United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Resource Bulletin

RMRS-RB-11

December 2010

Colorado’s Forest 

Resources, 2002-2006

Michael T. Thompson, Joseph A. Duda, 

Larry T. DeBlander, John D. Shaw, Chris Witt, 

Todd A. Morgan, and Michael C. Amacher
Abstract _______________________________________________

Thompson, Michael T.; Duda, Joseph A.; DeBlander, Larry T.; Shaw, John D.; Witt, Chris; Morgan, Todd A.; 

Amacher, Michael C. 2010. Colorado’s forest resources, 2002-2006. Resour. Bull. RMRS-RB-11. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 108 p.

This report presents a summary of the most recent inventory information for Colorado’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 Colorado’s forest 

land totals 23 million acres. Nearly 50 percent of this forest land is administered by the USDA Forest Service. 

Pinyon-juniper forests cover over 5.5 million acres whereas forest comprised of fir, spruce, and hemlock comprise 

24 percent of Colorado’s forest land. Aspen is the single most abundant tree species in Colorado. Net annual 

growth of all live trees 5.0 inches diameter and greater on Colorado forest land totaled 219.6 million cubic feet. 

Average annual mortality totaled nearly 421.0 million cubic feet. 

The Authors __________________

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 (contact: 

mtthompson@fs.fed.us, 801-625-5374).

Joseph A. Duda is the Forest Management Division 

Supervisor of the Colorado State Forest Service. He 

holds a B.S. degree in forestry from Michigan Technical 

University.

Larry T. DeBlander 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 Forest 

Science from Pennsylvania State University.

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 

You may order additional copies of this publication by sending your 

mailing information in label form through one of the following media. 

Please specify the publication title and number.

Telephone (970) 498-1392

FAX (970) 498-1122

E-mail rschneider@fs.fed.us

Web site http://www.fs.fed.us/rmrs

Mailing Address Publications Distribution

Rocky Mountain Research Station

240 West Prospect Road

Fort Collins, CO 80526

Resources Management from the University of Alaska, 

Fairbanks and a Ph.D. in Forest Ecology from Utah State 

University.

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, UT. He holds B.S. and M.S. degrees in Ecology 

from Idaho 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.

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 The Pennsylvania State University.
Report Highlights ______________________________

Forest Area

• Colorado’s forest land area totals 23 million acres.

• Unreserved forest land accounts for most (88 percent) of the forest land in Colorado 

and totals 20 million acres.

• Fifty-seven percent of Colorado’s unreserved forest land is classified as timberland 

and 43 percent is classified as unproductive forest land.

• Nearly 50 percent of Colorado’s total forest land area, about 11.1 million acres, is 

administered by the USDA Forest Service.

• Pinyon-juniper forests cover over 5.5 million acres and account for 24 percent of 

forest land in Colorado.

• The fir-spruce-mountain hemlock forest type group totals nearly 4.7 million acres.

• Aspen forest types cover 3.1 million acres and are the third most abundant forest 

type group.

Numbers of Trees, Volume, and Biomass

• There are an estimated 12.7 billion live trees in Colorado.

• Softwood species total 6.3 billion trees or 49 percent of all live trees.

• Numbers of aspen trees total nearly 1.7 billion, making this species the single most 

abundant tree in Colorado.

• The net volume of live trees in Colorado on forest land totals 37.3 billion cubic feet.

• Growing-stock volume on timberland in Colorado totals 25 billion cubic feet, or 67 

percent of the total live volume on forest land.

• The total weight of oven-dry biomass on Colorado forest land is 676 million tons. 

• Net volume of sawtimber trees on timberland totals 92 billion board feet.

Acknowledgments _____________________________

The Rocky Mountain Research Station gratefully acknowledges the Colorado State 

Forest Service for its role in collecting the field data. The Rocky Mountain Research 

Station also gratefully acknowledges the cooperation and assistance of the Rocky 

Mountain Region, Forest Service, U.S. Department of Agriculture; the Bureaus of Land 

Management and Indian Affairs; and the National Park Service, U.S. Department of the 

Interior. The authors extend a special note of thanks to private landowners who provided 

information and access to field sample plots.

i
Forest Growth and Mortality

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

forest land totaled 219.6 million cubic feet.

• Average annual mortality totaled nearly 421.0 million cubic feet

• Mortality exceeded net growth for all major tree species except for aspen and 

western woodland softwoods.

Issues in Colorado’s Forest Resources

• Colorado is experiencing one of the largest outbreaks of mountain pine beetle 

in lodgepole pine forests since records became available for the State.

• As of 2006, the average annual biomass of insect-killed lodgepole pines is 926 

thousand dry tons, which represents a nearly threefold increase over the 331 

thousand dry tons recorded in 2002.

• Varied observers began noticing rapid mortality of aspen in multiple locations 

in southwestern Colorado beginning in 2004.

• Unlike bark-beetle caused mortality in lodgepole and ponderosa pine forests, 

trends in aspen mortality over the annual inventory period in Colorado do not 

indicate a significant upward trend since 2002. 

• It does not appear that the recently observed aspen mortality event is reflected 

in Colorado’s annual inventory, which could be due to (1) the event is relatively 

recent, (2) the event may be a localized event that impacts aspen in domains 

too small to be adequately assessed in a broad-scale inventory, (3) diverse 

factors associated with the decline make causal agents difficult to identify, and 

(4) aspen stand dynamics are complex.

Forest Health

• The high level of conifer mortality occurring in Colorado is currently of paramount 

concern.

• Examination of current mortality rates puts a perspective on what the impact 

might have on the inventory of live trees.

• Conifer mortality rates on National Forest lands, where 78 percent of the conifer 

mortality is occurring, average over 1.3 percent annually.

• True firs recorded the highest annual conifer mortality rate of 2.5 percent, followed by lodgepole pine at 1.4 percent.

• The high numbers of sapling-size conifers in relation to larger-size conifers 

indicates sustainable regeneration for the foreseeable future at the State level.

ii
Contents_____________________________________________

Page

Report Highlights .....................................................................................................................i

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

Colorado’s Forest Inventory ..................................................................................................1

Comparison with Previous Inventories..................................................................................1

Timber Products Output ........................................................................................................2

Inventory Methods...................................................................................................................3

Plot Configuration..................................................................................................................3

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

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

Sources of Error....................................................................................................................5

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

Overview of Colorado’s Forest Resources ...........................................................................7

Ecoregion Provinces of Colorado..........................................................................................7

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

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

Forest Type .........................................................................................................................10

Stand Age............................................................................................................................10

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

Numbers of Trees................................................................................................................17

Live Tree Volume, Biomass, and Sawtimber.......................................................................18

Forest Growth and Mortality................................................................................................20

Issues in Colorado’s Forest Resources ..............................................................................21

Mountain Pine Beetle..........................................................................................................21

Sudden Aspen Decline........................................................................................................28

Other Resources in Colorado’s Forests..............................................................................30

Invasive and Noxious Weeds..............................................................................................30

Snags as Wildlife Habitat ....................................................................................................32

Forest Soil Resources in Colorado .....................................................................................36

Removals for Timber Products ............................................................................................36

Backround...........................................................................................................................36

Findings...............................................................................................................................38

Interpretation.......................................................................................................................40

Forest Health..........................................................................................................................40

Conclusions...........................................................................................................................43

Standard Forest Inventory and Analysis Terminology ......................................................44

References .............................................................................................................................51

Appendix A: Common Name, Scientific Name, and Timber (T) or Woodland (W) 

Designation for Trees Measured in Colorado’s Annual Inventory ..........................53

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

Designation for Forest Type .......................................................................................54

Appendix C: Volume, Biomass, and Site Index Equation Sources...................................55

Appendix D: Appendix D Tables ..........................................................................................56

Appendix E: Appendix E Tables.........................................................................................100

iii

USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 1

Introduction_____________________________________________________

Colorado’s Forest Inventory

This resource bulletin highlights results of Colorado’s forest resources as interpreted 

from the first series of annual forest measurements in the State. Annual surveys of U.S. 

forests were mandated by the Agricultural Research Extension and Education Reform 

Act of 1998 (Farm Bill, http://thomas.loc.gov/cgi-bin/query/z?c105:s.1150.enr:). They 

feature (1) a nationally consistent, fixed-radius, four-point plot configuration; (2) a 

systematic national sampling design consisting of a national base grid where each plot 

represents approximately 6,000 acres; (3) integration of the forest inventory and forest 

health monitoring sampling designs; (4) annual measurement of a fixed proportion of 

permanent plots; (5) reporting of data or data summaries within 6 months after yearly 

sampling; (6) a default 5- to 10-year moving average estimator; and (7) a summary 

report every 5 years.

The Interior West Forest Inventory and Analysis (IWFIA) program and the Colorado 

State Forest Service (CSFS) began the forest inventory of Colorado’s forest resources in 

2002. CSFS field crews were responsible for collecting field data and IWFIA personnel 

were responsible for training CSFS field crews and assuring that measurement procedures 

were meeting national standards. This joint effort launched the new annual inventory 

system in which one-tenth of the field plots (considered one panel) are measured each 

year. In 2006, IWFIA completed measurement of the fifth panel of inventory plots 

in Colorado. This resource bulletin consolidates data from all five panels in the first 

cycle of annual measurements and uses that information to describe the current issues 

affecting the status and condition of the State’s forests. Past inventories of Colorado 

were referred to as periodic inventories where estimates were derived from measurements of all plots in the State over a period of 2 to 3 years. Two previous inventories 

of Colorado’s forest resources were completed in 1983 and 1959 (Benson and Green 

1987; Miller and Choate 1964).

Comparison with Previous Inventories

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 two inventories must be compatible. There are three significant 

factors that cause incompatibility between the 2006 annual inventory of Colorado and 

the previous periodic inventory completed in 1983 (Benson and Green 1987).

Colorado’s Forest Resources,

2002-2006

Michael T. Thompson

Joseph A. Duda

Larry T. DeBlander

John D. Shaw

Chris Witt

Todd A. Morgan

Michael C. Amacher
2 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Inventory procedures—The first factor is that inventory procedures varied by 

major ownership category in the previous inventory. In 1983, lands controlled by 

National Forest Systems (NFS) and Bureau of Land Management (BLM) were not 

inventoried by IWFIA. The forest inventory estimates such as forest area, volume, 

growth, and mortality were supplied to IWFIA by NFS and BLM. IWFIA only 

measured inventory plots on lands owned by State agencies and private individuals. 

The 1983 report merged this inventory data from the different sources to describe 

the status and condition of Colorado’s forest resources. In the 2006 annual inventory, forest resource data were collected by IWFIA and CSFS on all lands meeting 

the definition of forest land regardless of the species of trees present, ownership 

status, or administrative status of the land. This includes wilderness areas and 

other areas in reserved status. The 2006 inventory adhered to all national protocols 

such as plot configuration, field variables with nationally consistent meanings and 

measurements, and national precision standards. None of these national protocols 

were in place in 1983.

Definitions—The second factor is that many definitions of forest resource attributes 

have changed since 1983. 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.

Sampling intensity—The third factor is differences in sampling intensity. The 2006 

inventory contains five annual panels of data that represent approximately 50 percent 

of all inventory plots initially established in Colorado. Therefore, the reduced sample 

size in the moving average estimation process will result in a higher level of statistical 

uncertainty compared to a periodic inventory where all plots in the State were measured. This is an important consideration not only when comparing data from previous 

inventories but also when evaluating forest estimates for small domains. Examples of 

small domains are individual counties, small groups of counties, individual National 

Forests, or small ecological provinces.

The 2006 inventory of Colorado’s forests marks an important shift from its predecessors, both in the scope of its measurements and in its timeliness. With the resources to 

measure one 10-percent panel of the total sample locations each year, it is now possible 

and practical to monitor emerging resource issues by providing yearly “snapshot” updates 

and longer term trend analysis. The resulting improvements in timeliness, combined 

with the national effort to standardize national inventory procedures, have transformed 

Colorado’s forest inventory into a tool that can detect short-term trends, address relevant 

issues, examine ecological relationships, and evaluate human activities that will shape 

the forests of Colorado for the future.

Timber Products Output

Timber harvest estimates and the composition and operation of the primary forest 

products industry in Colorado are presented in this report. The major source of data for 

these studies was a census of primary forest products facilities in Colorado and adjacent 

States that received timber from Colorado during calendar year 2002. This information is the direct result of a cooperative effort between The University of Montana’s 

Bureau of Business and Economic Research (BBER) and the USDA Forest Service 

IWFIA program. Together, BBER and Forest Service research stations have been conducting periodic mill censuses in the Rocky Mountains for over 25 years. The Forest 

Industries Data Collection System (FIDACS) was developed by BBER and IWFIA to 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 3

collect, compile, and make available State- and county-level information on the operations of the forest products industry and the timber it uses. The FIDACS uses a written 

questionnaire or phone interview of forest products manufacturers to collect the following information for each facility for a given calendar year: production capacity and 

employment; volume of raw material received by county and ownership; species of 

timber received; finished product volumes, types, sales, values, and market locations; 

and utilization and marketing of manufacturing residue. Information collected through 

the FIDACS is processed, analyzed, and stored at the BBER in Missoula, Montana. 

Additional information is available by request; however, individual firm-level data are 

confidential and will not be released.

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 0 degrees, 120 degrees, and 

240 degrees from the center of the central subplot. Each standing tree with a diameter 

at breast height (d.b.h.) or diameter at root collar (d.r.c.) 5-inches or larger is measured 

on these subplots. Each subplot contains a 6.8-foot radius microplot with the center 

located 12 feet east of the subplot center on which each tree with a d.b.h./d.r.c. from 

1.0-inch to 4.9-inches is measured.

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

or setting 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. Field crews assign an arbitrary number to the first condition class encountered on a plot. This number 

is then defined by a series of predetermined 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.

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. 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 interpenetrating, nonoverlapping panels, each of which provides complete, systematic coverage of the State. Each 

year the plots in a single panel are measured, and panels are selected on either a 5-year 

(eastern regions) or 10-year (western regions) rotating basis (Reams and Van Deusen 

1999). For estimation purposes, the measurement of each panel of plots is considered 

an independent, equal probability sample of all lands in a State.
4 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Three-Phase Inventory

FIA conducts inventories in three phases, which are discussed in detail below. Phase 1 

uses remotely sensed data to obtain initial plot land cover observations and to stratify 

land area in the population of interest 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.

Phase 1—Remotely sensed data in the form of aerial photographs, digital orthoquads, 

and satellite imagery are used for initial plot establishment. Spatial analysts determine 

a digitized geographic location for each field plot, and a human interpreter determines 

whether a plot location has the potential to sample forest land. Plot locations with the 

potential to sample forest land and that are accessible to field crews are selected for 

further measurement by field crew visits in Phase 2.

The remote sensing medium used for stratification in Colorado was 2004 MODIS 

satellite imagery. The spatial resolution of the MODIS imagery used was 250 meters. 

Three strata were recognized: forest land, nonforest land, and census water. The spatial resolution of the imagery was 250 meters. Depending on geography and sampling 

intensity, areas are identified within a State for area computation and are referred to as 

estimation units. In Colorado, individual counties served as the estimation units. Each 

estimation unit’s area 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 Colorado is 

defined as:

A A ˆ n

n

y

n g Tg

hg

h g

H ihg

i

n

hg

hg

= ′

′ =

= ∑

∑

1

1

where:

Aˆ

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

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

H = number of strata

n′

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

n′

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 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 condition-level observations 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 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 5

crews record a variety of observations and measurements including species, live/dead 

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

Office staff use statistical models based on field crew measurements to calculate 

values for additional variables including individual tree volume and per unit area 

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

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

Phase 3 is administered cooperatively by the FIA program, other Forest Service programs, other Federal agencies, State natural resource agencies, and universities, and it 

is partially integrated with the Forest Health Monitoring (FHM) program. The ground 

survey portion of the FHM program was integrated into the FIA program as Phase 3 in 

1999. The Phase 3 sample consists of a 1:16 subset of the Phase 2 plots with 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.

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 2002-2006 FIA inventory of Colorado is based on a sample of 5,595 

plots systematically located across the State (a total area of 66.6 million acres), a sampling rate of approximately one plot for every 11,900 acres.

The statistical estimation procedures are described in detail in Bechtold and Patterson 

(2005) and provide the estimates of the population totals and means presented in this 

report. 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. A sampling error can be interpreted to mean that the chances are two out of 

three that had 100-percent inventory been taken using these methods, the results would 

have been within the limits indicated. The sampling errors for State-level 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:

SE SE

X

X s t

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 
6 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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 

(such as 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 

regular program of quality control and quality assurance is an integral part of all FIA 

data collection efforts. This program begins with the documentation of protocols and 

procedures used in the inventory followed by extensive crew training. To assess the 

quality of the data collected by these trained crews, a random sample of plots are measured independently by a different qualified crew—referred to as blind checks. The 

measurement on these blind check plots is done by a crew termed the QA crews. In all 

cases, QA crews have as much or more experience and training in FIA field measurements as the standard FIA crews.

The quality of field measurements is assessed nationally through a set of measurement quality objectives (MQO’s) that are set for every data item FIA collects. Each 

MQO consists of two parts: a tolerance or acceptable level of measurement error, and 

an objective interval of the percent of measurements within tolerance. The blind check 

measurements are used to observe how often individual field crews are meeting these 

objectives and to assess the overall compliance among all crews. QA results for the 

Colorado inventory are illustrated in tables E6 and E7.

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

models) to provide observations of the 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. Models are used to 

predict volume and biomass estimates of individual tree volumes.

Overview of Tables_______________________________________________

Forest Inventory and Analysis is currently working on a revised National Core Table 

set that will expand the suite of tabled 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 Colorado annual data for the years 2002 through 2006. 

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. Inventory cycle (cycle 2) is a number assigned to a 

set of plots measured over a particular period of time from which a state estimate using 

all possible plots is obtained. Additional tables that supplement specific sections are 

in Appendix E and are numbered consecutively as they appear, starting with table E1.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 7

Overview of Colorado’s Forest Resources___________________________

Ecoregion Provinces of Colorado

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 boundary-less 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.

Colorado is at the confluence of seven ecoprovinces (Bailey 1995): (1) the Colorado Plateau Semi-Desert Province in the southwestern part of the State, (2) the Great 

Plains-Palouse Dry Steppe Province encompasses most of the eastern part of the State, 

(3) the Intermountain Semi-Desert Province in the northern part, (4) the Intermountain 

Semi-Desert and Desert Province in the west, (5) the Nevada-Utah Mountains-SemiDesert Province in the northwest, (6) the Southern Rocky Mountain Steppe Province in 

the central and western part of the State, and (7) the Arizona-New Mexico Mountains 

Semi-Desert that occupies a very small portion in the southern region of Colorado.

