5,303 1,900 5,054 620 64 242 21,981 4,667 11,629 430 302 4,441 1,100 1,373 2,179 1,001 2,304 299 65 239 24,087 6,372 12,756 1,278 605 6,777 1,378 680 3,498 697 3,269 311 197 10,847 4,018 4,971 245 190 2,745 553 2,082 620 901 304 3,705 1,894 2,390 241 59 849 380 1,458 261 365 122 2,779 635 1,356 122 816 124 627 122 122 864 435 1,075 249 1,760 121 1,307,268 187,867 2,685,182 257,046 71,486 310,300 71,821 1,263,170 436,549 68,603 461,019 336,638 8,939 35,188 276,002 462,333 58,548 1,433,498 141,595 38,990 120,644 17,075 463,326 233,820 19,502 226,299 216,317 6,720 12,830 176,168 213,425 29,618 514,848 50,113 17,671 57,155 7,459 269,995 80,495 10,117 96,696 54,603 739 4,670 57,198 143,142 21,597 265,531 24,689 5,673 32,672 10,369 206,961 42,518 9,883 44,316 23,726 648 9,995 19,473 97,979 13,531 107,889 9,148 1,465 17,191 8,260 89,211 16,262 6,580 20,843 10,571 59 2,113 5,597 111,957 15,567 168,671 16,585 3,285 24,731 9,378 154,539 23,900 7,978 33,258 20,258 254 3,941 12,512 80,244 10,315 68,173 5,524 1,172 15,194 5,899 44,768 10,577 4,073 13,356 6,331 194 1,202 2,664 61,181 8,273 43,911 3,843 860 11,863 4,572 20,337 6,310 3,230 8,376 2,188 194 246 1,312 44,723 7,470 29,498 2,194 667 8,043 3,556 8,689 5,760 2,641 5,741 989 65 127 400 Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Western woodland hardwoods - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Table 10—Number of live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (In thousand trees).
90 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods 117,970 19,434 219,000 24,263 5,609 25,710 10,304 149,525 41,307 29,091 15,922 648 9,562 Table 11--Number of growing-stock trees on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. 90,330 13,934 137,756 16,520 3,226 19,988 9,378 118,784 23,403 22,315 15,347 254 3,941 82,452 12,458 89,904 9,083 1,465 13,349 8,196 64,951 16,134 14,571 9,085 59 2,113 66,892 9,492 57,768 5,524 1,172 11,794 5,899 34,209 10,513 9,238 5,422 194 1,202 (Table 11 continued on next page) 668,345 475,176 323,823 219,320 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. 52,619 7,270 37,547 3,778 860 8,832 4,572 16,153 6,119 6,094 1,883 194 246 527,886 88,360 613,466 64,654 14,524 102,844 47,159 394,485 118,680 94,255 49,945 1,480 17,255 146,168 2,134,992 Softwood species groups Hardwood species groups 642,213 26,132 455,635 19,541 312,565 11,257 212,502 6,818 143,844 2,324 2,066,312 68,679 All softwoods All hardwoods 39,274 6,769 26,020 2,129 667 5,464 3,556 6,531 5,444 4,058 873 65 127 24,128 4,292 16,762 1,041 545 5,489 1,718 2,716 5,175 3,845 378 64 18,662 3,710 9,845 430 302 3,245 1,100 1,060 2,051 1,507 299 65 19,695 5,672 10,533 1,278 487 5,441 1,378 556 3,052 2,503 311 9,453 3,321 4,398 245 190 2,308 553 2,017 546 304 3,150 1,319 1,880 241 663 380 1,331 365 122 2,588 379 1,042 122 373 124 627 122 674 309 1,011 188 1,505 99,913 1,065 65,712 441 41,911 364 50,595 311 23,030 304 9,329 122 5,377 - - 3,686 - - 100,978 66,153 42,276 50,905 23,333 9,451 5,377 3,686 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Species group Diameter class (inches) 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- 24.9 25.0- 28.9 29.0- 32.9 33.0- 36.9 37.0+ All classes Table 11—Number of growing stock trees on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. (In thousand trees).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 91 Forest Service Other Federal State and local government Private National forest National Park Service Bureau of Land Management Department of Defense or Energy State Undifferentiated private 30,911.7 - - 1,061.6 144.8 3,126.7 4,709.9 Table 12--Net volume of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. 353.0 - - 119.0 12.3 36.2 103.7 31,264.7 - - 1,180.6 157.2 3,162.9 4,813.6 6,486.9 55.2 - - - - 52.9 - - (Table 12 continued on next page) 39,954.8 624.2 40,579.0 6,594.9 All owners 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. 26.5 5.2 - - - - - - - - 6,513.3 60.4 - - - - 52.9 - - 37,778.0 60.4 1,180.6 157.2 3,215.8 4,813.6 31.7 6,626.6 47,205.6 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land Table 12—Net volume of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In million cubic feet).
92 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Woodland hardwoods group Nonstocked 165.9 14,383.8 3,084.0 103.9 15,870.4 2,809.6 4,041.9 716.3 500.8 165.6 233.4 - - 55.6 - - Table 13--Net volume of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 3.6 500.3 16.8 7.8 821.5 1,618.1 181.7 124.6 16.9 - - 349.3 - - 21.0 - - 0.8 295.1 28.9 0.8 573.6 158.4 21.0 24.2 26.9 - - 87.1 6.0 17.9 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 13 continued on next page) 42,131.3 3,661.7 1,240.8 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - - - 171.8 171.8 170.3 15,179.2 3,129.7 112.5 17,265.6 4,586.2 4,244.7 865.2 544.6 165.6 669.8 6.0 94.5 171.8 47,205.6 Large diameter Medium diameter Small diameter Stand-size class Forest-type group Chaparral Nonstocked All size classes Table 13—Net volume of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. (In million cubic feet). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Woodland hardwoods group Nonstocked 165.9 14,383.8 3,084.0 103.9 15,870.4 2,809.6 4,041.9 716.3 500.8 165.6 233.4 - - 55.6 - - Table 13--Net volume of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 3.6 500.3 16.8 7.8 821.5 1,618.1 181.7 124.6 16.9 - - 349.3 - - 21.0 - - 0.8 295.1 28.9 0.8 573.6 158.4 21.0 24.2 26.9 - - 87.1 6.0 17.9 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 13 continued on next page) 42,131.3 3,661.7 1,240.8 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - - - 171.8 171.8 170.3 15,179.2 3,129.7 112.5 17,265.6 4,586.2 4,244.7 865.2 544.6 165.6 669.8 6.0 94.5 171.8 47,205.6 Large diameter Medium diameter Small diameter Stand-size class Forest-type group Chaparral Nonstocked All size classes
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 93 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Western woodland hardwoods 10,916.4 2,240.8 10,375.3 642.5 178.1 3,570.0 806.5 5,222.7 2,063.8 61.0 1,341.6 275.6 5.7 31.9 46.3 Table 14--Net volume of all live trees on forest land by species group and ownership group, Idaho, cycle 2, 2004-2009. 549.8 35.3 244.2 35.5 11.0 19.3 32.2 60.7 35.2 70.8 178.3 76.8 17.0 5.3 26.7 678.1 178.9 1,110.0 84.0 85.2 245.2 158.8 135.3 392.0 0.7 61.9 65.2 - - 14.1 6.5 (Table 14 continued on next page) 37,778.0 1,398.1 3,215.8 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. 1,339.2 559.6 1,180.5 238.9 53.0 78.2 220.5 205.0 557.6 75.5 19.9 191.3 1.9 81.7 10.7 13,483.6 3,014.5 12,910.0 1,001.0 327.3 3,912.8 1,218.0 5,623.7 3,048.6 207.9 1,601.7 608.8 24.6 132.9 90.2 4,813.6 47,205.6 Softwood species groups Hardwood species groups 37,418.6 359.4 1,272.3 125.8 3,130.1 85.7 4,528.0 285.6 46,349.1 856.5 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 14—Net volume of all live trees on forest land by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
94 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Western woodland hardwoods 329 31 886 57 13 101 31 672 143 9 67 53 1 33 18 Table 15--Net volume of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. 622 62 1,183 102 19 168 70 1,193 148 15 139 107 1 31 22 1,024 106 1,365 113 18 219 118 1,277 175 22 168 110 1 30 15 1,387 146 1,413 111 28 310 145 1,049 184 25 177 111 5 24 12 (Table 15 continued on next page) 2,443 3,882 4,761 5,126 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. 1,581 177 1,366 125 31 370 163 662 164 22 160 54 8 7 9 13,484 3,015 12,910 1,001 327 3,913 1,218 5,624 3,049 208 1,602 609 25 133 90 4,900 47,206 Softwood species groups Hardwood species groups 2,337 106 3,720 161 4,606 155 4,974 153 4,822 78 46,349 857 All softwoods All hardwoods 1,573 242 1,312 98 33 349 161 414 206 30 142 35 4 5 4 1,318 227 1,169 62 39 410 108 196 263 27 191 25 3 3 1,331 288 898 34 28 349 87 99 126 17 106 23 4 3 1,888 556 1,324 160 76 727 144 63 298 13 225 24 4 1,188 494 742 39 32 439 83 252 14 95 42 521 371 499 52 12 169 73 235 10 74 24 517 147 322 48 216 34 145 4 34 206 167 431 88 711 23 4,559 47 4,008 32 3,362 31 5,474 27 3,377 42 2,017 24 1,467 - - 1,626 - - 4,607 4,040 3,393 5,501 3,419 2,041 1,467 1,626 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Species group Diameter class (inches) 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- 24.9 25.0- 28.9 29.0- 32.9 33.0- 36.9 37.0+ All classes Table 15—Net volume of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 95

Pinyon / juniper group

Douglas-fir group

Ponderosa pine group

Western white pine group

Fir / spruce / mountain hemlock grou

Lodgepole pine group

Hemlock / Sitka spruce group

Western larch group

Other western softwoods group

Elm / ash / cottonwood group

Aspen / birch group

Alder / maple group

Woodland hardwoods group

Nonstocked

 170.3

 15,148.2

 3,071.1

 112.5

 17,265.0

 4,579.9

 4,244.7

 863.1

 544.6

 165.6

 667.1

 6.0

 94.5

 171.8

Table 16--Net volume of all live trees on forest land by forest type group and stand origin,

 

 - -

 31.0

 58.5

 - -

 0.5

 6.3

 - -

 2.1

 - -

 - -

 2.7

 - -

 - -

 - -

(Table 7 continued on next page)

All forest-type groups 47,104.3 101.2

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.

