Area Changes for Forest Cover Types 

in the United States, 1952 to 1997, 

With Projections to 2050

A Technical Document Supporting the

2000 USDA Forest Service RPA Assessment

 U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICE

Area Changes for Forest Cover Types in the United States

1952 to 1997

With Projections to 2050

RALPH J. ALIG AND BRETT J. BUTLER
The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of 

multiple use management of the Nation’s forest resources for sustained yields of wood, 

water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide increasingly greater service to 

a growing Nation.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and 

activities on the basis of race, color, national origin, gender, religion, age, disability, political 

beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all 

programs.) Persons with disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET 

Center at (202) 720-2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-

W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or 

call (202) 720-5964 (voice and TDD). USDA is an equal opportunity provider and employer.

USDA is committed to making its information materials accessible to all USDA customers 

and employees.

Authors

Ralph J. Alig is a research forester, Pacific Northwest Research Station, Forestry 

Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331; Brett J. Butler

is a research forester, Northeastern Research Station, 11 Campus Boulevard, Suite 

200, Newton Square, PA 19073.
Abstract

Alig, Ralph J.; Butler, Brett J. 2004. Area changes for forest cover types in 

the United States, 1952 to 1997, with projections to 2050. Gen. Tech. Rep. 

PNW-GTR-613. Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 106 p.

The United States has a diverse array of forest cover types on its 747 million 

acres of forest land. Forests in the United States have been shaped by many natural 

and human-caused forces, including climate, physiography, geology, soils, water, 

fire, land use changes, timber harvests, and other human interventions. The major 

purpose of this document is to describe area projections of forest cover changes on 

timberland areas of the United States, in support of the 2000 Resources Planning 

Act assessment by the USDA Forest Service. Forest area projections differ markedly by region, owner, and forest cover type. Although some regions such as the 

North are projected to have relatively small percentage changes in common types 

such as maple-beech-birch (less than 5 percent), others in the South have relatively 

large projected changes: reductions of 19 percent for upland hardwood on nonindustrial private forest timberlands and 58 percent on forest industry timberlands in 

the South Central region; and increases in excess of 25 percent for planted pine for 

both private ownerships in the South. Although the area of softwoods is projected 

to increase across many regions of the country, especially on forest industry lands, 

hardwoods will remain the dominant forest type on private lands. 

Keywords: Forest land area, forest type transitions, succession, forest cover, 

timber harvesting, Renewable Resources Planning Act.
Contents

 1 Introduction

 5 Chapter 1: North

 5 Introduction

 7 Forest Cover Situation

 12 Projections

 18 Summary, North Region

 19 Chapter 2: South

 19 Introduction

 20 Forest Cover Situation

 24 Projections

 25 Planted Pine

 31 Naturally Regenerated Cover Types

 35 Summary, South Region

 39 Chapter 3: Rocky Mountains Region

 39 Introduction

 39 Forest Cover Situation

 43 Projections

 46 Summary, Rocky Mountains Region

 47 Chapter 4: Pacific Coast

 47 Introduction

 48 Forest Cover Situation

 53 Projections

 53 Douglas-Fir in the Pacific Northwest West Subregion

 57 Other Forest Cover Types in the Pacific Northwest West Subregion

 58 Forest Cover Projections for Other Subregions

 58 Summary, Pacific Coast Region

 61 Chapter 5: National Overview

 61 Introduction

 62 Macro View of Forest Cover Projections

 66 Relationships Between Land Use and Land Cover Changes

 68 Links to Other Resource Planning Act Assessment Models

 71 Sustainability Issues and Land-Based Policies 

 76 Summary, National Overview

 77 Acknowledgments

 77 Metric Equivalents

 77 References

 85 Appendix 1: Forest Cover Area Database and Forest Cover Area Studies

 95 Appendix 2: Species Diversity by Region

 105 Glossary
1

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Introduction

We examine land cover changes involving U.S. forests in support of the Forest and 

Rangeland Renewable Resources Planning Act (RPA) of 1974 (e.g., USDA Forest 

Service 2001), which directs the USDA Forest Service to conduct a periodic review 

of the Nation’s forest resources. The act requires that an assessment every decade 

include an analysis of present and anticipated uses; demand for and supply of the 

renewable resources of forest, range, and other associated lands; and an emphasis 

on pertinent supply, demand, and price relationship trends.1 Land cover change has 

important consequences for the future availability of timber, wildlife habitat, and 

other renewable resources and, therefore, is a critical component of this analysis. The 

major purpose of this document is to describe our projections of forest cover changes 

on timberland areas of the United States, in support of the 2000 RPA assessment (see 

“Glossary” for definitions of forest land and timberland). 

This report focuses on area changes for major forest cover types. Land cover

is the observed (bio)physical cover on the Earth’s surface, e.g., oak-hickory forest. 

Cover types are related to land use changes, but note that land use is the purpose 

to which land is put by humans, e.g., protected areas, forestry for timber products, 

plantations, row-crop agriculture, pastures, or human settlements (Di Gregorio and 

Jansen 1998). A companion general technical report (Alig et al. 2003) documents the 

projected land use changes for the 2000 RPA assessment.

To better understand forest dynamics, we analyzed historical trends of forestland area by forest cover type as a basis for making projections of future forest type 

distributions for private timberlands in the United States through 2050.2 This report 

is divided into sections so that the dynamics of each region can be examined independently. Some regions are further divided into subregions so that specific regional 

attributes can be isolated and comparisons can be made within a region. We use the 

four RPA regions of the United States: North, South, Rocky Mountains, and Pacific 

Coast (fig. 1). Table 1 lists the nine RPA subregions within the four regions. 

Based on empirical modeling, we provide projections of area changes for forest 

cover types by RPA region and by decade out to 2050 for major private forest ownership groups. Forest cover changes take place on a fixed total land base, with “forest 

1 Web sites for the 2000 RPA assessment (USDA Forest Service 2001) are http//www.fs.fed.

us/pl/rpa, and http//www.fs.fed.us/pnw/sev/rpa (2001 timber assessment, Haynes 2003).

2 Historical data pertaining to forest cover type areas sometimes include private and public 

forest-land estimates, but the majority at regional and national compilation levels are for private timberlands. This limits the foundation for making projections, and in this report we only 

discuss projections of changes in forest cover type areas on private timberland, but include 

examination of historical trends on public forest lands within an all-ownership context where 

data allow. 

Forest cover changes 

have important 

consequences for the 

future availability of 

timber, wildlife habitat, 

forest carbon, and 

other forest ecosystem 

goods and services in 

the United States.
2

General Technical Report PNW-GTR-613

Rocky 

Mountains

South

Pacific

Coast

Pacific

Southwest

Pacific

Northwest

Intermountain

Great Plains

North

North Central

Northeast

South Central

Southeast

Alaska

Figure 1—Regions and subregions used in the 2000 Resources Planning Act assessment (USDA Forest Service 2001).

Table 1—Regions and subregions used in the national Resources Planning Act assessment

Region Subregion States 

North Northeast Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, 

 New Jersey, New York, Pennsylvania, Rhode Island, Vermont, West Virginia

North Central Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, Wisconsin

South Southeast Florida, Georgia, North Carolina, South Carolina, Virginia

South Central Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Oklahoma, Tennessee, 

 Texas

Rocky Mountains Great Plains Kansas, Nebraska, North Dakota, South Dakota

Intermountain Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming

Pacific Coast Alaska Alaska

Pacific Northwest Oregon, Washington

Pacific Southwest California, Hawaii
3

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

land” as one of the major land use classes. Definitions of land uses and forest cover 

types can differ by source, and we use definitions and data from the Forest Inventory and Analysis (FIA) units of the USDA Forest Service (e.g., Smith et al. 2001; 

see “Glossary”). Our 50-year projections of area changes for forest cover types on 

private timberland are based on the historical data that quantify the areas of the 

major land use classes over the past 50 years.

We focus on forest cover changes on private ownerships. Private owners control 

more than 70 percent of U.S. timberland (Smith et al. 2001) and currently contribute 

more than 90 percent of U.S. timber harvest (Haynes 2003). We use forest industry 

and nonindustrial private forest (NIPF) ownership classes, where the former class 

has wood processing facilities (Smith et al. 2001) (see “Glossary” for definitions of 

ownership classes).

Area changes for forest cover types can differ markedly by ownership and can 

result from four basic sets of activities: afforestation, deforestation, shifts among 

forest cover types on retained timberland, and sales or exchanges of land among 

ownership groups. In contrast to ecological processes, land cover changes and disturbances can differ significantly by type of private ownership. Ownership changes 

in the timberland base may result in new owners with different land management 

objectives or different access to types of technology or available resources to invest 

in forest management. Comparisons of forest type dynamics among owners reflect 

differences in land management objectives and indicate the differential influence of 

natural and human-caused management forces. 

We modeled forest type transitions based on analysis of data from remeasured 

survey plots maintained by the USDA Forest Service FIA units (e.g., Griffith and 

Alerich 1996). Appendix 1 describes the data and methods used to model the area 

changes in forest cover types. Methods used in this study are extensions of earlier 

work for the 1989 RPA assessment (Alig 1985; Alig and Wear 1992; Alig and Wyant 

1985; Alig et al. 1990a; USDA Forest Service 1988, 1989). Since the 1989 assessment, additional forest cover data have been collected, and projection models have 

been refined. In general, forest cover projections have progressed from an expertopinion basis to systematic empirically based models, as described in appendix 1. 

Recent data for forest land and timberland are summarized by Smith et al. (2001) 

and also are provided at http://fia.fs.fed.us/.

Projections of forest type areas are designed to support broad-scale and longterm projections of overall land-base conditions and associated elements of forest 

ecosystems. An example of linkage to other RPA assessment modeling is interactions with models used in the RPA timber assessment (Haynes 2003). The RPA 

timber assessment’s analysis of the timber situation in the United States, 1952 to 

Area changes for forest 

cover types on private 

timberland result 

from afforestation, 

deforestation, shifts 

among forest cover 

types on retained 

timberland, and sales 

or exchanges of land 

among ownership 

groups.
4

General Technical Report PNW-GTR-613

2050 (Haynes 2003), was the fifth in a series of USDA Forest Service indepth 

analyses of the status and trends of the Nation’s timber resources. The forest 

cover model provides projections of major forest cover areas by region and period, 

and the timber assessment model feeds back timber harvest amounts and stumpage prices that are used in the forest cover modeling. Current policies are held 

constant so that we can examine where the current policy trajectory would lead, 

consistent with the approach in other parts of the RPA assessment. Both the forest 

cover modeling and other timber assessment modeling rely in part on FIA data. 

The timber situation report looks at 50 years of historical FIA data, and projects 

50 years into the future. The forest cover modeling also provides projections used 

in other modeling in RPA assessments that addresses an array of resources, including outdoor recreation, fish, wildlife, wilderness, water, range, minerals, and 

urban forests; however, the primary modeling feedbacks affecting forest cover 

projections are with the timber portion of the RPA assessment, especially that 

involving timber harvest, as discussed in this report.

Changes in areas among forest cover types affect a wide range of forestbased goods and services. Examples include wildlife habitat, forest carbon, 

scenic amenities, and recreation. Such area changes also affect both the nature 

and volume of timber available from forests. For example, decreases in timber 

production can occur when commercial species are replaced by noncommercial 

species. A major consideration in our modeling is that area change projections by 

forest management type were based on assumptions about the probability that a 

particular acre will receive a certain type of management and the associated probabilities that an acre so managed will remain in the same forest type or will make 

the transition to other forest types. 

We next discuss the forest cover situation and give projections of area changes 

for forest cover types on private timberland by RPA region. We then provide a 

national overview of the projections, drawing upon the RPA assessment findings 

and interactions with other RPA modeling. 

Projections of area 

changes for forest 

cover types on 

private timberland are 

based on analysis of 

historical relationships 

and assumptions about 

factors affecting future 

supply and demand 

conditions, such as 

population growth 

and timber prices.
5

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Introduction 

The North includes 20 states in the Northeast and North Central subregions of the 

United States (fig. 1, table 1). This region extends from the Atlantic seaboard in the 

East to the farmland prairies in the Corn Belt; from the Ohio River, the Appalachian 

Highlands, and the northern Piedmont in the South to the Canadian border and the 

Great Lakes in the North. The more northern states of the region have moderately 

long, relatively severe winters. Annual precipitation is moderate and ranges from 25 

to 45 inches; often half of this precipitation comes as snow (USDA Forest Service 

1989). Short growing seasons of 100 to 140 frost-free days limit agricultural production. 

Much of this area has been glaciated, and glacial landforms are common. Soils 

are generally well suited for forests, which are the natural potential vegetation for 

most of the region; however, high water tables are common in some areas, creating extensive wetland systems. Because much of the North, except for the prairie 

fringes in the western portions of Iowa, Minnesota, and Missouri, was originally 

forested, it tends to revert back to forest if disturbed and then allowed to stand idle. 

In contrast to forests in the West, northern forests tend to have diverse mixtures of 

tree species, and species mix can differ with climate, soils, and glacial history. 

About two-fifths of the North is in forest use, a dominant land use (64 percent) 

in the Northeast in contrast to that for the North Central region (28 percent). The 

Northeast is one of the most heavily urbanized parts of the United States, with 12 

percent of land classified as “urban” (USDA NRCS 2001). However, states in the 

Northeast are quite heterogeneous with regard to land use patterns. For example,

88 percent of Maine’s land is in forest cover and only 3 percent in cropland, whereas 

Delaware has 31 percent forest cover and 39 percent cropland. Just 2 percent of West 

Virginia is classified as urban, whereas 35 percent of New Jersey is so classified. 

The North Central subregion has less of its land base classified as urban (7 

percent) compared to the Northeast (12 percent). The North Central’s Corn Belt 

contains the states of Illinois, Indiana, and Iowa. Cropland is the dominant land use 

in this subregion. As in the Northeast, the states of the North Central subregion are 

quite heterogeneous with regard to land use patterns. For example, Iowa has 80 percent of its land base in cropland and 5 percent in forest. In contrast, Michigan has 24 

percent in cropland and 48 percent in forest.

The majority of the forest lands in the North remain in private ownership, most 

as timberland (figs. 2 and 3). Private owners possess 80 percent of the region’s 

timberland, including most of the region’s more productive forest land (fig. 4). The 

nonindustrial private forest (NIPF) ownership is by far the largest, controlling 71 

percent of timberland in the North (Smith et al. 2001). 

Chapter 1: North

Forests cover 64 

percent of the 

Northeast and 28 

percent of the North 

Central subregion 

and most of this 

land is controlled by 

nonindustrial private 

forest ownerships.
6

General Technical Report PNW-GTR-613

Figure 2—Area of U.S. forest land and timberland by region, 1997 (Smith et al. 2001).

Figure 3—Area of public and private timberland by region, 1997 (Smith et al. 2001).

250

200

150

100

50

0

Forest land and timberland area (million acres)

Forest land

Timberland

North South Rocky 

Mountains

Pacific 

Coast

Region

200

180

160

140

120

100

80

60

40

20

0

Timberland area (million acres)

Public timberland

Private timberland

North South Rocky 

Mountains

Pacific 

Coast

Region
7

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 4—Area of high-productivity forest land by region, 1997, in productivity classes equal to or 

greater than 85 cubic feet per acre per year (Smith et al. 2001).

90

80

70

60

50

40

30

20

10

0

Forest land area (million acres)

Public

Private

North South Rocky 

Mountains

Pacific 

Coast

Region

The entire region has been heavily disturbed by human activities, with many 

existing forest stands dating from the late 1800s. Human and natural disturbances 

exert great influences on forest cover. Historically, fires and windstorms have 

caused the greatest natural disturbances. Since colonization by European-Americans, human disturbances have escalated in importance. The impetus for these 

disturbances has evolved from subsistence to profit to conservation and preservation, and the effects have differed based on specific objectives (Stearns 1997, 

Vasievich and Webster 1997). 

Forests containing white pine (Pinus strobus L.) were the first areas to be 

logged (often high graded) in response to the country’s increasing lumber demands. 

Eastern hemlock (Tsuga canadensis (L.) Carr.) was then harvested for tanneries, 

and hardwoods for specialty markets were next to be used. In more recent times, 

aspen (Populus tremuloides Mich X.) has surpassed many other species in commercial importance because of its utility in pulp and particleboard production. In 

addition to commercial uses, the forests of the North have continued to provide 

important amenities including recreational opportunities.

Forest Cover Situation

Hardwood forest types (e.g., oak-hickory) comprise about 80 percent of total forest 

area in the North (fig. 5), with about equal percentages in both the Northeast and 

Between 1953 and 

1997, total area of 

hardwood forest types 

in the North increased 

notably compared to 

softwood area, with 

the area of the maplebeech-birch forest type 

more than doubling.
8

General Technical Report PNW-GTR-613

716

17,449

10,992 7,042

17,842

10,651

52,062 53,565

White-red-jack pine

Spruce-fir

Oak-hickory

Elm-ash-cottonwood

Maple-beech-birch

Aspen-birch

Other forest types

Nonstocked

Figure 5—Area of forest land (thousand acres) by forest cover type in the North region, 1997 (Smith 

et al. 2001).

60

50

40

30

20

10

0

1953 1963 1977 1987 1997

Year

Timberland area (million acres)

Pines

Spruce-fir

Oak-pine

Oak-hickory

Lowland hardwoods

Maple-beech-birch

Aspen-birch

Figure 6—Area trends for major forest cover types on timberland in the North region, 1953 to 1997 (Smith et al. 2001).
9

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Table 2—Area of total timberland in the United States, by softwood and 

hardwood type groupings and region, 1953–97 

Region 1953 1963 1977 1987 1997

- - - - - - - - - - - - - - - - Thousand acres - - - - - - - - - - - - - - - -

Softwoods:

 North 31,396 31,939 31,298 31,745 27,960

 South 79,059 77,557 64,573 62,871 63,504

 Rocky Mountains 60,997 61,164 55,428 56,035 62,114

 Pacific West 58,318 58,035 51,819 50,878 50,369

 Total 229,770 228,695 203,118 201,529 203,947

Hardwoods:

 North 116,247 119,970 117,394 120,798 131,071

 South 118,141 124,885 129,823 130,798 136,064

 Rocky Mountains 5,600 5,756 4,745 5,105 8,796

 Pacific West 4,773 4,734 7,566 6,849 8,248

 Total 244,761 255,345 259,528 263,550 284,179

Nonstocked timberland:

 North 6,633 4,698 4,754 1,876 404

 South 7,346 6,261 5,234 3,599 1,431

 Rocky Mountains 3,241 3,280 2,556 1,576 108

 Pacific West 4,370 3,242 3,782 814 1,203

 Total 21,590 17,481 16,326 7,865 3,146

Total 496,121 501,521 478,972 472,944 491,272

Note: Represents total timberland across all ownerships. Does not include Alaska. Data are from 

Smith et al. (2001) and are subject to revision. Some row and column totals may not sum exactly due 

to rounding errors and compilation errors.

North Central subregions. Between 1953 and 1997, total area of hardwood forest 

types in the North increased notably compared to softwood area (fig. 6). In particular, the area of maple-beech-birch more than doubled, adding 27 million acres; 

it became the most common type, covering 31 percent of the region’s timberland 

in 1997 (Smith et al. 2001). The large area of oak-hickory also increased, but at a 

markedly slower rate than for the climax type of maple-beech-birch. The oak-hickory and maple-beech-birch forest cover types cover the largest areas in the North, 

combining to represent 62 percent or 106 million acres of unreserved forest land 

(Smith et al. 2001). Generally, the oak-hickory ecosystem grows in a wide band 

along the southern portion of the area and joins the maple-beech-birch ecosystem 

to the north (USDA Forest Service 1989). 

Area of the mixed type of oak-pine more than tripled between 1953 and 1997, 

but still only covers less than 3 percent of the region’s timberland (fig. 6). Oak-pine 

is a relatively “unstable” forest type, and slight changes in stand stocking can result 

in reclassification of the forest type. Increases in total timberland area in the North 
10

General Technical Report PNW-GTR-613

since 1977 (table 2) have contributed to the expansion of the oak-pine type, where 

member species are early to midsuccessional. 

The largest area reductions between 1953 and 1997 were for elm-ash-cottonwood, 9.7 million acres, and for aspen-birch, 7.8 million acres. The largest area 

increase for a softwood cover type was the 1.6-million-acre increase for the whitered-jack pine type. The largest area reduction for a softwood cover type was the 

3.7-million-acre decline for the spruce-fir type. 

For the most recent historical interval between 1987 and 1997, the North gained 

more than 5 million acres of timberland, mostly represented now by hardwood 

types. Pioneer species (e.g., black cherry [Prunus serotina Ehrh.] and white ash 

[Fraxinus Americana L.]) naturally regenerated onto abandoned agricultural lands, 

including former diary farmland and some old-field succession (fig. 7). Other acres 

were afforested actively with pines, part of the white-red-jack pine type. 

Figure 7—Reversion of former agricultural land (e.g., pastureland) to forest has been significant 

in the North region over the last several decades.

At the same time, other acres were transitioning among seral stages. Between 

1987 and 1997, the largest net gains were for the maple-beech-birch (7.3 million 

acres) and oak-hickory (3.8 million acres) types. Species composition and the successional role of species can differ geographically. For example, most oaks are considered early to midsuccessional species, and although oaks may have an increasing 

importance going from east to west in the oak-hickory type, much development 

of oak forests has occurred through a variety of land use and land cover pathways 

and disturbance patterns. Continuing and overlapping disturbances in the range of 

The largest area 

reductions between 

1953 and 1997 in the 

North were for elmash-cottonwood and 

aspen-birch.
11

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

oak-hickory forest arise from the frequently high value of the land for agriculture 

and for developed uses of land near cities. Over the mosaic of the landscape, there 

can be overlapping disturbance patterns, and seral-stage distribution can be altered 

markedly by human activities. 

The North Central subregion has a slightly higher hardwood cover percentage 

than does the Northeast. Between 1987 and 1997, the total percentage of hardwood 

cover types grew slightly in the North. Hardwood types are often the climax species in the North, and successional forces led to the increasing hardwood percentage. Timber harvest in the North, as a potential major disturbance, has not been as 

prevalent as in other regions, such as the South (Haynes 2003), although exceptions 

may be northern Maine and parts of the Lake States. This has led to increasingly 

older forest stands in some cases and a slower regeneration rate when contrasted to 

the forest cover situation in the South, for example. 

The Lake States of Michigan, Minnesota, and Wisconsin (a subset of the North 

Central subregion) provided roughly two-fifths of 1996 timber harvests in the North 

(Smith et al. 2001), with most coming from private timberlands. In 1997, maplebeech-birch and aspen-birch were the most abundant forest cover types on private 

timberlands in the Lake States. Aspen-birch covered more than 7 million acres and 

about 90 percent was located on NIPF lands. For forest industry, the three forest 

types with the largest areas are maple-beech-birch, 44 percent; spruce-fir, 28 percent; and aspen-birch, 11 percent (Smith et al. 2001). 