The most prominent ecoprovince is the Southern Rocky Mountain Steppe, which 

contains the most forested area and greatest variety of forest types. This region is home 

to the Rocky Mountains, rugged glaciated mountains as high as 14,000 feet. Forests in 

this province are characterized by vegetational zonation, controlled by a combination 

of altitude, latitude, direction of prevailing winds, and slope exposure. The uppermost 

vegetational 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. Fire disturbance regimes create stands of aspen or lodgepole pine in the 

subalpine and montane zones. Below the montane belt is the foothill zone. Dry rocky 

slopes abound in this province, and ponderosa pine and pinyon-juniper are the typical 

forest types found, depending on slope exposure.

The Great Plains-Palouse Dry Steppe Province is characterized by rolling plains 

and tablelands of moderate relief in a broad belt that slopes gradually eastward from an 

altitude of 5,500 ft (1,520 m) near the foot of the Rocky Mountains. This region, often 

referred to as the Great Plains grasslands, has scattered trees, shrubs, and supports many 

species of grass. Forests are nearly nonexistent in this province.

The remaining four ecoregion provinces are characterized by dry rocky foothills, 

mesas, and plateaus. The predominate forest types in these regions are pinyon pine, juniper, or a mix of both commonly referred to as pinyon-juniper woodlands. The forests 

in these semi-desert regions are commonly associated with sagebrush communities.

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-11. 2010

Unreserved forest land is further divided into timberland and unproductive forests. 

Timberland is 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 Standard Forest Inventory and Analysis Terminology).

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 (see the “Standard 

Forest Inventory and Analysis Terminology” section).

The State of Colorado encompasses nearly 67 million acres of land area, of which 

23 million acres were estimated by FIA as forest land. Forest land, which FIA generally defines as land with 10 percent or more live tree cover (see Standard Forest 

Inventory and Analysis Terminology), is primarily located in the central and western 

regions of Colorado (fig. 1). Unreserved forest land accounts for most (88 percent) of 

the forest land in Colorado and totals 20 million acres (table 2). Fifty-seven percent of 

Figure 1—MODIS imagery depicting lands with 10 percent or more tree cover 

in Colorado, 2002-2006.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 9

Colorado’s unreserved forest land is classified as timberland and 43 percent is classified 

as unproductive forest land. Reserved forests account for only 12 percent, or 2.6 million acres, of total forest land and most of this area is classified as productive reserved.

Forest Land Ownership

Nearly 50 percent of Colorado’s total forest land area, about 11.1 million acres, is 

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

land in Colorado consists of 10 different National Forests and two National Grasslands. 

Nearly all of National Forest System’s forest land is on land controlled by National 

Forests with a very small amount occurring on land controlled by National Grasslands. 

Almost 82 percent of National Forest System’s forest land is classified as unreserved 

forest land. About 7.8 million acres, or 71 percent, of National Forest System’s forest 

land is classified as timberland (table 2).

The other major agency that controls a significant amount of forest land in Colorado 

is the Bureau of Land Management (BLM). Forest land administered by the BLM totals 4.8 million acres. Most of BLM’s forest land—about 95 percent—is classified as 

unreserved. Only 15 percent of BLM’s forest land meets the conditions to qualify as 

timberland.

Privately owned forest land totals 5.4 million acres. Private landowners are a diverse 

group in Colorado consisting of private individuals and corporations. All private forest 

land is in the unreserved owner class and this area is evenly split between the timberland 

and unproductive category (table 2).

The remaining amount of forest land in Colorado is controlled by the National Park 

Service (NPS), State and local government, and the Department of Defense. Over 723 

thousand acres are controlled by State and local governments, another 339 thousand 

acres are controlled by the NPS, and 112 thousand acres are controlled by the Department of Defense.

Figure 2— Area of forest land by owner group, Colorado, 2002-2006.
10 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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.

The most abundant forest type group in Colorado is the pinyon-juniper group (fig. 3). 

Pinyon- juniper forests cover over 5.5 million acres and account for 24 percent of forest 

land in the State (table 3). Second in abundance, the fir-spruce-mountain hemlock forest 

type group totals nearly 4.7 million acres. This type group is comprised of subalpine fir, 

white fir, Engelmann spruce, and Colorado blue spruce. Engelmann spruce accounts for 

the majority (over 62 percent) of the forest area classified in the fir-spruce-mountain 

hemlock type group. Aspen forest types cover 3.1 million acres and are the third most 

abundant forest type group. The gambel oak forest type totals another 2.6 million acres. 

Lodgepole pine forest types comprise 2.1 million acres or 9 percent of forest area in 

Colorado. Ponderosa pine and Douglas-fir each account for 1.7 million acres

Stand Age

The present age structure of Colorado’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 predominated with 

small-diameter trees are very difficult to accurately assign a stand age to. All nonstocked 

forest conditions—those forested areas that have less than 10 percent stocking of live 

trees because of disturbance—are assigned a stand age of unclassified.

Most of the forest land in Colorado is between 60 and 120 years of age (table 6). 

Over 43 percent, or almost 10 million acres, of the forest land is between 60 and 120 

years of age. About 12 percent of the forest land is in stands under 21 years of age and 

less than 6 percent are over 200 years of age.

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

type groups in the State (fig. 4). Pinyon-juniper forests are the oldest type group with 

over half of the forest area in stands over 140 years old. Sixteen percent of pinyonjuniper stands are over 200 years old. Aspen, which is generally shorter lived than most 

Colorado conifer species, is characterized by a larger number of stands in the younger 

age classes with over 72 percent of aspen forests in stands 61 to 120 years old and over 

10 percent in stands less than 21 years old. Sixty-five percent of the fir-spruce-mountain 

hemlock type group area is concentrated in stands between 80 and 160 years of age. 

Of all the major softwood forest types in Colorado, lodgepole pine displays the most 

even-aged distribution. About 69 percent of lodgepole pine stands are between 60 and 

120 years old.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 11

Figure 3—FIA plot locations depicting four major forest types in Colorado overlayed on MODIS imagery depicting lands 

with 4 classes of tree cover in Colorado, 2002-2006. Plot locations have been altered using a procedure defined as fuzzing 

and swapping.

Aspen 3.1 million acres

(continued)
12 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Pinyon-Juniper 5.5 million acres

Figure 3—(Continued).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 13

Lodgepole pine 2.1 million acres

Figure 3—(Continued).
14 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Fir-spruce-mountain hemlock 4.7 million acres

Figure 3—(Continued).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 15

Stand Density Index (SDI)

Stand density index (Reineke 1933) is a relative measure of stand density, based on 

quadratic mean diameter of the stand and the number of trees per acre. In the western 

States, silviculturists often use SDI as one measure of stand structure to meet diverse 

objectives such as ecological restoration and wildlife habitat (e.g., 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 

(USDA Forest Service 1991). Maximum SDI is rarely, if ever, observed in nature at the 

stand scale because the onset of competition-induced (self-thinning) mortality occurs 

at about 60 percent of the maximum SDI. 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 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).

Figure 4—Distribution of forest land by stand age class and forest type group in Colorado, 2002-2006.
16 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Originally developed for even-aged stands, SDI can also be applied to uneven aged 

stands (Long and Daniel 1990; Shaw 2000). Stand structure can influence the computation of SDI, so the definition of maximum SDI must be compatible with the computation method. 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 

preparation). The revised maximum SDIs, which are compatible with FIA computation 

methods, are shown in table E1. 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 Colorado is relatively balanced. Stands appear 

to be well-stocked, with over 60 percent of forest acres fully occupied (fig. 5). This 

distribution is likely to skew toward lower-density stands in the coming years, because 

the most recent data suggests that there has been considerable mortality in conifers. 

The data in this report reflect some of the drought-related mortality of common pinyon 

that started in 2003 (Shaw and others 2005), but there has been a dramatic increase in 

mortality in other conifer species in Colorado (see more information about conifer and 

aspen mortality in the “Forest Health” section of this report).

With time, low-density stands should increase in relative density due to growth of 

the residual trees. Whether or not there will be additional in-filling by regeneration will 

depend on a number of factors, including the timing of seed crops and favorable climatic 

conditions. These trends should be captured by future plot measurements.

Figure 5—Distribution of stand density on forest land, Colorado, 2002-2006.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 17

Numbers of Trees

A measure of the numbers 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 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 12.7 billion live trees in Colorado (table 10). Softwood species 

total 6.3 billion trees or 49 percent of the total (fig. 6). Over 54 percent of softwood trees 

are under 5.0 inches in diameter and nearly 6 percent are 15.0 inches and larger in diameter. The Engelmann and other spruce species group, comprised of Engelmann spruce 

and Colorado blue spruce, is the most abundant softwood species group accounting for 

24 percent, or 1.5 billion trees, of the softwood total. Next in abundance is the true fir 

species group at 1.4 billion trees. The true fir species group is comprised of subalpine fir, 

white fir, and corkbark fir. Third in abundance is the western woodland softwood species 

group at 1.3 billion trees. The western woodland softwood species group is comprised 

of common pinyon, Utah juniper, Rocky Mountain juniper, and oneseed juniper. At 1.1 

million trees, lodgepole pine is the fourth most abundant softwood.

Figure 6—Number of live trees on forest land by species group and diameter class, Colorado, 2002-2006.
18 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

The western woodland hardwood species group accounts for the majority (74 percent) 

of the hardwood species occurring in Colorado. This species group is primarily gambel 

oak, a small, deciduous tree with a shrub-like growth form. The small-diameter characteristic is reflected in the size-class distribution of this species in figure 6. Nearly 98 

percent of all western woodlan hardwoods stems are less than 5.0-inches in diameter.

Quaking aspen is a very important tree in Colorado. Stands of aspen are esthetically 

appealing and provide excellent habitat for a wide variety of wildlife. Numbers of 

aspen trees total nearly 1.7 billion making this species the single most abundant tree 

in Colorado. Most of the aspen trees are concentrated in the smaller diameter classes. 

Thirty-eight percent of all live aspen stems are in the 2-inch class and 49 percent are 

between 3 and 9 inches in diameter.

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 Colorado on forest land totals 37.3 billion cubic feet 

(table 12). Seventy-one percent, or 26.4 billion cubic feet, is located on lands controlled 

by National Forest System lands. Fourteen percent, or 5.3 billion cubic feet, is under 

private ownership. Thirteen percent, or 4.8 billion cubic feet is on lands controlled by 

various federal agencies not classified as National Forest System. The remainder, about 

0.8 billion cubic feet, is on lands controlled by State and local government. The total 

weight of oven-dry biomass on Colorado forest land is 676 million tons.

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 at culmination of mean annual increment. 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 

“Standard Forest Inventory and Analysis Terminology” section). 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 Colorado totals 25 billion cubic feet, or 67 percent of the total live 

volume on forest land (fig. 7). Net volume of sawtimber trees on timberland totals 92 

billion board feet (table 19).

Engelmann and blue spruce together account for the majority (28) percent of growingstock volume on timberland (fig. 8). Second in abundance, aspen totals 4.7 billion cubic 

feet of growing-stock volume. Growing-stock volume of lodgepole pine total 4.5 billion 

cubic feet and ranks third. The true fir species group ranks fourth at 3.3 billion cubic 

feet. Engelmann and blue spruce also account for the majority of sawtimber volume 

(32.5 billion board feet).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 19

Figure 7—Volume of live trees on forest land by ownership status, productivity, and merchantability status, Colorado, 

2002-2006.

Figure 8—Volume of growing-stock trees on timberland by species group, Colorado, 2002-2006.

0 

5 

10 

15 

20 

25 

30 

35 

40 

Total all live volume Live volume on unreserved 

forest land 

Live volume on timberland Growing-stock volume on 

timberland 

Live volume (billion cubic feet) 
20 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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 Colorado 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 points in 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 helps to quantify the change in inventory volume over time. Net growth minus mortality approximates the average annual 

change in inventory volume not including the average annual volume removed through 

timber harvesting (removals).

Net annual growth of all live trees 5.0 inches diameter and greater on Colorado forest land totaled 219.5 million cubic feet while mortality totaled nearly 421.0 million 

cubic feet (tables 22 and 25). Figure 9 illustrates the relationship between net growth 

and mortality by species group in Colorado. Mortality exceeded net growth for all major tree species except for aspen. The most striking relationship between growth and 

removals occurred in the true fir species group where annual mortality exceeded net 

growth by over thirteen-fold. Annual mortality of lodgepole pine was nearly five times 

net growth; mortality exceeded net growth by 11 percent for the Engelmann and other 

spruce species group. Aspen had the most positive relationship between net growth and 

mortality of any major species group in Colorado. Net annual growth of aspen exceeded 

annual mortality by 40 percent.

Figure 9—Net annual growth and mortality of live trees on forest land by species group, Colorado, 2002-2006.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 21

Issues in Colorado’s Forest Resources_ _____________________________

Mountain Pine Beetle

The USDA Forest Service Region 2 Forest Health Management (FHM) Group 

began statewide aerial surveys of mountain pine beetle infestations in 1996. This 

monitoring effort has recorded significant increases in the area of lodgepole pine 

forests affected by the mountain pine beetle since 1996 and, as of 2007; the epidemic 

is believed to be catastrophic and unprecedented. Figure 10 illustrates a cartographic 

product produced by the FHM management center depicting the increase in area of 

lodgepole pine forests affected by the mountain pine beetle since 2002. 

The epidemic, which has caused widespread mortality of lodgepole pines in Colorado, 

may eventually alter the look of the landscape and presents a risk to local economies that 

depend on mountain tourism. Fire hazards, falling tree hazards, and threats to watersheds 

are some of the safety issues that have forest managers concerned.

Figure 10—Epidemic spread of lodgepole pine tree mortality between 2000 

and 2009 caused by mountain pine beetle in Colorado. Areas of heavy 

mortality are shaded red. These maps were created using digital coverage’s 

downloaded from Forest Health Protection’s Aerial Detection Dataset (USDA 

Forest Service, Forest Health and its Partners). The damaged areas were 

identified through aerial sketchmapping, which is a remote sensing technique 

that is independent of the FIA annual sample data. Land that has a minimum 

of 10 percent crown cover is shaded in green. More information about the 

Aerial Detection Dataset, aerial sketchmapping, and limitations associated 

with aerial survey data can be found at http://www.fs.fed.us/r2/resources/

fhm/aerialsurvey/download/.
22 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Figure 10—(Continued).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 23

Figure 10—(Continued).
24 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Figure 10—(Continued).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 25

Figure 10—(Continued).
26 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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 (Caroll and others 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). 

Because of the recent interest in climate change, 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 11 illustrates the average annual biomass of lodgepole and ponderosa pine trees 

killed by insects by measurement year. The assumption is that most of the lodgepole 

and ponderosa pines 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 5 years of annual inventories in Colorado. As of 2006, the average annual biomass of insect-killed lodgepole pines is 926 thousand dry tons, which 

represents a nearly threefold increase over the 331 thousand dry tons recorded in 2002. 

Damage, and type of damage, is also recorded for all live trees 5.0 inches and larger 

on FIA plots. Figure 12 indicates the percentage of live lodgepole pines damaged by 

bark beetles by measurement year. The increase in percentage of lodgepole pine trees 

damaged by bark beetles reflects the increase in insect-killed trees. This percentage 

increased from 0.89 percent in 2002 to a high of 3.7 percent in 2006.

Figure 10—(Continued).
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 27

0

100

200

300

400

500

600

700

800

900

1000

2002 2002-03 2002-04 2002-05 2002-06

T

housand

dry tons

Measurement years

0

0.5

1

1.5

2

2.5

3

3.5

4

2002 2002-03 2002-04 2002-05 2002-06

Perce

nt

Measurement years

Figure 11—Moving average estimate of average annual aboveground dry weight of lodgepole and ponderosa 

pine trees killed by insects by measurement years, Colorado, 2002-2006. 

Figure 12—Moving average estimate of percentage of live lodgepole pines damaged by bark beetles by 

measurement years, Colorado, 2002-2006.
28 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Sudden Aspen Decline

Quaking aspen is the most abundant and important hardwood species in Colorado. Aspen 

is a valuable ecological component of Colorado’s landscape, occurring in pure forests as 

well as growing in association with many conifer species. In addition to the tree’s desirable 

scenic value, the diversity of understory plants that occur under the aspen canopy supplies 

critical wildlife habitat, valuable grazing resources, and protection for soil and water.

Varied observers began noticing rapid mortality of aspen in multiple locales in southwestern Colorado beginning in 2004 (Worrel and others 2008). The difference between 

this recently observed aspen mortality and the typical mortality observed in aspen stands 

is the suddenness of the phenomenon and the apparent lack of regeneration occurring in 

stands where the overstory mortality is unusually high. Evidence to date suggests that 

it is a decline disease incited by acute, warm drought. Predisposing factors include low 

elevation, south and southwest aspects, droughty soils, open stands, and physiological 

maturity. The agents that actually kill the stressed trees include Cytospora canker, two 

bark beetle species, poplar borer, and bronze poplar borer.

How serious is the observed mortality of aspen? Unlike mountain pine beetle infestations, an event that has been extensively researched, there is no recorded precedent 

for this phenomenon. The aspen mortality appears to be a function of several agents 

acting singly or in combination. Aspen forests are dynamic and have always changed 

in response to climate, frequency and intensity of disturbance, and natural succession. 

No conclusive evidence to date indicates whether this event will continue or what the 

eventual impact on the aspen resource will be.

Figure 13 illustrates the average annual biomass of aspen trees classified as mortality by measurement year. All causes of death were included in this illustration. Unlike 

bark-beetle caused mortality in lodgepole and ponderosa pine forests, trends in aspen 

mortality over the annual inventory period in Colorado do not indicate a significant 

upward trend since 2002.

Aspen ecologists have also expressed concern about the level of aspen regeneration 

occurring in affected stands. In many of these stands, aspen sprouting is weak and the 

rootstock is in poor condition. For an aspen stand to successfully reestablish itself after 

a disturbance, sprouting must be abundant and vigorous to offset losses to ungulate 

browsing, diseases, and insects. Otherwise, other vegetative types may overwhelm the 

aspen component and the aspen clone will eventually die.

Is aspen successfully regenerating in Colorado? There are several ways that aspen 

regeneration can be evaluated using FIA data. Although aspen often grows in pure 

stands, the species also grows with a large number of other species such as Douglasfir and lodgepole pine. Therefore, only analyzing plot data where forest conditions 

were classified as an aspen forest type eliminates many stands where aspen is present. 

Figure 14 illustrates the mean number of aspen trees on forest conditions defined as an 

aspen site. An aspen site is any forest condition where at least one live aspen (including 

seedlings), one standing dead aspen, or one aspen classified as mortality was recorded. 

The assumption is that these sites currently have or had the capability to support aspen. 

The number of live aspen seedlings on aspen sites average 690 stems per acre. Small 

diameter trees (1.0-4.9 inches d.b.h.) average 156 trees per acre, medium diameter trees 

(5.0-11.9 inches d.b.h.) average 79 trees per acre, large diameter trees (12.0 inches and 

larger) average 9 trees per acre, and aspen snags (standing dead trees 5.0 inches d.b.h. 

and larger) average 16 trees per acre. These mean numbers of aspen trees suggest that, 

overall, aspen stands have a distribution of trees sizes that do not indicate a significant 

deficiency in regeneration.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 29

0

200

400

600

800

1000

1200

1400

2002 2002-03 2002-04 2002-05 2002-06

T

housand

dry tons

Measurement years

Figure 13— Moving average estimate of average annual aboveground dry weight of aspen trees classified as mortality 

by measurement years, Colorado, 2002-2006.