 170.3

 15,179.2

 3,129.7

 112.5

 17,265.6

 4,586.2

 4,244.7

 865.2

 544.6

 165.6

 669.8

 6.0

 94.5

 171.8

 47,205.6

Natural

stands

Artificial

 regeneration

Stand origin

 Forest-type group

All forest

land

Table 16—Net volume of all live trees on forest land by forest type group and stand origin, Idaho, cycle 

2, 2004-2009.

(In million cubic feet).

Pinyon / juniper group

Douglas-fir group

Ponderosa pine group

Western white pine group

Fir / spruce / mountain hemlock grou

Lodgepole pine group

Hemlock / Sitka spruce group

Western larch group

Other western softwoods group

Elm / ash / cottonwood group

Aspen / birch group

Alder / maple group

Woodland hardwoods group

Nonstocked

 165.9

 14,383.8

 3,084.0

 103.9

 15,870.4

 2,809.6

 4,041.9

 716.3

 500.8

 165.6

 233.4

 - -

 55.6

 - -

Table 13--Net volume of all live trees on forest land by forest type group and stand-size class, 

 

 3.6

 500.3

 16.8

 7.8

 821.5

 1,618.1

 181.7

 124.6

 16.9

 - -

 349.3

 - -

 21.0

 - -

 0.8

 295.1

 28.9

 0.8

 573.6

 158.4

 21.0

 24.2

 26.9

 - -

 87.1

 6.0

 17.9

 - -

All forest-type groups 42,131.3 3,661.7 1,240.8 

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.