In general over the historical period, greater absolute and relative changes in 

the Lake States have been on NIPF timberlands rather than on forest industry timberlands. The NIPF ownership also has been the most affected by land use changes. 

The changing nature of agriculture and conversions of forest land to developed uses 

have been major factors in forest area changes in the North (Mauldin et al. 1999a, 

1999b; Plantinga et al. 1999). Some Northern states have had an increase in forest 

area in recent decades, with most of the increase linked to a decrease in agricultural 

area, particularly in the dairy sector (Mauldin et al. 1999a, 1999b). Pastureland 

area in all three Lake States has declined since 1953, with a shift from pasturing 

to intensive cropping as the primary method of growing feed for livestock. As in 

the Northeast, many abandoned pasturelands have reverted naturally to forests. In 

the North, the largest gain in forest cover by type has been the 8-million-acre gain 

in maple-beech-birch between 1987 and 1997 (Smith et al. 2001), with the gain 

primarily on NIPF timberlands. 

In the Northeast, maple-beech-birch and oak-hickory were the most abundant 

forest covers in 1997. Maple-beech-birch covered more than 10 million acres of 

land, 86 percent of that owned by NIPF owners. For the NIPF ownership in the 
12

General Technical Report PNW-GTR-613

Northeast, the three forest types with the largest areas are oak-hickory, 36 percent; 

maple-beech-birch, 32 percent; and aspen-birch, 8 percent. 

Maine provided more than one-third of the Northeast’s timber harvest in 1996 

(Smith et al. 2001). Slightly more than one-half of 1996 timber removals in Maine 

were softwoods, slightly higher proportionately than timberland area in softwood 

cover types (Griffith and Alerich 1996). Spruce-fir is the main softwood type in 

Maine, covering about 35 percent of the state’s timberland. The northern hardwoods 

type replaced the spruce-fir type as the most common forest cover type, as its 6 

million acres cover 38 percent of Maine’s timberland (Griffith and Alerich 1996). 

A major factor has been the transitions of spruce-fir stands to northern hardwoods 

following harvest of the spruce-fir type. These changes have almost all been on 

private timberlands, which represent 96 percent of the Maine total and which have 

seen significant ownership shifts in recent decades (Plantinga et al. 1999). In contrast to earlier trends, since the 1980s, NIPF timberland area in Maine has increased 

while forest industry timberland area has declined. 

Projections

Dominant projected changes for forest cover on private timberland in the North 

are decreases in the areas of spruce-fir and aspen-birch and increases in the areas 

of lowland hardwoods (including red maple-dominated forest types, fig. 8) and 

maple-beech-birch. Projected area changes for hardwood forest cover types are 

largely based on a continuation of recent trends, whereas softwood cover types 

are projected to diverge somewhat from historical trends. Overall, the trend is toward a higher percentage in hardwood types relative to softwood types (table 3).

The projected changes vary 

across the region, with the losses 

of spruce-fir and aspen-birch in the 

Northeast (e.g., Maine, Vermont, 

New Hampshire, and New York) 

and the Lake States (i.e., Michigan, Minnesota, and Wisconsin), 

respectively (figs. 9–12). Most of 

the changes are projected for the 

NIPF ownership, which contains a 

large majority of the timberland in 

the region. Most of the changes on 

forest industry lands are projected Figure 8—Area of red maple has increased significantly in parts of the Northeast subregion in recent 

decades. 

Dominant projected 

changes for forest 

cover in the North 

are decreases in the 

areas of spruce-fir 

and aspen-birch and 

increases in the areas 

of lowland hardwoods 

and maple-beechbirch.

©Kenneth M. Gale, www.forestryimages.org
13

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Table 3—Projected area of private timberland in the United States by softwood and hardwood 

type groupings by region, 1997 to 2050

Timberland type and region 1997 2010 2020 2030 2040 2050

- - - - - - - - - - - - - - - - - - - - Thousand acres - - - - - - - - - - - - - - - - - - - -

Softwoods:

 North and Rocky Mountains 36,363 35,190 34,354 33,544 32,787 32,209

 South 56,105 63,744 68,014 70,990 72,462 73,103

 Pacific Coast 18,613 18,427 18,224 18,053 17,929 17,871

 Total softwood area 111,081 117,361 120,592 122,587 123,178 123,183

Hardwoods:

 North and Rocky Mountains 112,183 113,657 113,049 111,469 109,399 107,690

 South 122,635 114,708 109,773 106,407 104,214 102,830

 Pacific Coast 5,806 5,542 5,403 5,290 5,200 5,140

 Total hardwood area 240,624 233,907 228,225 223,166 218,813 215,660

Total private timberland area 351,705 351,268 348,817 345,753 341,991 338,843

Note: Does not include nonstocked timberland. Some column totals are subject to rounding errors and compilation errors. Timberland area (million acres)

12

10

8

6

4

2

0

1997 2000 2010 2020 2030 2040 2050

Year

Aspen-birch

Maple-beech-birch

Elm-ash-red maple

Oak-hickory

Oak-pine

Pine-oak-gum-cypress

Spruce-fir

White-red-jack pine

Figure 9—Projected area changes for forest cover types on forest industry timberlands in the Northeast, 1997 to 2050. 

decreases, with the exception of the area of white-red-jack pine, which is projected 

to increase by nearly 40 percent over the next 50 years. 

Within the region, the forests of the Lake States are expected to continue to provide a substantial proportion of the region’s timber harvest and have the larger relative changes in areas of forest covers. The projected trends of the hardwood forest 
14

General Technical Report PNW-GTR-613 Timberland area (million acres)

70

60

50

40

30

20

10

0

1997 2000 2010 2020 2030 2040 2050

Year

Aspen-birch

Maple-beech-birch

Elm-ash-red maple

Oak-hickory

Oak-pine

Pine-oak-gum-cypress

Spruce-fir

White-red-jack pine

Timberland area (million acres)

5

4

3

2

1

0

1997 2000 2010 2020 2030 2040 2050

Year

Aspen-birch

Maple-beech-birch

Elm-ash-cottonwood

Oak-hickory

Spruce-fir

White-red-jack pine

Figure 10—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Northeast, 1997 to 2050. 

Figure 11—Projected area changes for forest cover types on forest industry timberlands in the Lake States, 1997 to 2050. 
15

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

covers are largely consistent with historical trends, whereas the projected softwood 

trends are somewhat divergent from historical trends. On private timberlands in 

the Lake States, the changes in the forest cover areas are projected to range from 

decreases of 19 percent to increases of 17 percent between 1997 and 2050. 

On NIPF timberlands in the Lake States, maple-beech-birch is projected to 

increase by approximately 1.7 million acres, a 19-percent increase (fig. 12). Most 

of this increase is from oak-hickory, aspen-birch, and elm-ash-cottonwood forest 

covers. Elm-ash-cottonwood is the only other NIPF forest cover projected to have a 

net increase (98 thousand acres, 3-percent increase). Of the decreasing forest covers, white-red-jack pine and spruce-fir forest covers are projected to have the largest 

relative losses, 22 and 23 percent, respectively, but oak-hickory and aspen-birch 

also are projected to have substantial area decreases.

Notable projected changes are an increase in the area of elm-ash-red maple 

forests in the Northeast and decreases in the areas of spruce-fir in the Northeast 

and aspen-birch in the Lake States. The increase in elm-ash-red maple is primarily 

due to the large influx of red maple in the region. The projected decrease in sprucefir is related to the large areas infected by insect pests (e.g., spruce budworm 

[Choristoneura occidentalis Freeman]) that were recorded in the data used to develop the projection model. The loss of aspen-birch has largely been the result 

of insufficient regeneration opportunities for this early successional forest type. Timberland area (million acres)

30

25

20

15

10

5

0

1997 2000 2010 2020 2030 2040 2050

Year

Aspen-birch

Maple-beech-birch

Elm-ash-cottonwood

Oak-hickory

Spruce-fir

White-red-jack pine

Figure 12—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Lake States, 1997 to 2050. 

In the Northeast, 

the area of elm-ashred maple forest is 

projected to increase.
16

General Technical Report PNW-GTR-613

Timber harvests on forest industry and NIPF lands in the North have been at or 

below timber growth for some time (Haynes 2003), causing timber inventories to 

be stable or rising. Timber harvests are projected to increase on NIPF timberlands, 

driven by expansion in both sawtimber and pulpwood uses. At the same time, NIPF 

timberland owners in the region are increasingly motivated by objectives other than 

timber harvest and revenue generation in managing their lands. A disinclination to 

harvest timber is related in part to fractionation of the timberland base (Alig et al. 

2000b), growing diversity of types of owners (King and Butler, in press), and to 

the declining importance of timber harvest revenues in the income of forest landowners. As a result, NIPF hardwood inventory will continue to rise. 

On forest industry timberlands in the Lake States, the white-red-jack pine 

forest cover is projected to have the greatest relative and absolute changes with a 

projected increase of 314,000 acres or 120 percent between 1997 and 2050 (fig. 11). 

Maple-beech-birch is the only other forest cover to have a projected increase, but 

the increase is only projected to be 1 percent or 17 thousand acres. Of the decreasing forest covers, aspen-birch is projected to have the most substantial decrease 

with a loss of 193,000 acres or 26 percent. Oak-hickory is also projected to have a 

rather substantial decrease with a projected loss of 19 percent of its 1997 area or 

73,000 acres.

The maple-beech-birch forest cover is projected to have the largest area increase in the Lake States. This increase is on NIPF lands and is the result of a 

combination of transitions following both final and partial harvests and natural 

succession. Aspen-birch, elm-ash-cottonwood, and oak-hickory have only moderate 

partial timber harvest probabilities; approximately 1 percent of each of these forest 

covers is projected to be partially harvested. However, they have relatively high 

propensities, 25 to 30 percent, to transition to maple-beech-birch following these 

partial timber harvests. At least part of this high-transition propensity is due to 

maple-beech-birch being a relatively diverse forest cover compared to the other 

forest covers, and partial timber harvests will release the more shade-tolerant 

species that are characteristic of this forest type. Maple-beech-birch is a later 

successional forest type, consistent with higher probabilities of transition to this 

cover type if no harvest occurs over a remeasurement period.

Final harvests of timber in the Lake States lead to the highest probabilities for 

transitions among forest cover types. Following a final harvest on private lands, 

the resultant forest cover is expected to be the same as the previous forest cover in 

most circumstances (55 percent on average), but this differs greatly among forests 

types and owners. On forest industry lands, maple-beech-birch, spruce-fir, elm-ashcottonwood, and white-red-jack pine forest covers are more likely to transition to 

The maple-beechbirch forest cover is 

projected to have the 

largest area increase in 

the Lake States.
17

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

a different forest cover following a final harvest than to stay the same forest cover. 

Aspen-birch and oak-hickory are the forest covers that are most likely to result from 

a transition. On NIPF lands, white-red-jack pine, oak-hickory, and spruce-fir forest 

covers are more likely to transition to other forest covers than to remain the same 

forest cover following a final harvest. Aspen-birch, maple-beech-birch, and oakhickory are the most common forest types to result from transitions on NIPF lands. 

On average, 78 percent of the private timberland in the Lake States that received partial timber harvests were projected to remain the same forest type following this management activity, with this average value being slightly lower for NIPF 

lands (75 percent) than for forest industry lands (81 percent). Aspen-birch, elm-ashcottonwood, and oak-hickory have the highest propensities to transition on NIPF 

lands, whereas aspen-birch and spruce-fir have the highest transition probabilities 

on the forest industry lands. Elm-ash-cottonwood and aspen-birch were expected as 

the most common fates of partially harvested acres on both NIPF and forest industry timberlands that transition among forest cover types. If no harvests occur, the 

probabilities of transitions are very low within the 13-year time step. On forest industry lands, an average of 2 percent of the forest covers are expected to transition 

to another forest cover in the absence of harvest activities; these values ranged from 

1 to 3 percent, disregarding the nonstocked lands. An average of 1 percent of the 

NIPF timberlands would transition without harvests, with a range of 1 to 2 percent. 

Elm-ash-cottonwood and aspen-birch have the highest propensities to transition to 

another forest cover.

One resource issue identified when considering the future outlook in a Lake 

States forest resource study (Vasievich and Webster 1997) is the declining available 

aspen resource. This relates to investments in processing capacity in the region. 

However, regional capacity growth for aspen-based industries like oriented strand 

board has slowed in recent years (Ince 2000). Over the entire timberland base in the 

Lake States, timber growth exceeds harvest by a significant amount, and although 

the amount of harvest of timber has increased over the past 40 years, forest growth 

has increased more, leading to more timber inventory (Smith et al. 2001). Harvest is 

projected to remain below growth on NIPF timberlands in the North, and industrial 

timber harvest at or just below growth. The overall area of aspen-birch in the North 

declined from 24.6 million acres in 1953 to 16.8 million acres in 1997 (Smith et al. 

2001). In addition, as part of the array of forces at work, NIPF owners are increasingly motivated by objectives other than timber production and harvest. Population 

growth has contributed to an increasing number of second homes, especially around 

lakes and other water areas, which has affected the availability of some aspen-birch 

timberland for timber harvests. 

The total area of 

aspen-birch in the 

Lake States decreased 

by 7.8 million acres 

between 1953 and 1997.
18

General Technical Report PNW-GTR-613

In the Northeast, the largest changes in the areas of forest covers on private 

timberlands are projected for NIPF timberlands (fig. 10); however, forest industry’s 

lands (fig. 9) have larger projected changes relative to the total amount of timberland in the respective ownership categories. On NIPF timberlands, the largest forest 

cover changes are projected losses of maple-beech-birch and spruce-fir forest covers 

and projected increases in the areas of the aspen-birch and oak-pine forest covers. 

Maple-beech-birch is projected to lose almost 1.7 million acres of land by 2050 (11 

percent of the initial forest cover area), whereas spruce-fir is projected to decrease 

by almost 1.3 million acres (34 percent) within the same period. Aspen-birch and 

oak-pine are projected to increase by 0.7 (34 percent) and 0.4 (24 percent) million 

acres, respectively. 

On the forest industry lands in the Northeast, the largest relative change is a 

70-percent increase in the area of white-red-jack pine, an increase of approximately 

0.2 million acres by 2050. All other forest industry forest covers are projected to 

decrease, especially the oak-hickory and maple-beech-birch forest covers with 

losses of 0.6 (15 percent) and 0.3 (6 percent) million acres, respectively. 

Summary, North Region

Soils are generally well suited for forests, which are the natural potential vegetation 

for most of the region. Northern forests tend to have relatively diverse mixtures of 

tree species. The region has been heavily disturbed by human activities. Most of 

the forest is privately owned, and the diversity of landowner objectives can promote 

species and seral diversity. Hardwood forest types dominate the region’s forest land. 

The oak-hickory and maple-beech-birch forest cover types are the largest in the 

North, combining to represent 62 percent or 106 million acres of unreserved forest 

land. Between 1953 and 1997, the area of maple-beech-birch more than doubled, 

adding 27 million acres. The largest projected changes in forest cover areas are 

decreases for the spruce-fir and aspen-birch types and increases in the areas of 

lowland hardwoods (including red maple-dominated forest types) and maple-beechbirch. Projected area changes for hardwood forest cover types are largely based 

on a continuation of recent trends, whereas softwood cover types are projected 

to diverge somewhat from historical trends. Timber harvest is important regarding projected changes in forest cover type areas, and levels of timber harvest will 

allow the aggregate NIPF hardwood inventory to continue to rise; industrial timber 

harvest will be equal to or slightly less than timber growth, and inventory will rise 

slightly over the projection.
19

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Introduction

The South includes 13 states of the Southeastern and South Central subregions 

(fig. 1, table 1). The area extends from Virginia southward and westward along the 

Atlantic and Gulf seaboards to Texas and includes the interior states of Arkansas, 

Kentucky, Oklahoma, and Tennessee. This region is characterized by a variety 

of climatic and edaphic conditions that relate to its diverse physiography (USDA 

Forest Service 1989). The South covers portions of five physiographic divisions: the 

Atlantic Plain, the Appalachian Highlands, the Interior Highlands and Piedmont, 

Delta, and the Interior Plains. Elevations range from the coastal flats to mountains 

of the Blue Ridge province that have peaks over 6,000 feet. The climate ranges from 

subtropical with rainfall averaging 40 to 60 inches annually in parts of the coastal 

plains to more arid conditions in parts of the Interior Plains. 

The South is heavily forested from Virginia to the forest’s limit in eastern 

Texas and Oklahoma. Forest land totals 214 million acres or 40 percent of the 

region’s land area, with five states being more than 60 percent forested. The Southeast is 60 percent forested, whereas the South Central subregion is only 32 percent 

forested owing in large part to the large areas of range and scrubland in Texas and 

Oklahoma. The fraction of forest land that is classified as timberland has remained 

fairly constant at about 96 percent over the past half century, reflecting the inherent 

productivity of the forest-land base and the general availability of forest land 

for timber operations (fig. 4). 

The South has some of the most commercially important timber species, such 

as loblolly pine (Pinus taeda L.), and forestry and forest products are important 

industries in the region. Human disturbances are a dominant force affecting forest 

structure and composition (Alig and Wyant 1985, Wyant et al. 1991). The largest 

human disturbance is timber management, which includes commercial timber 

harvests along with precommercial thinnings, mechanical and chemical site preparations, planting of seedlings, prescribed burning, fertilization, fire protection, 

and herbicide and pesticide applications (Dubois et al. 1999). In recent years, the 

South has harvested more timber than any other country (Wear and Greis 2002). 

The region also is looked to as a source of more timber in the future, including an 

increasing share from relatively fast-growing pine plantations (Alig et al. 2002b, 

Haynes 2003). 

Private timberlands compose around 90 percent of the U.S. South timberland 

(Smith et al. 2001). The behavior of the groups and individuals who own these lands 

has led to a substantial expansion of pine plantation area in the U.S. South (Kline et 

al. 2002). Within its relatively large timberland base, the South contains two-thirds 

of the Nation’s tree plantations. The South is the leading tree planting area in the 

Chapter 2: South

Forest land totals 214 

million acres or 40 

percent of the South’s 

land area.
20

General Technical Report PNW-GTR-613

United States for a number of reasons, including a favorable climate (long growing 

season and generally abundant precipitation), historically good timber markets and 

the heavy concentration of forest industry in the region, and comparatively less competition for land from some major agricultural field crops (e.g., corn). The economic 

attractiveness of tree planting in the South was enhanced by reduced timber harvests 

on federal lands concentrated in the West. Agriculture is an important and diversified sector of the regional economy, but it is based largely on fruits and vegetables, 

rice, tobacco, cotton, poultry, hogs, and cattle, and is not a significant producer of 

major field crops such as corn and wheat. 

Forest Cover Situation 

The region’s timberland area is still dominated by hardwood forest types (Smith 

et al. 2001) (fig. 13, table 2). More than one-half of the region’s timberland has hardwood cover. Based on the broad forest cover types surveyed by the USDA Forest 

Service Forest Inventory and Analysis (FIA) unit, the upland hardwood type covers 

the most area (e.g., oak-hickory), followed by planted pine, natural pine, lowland 

hardwoods (e.g., elm-ash-cottonwood), and oak-pine forest types. 

Upland hardwood is the dominant forest type on nonindustrial private forest 

(NIPF) timberlands, whereas planted pine is the dominant forest type on forest 

industry timberlands. In 1997, upland hardwood accounted for 68 million acres of 

timberland or 38 percent of total southern private timberland (fig. 14), with over 80 

percent of this area on NIPF timberlands. 

Although the area of pine plantations has increased substantially in the Southern 

United States, only about 14 percent of the total southern private timberland is currently covered by pine plantations (figs. 15 and 16). Across the South, a proportionately larger amount of forest industry timberland (39 percent) is planted compared 

to NIPF timberland planted (10 percent). Planted pine is the dominant forest type on 

forest industry timberlands. Forest industry owned over half of the 30 million acres 

of planted pine located in the U.S. South in 1997, although NIPF owners possess 

about four times as much timberland in total. Many of the plantations are found in 

the Coastal Plain, the geographic area that stretches inland along the coast from 

Virginia to Texas, with gentle slopes and little local relief. 

In addition to the 30 million acres of planted pine, the South has about 6 million 

acres of plantations in other forest types (e.g., oak-pine). Many of these represent 

original pine plantations that later reverted to other types owing to natural seeding 

in and resprouting of hardwoods. Approximately equal amounts of such planted 

nonpine types occur on forest industry and NIPF timberlands. 

Upland hardwood is 

the dominant forest 

type on nonindustrial 

private timberlands in 

the South and planted 

pine is the dominant 

forest type on forest 

industry lands. 

Fourteen percent 

of southern private 

timberland is currently 

covered by pine 

plantations.
21

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

64,008

30,106

79,347

31,827

4,824

2,359

Conifers

Oak-pine

Upland hardwoods

Lowland hardwoods

Other forest types

Nonstocked

Figure 13—Area of forest land (thousand acres) by forest cover type in the South region, 1997 (Smith 

et al. 2001).

Figure 14—The 1997 distribution of upland hardwood forest type on private timberland in the South region. White portions of the map 

have no significant upland hardwood area.
22

General Technical Report PNW-GTR-613

Figure 15—Map of the 1997 distribution of pine plantations on private timberland in the South region. White portions of the map have 

no significant pine plantation area.

Figure 16—Area of pine plantations in the South region increased more than tenfold from 1953 to 

1997. 
23

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

The silvicultural system and the amount of capital invested in stand establishment are major factors influencing forest type dynamics in the South. These factors 

are particularly important for pine dynamics because “pines need help to regenerate” (Knight 1973), and regeneration establishment success can differ markedly by 

ownership (McWilliams and Moulton 1991). Knight (1978) reported that in many 

areas, hardwoods replaced pines on about half of the area harvested. Between 1975 

and 1985, clearcut silvicultural systems were used to harvest two-thirds of forest 

industry’s pine stands and about one-third of NIPF pine stands; the remainder of 

the harvested stands was harvested with partial harvest silvicultural systems. The 

specific prescriptions also differed between ownerships. For example, 63 percent of 

the clearcuts on NIPF private lands left significant amounts of low-value trees, often 

hardwoods, which would significantly hinder the ability of a stand to commercially 

regenerate (McWilliams and Moulton 1991). This has led to historically low rates 

of pine stands regenerating as pine stands following human disturbances, although 

the percentage of harvested stands regenerating as pine has been increasing (Alig 

1985, Birdsey et al. 1981, Boyce et al. 1975, McWilliams and Moulton 1991) and the 

potential for further improvement appears to be substantial. 