Figure 14—Mean number of live aspen trees per acre on aspen sites by tree size class, Colorado, 2002-2006.

0

100

200

300

400

500

600

700

800

900

Seedlings Small diameter Medium diameter Large diameter Standing dead trees

N

u

m

bers of trees per acre Error bars represent 95% confidence interval Tree-size class
30 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

It does not appear that the recently observed aspen mortality event is reflected in 

Colorado’s annual inventory. There are several reasons for this (Thompson 2009a). First, 

the rapid mortality associated with the phenomenon is relatively recent—it was first 

observed by researchers in 2004 (Worrel and others 2008). Second, it may be more of 

a localized event that will impact aspen in domains too small to be adequately captured 

in a broad-scale inventory. Third, the diverse factors associated with the decline make 

it difficult to assess cause of death and damaging agents that have been associated with 

the perceived decline. Fourth, aspen stands dynamics are complex. It is a relatively 

short-lived species susceptible to a host of pathological organisms. Aspen primarily 

regenerates through development of new shoots from the root systems of mature trees 

and successful regeneration depends on temperature, soil conditions, moisture, and age 

of parent trees.

Other Resources in Colorado’s Forests______________________________

Invasive and Noxious Weeds

Noxious plant species can have many negative effects on forest communities. Invasive 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 on a 

plot that contains a forested condition. This allows for the spatial and temporal extent 

of these species to be documented as plots are revisited.

A total of 2,213 sample conditions were used to assess the occurrence of noxious 

plant species in Colorado. These samples represent plots that had a forested condition 

recorded somewhere within the boundaries of the four subplots. Thirty-three different 

weed species were documented on forested plots in Colorado, with one or more found 

on 384 (17.4%) of the sampled conditions. Cheatgrass (Bromus tectorum) and Canada 

thistle (Cirsium arvence) were the most common weeds species found. These two 

species accounted for just under 60 percent of the weed occurrences (fig. 15). Canada 

thistle was the most ubiquitous species, being detected on all forest-type groups other 

than Other Western Hardwoods.

The Elm-Ash-Cottonwood forest-type group has the highest infestation rate of at 

least one weed species, followed by the Nonstocked and the Ponderosa Pine groups 

respectively (fig. 16). Some of the forest-type groups have small sample sizes so results 

for these groups should be interpreted with caution. The Nonstocked group had the highest diversity of noxious species with eighteen, followed by the Aspen-Birch, Ponderosa 

Pine and Western Oaks groups which each had fourteen species (fig 16).

It appears that younger stands are more susceptible to infestation than are older stands. 

The sampled conditions that had stand-ages of less than 100 years were almost twice 

as likely to have noxious weeds found in them (fig. 17).

Colorado’s forests appear to be susceptible to infestation of noxious species to varying 

degrees. While cheatgrass and Canada thistle were found in almost every type of forest, 

other species were more specialized or otherwise restricted to a handful of groups. The 

hardwoods tend to have a higher infestation frequency and a wider diversity of noxious 

species than the softwood groups, although the Ponderosa Pine group was an exception 

to this general trend.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 31

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

Elm-Ash-Cottonwood

Nonstocked

Ponderosa Pine

Western Oak

Other Western Hardwoods

Pinyon-Juniper

Aspen-Birch

Douglas-fir

Spruce-Fir-Mountain Hemlock

Lodgepole Pine

Other Western Softwoods

Figure 15—Frequency count of numbers of forested conditions with at least one noxious weed species present, Colorado, 

2002-2006.

Figure 16—Percentage of plots infected with noxious weed species by forest-type group, Colorado, 2002-2006.

0

20

40

60

80

100

120

140

N

u

m

ber of forested conditions

Noxious plant species

Jointed goatgrass

Whitetop

Meadow knapweed

Oriental virginsbower

Field bindweed

Fuller’s teasel

Russian olive

Broomleaf toadflax

Bouncingbet

Field sowthistle

Hoe nightshade

Hardheads

Spotted knapweed

Diffuse knapweed

Oxeye daisy

Scotch cottonthistle

Caraway

Poison hemlock

Koshia

Dalmatian toadflax

Saltcedar

Yellow star-thistle

Leafy spurge

Butter and eggs

Gypsyflower

Burdock

Bull thistle

Nodding plumeless thistle

Sulphur cinquefoil

Spiny plumeless thistle

Common mullein

Canada thistle

Cheatgrass
32 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Figure 17—Percentage of forest conditions infected with noxious weed species by stand age, Colorado, 2002-2006.

0.00%

5.00%

10.00%

15.00%

20.00%

25.00%

<=100 >100

Perce

nt of plots infected

Stand age (years)

Many nonstocked stands have recently been disturbed by fire, harvest, disease, or 

other perturbations that have removed much if not all of vegetative cover. These plots 

are more susceptible to invasion because noxious species can compete with native pioneer species for resources that were unavailable when the stand was stocked and had 

an established understory community. Understory communities are also still developing 

in young stands, leaving space and resources available for noxious species to utilize. 

More mature stands often reach a point of relative stability with native species using 

available space and resources.

Snags as Wildlife Habitat

Standing dead trees (snags) provide important habitat in the forested ecosystems of 

Colorado. There are countless organisms that utilize snags at some point in their life 

history. These include, but are not limited to, bacteria, fungi, insects, rodents, cavitynesting birds, bats, raptors, mustelids, and black bear. The height and diameter of standing dead trees are important variables to species that consider the utility of 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 and quality of individual snags that 

meet criteria important to wildlife.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 33

Many of the species within the guild of cavity-nesting birds found in Colorado utilize 

snags that are greater than 9 inches d.b.h.. They also tend to choose trees 34 feet or taller 

when available. Silver-haired bats (Lasionycteris noctivagans) have been associated with 

trees 12 inches or greater d.b.h. and taller than 25 feet. Although black bears (Ursus 

americanus) do not require snags for den sites, pregnant females and those with cubs 

select them over ground dens where they are available. Bears prefer snags 30 inches 

or greater d.b.h. and taller than 16 feet. Examples below illustrate how FIA variables 

that record the d.b.h., actual height, live or dead status, and lean code can be used to 

quantify potential den, nest, and roost sites for black bears, cavity-nesting birds, and 

silver-haired bats.

There are almost 140 million snags in Colorado that meet the size preferences of most 

cavity nesting birds found in the State. Silver-haired bats have an estimated 74 million 

snags that have the potential to be suitable roost sites (fig. 18). There are roughly 766,000 

trees that have the potential for black bear den sites in Colorado (fig. 19).

Available snags for cavity-nesting birds are predominately found in fir/spruce/mountain 

hemlock, aspen/birch and lodgepole pine forest type groups, but several other groups 

contribute potential habitat. These are the same forest types that hold the majority of 

snags preferred by silver-haired bats. However, the suite of forest type groups that have 

black bear den site potential is much smaller. Many snags usable as black bear den sites 

are found in the pinyon-juniper, fir-spruce-mountain hemlock and aspen/birch forest 

type groups.

0

10

20

30

40

50

60

70

Fir/Spruce/Mtn. 

Hemlock

Lodgepole Pine Nonstocked Western Oak Pinyon-Juniper

N

u

mbers of sn

ags (milli

o

ns)

Forest-type group

Cavity-nesting birds

Silver-haired bats

Black bear

Figure 18—Number of snags that meet the size preferences of most cavity nesting birds and suitable roost sites for 

silver-haired bats by forest-type group, Colorado, 2002-2006.
34 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Engelmann spruce contributes the most snags for all species combined, with subalpine 

fir, lodgepole pine and aspen being available in abundance for both bats and cavitynesting birds (fig. 20). Engelmann spruce, Utah juniper and Douglas-fir provide the 

bulk of the potential den sites for black bear (fig. 21).

Aspen, Engelmann spruce, lodgepole pine, and subalpine fir are valuable tree species 

for several forest birds and mammals, even when found in other forest types (mixed 

stands). Depending on where they are located on the landscape, pinyon-juniper snags 

can be used by black bears. 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 water are important to silver-haired 

bats. Proximity to hard mast resources (juniper berries and acorns in Colorado), slope, 

aspect, presence of a cavity and the amount and timing of snow-pack are important in 

determining the relative value of trees as den sites for black bears. FIA data can address 

many of these factors and there are current efforts to build predictive models for these 

species in Colorado by using data collected by our crews. These models can be valuable 

tools for Federal and State land managers, as roughly 90 percent of the suitable snags 

measured by FIA occur on public lands.

0

100000

200000

300000

400000

500000

600000

Fir-Spruce-Mountain Hemlock Aspen-Birch Pinyon-Juniper

N

u

mbers of sn

a

gs

Forest type group

Figure 19—Number of snags that have the potential for black bear den sites by forest-type group, Colorado, 2002-2006.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 35

0 5 10 15 20 25 30 35 40

Engelmann spruce

Subalpine fir

Lodgepole pine

Aspen

Douglas-fir

Ponderosa pine

White fir

Corkbark fir

Limber pine

Common pinyon

Narrowleaf cottonwood

Bristlecone pine

Southwestern white pine

Fremont cottonwood

Colorado Blue spruce

Utah juniper

Number of snags (millions)

Silver-haired bats

Cavity-nesting birds

0

50

100

150

200

250

300

350

Engelmann spruce Utah juniper Douglas-fir White fir Subalpine fir

N

u

mber of snags (thousan

ds)

Forest type group

Figure 20—Number of snags 

that meet the size preferences 

of most cavity nesting birds and 

suitable roost sites for silverhaired bats by snag species 

group, Colorado, 2002-2006.

Figure 21—Number of snags that have the potential for black bear den sites by snag species group, Colorado, 2002-2006.
36 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Forest Soil Resources in Colorado

Soils on the landscape are the product of five interacting soil forming factors: 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 Colorado organized by forest type is in the Soil Indicator core 

tables (tables E2, E3a, E3b, and E3c) in Appendix E. Some of the key soil properties 

were graphed by forest type group in Colorado, and to place these results in a regional 

context, these graphs are placed side by side with graphs of regional results.

With the exception of western oaks and western softwoods in Colorado, soil carbon and 

nitrogen percentages generally increased from drier to wetter forest environments in 

both Colorado and the Interior West region (fig. 22). Generally, soil moisture increases with 

elevation and latitude (cooler temperatures) and forest types reflect this climatic gradient. 

When expressed in terms of megagrams of carbon or nitrogen per hectare of forest 

area, carbon stocks also generally increase with elevation and latitude (fig. 23), with 

the exception of western oaks and western softwoods. Soil nitrogen stocks show a more 

mixed response to climatic gradients in Colorado and the Interior West.

Aspen forests store more N in the mineral soil than any other forest group in the 

Interior West (fig. 23, right side). In Colorado, both western oaks and aspen store the 

most soil nitrogen (fig. 23, left side). Aspen forests store significantly more nitrogen 

than spruce/fir forests, which often intermingle with aspen. High nitrogen levels in aspen 

forest floor and soils leads to lower carbon/nitrogen ratios than those found in forest 

floor and soils under spruce/fir (fig. 22). Since low carbon/nitrogen is a good indicator 

of relative organic matter decomposition rate, nutrient-rich aspen leaves decompose 

quickly and easily compared to spruce/fir needles.

Soil pH generally decreases with increasing elevation, latitude, and precipitation 

(fig. 24). The more acidic soils are found in the wetter high-elevation forest types. This 

is also reflected in higher levels of exchangeable Al in wetter high-elevation forest 

soils (fig. 24). In both Colorado and the Interior West as a whole, much higher levels 

of aluminum are found in spruce/fir than aspen soils. Aspen are intolerant of high levels of exchangeable aluminum. In the Interior West as a whole, aspen soils store more 

potassium than other forest type groups (fig. 24). In Colorado, western oaks, Douglas 

fir, aspen, and some western softwoods forests store comparable amounts of soil potassium. High levels of exchangeable calcium are found in the calcareous, high-pH soils 

under western hardwoods including oaks and pinyon/juniper group woodlands (fig. 24).

Removals for Timber Products_ ___________________________________

Background

Volume removed from forest inventory during the harvesting of timber is known as 

removals. Removals are an important indicator of the sustainability of timber harvest. 

Removals that exceed growth could indicate over-harvesting and decreasing forest 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 37

Figure 22—Forest floor and 0-20 cm mineral soil % C, % N, and C/N arranged by forest type groups in Colorado (left side) and 

in five Interior West States (Arizona, Colorado, Idaho, Montana, and Utah) (right side). The forest type groups are arranged left to 

right in order of increasing latitude, elevation, and precipitation with some overlap among forest types.

inventory (standing volume), while growth greatly exceeding removals could signal 

a need for increased vegetation management to decrease risks of tree mortality, insect 

outbreaks, or wildfire.

Removals can come from two sources: the growing-stock portion of live trees (live 

trees meeting specified standards of quality or vigor), or dead trees and other nongrowing stock sources. The two general types of removals are timber products harvested 

for processing by mills and logging residue (i.e., volume cut or killed but not utilized). 

Removals, as reported here, are based on a 2002 survey of Colorado’s primary forest 

products industry (Morgan and others 2006).
38 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Figure 23—Soil organic carbon (top) and total nitrogen (bottom) stocks (Mg/ha) in the forest floor and 0-10 and 10-20 cm soil 

layers arranged by forest type groups in Colorado (left side) and in five Interior West States (Arizona, Colorado, Idaho, Montana, 

and Utah) (right side).

Findings

Colorado’s 2002 timber harvest for industrial wood products (excluding fuelwood) 

was approximately 79.7 million board feet (MMBF) Scribner, about 15 million cubic 

feet (MMCF). Dead trees accounted for about 20 MMBF (26 percent). The 2002 harvest was 23 percent lower than the 1982 harvest (McLain 1985) and 28 percent lower 

than the 1999 harvest (Lynch and Mackes 2001). Timber harvest volume in Colorado 

is estimated to have declined by more than 5 percent since 2002. The 2007 harvest was 

about 75.8 MMBF Scribner, and the 2008 harvest is estimated to be lower than 2007.

Removals for total timber products (including fuelwood) totaled 34.9 MMCF during 

2002 (table E4). Growing stock accounted for 11.8 MMCF (34 percent) of removals 

for products, with the remainder coming from other sources, including dead trees and 

other non-growing stock sources. Fuelwood, including residential firewood, was the 

leading product harvested, accounting for 54 percent of removals for products. Sawlogs 

accounted for 35 percent; logs chipped or shaved for composite products and excelsior 

accounted for 5 percent; and logs for miscellaneous products (e.g., log homes and log 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 39

furniture) accounted for 4 percent. Logs for posts, poles, and pilings accounted for the 

remaining 1 percent of removals for timber products. Approximately 78 percent (27.3 

MMCF) of removals for products consisted of softwood species. The largest volume 

of hardwoods was used for fuelwood, with smaller quantities chipped or shaved for 

composite products/excelsior and used for sawlogs.

Total removals from Colorado’s timberlands during 2002 were 38.6 MMCF (table 

E5). This included the 34.9 MMCF used for timber products and 3.6 MMCF of logging 

residue left in the forest as slash. Growing-stock removals were 12.5 MMCF. Slightly 

under 95 percent (11.9 MMCF) of growing-stock removals were used to produce wood 

products, and just over 5 percent (0.7 MMCF) were left in the forest as slash and not 

used. Sawlogs were the largest component (73 percent) of growing-stock removals, 

followed by logs chipped or shaved for composite products and excelsior (15 percent).

About 57 percent (7.1 MMCF) of growing-stock removals came from private and 

Tribal timberlands, while 38 percent (4.8 MMCF) came from national forests. Nearly 

5 percent of the volume removed from growing stock was from other public lands.

Figure 24—Soil pH and exchangeable potassium, calcium, and aluminum in the 0-20 cm soil layers arranged by forest type groups 

in Colorado (left side) and in five Interior West States (Arizona, Colorado, Idaho, Montana, and Utah) (right side).
40 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Ponderosa pine was the leading species harvested, accounting for 25 percent (3.1 

MMCF) of growing-stock removals. Aspen also represented about 25 percent, and spruce 

represented 23 percent. Lodgepole pine accounted for about 16 percent of growing-stock 

removals. Douglas-fir, true firs, and hardwoods other than aspen accounted for almost 

12 percent of growing-stock removals. Ponderosa pine was the leading species harvested 

for most products, accounting for 39 percent of growing-stock volume harvested for 

products other than sawlogs and composite products. Ponderosa pine accounted for 28 

percent of sawlog volume. Spruce was the leading species harvested for sawlogs. Aspen 

was the only species harvested for composite products and excelsior.

Interpretation

Sustainability of Colorado’s forests depends on sustainable harvest levels, a forest 

products industry capable of utilizing harvested material, and active management of the 

land base available for timber production. But Colorado’s annual timber harvest volume 

has generally been declining since the late 1980s, and the State’s forest products industry 

has been facing mill closures and curtailments for two decades as a result of reduced 

harvests, particularly from Federal lands. The severe downturn in the U.S. housing market 

since 2005, corresponding drops in lumber prices, and the current economic recession 

have further exacerbated the industry’s situation. However, the on-going mountain pine 

beetle epidemic may prove to be more challenging to forest sustainability, as the decline 

in Colorado’s forest products industry continues to erode the ability to actively manage 

forests and generate income for landowners to use towards activities like hazardous fuel 

reduction or forest restoration, which may not generate revenue. To ensure sustainable 

harvest levels for future generations, careful consideration should be given not only to 

growth, removals, and mortality across Colorado’s available timberlands, but also to the 

industry infrastructure that conducts management activities and uses harvested timber.

Forest Health_____________________________________________________

Forest managers, researchers, and the public have considerable concern over forest 

conditions in Colorado. The current mountain pine beetle epidemic in lodgepole pine 

forests has had a devastating visual impact in a State where recreation plays an important 

role in the economy. Elevated levels of mortality in spruce, fir, and pinyon pine forests 

have also been reported. What is the reason behind the high mortality rates? Declining forest health linked to climate change is one concern. Others speculate that several 

decades of fire suppression coupled with reduced levels of timber harvest on public 

lands have left a legacy of old, dense stands that are subject to potentially catastrophic 

wildfires, insect epidemics, and disease. Still others argue that periodic episodes of 

large-scale disturbances are expected occurrences and are natural ways for forests to 

regulate themselves.

How healthy or unhealthy are Colorado’s forests? To answer this question, one must 

define ‘forest health.’ Forest conditions are complex and seldom permanent. Forests go 

through many stages as they become established, change through the growth and aging 

process, or are dramatically affected by a disturbance such as a mountain pine beetle 

epidemic. Depending on one’s viewpoint, a disturbance event may be part of the natural 

dynamics within a healthy forest or it may be a sign that something is terribly wrong.