Large

diameter

Medium

 diameter

Small

diameter

Stand-size class

 Forest-type group Chap
96 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods 273 28 722 56 13 80 31 478 139 43 40 1 32 Table 17--Net volume of growing-stock trees on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. 509 54 973 102 19 135 70 912 145 98 88 1 31 866 95 1,151 112 18 169 117 935 174 124 100 1 30 1,145 132 1,226 111 28 245 145 813 183 136 103 5 24 (Table 17 continued on next page) 1,935 3,137 3,892 4,297 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. 1,362 156 1,191 123 31 275 163 536 160 127 51 8 7 11,544 2,464 11,157 998 301 2,949 1,217 4,288 2,818 1,261 545 25 132 4,189 39,697 Softwood species groups Hardwood species groups 1,862 74 3,016 121 3,761 131 4,164 133 4,124 65 38,996 701 All softwoods All hardwoods 1,396 216 1,178 97 33 231 161 316 194 117 32 4 5 1,135 194 1,058 62 39 326 108 164 256 163 17 3 1,148 223 767 34 28 249 87 82 118 79 23 4 1,545 496 1,132 160 61 582 144 52 256 196 24 1,045 407 664 39 32 363 83 248 71 42 461 260 418 52 128 73 211 74 24 489 79 252 48 93 34 145 34 171 124 424 73 590 3,940 41 3,504 20 2,815 27 4,625 24 2,951 42 1,677 24 1,175 - - 1,382 - - 3,980 3,524 2,842 4,648 2,994 1,702 1,175 1,382 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Species group Diameter class (inches) 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- 24.9 25.0- 28.9 29.0- 32.9 33.0- 36.9 37.0+ All classes Table 17—Net volume of growing stock trees on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 97 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods 9,003.8 1,692.2 8,649.7 642.2 177.7 2,618.6 805.4 3,933.8 1,838.8 1,061.9 241.0 5.7 31.2 535.1 35.2 236.7 35.5 11.0 14.1 32.2 15.3 35.2 151.4 72.1 17.0 5.3 673.6 178.3 1,091.0 82.3 58.8 238.0 158.8 134.7 391.7 36.0 59.8 - - 13.8 (Table 18 continued on next page) 30,702.0 1,196.1 3,116.8 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. 1,331.4 558.7 1,179.2 237.6 53.0 78.2 220.5 204.4 552.6 11.5 171.8 1.9 81.6 11,543.9 2,464.3 11,156.6 997.6 300.5 2,949.0 1,216.9 4,288.2 2,818.3 1,260.8 544.7 24.6 131.8 4,682.4 39,697.2 Softwood species groups Hardwood species groups 30,424.1 277.8 1,101.7 94.4 3,043.2 73.6 4,427.1 255.3 38,996.1 701.1 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 18—Net volume of growing stock trees on timberland by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
98 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Table 19--Net volume of sawtimber trees (International 1/4-inch rule) on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. 3,410 190 5,561 488 90 936 633 5,318 848 564 5,316 571 6,537 569 155 1,397 799 4,495 947 678 524 29 126 (Table 19 continued on next page) 18,038 22,142 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. 6,915 846 6,728 686 181 1,588 924 2,947 869 673 261 44 37 59,601 16,256 56,471 4,796 1,677 16,370 6,443 16,057 14,167 6,246 1,614 111 201 22,699 200,010 Softwood species groups Hardwood species groups 18,038 - - 21,464 679 22,357 342 198,084 1,926 All softwoods All hardwoods 7,522 1,333 6,953 565 200 1,349 936 1,722 1,061 636 166 23 23 6,366 1,276 6,453 368 246 1,904 637 869 1,434 930 86 15 6,683 1,529 4,822 207 181 1,446 521 430 663 449 118 14 9,318 3,499 7,334 1,011 402 3,497 871 276 1,456 1,194 129 6,604 3,086 4,378 248 221 2,328 496 1,428 428 213 3,011 2,154 2,811 338 822 428 1,228 477 117 3,286 663 1,782 315 623 199 823 217 1,169 1,108 3,112 481 3,411 22,277 213 20,482 101 16,932 132 28,857 129 19,217 213 11,269 117 7,910 - - 9,280 - - 22,490 20,583 17,065 28,986 19,430 11,386 7,910 9,280 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Species group Diameter class (inches) 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- 24.9 25.0- 28.9 29.0- 32.9 33.0- 36.9 37.0+ All classes Table 19—Net volume of sawtimber trees (International 1/4 inch rule) on timberland by species group and diameter class, Idaho, cycle 2, 2004-2009. (In million board feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 99 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods 7,687.6 1,526.8 6,615.9 488.3 150.6 2,208.3 684.6 2,403.7 1,504.9 813.2 78.1 3.3 9.8 450.9 31.8 194.4 27.8 10.4 12.0 28.4 7.0 29.9 130.3 39.0 12.6 - - 547.5 151.6 863.2 59.1 52.3 203.0 127.7 106.1 295.3 32.6 23.7 - - 1.7 (Table 20 continued on next page) 24,175.0 974.5 2,463.8 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. 1,071.2 476.6 842.1 132.7 40.7 54.6 163.6 136.0 355.8 9.3 104.2 - - 16.9 9,757.2 2,186.8 8,515.6 707.9 254.1 2,477.8 1,004.3 2,652.8 2,185.7 985.4 245.0 15.9 28.3 3,403.8 31,017.1 Softwood species groups Hardwood species groups 24,083.8 91.2 922.9 51.7 2,438.5 25.3 3,282.7 121.1 30,727.8 289.2 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 20—Net volume of sawtimber trees on timberland by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
100 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Forest Service Other Federal State and local government Private National forest National Park Service Bureau of Land Management Department of Defense or Energy State Undifferentiated private 247.3 - - 18.9 4.3 80.3 167.2 Table 21--Average annual net growth of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. -3.0 - - -0.2 0.0 0.6 1.7 244.4 - - 18.7 4.3 80.9 168.8 -138.9 0.9 - - - - 0.1 - - (Table 21 continued on next page) 518.0 -0.8 517.1 -138.0 All owners 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. -3.2 0.2 - - - - - - - - -142.2 1.1 - - - - 0.1 - - 102.2 1.1 18.7 4.3 80.9 168.8 -3.0 -141.0 376.2 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land Table 21—Average annual net growth of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 101 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Woodland hardwoods group Nonstocked 1.4 176.9 40.9 2.3 183.5 11.5 64.2 13.2 0.2 3.9 7.4 - - 0.9 - - Table 22--Average annual net growth of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 0.1 16.7 1.4 1.1 25.6 14.2 10.7 6.9 0.1 - - 11.1 - - 0.3 - - 0.0 4.1 -1.3 0.1 7.1 -25.5 -3.0 0.0 -1.3 - - -6.1 0.7 0.6 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 22 continued on next page) 506.2 88.1 -24.4 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - - - -193.8 -193.8 1.5 197.6 41.0 3.6 216.1 0.3 71.8 20.1 -1.0 3.9 12.4 0.7 1.9 -193.8 376.2 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest-type group Non stocked All size classes Table 22—Average annual net growth of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. (In million cubic feet). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Alder / maple group Woodland hardwoods group Nonstocked 165.9 14,383.8 3,084.0 103.9 15,870.4 2,809.6 4,041.9 716.3 500.8 165.6 233.4 - - 55.6 - - Table 13--Net volume of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. 3.6 500.3 16.8 7.8 821.5 1,618.1 181.7 124.6 16.9 - - 349.3 - - 21.0 - - 0.8 295.1 28.9 0.8 573.6 158.4 21.0 24.2 26.9 - - 87.1 6.0 17.9 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 13 continued on next page) 42,131.3 3,661.7 1,240.8 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - - - 171.8 171.8 170.3 15,179.2 3,129.7 112.5 17,265.6 4,586.2 4,244.7 865.2 544.6 165.6 669.8 6.0 94.5 171.8 47,205.6 Large diameter Medium diameter Small diameter Stand-size class Forest-type group Chaparral Nonstocked All size classes
102 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Western woodland hardwoods -14.8 12.0 96.5 15.7 0.1 31.2 10.6 -80.1 30.1 0.7 -7.8 6.3 0.2 0.4 0.9 10.0 0.5 6.6 0.9 -0.1 0.2 0.3 0.5 1.2 -1.3 2.8 1.2 0.5 0.5 0.4 13.7 5.7 35.1 3.0 0.2 4.8 3.3 0.3 12.4 0.0 1.1 1.3 - - -0.1 0.1 (Table 23 continued on next page) 102.2 24.2 80.9 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. 47.3 16.2 49.7 10.4 2.6 3.2 5.3 3.9 20.6 0.9 0.4 4.3 0.3 3.3 0.3 56.3 34.4 188.0 30.0 2.8 39.5 19.6 -75.3 64.4 0.2 -3.6 13.1 1.0 4.1 1.7 168.8 376.2 Softwood species groups Hardwood species groups 94.4 7.8 21.5 2.7 79.7 1.2 160.6 8.2 356.2 19.9 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 23—Average annual net growth of all live trees on forest land by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 103 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Red alder Other western hardwoods 67.2 17.3 114.4 15.7 0.1 32.3 10.7 -50.1 29.0 4.2 6.0 0.2 0.4 Table 24--Average annual net growth of growing-stock trees on timberland by species group and ownership group, Idaho, cycle 2, 2004-2009. 9.8 0.5 6.6 0.9 -0.1 0.2 0.3 -0.5 1.2 2.1 1.0 0.5 0.5 13.5 5.7 34.7 2.9 -0.4 6.0 3.3 0.3 12.4 0.7 1.1 - - -0.1 (Table 24 continued on next page) 247.4 23.0 80.1 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. 47.1 16.1 49.7 10.3 2.6 3.2 5.3 3.8 20.5 0.3 3.8 0.3 3.3 137.6 39.5 205.4 29.9 2.2 41.6 19.7 -46.6 63.1 7.2 12.0 1.0 4.1 166.3 516.6 Softwood species groups Hardwood species groups 240.8 6.6 20.9 2.1 79.0 1.0 158.8 7.4 499.5 17.1 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 24—Average annual net growth of growing stock trees on timberland by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
104 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Forest Service Other Federal State and local government Private National forest National Park Service Bureau of Land Management Department of Defense or Energy State Undifferentiated private 483.8 - - 4.8 0.2 22.1 25.7 Table 25--Average annual mortality of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. 10.8 - - 1.9 - - 0.1 0.2 494.6 - - 6.7 0.2 22.2 25.9 259.7 0.2 - - - - 1.6 - - (Table 25 continued on next page) 536.5 13.0 549.5 261.4 All owners 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. 3.6 - - - - - - - - - - 263.3 0.2 - - - - 1.6 - - 757.9 0.2 6.7 0.2 23.8 25.9 3.6 265.0 814.6 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land Table 25—Average annual mortality of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 105 Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Woodland hardwoods group Nonstocked 0.3 150.5 24.9 2.1 197.1 49.3 26.1 8.3 5.8 0.0 0.4 - - - - - - 7.3 - - - - 15.9 40.6 0.1 0.5 0.4 - - 1.9 0.0 - - - - 9.2 2.4 - - 20.6 34.4 4.5 0.7 2.0 - - 9.8 0.0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 26 continued on next page) 465.1 66.8 83.6 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - 199.1 199.1 0.3 167.0 27.3 2.1 233.6 124.3 30.8 9.5 8.3 0.0 12.2 0.0 199.1 814.6 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest-type group Non stocked All size classes Table 26—Average annual mortality of all live trees on forest land by forest type group and stand-size class, Idaho, cycle 2, 2004-2009. (In million cubic feet). Pinyon / juniper group Douglas-fir group Ponderosa pine group Western white pine group Fir / spruce / mountain hemlock grou Lodgepole pine group Hemlock / Sitka spruce group Western larch group Other western softwoods group Elm / ash / cottonwood group Aspen / birch group Woodland hardwoods group Nonstocked 0.3 150.5 24.9 2.1 197.1 49.3 26.1 8.3 5.8 0.0 0.4 - - - - - - 7.3 - - - - 15.9 40.6 0.1 0.5 0.4 - - 1.9 0.0 - - - - 9.2 2.4 - - 20.6 34.4 4.5 0.7 2.0 - - 9.8 0.0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 26 continued on next page) 465.1 66.8 83.6 - - All forest-type 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. - - - - - - - - - - - - - - - - - - - - - - - - 199.1 199.1 0.3 167.0 27.3 2.1 233.6 124.3 30.8 9.5 8.3 0.0 12.2 0.0 199.1 814.6 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest-type group Non stocked All size classes