Between 1953 and 1997, the South had some relatively large area changes for 

forest types (fig. 17). The largest changes in forest type areas have been the decrease of naturally regenerated pine, the increase of planted pine, and the increase 

of upland hardwood. Naturally regenerated pine lost a total of 59 percent of its area 

between 1952 and 1997, whereas planted pine increased eighteenfold. All ownerships had marked gains in planted pine, whereas most of the loss of natural pine has 

been on NIPF timberlands. The area of upland hardwood has been steadily increasing, especially on other private timberlands. The area of lowland hardwood has 

been steadily decreasing, especially on NIPF timberlands. The area of oak-pine has 

remained relatively constant at the regional level, but the Southeast has had a net 

gain and the South Central has had a net loss of oak-pine.

Another major factor affecting trends in planted pine areas has been the afforestation on NIPF lands that have been subsidized by the Conservation Reserve Program (CRP) or other planting programs (Moulton and Hernandez 1999). Georgia 

led the Nation in the amount of CRP tree planting, but the increases in timberland 

owing to that program, the spinoff of industry lands, and other factors did not offset 

losses of timberland in the Southeast owing to conversions to urban/developed 

uses and other uses. The situation in the South Central differed, in that net gains to 

timberland area were about four times as large as the loss in forest industry timberland area. These gains were due to CRP tree planting on formerly agricultural land, 

reversion of other lands to forest, and lands being reclassified out of the industry 

The largest historical 

changes in forest cover 

types have been a 

decrease in the area of 

naturally regenerated 

pine and increases in 

the areas of planted 

pine and upland 

hardwood.
24

General Technical Report PNW-GTR-613

ownership class. The trend in increased timberland area in the South Central, along 

with the larger starting size of the subregion’s timberland base, are consistent with 

the larger projected increments in planted pine area in that subregion compared to 

the Southeast. 

Changes in timber harvesting in the South include an increased number of chip 

mills. Wood chipping has always been an integral part of the process of using wood 

to make paper; however, there is a growing trend of using wood chips in other types 

of products used in building construction. Chip mills grind whole trees into chips 

for pulp, paper, and particleboard. Satellite chip mills or other wood processing 

facilities are efficient in terms of transportation, productivity, and wood utilization. 

Lower grade and younger trees can be thinned from forest land to provide chips, 

both for silvicultural practices (such as thinnings) as well as meeting other objectives such as wildlife habitat and aesthetics. 

Projections

Changes in total timberland area affect the amount of land available for each forest 

cover type. Deforestation because of growth in human population and subsequent 

expansion of urban and developed uses is the reason that Southern timberland area 

90

80

70

60

50

40

30

20

10

0

1953 1963 1977 1987 1997

Year

Timberland area (million acres)

Pines

Upland hardwoods

Lowland hardwoods

Oak-pine

Figure 17—Area trends for major forest cover types on timberland in the South region, 1953 to 1997 (Smith et al. 2001).

Planted pine area in 

the South increased by 

more than 25 million 

acres between 1952 

and 1997.
25

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

is projected to decline from about 201 million acres in 1997 to 198 million acres in 

2050, owing to losses of private timberland (Alig et al. 2003). Most of the projected 

net reduction is in the Southeast region, especially around large urban areas such 

as Atlanta. In some states, particularly in the east Gulf area of Florida and Georgia, 

where substantial increases in population and economic activity are expected, the 

drop is also fairly large. In most of the other Southern states, the projected changes 

are small, and in the South Central subregion, the aggregate area of timberland is 

projected to increase slightly (e.g., Ahn et al. 2001). 

Overall, the percentage of the timberland area in softwood types is projected 

to increase relative to that in hardwood types (table 3). However, the total area in 

hardwood types is projected to dominate that in softwood types. 

Planted Pine

Planted pine area on private lands 1 increased by more than 25 million acres between 1952 and 1997, more than a tenfold increase. The private area in pine plantations is projected to increase by about 14 million acres by 2050, approximately a 

52-percent increase (fig. 18). More than half of the additional planted pine acres are 

projected for forest industry lands (figs. 19 through 22). With management intensification on these industrial lands, many harvested natural pine, mixed-oak-pine, 

and hardwood stands are being artificially regenerated. The planted pine forest type 

accounts for nearly 60 percent of forest industry softwood area at the start of the 

projection, and increases to 75 percent (an addition of 7.6 million acres) by 2050. 

The area of planted pine is increasing across all ownerships in both regions and 

will continue to be concentrated in the Coastal Plain (fig. 23) (Alig 1985). Overall, 

most of the planted pine is projected to be gained in the South Central subregion 

(figs. 21 and 22). The South Central subregion has the majority of cropland and 

pastureland that could yield higher rates of return if planted to pine (USDA Forest 

Service 1988). 

Larger areas of planted pine are projected for forest industry than for NIPF 

owners in both the Southeast and the South Central subregion (figs. 19 through 22). 

This increase is largely a product of intensification of forest management practices 

and the increasing demand of the wood fiber processing industries in the South. 

With management intensification on industrial lands (e.g., Alig and Wear 1992, 

Alig et al. 1999, USDA Forest Service 1988), many harvested natural pine, mixedoak-pine, and hardwood stands are being artificially regenerated to pine plantations. 

1

 Additional FIA data allow the nonindustrial private forest ownership class to be separated 

into miscellaneous corporate and other private classes (see “Glossary”) in the South. 

Pine plantations in the 

South are projected to 

increase by 14 million 

acres by 2050.

Most of the planted 

pine is projected to be 

gained in the South 

Central subregion.
26

General Technical Report PNW-GTR-613 Timberland area (million acres)

16

14

12

10

8

6

4

2

0

1997 2000 2010 2020 2030 2040 2050

Year

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine

Figure 19—Projected area changes for forest cover types on forest industry timberlands in the Southeast subregion, 1997 to 2050. 

25

20

15

10

5

0

1950 1970 1990 2010 2030 2050

Plantation area (million acres)

Year

Historical Projected

Forest industry

Nonindustrial private forest

Figure 18—Area of the planted pine type on private timberland in the South region, 1952 to 1997, with projections 

to 2050.
27

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 20—Projected area changes for forest cover types on nonindustrial private timberland in the Southeast subregion, 1997 to 2050: 

(A) other private timberlands and (B) miscellaneous corporate timberlands. Timberland area (million acres)

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine

Timberland area (million acres)

14

12

10

8

6

4

2

0

1997 2000 2010 2020 2030 2040 2050

Year

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine

A

B

60

50

40

30

20

10

0

1997 2000 2010 2020 2030 2040 2050

Year
28

General Technical Report PNW-GTR-613

For the forest industry ownership, regeneration moves most future stands into 

more intensive management categories (Haynes 2003). This trend is in line with 

the traditional industrial forestry objective to more efficiently and economically 

produce timber crops. We assume that this objective will be maintained on forest 

industry lands despite projected periods of flat to declining pulpwood stumpage 

prices for several decades. Indeed, the projected market outcome reflects, in large 

part, the achievement of industrial forestry objectives (abundant supplies of fiber 

resources for decades to come), but it also reflects impacts of projected trends on 

the demand side, including decelerating paper and paperboard demands, rising 

product imports, and a period of relatively stagnant pulp mill capacity growth 

over the next decade. 

The shift in planted pine is not quite so dramatic for NIPF owners. Although 

the NIPF ownership begins the projection period with nearly as many acres of 

planted pine as industry, natural pine and oak-pine make up over three-quarters of 

NIPF softwood timberland. The NIPF owners are projected to add 5.6 million acres 

of planted pine by 2050, with two-thirds of the NIPF acres in the other softwood 

types. 

Kline et al. (2002) showed that the reasons for planting trees differed by ownership. On forest industry lands, tree planting was primarily a function of harvest 

levels, land value, and interest rates. On other private lands, harvest levels, planting 

Figure 21—Projected area changes for forest cover types on forest industry timberlands in the South Central subregion, 1997 to 2050. Timberland area (million acres)

25

20

15

10

5

0

1997 2000 2010 2020 2030 2040 2050

Year

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine

Nonindustrial private 

forest owners in the 

South are projected to 

add 5.6 million acres of 

planted pine by 2050.
29

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 22—Projected area changes for forest cover types on nonindustrial private timberland in the South Central subregion, 1997 to 

2050: (A) other private timberlands and (B) miscellaneous corporate timberlands. Timberland area (million acres)

12

10

8

6

4

2

0

1997 2000 2010 2020 2030 2040 2050

Year

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine

80

70

60

50

40

30

20

10

0

Timberland area (million acres)

1997 2000 2010 2020 2030 2040 2050

Year

Lowland hardwood

Upland hardwood

Oak-pine

Natural pine

Planted pine
30

General Technical Report PNW-GTR-613

costs, land values, and government planting programs were significant factors. 

The tree planting programs of the U.S. Department of Agriculture have resulted 

in the afforestation of millions of acres in the South by providing incentives for 

farmers to convert agricultural lands to pine plantations (Moulton 1999, Moulton 

and Hernandez 1999). Public policies will probably continue to have a major impact on forest dynamics in the South, but the specifics of these policies are a large 

uncertainty in the region’s future. Our projections assume a continuation of recent 

planting assistance policies, such that the funding for tree planting programs is 

assumed to remain constant in real dollar terms at levels in place after the historically high tree planting levels under the CRR (fig. 18). 

Differences in forest cover type trends among ownership groups result in part 

from different forest management objectives and constraints. Although the forest 

industry has timber production as its primary objective, NIPF owners may own 

their land for timber production, land speculation, recreational activities, or numerous other objectives. The fact that the forest industry has more or nearly equal areas of planted pine, even though they have a much smaller land base, is an attribute 

Figure 23—Projected distribution of pine plantations on private timberland in the South region, 2050. White portions of the map have no 

significant pine plantation area.

The projected loss 

of natural pine in the 

South is largely due to 

land use conversions 

and transitions to 

planted pine and 

upland hardwood 

following final 

harvests.
31

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

of their stronger timber management objectives and the capital resources that they 

have available for establishing and maintaining pine plantations. Expansion of NIPF 

pine plantation area is promoted not only by market incentives but also by various 

state and federal forestry incentives, and by many local cooperative arrangements 

with industry. 

The area of planted pine is now nearly equal to the area of natural pine and it 

is projected to significantly exceed the area of natural pine in the future. The projected loss of natural pine is largely due to land use conversions and transitions to 

planted pine and to upland hardwood following final harvests. These transitions 

and conversions are driven by profit maximization objectives and biological factors. In addition to direct human actions, natural succession and the suppression of 

natural disturbances (e.g., fire) contribute to the reduction of natural pine by reducing the competitiveness of the pines and thus promoting transitions of natural pine 

to upland hardwoods (e.g., Knight 1973, USDA Forest Service 1988).

The projections of forest type changes in the South for the 2000 Renewable 

Resources Planning Act (RPA) assessment are largely consistent with those in the 

South’s Fourth Forest study (USDA Forest Service 1988) and related studies (Alig 

and Wear 1992, Haynes et al. 1995). Using a common projection year of 2030, but 

projections of planted pine area in the 2000 RPA assessment are approximately 4 

percent lower than those in the study of the South’s Fourth Forest. The percentage 

difference is relatively small compared to the overall projected increase in private 

planted area of about 130 percent between now and 2030. 

Naturally Regenerated Cover Types

Shifts in management among the natural pine, oak-pine, upland hardwood, and lowland hardwood forest types, which are all considered to be naturally regenerated, 

can be seen in figures 19 through 22. All four cover types are projected to have a net 

loss of area. Transitions between planted and naturally regenerated stands involve 

significant amounts of two-way flows, including substantial numbers of harvested 

pine plantations reverting to naturally regenerated forest types.

Area of natural pine on private lands is projected to decrease by 15 percent over 

the projection period. Many exchanges occur between forest cover types owing to 

natural succession and management (e.g., regeneration method after harvest). Losses 

include an assumed continuation of trends in substantial hardwood encroachment 

after harvest of pine stands on NIPF lands, a topic that has been raised as an issue 

for several decades (e.g., Alig 1985; Knight 1973, 1985). Gains include reversions to 

timberland from abandoned agriculture land that seed in as pine in some cases, and 

some transitions from oak-pine to natural pine dominance in a stand. 

Area of natural pine 

on private lands is 

projected to decrease 

by 15 percent over the 

projection period in 

the South, with most 

of the loss being on 

nonindustrial private 

forest lands in the 

Southeast subregion.
32

General Technical Report PNW-GTR-613

The greatest loss of natural pine is projected for the Southeast subregion, 

particularly on NIPF lands (fig. 20). Some NIPF pine acres are projected to be 

converted to developed uses. This is particularly the case for the Piedmont region 

that has substantial population centers and interstate highways. The Piedmont is a 

plateau between the mountains and Coastal Plain, where many natural pine stands 

were established following periodic abandonment of cropland. Natural hardwoods 

are encroaching in many unmanaged pine stands. 

Natural pine areas are projected to decrease on forest industry lands in both 

subregions, but these losses are offset by increases on NIPF timberlands in the 

South Central subregion (fig. 22). Forest industry has a much smaller relative share 

of total timberland area in the South than NIPF owners, and this is especially true 

for ownership of naturally regenerated acres. Overall, forest cover types other than 

planted pine on industrial lands are projected to lose 38 percent of their area (8.6 

million acres) by 2050. Most of this change is not a loss of timberland, but a shift, 

or conversion, to planted pine. The greatest shift projected is a 59-percent reduction in area of upland hardwoods on forest industry timberlands (3.4 million acres). 

The natural pine type would be reduced by 35 percent (2 million acres). Significant 

shifting is projected within natural pine, however, as the area doubles in the partial 

cutting regime projected in the RPA timber assessment (Haynes 2003). Shifting to 

more intensive levels of even-age management does occur, but the movement out of 

these types masks the change. 

The largest shifts in management of the naturally regenerated forest types are 

projected for NIPF timberland. On the NIPF ownership, more than 7 million acres 

of natural pine and upland hardwoods are projected to be converted to other types 

or nonforest uses. This represents less than 6 percent of the area in cover types 

other than planted pine. The shift to managed stands outweighs the loss of area for 

timber production, as area assumed to be managed under the high timber management regime more than doubles in the RPA timber assessment projections (Haynes 

2003). 

The largest area decrease projected is for the upland hardwood type, with a 

12-million acre or 18-percent loss projected by 2050. The projection represents a 

change from long-term historical trends for the South. A combination of factors underlies the projected reduction: conversion to nontimberland land uses, conversion 

to pine plantations, and transitions to other types including oak-pine. Historically, 

a large source of upland hardwood was reversion of agricultural fields to forest, 

especially in the South Central subregion. Although some of this reversion is still 

occurring, larger amounts of land are being converted from upland hardwood to 

urban and agricultural uses and to planted pine. The projected rate of reduction in 

The upland hardwood 

forest type in the South 

is projected to lose 12 

million acres by 2050.
33

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

upland hardwood area slows as market incentives for conversion to pine plantations lessen with stable to falling softwood prices. Hardwoods will continue to 

dominate the forested landscape of the South. Hardwood forests in 2050 are projected to cover about one-half of the southern private timberland base, twice the 

amount for planted pine in the region (figs. 24 and 25).

The transition matrices for the no-harvest case show relatively low annual 

probabilities that any given forest type would transition to a different forest type. 

On average, it takes over 100 years for a forest to transition to another forest type 

in the absence of a harvest. These transitions result from natural succession, 

natural disturbances, and human disturbances other than final or partial harvests, 

such as control of competing vegetation. Oak-pine had the highest annual probability (6 percent) of transitioning to another forest type. In projections for forest 

industry lands, planted pine was the most common forest type to which oak-pine 

transitioned, whereas oak-pine on miscellaneous corporate and other private 

timberlands (see footnote 1 on page 25) transitioned to natural pine and upland 

hardwood. These transitions are a result of oak-pine being a relatively “unstable” 

forest type, and slight changes in stand stocking can result in reclassification of 

the forest type. 

The probability of a forest type transition following a partial harvest differed 

by forest type and subregion. Lowland hardwood had the highest and oak-pine 

had the lowest probabilities of remaining the same forest types following a partial harvest. The oak-pine forest type tended to transition to the upland hardwood 

forest type, whereas the other forest types tended to transition to oak-pine. The 

probabilities of forest type transitions following partial harvests were higher in the 

South Central subregion than in the Southeast.

The final-harvest forest type transition probabilities differed significantly by 

forest type, ownership, and subregion. The lowest probabilities for a forest type 

remaining in the same forest type after a final harvest were for natural pine, an average of 9 percent. The highest probabilities of forest types remaining in the same 

forest type following final harvests were for lowland hardwood and planted pine. 

Planted pine and upland hardwood were the most common fates for transitions of 

forest types after final harvest. An example of the regional and ownership differences is the probability that planted pine will remain in planted pine following a 

final harvest. The probability is much higher in the Southeast and for forest industry owners. The forest type transition matrices from AF&PA (1999) and Moffat et 

al. (1998) showed trends similar to the FIA-based matrices (also see app. 1), with 

the exception that the AF&PA and Moffat et al. matrices showed higher retention 

of planted pine and higher transition rates to planted pine.
34

General Technical Report PNW-GTR-613

Figure 25—Hardwood forest cover types cover the most timberland in the South region.

Figure 24—Projected distribution of the upland hardwood forest type on private timberland in the South region, 2050. White portions of 

the map have no significant upland hardwood area.

Final harvest transition 

probabilities differed 

significantly by forest 

type, ownership, and 

subregion.
35

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

The projection of an increasing area of lowland hardwood on NIPF private 

timberlands in the South Central may be an indication that federal and state policies 

are having their desired effects. The Swampbuster provision of the 1985 Farm Bill, 

coupled with changes in the federal tax code (Moulton and Dicks 1990) to discourage the conversion of wetlands to agricultural uses, the Wetland Reserve Program, 

the federal no-net-loss of wetlands policy, and other actions by federal and state 

governments and by conservation organizations working with landowners may be 

having the intended effect of protecting and restoring valuable forested wetlands. 

This projected increase is partially attributable to the transition of upland to lowland forest types. As this may occur at small scales and may not be a long-term 

pattern, this transition probability was set to zero, and the area of lowland hardwoods followed the historical trends. 

The area of natural pine was projected to decrease by both the South’s Fourth 

Forest study (USDA Forest Service 1988) and the 2000 RPA assessment. Natural 

pine area is affected by transitions among all five major forest cover types in the 

South (Alig et al. 1986). The relatively large amount of transitions among forest 

types, especially after final harvests, is consistent with earlier studies (e.g., Alig 

1985, Knight 1973, USDA Forest Service 1988) and timber policy analyses suggesting many opportunities to accelerate regeneration of harvested stands and increase 

forest stocking. Regeneration lags and a somewhat stochastic mixture of regenerated species may be beneficial for some wildlife species using the forests, but 

those topics and related tradeoffs are outside the scope of this particular study. The 

empirically based type transition modeling does suggest that the Southern forest is 

quite dynamic and varied in composition, in contrast to speculations about monocultures covering a large part of the region. 

Summary, South Region

In 1997, the area of private timberlands in the Southern United States was dominated by upland hardwoods, followed by planted pine, natural pine, lowland hardwoods, and oak-pine forest types. One of the largest changes in U.S. forest type 

areas over the last half century has involved pine types in the South. Area of 

planted pine has increased more than tenfold since 1950, mostly on private lands. 

Planted pine area on private lands increased by more than 25 million acres between 

1952 and 1997. Management intensification on these industrial lands is one of the 

reasons some harvested natural pine, mixed oak-pine, and hardwood stands are being artificially regenerated to pine plantations. Private landowners have responded 

to market incentives and government programs, including subsidized afforestation 

on marginal agricultural land. Timber harvest is a crucial disturbance affecting 

One of the largest 

changes in U.S. forest 

type areas has been 

the increase in planted 

pine.
36

General Technical Report PNW-GTR-613

planted pine area, as other forest types are converted to planted pine after harvest. 

The private area in pine plantations is projected to increase by about 17 million 

acres by 2050, approximately a 53-percent increase largely owing to the addition of 

pine plantations on forest industry lands. Conversely, many harvested pine plantations revert to other forest types, mainly owing to passive regeneration behavior on 

nonindustrial private timberlands. 

The area of natural pine on private lands is projected to remain constant. 

Although there are many exchanges among forest cover types owing to natural 

succession and management (e.g., regeneration method after harvest), the gains 

and losses essentially offset each other. Losses include an assumed continuation of 

trends in substantial hardwood encroachment after harvest of pine stands on NIPF 

lands, which has been raised as an issue for several decades (e.g., Alig 1985, Knight 

1973). Gains include reversions to timberland from abandoned agriculture land that 

seed in as pine in some cases, and some transitions from oak-pine to natural pine 

dominance in a stand. Natural pine areas are projected to decrease in the Southeast and on forest industry lands in both subregions, but these losses are offset by 

increases on NIPF timberlands in the South Central subregion. 

The largest projected area decrease is for the upland hardwood type, with an 

18-million-acre or 26-percent loss projected by 2050. A combination of factors underlies the projected reduction: conversion to nontimberland land uses, conversion 

to pine plantations, and transitions to other types including oak-pine. The projected 

rate of reduction in upland hardwood area slows considerably after 2010–15, as 

incentives for conversion to pine plantations lessen with stable to falling softwood 

prices. The projection represents a change from long-term historical trends for the 

South. However, hardwoods will continue to dominate the forested landscape of 

the South. Hardwood forests in 2050 are projected to cover about one-half of the 

southern private timberland base, twice the amount for planted pine in the region. 

The FIA data concerning type transitions after harvests of pine plantations further 

suggest that many plantation acres are currently reverting to naturally regenerated 

forest types, ranging from 70 percent of the final harvested plantations on NIPF 

private timberlands in the South Central subregion to 34 percent on industry timberlands in the Southeast subregion. 

The forest type dynamics of the region vary by ownership and subregion. 

Most of the planted pine is projected to be gained in the South Central subregion, 

and larger areas of planted pine are projected for the forest industry than for other 

private or miscellaneous corporate owners in both the Southeast and the South 

Central subregions. The greatest loss of natural pine is projected for the Southeast 

subregion, particularly on other private timberlands. The largest changes in the area 
37

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

of oak-pine are projected decreases on forest industry timberlands, especially in 

the South Central subregion. The total area of lowland hardwood was projected to 

remain relatively constant at the regional level, but the area of lowland hardwood 

was projected to increase on NIPF timberlands in the South Central subregion and 

decrease in all other ownership/subregion categories.
38

General Technical Report PNW-GTR-613
39

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Introduction

The Rocky Mountains region consists of the Intermountain and Great Plains subregions (fig. 1, table 1). The region covers a vast area, about 742 million acres or 

about one-third of the entire Nation and encompasses a variety of landforms with 

diverse climatic conditions. Scenic landscapes of the Intermountain subregion 

stretch from the Canadian border to the Mexican border, and from the plains westward into the mountainous states. The Great Plains contain vast treeless areas and 

rangelands.