Colorado’s forests, like many western forests, are expected to produce a sustainable 

mix of values such as recreation, timber production, and healthy water supplies. Most 

definitions of forest health contain terms relating to sustainability. Diversity, complexity, 

ecosystem condition, and providing for human needs are additional criteria often used 

to describe forest health. One traditional measure of forest sustainability is the relationship between the components of forest change (net growth, mortality, and removals) 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 41

and the change in tree inventory over time. Because of the inconsistencies between the 

1980s inventory and the current annual inventory, a thorough assessment of the change 

in tree inventory over time is not possible. The absence of a paired plot re-measurement 

procedure limits the analysis of forest change but it is still possible to draw assumptions 

from the current ‘point in time’ approach to estimating net growth and mortality (see 

“Forest Growth and Mortality” section).

The high level of conifer mortality occurring in Colorado is currently of paramount 

concern. The short and long term consequences of this mortality event are difficult to 

assess. However, examination of current mortality rates can provide a benchmark for 

future impacts on the inventory of live trees. Mortality rates are simply the average 

annual mortality estimate divided by the inventory estimate of live trees. The current 

annual rate of conifer mortality averages 1.2 percent. The conifer mortality rates vary 

by ownership (fig. 25). Conifer mortality rates on National Forest lands, where 78 

percent of the conifer mortality is occurring, average over 1.3 percent annually. Mortality rates on private lands, where 9 percent of the conifer mortality is occurring, 

average 0.8 percent annually. Conifer mortality rates also vary by conifer species 

group. True firs recorded the highest annual conifer mortality rate of 2.5 percent, followed by lodgepole pine at 1.4 percent. The ponderosa and Jeffery pine species group 

recorded the third highest mortality rate of 1.3 percent. Annual mortality rates for the 

Douglas-fir, Engelmann and other spruces, and the western woodland softwood species 

groups average 1.0, 0.8, and 0.6 percent respectively.

What are the implications of these conifer mortality rates and what do they mean for 

forest health? Figure 26 illustrates the relationship between average annual mortality 

0

5000

10000

15000

20000

25000

Forest Service Other federal State and local

government

Undifferentiated

private

Million cubic feet

Ownership group

Annual Mortality

Live Volume

Figure 25—Volume and average annual mortality volume of live trees by ownership class, Colorado, 2002-2006.
42 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

and the estimate of live conifer inventory. The current conifer mortality rate will have 

to remain at the same level for many years or increase dramatically before the inventory 

of live conifers will be significantly affected. Comparing the annual conifer mortality 

rate of 1.2 percent to the annual conifer net annual growth rate of 0.45 percent indicates conifer inventories have been declining for several years but the decline ignores 

seedling and sapling size trees eventually growing into the larger diameter classes and 

contributing to inventory and growth estimates. Smaller trees generally have a lower 

susceptibility to mortality from disease and insects. Examination of the density-diameter 

relationship of smaller-size trees provides insight to the status of conifer regeneration. 

Forests with sustainable regeneration are found to have a reversed J-shaped size class 

distribution (West and others 1981). All of the conifer stand types in Colorado demonstrate 

this distribution (table 10, fig. 6). Numbers of live conifer trees in the 2-inch diameter 

class comprise nearly 35 percent of all live conifers. Numbers of live 2-inch trees in the 

true fir species group comprise 50 percent of all live true firs—the highest proportion 

of the major conifer species groups. In contrast, lodgepole pine registered the lowest 

proportion (25 percent) of trees in the smallest diameter class. However, the numbers 

of live lodgepole pines in the 2- and 4-inch class combined comprise 50 percent of all 

live lodgepole pines. The high numbers of sapling-size conifers relative to larger trees 

indicates sustainable conifer regeneration for the foreseeable future.

Will conifer mortality rates continue to increase? This question has generated considerable discussion with no conclusive answer. The warming of the climate and associated stresses are considered a factor in the high levels of mortality but additional 

research is needed into climate, natural disturbance cycles, and the mechanisms of tree 

Figure 26—Volume and average annual mortality volume of live trees by species group, Colorado, 2002-2006.

0

2000

4000

6000

8000

10000

12000

Douglas-fir Ponderosa and

Jeffery Pines

True fir Engelmann and

other spruces

Lodgepole

pine

Western

woodland

softwoods

Other western

softwoods

Million cubic feet

Conifer species group

Annual Mortality

Live Volume
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 43

mortality. Tree mortality can be a very complicated event. The exact cause of death can 

be difficult to determine due to the complex interaction of environmental stresses, disease, and insects. Most models of mortality are probabilities with significant variation. 

Should the mortality continue to increase the only thing that is certain is a reduction 

in average tree size. Stands affected by mortality will hold less carbon and old forest 

structures will decline in number. The exact impact on changes in forest composition 

and structure are uncertain.

Conclusions______________________________________________________

Colorado’s 23 million acres of forest land are one of the more complex ecosystems 

of the Interior West, with a diverse mix of coniferous and deciduous tree species. The 

major forest type groups in Colorado are the spruce-fir, pinyon-juniper, aspen, western 

oak, lodgepole pine, Douglas-fir, and ponderosa pine types. Also comprising significant 

areas of forest land are gambel oak, bristlecone pine, and Colorado blue spruce. The 

reason for this diversity is a physical landscape that ranges from flat plains and high 

plateaus to steep mountains and deep canyons. Within this landscape, a wide range of 

topographic, soil, and moisture regimes exist.

Most of Colorado’s forests are controlled by public agencies. Nearly half of all 

forest land is controlled by National Forest Systems and 24 percent is controlled by 

private landowners. The significant amount of public land points to a forest resource 

that must meet the diverse needs of people. These needs include shelter for people and 

wildlife, water quality, recreation, pollution control, and timber products that furnish 

jobs and strengthen local economies. The population of Colorado has been growing at 

a tremendous rate since 1990 in many of the mountain counties (Forstall 1995). This 

‘mountain sprawl’ has placed many homeowners in very close proximity to forest land. 

Naturally, people living in these settings are going to be concerned about anything that 

might endanger these forests and their homes, such as wildfire, insects, and disease.

The mountain pine beetle epidemic in Colorado is considered to be catastrophic and 

unprecedented. Forest managers have serious concerns about the future of lodgepole 

pine, the primary affected species. Temporal trend analysis of conifer mortality in 

Colorado has indicated significant increases in mortality of lodgepole pine and other 

conifer species through 2007 (Thompson 2009b). Whether the high level of mortality 

will continue into the future and what the eventual impact will be on the conifer resource 

in Colorado are topics for debate. The recent aspen mortality event does not appear to 

be reflected in the annual inventory estimates. Over time, as more years of annual data 

become available, aspen mortality can be evaluated with more confidence.

The information presented in this report points to opportunities for further analysis, 

investigation, and studies. The systematic interpenetrating panel design of the annual 

inventory presents opportunities to assess trends in inventory estimates never before 

possible with periodic inventories. Quantitative inferences about temporal trends require consideration of independent estimates of the population status each year, each 

of which uses completely different sample plots from different panels. Various timeseries model-based estimation techniques are currently being explored (Czaplewski and 

Thompson 2009). These model-based estimators can not only be used to track mortality 

events, they can lead to better monitoring of forest growth, live tree inventory, and tree 

harvest activity. Once the annual inventory effort extends into the second measurement 

cycle in Colorado, the power to detect significant effects related to tree mortality and 

other parameters of interest will increase substantially with estimates derived from the 

re-measured (paired) plots that will be available. What is clear is the need for accurate, 

consistent, long-term monitoring procedures for managers and researchers to study 

relationships between forest attributes and changing climate patterns. 
44 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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. 

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 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 45

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. 

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—A circular sample plot of a specified horizontal radius: 1/300 acre 

= 6.8-foot radius (microplot); 1/24 acre = 24.0-foot radius (subplot). 

Forest industry land—Land owned by a company or an individual(s) operating a 

primary wood-processing plant.

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. 
46 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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.

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. 
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 47

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. 

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. 
48 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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).

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 as timber-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.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 49

Sawtimber volume—The growing-stock volume in the saw-log portion of sawtimbersize trees in board feet.

Seedlings—Live trees less than 1.0 inch d.b.h./d.r.c.

Site index—A measure of forest 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 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. 
50 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

• Sapling/seedling stand—A stand at least 10 percent stocked with live trees, in 

which half or more of the total stocking is from live trees less than 5.0 inches 

in diameter. 

• Nonstocked stand—A formerly stocked stand that currently has less than 10 

percent stocking, but has the potential to again become 10 percent stocked. 

For example, recently harvested, burned, or windthrow-damaged areas. 

Stockability (Stockability factor)—An estimate of the stocking potential of a given 

site; for example, a stockability factor of 0.8 for a given site indicates that the site 

is capable of supporting only about 80 percent of “normal” stocking as indicated by 

yield tables. Stockability factors (maximum site value of 1.0) are assigned to sites 

based on habitat type/plant associations. 

Stocking—An expression of the extent to which growing space is effectively utilized 

by live trees. 

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).

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.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 51

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USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 53

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

Woodland (W) Designation for Trees Measured in Colorado’s Annual

Inventory_ ______________________________________________________

Aspen (Populus tremuloides) T

Blue spruce (Picea pungens) T

Boxelder (Acer negundo) W

Bristlecone pine (Pinus aristata) W

Common or twoneedle pinyon (Pinus edulis) W

Curlleaf mountain-mahogany (Cercocarpus ledifolius) W

Douglas-fir (Pseudotsuga menziesii) T

Eastern cottonwood (Populus deltoides) T

Engelmann spruce (Picea engelmannii) T

Fremont cottonwood (Populus fremontii) T

Gambel oak (Quercus gambelii) W

Limber pine (Pinus flexilis) T

Lodgepole pine (Pinus contorta) T 

Narrowleaf cottonwood (Populus angustifolia) T

Oneseed juniper (Juniperus monosperma) W

Plains cottonwood (Populus sargentii) T

Ponderosa pine (Pinus ponderosa) T

Rocky Mountain juniper (Juniperus scopulorum) W 

Southwestern white pine (Pinus strobiformus) W

Subalpine fir (Abies lasiocarpa) T

Utah juniper (Juniperus osteosperma) W

White fir (Abies concolor) T
54 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

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

or Woodland (W) Designation for Forest Type_______________________

Aspen-birch group

Aspen T

Douglas-fir group

Douglas-fir T

Elm-ash-cottonwood group

Cottonwood T

Fir-spruce-mountain hemlock group

Blue spruce T

Engelmann spruce T

Engelmann spruce-subalpine fir T

Subalpine fir T

White fir T

Lodgepole pine group

Lodgepole pine T 

Nonstocked

Nonstocked (only as stand-size class) T or W

Other western hardwoods group

Cercocarpus woodland (Mountain mahogany) W

Intermountain maple woodland (Maple woodland) W

Other western softwoods group

Foxtail pine-bristlecone pine T

Limber pine T

Pinyon-juniper group

Juniper woodland W

Pinyon-juniper woodland W

Rocky Mountain juniper W 

Ponderosa pine group

Ponderosa pine T

Western oak group

Deciduous oak woodland W
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 55

Appendix C: Volume, Biomass, and Site Index Equation Sources_______

Volume

Chojnacky (1985) was used for bigtooth maple, curlleaf mountain-mahogany, gamble 

oak, and singleleaf pinyon pine volume estimation.

Chojnacky (1994) was used for common or twoneedle pinyon pine, Rocky Mountain 

juniper, and Utah juniper volume estimation.

Edminster and others (1980) was used for ponderosa pine volume estimation in northeastern Utah.

Edminister and others (1982) was used for aspen volume estimation in northeastern Utah.

Hann and Bare (1978) was used for aspen, blue spruce, Douglas-fir, Engelmann spruce, 

Great Basin bristlecone pine, limber pine, lodgepole pine, ponderosa pine, subalpine 

fir, and white fir volume estimation in southwestern Utah.

Kemp (1956) was used for Fremont and narrowleaf cottonwood volume estimation.

Myers (1964) was used for limber and lodgepole pine volume estimation in northeastern 

Utah.

Myers and Edminister (1972) was used for blue spruce, Douglas-fir, Engelmann spruce, 

subalpine fir, and white fir volume estimation in northeastern Utah.

Biomass

Chojnacky (1984) was used for curlleaf mountain mahogany biomass estimation.

Chojnacky (1992) was used for bigtooth maple and gamble oak biomass estimation.

Chojnacky and Moisen (1993) was used for all juniper and pinyon species biomass 

estimation.

Van Hooser and Chojnacky (1983) was used for all timber (T) species biomass estimation.

Site Index

Brickell (1970) was used for blue spruce, Douglas-fir, Engelmann spruce, Great Basin 

bristlecone pine, limber pine, lodgepole pine, ponderosa pine, and subalpine fir 

site index estimation.

Edminster and others (1985) was used for aspen, and Fremont and narrowleaf cottonwood 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.]
56 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Appendix D: Appendix D 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 disturbed 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 standsize 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 (International 1⁄

4 inch rule) of sawtimber trees 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.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 57

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 29—Aboveground dry weight of all live trees by owner class and forest land status.

Table 30—Aboveground dry weight 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, county for area of timberland, volume, average annual growth, and average annual removals on timberland.
58 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Accessible forest land

Unreserved forest land

Unproductive

Reserved forest land

Nonforest and other land

Water

Nonsampled land

Table 1--Percentage of area by land status, Colorado, cycle 2, 2002-

2006.

Total area (thousands of acres)

Timberland 16.1

 12.0

Total unreserved forest land 28.1

Productive 3.1

Total reserved forest land 3.7

Nonforest and other-wooded land 64.1

Non-Census 0.2

Access denied 2.8

All land

 66,620

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 0.0

Hazardous conditions 0.9

All nonforest and other land 64.5

Census 0.3

All accessible forest land 31.8

Unproductive 0.6
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 59 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked 5,535.6 - - - - 24.4 87.2 35.0 3.2 242.9 2,573.4 41.4 427.0 Table 3--Area of accessible forest land by forest type group and productivity class, Colorado, cycle 2, 2002-2006. (In thousand acres) - - 1,563.5 1,574.9 2,172.8 1,726.8 196.7 133.8 1,708.5 - - - - 281.2 - - 190.6 90.0 2,101.5 250.1 - - 34.1 1,067.7 - - - - 55.9 - - - - - - 377.8 - - - - - - 65.2 - - - - - - (Table 4 continued on next page) 8,970.2 9,358.3 3,789.7 443.0 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. - - - - - - - - - - - - - - 26.4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 26.4 - - - - 5,535.6 1,754.1 1,664.9 4,676.5 2,064.0 231.7 171.2 3,110.6 2,573.4 41.4 764.1 22,587.6 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+ Forest Service Other Federal State and local government Private National Forest National Grassland National Park Service Bureau of Land Management Department of Defense or Energy State Local (county, municipal, etc.) Undifferentiated private 7,842.2 - - - - 720.0 28.3 305.4 50.5 2,490.6 Table 2--Area of accessible forest land by owner class and forest land status, Colorado, cycle 2, 2002-2006. (in thousand acres) 1,228.6 35.8 - - 3,867.7 84.0 348.3 19.3 2,960.1 9,070.8 35.8 - - 4,587.7 112.3 653.7 69.8 5,450.7 1,962.2 - - 176.5 41.7 - - - - - - - - (Table 2 continued on next page) 11,437.0 8,543.8 19,980.9 2,180.4 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. 68.4 - - 162.7 195.2 - - - - - - - - 2,030.7 - - 339.2 236.9 - - - - - - - - 11,101.4 35.8 339.2 4,824.5 112.3 653.7 69.8 5,450.7 426.4 2,606.7 22,587.6 Owner class Timberland Unproductive Total Productive Unreserved forests Reserved forests Unproductive Total All forest land
60 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked - - 875.1 676.3 2,672.5 1,343.9 140.2 2.9 1,965.0 - - - - 166.3 Table 4--Area of accessible forest land by forest type group, ownership group, and land status, Colorado, cycle 2, 2002-2006. (In thousand acres) 361.4 94.3 20.4 1,409.4 293.9 52.7 - - 352.3 647.5 12.0 51.3 - - 244.0 142.2 110.0 99.1 2.7 3.3 104.6 - - - - 42.3 3,433.1 - - 12.5 86.5 77.2 - - - - 80.9 593.0 29.3 215.2 (Table 4 continued on next page) 7,842.2 3,295.1 748.3 4,527.7 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. - - 61.8 60.5 80.9 53.1 - - 21.1 66.1 - - - - 12.5 224.8 - - - - - - 11.6 - - - - - - 122.4 - - 8.9 356.0 367.6 2,490.6 22,587.6 2,960.1 - - 478.9 753.2 317.2 175.8 36.1 140.6 499.4 - - - - 89.4 1,516.3 - - - - - - 9.5 - - 3.2 42.2 1,210.6 - - 178.3 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 5,535.6 1,754.1 1,664.9 4,676.5 2,064.0 231.7 171.2 3,110.6 2,573.4 41.4 764.1
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 61 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked 5,147.9 1,386.5 1,519.9 3,558.6 996.7 170.2 144.8 884.4 41.9 38.3 - - Table 5--Area of accessible forest land by forest type group and stand-size class, Colorado, cycle 2, 2002-2006. (In thousand acres) 131.1 311.2 84.4 761.8 875.5 45.8 23.1 1,715.0 139.4 3.0 - - 256.5 56.5 60.7 356.2 191.8 15.7 3.2 511.2 2,392.2 - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 5 continued on next page) 13,889.3 4,090.2 3,844.0 - - 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. - - - - - - - - - - - - - - - - - - - - 764.1 764.1 5,535.6 1,754.1 1,664.9 4,676.5 2,064.0 231.7 171.2 3,110.6 2,573.4 41.4 764.1 22,587.6 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest type group Non stocked All size classes Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked - - - - - - - - - - - - - - - - - - - - 764.1 Table 6--Area of accessible forest land by forest type group and stand-age class, Colorado, cycle 2, 2002-2006. (In thousand acres) 136.6 41.7 50.1 157.4 80.1 12.5 - - 313.7 1,808.4 - - - - 158.6 14.8 27.3 168.6 58.4 - - 13.5 164.5 527.4 - - - - 193.1 12.5 34.8 116.1 12.5 - - 12.8 204.5 72.1 - - - - (Table 6 continued on next page) 764.1 2,600.5 1,133.1 658.4 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. 445.7 239.9 247.0 311.1 209.0 11.2 69.5 872.3 48.7 - - - - 596.1 442.0 536.7 532.7 639.6 56.0 38.1 952.8 44.8 3.0 - - 596.4 342.2 544.7 917.8 578.7 30.5 26.6 431.4 28.7 - - - - 2,454.4 3,841.8 3,496.9 5,535.6 1,754.1 1,664.9 4,676.5 2,064.0 231.7 171.2 3,110.6 2,573.4 41.4 764.1 22,587.6 570.4 221.5 145.4 887.9 204.9 12.5 4.4 115.3 26.7 12.0 - - 557.9 161.6 15.5 716.1 86.5 36.8 - - 27.3 16.5 26.3 - - 851.2 167.0 13.6 431.2 80.1 46.6 2.9 28.8 - - - - - - 540.6 37.6 12.3 206.8 55.6 11.9 3.3 - - - - - - - - 889.0 73.5 37.5 230.9 58.8 13.6 - - - - - - - - - - 2,201.1 1,644.4 1,621.4 868.1 1,303.3 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+
62 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Pinyon-juniper group

Douglas-fir group

Ponderosa pine group

Fir-spruce-mountain hemlock group

Lodgepole pine group

Other western softwoods group

Elm-ash-cottonwood group

Aspen-birch group

Western oak group

Other western hardwoods group

Nonstocked

 5,535.6

 1,754.1

 1,664.9

 4,664.9

 2,064.0

 231.7

 171.2

 3,110.6

 2,573.4

 41.4

 764.1

Table 7--Area of accessible forest land by forest type group and 

 stand origin, Colorado, cycle 2, 2002-2006.