106 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods 228.7 25.3 210.9 1.9 6.2 33.8 5.6 202.5 6.6 0.2 32.2 3.1 0.7 0.2 2.2 0.2 0.9 - - 0.3 - - - - 0.9 - - 1.9 0.6 0.0 - - 0.0 7.6 0.0 7.6 0.0 2.1 2.3 0.3 2.7 0.1 - - 0.1 0.5 0.6 - - (Table 27 continued on next page) 757.9 7.1 23.8 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. 2.3 2.8 12.6 0.0 0.3 0.2 0.5 3.1 2.5 - - - - 1.1 0.4 - - 240.7 28.3 232.0 2.0 8.9 36.3 6.4 209.2 9.2 2.2 32.9 4.7 1.6 0.2 25.9 814.6 Softwood species groups Hardwood species groups 753.9 4.0 7.0 0.0 22.7 1.0 24.4 1.5 808.0 6.5 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 27—Average annual mortality of all live trees on forest land by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 107 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Other western softwoods Cottonwood and aspen Other western hardwoods 112.8 14.0 150.2 1.9 6.2 19.2 5.5 145.7 5.1 16.8 2.2 0.7 2.2 0.2 0.8 - - 0.3 - - - - 0.9 - - 0.6 0.0 - - 7.6 - - 7.3 0.0 2.1 1.0 0.3 2.7 0.1 0.1 0.4 0.6 (Table 28 continued on next page) 480.2 4.9 22.0 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. 2.3 2.8 12.6 0.0 0.3 0.2 0.5 3.1 2.5 - - 0.8 0.4 124.8 17.0 170.8 2.0 8.9 20.4 6.3 152.3 7.7 17.5 3.5 1.6 25.6 532.7 Softwood species groups Hardwood species groups 477.3 2.9 4.9 0.0 21.1 1.0 24.4 1.2 527.6 5.1 All softwoods All hardwoods Forest Service Other Federal State and local government Species group Undifferentiated private All owners Ownership group Table 28—Average annual mortality of growing stock trees on timberland by species group and ownership group, Idaho, cycle 2, 2004-2009. (In million cubic feet).
108 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 All Owner class Timberland Unproductive Total Productive Unproductive Total forest land Forest Service National Forest 552,941 8,845 561,786 115,021 586 115,608 677,394 Other Federal National Park Service - - - - - - 1,204 121 1,325 1,325 Bureau of Land Management 20,056 3,365 23,421 - - - - - - 23,421 Department of Defense or Energy 2,389 225 2,615 - - - - - - 2,615 State and local government State 54,460 942 55,402 918 - - 918 56,320 Private Undifferentiated private 88,925 2,595 91,520 - - - - - - 91,520 All owners 718,772 15,972 734,744 117,144 707 117,850 852,595 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 29a--Aboveground dry weight (regional equations method) of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In thousand dry tons) Unreserved forests Reserved forests Table 29a—Aboveground dry weight (regional equations method) of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In thousand dry tons).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 109 Forest Service Other Federal State and local government Private National forest National Park Service Bureau of Land Management Department of Defense or Energy State Undifferentiated private 543,198 - - 19,975 2,546 54,136 86,429 Table 29b--Aboveground dry weight (component ratio method) of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. 7,637 - - 2,658 250 755 2,363 550,834 - - 22,633 2,796 54,890 88,792 112,207 1,067 - - - - 844 - - (Table 31 continued on next page) 706,283 13,663 719,946 114,118 All owners 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. 502 109 - - - - - - - - 112,709 1,176 - - - - 844 - - 663,544 1,176 22,633 2,796 55,735 88,792 612 114,730 834,676 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land Table 29b—Aboveground dry weight (component ratio method) of all live trees by owner class and forest land status, Idaho, cycle 2, 2004-2009. (In thousand dry tons).
110 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 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- All Species group 2.9 4.9 6.9 8.9 10.9 12.9 14.9 16.9 18.9 20.9 21.0-22.9 24.9 26.9 28.9 29.0+ classes Softwood species groups Western softwood species groups Douglas-fir 2,543 5,229 7,979 13,495 21,054 27,487 30,661 30,309 25,104 25,153 21,012 14,730 13,419 8,903 23,361 270,438 Ponderosa and Jeffrey pine 293 592 950 1,258 2,009 2,696 3,322 4,546 4,259 5,418 5,203 5,355 6,566 2,986 13,313 58,765 True fir 7,567 11,069 15,513 19,424 21,444 21,694 20,715 19,732 17,487 13,371 11,310 8,684 6,358 4,850 19,554 218,771 Western hemlock 708 952 1,293 2,020 2,085 1,997 2,175 1,708 1,064 569 1,484 1,205 301 366 1,668 19,595 Western white pine 175 371 299 321 278 424 475 517 614 442 447 798 312 215 211 5,900 Engelmann and other spruces 724 1,229 1,781 2,707 3,323 4,564 5,324 4,908 5,700 4,794 5,587 4,292 3,021 2,893 6,399 57,246 Western larch 85 186 698 1,435 2,324 2,763 3,087 3,065 2,019 1,619 1,862 833 955 591 1,992 23,515 Lodgepole pine 2,317 5,400 13,567 19,042 19,705 16,272 10,405 6,242 2,967 1,490 931 - - - - - - - - 98,338 Western redcedar 1,052 1,529 2,304 2,302 2,599 2,622 2,280 2,842 3,519 1,733 1,959 1,998 1,466 1,881 14,359 44,448 Western woodland softwoods 35 93 193 316 432 469 407 554 475 310 134 103 131 121 239 4,013 Other western softwoods 1,131 1,931 1,839 2,791 3,152 3,275 2,939 2,577 3,390 1,867 2,749 1,266 776 884 2,300 32,868 All softwoods 16,631 28,582 46,417 65,112 78,404 84,264 81,789 77,000 66,597 56,767 52,679 39,264 33,305 23,690 83,396 833,897 Hardwood species groups Western hardwood species groups Cottonwood and aspen 433 519 905 1,834 1,905 1,949 954 604 404 347 197 139 449 126 318 11,081 Red alder 13 7 24 25 14 99 139 69 - - 95 - - - - - - - - - - 486 Other western hardwoods 26 44 585 551 536 445 126 85 53 - - - - - - - - - - - - 2,451 Western woodland hardwoods 445 640 689 839 609 482 348 152 144 157 116 60 - - - - - - 4,681 All hardwoods 917 1,210 2,204 3,249 3,064 2,975 1,567 910 601 598 312 199 449 126 318 18,698 All species groups 17,547 29,792 48,621 68,360 81,468 87,239 83,356 77,909 67,198 57,365 52,991 39,464 33,754 23,816 83,714 852,595 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 30a--Aboveground dry weight (regional equations method) of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (In thousand dry tons) Diameter class (inches) Table 30a—Aboveground dry weight (regional equations method) of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (In thousand dry tons).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 111 Western softwood species groups Western hardwood species groups Table 30b--Aboveground dry weight (component ratio method) of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (Table 32 continued on next page) 41,515 65,630 80,671 87,478 All species groups 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. 84,403 834,676 Softwood species groups Hardwood species groups 39,245 2,270 62,467 3,164 77,723 2,948 84,676 2,802 83,050 1,353 815,333 19,343 All softwoods All hardwoods 78,518 794 68,392 516 58,296 495 53,886 237 39,992 162 33,585 481 24,117 156 83,197 369 79,313 68,908 58,791 54,124 40,154 34,067 24,273 83,566 20,342 1,971 22,312 7,846 1,625 9,471 Species group Diameter class (inches) 29.0+ All classes 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- 18.9 19.0- 20.9 21.0- 22.9 23.0- 24.9 25.0- 26.9 27.0- 28.9 26,170 4,007 17,881 1,161 614 5,971 2,149 3,048 3,453 452 3,486 401 62 54 26,283 5,074 13,701 636 441 5,066 1,711 1,533 1,653 289 1,909 370 68 56 21,873 4,769 11,508 1,635 416 5,943 1,962 969 1,926 103 2,782 196 41 15,281 5,001 8,752 1,358 772 4,585 881 1,960 110 1,292 142 20 14,052 5,939 6,406 338 292 3,212 980 1,441 145 780 481 9,246 2,714 4,923 392 207 3,114 638 1,832 126 925 156 24,293 11,942 19,316 1,870 185 6,783 2,094 14,107 239 2,369 369 273,005 53,516 206,884 20,153 5,475 58,180 24,525 96,956 42,028 3,800 30,812 12,286 483 3,411 3,163 1,225 87 3,229 351 67 259 52 1,520 674 39 343 696 32 63 834 3,261 260 7,127 791 212 724 170 5,507 1,252 96 941 912 11 135 912 6,923 575 13,595 1,128 215 1,567 645 11,127 1,998 155 1,316 1,082 28 883 277 20,807 1,925 20,514 2,173 287 3,267 2,405 20,414 2,362 402 3,166 2,003 14 700 230 12,798 1,145 17,969 1,991 312 2,541 1,440 19,326 2,019 268 2,658 2,030 28 766 340 27,904 2,615 21,283 2,121 445 4,595 2,920 16,606 2,453 443 3,291 1,967 94 553 188 31,604 3,163 20,746 2,367 488 5,444 3,266 10,430 2,180 403 2,959 916 138 151 147 31,285 4,299 19,935 1,841 519 5,109 3,212 6,475 2,719 530 2,595 564 69 98 63 Douglas-fir Ponderosa and Jeffrey pines True fir Western hemlock Western white pine Engelmann and other spruces Western larch Lodgepole pine Western redcedar Western woodland softwoods Other western softwoods Cottonwood and aspen Red alder Other western hardwoods Western woodland hardwoods - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Table 30b—Aboveground dry weight (component ratio method) of all live trees on forest land by species group and diameter class, Idaho, cycle 2, 2004-2009. (In thousand dry tons).