The Great Plains can have hot, dry summers and cold winters, especially in 

the northern tier of states (USDA Forest Service 1989). Periodic droughts are not 

uncommon, and precipitation can be sparse. The Intermountain states also contain 

many dry areas, with extensive areas of arid desert in Arizona and New Mexico. 

Winters tend to be cold and dry, and summers warm to hot, where moisture is often 

the limiting factor for plant growth. In some areas, particularly the drier regions, 

soils (e.g., limestone soils) can have a profound effect on plant community composition (Covington et al. 1994). 

The relatively large Rocky Mountains region contains about one-third of the 

Nation’s land area and about one-fifth of the U.S. forest land, but contributes only 

5 percent of the U.S. timber harvest. Approximately three-quarters of the region’s 

forest land is publicly owned, has lower productivity on average than most other 

regions, and owner objectives often center on nontimber objectives. About half of 

the forest land in the region is classified as timberland (see “Glossary” for definitions of forest land and timberland) (Smith et al. 2001). 

Forest Cover Situation

Overall, softwood types are the dominant forest cover on timberland in the region 

(table 2). Five forest cover types totaling about 112 million acres compose about 80 

percent of the forest land in the Rocky Mountain states: pinyon-juniper, Douglasfir, fir-spruce, ponderosa pine, and lodgepole pine (fig. 26). The pinyon-juniper 

cover type is a major forest type as well as a rangeland ecosystem, occurring as a 

relatively uniform cover type, with low tree species diversity (fig. 27). This pinyonjuniper cover type occupies more than 45 million acres, generally at elevations 

(4,500 to 7,500 feet) above the desert floor and below ponderosa pine. However, 

less than one-half million acres are classified as timberland (fig. 27), because of the 

relatively low timber productivity of this cover type. The pinyon-juniper ecosystem 

is found frequently on dry plateaus and broken tablelands, such as in western Colorado, Utah, Nevada, New Mexico, and Arizona (USDA Forest Service 1989). 

Chapter 3: Rocky Mountains Region

The dominant forest 

types in the Rocky 

Mountains region 

are pinyon-juniper, 

Douglas-fir, fir-spruce, 

ponderosa pine, and 

lodgepole-pine.
40

General Technical Report PNW-GTR-613

20,969

17,910

19,338

7,524 14,277

16,895

1,060

Douglas-fir

Ponderosa pine

Fir-spruce

Lodgepole pine

Other softwoods

Hardwoods

Nonstocked

Pinyon-juniper

45,242

Figure 26—Area of forest land (thousand acres) by forest cover type in the Rocky Mountains region, 

1997 (Smith et al. 2001).

Figure 27—Pinyon-juniper covers large areas in the Rocky Mountains region.
41

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

The four forest cover types that occupy the next largest areas are Douglas-fir 

(21 million acres), spruce-fir (19 million acres), ponderosa pine (17 million acres), 

and lodgepole pine (14 million acres). These forest cover types make up the bulk 

of timberland in the region. In terms of timber production, the Douglas-fir and 

ponderosa pine types are the most important. 

Dense conifer stands are not uncommon in parts of the region, such as pure 

stands of lodgepole pine that have little, if any, understory vegetation (Hessburg 

et al. 2000). Fire-related concerns about overstocked forest stands with smalldiameter suppressed trees are not new (e.g., Cooper 1960); however, higher than 

average human population growth and associated development (Alig et al. 2004) 

within wildland-urban interfaces have increased risk from forest fires to private 

property and human life. Future impacts on conifer forest cover types are notably 

uncertain with respect to forest fire extent and policy-related interventions. 

Hardwood species have wide ranges throughout much of the Rocky Mountains 

region (fig. 28). Timberland hardwoods consist primarily of two species: quaking 

aspen (Populus tremuloides Michx.) and cottonwood (Populus spp.). At higher 

elevations, aspen is usually found as small patches or groups of patches punctuating 

the mountainsides. However, in Colorado and Utah, where two-thirds of the aspen 

is located, there are rather extensive areas. At lower elevations, the hardwoods in 

the region are typically represented by cottonwoods along streambanks and in low 

valleys and by oaks (Quercus spp.) in woodlands. 

The widespread distribution of quaking aspen forests on the region’s high 

plateaus and mountain ranges and their importance for many wildlife species make 

these forests a significant biotic community. Although aspen is considered a climax 

species on some sites, it is usually seral to conifers (fig. 29). This replacement is 

gradual and can take from 100 to 200 or more years. If an aspen stand is within 

a mixed-conifer forest, however, conifers can become established within a single 

decade. Because aspen stands are different from conifer stands, they can add to 

landscape diversity and wildlife habitat. Although aspen stems are short lived and 

snags do not stand long, the wood is soft, often decayed, and therefore useful to 

cavity-dependent species. Young sprouts are heavily browsed by elk and deer.

Aspen stands are in decline on the Colorado Plateau in parts of Arizona and 

New Mexico. The combination of modern fire suppression and a steady increase in 

elk herbivory has prevented aspen regeneration in many forests, with conifer understories now widely overtopping aspen stands. Aspen clones are able to persist in a 

suppressed state in the understories of conifers for many years, but without major 

fires, aspen stands may continue to decline.

The largest area gains 

in the Rocky Mountains 

region between 1953 

and 1997 were for 

Douglas-fir, fir-spruce, 

and the western 

hardwood forest types.
42

General Technical Report PNW-GTR-613

30

25

20

15

10

5

0

1953 1963 1977 1987 1997

Year

Timberland area (million acres)

Other softwoods

Ponderosa pine

Douglas-fir

Hardwoods

Pinyon-juniper

Figure 28—Area trends for major forest cover types on timberland in the Rocky Mountains region, 1953 to 1997 (Smith et al. 2001).

Figure 29— Without major disturbances, some aspen stands are succeeded by conifer stands in the 

Rocky Mountains region. 

Dave Powell, USDA Forest Service, www.forestryimages.org
43

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

From 1962 to 1985–87, the mixed-conifer forest type increased by 1.0 million 

acres, or 81 percent. Ponderosa pine decreased slightly in acreage, and aspen decreased by 46 percent (Johnson 1996). Many changes occur as such forests become 

denser. The character of forest fires changes. They now burn less frequently but are 

high-intensity, stand-replacing fires (Covington and Moore 1994). Forests in the 

southwest have lost much of their diversity, but they have far more trees today than 

before. 

Forest cover types with the largest area gains on the region’s timberland base 

between 1953 and 1997 were Douglas-fir, fir-spruce, and the western hardwood 

types (Smith et al. 2001). The largest area reductions were for the lodgepole, pinyonjuniper, and ponderosa-Jeffrey pine types. Overall, the biggest area change was the 

approximately 6-million-acre increase in the Douglas-fir type, with that type now 

the most common type on the region’s timberland.

Projections

Total timberland area in the Rocky Mountains region is projected to fall slightly 

from 71.0 million acres in 1997 to 70.9 million acres in 2050 (Alig et al. 2003). The 

projected decrease is largely on the NIPF ownership. Substantial areas of privately 

owned forests have been subdivided for home sites and ranchettes, particularly in 

the mountainous areas of Montana, Idaho, and Colorado. Above-average growth in 

population has contributed to more people on the region’s landscape.

Overall, the projected changes in forest cover types are relatively small compared to those for some other regions (e.g., South) (table 3, figs. 30 and 31). Softwood types are projected to remain dominant on most of the region’s timberland. 

In both the northern and southern portions of the Intermountain subregion, the 

dominant projected trend is an increase in the area of the Douglas-fir type (figs. 30 

and 31). This increase is partially offset by decreases in the areas of pine, fir, and 

spruce forest types. By subregion, the projected decreases are consistent for the 

other coniferous types, except that area of ponderosa pine is projected to increase 

in the southern subregion. 

Area of hardwoods is projected to increase in the northern portion of the 

Intermountain subregion, primarily on NIPF timberlands. In the southern portion, 

hardwood area is projected to decline. 

Projected area changes by forest cover type are in the same direction for forest 

industry and NIPF private lands, with the exception of lodgepole pine. Lodgepole 

pine is projected to decrease by more than 50 percent on NIPF timberlands and 

slightly increase on forest industry lands. 

Softwoods are projected 

to remain the dominant 

forest type in the Rocky 

Mountains region, with 

the area of Douglas-fir 

projected to increase.
44

General Technical Report PNW-GTR-613

At the time of the last RPA assessment, one issue in the Rocky Mountains 

region involved the aspen forest type and utilization trends for a forest cover type 

that is highly valued in some areas for fall foliage and other amenities. Since that 

time, oriented strand board capacity has dropped substantially; where there were 

once four operational oriented strand board plants in the U.S. West, now there are 

none (Ince 1999, 2000). At a broader level, there has been no capacity growth for 

wood pulp in the West for some time, and some mills have closed over the past 

decade or so (Ince 1999, 2000). Pulp mills in the West primarily use softwood mill 

residues, in contrast to timber harvests specifically for pulpwood (e.g., aspen) as in 

the Lake States.

Timber harvest in the Rocky Mountains represented less than 9 percent of 

the total U.S. softwood harvest in 1996, and even less of the hardwood harvests. 

The volume of total timber harvest is projected to drop slightly by 2050, mainly 

Figure 30—Projected area changes for forest cover types on forest industry timberlands in the Rocky Mountains region, 1997 to 2050. 

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

Timberland area (million acres)

Lodgepole pine

Fir-spruce

Ponderosa pine

Douglas-fir

Maple-beech

Lowland hardwood

Oak-hickory

Oak-pine

Pines

1997 2000 2010 2020 2030 2040 2050

Year
45

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 31—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Rocky Mountains region, 

1997 to 2050. 

45

40

35

30

25

20

15

10

5

0

Timberland area (million acres)

Mountain hardwoods

Lodgepole pine

Fir-spruce

Ponderosa pine

Douglas-fir

Maple-beech

Lowland hardwoods

Oak-hickory

Oak-pine

Pines

1997 2000 2010 2020 2030 2040 2050

Year

in the southern Rocky Mountains (Haynes 2003). Compared to regions such as the 

South, timber harvest over the large Rocky Mountain region is typically less frequent and does not affect forest cover on as high a percentage of forested acres. 

Decreased fire frequency owing to grazing and fire suppression triggered a 

shift to forests with very high tree densities (fig. 32), which in turn contributed to 

destructive forest fires. Options to deal with these changes include prescribed fire, 

thinning, and timber harvest to mimic natural disturbances and conditions. However, there are barriers to implementing these activities on a scale large enough 

to have a significant benefit. In the inland West, Covington et al. (1994) anticipate 

increased tree seedling establishment, intensified competition among established 

trees, further deterioration of tree vigor, and increasing tree mortality from insects, 

diseases, drought, and fire. The fire risks are related to an acceleration of historical 

changes that include increased forest fuel accumulations, lengthened fire seasons, 

and intensified burning conditions. 
46

General Technical Report PNW-GTR-613

Summary, Rocky Mountains Region

The region covers about one-third of the entire Nation and encompasses a variety 

of landforms and has diverse climatic conditions, including some large areas with 

sparse or no tree cover. Forest cover types with the largest area gains on the region’s 

timberland base between 1953 and 1997 were Douglas-fir, fir-spruce, and the western hardwood types. Largest area reductions were for the lodgepole, pinyon-juniper, 

and ponderosa-Jeffrey pine types. Overall, the biggest area change was the approximately 6-million-acre increase in the Douglas-fir type, with that type now the most 

common type on the region’s timberland. 

The Douglas-fir type also is projected to have the largest area increase in the 

future. This increase is partially offset by decreases in the areas of pine, fir, and 

spruce forest types. Hardwood area is projected to increase in the northern part of 

the region but decrease in the southern portion. 

Figure 32—Many forest stands in the Inland West have high numbers of trees per acre and are 

prone to fire risks. 
47

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Chapter 4: Pacific Coast

1

 Alaska and Hawaii are included in some tables with historical data, but were excluded from 

the modeling in the RPA timber assessment, and forest cover projections were not prepared 

for those two states. Together, the two states contain 2.6 percent of total U.S. timberland area; 

although Alaska has a relatively large forest land base, more than 90 percent of that forest land 

either has productivity too low to be classified as timberland or is reserved. 

Introduction

The Pacific Coast region has three Forest and Rangeland Renewable Resources 

Planning Act (RPA) subregions: Pacific Northwest consisting of Oregon and Washington, Pacific Southwest consisting of California and Hawaii, and Alaska1

 (fig. 1, 

table 1). Latitude and environmental conditions vary widely across the region; e.g., 

boreal conditions of Alaska versus tropical conditions of the island state of Hawaii. 

Extremes of environmental conditions owing to the latitudinal differences are 

moderated in some areas and exaggerated in others by influences of ocean currents, 

prevailing winds, and landform (USDA Forest Service 1989). However, annual 

precipitation varies across the region from 10 inches or less in the arctic zone of 

Alaska’s northern and western coastal plains to more than 150 inches in places in 

southern coastal Alaska and western Washington. 

In the maritime zone are some of the tallest trees in the world, and the most 

productive coniferous forests in the Northern Hemisphere. The redwood belt of 

California, the spruce and hemlock forests of coastal Alaska, and the portion of 

the Pacific Northwest west of the crest of the Cascade Range in Oregon and Washington (Pacific Northwest West subregion) are within the maritime zone (USDA 

Forest Service 1989).

Growing conditions for forests differ widely within the region, as forests of 

eastern Oregon, eastern Washington, and eastern California are less productive 

on average than those in the maritime zone. The better sites in the eastern parts of 

these states, however, are quite productive, yielding high-quality ponderosa pine 

(Pinus ponderosa Dougl. ex Laws.), western larch (Larix occidentalis Nutt.), true 

firs (Abies spp.), western hemlock (Tsuga heterophylla (Raf.) Sarg.) and inland 

Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) (USDA Forest 

Service 1989). 

Approximately two-thirds of the region’s forest land is publicly owned. More 

than half of the region’s forest land has a timber productivity rating below the 

threshold for timberland, much of that on public forest land in Alaska. Overall, 

public ownership accounts for 66 percent of forest land in the region, forest industry ownership for 6 percent, and nonindustrial private forest (NIPF) ownership for 

28 percent (Smith et al. 2001).

The fir-spruce cover 

type is the most 

extensive forest cover 

type in the Pacific 

Coast region.

In 1997, Douglas-fir 

was the most common 

forest type on both 

forest industry and 

NIPF timberlands in 

the Pacific Northwest 

West subregion.
48

General Technical Report PNW-GTR-613

Forest Cover Situation

Overall, softwood types are the dominant forest cover on timberland in the region 

(table 2). In terms of area, the fir-spruce cover type is the most extensive forest 

cover type in the Pacific Coast region, covering more than 50 million acres 

(fig. 33). Most of this is in Alaska and is below the productivity cutoff for timberland because of harsh climate, permafrost, shallow or poorly drained soil, or other 

environmental factors. The fir-spruce cover type in Alaska is usually associated 

with hardwoods, or follows hardwoods in ecological succession. Together, firspruce and hardwood forests cover more than 100 million acres, mostly in Alaska’s 

interior (USDA Forest Service 1989). In Oregon, Washington, and California, the 

fir-spruce cover type occupies about 10 million acres, most of which meets the 

timberland productivity standard. 

20,907

15,241

50,349

916

78,332

30,811

2,633

19,840

Douglas-fir

Ponderosa pine

Fir-spruce

Redwood

Other softwoods

Hardwoods

Nonstocked

Hemlock–Sitka spruce

Figure 33—Area of forest land (thousand acres) by forest cover type in the Pacific Coast region, 1997 

(Smith et al. 2001).

The most important forest type, in terms of timber production, in the region is 

Douglas-fir. This cover type occupied more than 20 million acres in 1997 (Smith 

et al. 2001). The best sites are capable of yielding more than 200 cubic feet per acre 

per year of wood, and more than one-half of the cover type’s area can yield more 

than 120 cubic feet (fig. 34). 
49

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 34—Douglas-fir is an important commercial timber 

species in the Pacific Coast region, which contains some of 

the most productive forests in the world. 

The Douglas-fir forest 

type is managed under a 

broad range of management 

regimes, from custodial 

management to plantings 

with genetically improved 

stock, precommercial 

thinning, and fertilization 

resulting in substantial differences in growth by treatment (Haynes 2003). The 

dominance of the Douglasfir forest type and species 

in the region is a result of 

the species’ high growth 

capacity, its adaptability 

to high-intensity management (e.g., its ability to 

reforest clearcuts), and the 

high economic value of its 

wood. There are a number 

of factors influencing the composition of Douglas-fir stands, if not the total area in 

this forest type. For example, the increased diversity of seedlings being planted and 

changes in management intensities (such as rotation lengths and vegetation control) 

are influencing the composition and structure of trees within this forest type.

In 1997, Douglas-fir was the most common forest type on both forest industry 

and NIPF private timberlands in western Oregon and western Washington (Pacific 

Northwest West subregion). Douglas-fir accounted for 55 percent of the private 

timberland, whereas hemlock-spruce occupied 14 percent, red alder occupied 13 

percent, other hardwood occupied 10 percent, and other softwood occupied 5 percent of the private timberland. The majority of Douglas-fir, 73 percent, and hemlock-spruce, 83 percent, were on forest industry lands, and the other forest types 

were more evenly distributed between the private owner groups. 

The Douglas-fir cover type is a collection of many different plant communities. 

The dominant species within the Douglas-fir cover type were generally the same 

between ownerships, but the relative importance of the species differed. Douglasfir (Pseudotsuga menziesii (Mirb.) Franco) was the dominant species, occupying 75 

percent of the timber volume of forest industry and 74 percent of the timber volume 

The largest changes in 

forest type areas in the 

Pacific Northwest West 

between 1977 and 1997 

were the loss of red 

alder and the gain of 

Douglas-fir.

Softwood types are 

projected to remain the 

dominant forest cover 

type in the Pacific 

Coast region, as more 

area is planted to 

Douglas-fir.
50

General Technical Report PNW-GTR-613

of NIPF stands. Western hemlock and red alder (Alnus rubra Bong.) were the next 

most abundant species in the Douglas-fir forest type. 

The forests of the Pacific Northwest West subregion are continually changing in 

response to harvesting patterns and natural succession (fig. 35) (Alig et al. 2000c). 

The forest dynamics of the region are in a transitional stage, with some historical 

patterns being altered by current economic and social factors, such as ownership 

patterns, timber markets, management regulations, and changing management 

objectives. Before the 1990s, a large proportion of the timber harvested in the 

region came from national forests, but federal regulations have greatly reduced 

the allowable cut on federal lands to allow for protection of the northern spotted 

owl (Strix occidentals caurina) and other species deemed dependent upon latesuccessional habitat for parts of their life cycles. As the level of federal timber 

harvests decreased, the importance of timber harvested from private lands increased. Timber harvests on federal lands have dropped sharply since the early 

1990s (figs. 36 through 38), and some demands have shifted to private timberlands, leading to shorter timber rotations and more opportunities for cover type 

change at time of regeneration (Haynes 2003). 

25

20

15

10

5

0

1953 1963 1977 1987 1997

Year

Timberland area (million acres)

Douglas-fir

Other softwoods

Ponderosa pine

Hardwoods

Pinyon-juniper

Figure 35—Area trends for major forest cover types on timberland in the Pacific Coast Northwest (Oregon and Washington), 1953 to 

1997 (Smith et al. 2001).
51

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Timber harvest (million cubic feet)

Historical Projected

Softwood

Hardwood

2,500

2,000

1,500

1,000

500

0

1940 1960 1980 2020 2040 2060

Year

2000

Figure 36—Trends in timber harvest volumes from public and private timberlands in the Pacific Northwest (Oregon and 

Washington), 1953 to 1997, with projections to 2050.

Forest cover types with the largest area gains on the region’s timberland base 

between 1953 and 1997 were two with relatively small areas: fir-spruce and the 

western hardwood types (Smith et al. 2001). The region had a net loss of 3.3 million 

acres of timberland, with the largest area reductions for the ponderosa-Jeffrey pine 

and western white pine types. Reclassification of timberland to another forest-land 

class (e.g., reserved forest land) has affected area changes for forest types on timberland. The Douglas-fir type has been affected by such changes, but in 1997 was 

still the most common type on the region’s timberland, covering 26 percent.

The largest changes in forest type areas on private timberlands in the Pacific 

Northwest West subregion between 1977 and 1997 were the loss of red alder and 

the gain of Douglas-fir (Smith et al. 2001). The trends and magnitudes of historical 

changes varied by ownership. Other hardwood area increased on forest industry 

timberlands and decreased on NIPF timberlands. The forest industry lost significantly more western hemlock-Sitka spruce and gained significantly more Douglasfir than the NIPF owners.

Timber demand, competing land uses, technology, and public policies also 

have influenced the forest type dynamics of the region. The increasing demand for 

timber on regional and global markets has placed high values on many of the forest 

products and provides incentives for forest management that produces trees with 

The dominance of 

Douglas-fir on private 

lands in the Pacific 

Northwest West is 

projected to continue 

for at least the next 

50 years.
52

General Technical Report PNW-GTR-613

Figure 38—U.S. timber harvest by major forest ownership and species group (1997).

Softwoods Hardwoods

Species group

Timber harvest (million cubic feet)

6,000

5,000

4,000

3,000

2,000

1,000

0

National forest

Other public

Forest industry

Nonindustrial private forest

Figure 37—Trends in timber harvest by selected U.S. regions, 1953 to 1997, with projections to 2050.

Historical Projected

Softwood—U.S.

Hardwood—U.S.

Softwood—South

Hardwood—South

Softwood—Pacific Northwest West

Timber harvest (million cubic feet)

16,000

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

1940 1960 1980 2020 2040 2060

Year

2000
53

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

specific quality and size attributes. Residential and commercial land uses are the 

greatest sinks of timberland, and these pressures will be increasing as the population of the region increases. Technologies, such as genetically improved seedlings, 

are helping forest landowners meet their objectives. Public policies have provided 

incentives and disincentives for specific forest management practices. For example, 

there are laws in Oregon and Washington that limit clearcut sizes and require specific levels of regeneration following harvest activities.

Projections

Total timberland area in the Pacific Coast region is projected to fall from 72.2 million acres in 1997 to 69.3 million acres by 2050. As in the Rocky Mountains, most 

of the projected reduction is for the NIPF ownership (Kline and Alig 2001). Much 

current timberland in the Pacific Coast region is located on lands where forestry has 

a competitive advantage or is a residual land use owing to physiography. Projected 

changes are smaller than historical ones. The projected net area changes reflect 

direct conversion of timberland to urban and developed uses and other acres converted to replace cropland lost to urban and developed uses. 

