United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

General Technical 

Report

PNW-GTR-795

December 2009

DEPAR TMENT OF AGRICULT URE

A Forests on the Edge Report

Private Forests, Public Benefits:

Increased Housing Density and Other 

Pressures on Private Forest Contributions

Susan M. Stein, Ronald E. McRoberts, Lisa G. Mahal, Mary A. Carr, 

Ralph J. Alig, Sara J. Comas, David M. Theobald, and Amanda Cundiff
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, age, disability, and where applicable, 

sex, marital status, familial status, parental status, religion, sexual orientation, genetic 

information, political beliefs, reprisal, or because all or part of an individual’s income 

is derived from any public assistance program. (Not all prohibited bases apply to all 

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

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

Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write 

USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 

20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal 

opportunity provider and employer.

Authors

Susan M. Stein is a private forest-land studies coordinator, Sara J. Comas is 

a natural resource specialist, and Amanda Cundiff is an ecosystem services 

specialist, U.S. Department of Agriculture, Forest Service, Cooperative Forestry 

Staff, Mailstop 1123, 1400 Independence Avenue SW, Washington, DC 20250-

1123. Ronald E. McRoberts is a mathematical statistician, U.S. Department of 

Agriculture, Forest Service, Northern Research Station, 1992 Folwell Avenue, 

St. Paul, MN 55108. Lisa G. Mahal is a computer systems analyst, University of 

Nevada, Las Vegas, 1992 Folwell Avenue, St. Paul, MN 55108. Mary A. Carr is 

a technical publications editor, U.S. Department of Agriculture, Forest Service, 

Ecosystem Management Coordination Publishing Arts, 1835 Black Lake 

Boulevard SW, Olympia, WA 98512. Ralph J. Alig is a research forester, U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station, 

3200 SW Jefferson Way, Corvallis, OR 97331. David M. Theobald is a research 

scientist, Colorado State University, Natural Resource Ecology Laboratory, 

Fort Collins, CO 80523-1499.

Cover photos: (top) housing development, ©Harrison Shull, Aurora Photos; 

(bottom) red trillium ©Hamiza Bakirci, iStockPhoto.com; red squirrel, Michael 

Mengak, University of Georgia, Bugwood.org; Oregon hikers, Tom Iraci; logs, 

U.S. Forest Service.

Back cover photos: Key deer (Odocoileus virginianus clavium), U.S. Fish and 

Wildlife Service; chanterelle mushrooms, U.S. Forest Service.
Abstract

Stein, Susan M.; McRoberts, Ronald E.; Mahal, Lisa G.; Carr, Mary A.; Alig, 

Ralph J.; Comas, Sara J.; Theobald, David M.; Cundiff, Amanda. 2009. 

Private forests, public benefits: increased housing density and other pressures 

on private forest contributions. Gen. Tech. Rep. PNW-GTR-795. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 74 p.

Over half (56 percent) of America’s forests are privately owned and managed and 

provide a vast array of public goods and services, such as clean water, timber, 

wildlife habitat, and recreational opportunities. These important public benefits are 

being affected by increased housing density in urban as well as rural areas across 

the country. The Forests on the Edge project, sponsored by the U.S. Department of 

Agriculture, Forest Service, seeks to improve our understanding of where across 

the country housing density increases, as well as other threats, might affect these 

critical goods and services. For this study, we map and rank watersheds across 

the conterminous United States to analyze the relative contributions of private 

forest land to water quality, timber volume, at-risk species habitat, and interior 

forest. In addition, we rank watersheds according to the pressures on private 

forest contributions from increased housing density, wildfire, insect pests and 

diseases, and air pollution. Results indicate that private forest land contributions 

to forest cover, clean water, and timber volume are greatest in the East, but are 

also important in many Western watersheds. Private forests making substantial 

contributions to interior forest and at-risk species are more uniformly distributed 

across the country. Development pressures on these contributions are concentrated 

in the Eastern United States but are also found in the north-central region, parts 

of the West and Southwest, and the Pacific Northwest; nationwide, more than 57 

million acres of rural forest land are projected to experience a substantial increase 

in housing density from 2000 to 2030. Private forests in both the Eastern and 

Western United States are under pressure from insect pests and diseases. The bulk 

of private forests most susceptible to wildfire are located in the West and parts 

of the Southeast. Lastly, ozone pollution affecting private forests is localized in 

California and several areas of the East.