112 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington 402.6 976.2 670.0 1,428.4 2,403.4 523.8 364.8 67.3 122.7 1,528.8 9.6 458.8 800.6 444.3 46.6 224.4 1,376.6 82.2 Table 31--Area of accessible forest land by Forest Survey Unit, county and forest land status, Idaho, cycle 2, 2004-2009. - - - - - - - - 21.2 12.8 - - - - - - - - - - - - 9.9 18.1 - - 180.6 10.7 - - 402.6 976.2 670.0 1,428.4 2,424.5 536.6 364.8 67.3 122.7 1,528.8 9.6 458.8 810.5 462.4 46.6 405.0 1,387.3 82.2 9.8 - - 21.5 - - 1,955.7 - - - - - - - - - - - - 22.3 9.9 48.8 - - - - 614.4 - - - - - - - - - - 21.2 - - - - - - - - - - - - - - - - - - - - - - 21.3 - - 9.8 - - 21.5 - - 1,976.9 - - - - - - - - - - - - 22.3 9.9 48.8 - - - - 635.7 - - 412.4 976.2 691.6 1,428.4 4,401.4 536.6 364.8 67.3 122.7 1,528.8 9.6 481.0 820.4 511.3 46.6 405.0 2,023.0 82.2 Timberland Unproductive Total Productive Unreserved forests Forest Survey Unit and county Reserved forests Unproductive Total All forest land (Table 31 continued on next page) 8,488.2 3,443.0 34.0 219.3 8,522.2 3,662.4 1,987.1 695.4 Total Total 21.2 21.3 2,008.3 716.7 10,530.4 4,379.1 Table 31— Northern SouthwesternArea of accessible forest land by Forest Survey Unit, county and forest land status, Idaho, cycle 2, 2004-2009. (In thousand acres).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 113 Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls 74.9 155.5 23.3 321.4 391.1 59.5 206.4 342.6 45.5 216.2 952.6 60.0 436.4 10.4 1,153.7 47.0 32.5 43.6 105.7 7.4 103.2 8.7 24.9 17.2 33.5 71.6 9.2 72.4 216.9 7.6 94.1 51.6 19.8 - - 145.5 - - 54.9 12.8 - - 7.4 178.0 164.2 48.2 338.5 424.5 131.0 215.6 415.0 262.4 223.8 1,046.7 111.6 456.2 10.4 1,299.1 47.0 87.4 56.4 105.7 14.7 - - - - - - - - - - - - - - - - - - - - 359.7 - - 61.6 - - 377.4 - - - - - - - - - - (Table 31 continued) 16,616.8 1,204.5 17,821.3 3,481.1 All counties - - - - - - - - - - 8.8 - - - - - - - - - - - - 10.3 - - 25.6 - - - - - - - - - - - - - - - - - - - - 8.8 - - - - - - - - 359.7 - - 71.8 - - 403.1 - - - - - - - - - - 178.0 164.2 48.2 338.5 424.5 139.8 215.6 415.0 262.4 223.8 1,406.4 111.6 528.0 10.4 1,702.2 47.0 87.4 56.4 105.7 14.7 87.2 3,568.3 21,389.6 Timberland Unproductive Total Productive Unreserved forests Forest Survey Unit and county Reserved forests Unproductive Total All forest land (Table 54 continued on next page) 4,685.6 951.2 5,636.8 798.7 Total 44.7 843.4 6,480.1 Southeastern 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.
114 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington 60.3 168.8 78.0 278.6 34.2 19.5 52.7 - - 44.5 76.6 9.4 39.6 90.7 9.6 - - 64.5 53.3 21.2 Table 32--Area of accessible forest land by Forest Survey Unit, county, ownership group and forest land status, Idaho, cycle 2, 2004-2009. 9.8 - - 21.5 - - - - - - - - - - - - - - - - - - - - 10.5 - - 49.4 - - - - 273.5 328.3 86.1 402.0 220.7 254.6 155.8 67.3 67.1 311.9 0.2 44.0 66.9 32.0 2.7 17.4 80.3 - - - - - - - - - - - - 12.8 - - - - - - - - - - - - - - - - - - 22.3 - - - - 412.4 976.2 691.6 1,428.4 4,401.4 536.6 364.8 67.3 122.7 1,528.8 9.6 481.0 820.4 511.3 46.6 405.0 2,023.0 82.2 (Table 32 continued on next page) 813.3 288.3 31.4 59.9 2,167.3 243.6 12.8 22.3 Total Total 10,530.4 4,379.1 All forest land Timber- land Other forest land Timber- land Other forest land Forest Service Timber- land Other forest land Timber- land Other forest land Other Federal State and local government Undifferentiated private 59.0 459.4 495.1 726.3 2,087.6 230.3 156.2 - - - - 1,079.7 - - 365.3 633.0 393.1 43.9 - - 1,243.0 61.0 - - - - - - - - 1,998.1 - - - - - - - - - - - - 22.3 19.8 56.5 - - - - 646.4 - - 9.8 19.7 10.8 21.5 60.9 19.5 - - - - 11.1 60.6 - - 9.9 9.9 9.6 - - 142.5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 108.9 - - - - 5,293.7 2,739.2 1,998.1 744.9 213.9 171.9 - - 108.9 Table 32— Forest Survey Unit and county Northern SouthwesternArea of accessible forest land by Forest Survey Unit, county, ownership group and forest land status, Idaho, cycle 2, 2004-2009. (In thousand acres).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 115 Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls - - - - - - 7.4 11.5 - - 9.2 33.4 - - 9.6 - - - - - - - - 2.5 7.8 - - - - - - - - 9.9 - - 5.0 - - - - - - - - - - 10.2 - - - - - - - - - - - - - - - - - - - - - - 18.5 8.7 23.3 39.6 8.4 - - 9.2 12.3 - - - - - - - - 20.4 - - 10.3 - - 10.0 - - - - - - 50.5 - - 20.0 9.8 18.6 - - 3.9 20.2 30.6 - - - - 22.9 - - - - - - - - 17.5 10.3 - - - - (Table 32 continued) 1,183.2 116.3 2,571.6 239.2 All counties 178.0 164.2 48.2 338.5 424.5 139.8 215.6 415.0 262.4 223.8 1,406.4 111.6 528.0 10.4 1,702.2 47.0 87.4 56.4 105.7 14.7 21,389.6 (Table 55 continued on next page) 81.6 25.1 160.7 204.1 Total 6,480.1 All forest land Timber- land Other forest land Timber- land Other forest land Forest Service Timber- land Other forest land Timber- land Other forest land Other Federal State and local government Undifferentiated private 26.7 146.9 - - 264.5 365.2 51.7 177.5 276.7 45.5 196.5 917.2 60.0 416.0 - - 1,074.0 39.2 20.0 12.8 96.1 7.4 42.8 8.7 - - 7.4 14.9 41.4 5.4 31.9 71.0 7.6 423.0 28.7 7.4 - - 540.8 - - 15.0 - - - - 7.4 29.7 - - - - 9.9 6.0 7.8 10.4 20.2 - - 10.1 35.5 - - - - 10.4 66.8 - - 2.5 30.8 9.6 - - - - - - - - - - - - 38.9 - - 20.3 105.1 - - 30.8 - - 84.2 - - 7.7 - - 22.5 2.6 - - - - 4,193.8 1,253.3 249.5 312.1 12,226.7 3,996.3 635.3 421.0 Forest Survey Unit and county Southeastern 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.
116 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington 295.3 615.2 409.0 887.8 1,761.1 400.3 228.2 39.4 69.9 1,209.8 9.6 361.3 594.8 275.1 43.9 104.1 1,004.0 82.2 Table 33--Area of timberland by Forest Survey Unit, county and stand-size class, Idaho, cycle 2, 2004-2009. 17.2 158.9 148.0 134.5 212.1 14.6 33.4 - - 30.6 131.3 - - 9.9 9.9 5.3 - - - - 103.8 - - 90.1 179.9 99.6 338.0 306.6 77.9 81.9 8.3 22.2 187.7 - - 70.3 96.7 65.6 - - 27.3 148.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22.2 13.5 68.0 123.6 31.0 21.3 19.6 - - - - - - 17.3 99.2 98.3 2.7 93.0 120.0 - - 402.6 976.2 670.0 1,428.4 2,403.4 523.8 364.8 67.3 122.7 1,528.8 9.6 458.8 800.6 444.3 46.6 224.4 1,376.6 82.2 (Table 33 continued on next page) 5,916.1 2,475.0 880.6 128.9 1,392.3 408.7 - - - - Total Total 299.2 430.5 8,488.2 3,443.0 Forest Survey Unit and county Stand-size class Chaparral All size classes Small diameter Medium diameter Large diameter Nonstocked Table 33— Northern SouthwesternArea of timberland by Forest Survey Unit, county and stand-size class, Idaho, cycle 2, 2004-2009. (In thousand acres).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 117 Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls 45.1 97.4 10.0 239.5 264.3 51.7 169.2 199.5 41.3 161.9 621.3 49.6 200.1 10.4 683.3 18.3 22.5 28.2 62.5 - - 22.5 34.7 10.0 39.8 37.8 7.8 13.8 60.0 - - 19.3 158.1 10.4 103.9 - - 222.8 10.4 - - 10.3 - - 7.4 7.3 23.4 3.3 32.1 63.1 - - 20.8 80.2 2.5 25.0 75.3 - - 124.7 - - 159.2 7.8 10.0 - - 43.3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 33 continued) 11,367.1 1,778.6 2,479.0 - - All counties - - - - - - 9.9 26.0 - - 2.6 2.8 1.6 10.1 98.0 - - 7.7 - - 88.3 10.4 - - 5.1 - - - - 74.9 155.5 23.3 321.4 391.1 59.5 206.4 342.6 45.5 216.2 952.6 60.0 436.4 10.4 1,153.7 47.0 32.5 43.6 105.7 7.4 992.2 16,616.8 (Table 57 continued on next page) 2,975.9 769.1 678.0 - - Total 262.5 4,685.6 Forest Survey Unit and county Stand-size class Chaparral All size classes Small diameter Medium diameter Large diameter Nonstocked Southeastern 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.
118 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington - - 22.4 13.5 68.0 134.2 31.0 21.3 19.6 - - - - 0.2 17.3 99.8 98.3 2.7 93.0 120.0 - - Table 34--Area of timberland by Forest Survey Unit, county, and stocking class, Idaho, cycle 2, 2004-2009. 188.0 320.9 180.3 392.7 767.0 169.5 133.9 39.4 77.9 393.1 9.4 164.2 431.6 178.1 - - 111.6 552.4 21.2 122.8 373.8 309.5 665.4 923.7 236.2 116.1 - - 41.7 696.1 - - 203.8 214.7 152.8 43.9 14.8 608.3 53.0 89.3 259.1 164.1 288.8 566.1 87.1 92.1 8.3 - - 411.9 - - 68.5 52.1 14.8 - - 5.0 93.2 8.0 2.5 - - 2.7 13.5 12.4 - - 1.5 - - 3.1 27.8 - - 4.9 2.5 0.2 - - - - 2.7 - - 402.6 976.2 670.0 1,428.4 2,403.4 523.8 364.8 67.3 122.7 1,528.8 9.6 458.8 800.6 444.3 46.6 224.4 1,376.6 82.2 Nonstocked Poorly stocked Moderately stocked Fully stocked Forest Survey Unit and county Stocking class of growing-stock trees Over- stocked All classes (Table 34 continued on next page) 310.0 431.3 2,662.8 1,468.4 3,485.3 1,291.4 1,966.8 241.6 Total Total 63.4 10.3 8,488.2 3,443.0 Table 34— Northern SouthwesternArea of timberland by Forest Survey Unit, county and stocking class, Idaho, cycle 2, 2004-2009. (In thousand acres).
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 119 Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls - - - - - - 10.2 26.0 - - 13.0 7.3 1.6 10.1 108.0 - - 7.7 - - 98.8 10.4 - - 5.1 - - - - 35.5 52.2 10.0 49.5 173.7 21.0 41.1 67.3 - - 101.6 329.6 39.1 184.8 - - 411.1 7.8 22.5 18.0 33.6 - - 25.3 58.6 10.0 204.3 125.1 8.8 109.6 153.6 28.6 77.5 386.5 20.9 177.4 - - 409.4 20.9 - - 2.6 52.9 - - 14.1 44.7 3.3 57.4 66.3 29.7 40.4 112.2 6.4 22.1 128.3 - - 51.2 10.4 205.7 - - 10.0 18.0 19.2 7.4 (Table 34 continued) 1,039.4 5,729.5 6,648.5 3,055.2 All counties - - - - - - - - - - - - 2.3 2.2 8.9 4.8 0.3 - - 15.4 - - 28.7 7.8 - - - - - - - - 74.9 155.5 23.3 321.4 391.1 59.5 206.4 342.6 45.5 216.2 952.6 60.0 436.4 10.4 1,153.7 47.0 32.5 43.6 105.7 7.4 144.2 16,616.8 Nonstocked Poorly stocked Moderately stocked Fully stocked Forest Survey Unit and county Stocking class of growing-stock trees Over- stocked All classes (Table 58 continued on next page) 298.1 1,598.3 1,871.9 846.8 Total 70.5 4,685.6 Southeastern 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.
120 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Table 35--Net volume of growing-stock and sawtimber (International 1/4-inch rule) on timberland by Forest Survey Unit, county, and major species group, Idaho, cycle 2, 2004-2009. Forest Survey Unit and county Pine Other softwoods Soft hardwoods Hard hardwoods Growing stock All species Pine Other softwoods Soft hardwoods Hard hardwoods All species Major species group Sawtimber Major species group Northern Southwestern 3,820.7 1,852.5 21,393.6 4,487.7 208.2 8.0 64.8 0.8 Total Total 25,487.4 6,348.9 18,910.0 10,546.7 110,232.7 24,146.3 512.1 33.6 315.3 3.5 129,970.0 34,730.1 (Table 35 continued on next page) Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington 149.4 239.5 345.6 495.3 1,536.9 173.4 187.9 19.3 56.0 617.4 3.8 338.3 561.9 145.9 27.7 - - 728.1 46.8 945.1 2,014.5 1,527.4 3,701.0 6,256.5 1,257.1 794.9 49.2 88.9 4,759.1 - - 861.0 792.0 378.1 160.3 69.2 2,015.2 211.8 2.2 123.6 15.6 25.8 25.2 14.3 1.3 - - - - 0.2 - - 4.6 0.1 1.4 - - 1.5 0.3 - - - - 42.2 13.6 - - - - 8.5 - - - - - - 0.5 - - - - 0.8 - - - - - - - - - - 1,096.7 2,419.8 1,902.1 4,222.1 7,818.6 1,453.3 984.1 68.5 144.9 5,377.2 3.8 1,204.0 1,354.7 525.3 188.0 70.8 2,743.7 258.6 796.1 1,205.1 1,424.9 2,630.1 7,520.9 937.1 952.5 113.4 287.1 3,042.7 20.2 2,103.7 3,535.3 870.3 184.6 - - 3,587.1 245.5 - - 199.3 68.9 - - - - 47.1 - - - - - - - - - - - - 3.5 - - - - - - - - - - 5,584.7 11,308.8 9,035.3 21,686.0 41,274.7 7,680.3 5,060.8 339.4 702.0 27,297.9 20.2 6,837.3 7,758.7 2,866.8 1,236.0 303.5 14,221.6 1,485.9 4,788.7 9,631.0 7,507.6 18,945.0 33,692.0 6,663.9 4,108.3 226.0 414.9 24,255.1 - - 4,712.9 4,219.9 1,990.6 1,051.4 296.6 10,634.5 1,240.4 - - 273.4 33.8 110.9 61.8 32.2 - - - - - - - - - - 20.7 - - 6.0 - - 6.9 - - - - (In million board feet) (In million cubic feet) Table 35—Net volume of growing stock and sawtimber (International 1/4 inch rule) on timberland by Forest Survey Unit, county, and major species group, Idaho, cycle 2, 2004-2009. 