Overall, softwood types are projected to remain the dominant forest cover types 

on timberland in the region (table 3). The most substantial cover type changes in the 

Pacific Coast region are projected to occur on forest industry lands, as more area is 

planted to Douglas-fir, especially in the Pacific Northwest West subregion (figs. 39 

through 44). These changes are stimulated by the increased value of Douglas-fir. 

Douglas-fir is the most common forest type for stands to transition to regardless 

of harvest type. These transition rates were generally higher for the forest industry 

than for NIPF owners. Douglas-fir also had the highest probability of remaining in 

the same forest type following a given disturbance, except for partial harvests on 

forest industry timberlands. 

Douglas-Fir in the Pacific Northwest West Subregion

Douglas-fir is the most common forest type in the Pacific Northwest West subregion, and this dominance on private lands is projected to continue for at least the 

next 50 years (figs. 41 and 42). The forest industry is the principal owner of this 

forest type, and the area of Douglas-fir on their timberlands is projected to increase. 

Much of the increase in the area of Douglas-fir on the forest industry timberlands 

is transitioning from western hemlock-Sitka spruce and red alder and other hardwoods following final harvests. 

Although the area of Douglas-fir is projected to have a net increase on private 

timberlands, the net area change of the Douglas-fir cover type on NIPF timberlands 
54

General Technical Report PNW-GTR-613

Figure 39—Projected area changes for forest cover types on forest industry timberlands in the Pacific Northwest East subregion, 

1997 to 2050. 

Figure 40—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Pacific Northwest East 

subregion, 1997 to 2050. Timberland area (million acres)

6

5

4

3

2

1

0

1997 2000 2010 2020 2030 2040 2050

Year

Lodgepole pine

True fir

Douglas-fir and larch

Ponderosa pine 

Timberland area (million acres)

6

5

4

3

2

1

0

1997 2000 2010 2020 2030 2040 2050

Year

Hardwood

Lodgepole pine

True fir

Douglas-fir and larch

Ponderosa pine 
55

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 41—Projected area changes for forest cover types on forest industry timberlands in the Pacific Northwest West subregion, 1997 

to 2050. 

Figure 42—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Pacific Northwest West 

subregion, 1997 to 2050. Timberland area (million acres)

8

7

6

5

4

3

2

1

0

1997 2000 2010 2020 2030 2040 2050

Year

Other hardwood

Red alder

Other softwood

Western hemlock–

 Sitka spruce

Douglas-fir

Timberland area (million acres)

1997 2000 2010 2020 2030 2040 2050

Year

Other hardwood

Red alder

Other softwood

Western hemlock–

 Sitka spruce

Douglas-fir

6

5

4

3

2

1

0
56

General Technical Report PNW-GTR-613

Figure 43—Projected area changes for forest cover types on forest industry timberlands in the Pacific Southwest subregion, 

1997 to 2050. 

Figure 44—Projected area changes for forest cover types on nonindustrial private forest timberlands in the Pacific Southwest subregion, 

1997 to 2050. Timberland area (million acres)

1997 2000 2010 2020 2030 2040 2050

Year

Hardwood

Mixed conifer

Redwood

Fir-spruce

Ponderosa pine

Douglas-fir 

6

5

4

3

2

1

0

Timberland area (million acres)

1997 2000 2010 2020 2030 2040 2050

Year

Hardwood

Mixed conifer

Redwood

Fir-spruce

Ponderosa pine

Douglas-fir 

6

5

4

3

2

1

0
57

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

between 1997 and 2050 is a small decrease. Some of the NIPF Douglas-fir is being 

lost to nontimberland land uses, such as residential areas (Alig et al. 2000c, Kline 

and Alig 2001, Zheng and Alig 1999), but most of the losses result from transitions to the hardwood forest types following final and partial harvests. This may 

result from insufficient regeneration efforts following harvests or from changing 

landowner objectives. Insufficient regeneration is probably only a partial answer 

because of the regeneration regulations in Oregon and Washington that require, 

to varying degrees, the establishment of a number of free-to-grow trees within a 

specified period following final harvests. The high numbers of Douglas-fir in the 

other hardwood forest type may be an indicator that regeneration is not the issue, 

but a lack of control of competing vegetation may be more relevant. 

The forest type transition probabilities used in the projections differed by harvest type, but the patterns were similar between the two private owner groups (figs. 

41 and 42). Although the general trend of relatively high probabilities of retention 

in and transition to Douglas-fir was common to both ownerships, the magnitudes 

of these changes did differ. For example, 78 percent of the forest industry Douglasfir stands that were final harvested remained Douglas-fir, whereas 58 percent of the 

harvested Douglas-fir stands on NIPF timberlands remained as Douglas-fir. 

The type transition matrices for final harvests used in the projections were 

calculated from USDA Forest Service Forest Inventory and Analysis (FIA) and 

American Forest and Paper Association (AF&PA 1999) data were similar in trends 

but differed in magnitudes (see app. 1). The major difference was that the AF&PA 

matrix showed higher levels of Douglas-fir retention, higher probabilities of stands 

transitioning to Douglas-fir after final harvests of other softwood or other hardwood 

stands, and lower transition rates to Douglas-fir following western hemlock–Sitka 

spruce or red alder final harvests. 

Other Forest Cover Types in the Pacific Northwest 

West Subregion

Besides Douglas-fir, red alder was the most common (11 percent) forest type that 

Douglas-fir transitioned to in projections for forest industry timberlands, and other 

hardwood was the most common (21 percent) forest type that Douglas-fir transitioned to on NIPF timberlands. 

Another example of ownership differences is that 5 percent of the red alder 

stands that were projected for final harvest remained as red alder, and 86 percent 

became Douglas-fir on forest industry timberlands. On NIPF timberlands, 39 percent of the red alder stands that were final harvested remained red alder, and 

40 percent became Douglas-fir. This contributes to the projection of a reduction 

Relatively high 

probabilities of 

retention in and 

transition to 

Douglas-fir are 

common to both 

ownerships.
58

General Technical Report PNW-GTR-613

in hardwood area, especially on forest industry lands. Hardwood area on NIPF 

lands is also projected to decline, but the net loss masks some gains from other 

types (fig. 42). On NIPF timberlands, the other hardwood type area is projected 

to increase.

The projected decreases in the area of red alder on forest industry and NIPF 

lands are continuations of historical trends that have been influenced by relatively 

low market values for hardwood species such as red alder. Although the most current data do not reflect it, this trend may be changing because the market value of 

red alder is increasing. Although economic incentives for growing red alder are 

increasing, forest practice regulations encourage removal of some red alder (and 

other hardwoods) from riparian management areas and conversion of these riparian 

forests to conifer-dominated forest types to enhance aquatic habitats. Other projections largely follow historical trends, although the projected trends of the other 

hardwood forest type do depart from the historical trends. 

Forest Cover Projections for Other Subregions

For the Pacific Northwest East subregion, areas of most forest cover types on private timberlands are projected to decrease (figs. 39 and 40). Areas of the ponderosa 

pine and Douglas-fir/larch cover types, which cover about three-quarters of private 

timberlands, are projected to slowly decrease. Trends are consistent across both 

private ownership classes. 

For the Pacific Southwest subregion, areas of most forest cover types on private 

timberlands are also projected to decrease (figs. 43 and 44). Exceptions are slight 

increases for the Douglas-fir and fir-spruce cover types. The trends are consistent 

across both private ownership classes, with one exception being the small increase 

in ponderosa pine area for forest industry. 

Summary, Pacific Coast Region

In 1997, the most extensive forest covers on private land were Douglas-fir in the 

Pacific Northwest West subregion, Douglas-fir and ponderosa pine in the Pacific 

Northwest East subregion, and mixed conifers and hardwoods in the Pacific Southwest subregion. Douglas-fir is the major type in western Oregon and Washington, 

where it occupies about 60 percent of the forest area. Examples of other forest types 

that cover more than 10 million acres in a subregion are fir-spruce in Alaska and 

western hardwoods in the Pacific Southwest.

For the Pacific Coast region, the largest projected changes in the areas of 

forest types on private timberland are in the Pacific Northwest West subregion. 

This area experienced a large reduction in federal timber harvest in the 1990s 

Areas of most forest 

cover types in the 

Pacific Northwest 

East and Pacific 

Southwest are 

projected to decrease 

on private timberlands.
59

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

because of increased protection for threatened and endangered wildlife species. 

This has shifted timber demand more to private timberland and other regions. Projected changes in forest cover areas include a decrease in the area of red alder and 

an increase in the area of Douglas-fir. The regional trends are dominated by the forest type dynamics of the forest industry because of their larger area of timberland. 

The changes are being spurred by the increased value of Douglas-fir. Conversely, 

hardwood area on this ownership is projected to decline. On NIPF timberlands, 

the largest projected changes are an increase in the area of other hardwood and 

decreases in the areas of Douglas-fir and red alder. Projected timberland losses on 

NIPF lands are distributed across all forest types. Projections include increases in 

other hardwood and other softwood types and decreases in the areas of red alder 

and western hemlock–Sitka spruce types. 

For the Pacific Northwest East subregion, areas of most forest cover types on 

private timberlands are projected to decrease. Areas of the ponderosa pine and 

Douglas-fir–larch cover types, which cover about three-quarters of private timberlands, are projected to slowly decrease. The trends are consistent across both 

private ownership classes. 

For the Pacific Southwest subregion, areas of most forest cover types on 

private timberlands are projected to decrease. Exceptions are slight increases 

for the Douglas-fir cover type and fir-spruce cover type. 
60

General Technical Report PNW-GTR-613
61

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Introduction

This chapter provides a national overview of the area projections for forest cover 

types. The endowment of 2.263 billion acres of land in the United States includes 

33 percent (747 million acres) that is forest land. Forests are found in significant 

amounts in every region of the Nation. They range from sparse scrub forests of 

the arid, interior West to the highly productive forests of the Pacific Coast and the 

South, and from pure hardwood forests to multispecies mixtures and coniferous 

forests. About two-thirds (504 million acres) of the Nation’s forests are classed as 

timberland, productive forests capable of producing 20 cubic feet per acre of industrial wood annually and not legally reserved from timber harvest (figs. 2 and 45). 

An additional 52 million acres of forest, reserved for nontimber uses, are managed 

by public agencies as parks or wilderness areas. Other forest lands on the remaining 

Chapter 5: National Overview

Timberland Reserved 

forest land

Other forest land

Forest land area (million acres)

600

500

400

300

200

100

0

1987

1997

Figure 45—Composition of U.S. forest land by timberland, reserved for nontimber uses, 

and other forest land that has lower timber productivity (Smith et al. 2001).
62

General Technical Report PNW-GTR-613

191 million acres are not capable of producing 20 cubic feet per acre of industrial 

wood annually but are of major importance for watershed protection, wildlife habitat, domestic livestock grazing, and other uses and services. More than 90 percent 

of the “other” forests (see “Glossary” for definitions) are in the West, with more 

than half in Alaska. 

Macro View of Forest Cover Projections 

Projections of softwood and hardwood areas for the United States are shown in 

figure 46. Softwood area is projected to increase by 11 percent by 2050. Hardwood 

area drops by 8 percent, but in the East still dominates in both the North and South 

regions (fig. 47).

Table 4 lists the 12 largest amounts of projected regional area change for forest 

cover types. The largest projected changes in timberland area are for the South 

and North, the regions with the most existing timberland. The North is projected 

to have relatively small percentage changes in extensive types such as the maplebeech-birch type (less than 5 percent), whereas the South has larger percentage 

changes. This follows recent historical trends, as one of the largest changes in U.S. 

forest cover area over the last half century has involved pine cover types in the 

South. The South has the largest amount of relatively high productivity forest land 

in the United States (fig. 4), with many areas suitable for pine plantations. Area of 

planted pine in the South has increased more than tenfold since 1950, mostly on 

private lands (USDA Forest Service 1982, 1988, 2001). With respect to projections, 

Table 4—The 12 largest projected changes in forest cover areas in the United 

States between 1997 and 2050 by subregion, private ownership group, and forest 

cover type

Change

Subregion Ownership group Forest type Area Percentage

Million acres

South Central Nonindustrial private Upland hardwood -7.6 -19

South Central Forest industry Planted pine 5.7 81

South Central Nonindustrial private Planted pine 4.4 88

Southeast Nonindustrial private Natural pine -3.4 -28

South Central Forest industry Upland hardwood -2.5 -58

Northeast Nonindustrial private Elm-ash-red maple 2.4 101

Southeast Nonindustrial private Planted pine 2.3 29

Northeast Nonindustrial private Fir-spruce -2.0 -49

Southeast Forest industry Planted pine 1.9 26 

Great Plains Nonindustrial private Maple and beech 1.6 21

South Central Nonindustrial private Oak-pine 1.5 12

Lake States Nonindustrial private Aspen-birch -1.5 -23

U.S. softwood area on 

private timberland is 

projected to increase 

by 11 percent by 2050.

U.S. hardwood area on 

private timberland is 

projected to decrease 

by 8 percent by 2050.
63

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Percentage of private timberland

80

70

60

50

40

30

20

10

0

1997 2010 2020 2030 2040 2050

Year

Hardwood

Softwood

Figure 46—Projected percentages of softwood and hardwood type groupings on private timberlands 

in the United States.

Figure 47—Projected percentage of private timberland in softwood forest type groupings by region, 

1997 to 2050. Percentage of private timberland

80

70

60

50

40

30

20

10

0

1997 2010 2020 2030 2040 2050

Year

Pacific Coast

South

North and Rocky Mountains
64

General Technical Report PNW-GTR-613

the South also has relatively large changes: reductions of 19 percent for upland 

hardwood on nonindustrial private forest (NIPF) timberlands and 58 percent on 

forest industry timberlands in the South Central region; and increases in excess of 

25 percent for planted pine on both private ownerships in the South. The increase in 

planted pine is the result of the assumed intensification of forestry practices in the 

South, a continuation of a current trend. 

Although the area of softwoods is projected to increase across many regions 

of the country, especially on forest industry lands, hardwoods will remain the 

dominant forest type on private lands. One of the areas of largest change will be 

in the Southern United States. In particular, the relative areas of hardwoods and 

softwoods on forest industry lands are projected to increase from a nearly 1:1 ratio 

of softwoods to hardwoods in 1997 to a 3:1 ratio in 2050. On NIPF timberlands, the 

area of hardwoods is projected to remain dominant, but the 3:1 ratio of hardwoods 

to softwoods is projected to decrease to about a 2.5:1 ratio by 2050.

However, these net changes only tell part of the story. An examination of the 

gross changes shows a much more dynamic system. For example, the projected net 

increase of 14 million acres of planted pine in the South is the result of a gain of 

nearly 53 million acres of planted pine and a loss or reversion to other types of 

approximately 39 million acres out of planted pine. 

Other major projected changes are an increase in the area of elm-ash-red maple 

forests in the Northeast and decreases in the areas of spruce-fir in the Northeast 

and aspen-birch in the Lake States. The increase in elm-ash-red maple is primarily 

due to the large influx of red maple in the region. The projected decrease in firspruce is related to the large areas infected by insect pests (e.g., spruce budworm) 

(Choristoneura spp.). The loss of aspen-birch has largely been the result of insufficient regeneration opportunities for this early successional forest type.

The largest impact on forest cover dynamics in the United States in the recent 

past has been human influences, especially changes in land management objectives. In the last half of the 20th century, application of intensive forestry has in 

some cases influenced the composition, structure, and ecological processes of 

forests. For example, plantations and clearcutting have replaced natural regeneration and selective harvesting on some sites in the United States. Intensive forestry 

on private timberland has generally reduced rotation lengths, which leads to more 

frequent regeneration opportunities and increases the probabilities of more forest 

cover changes. At the same time, a countervailing trend is seen in expansion of the 

number of forested acres acquired by private owners for purposes other than timber 

production. This growth in nontimber objectives and the incorporation of forest 

The largest impact on 

forest cover dynamics 

in the United States 

has been from human 

influences, such as 

timber harvests.

Although the U.S. 

area of softwoods is 

projected to increase 

across many regions, 

hardwoods will remain 

the dominant forest 

type on private lands.
65

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 48—Human-caused influences, including tree planting, timber harvests, and conversion of 

forests to developed uses, are a major factor in forest cover type changes in the United States, 

lands into residential ownerships has reduced the likelihood of some acres being 

intensively managed.

Another notable human-caused influence on forest cover area was government 

subsidized afforestation, principally, planted pine in the South (fig. 48). Cost-sharing for establishment has been important for NIPF owners (Alig et al. 1990b). 

Retention of subsidized plantations also has been relatively high (Alig et al. 1980, 

Kurtz et al. 1996). 

Timber harvest is an important human-caused disturbance that has significant 

influences on forest composition and structure. Human disturbances result when 

people consciously or unconsciously alter the composition or structure of a forest. 

Timber management and land conversion are the most prevalent human disturbances in the forests of the United States. Natural disturbances include blowdowns 

from windstorms and hurricanes, lightning-induced fires, insect and disease outbreaks, and flooding. Many human disturbance events have large cumulative effects 

even if the individual disturbance events are localized. Some significant cumulative effects include the one-third reduction in U.S. forest cover since settlement by 

European Americans and fire suppression that has changed the dynamics of many 

ecosystems. Not all human-induced disturbances are localized; a notable exception 

is the chestnut blight that has eradicated chestnut trees (Castanea dentata Marsh. 

Borkh.) from eastern deciduous forests. The effects of natural disturbances span 

a broad range of spatial scales and generally are more episodic than human dis-
66

General Technical Report PNW-GTR-613

turbance. The relative importance of disturbances differs by region. Human-caused 

disturbances are a function of ownership objectives and land rent, the latter being 

influenced by stumpage value, extraction costs, and distance to markets (Alig et al. 

2003, Adams and Haynes 1996). Natural disturbances are a function of stand composition, stand structure, and distance to disturbance vectors. 

Data from periodic forest surveys by the USDA Forest Service Forest Inventory and Analysis (FIA) units indicate a notable historical reduction in the area of 

nonstocked timberland from 1953 to 1997 (table 2, Smith et al. 2001). In general, 

nonstocked area was reduced in all regions between 1953 and 1997, with an overall 

national reduction of 85 percent. Some nonstocked areas are scheduled for reforestation, but at the time of the survey were not forested. Nonstocked area is about 

1 percent of total national timberland area. The projections similarly show the 

nonstocked percentage to remain below historical levels. 

Relationships Between Land Use and Land Cover Changes

From a national viewpoint, consideration of macrodemographic and socioeconomic forces helps one understand how areas in forest cover types are affected by 

exogenous factors such as population growth. Population growth is expected to 

continue and will lead to further deforestation. Deforestation is a part of forest type 

dynamics, which can be separated into forest-land gain (afforestation), forest-land 

loss (deforestation), disturbance, and succession processes. Gains of forest land occur 

when an area that was previously nonforested becomes forested, such as afforestation 

resulting in the conversion of an agricultural field to a conifer plantation. Given the 

possibility of two-way flows of land into and out of forestry, the specific pathways by 

which forest land is gained or lost in a locality will influence the characteristics of 

the residual forests. Losses of forest land occur when an area of land is converted 

from forest land to a nonforest-land use, such as a residential development. 

The United States population is projected to increase by more than 120 million 

people over the next 50 years, and projections of population and general economic 

activity are the foundations for long-term analysis of the land use change and forest 

type changes (Alig et al. 2003, 2004). Within the macroeconomic outlook, the larger 

population will have larger incomes on average. Above-average population growth 

is projected for the South and West. In the South, projected conversion of forest land 

to developed uses involves millions of acres (Alig et al. 2003, Wear and Greis 2002), 

leading some to term it a major threat to forest sustainability. Per capita forest area 

in the United States is projected to decline from approximately 4.8 acres in 1997 to 

1.8 acres in 2050. The corresponding decline for per capita timberland is from 1.8 

to 1.2 acres. 

Continued increases in 

urban and developed 

areas are projected at 

almost all state levels, 

mostly leading to 

reduced forest cover 

area.
67

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Continued increases in urban and developed areas are projected for most 

states, mostly leading to reduced forest area. Table 5a shows examples from the 

Southern United States of exit transition probabilities of forest land by forest cover 

type for deforestation cases, and table 5b shows entry transition probabilities for 

afforestation cases. Transition probabilities by region were used as part of the 

national 2000 Forest and Rangeland Renewable Resources Planning Act (RPA) 

assessment. Projections to reflect forest type dynamics is the second of two phases 

Table 5a—Proportions of timberland gains by forest type and ownership based 

on forest survey data for private timberlands in the Southern United States

Region and forest type Forest industry Miscellaneous corporate Other private

Southeast:

 Planted pine 0.568 0.374 0.439 

 Natural pine .229 .258 .230 

 Oak-pine .012 .153 .096 

 Upland hardwood .046 .134 .146

 Lowland hardwood .114 .069 .066

 Nonstocked .031 .012 .023 

South Central:

 Planted pine .243 .076 .092 

 Natural pine .098 .065 .076 

 Oak-pine .079 .077 .091 

 Upland hardwood .355 .647 .656

 Lowland hardwood .210 .128 .080

 Nonstocked .015 .007 .005

Table 5b—Proportions of timberland losses by forest type and ownership based 

on forest survey data for private timberlands in the Southern United States

Region and forest type Forest industry Miscellaneous corporate Other private

Southeast:

 Planted pine 0.255 0.172 .055 

 Natural pine .157 .186 .177 

 Oak-pine .149 .087 .142 

 Upland hardwood .335 .501 .560 

 Lowland hardwood .050 .021 .030 

 Nonstocked .054 .034 .036 

South Central:

 Planted pine .185 .075 .044 

 Natural pine .308 .204 .181 

 Oak-pine .120 .107 .131

 Upland hardwood .260 .383 .503

 Lowland hardwood .127 .231 .138

 Nonstocked 0 0 .003

Note: Within an ownership and forest type combination, the proportions should sum to one (within 

rounding error) down a column.
68

General Technical Report PNW-GTR-613

in a protocol to assess land use and land cover dynamics in the 10 regions and 

subregions recognized in the RPA assessment. The first phase of this makes area 

projections of forest and other land uses (Alig et al. 2003, 2004). 

Links to Other Resource Planning Act Assessment Models 

The methods used to project timber supplies in the RPA timber assessment (fig. 49) 

require assumptions relating to timberland area change, trends in future management investment, the efficiency of harvest utilization, and harvest flows from public 

timberlands. The 2000 RPA assessment assumes a continuation of recent government policies such as those related to forest resources, paper recycling, tree planting assistance, trade, or environmental protection. For example, we assume that no 

major tree planting programs will be funded over the projection period. 