(In thousand acres)

 - -

 - -

 - -

 11.6

 - -

 - -

 - -

 - -

 - -

 - -

 - -

(Table 7 continued on next page)

All forest type groups 22,576.0 11.6

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.

 5,535.6

 1,754.1

 1,664.9

 4,676.5

 2,064.0

 231.7

 171.2

 3,110.6

 2,573.4

 41.4

 764.1

 22,587.6

Natural

stands

Artificial

regeneration

Stand origin

Forest type group

All forest

land
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 63 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked 5,017.6 1,539.5 1,399.8 4,218.4 1,659.0 207.3 143.8 2,773.1 2,228.9 41.4 524.7 Table 8--Area of forest land by forest type group and primary disturbance class, Colorado, cycle 2, 2002-2006. (In thousand acres) 387.3 84.1 135.0 215.2 192.1 21.7 - - 22.3 65.8 - - 58.6 39.5 46.6 43.2 132.9 144.0 - - 8.2 187.1 39.8 - - - - 27.7 12.8 14.2 61.9 17.3 2.7 - - 14.3 37.5 - - 15.2 (Table 8 continued on next page) 19,753.6 1,182.0 641.3 203.6 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. 14.1 39.7 72.7 37.0 24.7 - - - - 44.3 102.8 - - 156.5 36.1 6.5 - - 11.2 - - - - 19.1 33.8 88.0 - - 9.1 13.4 11.4 - - - - 26.8 - - - - 35.8 - - - - - - 491.9 203.7 87.4 5,535.6 1,754.1 1,664.9 4,676.5 2,064.0 231.7 171.2 3,110.6 2,573.4 41.4 764.1 22,587.6 - - 13.5 - - - - - - - - - - - - 10.6 - - - - 24.2 - - - - - - - - - - - - - - - - - - - - - - - - Forest type group All forest land None Insects Disease WeatheDristurbance class Fire Domestic animals Wild animals Human Other Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Nonstocked 1,317.0 1,487.0 2,353.8 751.3 140.6 144.8 840.4 - - Table 9--Area of timberland by forest type group and stand-size class, Colorado, cycle 2, 2002-2006. (In thousand acres) 298.0 84.4 591.7 755.6 22.7 23.1 1,376.5 - - 44.9 60.7 235.1 164.9 15.7 - - 418.3 - - - - - - - - - - - - - - - - - - (Table 5 continued on next page) 7,034.9 3,152.0 939.6 - - 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. - - - - - - - - - - - - - - 310.5 310.5 1,659.8 1,632.1 3,180.6 1,671.9 179.1 167.9 2,635.2 310.5 11,437.0 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest type group Non stocked All size classes
64 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Table 10--Number of live trees on forest land by species group and diameter class, Colorado, cycle 2, 2002-2006. (In thousand trees) (Table 10 continued on next page) 1,207,470 836,075 577,845 370,369 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. 223,041 12,719,775 Softwood species groups Hardwood species groups 867,079 340,390 639,952 196,123 459,975 117,870 306,471 63,898 194,471 28,570 6,273,652 6,446,124 All softwoods All hardwoods 133,386 11,310 85,268 3,825 52,501 1,665 51,162 1,208 20,264 430 7,579 157 2,409 69 1,005 76 144,696 89,093 54,166 52,370 20,694 7,736 2,478 1,081 1,282,590 958,232 2,240,821 2,169,540 4,722,301 6,891,841 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 7,498 6,926 6,240 23,306 4,540 35,557 1,202 3,825 4,718 4,176 4,374 13,066 924 24,338 905 1,589 76 4,886 3,254 2,550 12,206 161 27,431 674 1,122 86 1,189 1,155 758 5,260 11,647 255 430 700 369 729 1,003 4,777 157 215 151 277 1,766 69 70 935 76 509,966 290,535 1,368,711 1,518,335 1,135,198 1,324,740 126,168 1,670,015 4,971 4,771,138 160,307 63,760 689,035 529,939 285,246 400,588 40,666 635,187 1,947 4,085,166 101,304 32,697 283,060 309,451 290,480 235,258 30,340 377,169 974 580,089 71,318 45,364 159,351 199,978 215,867 156,168 19,032 251,517 837 88,037 42,603 35,464 57,444 109,762 100,649 104,925 9,128 115,056 151 2,664 59,347 38,495 97,533 153,267 151,553 126,565 13,191 183,435 226 12,462 28,007 28,607 36,860 75,547 48,841 83,414 5,195 61,627 452 1,819 14,967 18,831 20,013 50,964 25,466 60,793 3,438 27,813 232 526 12,838 11,285 10,764 34,309 11,472 50,576 2,142 10,943 154 214 Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Other western softwoods Cottonwood and aspen Other western hardwoods 62,837 37,629 119,426 127,480 181,188 12,519 171,217 69 Table 11--Number of growing stock trees on timberland by species group and diameter class, Colorado, cycle 2, 2002-2006. (In thousand trees) 51,723 34,218 74,537 100,664 125,352 8,758 136,718 37,027 32,366 43,981 70,630 79,254 6,104 94,331 23,417 25,427 28,901 48,919 36,739 2,360 53,776 75 (Table 11 continued on next page) 712,367 531,971 363,694 219,614 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. 13,369 16,615 15,964 32,423 17,856 2,440 25,705 214,762 170,538 303,332 434,592 453,555 35,157 497,507 220 124,372 2,109,663 Softwood species groups Hardwood species groups 541,080 171,287 395,252 136,718 269,363 94,331 165,762 53,851 98,667 25,705 1,611,936 497,727 All softwoods All hardwoods 10,960 10,495 8,731 20,862 8,691 1,235 9,787 75 5,988 5,827 4,874 13,705 3,687 826 3,199 3,936 3,564 3,678 7,661 628 552 1,359 3,465 2,937 2,313 8,054 161 288 981 1,053 1,005 532 3,303 75 288 700 304 395 694 77 215 151 196 69 70 60,974 9,863 34,909 3,199 20,018 1,359 17,217 981 5,968 288 2,093 77 562 69 70 - - 70,837 38,107 21,377 18,198 6,256 2,170 632 70 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 65 Forest Service Other federal State and local government Private National Forest National Grassland National Park Service Bureau of Land Management Department of Defense or Energy State Local (county, municipal, etc.) Undifferentiated private 19,674.1 - - - - 1,286.3 26.2 594.7 51.0 4,004.0 Table 12--Net volume of all live trees by owner class and forest land status, Colorado, cycle 2, 2002-2006. (In million cubic feet) 720.2 15.7 - - 2,645.2 30.9 178.6 7.3 1,279.7 20,394.3 15.7 - - 3,931.5 57.1 773.3 58.2 5,283.8 5,929.0 - - 509.7 76.5 - - - - - - - - (Table 12 continued on next page) 25,636.3 4,877.6 30,513.9 6,515.1 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. 25.0 - - 90.5 119.3 - - - - - - - - 5,954.0 - - 600.2 195.7 - - - - - - - - 26,348.3 15.7 600.2 4,127.2 57.1 773.3 58.2 5,283.8 234.8 6,749.9 37,263.8 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land
66 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked 4,178.0 2,652.4 2,205.1 13,127.7 3,068.7 231.5 274.6 3,083.2 46.7 11.9 - - Table 13--Net volume of all live trees on forest land by forest type group and stand-size class, Colorado, cycle 2, 2002-2006. (In million cubic feet) 43.6 403.5 71.2 1,521.5 2,112.6 31.0 7.9 3,236.1 64.9 0.7 - - 35.7 34.0 19.5 112.4 115.7 3.0 0.3 187.8 350.1 - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 13 continued on next page) 28,879.9 7,493.0 858.4 - - 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. - - - - - - - - - - - - - - - - - - - - 32.4 32.4 4,257.3 3,089.9 2,295.7 14,761.7 5,297.1 265.5 282.8 6,507.1 461.7 12.5 32.4 37,263.8 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest type group Non stocked All size classes
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 67 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods 2,055.9 1,117.5 3,636.5 9,857.7 4,725.0 320.9 376.4 4,206.0 1.4 66.6 Table 14--Net volume of all live trees on forest land by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 418.0 156.3 160.2 518.4 443.0 2,783.2 42.1 240.8 - - 22.5 80.1 107.2 50.5 128.5 119.2 151.5 1.9 191.3 - - 1.5 (Table 14 continued on next page) 26,364.0 4,784.5 831.5 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. 743.8 1,175.7 350.2 519.5 356.7 1,072.9 37.7 936.8 8.9 81.4 3,297.9 2,556.8 4,197.3 11,024.0 5,643.8 4,328.5 458.1 5,574.9 10.3 172.0 5,283.8 37,263.8 Softwood species groups Hardwood species groups 22,090.0 4,274.0 4,521.2 263.3 638.8 192.8 4,256.6 1,027.2 31,506.5 5,757.2 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
68 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods 125 76 331 428 612 171 29 513 1 106 Table 15--Net volume of all live trees on forest land by species group and diameter class, Colorado, cycle 2, 2002-2006. (In million cubic feet) 283 163 561 853 1,100 287 55 1,027 0 33 401 284 635 1,210 1,377 407 73 1,293 1 11 437 385 683 1,395 1,039 484 67 1,141 4 12 2,391 4,362 5,692 5,646 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. 353 381 552 1,452 747 481 66 756 2 5 3,298 2,557 4,197 11,024 5,644 4,328 458 5,575 10 172 4,796 37,264 Softwood species groups Hardwood species groups 1,772 620 3,302 1,060 4,388 1,305 4,490 1,157 4,032 764 31,507 5,757 All softwoods All hardwoods 429 318 409 1,414 453 523 54 387 2 2 343 260 323 1,286 236 446 37 170 269 219 275 927 64 375 31 97 1 374 225 221 1,158 15 543 29 89 2 124 144 79 684 311 19 40 105 63 128 161 172 12 39 38 57 76 13 16 53 37 3,599 392 2,932 170 2,160 98 2,564 91 1,362 40 628 12 210 13 69 37 3,991 3,102 2,258 2,655 1,401 640 223 106 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 69

Pinyon-juniper group

Douglas-fir group

Ponderosa pine group

Fir-spruce-mountain hemlock group

Lodgepole pine group

Other western softwoods group

Elm-ash-cottonwood group

Aspen-birch group

Western oak group

Other western hardwoods group

Nonstocked

 4,257.3

 3,089.9

 2,295.7

 14,761.7

 5,297.1

 265.5

 282.8

 6,507.1

 461.7

 12.5

 32.4

Table 16--Net volume of all live trees on forest land by forest type group and 

 stand origin, Colorado, cycle 2, 2002-2006.

(In million cubic feet)

 - -

 - -

 - -

 - -

 - -

 - -

 - -

 - -

 - -

 - -

 - -

(Table 7 continued on next page)

All forest type groups 37,263.8 - -

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.