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 121 (Table 35 continued) 7,402.5 31,593.6 605.7 95.4 All counties 39,697.2 35,560.9 162,522.9 1,447.5 478.5 200,009.8 Forest Survey Unit and county Pine Other softwoods Soft hardwoods Hard hardwoods Growing stock All species Pine Other softwoods Soft hardwoods Hard hardwoods All species Major species group Sawtimber Major species group Southeastern 1,729.3 5,712.3 389.6 29.8 Total 7,861.0 6,104.3 28,143.9 901.9 159.7 35,309.7 (Table 59 continued on next page) 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. Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls - - 31.9 0.3 122.9 100.0 13.6 26.2 76.9 33.6 59.3 305.9 16.5 267.5 - - 622.9 25.5 - - - - 26.2 - - 95.9 236.1 11.8 581.1 523.4 90.4 498.5 399.3 63.0 276.4 1,232.0 85.8 268.5 - - 1,163.8 2.1 26.1 59.8 98.5 - - 30.4 22.8 6.0 15.8 99.2 - - 1.7 96.2 0.5 1.4 2.3 5.8 19.3 46.7 2.2 2.4 2.7 13.8 1.5 18.7 - - - - - - 18.0 - - - - - - - - - - - - - - - - - - - - 11.8 - - - - - - - - - - 126.3 290.8 18.1 737.8 722.6 104.0 526.3 572.3 97.1 337.2 1,540.2 108.2 555.3 46.7 1,800.6 30.1 28.8 73.6 126.3 18.7 - - 125.3 - - 476.6 397.7 72.1 105.8 298.6 139.5 285.4 1,038.1 85.6 883.5 - - 1,976.4 125.2 - - - - 94.7 - - - - - - - - 97.3 - - - - - - - - - - - - - - - - - - - - 62.4 - - - - - - - - - - 591.7 1,373.0 50.6 3,426.6 3,342.9 526.5 2,819.3 2,300.3 445.0 1,756.4 7,051.8 548.5 2,344.9 186.4 7,405.3 133.4 118.3 303.4 533.5 52.0 531.4 1,223.1 26.9 2,800.3 2,685.9 454.3 2,713.5 1,824.4 305.5 1,471.0 6,013.7 457.5 1,411.6 - - 5,358.1 8.2 116.2 303.4 438.8 - - 60.3 24.6 23.7 52.4 259.3 - - - - 177.3 - - - - - - 5.4 49.8 186.4 8.4 - - 2.2 - - - - 52.0 (In million board feet) (In million cubic feet)
122 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Table 36--Average annual net growth of growing stock and sawtimber (International 1/4-inch rule) on timberland by Forest Survey Unit, county, and major species group, Forest Survey Unit and county Pine Other softwoods Soft hardwoods Hard hardwoods Growing stock All species Pine Other softwoods Soft hardwoods Hard hardwoods All species Major species group Sawtimber Major species group Northern Southwestern -0.9 14.8 452.2 15.5 6.6 0.3 1.1 0.0 Total Total 458.9 30.6 140.8 155.1 2,821.4 201.9 45.0 1.1 4.6 0.0 3,011.8 358.1 (Table 36 continued on next page) (In million cubic feet) (In million board feet) Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington 3.2 4.8 1.5 -1.9 -17.3 4.2 1.7 0.9 2.3 -0.3 0.2 7.1 10.3 2.7 0.7 - - -8.0 1.7 27.5 45.7 19.9 102.0 94.5 30.7 23.3 1.4 2.1 105.1 - - 16.9 11.3 -2.4 0.4 1.0 -14.6 2.8 0.0 4.3 0.3 1.0 0.7 0.3 0.0 - - - - 0.0 - - 0.2 0.0 0.0 - - 0.0 0.0 - - - - 0.8 0.2 - - - - 0.1 - - - - - - 0.0 - - - - 0.0 - - - - - - - - - - 30.7 55.5 21.9 101.1 77.8 35.3 24.9 2.3 4.4 104.9 0.2 24.3 21.6 0.3 1.2 1.0 -22.6 4.5 29.3 24.1 30.5 -17.4 -8.3 27.4 17.5 6.6 10.1 21.1 1.7 51.6 75.3 21.1 5.8 - - -12.5 12.2 - - 3.5 0.9 - - - - 0.2 - - - - - - - - - - - - 0.0 - - - - - - - - - - 193.2 327.6 161.3 545.1 642.4 245.0 139.4 15.0 20.0 722.8 1.7 164.2 149.8 23.2 16.1 4.3 -30.8 29.7 163.9 261.7 129.3 559.2 648.8 216.5 121.9 8.4 10.0 701.7 - - 111.7 74.5 2.0 10.3 4.2 -18.3 17.5 - - 38.2 0.7 3.3 1.9 0.9 - - - - - - - - - - 0.9 - - 0.1 - - 0.1 - - - - Table 36—Average annual net growth of growing stock and sawtimber (International 1/4 inch rule) on timberland by Forest Survey Unit, county, and major species group, Idaho, cycle 2, 2004-2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 123 (Table 36 continued) -10.3 509.8 15.0 2.1 All counties 516.6 218.1 3,311.4 73.7 14.4 3,617.6 Forest Survey Unit and county Pine Other softwoods Soft hardwoods Hard hardwoods Growing stock All species Pine Other softwoods Soft hardwoods Hard hardwoods All species Major species group Sawtimber Major species group Southeastern -24.2 42.1 8.2 1.0 Total 27.2 -77.9 288.2 27.6 9.8 247.7 (Table 60 continued on next page) (In million cubic feet) (In million board feet) Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls - - 0.5 0.0 1.0 0.3 0.1 -0.4 1.9 0.8 -2.4 -45.0 -1.9 13.8 - - 5.8 0.6 - - - - 0.7 - - 1.5 5.1 0.7 1.5 8.3 0.5 0.5 9.1 0.6 3.5 -5.9 1.9 6.6 - - 3.5 0.1 0.8 1.9 2.0 - - 0.4 0.3 0.1 0.7 1.8 - - 0.1 2.3 0.1 0.2 -0.1 0.0 0.9 0.4 0.1 0.3 0.1 0.4 0.0 0.3 - - - - - - 0.6 - - - - - - - - - - - - - - - - - - - - 0.5 - - - - - - - - - - 1.9 5.9 0.8 3.7 10.4 0.7 0.1 13.4 1.4 1.3 -51.0 0.0 21.4 0.4 9.9 0.9 0.9 2.3 2.7 0.3 - - 5.3 - - 8.1 2.9 0.6 -3.6 5.5 3.1 -12.7 -186.0 -10.4 55.7 - - 48.7 4.6 - - - - 0.3 - - - - - - - - 3.2 - - - - - - - - - - - - - - - - - - - - 6.6 - - - - - - - - - - 10.2 28.6 5.3 30.6 58.3 7.9 0.8 65.9 7.4 12.8 -193.4 -0.8 99.5 1.5 78.8 4.8 5.8 8.7 10.6 4.4 9.1 23.0 5.0 17.9 47.5 7.3 4.4 52.6 4.2 25.5 -7.4 9.5 43.2 - - 23.4 0.3 3.7 8.7 10.3 - - 1.1 0.4 0.4 1.4 7.8 - - - - 7.7 - - - - - - 0.1 0.6 1.5 0.1 - - 2.2 - - - - 4.4 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.
124 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 Northern Southwestern Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Table 37--Sampling errors by Forest Survey Unit and county for area of timberland, volume, average annual net growth, average annual removals, (Sampling error in percent) 51.13 17.50 20.90 31.89 12.76 29.75 41.24 100.00 88.15 16.50 - - 91.39 51.15 60.63 70.78 100.00 21.66 100.00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 55.47 21.04 23.55 36.36 13.40 34.61 48.37 100.00 91.82 19.40 - - 91.59 56.12 63.49 73.60 100.00 24.21 94.40 18.73 10.84 12.76 9.25 8.23 14.58 22.09 65.80 27.47 7.67 100.00 15.65 11.97 19.41 51.41 43.92 10.08 35.83 16.02 14.88 20.13 18.36 14.91 14.94 19.55 49.63 100.00 10.05 100.00 18.76 18.11 100.00 100.00 86.58 100.00 28.88 (Table 37 continued on next page) - - - - 8.33 18.27 - - - - 9.69 20.08 Total Total 3.96 6.51 5.88 34.93 6.12 2.95 4.61 2.49 1.56 5.63 7.45 34.07 17.86 2.23 100.00 6.32 4.78 7.96 43.58 12.08 2.18 26.12 6.58 2.95 5.09 2.49 4.65 6.13 7.45 34.07 17.86 2.23 100.00 6.95 5.09 9.05 43.58 19.72 5.33 26.12 16.90 9.37 10.85 8.14 7.47 13.47 20.14 62.00 23.23 6.84 100.00 14.88 10.79 18.02 50.36 36.41 8.92 31.86 16.94 13.22 23.24 16.95 22.40 15.82 19.58 50.36 90.88 10.92 100.00 24.74 19.80 100.00 100.00 97.07 74.90 35.02 1.05 2.22 1.68 3.26 3.52 5.87 6.54 89.46 Forest area Timberland area Volume Average annual net growth Average annual removals Average annual mortality Volume Average annual net growth Average annual removals Average annual mortality Growing stock Sawtimber Table 37— Forest Survey Unit and county Sampling errors by Forest Survey Unit and county for area of timberland, volume, average annual net growth, average annual removals, and average annual mortality on timberland, Idaho, cycle 2, 2004-2009. (Sampling error in percent)
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 125 Southeastern Bannock Bear Lake Bingham Blaine Bonneville Butte Camas Caribou Cassia Clark Custer Franklin Fremont Jefferson Lemhi Madison Oneida Power Teton Twin Falls - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 82.52 37.29 100.00 36.86 40.47 76.98 60.27 50.66 100.00 51.18 15.92 88.31 53.84 - - 25.63 83.45 - - - - 54.59 100.00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 100.00 - - 42.69 48.37 100.00 62.95 - - 100.00 54.76 17.30 99.54 51.51 - - 28.86 - - - - - - 63.35 100.00 (Table 37 continued) - - 6.54 - - 7.47 All counties 39.31 27.59 71.28 15.05 15.77 43.17 28.94 18.09 62.63 21.18 12.63 41.85 20.52 99.22 11.27 78.20 77.54 71.16 43.73 100.00 40.49 26.77 91.47 78.83 28.35 78.63 100.00 20.99 100.00 100.00 28.10 100.00 16.68 99.22 45.84 71.26 71.33 58.87 42.48 100.00 2.98 6.36 (Table 65 continued on next page) - - 11.35 - - 12.73 Total 5.51 35.78 12.67 7.21 40.28 6.79 7.43 16.91 12.44 8.33 15.34 12.95 3.66 25.58 6.38 99.22 3.29 41.84 30.40 38.86 25.45 71.80 28.04 9.15 62.51 6.96 7.89 31.90 13.50 9.99 40.21 12.99 6.87 38.22 8.69 99.22 5.99 41.84 53.62 42.47 25.45 100.00 37.05 23.70 75.19 13.27 14.52 46.01 26.33 15.95 63.59 19.73 11.29 41.18 17.26 99.22 10.25 68.44 78.65 62.22 42.76 100.00 49.40 21.04 90.67 100.00 29.60 80.39 100.00 18.36 100.00 100.00 23.01 100.00 15.23 99.22 71.43 67.34 74.23 54.05 36.42 100.00 2.06 2.92 4.92 65.17 0.93 1.37 2.64 8.00 Forest area Timberland area Volume Average annual net growth Average annual removals Average annual mortality Volume Average annual net growth Average annual removals Average annual mortality Growing stock SawtimbeForest Forest Survey Unit and county Sampling errors that exceed 100% are reported as 100%. Northern Southwestern Benewah Bonner Boundary Clearwater Idaho Kootenai Latah Lewis Nez Perce Shoshone Ada Adams Boise Elmore Gem Owyhee Valley Washington - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Table 37--Sampling errors by Forest Survey Unit and county for area of timberland, volume, average annual net growth, average annual removals, (Sampling error in percent) 51.13 17.50 20.90 31.89 12.76 29.75 41.24 100.00 88.15 16.50 - - 91.39 51.15 60.63 70.78 100.00 21.66 100.00 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 55.47 21.04 23.55 36.36 13.40 34.61 48.37 100.00 91.82 19.40 - - 91.59 56.12 63.49 73.60 100.00 24.21 94.40 18.73 10.84 12.76 9.25 8.23 14.58 22.09 65.80 27.47 7.67 100.00 15.65 11.97 19.41 51.41 43.92 10.08 35.83 16.02 14.88 20.13 18.36 14.91 14.94 19.55 49.63 100.00 10.05 100.00 18.76 18.11 100.00 100.00 86.58 100.00 28.88 (Table 37 continued on next page) - - - - 8.33 18.27 - - - - 9.69 20.08 Total Total 3.96 6.51 5.88 34.93 6.12 2.95 4.61 2.49 1.56 5.63 7.45 34.07 17.86 2.23 100.00 6.32 4.78 7.96 43.58 12.08 2.18 26.12 6.58 2.95 5.09 2.49 4.65 6.13 7.45 34.07 17.86 2.23 100.00 6.95 5.09 9.05 43.58 19.72 5.33 26.12 16.90 9.37 10.85 8.14 7.47 13.47 20.14 62.00 23.23 6.84 100.00 14.88 10.79 18.02 50.36 36.41 8.92 31.86 16.94 13.22 23.24 16.95 22.40 15.82 19.58 50.36 90.88 10.92 100.00 24.74 19.80 100.00 100.00 97.07 74.90 35.02 1.05 2.22 1.68 3.26 3.52 5.87 6.54 89.46 Forest area Timberland area Volume Average annual net growth Average annual removals Average annual mortality Volume Average annual net growth Average annual removals Average annual mortality Growing stock Sawtimber Forest Survey Unit and county
126 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Appendix E: Soil Indicator Core Tables.