Harvests are a major factor in forest type transitions, and timber harvests from 

timberland within the national forests have decreased dramatically in the 1990s 

as the result of changes in the goals for federal land management. National forest 

timber harvests currently represent less than 10 percent of the U.S. timber supply (Smith et al. 2001). Under the base case assumption of continuation of current 

policies, national forest harvest is projected to continue at these lower levels for the 

next five decades (Mills and Zhou 2003), representing expectations based on current USDA Forest Service policy guidelines. Timber harvests are projected to rise 

slightly in some regions, reflecting actions to maintain forest health consistent with 

current regulations. 

Given the assumption about federal timber harvests, private timber harvest is 

projected to supply about 90 percent of the Nation’s timber harvest. This includes 

some lowered timber harvest ages (Haynes 2003). In the 2000 RPA timber assessment, the supply of timber at any point in time is based on the contributions of 

four broad groups of timberland owners: national forest, other public, forest industry, and nonindustrial private. Timber available in any period from the public 

landowners is assumed to be set by agency direction. The two private ownerships—

forest industry and nonindustrial private—are modeled as a function of the private 

timber inventory levels and stumpage prices (Adams and Haynes 1996). Private 

inventory levels and stumpage prices are both affected by the areas in different 

forest cover types. 

In the past, technological changes have substantially influenced the yields for 

certain crops, including timber production, and also have affected the demand for 

certain products. Use of historical data reflects some trends in technological changes, whereas some technological changes cannot be foreseen. Changes in technology 

have been affecting the mix of softwood and hardwood fiber used by the pulp and 
69

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 49—Bioeconomic system of models used in the 2001 RPA timber assessment (Haynes 2003).

TAMM ATLAS

Macroeconomic

data

Forest

resource

data

NAPAP

Fuelwood

 assumption

Compute inventory and 

growth parameters

Prices and

 quantities

Inventory

Growth

Removals

Fuelwood

 demand

AREACHANGE

Stumpage

 prices

Timberland

 area

Contemporaneous

feedback or interaction

Exogenous, one-time input

Timber

 harvest

 area
70

General Technical Report PNW-GTR-613

paper industry (e.g., Ince 2000). One finding from the 2000 RPA timber assessment 

that represents a departure from the past is the increasing scarcity of hardwood 

timber supplies. To augment hardwood production from traditional timberlands, 

hardwood agrifiber supply—growing hardwoods such as hybrid poplars (Populus

spp.) or cottonwoods (Populus spp.) on agricultural lands for fiber products—has 

been developed commercially on a limited scale in the United States. 

About 0.1 to 0.2 million acres of agricultural land were planted in short-rotation woody crops in the 1990s (less than 0.1 percent of current U.S. cropland area). 

Hardwood agrifiber plantations on agricultural land have much higher potential 

productivity than natural hardwoods in forest stands, typically up to five or six 

times higher, but higher productivity comes at the expense of higher costs. The 

RPA base case analysis assumes that hardwood agrifiber supply has a potential to 

expand in the future if projected equilibrium prices for hardwood pulpwood are 

sustained at levels that are high enough to justify the higher costs of agrifiber supply (e.g., Alig et al. 2000a). Benefits from alternative use of the land in agriculture 

represent opportunity costs, but real prices for agricultural products are not projected to rise over the projection period (USDA Forest Service 2001). Another key 

assumption about short-rotation woody crops in the base case outlook is that there 

are no productivity or cost-saving improvements over the projection period.

Investigations of the possible influence of global climate change on forest cover 

areas are relatively recent. Our RPA projections embody whatever related influences are embedded in the historical time series of FIA data pertaining to forest 

cover types. Recent climatic changes have enhanced plant growth in northern mid 

and high latitudes (Irland et al. 2001). In large-scale simulations for a national climate change assessment, Alig et al. (2002a) projected an increase in net economic 

welfare, based partially on expanded forest area in the northern latitudes owing 

to global climate change as predicted by ecological models. To date, most earlier 

projections of climate change on forest cover area changes are relatively small 

compared to nearer term impacts from timber harvest, land use changes, and other 

human-caused factors. Changes in forest cover are also considered as policy options 

regarding mitigation activities (e.g., Alig and Butler, in press; Birdsey et al. 2001; 

Sohngen and Alig 2000). In particular, increases in planted pine are a focus of some 

policy deliberations. 

More broadly, land use and land cover changes are part of global change, with 

feedbacks among land use, land cover, climate, and other parts of the biosphere 

(Alig 2003). As new findings accumulate, these can be used in scenario analyses 

to help place in perspective different sources of uncertainty and how they affect 

projected outcomes regarding future areas for forest cover types. 
71

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Sustainability Issues and Land-Based Policies

There is increasing interest in large-scale forest sustainability analyses and related 

aspects including changes in forest cover types. The 2000 RPA assessment is the 

first national-scale assessment in the United States to be organized around criteria 

for sustainable forest and rangeland management. These criteria include biological 

diversity; productive capacity of forest and rangeland ecosystems; forest and rangeland ecosystem health and vitality; forest contributions to global carbon cycles; 

socioeconomic benefits to meet the needs of societies; and the legal, institutional, 

and economic framework for forest and rangeland conservation and sustainable 

management. Forests are a critical natural resource of the United States, and the 

distribution of forest cover types is an indicator of the sustainability of the Nation’s 

forests (Alig and Haynes 2002, United Nations Conference on Environment and 

Development 1993). Forests provide numerous amenities that foster the well-being 

of the Nation including raw materials for the paper and lumber industries, myriad 

habitats for a multiplicity of species, filtration systems to purify air and water, and 

recreational opportunities for countless individuals. 

With the context of the latest RPA assessment broadening over earlier ones, 

this reflects increased interest in sustainable management of the world’s forest 

resources, owing in part to the United Nations Conference on Environment and 

Development in 1992 (USDA Forest Service 2001). Since that time, various countries have joined together to discuss and attempt to reach consensus on ways to 

evaluate progress toward the management of their forest resources. The United 

States participates in the Montreal Process, designed to use a set of criteria and indicators for the conservation and sustainable management of temperate and boreal 

forests. The criteria provide a common framework for describing, assessing, and 

evaluating a country’s progress toward sustainability at the national level. 

Information from periodic RPA assessments can help shape perceptions about 

whether we can sustain both increasing consumption of forest products and forest 

resource conditions (Alig and Haynes 2002). Related data illustrate the dynamics of 

our Nation’s land base and how adjustments are likely to continue in the future. The 

projections of land use and forest cover changes also provide inputs into a larger 

system of models that project timber resource conditions and harvests, wildlife 

habitat, and other natural resource conditions (USDA Forest Service 2001). Current 

debates about sustainability involve both physical notions of sustainability and competing socioeconomic goals for public and private land management. The land-base 

changes also indicate the importance of viewing “sustainability” across the entire 

land base and across sectors, in contrast to the current typical sector approach as in 

examining “sustainable forest management” (Alig and Haynes 2002). We do offer 

Information from 

periodic RPA 

assessments, such 

as concerning forest 

cover trends, can 

help shape perceptions 

about whether we can 

sustain both increasing 

consumption of 

forest products and 

certain forest resource 

conditions. 
72

General Technical Report PNW-GTR-613

the periodic RPA assessments as a unique process that has monitored the forest 

resource situation and provided comprehensive analyses. Reassessments over time 

are necessary because of the dynamics on the land base, as well as changing social 

values. This is in contrast to “sustainability analyses” that propose to place the discussion of sustainability into a two-dimensional framework where the focus is on 

the status at a point in time as well as how indicators change over time. 

The RPA forest cover projections were one input into an analysis by Haynes 

et al. (2001) that drew upon RPA timber assessment projections to provide broadscale composite measures to look at tradeoffs, compatible production, and the 

integrative nature of forest ecosystems. They used total timberland area as one of 

the six indicators of a biophysical index, termed timberland integrity. Haynes et al. 

(2001) also used softwood percentage as another indicator, drawing upon forest 

cover projections. They proposed a timberland wealth measure in line with socioeconomic indicators, as a relatively parsimonious measure of the various economic 

and social criteria, i.e., a broad proxy for ecosystem wealth. Haynes et al. (2001) 

used total timber inventory in this measure, which is based in part on timberland 

area projections. Their results show that there has been a general decline in timberland integrity since 1952 but that the decline has slowed in the 1990s and is 

expected to stabilize in the future. In contrast, the timberland wealth measure has 

generally shown an upward trend since 1952 and is projected to increase in the 

future. Overall, the analysis by Haynes et al. (2001) suggests that the future outlook 

at a macroscale is one of stability or increases in timberland wealth, reflecting in 

part some forest area indicators.

These results show that there has been a general decline in many of the indicators characterizing conservation of biological diversity (criterion 1) and maintenance of productive capacity (criterion 2) but that this decline has slowed in the 

1990s and is expected to stabilize in the future. At the same time, measures of 

socioeconomic benefits (criterion 6) have shown increases, suggesting that whereas 

in the period 1950–89 there were tradeoffs between ecological conditions and 

economic benefits, changes in public attitudes, improving forest management, and 

increased productivity of forest lands resulted in greater balance by the 1990s. 

For example, from a timber supply perspective, increases in growing-stock inventories have offset fragmentation and parcelization and have slowed the shift from 

softwoods to hardwoods. In terms of magnitude of change, some of the greatest 

changes took place between 1976 and 1986 and involved increased harvests, especially of hardwoods for pulpwood and fuelwood.

Forest cover 

projections were 

one input used to 

examine broad-scale 

tradeoffs, compatible 

production, and the 

integrative nature of 

forest ecosystems.
73

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

The results also show an apparent contradiction. That is, what causes inventory to keep increasing when growth is about equal to or less than harvest? The 

answer lies in the proportion of the volume less than 5 inches in diameter that is not 

included in the reported volume of inventory (Smith et al. 2001), which includes the 

increasing area of relatively fast-growing plantations, as for the planted pine type 

in the South. Periods when the proportion of southern softwood inventory less than 

5 inches is relatively high include this decade and the 2030 decade. Not apparent 

in these national summaries are regional differences. For example, much of the 

increase in inventories and proportion of softwoods comes in western softwood 

species whereas most of the increase in harvest comes from southern pines, especially from pine plantations. 

The various series also suggest that we are seeing an aging of the forests as 

more timber harvest is obtained from planted acres and less from naturally regenerated forests. Overall, most timber types remain relatively stable after some initial 

declines in the 1950s and 1960s. The results also show that although fragmentation has emerged as a natural resource issue (e.g., Alig et al. 2000b; Butler et al., in 

press), it is not expected to escalate as an issue in proportion to the amount of area 

harvested. That is not to say that its importance will diminish as a land use issue, 

with perhaps more important impacts for wildlife habitat in some cases. United 

States timber consumption continues to increase as a function of population growth 

but per capita consumption falls slightly. 

These results have positive implications for the contribution of U.S. forests to 

global carbon cycles (criterion 5). In general, U.S. forest management has resulted 

in increasing total levels of carbon storage (Birdsey et al. 2001), and forest inventory levels are projected to increase by 42 percent over the next 50 years (Haynes 

2003). Projected changes in forest inventories on timberland are the net result of 

increments from growth and reductions owing to timber harvests, and net changes 

in the forest land base. For the United States as a whole, total softwood inventories 

are projected to increase about 53 percent by 2050. This increase reflects the recent 

declines in harvests and stable growth on public timberlands, growth in excess of 

harvest on private timberlands, and slowing conversions of private forest land to 

other uses. An important part of the softwood inventory growth is from young, 

rapidly growing southern pine and Douglas-fir plantations. The U.S. hardwood 

inventory is projected to increase in volume by 28 percent by 2050. Although 

overall hardwood growth is relatively stable, a major expansion in inventories in 

the North will offset a decline in the South (Haynes 2003). 
74

General Technical Report PNW-GTR-613

It is important that future discussions about “sustainability” and any policy 

actions be viewed within the context of existing resource conditions, supplies, and 

demands and with some expectation of future trends. Haynes et al. (2001) argue 

that the sustainability debate will progress when the debate shifts away from twodimensional arguments about the environment-versus-jobs tradeoffs to one that 

addresses strategic questions about the compatibility of wood production with 

ecological and socioeconomic goals. The efforts by Haynes et al. (2001) drawing 

upon the RPA timber assessment represent one source of information on the status 

and trends of renewable forest and rangeland resources in the United States; however, they do not explicitly consider sustainability options and issues in other 

sectors, such as agriculture or energy. Another caveat is that although there are a 

number of criteria and indicators identified in the Montreal Process, not all of these 

indicators can be currently addressed owing to lack of available data. Some information was available for most indicators, but data were completely lacking for 

others. In many cases, data that were available had been collected only in recent 

years, making it impossible to determine trends, or data had not been measured in 

all locations by using consistent definitions or methodologies. These data problems 

made it inappropriate or impossible to draw conclusions.

With respect to timber production sustainability, the RPA timber assessment 

indicated that the U.S. forest sector has the potential to sustain current timber harvest amounts at the national level, with stable to declining softwood log prices 

in the long term (Haynes 2003). Private timberlands have the biological potential 

to provide larger quantities of timber on a sustainable basis than they do today, but 

additional investments in tree planting and timber management intensification 

would be required.

As a key driver in forest type transitions on private lands, the volume of U.S. 

timber harvest since 1952 has risen by nearly 67 percent. This has been accompanied by growing timber inventories on both public and private lands (Haynes 2003). 

In recent years, the United States has consumed nearly 18 billion cubic feet per year 

of newly harvested roundwood of all types and from all geographic sources. For 

softwoods, 85 percent comes from domestic harvests. The United States has been a 

modest net exporter of hardwood. 

With the United States relying significantly on softwood lumber imports, 

trade issues can affect areas of forest cover types in the country. Approximately 

17 billion board feet of softwood lumber were imported from Canada in 1997. 

Harvest restrictions in Canada were put in place in some areas of coastal and interior British Columbia in the early 1990s (Canadian Forest Service 1999). Future 

As a key driver in 

forest type transitions 

on private lands, the 

volume of U.S. timber 

harvest has risen by 

67 percent since 1952.
75

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

timber harvests in Canada may be limited by allowable timber harvest limits and 

may be further influenced by softwood lumber trade agreements between the 

United States and Canada. 

Looking at future harvests, we link our modeling of forest cover changes to 

other modeling in the 2001 RPA timber assessment (Haynes 2003). Most of the U.S. 

timber harvest (80 percent in 1997) takes place in the East. Most of the expected increase in harvest will come from managed stands, primarily in the South. By 2050, 

about 60 percent of the softwood timber harvest from private timberlands will come 

from plantations, both in the South and Pacific Northwest West subregion, which 

occupy about 30 percent of the softwood timberland area and less than 20 percent 

of the total timberland area. 

The plantation area is expected to increase most in the South, which overall has 

about 10 times as much private timberland as the Pacific Northwest. Demand for 

pulpwood is important, as use of softwood pulpwood from southern pine plantations is expected to increase. With lumber and plywood composing a decreasing 

share of total forest products output, virtually all of the projected increase in U.S. 

timber harvest is in nonsawtimber trees—trees used for oriented strand board or 

paper and paperboard. The overall share of timber harvest from nonsawtimber 

will increase from 44 percent in 2000 to 66 percent by 2050. For the most part, age 

structure of forests will shift toward a greater proportion of acres in sawtimber with 

the exception of decreasing sawtimber acres for private hardwood timberland in the 

South and for private softwood timberland in the West, although in the West, the 

sawtimber proportion will increase after 2020. The use of recycled paper more than 

doubled between 1978 to 1993, along with increasing demand for paper products. 

Along with other timber supply and demand factors, recycling can contribute to 

changes in timber prices and can affect demand for pine plantations and other forest 

investments. 

United States forests will continue to change in structure and composition, 

most strikingly in terms of expanded pine plantation area in the South, increased 

age and density of forests on public lands (primarily in the West), and increased 

timber harvests in the South. Planted pine area in the South will increase by about 

40 percent by 2050. This is tied in part to the increased timber harvests in the 

South, which provide increased opportunities for reforestation after harvest. Expansion of the planted pine area will result in more timber from planted sources, 

allowing more naturally regenerated forests to be used in other ways. Some of these 

include public timberland, which on average will grow older and more dense. For 

example, area of timberland with trees older than 150 years in the National Forest 

System is expected to more than double by 2050. 

United States forests 

will continue to change 

in structure and 

composition; while 

species composition 

of U.S. forests will shift 

toward softwoods in 

the South, hardwoods 

will continue to 

dominate the 

regional landscape. 
76

General Technical Report PNW-GTR-613

In contrast to pine plantations, hardwood forest types in the South have lower 

rates of growth, less intensive forms of timber management, and expected declines in the area available for timber production (Haynes 2003). The knowledge 

of intensive hardwood silviculture is not as well developed as for softwoods, and 

silvicultural activities in hardwood stands are complex owing to the relative diversity of trees and forest species. In addition, many hardwood forests are in small 

ownership parcels, held in many cases by NIPF owners with various land management objectives. The overall area of hardwood forests in the South is projected 

to decline 7 percent through conversion to other forest types (predominantly 

softwoods), losses to urban and developed uses, and reservations for nontimber 

purposes. These projections suggest a future in which recent concerns about the 

broad-scale consequences of increasing timber production from Southern hardwood forests, such as loss of understory plants, noncommercial tree species, and 

wildlife habitat (e.g., Flather et al. 1999), will continue or intensify (Haynes 2003). 

Summary, National Overview

Key findings from the 2001 RPA timber assessment include that human impacts 

are responsible for many of the changing land conditions, in part owing to increasing population and increased demand for wood products. Loss of forest cover is 

due primarily to population expansion. From 1982 to 1997, more than one-third of 

the land converted to urban or developed uses was forested. Consumption of forest 

products in the United States will increase over the next 50 years but at a slower 

rate than in the past, rising 40 percent by 2050. More U.S. wood is being grown 

than is harvested, a trend that is expected to continue even as wood production 

and consumption increase substantially in the United States (Haynes 2003).

Over the next 50 years, most of the increase in the Nation’s timber harvest is 

projected in the East, and especially on NIPF timberlands in the South (Haynes 

2003). Plantations of softwood species will play an important role in future domestic timber harvest expansion. With this, the species composition of U.S. forests 

will shift toward softwoods in the South; however, hardwoods will continue to 

dominate the regional landscape, but related ecosystems may face increasing pressure because of land use conversions, timber production, and other disturbances. 

Species composition will move more toward hardwoods in the North and will remain largely unchanged in other regions. The changes in species composition are 

not large, as measured in terms of the percentage of total timberland area in each 

region. Diversity indices that combine information on both age and forest types 

exhibit limited change over the projection period (1997 to 2050) for the United 

States as a whole (Haynes 2003). 

The growing 

importance of 

nontimber forest 

goods and services, 

such as water, is 

increasing as human 

population increases, 

and forest cover often 

plays a critical role in 

providing such goods 

and services. 
77

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Land cover change is a widespread and significant process. In many cases, it is 

driven by human actions, and in many cases it also affects humans. United States 

trends are part of worldwide trends toward more timber production from managed 

forests, including more plantations, so that timely broad-scale reassessments and 

up-to-date data are important for effective policy analysis. In addition, the importance of nontimber forest goods and services, such as water, is increasing as population increases, and forests often play a critical role in providing those goods and 

services. 

Acknowledgments

We appreciate the assistance of several anonymous reviewers and Anne Marie Ammon, Marge Victor, Xioping Zhou, and the regional Forest Inventory and Analysis 

units of the USDA Forest Service. 

Metric Equivalents

When you know: Multiply by: To get:

Feet 0.3048 Meters

Cubic feet .0283 Cubic meters

Acres .4047 Hectares

References

Adams, D.M.; Haynes, R.W. 1996. The 1993 timber assessment market model: 

structure, projections, and policy simulations. Gen. Tech. Rep. PNW-GTR-368. 

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

Research Station. 58 p.

Ahn, S.; Plantinga, A.; Alig, R. 2001. Historical trends and projections of land 

use for the South-Central United States. Res. Pap. PNW-RP-530. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 20 p. 

Ahn, S.; Plantinga, A.; Alig, R. 2002. Determinants and projections of land use 

for the South-Central United States. Southern Journal of Applied Forestry. 26(2): 

78–84.

Alig, R. 1985. Modeling forest acreage changes in forest ownerships and cover 

types in the Southeast. Res. Pap. RM-260. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment 

Station. 14 p.
78

General Technical Report PNW-GTR-613

Alig, R. 2003. U.S. landowner behavior, land use and land cover, and climate 

change mitigation. Silva Fennica. 37(4): 511–527.

Alig, R.; Adams, D.; Chmelik, J.; Bettinger, P. 1999. Private forest investment 

and long-run sustainable harvest volumes. New Forests. 17: 307–327. 

Alig, R.; Adams, D.; Ince, P.; McCarl, B. 2000a. Economic potential of shortrotation woody crops on agricultural land for pulp fiber production in the United 

States. Forest Products Journal. 50(5): 67–74.

Alig, R.; Adams, D.; McCarl, B. 2002a. Projecting impacts of global change on 

the U.S. forest and agricultural sectors and carbon budgets. Forest Ecology and 

Management. 169: 3–14. 

Alig, R.; Butler, B. [In press]. Projecting large-scale area changes in land use and 

land cover for terrestrial carbon analyses. Environmental Management.

Alig, R.; Butler, B.; Swenson, J. 2000b. Forest fragmentation and national trends 

in private forest lands in the United States: preliminary findings from the 2000 

Renewable Resources Planning Act assessment. In: Sampson, N.; DeCoster, 

L., eds. Proceedings, forest fragmentation 2000. Washington, DC: American 

Forests: 34–47. 

Alig, R.; Haynes, R. 2002. Sustainable forest management and land use changes. 

In: Proceedings of the 2001 national convention of the Society of American 

Foresters. Washington, DC: Society of American Foresters: 116–126.

Alig, R.; Hohenstein, W.; Murray, B.; Haight, R. 1990a. Changes in area 

of timberland in the United States, 1952–2040, by ownership, forest type, 

region, and state. Gen. Tech. Rep. SE-64. Asheville, NC: U.S. Department of 

Agriculture, Forest Service, Southeastern Forest Experiment Station. 34 p.

Alig, R.; Kline, J.; Lichtenstein, M. 2004. Urbanization on the U.S. landscape: 

looking ahead in the 21st century. Landscape and Urban Planning. 69(2–3): 

219–234.

Alig, R.; Knight, H.; Birdsey, R. 1986. Recent area changes in Southern forest 

ownerships and cover types. Res. Pap. SE-260. Asheville, NC: U.S. Department 

of Agriculture, Forest Service, Southeastern Forest Experiment Station. 10 p.