 4,257.3

 3,089.9

 2,295.7

 14,761.7

 5,297.1

 265.5

 282.8

 6,507.1

 461.7

 12.5

 32.4

 37,263.8

Natural

stands

Artificial

regeneration

Stand origin

Forest type group

All forest

land
70 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Other western softwoods Cottonwood and aspen Other western hardwoods 110 66 253 285 525 19 378 0 Table 17--Net volume of growing stock trees on timberland by species group and diameter class, Colorado, cycle 2, 2002-2006. (In million cubic feet) 247 150 430 580 922 39 813 345 263 490 803 1,097 50 1,106 363 346 537 920 801 33 1,034 1 1,636 3,180 4,155 4,036 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. 318 342 445 951 541 49 706 2,770 2,308 3,312 7,125 4,493 287 4,754 2 3,352 25,051 Softwood species groups Hardwood species groups 1,258 378 2,367 813 3,049 1,106 3,001 1,035 2,646 706 20,295 4,756 All softwoods All hardwoods 364 299 333 890 349 32 355 1 270 227 254 780 196 26 149 222 190 237 566 46 20 86 262 200 202 769 15 14 81 107 131 63 427 5 24 105 57 69 113 9 39 38 42 13 16 2,267 356 1,754 149 1,280 86 1,462 81 733 24 343 9 119 13 16 - - 2,623 1,903 1,366 1,543 757 352 132 16 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 71 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Other western softwoods Cottonwood and aspen Other western hardwoods 1,639.1 1,025.2 2,784.9 6,221.8 3,844.7 229.1 3,558.3 1.4 Table 18--Net volume of growing stock trees on timberland by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 352.1 125.9 135.2 255.6 201.9 18.6 174.2 - - 68.7 99.0 50.3 128.5 102.3 1.9 186.7 - - (Table 18 continued on next page) 19,304.5 1,263.5 637.3 All species groups All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume round to less than 0.1 million cubic feet. Columns and rows may not add to their totals due to rounding. 709.8 1,057.8 341.7 519.3 344.5 37.1 834.7 0.7 2,769.7 2,307.9 3,312.1 7,125.1 4,493.4 286.7 4,754.0 2.1 3,845.5 25,051.0 Softwood species groups Hardwood species groups 15,744.9 3,559.7 1,089.3 174.2 450.6 186.7 3,010.1 835.4 20,294.9 4,756.1 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
72 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Other western softwoods Cottonwood and aspen Other western hardwoods Table 19--Net volume of sawtimber trees (International 1/4 inch rule) on timberland by species group and diameter class, Colorado, cycle 2, 2002-2006. (In million board feet) 1,231 814 1,931 3,248 4,060 124 1,597 1,390 2,491 4,354 3,479 111 4,586 1 11,409 18,010 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. International 1/4 inch rule. 1,521 1,544 2,200 4,872 2,570 193 3,348 11,573 9,625 12,758 32,501 13,171 879 11,452 7 16,248 91,965 Softwood species groups Hardwood species groups 11,409 - - 13,422 4,588 12,900 3,348 80,506 11,459 All softwoods All hardwoods 1,828 1,443 1,683 4,722 1,721 140 1,721 5 1,376 1,150 1,326 4,248 1,025 124 761 1,146 992 1,259 3,157 229 94 442 1,418 1,048 1,129 4,456 85 66 412 598 725 354 2,515 26 94 553 319 385 658 37 234 200 270 51 71 11,538 1,727 9,250 761 6,877 442 8,203 412 4,218 94 1,914 37 704 51 71 - - 13,264 10,010 7,319 8,615 4,312 1,951 755 71 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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 1 1
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 73 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Other western softwoods Cottonwood and aspen Other western hardwoods 1,297.8 840.7 1,954.6 4,853.4 2,436.7 170.5 1,388.6 1.1 Table 20--Net volume of sawtimber trees on timberland by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 262.4 105.0 97.8 208.0 66.6 13.5 38.9 - - 49.7 73.1 24.1 92.7 71.1 1.2 69.7 - - 12,943.5 792.2 381.6 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. 537.4 811.6 236.6 385.1 208.4 27.1 339.4 0.5 2,147.3 1,830.4 2,313.1 5,539.2 2,782.8 212.3 1,836.6 1.6 2,545.9 16,663.2 Softwood species groups Hardwood species groups 11,553.8 1,389.7 753.3 38.9 311.9 69.7 2,206.1 339.8 14,825.0 1,838.2 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
74 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Forest Service Other federal State and local government Private National Forest National Grassland National Park Service Bureau of Land Management Department of Defense or Energy State Local (county, municipal, etc.) Undifferentiated private 129.5 - - - - 3.9 0.6 9.4 0.9 45.3 Table 21--Average annual net growth of all live trees by owner class and forest land status, Colorado, cycle 2, 2002-2006. (In million cubic feet) 4.9 0.1 - - 9.5 0.3 -4.1 0.0 6.9 134.5 0.1 - - 13.3 0.9 5.3 0.9 52.2 6.4 - - 3.2 1.4 - - - - - - - - 189.6 17.5 207.0 11.0 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. 0.7 - - 0.6 0.3 - - - - - - - - 7.1 - - 3.8 1.7 - - - - - - - - 141.6 0.1 3.8 15.0 0.9 5.3 0.9 52.2 1.6 12.6 219.6 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 75 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Other western hardwoods group Nonstocked 15.4 22.3 20.8 35.0 13.3 2.4 1.0 29.6 0.8 0.1 - - Table 22--Average annual net growth of all live trees on forest land by forest type group and stand-size class, Colorado, cycle 2, 2002-2006. (In million cubic feet) 0.8 8.3 1.7 30.1 9.2 0.6 0.3 52.0 2.8 0.0 - - -0.4 0.2 0.5 1.6 2.5 0.0 0.0 1.1 1.0 - - - - - - - - - - - - - - - - - - - - - - - - - - 140.6 105.6 6.5 - - 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. - - - - - - - - - - - - - - - - - - - - -33.4 -33.4 15.7 30.7 23.0 66.7 25.0 3.0 1.3 82.7 4.6 0.2 -33.4 219.5 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest type group Non stocked All size classes
76 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods 9.2 0.7 -8.7 63.1 15.2 0.6 4.7 54.1 0.0 2.7 Table 23--Average annual net growth of all live trees on forest land by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 5.2 -1.6 -1.8 7.9 -2.8 8.5 0.2 3.1 - - 1.0 1.9 -2.6 0.7 2.1 0.3 0.2 -0.2 3.8 - - 0.0 141.6 19.6 6.2 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. 9.5 14.1 1.9 9.2 4.3 0.6 0.6 8.7 0.1 3.2 25.8 10.6 -7.9 82.3 17.0 9.9 5.3 69.7 0.1 7.0 52.2 219.6 Softwood species groups Hardwood species groups 84.8 56.8 15.5 4.2 2.3 3.8 40.2 11.9 142.9 76.7 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 77 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods 4.4 -0.7 -1.5 58.5 17.1 - - 2.5 43.2 0.0 - - Table 24--Average annual net growth of growing stock trees on timberland by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 3.7 -2.2 -1.2 3.3 -2.2 - - 0.3 2.1 - - - - 1.6 1.4 0.6 2.1 0.9 - - -0.2 3.7 - - - - 123.6 3.9 10.1 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. 8.4 12.2 1.8 9.1 3.9 - - 0.6 7.2 0.0 - - 18.1 10.8 -0.3 73.0 19.8 - - 3.3 56.2 0.0 - - 43.3 180.8 Softwood species groups Hardwood species groups 80.4 43.3 1.8 2.1 6.4 3.7 36.1 7.2 124.6 56.2 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
78 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Forest Service Other federal State and local government Private National Forest National Grassland National Park Service Bureau of Land Management Department of Defense or Energy State Local (county, municipal, etc.) Undifferentiated private 236.9 - - - - 22.4 0.1 2.9 - - 34.1 Table 25--Average annual mortality of all live trees by owner class and forest land status, Colorado, cycle 2, 2002-2006. (In million cubic feet) 8.4 - - - - 11.8 0.0 6.0 0.1 10.9 245.4 - - - - 34.1 0.1 8.9 0.1 45.0 80.7 - - 5.5 0.4 - - - - - - - - 296.4 37.2 333.5 86.5 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. 0.1 - - 0.2 0.5 - - - - - - - - 80.8 - - 5.7 0.8 - - - - - - - - 326.2 - - 5.7 35.0 0.1 8.9 0.1 45.0 0.8 87.3 420.8 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 79 Pinyon-juniper group Douglas-fir group Ponderosa pine group Fir-spruce-mountain hemlock group Lodgepole pine group Other western softwoods group Elm-ash-cottonwood group Aspen-birch group Western oak group Nonstocked 17.3 19.2 18.4 167.9 32.1 0.9 2.9 26.6 0.1 - - Table 26--Average annual mortality of all live trees on forest land by forest type group and stand-size class, Colorado, cycle 2, 2002-2006. (In million cubic feet) 0.2 2.0 1.2 9.6 39.0 0.2 - - 26.8 0.1 - - 1.2 0.8 - - 2.2 3.4 - - - - 4.7 9.7 - - - - - - - - - - - - - - - - - - - - - - 285.4 79.0 21.9 - - 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. - - - - - - - - - - - - - - - - - - 34.6 34.6 18.6 22.1 19.6 179.6 74.4 1.1 2.9 58.1 9.8 34.6 420.8 Large diameter Medium diameter Small diameter Chaparral Stand-size class Forest type group Non stocked All size classes
80 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Western woodland hardwoods 25.9 18.3 90.3 89.1 63.0 2.4 1.3 35.7 0.4 Table 27--Average annual mortality of all live trees on forest land by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 2.5 4.5 6.3 1.0 12.2 11.6 0.4 2.1 0.1 0.0 4.3 0.6 0.4 1.9 1.0 0.3 0.4 - - 326.4 40.8 8.9 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. 4.4 7.2 7.8 0.8 3.0 9.8 - - 11.5 0.4 32.9 34.3 105.0 91.3 80.0 24.9 2.0 49.7 0.9 44.9 421.0 Softwood species groups Hardwood species groups 290.4 36.0 38.5 2.3 8.5 0.4 33.0 11.9 370.3 50.7 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 81 Western softwood species groups Western hardwood species groups Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Western woodland hardwoods 24.7 17.4 66.3 45.3 49.6 - - 1.2 30.1 - - Table 28--Average annual mortality of growing stock trees on timberland by species group and ownership group, Colorado, cycle 2, 2002-2006. (In million cubic feet) 2.5 4.5 4.8 0.0 8.7 - - - - 1.6 - - 0.0 - - 0.6 0.4 1.2 - - 0.3 0.4 - - 234.5 22.0 2.9 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. 4.4 6.5 7.8 0.8 3.0 - - - - 10.7 - - 31.7 28.4 79.4 46.4 62.4 - - 1.5 42.8 - - 33.2 292.6 Softwood species groups Hardwood species groups 204.4 30.1 20.5 1.6 2.5 0.4 22.5 10.7 249.8 42.8 All softwoods All hardwoods Forest Service Other federal State and local government Species group Undifferentiated private All owners Ownership group
82 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Forest Service Other federal State and local government Private National Forest National Grassland National Park Service Bureau of Land Management Department of Defense or Energy State Local (county, municipal, etc.) Undifferentiated private 345,128 - - - - 24,386 566 10,713 1,040 76,513 Table 29--Aboveground dry weight of all live trees by owner class and forest land status, Colorado, cycle 2, 2002-2006. (In thousand dry tons) 16,970 289 - - 51,953 663 3,599 255 30,624 362,098 289 - - 76,338 1,229 14,312 1,295 107,137 99,206 - - 8,769 1,359 - - - - - - - - 458,345 104,353 562,697 109,334 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. 683 - - 1,985 2,233 - - - - - - - - 99,890 - - 10,754 3,592 - - - - - - - - 461,988 289 10,754 79,930 1,229 14,312 1,295 107,137 4,902 114,236 676,933 Timberland Unproductive Total Productive Unreserved forests Owner class Reserved forests Unproductive Total All forest land
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 83 Western softwood species groups Western hardwood species groups Table 30--Aboveground dry weight of all live trees on forest land by species group and diameter class, Colorado, cycle 2, 2002-2006. (In thousand dry tons) 50,595 75,979 94,664 93,208 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. 78,092 676,933 Softwood species groups Hardwood species groups 38,223 12,372 57,639 18,340 72,515 22,149 73,268 19,939 64,983 13,110 560,514 116,419 All softwoods All hardwoods 57,841 6,848 46,994 2,955 34,996 1,651 25,759 938 15,652 581 12,893 608 9,166 - - 15,874 895 64,688 49,949 36,647 26,697 16,233 13,501 9,166 16,770 24,160 9,076 33,235 10,551 6,957 17,508 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 6,296 5,173 4,825 18,206 3,642 8,189 663 2,955 4,945 4,337 4,230 13,066 971 6,842 605 1,601 49 4,796 3,258 1,920 9,851 226 5,429 279 891 47 2,029 1,224 1,409 6,270 4,443 276 581 1,263 1,600 661 6,113 2,966 290 608 1,016 1,192 781 3,507 2,609 61 3,053 2,044 2,083 3,307 5,387 895 67,587 51,260 76,619 174,808 99,658 81,169 9,414 99,294 284 16,840 882 319 3,771 3,180 1,426 771 203 1,270 4 5,683 2,482 654 6,086 6,653 5,810 1,868 607 3,583 9 5,483 3,264 2,153 6,767 8,732 13,018 3,458 831 8,797 19 3,556 8,128 5,330 10,012 19,022 21,407 7,336 1,280 21,788 20 342 6,167 3,253 9,480 14,591 17,763 5,358 1,026 17,287 13 1,040 8,530 7,237 10,354 20,941 16,393 8,621 1,192 19,455 105 379 6,735 7,296 8,111 21,215 11,917 8,543 1,166 12,879 60 170 8,001 6,190 6,127 20,154 7,084 9,350 935 6,702 54 91 Douglas-fir Ponderosa and Jeffrey pines True fir Engelmann and other spruces Lodgepole pine Western woodland softwoods Other western softwoods Cottonwood and aspen Other western hardwoods Western woodland hardwoods - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
84 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo Alamosa Conejos Eagle Grand Gunnison Hinsdale Jackson Mineral Pitkin Rio Grande Routt Saguache San Juan Summit 217.2 128.8 153.3 15.0 191.7 84.1 290.5 97.0 647.4 545.2 309.2 206.6 187.3 169.4 224.8 135.0 259.3 28.7 - - 193.7 349.0 637.8 852.0 220.2 310.5 270.1 219.2 211.3 647.7 605.7 68.2 154.7 Table 31--Area of accessible forest land by Forest Survey Unit, county and forest land status, Colorado, cycle 2, 2002-2006. (In thousand acres) - - 13.6 50.6 - - 46.6 9.5 31.9 13.6 50.4 35.0 - - 132.9 115.7 32.4 515.5 266.3 554.5 125.8 23.2 17.6 229.1 33.4 139.9 15.3 14.4 3.0 75.8 24.9 114.1 181.9 - - - - 217.2 142.4 203.9 15.0 238.3 93.6 322.4 110.6 697.7 580.2 309.2 339.6 303.1 201.7 740.4 401.3 813.8 154.5 23.2 211.3 578.1 671.2 991.9 235.5 325.0 273.1 295.0 236.2 761.8 787.6 68.2 154.7 16.4 26.1 - - - - - - - - - - 19.1 182.5 98.5 - - 26.1 - - 42.3 12.8 54.8 15.6 - - 11.6 45.8 104.7 104.9 242.5 219.8 72.2 126.8 126.1 - - 118.2 103.5 36.7 70.3 - - - - - - - - - - - - - - - - - - 12.5 - - - - - - - - - - - - - - - - - - - - 6.8 7.2 46.3 - - - - - - - - - - - - 11.9 - - - - 16.4 26.1 - - - - - - - - - - 19.1 182.5 111.1 - - 26.1 - - 42.3 12.8 54.8 15.6 - - 11.6 45.8 111.5 112.0 288.8 219.8 72.2 126.8 126.1 - - 118.2 115.4 36.7 70.3 233.6 168.5 203.9 15.0 238.3 93.6 322.4 129.7 880.3 691.3 309.2 365.6 303.1 244.1 753.1 456.1 829.5 154.5 34.7 257.1 689.6 783.2 1,280.8 455.3 397.2 399.9 421.0 236.2 880.0 903.0 104.9 225.0 Timberland Unproductive Total Productive Unreserved forests Forest Survey Unit and county Reserved forests Unproductive Total All forest land

(Table 31 continued on next page)

 2,679.5 1,211.1 4,740.2

 251.2

 1,743.2

 872.5

 2,930.7 2,954.3 5,612.7

 342.6 151.6

 1,383.1

TotalTotalTotal

 12.5

 - -

 72.1

 355.2 151.6

 1,455.3

 3,285.8 3,105.9 7,067.9

Northern Front Range

Southern Front RangeWest Central
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 85 Archuleta Delta Dolores Garfield La Plata Mesa Moffat Montezuma Montrose Ouray Rio Blanco San Miguel Arapahoe Baca Bent Otero 423.4 131.9 174.6 371.6 370.0 356.8 91.3 226.1 131.8 103.0 275.1 139.4 11.0 - - - - - - 228.5 193.7 224.7 700.4 360.6 866.2 457.6 392.7 785.6 117.8 914.8 350.1 - - 23.9 12.5 47.8 651.9 325.6 399.3 1,072.1 730.6 1,223.0 549.0 618.9 917.4 220.8 1,189.9 489.6 11.0 23.9 12.5 47.8 82.5 - - 13.5 134.0 25.0 - - - - - - - - 20.4 14.1 13.4 - - - - - - - - (Table 31 continued) 11,437.0 8,543.8 19,980.9 2,180.4 All counties - - 9.8 - - - - - - 61.3 68.4 156.4 31.7 - - 14.1 - - - - - - - - - - 82.5 9.8 13.5 134.0 25.0 61.3 68.4 156.4 31.7 20.4 28.2 13.4 - - - - - - - - 734.4 335.4 412.9 1,206.1 755.6 1,284.3 617.4 775.3 949.0 241.2 1,218.1 503.0 11.0 23.9 12.5 47.8 426.4 2,606.7 22,587.6 Timberland Unproductive Total Productive Unreserved forests Forest Survey Unit and county Reserved forests Unproductive Total All forest land 2,795.3 11.0 5,592.8 84.2 8,388.1 95.1 303.0 - - Total Total 341.7 - - 644.7 - - 9,032.8 95.1 Western Eastern 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.
86 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo - - 38.8 - - - - - - 12.0 46.5 - - 34.8 8.9 12.8 - - - - 10.6 28.9 - - - - - - Table 32--Area of accessible forest land by Forest Survey Unit, county, ownership group and forest land status, Colorado, cycle 2, 2002-2006. (In thousand acres) - - - - 2.7 - - 23.1 - - 18.1 - - 21.4 - - - - 12.7 - - 10.6 42.7 - - 60.5 28.7 77.9 50.9 24.5 15.0 76.1 12.0 152.2 42.7 167.3 132.0 133.5 20.9 187.3 52.9 49.0 42.7 243.6 - - - - - - 48.0 - - 1.7 9.5 13.8 - - - - 11.2 - - 30.9 115.7 21.8 97.3 210.7 460.0 91.0 233.6 168.5 203.9 15.0 238.3 93.6 322.4 129.7 880.3 691.3 309.2 365.6 303.1 244.1 753.1 456.1 829.5 154.5 (Table 32 continued on next page) 153.8 39.5 65.2 155.1 884.2 596.5 84.2 1,027.4 Total Total 3,285.8 3,105.9 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 139.4 39.1 128.8 - - 87.2 60.1 91.8 43.4 445.3 393.9 150.1 182.5 - - 105.9 47.9 69.2 15.6 28.7 - - 39.7 - - - - - - - - - - 32.7 149.2 134.8 - - 58.6 - - 42.3 44.7 60.6 15.6 - - - - - - - - - - 28.3 - - - - 10.9 - - 10.4 12.8 3.2 - - - - 99.0 23.1 - - - - 16.4 - - - - - - 21.8 - - - - - - 62.3 - - - - 56.7 - - - - 343.6 49.9 34.0 6.1 1,579.0 449.8 356.4 221.9 62.4 125.3 100.5 490.3 Forest Survey Unit and county Northern Front Range Southern Front Range
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 87 Alamosa Conejos Eagle Grand Gunnison Hinsdale Jackson Mineral Pitkin Rio Grande Routt Saguache San Juan Summit Archuleta Delta Dolores Garfield La Plata Mesa Moffat Montezuma Montrose Ouray Rio Blanco San Miguel Arapahoe Baca Bent Otero - - 10.3 - - 9.5 - - - - 57.8 - - - - - - 32.2 3.0 - - - - - - - - - - - - - - - - - - 18.4 14.1 - - 6.4 - - 11.0 - - - - - - - - 12.3 13.5 - - 11.6 - - - - - - - - - - - - - - - - - - - - 9.8 19.0 - - 25.0 - - 12.6 31.5 - - - - - - - - - - 11.9 - - - - - - - - 20.3 89.5 114.7 15.3 40.4 4.4 36.4 10.3 109.9 35.7 - - 19.7 96.9 18.5 - - 70.3 60.3 67.0 36.6 14.2 39.0 60.7 - - 49.7 - - - - - - - - - - 5.2 90.2 4.7 49.2 - - 2.9 - - 12.1 3.4 87.9 23.8 - - - - 161.5 77.0 36.9 154.6 309.8 85.1 73.3 271.1 76.0 90.0 119.0 78.4 - - - - 12.5 23.9 (Table 32 continued) 34.7 257.1 689.6 783.2 1,280.8 455.3 397.2 399.9 421.0 236.2 880.0 903.0 104.9 225.0 734.4 335.4 412.9 1,206.1 755.6 1,284.3 617.4 775.3 949.0 241.2 1,218.1 503.0 11.0 23.9 12.5 47.8 112.8 38.9 11.0 37.4 97.9 11.9 496.6 513.3 - - 279.6 1,532.6 36.4

Total

Total

Total

 7,067.9 9,032.8

 95.1

All

forest

land

Timberland

Other

forest

land

Timberland

Other

forest

land

Forest Service

Timberland

Other

forest

land

Timberland

Other

forest

land

Other federal

State and local

government

Undifferentiated

private

 - -

 171.1 311.8 488.9 646.1 162.9 174.7 265.7 182.8 190.3 452.9 530.9

 53.7

 135.0 312.8 113.4 174.6 183.5 309.7 289.7

 41.1

 179.3

 78.7 42.4

 246.4

 75.0

 - - - - - - - -

 11.6 45.8

 120.6

 59.6

 299.4 205.0

 83.8

 129.8 165.5

 21.4

 130.9 198.7

 36.7 70.3

 149.5

 9.8

 98.6

 159.5

 50.8

 199.0

 3.4

 90.2

 225.7

 33.3 42.4 39.7

 - -

 11.9

 - -

 23.9

 - -

 12.3 16.9 49.9 91.2 42.0 37.6

 - - - -

 10.7 52.7 36.1 14.5

 - -

 13.7

 - - - -

 117.9

 - - - -

 13.7 14.2

 - - - -

 22.3 14.8

 - - - - - - - -

 23.2

 - -

 116.3

 81.1 68.5 30.1

 - - - -

 24.3

 - -

 13.5 74.8

 - - - - - -

 106.9

 83.8

 520.4

 - -

 643.5 436.7 156.4 515.6

 15.0

 781.5 245.4

 - - - - - - - -

 3,766.8 2,046.5

 - -

 1,579.1 1,101.8

 35.8

 363.9 196.6

 - -

 431.7

 3,505.2

 - -

Forest Survey Unit and county

West CentralWesternEastern
88 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 (Table 32 continued) 356.0 367.6 2,490.6 2,960.1 All counties 22,587.6 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 7,842.2 3,295.1 748.3 4,527.7 Forest Survey Unit and county All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 89 Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo Conejos Eagle Grand Gunnison Hinsdale Jackson Mineral Pitkin Rio Grande Routt Saguache San Juan Summit 143.6 62.8 137.9 12.0 179.5 48.1 179.8 56.2 338.4 254.9 256.8 122.1 123.5 116.4 135.4 82.6 175.9 14.3 145.2 229.9 320.4 511.7 147.6 96.7 112.7 102.5 152.8 286.9 282.4 29.0 98.4 Table 33--Area of timberland by Forest Survey Unit, county and stand-size class, Colorado, cycle 2, 2002-2006. (In thousand acres) 46.6 54.3 10.6 - - - - 24.0 22.9 32.7 187.2 176.0 20.4 31.8 31.5 21.2 76.7 43.3 83.4 - - 36.9 89.3 269.7 248.7 45.9 147.3 98.3 80.3 58.5 315.4 221.9 24.7 45.0 27.0 11.7 - - - - 5.7 12.0 27.6 8.2 61.5 89.2 12.8 40.0 32.3 31.8 12.8 5.8 - - - - 11.6 27.5 47.7 68.5 26.7 60.7 59.1 36.4 - - 26.4 86.5 14.5 11.2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4.8 3.0 6.5 - - 60.3 - - 60.3 25.1 19.2 12.7 - - - - - - 3.3 - - 14.3 - - 2.3 - - 23.2 - - 5.8 - - - - - - 19.0 14.9 - - - - 217.2 128.8 153.3 15.0 191.7 84.1 290.5 97.0 647.4 545.2 309.2 206.6 187.3 169.4 224.8 135.0 259.3 28.7 193.7 349.0 637.8 852.0 220.2 310.5 270.1 219.2 211.3 647.7 605.7 68.2 154.7

(Table 33 continued on next page)