Table S1a: Mean water, carbon, and nitrogen contents of forest floor and soil cores by forest type, Idaho, soil visit

1, 2000, 2001, 2002, 2004, 2007, 2008.

Table S1b: Mean water, carbon, and nitrogen contents of forest floor and soil cores by forest type, Idaho, soil visit

2, 2006, 2007, 2009.

Table S2a: Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 1, 2000, 2001,

2002, 2004, 2007, 2008.

Table S2b: Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 2, 2006, 2007,

2009.

Table S3: Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 2, 2006, 2007, 2009.

Table S4: Mean exchangeable cation concentrations in soil cores by forest type, Idaho, soil visit 2, 2006, 2007,

2009.

Table S5a: Mean extractable trace element concentrations in soil cores by forest type, Idaho, soil visit 1, 2000,

2001, 2002, 2004, 2007, 2008.

Table S5b: Mean extractable trace element concentrations in soil cores by forest type, Idaho, soil visit 2, 2006,

2007, 2009.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 127

Table S1a—Mean water, carbon, and nitrogen contents of forest floor and soil cores by forest type, Idaho, soil visit 1, 2000, 2001, 2002, 2004, 

2007, 2008.

Forest type

Soil

layer

Number

of

plots

Water

contenta

Organic

carbon

Inorganic

carbon

Total

nitrogen

C/N

ratio

Forest

floor

massa

Organic

carbon

Total

nitrogen

cm % % % % Mg/ha Mg/ha Mg/ha

Cercocarpus woodland Forest 

floor 1

0–10 1 4.95 2.41 1.67 0.335 7.2 19.77 2.75

10–20 1 4.65 2.01 5.02 0.237 8.5 9.52 1.124

Juniper groupb Forest 

floor 5 3.64 31.09 0.624 67.2 1.01 0.29 0.006

0–10 5 3.7 2.08 0.21 0.162 12.8 16.74 1.303

10–20 5 6.77 0.95 0.18 0.103 9.3 8.31 0.898

Ponderosa pine Forest 

floor 17 28.81 30.56 0.891 34.6 24.5 6.62 0.207

0–10 17 16.44 2.71 0.17 0.128 21.3 21.12 0.994

10–20 17 11.95 1.54 0.16 0.094 16.4 13 0.794

Lodgepole pine Forest 

floor 16 39.98 31.93 0.869 41.3 13.94 4.23 0.117

0–10 16 15.99 2.82 0.18 0.124 22.8 19.07 0.836

10–20 16 10.69 1.61 0.16 0.065 24.6 13.02 0.53

Douglas fir Forest 

floor 70 22.89 31.27 0.868 38.5 18.32 5.34 0.149

0–10 70 7.62 3.23 0.18 0.15 21.5 19.57 0.91

10–20 70 8.6 1.93 0.18 0.095 20.4 13.21 0.647

Cottonwood/aspen Forest 

floor 11 29.79 35.49 1.073 34.6 13.9 4.44 0.143

0–10 11 18.77 5.87 0.19 0.421 14 25.08 1.798

10–20 11 17.23 3.34 0.19 0.231 14.4 19.2 1.33

Spruce/fir groupc Forest 

floor 51 42.29 30.89 0.907 35.5 23.81 6.88 0.206

0–10 51 18.34 4.75 0.17 0.218 21.8 26.26 1.203

10–20 51 18.18 2.67 0.16 0.137 19.6 18.12 0.925

Western hemlock/

redcedar/larch

Forest 

floor 14 53.97 26.02 0.706 38.3 39.1 9.68 0.259

0–10 14 17.7 4.27 0.21 0.211 20.2 19.5 0.964

10–20 14 14.41 1.87 0.18 0.104 17.9 12.16 0.678

Limber pine Forest 

floor 1 7.39 25.16 0.553 46.5 2.85 0.75 0.018

0–10 1 19.35 7.23 0.12 0.331 21.8 56.85 2.604

10–20 1 4.49 2.47 0.06 0.098 25.3 24.39 0.964

a

Water content and forest floor mass are reported on an oven-dry weight basis (105 oC).

b

Juniper group includes Rocky Mountain juniper, western juniper, and juniper woodland. 

c

Spruce/fir group includes Engelmann spruce, subalpine fir, mixed Engelmann spruce/subalpine fir, and grand fir.
128 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Table S1b—Mean water, carbon, and nitrogen contents of forest floor and soil cores by forest type, Idaho, soil visit 2, 2006, 2007, 2009.

Forest type

Soil

layer

Number

of

plots

Water

contenta

Organic

carbon

Inorganic

carbon

Total

nitrogen

C/N

ratio

Forest

floor

massa

Organic

carbon

Total

nitrogen

cm % % % % Mg/ha Mg/ha Mg/ha

Cercocarpus woodland Forest 

floor 1

0–10 1 1.05 2.67 5.18 0.287 9.3 13.06 1.403

10–20 1

Juniper groupb Forest 

floor 1 20.5 38.27 0.989 47 3.22 1.25 0.042

0–10 1 7.52 2.65 0.33 0.211 12.5 18.84 1.502

10–20 1 14.51 1.71 0.36 0.139 12.3 15.82 1.282

Ponderosa pine Forest 

floor 5 21.23 32.38 0.975 35.7 30.81 9.84 0.313

0–10 5 12.96 2.89 0.28 0.182 15.9 24.32 1.531

10–20 5 12.85 1.52 0.23 0.111 13.7 14.75 1.08

Lodgepole pine Forest 

floor 4 102.79 33.56 0.854 38.9 32.28 10.57 0.254

0–10 4 16.39 3.47 0.33 0.112 31 22.72 0.732

10–20 4 9.82 1.18 0.34 0.043 27.9 8.08 0.29

Douglas fir Forest 

floor 23 28.56 33.15 1.044 33.5 18.8 6.41 0.194

0–10 23 13.8 3.34 0.28 0.169 19.8 20.9 1.056

10–20 23 9.28 1.34 0.27 0.077 17.5 8.43 0.483

Cottonwood/aspen Forest 

floor 5 40.35 34.79 1.08 34.3 12.51 4.32 0.134

0–10 5 47.17 7.76 0.27 0.413 18.8 36.79 1.959

10–20 5 43.25 3.93 0.34 0.219 18 14.31 0.797

Spruce/fir groupc Forest 

floor 15 46.94 36.07 1.072 37.4 17.46 6.08 0.178

0–10 15 28.47 4.45 0.29 0.224 19.9 24.69 1.241

10–20 15 26.65 2.73 0.25 0.153 17.9 17.45 0.976

Western hemlock/

redcedar/larch

Forest 

floor 5 53.84 29.84 0.923 36.3 46.83 14.46 0.394

0–10 5 23.94 4.35 0.21 0.207 21 22.05 1.051

10–20 5 27.48 2.08 0.23 0.108 19.3 11.4 0.59

Limber pine Forest 

floor 0

0–10 0

10–20 0

a

Water content and forest floor mass are reported on an oven-dry weight basis (105  ̊C).

b

Juniper group includes Rocky Mountain juniper, western juniper, and juniper woodland. 

c

Spruce/fir group includes Engelmann spruce, subalpine fir, mixed Engelmann spruce/subalpine fir, and grand fir.
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 129

Table S2a—Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 1, 2000, 2001, 2002, 2004, 2007, 

2008.

Forest type

Soil

layer

Number

of

plots SQIa

Bulk

density

Coarse

fragments pH

Bray 1

extractable

phosphorus

Olsen

extractable

phosphorus

cm % g/cm3 % H2O CaCl2 mg/kg mg/kg

Cercocarpus woodland 0–10 1 56 1.49 44.86 8.03 0.59 8.1 4.8

10–20 1 52 1.41 66.53 7.94 0.53 0.1 2.6

Juniper group 0–10 5 71 1.12 27.25 6.21 0.26 17 12.7

10–20 5 65 1.35 34.87 6.17 0.31 4.4 1

Ponderosa pine 0–10 17 69 0.97 18.81 5.94 0.15 40.4 22.7

10–20 17 65 1.17 26.53 6.01 0.13 25.9 11.7

Lodgepole pine 0–10 16 62 0.97 28.59 5.45 0.16 37.9 19.3

10–20 16 59 1.25 32.89 5.49 0.15 30.2 15.1

Douglas fir 0–10 70 70 0.96 34.73 6.04 0.08 56.5 31.7

10–20 70 64 1.14 36.93 6.01 0.08 35.4 16.6

Cottonwood/aspen 0–10 11 74 0.76 35.82 6.33 0.2 112.6 46.5

10–20 11 72 0.99 36.41 6.36 0.17 19.6 33.1

Spruce/fir group 0–10 51 67 0.8 28.25 5.28 0.09 32 15.4

10–20 51 59 0.95 25.77 5.5 0.08 18 9.4

Western hemlock/

redcedar/larch 0–10 14 67 0.76 35.48 5.94 0.16 25.9 13.8

10–20 14 61 1.02 30 6.09 0.15 19 12

Limber pine 0–10 1 74 1.05 25.29 5.69 0.59 55.4 25.4

10–20 1 56 1.98 50.26 5.77 0.53 31.2 15.8

a

SQI = Soil Quality Index
130 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Table S2b—Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 2, 2006, 2007, 2009.