Keywords: Private forest, housing density, ecosystem services, water quality, 

at-risk species, interior forest, wildfire, insect pests, diseases, ozone.
Contents

1 Introduction

3 America’s Private Forests

4 Private Forest Owners

6 Forest Ownership Changes

8 Assessing Housing Density Increases and Other Pressures 

 on Private Forest Contributions

12 Private Forest Benefits and Housing Density Increases

16 Water Quality

20 Timber Volume

24 Habitats for At-Risk Species

28 Interior Forests

33 Additional Pressures

34 Insect Pests and Diseases

40 Wildfire

46 Air Pollution

51 Summary and Conclusions

53 Acknowledgments

54 Metric Equivalents

54 References

66 Appendix

66 Methodology

67 Private Forest Contributions

70 Threats to Private Forest Lands

73 Sensitivity Analyses
1

Increased Housing Density and Other Pressures on Private Forest Contributions

AMERICA’S FOREST LANDS provide a wealth of goods and services to 

the public—from helping ensure clean water and abundant forest products, to 

providing wildlife habitat, open spaces, and opportunities for outdoor recreation 

and education. Private forest contributions to these goods and services can be 

affected by increased housing density. Additional threats, such as fire and forest 

pests, can further exacerbate the effects of increased housing density. Although 

the focus of this report is on increased housing density, housing density increases 

are typically associated with additional development, including increases in related 

infrastructure, such as roads and other transportation networks, which also have 

environmental impacts. In fact, in some urban areas, a 10-percent increase in 

population growth can, in certain periods, lead to a 40- to 60-percent increase 

in urban land cover (Daniels 1999).

This report is one of several produced by the U.S. Department of Agriculture, 

Forest Service as part of the Forests on the Edge project. It displays and describes 

information at a national level that can improve understanding of forest land development issues and can help answer such questions as:

• Where, nationwide, do private forests make substantial contributions to 

clean water, timber volume, habitat for at-risk plant and animal species,

 or interior forest? 

• Where are these contributions likely to change because of increased housing 

density in rural private forests? Our use of term “increased housing density” 

refers to a very specific change in housing density such that land shifts out of 

a rural housing density category to a higher density category (see page 9).

Introduction

Annette Wiechmann, 

©iStockphoto.com

America’s private 

forests provide many 

public benefits, 

including clean water.
2

PRIVATE FORESTS, PUBLIC BENEFITS

• Where is change from increased housing density likely to be exacerbated 

by other factors such as insect pests and diseases, wildfire, or air pollution?

• Where are private forest lands that are making the most important 

contributions also facing the greatest pressures?

We analyzed selected contributions and pressures 

for which nationally consistent data were available. The 

pressures analyzed represent only a sampling of the 

numerous factors that affect private forests across the 

country. Similar to other Forests on the Edge reports 

and other national assessments, our findings may not 

completely capture changes at all scales or in specific 

watersheds.

The data are analyzed by watershed—an area of 

land that drains into a river, stream, or other body of 

water—to emphasize the vital connection between 

private forests and clean water. Summarizing detailed 

data by a larger entity such as a watershed also is a 

useful way to organize and communicate our results.

The first section of this report focuses on identifying areas where contributions provided by private 

forests could be affected by increased housing density. 

SPONSORED BY the State and Private Forestry, 

Cooperative Forestry staff of the USDA Forest 

Service, in cooperation with Forest Service 

Research and Development, the Forests on the 

Edge project uses data prepared and analyzed by 

scientists across the country to increase understanding of the many public benefits derived from 

private forests and of the pressures that might 

affect these benefits. 