Alig, R.; Lee, K.; Moulton, R. 1990b. Likelihood of timber management on 

nonindustrial private forests: evidence from research studies. Gen. Tech. 

Rep. SE-60. Asheville, NC: U.S. Department of Agriculture, Forest Service, 

Southeastern Forest Experiment Station. 17 p.
79

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Alig, R.; Mills, J.; Butler, B. 2002b. Private timberlands: growing demands, 

shrinking land base. Journal of Forestry. 100(2): 32–37.

Alig, R.; Mills, T.; Shackelford, R. 1980. Most soil bank plantings in the South 

have been retained: some need follow-up treatments. Southern Journal of 

Applied Forestry. 4: 60–64.

Alig, R.; Plantinga, A.; Ahn, S.; Kline, J. 2003. Land use changes involving 

forestry in the United States: 1952 to 1997, with projections to 2050. Gen. Tech. 

Rep. PNW-GTR-587. Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 92 p.

Alig, R.; Wear, D. 1992. Changes in private timberland: statistics and projections 

for 1952 to 2040. Journal of Forestry. 90(5): 31–36. 

Alig, R.; Wyant, J. 1985. Projecting regional area changes in forestland cover in 

the U.S.A. Ecological Modelling. 29: 127–134.

Alig, R.; Zheng, D.; Spies, T.; Butler, B. 2000c. Forest cover dynamics in the 

Pacific Northwest west side: regional trends and projections. Res. Pap. PNWRP-522. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 22 p.

American Forest and Paper Association [AF&PA]. 1999. Survey of member 

firms. 44 p. Unpublished document. On file with: R. Alig, Pacific Northwest 

Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331. 

Birdsey, R.; Alig, R.; Adams, D. 2001. Mitigation options in the forest sector to 

reduce emissions or enhance sinks of greenhouse gases. In: Joyce, L.; Birdsey, 

R., eds. The impacts of climate change on America’s forests. Gen. Tech. Rep. 

RMRS-GTR-59. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station: 112–131. Chapter 8.

Birdsey, R.; van Hees, W.; Beltz, R. 1981. Pine regeneration in southwest 

Arkansas. Res. Pap. SO-165. New Orleans, LA: U.S. Department of Agriculture, 

Forest Service, Southern Forest Experiment Station. 10 p.

Boyce, S.; McClure, J.; Sternitkze, H. 1975. Biological potential for the loblolly 

pine ecosystem east of the Mississippi River. Res. Pap. SE-142. Asheville, NC: 

U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment 

Station. 27 p.
80

General Technical Report PNW-GTR-613

Butler, B.; Swenson, J.; Alig, R. [In press]. Forest fragmentation in the Pacific 

Northwest: quantification and correlations. Forest Ecology and Management. 

Canadian Forest Service. 1999. The state of Canada’s forests: 1998. Ottawa, ON. 

67 p.

Cooper, C. 1960. Changes in vegetation, structure, and growth of Southwestern 

pine forests since White settlement. Ecological Monographs. 30(2): 129–164.

Covington, W.; Everett, R.; Steele, R. [et al.]. 1994. Historical and anticipated 

changes in forest ecosystems of the inland West of the United States. Journal 

of Sustainable Forestry. 2(1/2): 13–63. 

Covington, W.; Moore, R. 1994. 1994: Southwestern ponderosa pine forest 

structure: changes since Euro-American settlement. Journal of Forestry. 

92: 39–47. 

Di Gregorio, A.; Jansen, L. 1998. Land cover classification system: classification 

concepts and user manual [Abstract]. http://www.fao.org/WAICENT/FAOINFO/

SUSTDEV/EIdirect/EIre0062.htm. (May 12, 2000).

Dubois, M.; McNabb, K.; Straka, T. 1999. Costs and cost trends for forestry 

practices in the South. Forest landowner manual 32nd ed. Forest Landowner. 

58(2): 3–8.

Flather, C.; Brady, S.; Knowles, M. 1999. Wildlife resource trends in the United 

States. Gen. Tech. Rep. RMRS-GTR-33. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 79 p.

Griffith, D.; Alerich, C. 1996. Forest statistics for Maine, 1995. Resour. Bull. 

NE-135. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeast 

Forest Experiment Station. 134 p. 

Haynes, R., tech. coord. 2003. An analysis of the timber situation in the United 

States: 1952 to 2050. Gen. Tech. Rep. PNW-GTR-560. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

254 p.

Haynes, R.; Adams, D.; Mills, J. 1995. The 1993 RPA timber assessment 

update. Gen. Tech. Rep. RM-GTR-259. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment 

Station. 66 p. 
81

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Haynes, R.; Barbour, J.; Stevens, J. 2001. Criteria and indicators for sustainable 

forest management in the U.S.A. national and regional level. In: Krishnapillay, 

B.; Soepadmo, E.; Arshad, N.L. [et al.], eds. Forests and the role of research: 

21st International Union of Forest Research Organizations world congress. Kuala 

Lumpur, Malaysia: International Union of Forest Research Organizations: 

238–250. Vol. 1.

Hessburg, P.; Salter, R.; Richmond, M.; Smith, B. 2000. Ecological subregions 

of the interior Columbia basin, USA. Applied Vegetation Science. 3(2): 163–180.

Ince, P. 1999. Long-range outlook for U.S. paper and paperboard demand, 

technology, and fiber supply-demand equilibria. In: Proceedings of the Society 

of American foresters 1998 national convention. Bethesda, MD: Society of 

American Foresters: 330–343. 

Ince, P. 2000. Outlook for U.S. paper and paperboard sector and wood fiber 

supply in North America. In: UN-ECE/TIM/DP/15 Geneva timber and forest 

discussion papers 2000. Geneva, Switzerland: United Nations Publications: 

24–37. Chapter 5. 

Irland, L.; Adams, D.; Alig, R. [et al.]. 2001. Assessing socio-economic impacts 

of climate change on U.S. forests, wood products markets, and forest recreation. 

BioScience. 51(9): 753–764.

Johnson, M. 1996. Changed Southwest forests: resource effects and management 

remedies. In: Diverse forests, abundant opportunities, and evolving realities. 

Proceedings of the 1996 Society of American Foresters national convention. 

Bethesda, MD: Society of American Foresters: 109–117.

King, S.; Butler, B. [In press]. Forest ownership in the United States. In: Beevers, 

M., comp. ed.; Systems analysis in forestry. Gen. Tech. Rep. Fort Collins, CO: 

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

Station.

Kline, J.; Alig, R. 2001. A spatial model of land use change for western 

Oregon and western Washington. Res. Pap. PNW-RP-528. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 24 p.

Kline, J.; Butler, B.; Alig, R. 2002. Tree planting in the South: history and 

projections. Southern Journal of Applied Forestry. 25: 14–25. 

Knight, H. 1973. The pine decline. Journal of Forestry. 85(1): 25–28.
82

General Technical Report PNW-GTR-613

Knight, H. 1978. The South is losing its pines. Forest Farmer. (Nov.–Dec.): 10–12.

Knight, H. 1985. Southern U.S. timber supplies. In Proceedings of the 3rd North 

American International Institute for Applied Systems Analysis meeting. 

Victoria, BC: University of British Columbia: 27–37.

Kurtz, W.; Noweg, T.; Moulton, R.; Alig, R. 1996. Retention, condition, and land 

use implications of tree plantings established under federal cost-share programs. 

In: Baughman, M., ed. Learning from the past, prospects for the future: 

proceedings of a symposium on nonindustrial private forests: St. Paul, MN: 

Minnesota Extension Service, University of Minnesota: 348–356. 

Mauldin, T.; Plantinga, A.; Alig, R. 1999a. Determinants of land use in Maine 

with projections to 2050. Northern Journal of Applied Forestry. 16(2): 82–88.

Mauldin, T.; Plantinga, A.; Alig, R. 1999b. Land use in the Lake States region: 

an analysis of past trends and projections of future changes. Res. Pap. PNWRP-519. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 24 p. 

McWilliams, W.; Moulton, R. 1991. Reforestation of nonindustrial private pinesite timberland in the South-Central United States. In: Stoll, J., ed. Proceedings 

of the 46th annual meeting of the soil and water conservation society. Lexington, 

KY: [Publisher unknown]: 23–28.

Mills, J.; Zhou, X. 2003. Projecting national forest inventories for the 2000 

RPA timber assessment. Gen. Tech. Rep. PNW-GTR-568. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

58 p.

Moffat, S.; Cubbage, F.; Cascio, A.; Sheffield, R. 1998. The future of forest 

management on NIPF lands in the South: results of an expert opinion survey. 

In: Abt, K.; Abt, R., eds. Proceedings of the Southern forest economics workers 

meeting. Research Triangle Park, NC: North Carolina State University: 17–24. 

Moulton, R. 1999. An update: changes abound in forestry cost-share assistance 

programs. Tree Farmer. 18(5): 10–15. 

Moulton, R.; Dicks, M. 1990. Sleeping giant. In: Zhang, D., ed. Proceedings of the 

1989 Southern forest economics workshop. Auburn, AL: School of Forestry and 

Wildlife Sciences, Auburn University: 153–156.
83

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Moulton, R.; Hernandez, R. 1999. Tree planting in the United States 1994. 

Washington, DC: U.S. Department of Agriculture, Forest Service, State and 

Private Forestry, Cooperative Forestry. 29 p.

Plantinga, A.; Ahn, S. 2002. Efficient policies for environmental protection: an 

econometric analysis of incentives for land conversion and retention. Journal of 

Agricultural and Resource Economics. 27(1): 128–145.

Plantinga, A.; Mauldin, T.; Alig, R. 1999. Land use in Maine: determinants of 

past trends and projections of future changes. Res. Pap. PNW-RP-511. Portland, 

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

Station. 20 p.

Siry, J.; Cubbage, F. 2002. A survey of timberland investment management 

organizations forestland management in the South. In: Zhang, D., ed. 

Proceedings of the 2001 Southern forest economics workshop. Auburn, AL: 

School of Forestry and Wildlife Sciences, Auburn University: 153–156.

Smith, W.B.; Vissage, J.; Sheffield, R.; Darr, D. 2001. Forest resources of the 

United States, 1997. Gen. Tech. Rep. NC-219. St. Paul, MN: U.S. Department of 

Agriculture, Forest Service, North Central Research Station. 190 p.

Sohngen, B.; Alig, R. 2000. Mitigation, adaptation, and climate change: results 

from recent research on U.S. timber markets. Environmental Science and Policy. 

3: 235–248. 

Stearns, F. 1997. Physical environment supporting Lake States forests. In: 

Vasievich, J.M.; Webster, H.H., eds. Lake States regional forest resources 

assessment: technical papers. Gen. Tech. Rep. NC-189. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North Central Forest Experiment 

Station: 1–7.

United Nations Conference on Environment and Development. 1993. Agenda 

21: the United Nations programme of action from Rio. New York: Department of 

Public Information. 39 p.

U.S. Department of Agriculture, Forest Service. 1982. An assessment of the 

forest and rangeland situation in the United States. Forest Resource Rep. 22. 

Washington, DC. 499 p.

U.S. Department of Agriculture, Forest Service. 1988. The South’s fourth forest: 

alternatives for the future. Forest Resource Rep. 24. Washington, DC. 512 p.
84

General Technical Report PNW-GTR-613

U.S. Department of Agriculture, Forest Service. 1989. An analysis of the land 

base situation in the United States: 1989-2040. Gen. Tech. Rep. RM-181. Fort 

Collins, CO: Rocky Mountain Forest and Range Experiment Station. 76 p.

U.S. Department of Agriculture, Forest Service. 2001. 2000 RPA assessment of 

forest and rangelands. FS-687. Washington, DC: U.S. Department of Agriculture, 

Forest Service. 78 p. 

U.S. Department of Agriculture, Natural Resources Conservation Service 

[NRCS]. 2001. National resource inventory. Washington, DC. 178 p.

Vasievich, J.M.; Webster, H.H., eds. 1997. Lake States regional forest resources 

assessment: technical papers. Gen. Tech. Rep. NC-189. St. Paul, MN: U.S. 

Department of Agriculture, Forest Service, North Central Forest Research 

Station. 172 p.

Wear, D.; Greis, J. 2002. Southern forest resource assessment: summary of 

findings. Journal of Forestry. 100(7): 6–15.

Wyant, J.; Alig, R.; Bechtold, W. 1991. Forest type changes by physiographic 

region. Forest Ecology and Management. 45: 23–31. 

Zheng, D.; Alig, R. 1999. Changes in the nonfederal land base involving forestry 

in western Oregon. Res. Pap. PNW-RP-518. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 22 p.
85

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Appendix 1: Forest Cover Database and Forest 

Cover Area Studies

We document the major forest cover database that we drew from for this study. 

“Land use” and “land cover” are sometimes used interchangeably, but the two 

terms are not the same. Land use is the purpose to which land is put by humans, 

e.g., protected areas, forestry for timber products, plantations, row-crop agriculture, 

pastures, or human settlements. Land cover is the observed (bio)physical cover on 

the Earth’s surface (Di Gregorio and Jansen 1998), e.g., oak-hickory forest. This 

report pertains to land cover, whereas Alig et al. (2003) document land use changes 

involving U.S. forests. 

Data Sources

Forest cover data are collected by various agencies for a variety of purposes and 

from various sources, including remotely sensed data and that from ground-based 

inventories. Our need was for a set of forest cover data that were consistent nationwide with respect to statistical data-collection methods, scope, and a variety 

of other characteristics, e.g., linkage to timberland and ownerships classifications. 

Thus, we drew upon the Forest Inventory and Analysis (FIA) data assembled to 

support the 2000 Forest and Rangeland Renewable Resources Planning Act (RPA) 

assessment by the USDA Forest Service (e.g., Smith et al. 2001). 

The FIA surveys conducted by the USDA Forest Service are designed to 

provide objective and scientifically credible information on key forest attributes, 

such as forest stocks, growth, harvest, and mortality. Related data are collected on 

region, forest ownership category (e.g., forest industry vs. nonindustrial private 

forests [NIPF]), and cover type (e.g., oak-hickory), by using a sample of more than 

70,000 permanent plots. The FIA inventories provide consistent forest inventory 

data for the Nation back to 1953 (Smith et al. 2001). Originally, FIA had established 

a fixed grid of points across the United States, with the intention of remeasuring 

forest attributes on these plots every 5 to 15 years. Since the 2000 RPA assessment 

work, FIA has moved to an annual inventory system. The FIA inventories measure 

approximately one field plot for every 6,000 acres of forest land in most regions.

The FIA inventories in conjunction with the RPA assessments have now 

resulted in four related databases: (a) East-wide; (b) West-wide standard forest 

inventory databases; (c) national timber products output database, and (d) a national 

summary database that draws upon the others and also incorporates other data from 

the U.S. Bureau of the Census (total land area, population, etc.). The FIA inventory 

data are gathered by using photointerpretation and ground truthing on a systematic 

sample of plots defined as pinpoints on the ground. These data include land use and 
86

General Technical Report PNW-GTR-613

ownership characteristics of sample plots, among other data, providing consistent 

and complete coverage for all private timberlands. Inventories by FIA were used 

for a description of initial conditions and use in projections because a systematic 

approach and consistency are prime concerns. 

Forest cover types in FIA surveys are classified based on the forest species 

forming a plurality of the live-tree stocking (Smith et al. 2001). A forest type group 

is a combination of forest cover types that share closely associated forest species or 

site requirements and are generally combined for brevity of reporting. An example 

is the white-red-jack pine cover type group, comprising forests in which eastern 

white pine (Pinus strobus L.), red pine (Pinus resinosa Ait.), or jack pine (Pinus 

banksiana Lamb.), singly or in combination, compose a plurality of the stocking. 

Common associates include hemlock (Tsuga spp.), aspen (Populus spp., and maple 

(Acer spp.). Forest cover types identified in the FIA surveys are classified according 

to 22 types used in this study, with 10 in the East and 12 in the West. 

One supplementary source of data was timber resource data for industry lands 

from a survey conducted by the American Forest and Paper Association (AF&PA 

1999). The numbers compiled by the AF&PA include forest area owned in a aregion 

by member firms and were used to calculate a final harvest probability matrix. We 

weighted AF&PA and FIA-based final harvest matrices so that a heavier weight was 

given to the AF&PA inputs because their values reflect future intentions, whereas 

the FIA values reflect past behaviors. We had AF&PA inputs for three major timber 

supply regions and used these weights for the AF&PA matrix for forest industry 

lands in the respective regions: South—0.75, Lake States subregion—0.60, and 

Pacific Northwest West side subregion—0.75. 

Another supplementary source of data was final harvest matrix data for NIPF 

timberlands in the South, from a survey of state forestry agencies (Moffat et al. 

1998). We weighted the state forestry agency and FIA-based final harvest matrices 

equally, so that for the South, the weight was 0.5 for each source. Similar surveys 

were not available for other regions; in those cases, the FIA weight is 1. 

Methods Used to Project Area Changes in Forest Cover Types

Empirical methods used to project area changes for forest cover types on private 

timberland differ by region of the United States. Methods differ depending on the 

likelihood that area changes affect forests, the likely policy relevance of forest area 

changes, and the availability of data, especially time series of forest cover type data 

with which to develop models of forest cover change. Next, we first summarize 

the general approach, and then we provide more details on the approach used for 
87

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

the South that had relatively longer time series of comprehensive data on forest 

cover types. 

The analysis of forest cover dynamics was conducted by categorizing timberland by region, ownership, forest cover, and disturbance categories at two points 

in time. The regions are those used by the RPA assessment (fig. 1).

Area changes for forest types on a particular ownership can result from four basic sets of activities: afforestation, deforestation, shifts among forest cover types on 

retained timberland, and ownership exchanges. In contrast to ecological processes, 

land use changes and disturbances can differ significantly by type of private ownership. Ownership changes in the timberland base may result in new owners with 

different land management objectives or different access to types of technology or 

available resources to invest in forest management. Changes in the areas of forest 

types often reflect differences in land management objectives among owners and 

indicate the differential influence of natural and human-caused management forces. 

We modeled forest type transitions based on empirical analysis of data from 

remeasured FIA survey plots. Data pertaining to ownership, forest cover, land use, 

and forest productivity from the two most recent surveys in each state were used to 

calculate the forest type area vectors and forest type transition matrices (e.g., Alig 

and Wyant 1985). 

Projections of such area changes for major forest types take into account the 

likelihood of timber harvest and forest successional forces (Alig and Wyant 1985). 

Forest type transitions for an aggregate grouping of timberland (by a stratum 

representing a specific region and ownership) are conditional on three disturbance 

types—no harvest, final or clearcut harvest, and partial harvests. Within the system 

of RPA models (fig. 49), projected harvest information is provided by the overall 

TAMM/NAPAP/ATLAS/AREACHANGE modeling system (e.g., Adams and 

Haynes 1996, Alig et al. 2002b) from the 2000 RPA timber assessment (Haynes 

2003).

Forest cover projections are made with Markov chain models (Alig and Wyant 

1985), which use timber harvest probabilities from the TAMM/NAPAP/ATLAS 

portion of the modeling system for harvest disturbances. Harvest estimates lead 

to adjustments in timber inventories (and broad-scale vegetation conditions) given 

changes in forest growth and timberland loss and gain. The volume of available 

timber inventory is then fed back to both the solid wood and paper and board 

models as a major determinant of stumpage supply. For other disturbance categories 

(e.g., windthrow), primary data sources were USDA Forest Service’s FIA periodic 

forest surveys, AF&PA (1999) survey data, and a survey of state foresters regarding 

NIPF timber management tendencies documented by Moffat et al. (1998).
88

General Technical Report PNW-GTR-613

Changes in area among forest cover types affect both the nature and volume 

of timber available from forests. For example, decreases in timber production can 

occur when commercial species are replaced by noncommercial species. Area 

change projections by forest management type were based on assumptions about 

the probability that a particular acre will receive a certain type of management or 

disturbance and the associated probabilities that an acre so managed will remain in 

the same forest type or will make the transition to other forest types (fig. 50). 

x

acres

P (final harvest) - 0.10 0 P (OS)

P (WH)

P (RA)

P (DF)

P (OH)

0.01

0.95

0.03

0.01

0.01 P (OS)

P (WH)

P (RA)

P (DF)

P (OH)

0.03

0.73

0.06

0.17

0 P (OS)

P (WH)

P (RA)

P (DF)

P (OH)

0

0.86

0.07

0.07

P (none) - 0.74

P (miscellaneous disturbance) - 0.16

DF = Douglas-fir

WH = westerm hemlock

OS = other softwoods

RA = red alder

OH = other hardwoods

Example: Initial forest type—

 Douglas-fir on nonindustrial 

 private forest ownership

Figure 50—Example of probability tree for forest type transitions on nonindustrial private forest 

timberlands in the Pacific Northwest West subregion (Alig et al. 2000c). 
89

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Final harvest, partial harvest, and no harvest are the disturbance categories. A 

final harvest is the removal of trees from a stand that results in a residual stand that 

is not manageable for timber production. Final harvests include clearcuts, shelterwoods, and seed tree silvicultural treatments. A partial harvest is a human activity 

that removes timber from a stand but leaves enough trees to allow management of 

the residual stand for timber production. 

Forest cover dynamics also can be influenced, in part, by other humans. Humancaused disturbances typically occur more frequently than natural ones on private 

timberlands, sometimes with a frequency that is an order of magnitude higher (e.g., 

Alig 1985, Alig et al. 2000c). Afforestation, such as the conversion of an agricultural 

field to a conifer plantation, is one important example. Deforestation, when land is 

converted from forest land to nonforest (e.g., a residential development), is another 

example of human-caused disturbances that can have significant influences on forest 

composition. Human-caused disturbances can interact with natural disturbances 

(e.g., insects) and also can set back successional trends. Successional processes involving recruitment, growth, reproduction, and mortality are involved in determining inter- and intraspecies competition and forest stand dynamics.

Example: Projection Model for the South Region

Area changes for forest cover type changes in the South have been some of the more 

important ones between 1953 and 1997. The South had less than 3 million acres of 

planted pine before 1950, and since then more than 25 million acres of pine plantations have been established on previously nonforested lands or converted from other 

forest types (Alig et al. 2002b). 

Given the importance of the region for forest industry, supplementary data were 

obtained from a forest industry survey. The AF&PA (1999) conducted a survey of 

future forest management intentions of forest industry landowners. These survey 

data were used to construct a final harvest transition matrix of forest covers for 

forest industry timberlands, described below. For NIPF timberlands, state forestry 

agencies in the South were surveyed to provide supplementary data (Moffat et al. 

1998).