 1,669.9

 770.3

 2,516.3

 574.8 287.8

 1,682.0

 255.7 122.6 476.8

 - - - - - -

TotalTotalTotal

 179.1

 30.4 65.1

 2,679.5 1,211.1 4,740.2

Forest Survey Unit and county

Stand-size class

Chaparral

All

size classes

Small

diameter

Medium

diameter

Large

diameter Nonstocked

Northern Front Range

Southern Front RangeWest Central
90 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Archuleta Delta Dolores Garfield La Plata Mesa Moffat Montezuma Montrose Ouray Rio Blanco San Miguel Arapahoe 389.1 74.3 149.1 267.5 288.7 239.5 64.0 165.8 97.7 64.4 158.5 108.9 11.0 20.6 47.8 17.4 80.9 81.3 102.2 27.4 60.4 23.5 25.8 108.4 11.8 - - - - 9.8 8.1 9.4 - - 15.0 - - - - 10.6 12.9 - - 18.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Table 33 continued) 7,034.9 3,152.0 939.6 - - All counties 13.7 - - - - 13.9 - - - - - - - - - - - - 8.2 - - - - 423.4 131.9 174.6 371.6 370.0 356.8 91.3 226.1 131.8 103.0 275.1 139.4 11.0 310.5 11,437.0 2,067.4 11.0 607.5 - - 84.6 - - - - - - Total Total 35.9 - - 2,795.3 11.0 Forest Survey Unit and county Stand-size class Chaparral All size classes Small diameter Medium diameter Large diameter Nonstocked Western Eastern All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 91 Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo Conejos Eagle Grand Gunnison Hinsdale Jackson Mineral Pitkin Rio Grande Routt Saguache San Juan Summit 2.5 - - 4.8 3.0 6.5 - - 60.3 - - 61.8 25.1 28.7 12.7 - - - - - - 14.9 13.0 14.3 - - 15.8 - - 28.3 - - 5.8 - - - - - - 19.0 26.8 - - - - Table 34--Area of timberland by Forest Survey Unit, county and stocking class, Colorado, cycle 2, 2002-2006. (In thousand acres) 116.3 23.8 52.7 - - 97.1 - - 62.2 34.6 135.4 169.5 152.7 49.5 39.2 34.2 71.5 56.6 74.2 14.3 49.3 44.0 160.2 220.0 16.9 40.4 35.5 49.4 45.6 59.6 202.7 25.4 11.2 57.3 74.5 53.2 12.0 88.1 24.0 157.7 40.9 254.9 194.3 115.0 62.3 84.8 95.3 102.2 26.0 125.2 - - 46.0 121.6 274.9 224.3 84.1 161.9 91.7 48.5 69.3 271.0 151.5 3.6 73.1 24.7 13.6 42.6 - - - - 36.1 10.3 - - 182.7 153.6 12.8 53.4 57.0 18.7 51.1 23.1 46.9 - - 73.3 128.6 196.2 310.0 104.0 102.4 109.8 84.9 75.1 272.3 221.8 29.0 61.9 16.4 17.0 - - - - - - 24.0 - - 21.6 12.5 2.8 - - 28.6 6.4 21.2 - - 14.4 - - - - 25.2 39.0 6.5 69.4 15.3 - - 33.2 36.4 21.4 25.8 3.0 10.2 8.4 217.2 128.8 153.3 15.0 191.7 84.1 290.5 97.0 647.4 545.2 309.2 206.6 187.3 169.4 224.8 135.0 259.3 28.7 193.7 349.0 637.8 852.0 220.2 310.5 270.1 219.2 211.3 647.7 605.7 68.2 154.7 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)

 192.8

 54.9 95.7

 844.2 339.6 960.1

 1,071.8

 495.7

 1,621.5

 476.4 250.2

 1,769.1

TotalTotalTotal

 94.3 70.6

 293.9

 2,679.5 1,211.1 4,740.2

Northern Front Range

Southern Front RangeWest Central
92 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Archuleta Delta Dolores Garfield La Plata Mesa Moffat Montezuma Montrose Ouray Rio Blanco San Miguel Arapahoe 13.7 - - 8.1 14.2 12.5 - - - - - - - - - - 8.2 2.2 - - 126.7 38.1 29.2 156.7 78.2 93.8 41.1 80.5 53.1 25.8 3.5 26.6 11.0 145.6 19.5 69.6 104.1 143.9 72.6 26.3 81.1 47.0 38.6 137.2 28.8 - - 123.7 54.8 56.9 69.0 110.4 129.0 10.3 64.6 28.2 35.4 115.6 68.5 - - (Table 34 continued) 402.3 2,908.0 4,103.2 3,362.1 All counties 13.7 19.5 10.8 27.7 25.0 61.4 13.7 - - 3.5 3.2 10.6 13.4 - - 423.4 131.9 174.6 371.6 370.0 356.8 91.3 226.1 131.8 103.0 275.1 139.4 11.0 661.4 11,437.0 Nonstocked Poorly stocked Moderately stocked Fully stocked Forest Survey Unit and county Stocking class of growing-stock trees Over- stocked All classes 59.0 - - 753.1 11.0 914.2 - - 866.3 - - Total Total 202.7 - - 2,795.3 11.0 Western Eastern All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the acres round to less than 0.1 thousand acres. Columns and rows may not add to their totals due to rounding.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 93 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, Colorado, cycle 2, 2002-2006. 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 Front Range Southern Front Range 2,039.5 543.4 1,681.1 1,215.0 122.1 234.1 - - - - Total Total 3,842.7 1,992.5 6,360.5 1,795.9 6,212.9 4,723.7 142.4 426.4 - - - - 12,715.8 6,946.0 (Table 35 continued on next page) Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo 170.0 90.5 110.6 39.0 136.8 83.0 194.9 41.1 773.2 270.0 130.5 134.4 47.4 79.6 75.4 47.0 154.4 5.3 129.1 160.7 132.0 - - 84.7 125.2 125.5 145.7 242.5 338.7 197.0 306.6 216.8 219.0 243.1 82.1 142.1 5.3 0.7 2.5 13.5 - - 0.7 2.4 12.1 24.2 31.5 27.7 6.8 21.5 38.4 47.3 10.1 47.9 68.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 299.8 253.7 256.1 39.0 222.2 210.5 332.5 211.1 1,047.2 636.4 334.3 462.4 302.6 345.9 328.6 177.1 365.3 10.6 576.2 273.9 358.0 201.0 556.8 168.8 709.9 83.9 2,074.7 869.1 488.2 436.4 214.4 295.3 292.7 144.8 394.6 17.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 975.7 823.5 1,018.9 201.0 900.3 602.9 1,239.9 645.3 2,997.1 1,998.6 1,312.7 1,767.9 1,091.4 1,263.7 1,213.2 580.4 998.5 30.9 399.5 549.6 606.3 - - 343.4 434.1 492.5 561.4 886.9 1,119.8 819.4 1,286.8 839.0 900.7 920.5 306.2 457.4 13.1 - - - - 54.6 - - - - - - 37.4 - - 35.5 9.6 5.2 44.7 37.9 67.7 - - 129.4 146.6 - - (In million board feet) 1 (In million cubic feet)
94 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 (Table 35 continued) 7,088.0 13,206.9 4,730.3 25.8

All counties 25,051.0 23,674.3 56,831.5 11,358.7 100.5 91,964.9

Forest Survey Unit and county Pine

Other

soft

woods

Soft

hardwoods

Hard

hardwoods

Growing stock

All

species Pine

Other

soft

woods

Soft

hardwoods

Hard

hardwoods

All

species

Major species group

Sawtimber

Major species group

West CentralWesternEastern

 3,446.8 1,058.3

 - -

 6,284.1 4,026.6

 - -

 2,048.9 2,318.2

 7.0

 - -

 25.8

 - -

TotalTotalTotal

 11,779.8

 7,428.9

 7.0

 10,563.4

 4,954.4

 - -

 26,957.0 18,938.0

 - -

 4,140.2 6,617.5

 32.2

 - -

 100.5

 - -

 41,660.5 30,610.4

 32.2

All table cells without observations in the inventory sample are indicated by --. Table value of 0.0 indicates the volume rounds to lessthan 0.1 million cubic or board feet. Columns and rows may not add to their totals due to rounding. International 1/4 inch rule.

ConejosEagleGrandGunnisonHinsdaleJacksonMineralPitkinRio GrandeRouttSaguacheSan JuanSummitArchuletaDeltaDoloresGarfieldLa PlataMesaMoffatMontezumaMontroseOurayRio BlancoSan MiguelArapahoe

 30.8

 429.4 817.2 523.0

 20.2

 380.8

 13.5

 149.7

 10.6

 564.3 289.9

 - -

 217.4 148.5

 - -

 80.3

 - -

 373.4

 39.2 15.1

 171.4

 29.2

 - -

 165.1

 35.9

 - -

 561.4 520.1 475.9

 1,370.2

 359.0 180.4 528.4 259.9 388.3 687.9 538.8 137.2 276.7 777.0 323.6 322.8 618.4 431.2 536.0

 74.8

 242.2

 83.8

 167.9 295.7 153.2

 - -

 34.8

 130.4 150.8 377.7 133.9

 58.1

 205.5 105.1

 93.9

 579.5 137.1

 33.2

 8.9

 222.6 146.3 141.5 192.8 224.0 464.7 117.5 122.1 147.1

 73.2

 333.7 132.6

 7.0

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 4.8

 20.5

 - - - - - -

 0.5

 - - - -

 627.0

 1,080.0 1,443.9 2,270.9

 513.1 619.3 747.4 514.6 492.7

 1,831.7

 965.8 170.4 503.0

 1,148.2

 469.9 544.5 811.2

 1,028.6 1,044.7

 227.9 535.7 260.2 241.2 795.1 321.8

 7.0

 125.2

 1,675.6 2,259.0 1,574.9

 101.1 922.1

 33.9

 482.7

 43.3

 1,902.7

 804.9

 - -

 637.9 646.6

 - -

 353.3

 - -

 1,841.9

 186.5

 68.4

 790.8 115.7

 - -

 811.6 139.6

 - -

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 18.2 82.2

 - - - - - - - - - - - -

 2,714.1 4,232.9 4,445.2 8,559.5 1,899.8 1,729.7 2,728.3 1,931.4 1,855.3 6,037.6 2,966.4

 648.6

 1,911.6 5,150.0 1,917.0 2,426.3 3,280.3 4,619.4 3,946.0

 715.5

 2,184.3

 885.0

 1,025.3 3,109.7 1,351.6

 32.2

 2,552.2 2,243.5 1,898.6 6,125.3 1,543.5

 695.0

 2,381.3 1,142.6 1,558.1 2,974.0 1,986.6

 596.2

 1,260.1 3,755.9 1,583.9 1,547.0 2,842.9 2,171.5 2,475.8

 309.5

 1,178.8

 284.4 815.4

 1,226.7

 746.1

 - -

 36.7

 313.8 287.6 859.2 255.2 112.6 313.1 306.2 254.0

 1,160.8

 174.9

 52.5 13.7

 747.6 333.1 526.0 437.4 606.0

 1,265.5

 255.3 214.7 484.8 209.9

 1,071.4

 465.9

 32.2

(In million board feet) 1 (In million cubic feet)

1
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 95 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, Colorado, cycle 2, 2002-2006. 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 Front Range Southern Front Range 16.4 7.0 18.3 12.1 1.4 1.1 - - - - Total Total 36.2 20.2 84.1 28.8 109.2 75.4 3.2 13.4 - - - - 196.6 117.6 (Table 36 continued on next page) (In million cubic feet) (In million board feet) 1 Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo 2.3 1.5 -0.4 0.4 2.3 1.3 -4.9 0.9 13.3 3.0 -3.2 2.2 0.8 0.9 1.0 -1.7 3.7 0.1 1.6 2.6 0.4 - - 1.9 1.8 1.3 2.1 -0.6 5.2 2.0 4.0 3.7 1.8 1.9 2.0 2.6 -3.8 0.1 0.1 0.2 - - 0.1 0.2 0.3 0.5 0.0 0.2 -0.1 -0.7 0.5 -0.2 0.2 0.5 0.9 0.0 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3.9 4.2 0.1 0.4 4.3 3.3 -3.3 3.5 12.7 8.3 -1.3 5.4 4.9 2.4 3.2 0.8 7.2 -3.7 11.9 5.4 -2.4 3.4 12.0 9.1 -23.7 2.7 59.2 16.4 -10.0 9.6 3.4 4.2 3.7 -7.5 14.9 0.5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23.7 15.6 4.7 3.4 21.3 15.3 -9.3 18.0 55.2 43.2 5.4 25.3 29.2 19.9 24.7 4.2 32.2 -17.9 11.7 10.2 2.8 - - 9.6 6.2 13.6 15.3 -3.0 27.4 15.3 14.5 23.4 14.7 21.0 10.6 9.7 -18.4 - - - - 4.3 - - -0.2 - - 0.7 - - -1.0 -0.6 0.1 1.2 2.4 1.1 - - 1.2 7.6 - -
96 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 (Table 36 continued) Forest Survey Unit and county Pine

Other

soft

woods

Soft

hardwoods

Hard

hardwoods

Growing stock

All

species Pine

Other

soft

woods

Soft

hardwoods

Hard

hardwoods

All

species

Major species group

Sawtimber

Major species group

West CentralWesternEastern

1.98.4

 - -

31.728.7

 - -

28.424.7

0.3

 - -

0.3

 - -

TotalTotalTotal

62.062.2

0.3

58.057.6

 - -

241.3202.4

 - -

166.5247.4

1.5

 - -

2.1

 - -

465.7509.5

1.5

(In million cubic feet) (In million board feet) 1

AlamosaConejosEagleGrandGunnisonHinsdaleJacksonMineralPitkinRio GrandeRouttSaguacheSan JuanSummitArchuletaDeltaDoloresGarfieldLa PlataMesaMoffatMontezumaMontroseOurayRio BlancoSan MiguelArapahoeBacaBentOtero

 - -

0.66.4

-13.5

5.4

-0.1

1.10.52.40.2

-0.3

0.8

 - -

-1.5

2.4

 - -

1.3

 - -

3.40.3

-2.5

3.40.8

 - -

-1.4

0.7

 - - - - - - - -

 - -

1.8

-0.6

4.47.43.40.93.1

-12.7

6.86.97.21.81.23.7

-0.7

4.23.52.65.02.43.11.21.51.21.1

 - - - - - - - -

 - -

0.61.41.45.42.60.84.71.81.74.92.50.80.00.90.82.22.71.36.11.21.22.00.45.21.00.3

 - - - - - -

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

0.00.5

 - - - - - -

-0.2

 - - - - - - - - - -

 - -

3.07.1

-7.7

18.2

5.92.88.3

-8.5

8.7

11.610.4

2.6

-0.3

7.00.17.76.17.4

11.4

1.67.63.91.84.82.80.3

 - - - - - -

 - -

4.7

30.8

-54.1

27.4

-0.1

16.8

2.6

14.7

0.5

20.4

4.7

 - -

-10.5

13.6

 - -

8.2

 - -

24.1

1.9

-13.0

20.8

5.2

 - -

-5.9

2.7

 - - - - - - - -

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

0.12.0

 - - - - - - - - - - - - - - - - - -

 - -

25.769.8

-16.4

104.8

48.930.438.1

-39.8

49.092.258.3

8.6

-3.9

62.811.643.566.084.064.0

3.3

60.429.021.936.926.1

1.5

 - - - - - -

 - -

20.411.929.157.418.6

5.9

16.6

-60.2

42.640.044.9

7.76.5

27.6

6.0

28.228.819.629.611.518.5

2.8

15.6

9.05.2

 - - - - - - - -

 - -

0.6

27.2

8.6

20.030.4

7.7

19.0

5.75.8

31.8

8.70.90.1

21.6

5.67.1

37.240.432.4

2.8

21.021.0

6.2

33.718.3

1.5

 - - - - - -
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 97 (Table 36 continued) 33.8 90.8 55.9 0.3 All counties 180.8 228.4 628.3 431.9 2.1 1,290.8 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 (In million cubic feet) (In million board feet) 1 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. 1 International 1/4 inch rule.
98 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Northern Front Range Southern Front Range Boulder Clear Creek Douglas Elbert El Paso Gilpin Jefferson Lake Larimer Park Teller Chaffee Costilla Custer Fremont Huerfano Las Animas Pueblo - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 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, Colorado, cycle 2, 2002-2006. (Sampling error in percent) 51.54 46.75 83.55 - - 94.47 89.57 41.12 100.00 32.42 51.28 58.66 64.25 65.17 46.07 42.13 67.74 50.76 97.04 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 53.88 - - 90.01 - - 85.31 100.00 44.12 100.00 41.08 57.46 63.16 59.13 63.52 55.55 52.00 76.43 52.56 97.04 25.14 31.89 29.52 100.00 21.71 34.87 19.26 58.53 15.38 14.80 13.89 35.76 24.49 29.50 26.98 40.44 24.50 97.04 23.92 32.51 100.00 100.00 22.68 52.35 100.00 62.51 34.49 30.27 100.00 34.05 26.81 55.31 30.00 100.00 28.63 100.00 (Table 37 continued on next page) - - - - 20.43 28.66 - - - - 23.89 34.66 Total Total 7.36 13.14 22.62 24.47 6.47 11.56 8.20 83.92 10.70 2.91 6.83 13.67 4.19 6.33 6.21 8.54 11.48 9.02 4.37 8.61 6.66 20.26 9.13 20.04 17.85 83.92 14.95 15.36 9.28 25.06 8.13 9.10 6.21 17.66 19.07 16.90 18.92 26.32 18.17 64.19 21.26 26.72 25.74 100.00 20.27 27.13 18.28 43.25 12.73 14.11 13.10 29.93 22.63 27.50 24.78 35.39 22.45 97.04 36.66 24.40 100.00 100.00 25.92 35.99 100.00 33.84 28.29 35.08 100.00 36.13 22.34 73.33 44.35 100.00 21.00 100.00 2.39 3.11 3.71 7.86 6.36 11.25 26.12 28.68 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
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 99 West Central Western Eastern Alamosa Conejos Eagle Grand Gunnison Hinsdale Jackson Mineral Pitkin Rio Grande Routt Saguache San Juan Summit Archuleta Delta Dolores Garfield La Plata Mesa Moffat Montezuma Montrose Ouray Rio Blanco San Miguel Arapahoe Baca Bent Otero - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49.06 45.33 21.21 27.96 34.95 50.71 38.59 86.41 47.63 19.27 45.09 86.71 70.94 49.49 46.79 75.14 72.32 42.52 29.06 58.69 55.99 54.04 48.85 34.98 66.49 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 54.47 45.33 24.40 37.11 41.41 61.41 45.17 91.40 63.40 23.18 52.35 96.93 73.65 55.86 56.50 75.49 82.08 40.62 33.36 71.78 64.10 80.14 50.55 38.13 79.12 - - - - - - - - (Table Sampling errors that exceed 100% are reported as 100%. The sampling error is not calculated when the estimated value is equal to 0 and is indicated by --. 37 continued) - - 9.38 - - 11.54 All counties - - 28.82 19.30 12.89 15.39 24.21 19.48 28.29 33.48 23.01 14.42 15.85 44.51 31.69 18.67 39.72 25.12 23.84 18.05 22.56 40.74 24.73 39.22 33.94 27.05 34.05 100.00 - - - - - - - - 80.80 30.17 100.00 32.11 53.92 92.47 56.43 100.00 27.39 34.12 31.31 45.45 100.00 64.86 100.00 28.84 63.74 31.35 23.12 100.00 25.37 40.12 33.91 56.82 39.56 100.00 - - - - - - 4.00 11.79 - - - - - - 14.13 16.60 - - - - - - - - 17.36 20.18 - - Total Total Total 6.02 7.67 100.00 25.67 15.35 100.00 58.79 11.62 6.55 4.37 4.10 6.14 6.18 5.36 3.31 10.85 5.65 5.54 22.08 6.42 3.59 8.57 8.85 4.74 5.82 4.37 10.39 5.94 4.64 10.97 5.79 8.88 100.00 71.82 99.97 50.00 - - 17.52 14.06 6.80 7.76 17.89 11.42 13.30 16.35 12.93 8.17 9.52 35.58 17.40 12.17 24.92 20.78 15.43 13.09 16.21 35.04 19.09 28.43 27.71 18.16 25.96 100.00 - - - - - - - - 25.84 17.81 9.45 12.67 23.23 16.61 22.56 28.25 20.63 11.71 14.44 44.46 24.39 17.73 33.61 24.21 21.31 16.75 20.38 46.08 22.80 35.79 31.96 23.52 32.98 100.00 - - - - - - - - 100.00 65.43 100.00 30.10 33.22 100.00 38.10 100.00 24.72 52.42 33.00 50.00 100.00 94.07 100.00 26.25 100.00 57.59 24.23 100.00 32.05 39.40 60.27 76.45 54.10 100.00 - - - - - - 1.77 1.82 35.79 3.23 5.42 100.00 4.92 7.06 100.00 36.77 20.93 100.00 1.08 2.24 3.39 15.74 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
100 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Appendix E: Appendix E Tables____________________________________

Table E1—Maximum Stand Density Index by Forest Type.