The Forests on the Edge project is one of 

several efforts to assess the status, condition, 

and trends of forests across the United States. 

The number, scope, and complexity of these 

efforts reflect the critical importance of conserving and maintaining global forest resources. Major 

efforts include work by the Forest Service Eastern 

and Western Wildland Threat Centers (USDA FS, 

n.d.); Resource Planning Act assessments (USDA 

Forest Service 2007b); national work in climate 

change and policy analysis; and international 

guidelines for sustainable forest management such 

as the United Nations Framework Convention on 

Climate Change (http://unfccc.int/2860.php), the 

Montréal Process (criteria and indicators) (http://

www.rinya.maff.go.jp/mpci/), and the Ministerial 

Conference on the Protection of Forests in Europe 

(MCPFE) (http://www.mcpfe.org/) . 

About the Forests on the Edge Project © Jerry and Marcy Monkman/EcoPhotography.com
3

Increased Housing Density and Other Pressures on Private Forest Contributions

Following this, we identify areas where the detrimental effects of increased 

housing density may be compounded by or may intensify the effects of additional 

pressures from insects and diseases, wildfire, and ozone pollution. An appendix 

provides details on methods used in each assessment.

Additional maps can be found on the Forests on the Edge Web site (http://www.

fs.fed.us/openspace/fote), including completed maps and digital data that can be 

used to make individualized maps showing various combinations of layers.

America’s Private Forests

About 56 percent, more than 420 million acres, of America’s forests are privately 

owned (Smith et al. 2004) (fig. 1). About three-quarters of these private forests are 

located in the Eastern United States, but ecologically valuable private forest lands 

are also found in the West, where some of the fastest population growth in the 

country is taking place.

For the purpose of this study, we define forest as land with at least 25 percent 

tree crown cover from trees that are greater than 20 feet tall. We chose this definition because it is the one used by the U.S. Geological Survey (USGS) in creating 

the forest cover data used for this report (see “About the National Land Cover Data” 

on page 5).

Private forest is forest land owned by individuals, families, corporations, 

organizations, tribes, or the forest industry. Public lands—that is, lands owned by 

federal, state, or local governments—were not included in this study because they 

are not typically available for development.

Chris Evans, River to River CWMA, Bugwood.org

Fifty-six percent 

of U.S. forests are 

privately owned.
4

PRIVATE FORESTS, PUBLIC BENEFITS

Private forests play a key role in protecting water quality, furnishing diverse 

habitats for fish and wildlife, providing the raw materials for timber products and 

other forest goods or services, and sustaining valuable ecological functions across 

the landscape such as flood and climate regulation (see sidebar on page 6). These 

benefits are often characterized as ecosystem goods or services and are subject to 

alteration because of housing development and environmental pressures.

Private Forest Owners

America’s private forests are owned and managed by approximately 11 million 

private landowners, most of whom (close to 8 million landowners) have relatively 

small holdings of fewer than 50 acres each (Butler 2008). A quarter of private forest 

land acres are owned by corporations, other private organizations, and individuals 

who have large holdings of 5,000 acres or more (fig. 2).

Figure 1—Location of private and public forest, nonforest, and urban areas. About three-quarters of America’s private forests are in 

the East.
5

Increased Housing Density and Other Pressures on Private Forest Contributions

Private landowners are key stewards 

of our forests, but costs for conserving 

and maintaining their forests can be high. 

Private forest landowners in many parts 

of the country are under pressure to sell 

their land for development or other uses 

(Alig 2007). The Forest Service and other 

agencies and organizations are working to 

find market-based approaches that provide 

landowners with economic incentives to 

retain and conserve these lands. More 

information on ecosystem services 

can be found at http://www.fs.fed.us/

ecosystemservices. 

Figure 2—Percentage of private forest acres by parcel size. 

Source: Butler (2008).