Forest type

Soil

layer

Number

of

plots SQIa

Bulk

density

Coarse

fragments pH

Bray 1

extractable

phosphorus

Olsen

extractable

phosphorus

cm % g/cm3 % H2O CaCl2 mg/kg mg/kg

Cercocarpus woodland 0–10 1 52 1.54 68.17 7.78 0.61 7.5 8.2

10–20 1

Juniper group 0–10 1 70 1.27 43.82 6.72 0.61 25.7 7.5

10–20 1 70 1.24 25.21 7.02 0.47 8.6 0.9

Ponderosa pine 0–10 5 74 1.03 17.71 5.99 0.27 73 38.6

10–20 5 71 1.18 16.86 6.23 0.21 45.3 24.5

Lodgepole pine 0–10 4 53 0.84 21.94 5.25 0.31 23.7 10.6

10–20 4 46 1.36 46.87 5.29 0.23 17.8 6.1

Douglas fir 0–10 23 70 0.97 33 6.04 0.14 45.6 26.3

10–20 23 63 1.21 42.74 6 0.11 34.8 19.9

Cottonwood/aspen 0–10 5 74 0.59 19.94 6.19 0.31 48.9 35.5

10–20 5 67 0.77 48.85 6.29 0.27 11.7 40.4

Spruce/fir group 0–10 15 69 0.77 25.21 5.66 0.19 39.9 24.3

10–20 15 67 0.96 31.46 5.81 0.15 28.3 16.1

Western hemlock/

redcedar/larch 0–10 5 68 0.85 31.32 5.74 0.27 25.1 11.5

10–20 5 61 0.85 29.41 5.81 0.21 5.2 8

Limber pine 0–10 0

10–20 0

a

SQI = Soil Quality Index
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 131

Table S3—Mean physical and chemical properties of soil cores by forest type, Idaho, soil visit 2, 2006, 

2007, 2009.

Forest type

Soil

layer

Number

of plots

1 M NH4Cl Exchangeable cations

Na K Mg Ca Al ECEC

cm mg/kg cmolc/kg

Cercocarpus woodland 0–10 1 22 413 168 6742 0 36.18

10–20 1 30 93 127 5199 0 27.36

Juniper group 0–10 5 22 252 213 1907 1 12.24

10–20 5 28 337 394 2235 3 15.56

Ponderosa pine 0–10 17 9 295 142 1486 32 9.97

10–20 17 11 208 102 1141 13 7.7

Lodgepole pine 0–10 16 17 179 54 570 68 5.29

10–20 16 16 145 31 450 46 3.96

Douglas fir 0–10 70 12 248 123 1569 15 10.03

10–20 70 12 205 92 1128 20 7.61

Cottonwood/aspen 0–10 11 18 373 159 1960 6 12.74

10–20 11 13 432 181 1839 7 12.58

Spruce/fir group 0–10 51 14 160 90 909 80 8

10–20 51 12 119 51 488 77 5.16

Western hemlock/

redcedar/larch 0–10 14 8 161 96 1509 111 10.47

10–20 14 17 145 59 894 15 5.8

Limber pine 0–10 1 30 109 193 2512 5 14.59

10–20 1 1 65 105 1319 3 7.64
132 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Table S4—Mean exchangeable cation concentrations in soil cores by forest type, Idaho, soil visit 2, 2006, 2007, 2009.

Forest type

Soil

layer

Number

of plots

1 M NH4Cl Exchangeable cations

Na K Mg Ca Al ECEC

cm mg/kg cmolc/kg

Cercocarpus woodland 0–10 1 6 455 140 6327 1 33.93

10–20 1

Juniper group 0–10 1 15 317 319 2547 0 16.21

10–20 1 9 645 457 3740 5 24.16

Ponderosa pine 0–10 5 25 453 218 1911 1 13.01

10–20 5 64 396 208 1657 2 11.48

Lodgepole pine 0–10 4 8 125 22 171 75 2.5

10–20 4 12 98 15 79 59 1.66

Douglas fir 0–10 23 32 333 151 1896 9 12.17

10–20 23 32 231 110 1213 13 8.37

Cottonwood/aspen 0–10 5 65 219 218 3132 0 20.03

10–20 5 47 144 166 1874 4 12.74

Spruce/fir group 0–10 15 63 197 90 1267 46 9.19

10–20 15 82 158 64 887 23 7.12

Western hemlock/

redcedar/larch 0–10 5 52 148 83 1071 51 8.22

10–20 5 49 126 54 599 37 5.3

Limber pine 0–10 0

10–20 0
USDA Forest Service Resour. Bull. RMRS-RB-14. 2012 133

Table S5a—Mean extractable trace element concentrations in soil cores by forest type, Idaho, soil visit 1, 2000, 2001, 2002, 

2004, 2007, 2008.

Forest type

Soil

layer

Number

of plots

1 M NH4Cl Extractable

Mn Fe Ni Cu Zn Cd Pb S

cm mg/kg

Cercocarpus woodland 0–10 1 0.03 0 0 0 0 0 0.47 7.5

10–20 1 0 0 0 0 0 0.02 0 10.3

Juniper group 0–10 5 13.22 0.05 0 0 0.42 0.11 0.1 5.5

10–20 5 11.32 0 0.07 0.11 0 0.01 0.02 8.1

Ponderosa pine 0–10 17 25.99 0 0.15 0 1.94 0.06 0.11 5.3

10–20 17 19.89 0.38 0.19 0.02 0.78 0.05 0.08 10.4

Lodgepole pine 0–10 16 22.43 0.76 0 0 0.69 0.11 0.09 4.9

10–20 16 22.43 0.57 0.02 0.03 0.26 0.08 0.25 17.8

Douglas fir 0–10 70 23.89 0.38 0.03 0 0.42 0.07 0.09 5.5

10–20 70 15.63 0.1 0.01 0 0.05 0.05 0.15 10.1

Cottonwood/aspen 0–10 11 9.63 0.78 0.06 0 0.18 0.18 0.1 5.9

10–20 11 9.41 0.02 0.03 0.05 0.02 0.12 0.11 6.6

Spruce/fir group 0–10 51 34.63 4.71 0.24 0.02 1.14 0.15 0.36 4.7

10–20 51 21.67 1.07 0.02 0.03 0.45 0.07 0.21 8.6

Western hemlock/

redcedar/larch 0–10 14 27.5 0.01 0.03 0 0.73 0.06 0.06 5.4

10–20 14 12.75 0 0.02 0.01 0.24 0.05 0.15 29.5

Limber pine 0–10 1 20.85 0 0 0 0.67 0.08 0 5.2

10–20 1 10.62 0 0 0 0.25 0 0.11 0
134 USDA Forest Service Resour. Bull. RMRS-RB-14. 2012

Table S5b—Mean extractable trace element concentrations in soil cores by forest type, Idaho, soil visit 2, 2006, 2007, 2009.

Forest type

Soil

layer

Number

of plots

1 M NH4Cl Extractable

Mn Fe Ni Cu Zn Cd Pb S

cm mg/kg

Cercocarpus woodland 0–10 1 0.34 0 0 0 0.01 0 6.1

10–20 1

Juniper group 0–10 1 5.57 0 0 0 0.06 0.67 4.1

10–20 1 2.02 0 0 0 0.05 0 3.7

Ponderosa pine 0–10 5 16.08 0.54 0 0.37 0.05 0.23 4

10–20 5 9.41 0.08 0 0 0.03 0.07 1.6

Lodgepole pine 0–10 4 27.24 4.52 0.04 0.07 0.04 0.34 4.1

10–20 4 4.19 2.97 0.01 0 0.01 0.52 4.8

Douglas fir 0–10 23 19.46 0.19 0.01 0.16 0.08 0.1 3.8

10–20 23 8.6 0.41 0.02 0.02 0.05 0.3 2.3

Cottonwood/aspen 0–10 5 11.48 0.72 0 0 0.07 0.16 71.5

10–20 5 4.93 0 0.01 0 0.01 0.19 53.2

Spruce/fir group 0–10 15 28.65 2.53 0 0.46 0.08 0.65 5.2

10–20 15 14.84 1.36 0 0.29 0.05 0.44 4.2

Western hemlock/

redcedar/larch 0–10 5 22.3 2.05 0 0.08 0.05 0.33 6.5

10–20 5 13.35 0.63 0 0 0.02 0.04 4.2

Limber pine 0–10 0

10–20 0
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Rocky

 Mountain

 Research Station

The Rocky Mountain Research Station develops scientific information 

and technology to improve management, protection, and use of the 

forests and rangelands. Research is designed to meet the needs of 

the National Forest managers, Federal and State agencies, public and 

private organizations, academic institutions, industry, and individuals. 

Studies accelerate solutions to problems involving ecosystems, range, 

forests, water, recreation, fire, resource inventory, land reclamation, 

community sustainability, forest engineering technology, multiple use 

economics, wildlife and fish habitat, and forest insects and diseases. 

Studies are conducted cooperatively, and applications may be found 

worldwide.

Station Headquarters

Rocky Mountain Research Station

240 W Prospect Road

Fort Collins, CO 80526

(970) 498-1100

Research Locations

Reno, Nevada

Albuquerque, New Mexico

Rapid City, South Dakota

Logan, Utah

Ogden, Utah

Provo, Utah

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its 

programs and activities on the basis of race, color, national origin, age, disability, 

and where applicable, sex, marital status, familial status, parental status, religion, 

sexual orientation, genetic information, political beliefs, reprisal, or because all 

or part of an individual’s income is derived from any public assistance program. 

(Not all prohibited bases apply to all programs.) Persons with disabilities who 

require alternative means for communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 

720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, 

Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, 

DC 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA 

is an equal opportunity provider and employer.

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