Other inputs to the southern modeling were exogenous land use projections 

(Alig et al. 2003) and exogenous harvest probabilities (Haynes 2003). Land use 

changes involving afforestation and deforestation affect areas of forest cover types 

over time (fig. 51). Deforestation is most often caused by conversion to other land 

uses. This contrasts to timber harvests as part of typical forestry activities, because 

timber harvests are often followed by regeneration back to forest (Alig 1985). The 

land use projections of timberland area by region and ownership through 2050 were 
90

General Technical Report PNW-GTR-613

based on econometric analyses (e.g., Ahn et al. 2001). Harvest probabilities were 

calculated through an iterative process involving the TAMM/NAPAP/ATLAS/

AREACHANGE modeling system (fig. 49) (Haynes 2003). 

Forest cover dynamics were modeled by using a series of forest cover transition 

matrices and disturbance probability vectors (equations 1A and 1B). These three 

forest cover transition matrices and four probability vectors represent the major 

processes affecting forest composition and are a refinement of the Markov chain 

method developed by Alig (1985). Each of the matrices and vectors were calculated 

from FIA data, unless otherwise noted, and were calculated separately for each 

region and ownership group.

 Ft

 = (hFt–1)PH + (pFt–1)P

p

 + (Ft–1 – pFt–1– hFt–1)PN . (1A)

 Ft–1 = (τ

t

 – τ

t–1

)D + Ft–1 (area adjustment) . (1B)

' ' ' ' '

'

Figure 51—Designation of land uses and relations of overall land use modeling to that for cover types with the modeling system for RPA 

assessments, with example of forest cover types for the South region. 

Land 

uses

Crop 

agriculture

Pasture/range

agriculture

Private

Public

Planted 

pine

Natural

pine

Oakpine

Upland 

hardwood

Forest 

ownership

Forest types

Forest industry

Forest types

Nonindustrial

Forest

Lowland 

hardwood

Planted 

pine

Natural

pine

Oakpine

Upland 

hardwood

Lowland 

hardwood

Urban/other 

built-up
91

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

where

Ft = a vector of forest cover areas at time t,

Ft–1 = a vector of forest cover areas at time t–1 adjusted for timberland gains or 

losses,

τ = the area of timberland at time t or t–1,

D = an afforestation vector if Δτ >0 or a deforestation vector if Δτ < 0,

h = final harvest probability vector,

p = partial harvest probability vector,

PH = forest cover transition matrix following a final harvest,

P

p = forest cover transition matrix following a partial harvest, and

PN = forest cover transition matrix for nonharvested lands.

The harvest probability vectors can be interpreted as the probability of a final 

or partial harvest occurring within a given forest cover. The final harvest probability vector (h) is the proportion of a given ownership’s forest cover area in which all 

merchantable trees will be harvested in a given period. The partial harvest probability vector (p) is the proportion of a given ownership’s forest cover area that will be 

partially harvested in a given period. The final harvest and partial harvest vectors 

were calculated by dividing the area of the forest cover that was final harvested or 

partially harvested by the total area of the forest cover. All probabilities are based 

on the average remeasurement periods. 

The afforestation and deforestation vectors were calculated by dividing the area 

of a given forest cover that was either gained or lost by the total area of timberland 

that was gained or lost. The afforestation vector describes the allocation of forest 

covers among timberland that is gained from nontimberland land uses. The deforestation vector describes the allocation of forest covers among timberland that is lost 

to nontimberland land uses.

A forest cover transition matrix is a state/fate matrix that represents the probability of a given forest cover (state) remaining the same or becoming a different 

forest cover (fate) in a subsequent period. To calculate these matrices, the areas of 

each state/fate combination were first calculated with the state forest covers as rows 

and the fate forest covers as columns. For example, an element of an area matrix 

might represent the area of upland hardwood (state or row) that was converted to 

planted pine (fate or column) following a final timber harvest on NIPF lands in the 

Southeast. These area matrices were converted into probability matrices by dividing each element by the row/state total, i.e., the total area of that forest cover in the 

earlier period. 

'
92

General Technical Report PNW-GTR-613

The forest cover transition matrices for nonharvested timberlands (PN) are 

state/fate matrices with elements that are the probabilities that a given forest cover 

will remain in the same forest cover or transition into a different forest cover owing 

to succession, natural disturbance, and nonharvest human disturbance processes. 

The forest cover transition matrices for final harvested timberlands (PH) are state/

fate matrices with elements that are the probabilities that a given forest cover will 

remain in the same forest cover or transition into a different forest cover following a 

final harvest. The forest cover transition matrices for partially harvested timberlands 

(P

p

) are state/fate matrices with elements that are the probabilities that a given forest 

cover will remain in the same forest cover or transition into a different forest cover 

following a partial harvest.

The initial forest cover areas were calculated from FIA data. The acreages were 

calculated by multiplying the forest cover proportions by the total timberland area. 

The allocation (proportion) of forest covers was extracted from the FIA database 

(http://ncrs2.fs.fed.us/4801/fiadb/index.htm) by dividing the area of each forest cover 

by the summed area of all forest covers from the most recent forest inventories. The 

total timberland areas were extracted from the RPA data tables (Smith et al. 2001). 

The harvest probabilities taken from projections by the TAMM/NAPAP/ATLAS/AREACHANGE modeling system become part of the vector h in equation 

[1B]. This approach is similar to that used in the South’s Fourth Forest study (USDA 

Forest Service 1988). 

Given the importance of timber harvests in forest type transitions, feedback 

loops in our projections included incorporating disturbance probabilities and market 

price signals from the set of national timber supply models that projects timber 

prices (fig. 52) (e.g., Adams and Haynes 1996). We adjusted projections of planted 

pine area at certain time steps if subsequent projections for Southern timber prices 

were significantly higher than those used in the original model run. We drew upon 

recent elasticity estimates from the tree planting study by Kline et al. (2002), which 

give the percentage of change in planted pine area for a corresponding percentage 

of change in Southern timber prices. The response is inelastic in that the change in 

planted pine area is less than the corresponding percentage of change in Southern 

timber prices. This is true partly because private owners may alter use of other nonland inputs (e.g., fertilizer) in response to timber price changes.

An example of feedbacks involving timber prices is the case of pulpwood prices 

in the South. Pulpwood prices are influenced by the RPA projection of an increased 

supply of softwood pulpwood-size material in the South after 2010. The net effect 

is a softwood price drop after 2010, which thereby somewhat dampens incentives 
93

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Area model 

(land use)

USDA, FIA

TAMM, 

NAPAP, 

ATLAS

Timberland areas

Forest type 

transition 

probabilities

Forest type

gain probabilities

Forest type

loss probabilities

Harvest 

probabilities

Area model 

(land cover) Forest type areas

AF&PA survey

NIPF survey

Area change modeling: land cover/forest type area projections

Figure 52—Flow chart for use of major input sets in the modeling system for projecting forest cover type areas in national 

assessments.

for establishing more pine plantations. This contributes to smaller future additions 

to pine plantation area compared to the first several decades (fig. 52). Lower price 

projections in the later decades make pine plantations financially less attractive, so 

less agricultural land and area of other forest types is converted to plantations. In 

those decades, projected expansion in pine plantation area would outpace projected 

changes in timber demand, and timber prices would drop. 

The RPA model system captures interregional effects of price changes as well 

as price feedbacks each period. The South Central subregion is the likely location 

of any future increases in timberland because of net gains from land exchanges 

with agriculture (e.g., Ahn et al. 2002), whereas future reductions in timberland 

area would be concentrated in the Atlantic Coast States. The South Central subregion has more than twice the land area of the Southeast and more potential for 

expansion in pine plantation area. More than two-thirds of the future addition to 

plantation area is projected to be in the South Central subregion. Actual future 

outcomes are likely to be sensitive to relative economic returns for forestry versus 

agriculture in the region, which will be influenced by the timber price projections 

described above.
94

General Technical Report PNW-GTR-613

Future Modeling Research

As with all modeling and projection endeavors, our work has identified possible 

improvements as more data accumulate and techniques evolve. One research need 

is to investigate nonstationarity. That is, a major assumption involving the Markov 

method used in this study is that the probability matrices and vectors do not vary 

over time (i.e., it is assumed that the same driving forces that produced the observed 

probabilities will remain constant throughout the projection period) with the exception that the harvest probabilities varied in line with projections by the TAMM/

NAPAP/ATLAS modeling system. The structure of the model can be adapted to 

handle other nonstationary vectors and matrices, but we did not have satisfactory 

methods for estimating these values.

Another research need is to increasingly integrate land use and forest cover models, including consideration of forest investment. For example, in the South Central 

subregion used in this study, we tied to land use projections by Ahn et al. (2002). A 

key interface is the afforestation pathway, especially for planted pine in the South. 

More fully integrated models would aid in policy deliberations pertaining to mitigation activities for climate change concerns (Alig 2003). Expanded data pertaining 

to forest cover on nontimberland forest land and public forest land would also aid in 

climate change analyses, including compiling time series of data. 

Area trends for forest cover types also differ by major forest ownership class, 

and additional research can aid in identifying likely future changes. An example 

is that about 70 percent of timberland owned by timber investment management 

organizations in the South is planted pine, much higher than the overall percentage for the broader NIPF ownership class. A survey indicated that such institutional 

investors plan additional conversions of other forest types to pine plantations (Siry 

and Cubbage 2002); however, there is significant variation among such investors 

concerning type of forest management. Although total timberland holdings by such 

organizations was relatively small in 2000, less than 5 percent of total timberland, 

some suggest a strong growth potential (Siry and Cubbage 2002). Behavior by such 

owners is important as well for a broad array of forest-based goods and services, as 

these owners pursue a mixture of financial and conservation goals. 

Other research needs include more information on the implications of high-grading harvests on forest cover over time. A variety of timber harvest methods are used 

across the United States and can affect the species mix under some regeneration 

activities. Harvests on private timberland also are influenced at times by owners’ 

responses to institutional elements, such as partial harvesting that satisfies reforestation regulations without requiring substantial investment in active regeneration. Such 

responses need to be monitored, along with any significant shifts in forest covers. 
95

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Appendix 2: Species Diversity by Region

South

Diversity and composition of trees differed widely among forest types, although 

a few species, such as loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar 

styraciflua L.), were observed in all forest types (figs. 53–58). The species diversities (i.e., number of species) within each forest type were fairly constant across 

ownerships, but the relative species abundances varied significantly. For example, 

loblolly pine was the dominant species in the planted pine forest type across both 

private ownerships, but it accounted for 90 percent of the volume on forest industry 

timberlands, 79 percent on miscellaneous corporate timberlands,1

 and 78 percent on 

other private timberlands in the Southeast subregion.

Other important species in the planted pine forest type were slash (P. elliottii 

Engelm.) and longleaf (P. palustris P. Mill) pines. The natural pine forest type also 

was dominated by loblolly pine with 67 percent of the forest industry, 55 percent of 

the miscellaneous corporate, and 59 percent of the other private timberland volumes 

in the Southeast subregion being accounted for by this species. Longleaf, pond (P. 

serotina Michx.), and shortleaf (P. echinata P. Mill.) pines were other important 

species in the natural pine forest type. The oak-pine forest type was dominated by 

loblolly pine, oaks (Quercus spp.), sweetgum, swamp tupelo (Nyssa sylvatica var.

biflora (Walt.) Sarg.), and spruce pine (P. glabra Walt.). The upland hardwood forest 

type was dominated by oaks (especially white oak [Quercus alba L.]), sweetgum, 

yellow-poplar (Liriodendron tulipifera L.), and hickories (Carya spp.). The lowland 

hardwood forest type was dominated by swamp tupelo, red maple (Acer rubrum 

L.), sweetgum, yellow-poplar, oaks, baldcypress (Taxodium distichum (L.) Rich.), 

and ash (Fraxinus spp.).

Pacific Coast

The western hemlock–Sitka spruce forest type was dominated by western hemlock 

(Tsuga heterophylla (Raf.) Sarg.) on forest industry timberlands and was codominated by western hemlock and Sitka spruce (Picea sitchensis (Bong.) Carr.) on 

NIPF private timberlands. Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) 

and red alder (Alnus rubra Bong.) were other important species in the hemlockspruce forest type. Western redcedar (Thuja plicata Donn ex. D. Don) was the most 

common species in the other softwood forest type, but this forest type contained a 

1

 Additional Forest Inventory and Analysis data allow the nonindustrial private forest 

ownership class to be separated into miscellaneous corporate and other private classes 

(see “Glossary”) in the South. 
96

General Technical Report PNW-GTR-613

diversity of species including Douglas-fir, western hemlock, Pacific silver fir (Abies 

amabilis Dougl. ex. Forbes), grand fir (A. grandis (Dougl. ex D. Don) Lindl.), bigleaf maple (Acer macrophyllum Pursh), and red alder. Red alder was the dominant 

species of the red alder forest type with Douglas-fir, western redcedar, and bigleaf 

maple as important subdominants. The other hardwood forest type contained a 

large diversity of species including Douglas-fir, bigleaf maple, red alder, and Pacific 

madrone (Arbutus menziesii Pursh). Other hardwood and other softwood types 

were the most diverse cover types, and Douglas-fir was the least diverse (figs. 59 

and 60).
97

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

 LBP = loblolly pine

 Oak = oak species

 ST = swamp tupelo

 SG = sweetgum

 SP = slash pine

 RM = red maple

 YP = yellow-poplar

Planted pine

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

100

80

60

40

20

0

Upland hardwood

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

100

80

60

40

20

0

Lowland hardwood

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

100

80

60

40

20

0

LLP = longleaf pine

WT = water tupelo

BC = bald cypress

PP = pond pine

OH = other hardwood

OS = other softwood

Natural pine

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

100

80

60

40

20

0

Oak-pine

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

100

80

60

40

20

0

Species codes

Figure 53—Species diversity in the Southeast subregion, forest industry timberlands, 1997. 
98

General Technical Report PNW-GTR-613

Figure 54—Species diversity in the Southeast subregion, miscellaneous corporate timberlands, 1997.

LBP = loblolly pine

Oak = oak species

ST = swamp tupelo

SG = sweetgum

SP = slash pine

RM = red maple

YP = yellow-poplar

LLP = longleaf pine

WT = water tupelo

BC = bald cypress

PP = pond pine

OH = other hardwood

OS = other softwood

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

Species codes

80 Planted pine

60

40

20

0

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

80 Natural pine

60

40

20

0

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

80 Oak-pine

60

40

20

0

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

80 Lowland hardwood

60

40

20

0

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

Stand volume (mean percentage)

80 Upland hardwood

60

40

20

0
99

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 55—Species diversity in the Southeast subregion, other private timberlands, 1997. LBP Oak ST SGSP RMYP LLP WT BCPP OHOS Stand volume (mean percentage) Stand volume (mean percentage)

Planted pine Natural pine LBP Oak ST SGSP RMYP LLP WT BC

PP

OH

OS

80

60

40

20

0

80

60

40

20

0

Stand volume (mean percentage)

Oak-pine

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

80

60

40

20

0

Stand volume (mean percentage)

Lowland hardwood

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

80

60

40

20

0

Stand volume (mean percentage)

Upland hardwood

LBP

Oak

ST

SG

SP

RM

YP

LLP

WT

BC

PP

OH

OS

80

60

40

20

0

LBP = loblolly pine

Oak = oak species

ST = swamp tupelo

SG = sweetgum

SP = slash pine

RM = red maple

YP = yellow-poplar

LLP = longleaf pine

WT = water tupelo

BC = bald cypress

PP = pond pine

OH = other hardwood

OS = other softwood

Species codes
100

General Technical Report PNW-GTR-613

Figure 56—Species diversity in the South Central subregion, forest industry timberlands, 1997. 

Species codes

LBP = loblolly pine

Oak = oak species

SHP = shortleaf pine

SG = sweetgum

SLP = slash pine

BC =bald cypress

Planted pine

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

Stand volume (mean percentage)

60

40

20

0

Oak-pine

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

60

40

20

0

Lowland hardwood

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

60

40

20

0

Upland hardwood

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

60

40

20

0

Natural pine

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

60

40

20

0

LLP = longleaf pine

WT = water tupelo

Hick = hickory species

YP = yellow-poplar

OH = other hardwood

OS = other softwood
101

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 57—Species diversity in the South Central subregion, miscellaneous corporate timberlands, 1997.

Planted pine Natural pine

Oak-pine

Upland hardwood Lowland hardwood

LBP = loblolly pine

Oak = oak species

SHP = shortleaf pine

SG = sweetgum

SLP = slash pine

BC = bald cypress

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

Stand volume (mean percentage)

Stand volume (mean percentage)

Stand volume (mean percentage) Stand volume (mean percentage)

Stand volume (mean percentage)

LLP = longleaf pine

WT = water tupelo

Hick = hickory species

YP = yellow-poplar

OH = other hardwood

OS = other softwood

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

60

50

40

30

20

10

0

60

50

40

30

20

10

0

60

50

40

30

20

10

0

60

50

40

30

20

10

0

60

50

40

30

20

10

0

Species codes
102

General Technical Report PNW-GTR-613

Figure 58—Species diversity in the South Central subregion, other private timberlands, 1997.

LBP = loblolly pine

Oak = oak species

SHP = shortleaf pine

SG = sweetgum

SLP = slash pine

BC = bald cypress

LLP = longleaf pine

WT = water tupelo

Hick = hickory species

YP = yellow-poplar

OH = other hardwood

OS = other softwood

Planted pine

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

Stand volume (mean percentage)

70

60

50

40

30

20

10

0

Natural pine

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

70

60

50

40

30

20

10

0

Oak-pine

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

70

60

50

40

30

20

10

0

Lowland hardwood

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

70

60

50

40

30

20

10

0

Upland hardwood

Stand volume (mean percentage)

LBP

Oak

SHP

SG

SLP

BC

LLP

WT

Hick

YP

OH

OS

70

60

50

40

30

20

10

0

Species codes
103

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Figure 59—Species diversity in the Pacific Northwest West subregion, forest industry, 1997.

Douglas-fir Hemlock-spruce

PSF = Pacific silver fir

WF = white fir

GF = grand fir

SS = Sitka spruce

DF = Douglas-fir

WRC = western redcedar

Stand volume (mean percentage)

Stand volume (mean percentage)

Stand volume (mean percentage) Stand volume (mean percentage)

Stand volume (mean percentage)

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

80

60

40

20

0

80

60

40

20

0

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

80 Other softwood

60

40

20

0

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

80 Other hardwood

60

40

20

0

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Red alder 80

60

40

20

0

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Species codes

WH = western hemlock

BLM = big leaf maple

RA = red alder

PM = Pacific madrone

BC = black cottonwood

OWA = Oregon white ash
104

General Technical Report PNW-GTR-613

Figure 60—Species diversity in the Pacific Northwest West subregion, nonindustrial private forest timberland, 1997.

Douglas-fir Hemlock-spruce

PSF = Pacific silver fir

WF = white fir

GF = grand fir

SS = Sitka spruce

DF = Douglas-fir

WRC = western redcedar

Stand volume (mean percentage)

Stand volume (mean percentage)

Stand volume (mean percentage) Stand volume (mean percentage)

Stand volume (mean percentage)

WH = western hemlock

BLM = big leaf maple

RA = red alder

PM = Pacific madrone

BC = black cottonwood

OWA = Oregon white ash

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Other softwood

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Other hardwood

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Red alder

PSF

WF

GF

SS

DF

WRC

WH

BLM

RA

PM

BC

OWA

Other

Species codes

80

60

40

20

0

80

60

40

20

0

80

60

40

20

0

80

60

40

20

0

80

60

40

20

0
105

Area Changes for Forest Cover Types in the United States, 1952,to 1997, With Projections to 2050

Glossary 

Afforestation—The forestation, either by human or natural forces, of nonforest 

land.

Forest cover type—A classification of forest land based on the species presently 

forming a plurality of the live-tree stocking. 

Forest cover type group—A combination of forest cover types that share closely 

associated species or site requirements and are generally combined for brevity of 

reporting (e.g., white-red-jack pine). 

Forest industry—An ownership class of private lands owned by companies or 

individuals operating wood-using plants. 

Forest Inventory and Analysis—Regional USDA Forest Service research units 

that assess forest conditions and trends on forest land and timberland. 

Forest land—Land at least 10-percent stocked by forest trees of any size, including land that formerly had such tree cover and that will be naturally or artificially 

regenerated. Forest land includes transition zones, such as areas between heavily forested and nonforested lands that are at least 10-percent stocked with forest 

trees and forest areas adjacent to urban and built-up areas. The minimum area for 

classification of forest land is 1 acre. Roadside, streamside, and shelterbelt strips of 

timber must have a crown width of at least 120 feet to qualify as forest land. Unimproved roads and trails, streams, and clearings in forest areas are classified as forest 

if less than 120 feet wide.

Forest-use land—A “major land use class” of the USDA Economic Research 

Service. This class differs from forest land in that it excludes forested land that is 

classified as “special uses” land, e.g., federal and state parks, wilderness areas, and 

wildlife refuges. 

Land area—The area of dry land and land temporarily or partly covered by water, 

such as marshes, swamps, and river flood plains; streams, sloughs, estuaries, and 

canals less than 200 feet wide; and lakes, reservoirs, and ponds less than 4.5 acres 

in area.

Miscellaneous corporate—Timberland privately owned by corporations other than 

forest industries and incorporated farms; they are part of the nonindustrial private 

forest ownership class. 

Nonindustrial private forest—An ownership class of private lands where the 

owner does not operate commercial wood-using plants.
106

General Technical Report PNW-GTR-613

Public—An ownership class, comprising land owned by federal, state, county, or 

municipal governments.

Reserved forest land—Forest land withdrawn from timber utilization through 

statute, administrative regulation, or designation.

Timberland—Forest land that is producing or is capable of producing crops of 

industrial wood and not withdrawn from timber utilization by statute or administrative regulation. (Note: Areas qualifying as timberland are capable of producing in 

excess of 20 cubic feet per acre per year of industrial wood in natural stands. Currently inaccessible and inoperable areas are included).

Urban and built-up areas—These areas consist of residential, industrial, commercial, and institutional land; construction and public administrative sites; railroad 

yards, cemeteries, airports, golf courses, sanitary landfills, sewage plants, water 

control structures, small parks, and transportation facilities within urban areas.
Pacific Northwest Research Station

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

Telephone (503) 808-2592

Publication requests (503) 808-2138

FAX (503) 808-2130

E-mail pnw_pnwpubs@fs.fed.us

Mailing address Publications Distribution

 Pacific Northwest Research Station

 P.O. Box 3890

 Portland, OR 97208-3890
UNITED STATES DEPARTMENT OF AGRICULTURE

FOREST SERVICE

PACIFIC NORTHWEST RESEARCH STATION

GENERAL TECHNICAL REPORT

PNW-GTR-613

JULY 2004