About the National Land Cover Data

THE 2001 NATIONAL Land Cover Data (NLCD) 

database was recently released and forms the 

basis for our forest cover layer (Homer et al. 

2007). The NLCD database provides 21 land 

cover classes from Landsat satellite imagery 

and ancillary data for the conterminous 48 states 

(also referred to as the “Lower 48”). The detailed 

data are widely used for an array of applications 

including national environmental reporting, climate 

change investigations, clean water studies, and 

biodiversity and conservation assessments. This 

Forests on the Edge report uses three categories of 

forest vegetation as defined by the NLCD:

• Deciduous forest—Areas dominated 

by trees where 75 percent or more of 

the trees shed foliage in response to 

seasonal change.

• Evergreen forest—Areas dominated by 

trees where 75 percent or more of the 

trees retain their leaves all year. 

• Mixed forest—Areas dominated by trees 

where neither deciduous nor evergreen 

species represent more than 75 percent 

of the cover present.

—Sources: Homer et al. 2007; 

 USGS, n.d.; US EPA, n.d. 

© Jerry and Marcy Monkman
6

PRIVATE FORESTS, PUBLIC BENEFITS

Forest Ownership Changes

Millions of acres of large tracts of private forest once owned by traditional forest 

industry companies have been sold since the mid-1990s, owing in part to changes in 

tax codes, shifts in forest land market values, and business decisions (Butler 2008). 

The South has seen the most substantial changes—of the 23 million acres of industrial timberland sold in the United States from 2000 through 2004, approximately 

18 million were in the South—but such transactions have also occurred in major 

timber-growing regions elsewhere in the country (Clutter et al. 2005). In northern 

Maine, for example, industrial landowners have subdivided and sold most of their 

timberland properties; one timber industry firm alone transferred 2.3 million acres 

to 15 owners during and since the 1990s (LeVert et al. 2008). Such a change in 

ownership patterns—where larger forested tracts are divided into multiple parcels 

owned by several owners—is known as parcelization.

Forests and Climate Change

FORESTS SEQUESTER (store) carbon and thereby 

help to reduce the amount of carbon dioxide (CO2) in 

the atmosphere. Carbon dioxide is a greenhouse gas 

that enters the atmosphere from the burning of fossil 

fuels, solid waste, trees, and wood products, and 

also as a result of other chemical reactions. The U.S. 

Environmental Protection Agency (US EPA 2009b) 

defines a greenhouse gas as “any gas that absorbs 

infrared radiation in the atmosphere,” such as CO2, 

water vapor, methane (CH4), and nitrous oxide 

(N2O). Greenhouse gases lead to the greenhouse 

effect, in which heat is trapped and accumulated 

in the atmosphere near the Earth’s surface. This 

in turn leads to global warming, which EPA defines 

as “an average increase in the temperature of the 

atmosphere near the Earth’s surface and in the 

troposphere, which can contribute to changes 

in global climate patterns.” United States forests 

currently sequester about 10 percent of U.S. carbon 

emissions (Woodbury et al. 2007). Therefore, the 

maintenance and proper management of private 

forests are critical to mitigating greenhouse gas 

emissions and global climate change.

David Cappaert, Michigan State University, Bugwood.org
7

Increased Housing Density and Other Pressures on Private Forest Contributions

The impact of industry sales on forest parcelization is being studied but may 

not be completely understood for decades. Much of this land has been sold to 

institutional investors whose objective is to turn a profit in a shorter period than 

that pursued by traditional industrial owners. Although many timberlands sold do 

continue to be managed for timber production, changing ownership has led to and 

will likely continue to lead to the sale of some commercial timberland for real estate 

purposes (Clutter et al. 2005, Mendell et al. 2005). In Minnesota, for example, 

timber and mining industry landowners are selling thousands of acres to financial 

investors who value both large and small forest parcels in part for their potential to 

be subdivided and sold for real estate development (Johnson and Stone 2008).