Table E2—Mean water, carbon, and nitrogen contents of forest floor and soil cores by 

forest type, Colorado, 2002-2004.

Table E3a—Mean physical and chemical properties of soil cores by forest type, 

Colorado, 2000-2004.

Table E3b—Mean exchangeable cation concentrations in soil cores by forest type, 

Colorado, 2000-2004.

Table E3c—Mean extractable trace element concentrations in soil cores by forest type, 

Colorado, 2000-2004.

Table E4—Total roundwood output by product, species group, and source of material, 

Colorado, 2002.

Table E5—Volume of timber removals by source of material, species group, and removal 

type, Colorado, 2002.

Table E6—Quality Assurance results for condition-level variables from 81 conditions, 

Colorado, 2000-2006.

Table E7—Quality Assurance results for tree-level variables from 2,266 trees, Colorado, 2002-2006.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 101

Table E1—Maximum SDI by forest type.

182 Rocky Mountain juniper 425

184 Juniper woodland 385

185 Pinyon-juniper woodland 370

201 Douglas-fir 485

221 Ponderosa pine 375

261 White fir 500

265 Engelmann spruce 500

266 ES / SAF 485

268 Subalpine fir 470

269 Colorado Blue spruce 500

281 Lodgepole pine 530

362 Southwest white pine 450

365 Foxtail / bristlecone pine 470

366 Limber pine 410

703 Cottonwood 360

706 Sugarberry / hackberry / elm / green ash 504

901 Aspen 490

925 Deciduous oak woodland 475

953 Cercocarpus woodland 415

999 Unknown / nonstocked 475
102 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 Table E2— Mean water, carbon, and nitrogen contents of forest floor and soil cores by forest type, Colorado, 2000-2004. Number Forest Soil of Water Organic Inorganic Total C/N floor Organic Total Forest type layer plots contenta carbon carbon nitrogen ratio mass carbon nitrogen cm	 	 %	 %	 %	 %	 	 Mg/ha	 Mg/ha	 Mg/ha Deciduous oak woodland Forest floor 27 14.97 28.84 1.090 27.1 10.33 2.89 0.108 0–10 18 7.39 3.12 0.34 0.247 12.6 23.62 1.825 10–20 18 10.22 2.12 0.34 0.165 12.8 16.59 1.338 Pinyon/Juniperb group Forest floor 48 8.27 26.84 0.741 37.6 9.16 2.61 0.074 0–10 43 4.58 1.91 0.44 0.151 12.5 18.59 1.521 10–20 33 5.43 1.19 0.51 0.093 12.7 12.41 0.960 Ponderosa pine Forest floor 26 12.40 33.07 0.753 44.7 16.35 5.30 0.125 0–10 22 4.32 2.13 0.20 0.122 17.4 16.61 0.928 10–20 19 3.43 1.03 0.15 0.054 19.0 8.01 0.455 Lodgepole pine Forest floor 22 43.54 39.28 0.959 41.9 28.53 11.24 0.272 0–10 19 12.03 3.41 0.16 0.120 28.3 18.13 0.655 10–20 19 7.58 1.08 0.11 0.033 33.1 7.87 0.221 Douglas fir Forest floor 11 18.00 37.60 0.980 40.7 21.00 7.90 0.210 0–10 9 4.37 3.75 0.17 0.198 18.8 26.62 1.389 10–20 5 5.49 1.15 0.21 0.060 19.2 11.03 0.636 Aspen Forest floor 36 25.39 30.15 1.150 26.5 20.08 6.18 0.239 0–10 29 9.80 4.76 0.29 0.314 15.1 25.68 1.698 10–20 26 7.60 2.31 0.22 0.175 13.2 17.39 1.306 Spruce/Fir group Forest floor 45 37.13 34.10 1.034 34.3 24.83 8.56 0.261 0–10 29 16.35 5.13 0.24 0.238 21.7 18.32 0.912 10–20 21 11.55 2.30 0.19 0.108 21.3 15.82 0.749 Western softwoods group Forest floor 3 9.25 24.36 0.618 41.7 10.55 2.99 0.073 0–10 2 5.03 2.99 0.34 0.120 25.0 9.28 0.401 10–20 2 4.92 1.90 0.15 0.065 29.6 8.25 0.297 aWater content and forest floor mass are reported on an oven-dry weight basis (105 °C). bPinyon/Juniper group includes Rocky Mountain juniper, juniper woodland, and pinyon/juniper woodland; Spruce/Fir group includes white fir, Engelmann spruce, subalpine fir, mixed Engelmann spruce/subalpine fir, and blue spruce; Western softwoods group includes foxtail/bristlecone pines and limber pine.
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 103

Table E3a—Mean physical and chemical properties of soil cores by forest type, Colorado, 2000-2004.

Number Bray 1 Olsen

Soil of Bulk Coarse pH extractable extractable

Forest type layer plots SQIa density fragments H2O CaCl2 phosphorus phosphorus

cm	 	 %	 g/cm3	 %	 	 	 mg/kg	 mg/kg

Deciduous oak woodland 0–10 18 72 1.08 22.85 6.72 6.31 16.1 11.0

10–20 18 66 1.30 28.22 6.68 6.17 8.2 5.1

Pinyon/Juniper group 0–10 43 64 1.19 18.59 7.35 6.87 4.8 6.3

10–20 33 58 1.35 25.43 7.56 7.01 3.3 2.0

Ponderosa pine 0–10 22 65 1.24 32.54 6.32 5.72 16.7 6.8

10–20 19 57 1.54 38.94 6.49 5.81 11.0 3.0

Lodgepole pine 0–10 19 65 0.84 28.99 5.35 4.77 18.9 14.8

10–20 19 57 1.30 35.75 5.54 4.85 22.5 9.5

Douglas fir 0–10 9 71 0.90 42.98 6.55 6.05 40.8 19.4

10–20 5 66 1.21 50.04 6.45 5.77 31.3 10.2

Aspen 0–10 29 74 0.86 22.11 6.18 5.68 21.6 10.6

10–20 26 70 1.10 26.10 6.18 5.62 17.3 9.3

Spruce/Fir group 0–10 29 72 0.69 25.93 5.76 5.22 16.8 15.3

10–20 21 64 1.09 33.44 5.59 4.99 12.4 6.9

Western softwoods group 0–10 2 69 1.08 51.88 7.12 6.59 10.8 4.0

10–20 2 65 1.28 56.31 6.65 6.18 9.2 4.9

aSQI = Soil Quality Index

Table E3b—Mean exchangeable cation concentrations in soil cores by forest type, Colorado, 2000-2004.

Number

Soil of 1 M NH4CI Exchangeable cations

Forest type layer plots Na K Mg Ca AI ECEC

cm	 	 	 	 mg/kg	 	 	 cmolc/kg

Deciduous oak woodland 0–10 18 10 280 306 3507 1 21.78

10–20 18 19 231 299 3472 2 21.39

Pinyon/Juniper group 0–10 43 13 193 186 3599 1 20.58

10–20 33 22 142 188 3646 2 20.64

Ponderosa pine 0–10 22 10 155 194 1816 2 11.22

10–20 19 14 98 143 1367 1 8.39

Lodgepole pine 0–10 19 17 176 138 1174 57 8.44

10–20 19 16 118 97 765 65 6.03

Douglas fir 0–10 9 11 263 249 2686 1 16.45

10–20 5 13 233 273 2272 9 14.53

Aspen 0–10 29 8 350 259 2729 5 16.96

10–20 26 13 269 184 1965 4 12.33

Spruce/Fir group 0–10 29 30 261 263 2475 62 17.49

10–20 21 33 171 215 1546 78 12.97

Western softwoods group 0–10 2 21 401 186 2475 1 15.27

10–20 2 14 427 212 2259 0 14.23
104 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Table E3c—Mean extractable trace element concentrations in soil cores by forest type, Colorado, 2000-2004.

Number

Soil of 1 M NH4CI Extractable

Forest type layer plots Mn Fe ni Cu Zn Cd Pb S

cm	 	- - - - - - - - - - - - - - - - - - - - - - -mg/kg	- - - - - - - - - - - - - - - - - - - - - - -

Deciduous oak woodland 0–10 18 6.4 0.04 0.07 0.00 0.03 0.10 0.03 770.0

10–20 18 7.0 0.19 0.02 0.04 0.07 0.04 0.16 753.3

Pinyon/Juniper group 0–10 43 5.3 0.19 0.07 0.00 2.72 0.19 0.28 247.1

10–20 33 3.5 0.01 0.02 0.07 0.09 0.04 0.20 285.5

Ponderosa pine 0–10 22 22.9 0.04 0.04 0.00 0.43 0.11 0.15 6.1

10–20 19 9.6 0.10 0.02 0.05 0.19 0.06 0.14 5.8

Lodgepole pine 0–10 19 47.7 6.87 0.07 0.00 1.27 0.10 0.47 10.7

10–20 19 9.1 5.52 0.03 0.03 1.34 0.06 0.49 7.2

Douglas fir 0–10 9 15.9 0.04 0.04 0.00 0.16 0.15 0.22 10.0

10–20 5 5.0 0.02 0.05 0.02 0.03 0.03 0.23 5.5

Aspen 0–10 29 14.3 0.11 0.13 0.00 0.15 0.07 0.15 12.2

10–20 26 10.2 0.39 0.01 0.00 0.16 0.03 0.14 12.5

Spruce/Fir group 0–10 29 35.6 3.72 0.06 0.00 0.84 0.13 0.42 15.0

10–20 21 15.6 2.66 0.07 0.05 1.04 0.06 0.40 33.4

Western softwoods group 0–10 2 7.8 0.65 0.00 0.00 0.00 0.00 0.01 7.6

10–20 2 6.0 0.00 0.00 0.00 0.00 0.01 0.09 22.8
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 105

Table E4—Total roundwood output by product, species group, and source of material, 

Colorado, 2002 (in thousand cubic feet).

Source of material

 Product and Growing-stock trees

species group Sawtimber Poletimber Other sources All sources

Sawlogs

Softwood 7,106 931 2,574 10,610

Hardwood 927 122 613 1,661

Total 8,033 1,053 3,186 12,272

Veneer logs

Softwood 0 0 0 0

Hardwood 0 0 0 0

Total 0 0 0 0

Pulpwood

Softwood 0 0 0 0

Hardwood 0 0 0 0

Total 0 0 0 0

Composite Panels

Softwood 0 0 0 0

Hardwood 1,632 214 25 1,871

Total 1,632 214 25 1,871

Poles and posts

Softwood <0.5 302 96 399

Hardwood <0.5 3 3 6

Total <0.5 305 99 405

Other Miscellaneous

Softwood 514 67 700 1,282

Hardwood 28 4 97 129

Total 542 71 797 1,410

Total Industrial Products

Softwood 7,620 1,300 3,370 12,291

Hardwood 2,587 342 738 3,667

Total 10,207 1,642 4,108 15,958

Fuelwood

Softwood 1 <0.5 15,053 15,054

Hardwood <0.5 <0.5 3,928 3,928

Total 1 <0.5 18,981 18,983

All products

Softwood 7,621 1,301 18,423 27,345

Hardwood 2,587 342 4,666 7,596

Total 10,208 1,643 23,090 34,941
106 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Table E5—Volume of timber removals by source of material, species group, and removal type, Colorado, 2002 (in thousand cubic feet).

Source of material

Growing stock Other sources All sources

Removal type Softwoods Hardwoods Total Softwoods Hardwoods Total Softwoods Hardwoods Total

Roundwood products

Saw logs 8,037 1,049 9,086 2,574 613 3,186 10,610 1,661 12,272

Veneer logs

Pulpwood

Composite products 0 1,846 1,846 0 25 25 0 1,871 1,871

Fuelwood 1 <0.5 1 15,053 3,928 18,981 15,054 3,928 18,983

Posts, poles, and pilings 302 3 305 96 3 99 399 6 405

Miscellaneous products 581 31 613 700 97 797 1,282 129 1,410

Total roundwood products 8,922 2,929 11,851 18,423 4,666 23,090 27,345 7,596 34,941

Logging residues 493 162 655 2,456 513 2,969 2,949 675 3,624

Total timber removals 9,414 3,091 12,505 20,880 5,179 26,059 30,294 8,270 38,564
USDA Forest Service Resour. Bull. RMRS-RB-11. 2010 107

Table E6—QA results for condition-level variables from 81 conditions in Colorado 2002 to 2006.

Percentage of data Number of times data 

within tolerance exceeded tolerance

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

Condition status No tolerance 100.0% 0 81

Reserve status No tolerance 97.5% 2 81

Owner group No tolerance 98.8% 1 81

Forest type (Type) No tolerance 89.3% 8 75

Forest type (Group) No tolerance

Stand size No tolerance 86.7% 10 75

Regeneration status No tolerance 100.0% 0 75

Tree density No tolerance 100.0% 0 75

Condition nonsampled Reason No tolerance 100.0% 0 1

Owner class No tolerance 97.5% 2 81

Owner status No tolerance 100.0% 0 2

Regeneration species No tolerance

Stand age ±10 % 96.0% 96.0% 96.0% 97.3% 3 3 3 2 75

Disturbance 1 No tolerance 86.7% 10 75

Disturbance year 1 ±1 yr 40.0% 60.0% 60.0% 60.0% 3 2 2 2 5

Disturbance 2 No tolerance 75.0% 3 12

Disturbance year 2 ±1 yr

Disturbance 3 No tolerance 100.0% 0 3

Disturbance year 3 ±1 yr

Treatment 1 No tolerance 98.7% 1 75

Treatment year 1 ±1 yr 100.0% 0 1

Treatment 2 No Tolerance 50.0% 1 2

Treatment year 2 ±1 yr

Treatment 3 No tolerance 100.0% 0 1

Treatment year 3 ±1 yr

Physiographic class No tolerance 53.3% 35 75

Present nonforest use No tolerance 100.0% 0 5

Regional variables

Percent crown cover ±10 % 84.0% 94.7% 97.3% 98.7% 12 4 2 1 75

Percent bare ground ±10 % 86.7% 94.7% 94.7% 96.0% 10 4 4 3 75

Habitat type 1 No tolerance 37.3% 47 75

Habitat type 2 No tolerance 36.0% 48 75

Condition class number No tolerance 98.8% 1 81
108 USDA Forest Service Resour. Bull. RMRS-RB-11. 2010

Table E7—QA results for tree variables from 2,266 Trees in Colorado 2002 to 2006.

Percentage of data Number of times data 

within tolerance exceeded tolerance

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

DBH ±0.1 /20 in. 90.1% 94.8% 96.3% 97.0% 179 94 66 54 1799

DRC ±0.1 /20 in. 54.2% 66.0% 73.9% 79.7% 214 159 122 95 467

Azimuth ±10 o 97.5% 99.0% 99.1% 99.2% 57 22 20 18 2266

Horizontal distance ±0.2 /1.0 ft 88.5% 94.2% 96.6% 97.7% 261 131 77 53 2266

Species No tolerance 96.9% 71 2266

Tree genus

Tree status No tolerance 99.0% 22 2266

Rotten/Missing cull ±10 % 93.4% 97.3% 98.5% 99.0% 137 55 32 21 2065

Total length ±10 % 74.1% 91.8% 97.0% 98.8% 539 171 63 25 2080

Actual length ±10 % 65.9% 89.0% 96.3% 98.8% 28 9 3 1 82

Compacted crown ratio ±10 % 63.8% 88.9% 97.0% 99.0% 697 213 57 20 1923

Uncompacted crown ratio (P3) ±10 % 93.9% 98.6% 99.2% 99.8% 107 25 14 4 1764

Crown class No tolerance 75.8% 465 1923

Decay class ±1 class 94.9% 99.7% 100.0% 16 1 0 314

Cause of death No tolerance 57.1% 33 77

Mortality year ±1 yr 90.9% 100.0% 7 0 77

Condition class No tolerance 98.9% 24 2266

New tree No tolerance 93.5% 2 31

Regional variables

Mistletoe ±1 class 97.5% 99.0% 99.8% 99.9% 49 19 4 2 1923

Number of stems No tolerance 80.1% 93 467

Percent missing top ±10 % 97.9% 98.5% 99.0% 99.2% 44 30 20 16 2065

Sound dead ±10 % 85.9% 91.9% 94.6% 96.2% 291 168 111 79 2065

Form defect ±10 % 69.4% 84.1% 90.9% 93.6% 413 215 123 87 1350

Current tree class No tolerance 95.4% 104 2251

Radial growth ±1 /20 inch 48.5% 69.8% 82.3% 91.1% 230 135 79 40 447

Breast height tree age ±10 % 41.7% 69.4% 84.7% 93.2% 179 94 47 21 307

Total tree age ±10 % 28.3% 48.9% 58.7% 70.7% 66 47 38 27 92

DRC using IW MQO ±0.2 in/stem 75.8% 87.4% 92.1% 94.4% 113 59 37 26 467

Horiz Dist-timberland ±0.2 /1.0 ft 96.7% 98.8% 99.1% 99.3% 60 21 16 12 1799

Horiz Dist-woodland ±0.2 /1.0 ft 57.0% 76.4% 86.9% 91.2% 201 110 61 41 467

Total Length: Saplings ±10 % 73.1% 92.5% 98.4% 100.0% 50 14 3 0 186

Actual Length: Saplings ±10 % 100.0% 0 1

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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.

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