Accelerated changes in the ownership of smaller tracts that are not owned by 

forest industry or institutional investors are also likely to occur in coming decades 

as an aging generation of owners disposes of or transfers landholdings. More than 

60 percent of current private forest landowners are age 55 or older and own a total 

of 170 million acres of private forest. More than 15 percent of private forest land 

Gordon Bradley, University of Washington

Turnover in land 

ownership can lead to 

forest parcelization.
8

PRIVATE FORESTS, PUBLIC BENEFITS

owners are age 75 or older and own about 52 million acres of forest (Butler 2008). 

Although many of these older generations own land for reasons largely unrelated to 

finances, these owners or their heirs may be compelled to subdivide and sell their 

property if confronted by daunting economic and social challenges (Butler 2008). 

Smaller, more fragmented (or disconnected) parcels can lead to a host 

of changes in water quality and aquatic species diversity, timber volume and 

management, native wildlife populations, forest structure and function, wildfire 

risk, and scenic quality and recreational opportunities (Sampson and Decoster 

2000, Smail and Lewis 2009, Stein et al. 2005). The size of forest holdings is 

also highly correlated with behaviors and attitudes of forest owners, such as their 

management objectives, plans to transfer the property to others, and willingness 

to prepare forest management plans (Butler 2008).

Assessing Housing Density Increases and Other 

Pressures on Private Forest Contributions

To assess the potential for increased housing density and other factors that 

affect private forests, nationally consistent data layers were constructed and 

then summarized at the spatial scale of 4th-level watersheds (see “What Is a 

Watershed?” below) (Steeves and Nebert 1994). Only watersheds with at least 

10 percent forest cover and containing at least 10,000 acres of private forest 

were considered for the study (fig. 3). 

What Is a Watershed? 

A WATERSHED generally is an area 

of land that catches rainfall and other 

precipitation and funnels it into a 

network of marshes, streams, rivers, 

lakes, soils, or groundwater. Watersheds 

also are specific hydrological units 

defined by the U.S. Geological Survey. 

The 2,108 fourth-level (also known as 

8-digit) watersheds in the conterminous 

United States average approximately 

1 million acres in size but range 

from approximately 22,000 acres to 

approximately 13 million acres. 

Lynn Betts, USDA Natural Resources Conservation Service

Susan Stein
9

Increased Housing Density and Other Pressures on Private Forest Contributions

As in previous Forests on the Edge studies, increased housing density here refers 

to a projected increase in housing density between 2000 and 2030—that is, an 

increased number of housing units per unit area on rural lands such that the housing 

density category would shift to a higher-level category (Stein et al. 2005, 2007; 

Theobald 2005). Rural I lands are defined as those with fewer than 16 housing units 

per square mile; rural II refers to lands with 16 to 64 housing units per square mile; 

and exurban/urban lands support more than 64 housing units per square mile. 

Housing density projections are based on several factors including past and current 

statistics on housing density and population, past growth patterns, road densities, and 

locations of urban areas (Theobald 2005). Our housing density projections excluded 

Figure 3—Watersheds by percentage of private forest cover. This map displays watersheds according to the percentage of each 

watershed containing private forest land. The highest ranked watersheds are found in the East and are concentrated in Maine, 

Vermont, West Virginia, Arkansas, and Alabama. Most of West Virginia’s watersheds are also ranked in the 90th percentile.
10

PRIVATE FORESTS, PUBLIC BENEFITS

Bill Hull bought his first woodlot—12 acres of hardwoods—when he was 15 years old. Over time he 

created the largest and most progressive hardwood 

sawmill in southern New England and founded two 

family-owned forest products and resources companies. Hull aims to conserve working forest lands and 

to help preserve New England-style communities. 

To that end he placed the 12,000 acres of company 

lands in two states under conservation easements, 

thus protecting them from development and increasing the funds he has available to conserve more 

land. He also created a limited partnership to assure 

that the companies he established will continue, 

even if his children choose not to continue in the 

family business. Management of the Hull forests 

meets the Forest Stewardship Council’s (FSC) 

management standard as certified by the FSCaccredited auditing firm, SmartWood.

“You Can’t Make a Living Growing Trees in New England Anymore.”

Stating that “you can’t make a living growing 

trees in New England anymore,” Mr. Hull has found 

other ways to supplement his income and hold onto 

the land—such as offering recreational leases to 

private groups who use the properties for activities 

ranging from hunting and fishing to hiking, stargazing, and pure enjoyment of nature. 

Primary threats facing the Hull forest properties 

include development and fragmentation related 

to increasing human population growth in the 

region. Countless brochures arrive from real estate 

companies as far away as California urging Mr. Hull 

to “cash in” on his land. Trespass and unauthorized 

all-terrain vehicle (ATV) use are related problems, 

resulting in substantial road damage and increased 

maintenance costs.

This northern hardwood, hemlock, and oak forest owned by Hull Forest Products has extensive 

frontage on the federally designated “wild and scenic” Westfield River in Huntington, Massachusetts. Owner Bill Hull has used a variety of options to protect and manage the land as working forest.Bill Hull

Faces of Private Forest Owners Bill Hull
11

Increased Housing Density and Other Pressures on Private Forest Contributions

An Unclear Future

Jim LeTourneux and his family derive a living and a 

lifestyle from their forest.

Sandy LeTourneaux

More than 40 years ago, Jim Letourneux bought 

the Oregon land his parents had acquired when he 

was a child, becoming owner of 400 acres that he 

and his wife Sandy now manage as the Tripletree 

LLC timber farm. LeTourneux family members 

raise trees that will become saw logs and poles, 

and they also enjoy the property for recreation. 

They take pleasure in the long-term goals and 

aspirations that go along with growing trees that 

can take decades to reach their full potential.

Some of their neighbors have begun to file 

claims to subdivide their land into small lots, where 

homes will be built on what has been private forest 

land for generations. The impending development 

and wildfire danger—which Mr. LeTourneux 

believes go hand-in-hand—are the main pressures 

on the LeTourneux property today, along with 

invasive species. 

Although their sons are not interested in 

owning and running a farm, Jim and Sandy 

LeTourneux don’t want their land partitioned—a 

goal that may be difficult to achieve in the face of 

the development trend around them. 

Faces of Private Forest Owners

lands recorded in a national database as being protected from development by conservation easements 

(CBI 2007, DellaSalla et al. 2001, Theobald 2007).

For each data layer analyzed (for example, water 

quality, at-risk-species, increased housing density, or 

fire) a percentile ranking was assigned to each watershed. For example, watersheds in which private forests 

provide habitat for the greatest number of at-risk 

species fall in the highest (90th percentile) category, 

whereas watersheds containing the fewest at-risk 

species fall in the low (0 to 50th percentile) category.

To identify areas where contributions might be 

most likely to decline as a result of future increases in 

housing density, we re-ranked each watershed according to the average of the percentile categories of the 

two layers. For example, if a watershed was in the 96th

percentile for at-risk species and the 82nd percentile 

for housing density increase, it would be placed in the 

89th percentile for at-risk species and housing density 

increase. 

White watersheds on each map represent areas 

that did not meet this study’s screening criteria (10 

percent forested with at least 10,000 acres of private 

forest). This does not mean that private forest holdings 

in these watersheds are not important; the white areas 

may actually contain small acreages of private forests 

of high local significance. Several maps contain white 

watersheds with cross-hatches. These are watersheds 

for which there were no data for that layer.

For a brief description of data constraints, see 

“Data and Analysis Considerations” on page 15. A 

description of how each data layer was constructed is 

provided in the appendix and in Stein et al. (in press). 

Data used to create these maps represent more upto-date information than was available for previous 

Forests on the Edge papers and studies. 

See the appendix for a detailed description of the 

methods used to make the maps in this section.