United States 

Department of 

Agriculture

Forest Service

Pacific Southwest 

Research Station

General Technical 

Report

PSW-GTR-206

November 2007

Community

Benefits, Costs, and Strategic Planting

Temperate Interior West

Tree Guide

Kelaine E. Vargas, E. Gregory McPherson, James R. Simpson, Paula J. Peper, 

Shelley L. Gardner, and Qingfu Xiao
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 

Kelaine E. Vargas is a landscape architect, E. Gregory McPherson is a research 

forester, James R. Simpson is a forest meteorologist, Paula J. Peper is an ecologist, and Shelley L. Gardner was a forester at the U.S. Department of Agriculture, 

Forest Service, Pacific Southwest Research Station, Center for Urban Forest 

Research, Department of Plant Sciences, MS-6, University of California Davis, One 

Shields Ave., Davis, CA 95616; Qingfu Xiao is a research hydrologist, Department 

of Land, Air, and Water Resources, University of California, Davis, One Shields 

Ave., Davis, CA 95616. Gardner is currently with the Office of Communications, 

1400 Independence Ave., SW, Washington, DC 20250. 
Temperate Interior West 

Community Tree Guide: 

Benefits, Costs, and Strategic Planting

Kelaine E. Vargas, E. Gregory McPherson, James R. Simpson, 

Paula J. Peper, Shelley L. Gardner, and Qingfu Xiao

U.S. Department of Agriculture, Forest Service

Pacific Southwest Research Station

Albany, CA

General Technical Report 

PSW-GTR-206

November 2007

This work was sponsored by the U.S. Department of Agriculture, Forest Service, 

State and Private Forestry, Urban and Community Forestry Program; the State of 

Nevada, Department of Conservation and Natural Resources, Division of Forestry; 

the State of Idaho, Department of Lands, Community Forestry; and the City of 

Boise, Department of Parks and Recreation.
ii

GENERAL TECHNICAL REPORT PSW-GTR-206 

Abstract

Vargas, Kelaine E.; McPherson, E. Gregory; Simpson, James R.; Peper, 

Paula J.; Gardner, Shelley L.; Xiao, Qingfu. 2007. Temperate Interior West 

community tree guide: benefits, costs, and strategic planting. Gen. Tech. Rep. 

PSW-GTR-206. Albany, CA: U.S. Department of Agriculture, Forest Service, 

Pacific Southwest Research Station. 108 p.

Even as they increase the beauty of our surroundings, trees provide us with a great 

many ecosystem services, including air quality improvement, energy conservation, 

stormwater interception, and atmospheric carbon dioxide reduction. These benefits 

must be weighed against the costs of maintaining trees, including planting, pruning, 

irrigation, administration, pest control, liability, cleanup, and removal. We present benefits and costs for representative small, medium, and large deciduous trees 

and coniferous trees in the Temperate Interior West region derived from models 

based on indepth research carried out in Boise, Idaho. Average annual net benefits 

increase with tree size and differ based on location: $12 (public) to $24 (yard) for a 

small tree, $30 (public) to $45 (yard) for a medium tree, $49 (public) to $63 (yard) 

for a large tree, $22 (public) to $25 (yard) for a conifer. Two hypothetical examples 

of planting projects are described to illustrate how the data in this guide can be 

adapted to local uses, and guidelines for maximizing benefits and reducing costs 

are given.

Keywords: Ecosystem services, Temperate Interior West, urban forestry, 

benefit-cost analysis.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

iii

Executive Summary

This report quantifies benefits and costs for representative small, medium, and large 

deciduous trees and conifers in the Temperate Interior West region: the species chosen as representative are the crabapple, Norway maple, white ash, and blue spruce 

(see “Common and Scientific Names” section). The analysis describes “yard trees” 

(those planted in residential sites) and “public trees” (those planted on streets or in 

parks). Benefits are calculated based on tree growth curves and numerical models 

that consider regional climate, building characteristics, air pollutant concentrations, 

and prices. Tree care costs and mortality rates are based on results from a survey of 

municipal and commercial arborists. We assume a 43-percent survival rate over a 

40-year timeframe.

The measurements used in modeling environmental and other benefits of trees 

are based on indepth research carried out in Boise, Idaho. Given the Temperate 

Interior West region’s diverse geographical area, this approach provides general 

approximations based on some necessary assumptions that serve as a starting point 

for more specific local calculations. It is a general accounting that can be easily 

adapted and adjusted for local planting projects. Two examples are provided that 

illustrate how to adjust benefits and costs to reflect different aspects of local urban 

forest improvement projects.

Large trees provide the most benefits. Average annual benefits increase with 

mature tree size and differ based on tree location. The lowest values are for yard 

trees on the southern side of houses, and the highest values are for yard trees on the 

western side of houses. Values for public trees are intermediate. Average annual 

benefits range as follows:

• $25 to $32 for a small tree

• $39 to $55 for a medium tree

• $58 to $74 for a large tree

• $32 to $33 for a conifer

Benefits associated with reduced energy use and increased aesthetic and other 

benefits reflected in higher property values account for the largest proportion of 

total benefits in this region. Reduced levels of stormwater runoff, air pollutants, and 

carbon dioxide (CO2) in the air are the next most important benefits. 

Energy conservation benefits differ with tree location as well as size. Trees 

located opposite west-facing walls provide the greatest net heating and cooling 

energy savings. Reducing heating and cooling energy needs reduces CO2 emissions and thereby reduces atmospheric CO2. Similarly, energy savings that reduce 

Benefits and costs 

quantified

Average annual 

benefits
iv

GENERAL TECHNICAL REPORT PSW-GTR-206 

demand from power plants account for important reductions in gases that produce 

ozone, a major component of smog, and other air pollutants. 

The benefits of trees are offset by the costs of caring for them. Based on our 

surveys of municipal and residential arborists, the average annual cost for tree 

care ranges from $7 to $19 per tree. (Values below are for yard and public trees, 

respectively.)

• $8 and $16 for a small tree

• $10 and $18 for a medium tree

• $11 and $19 for a large tree

• $7 and $12 for a conifer

Planting costs, annualized over 40 years, are a significant expense ($4 per tree 

per year). Pruning ($1 to $7 per tree per year) and removal and disposal annualized 

over 40 years ($2 to $3 per tree per year) are the next greatest costs. Public trees 

also incur administrative expense ($2 to $3 per tree per year). During the establishment period, costs for labor-intensive hand watering were estimated to be $2 per 

year for 5 years. 

Average annual net benefits (benefits minus costs) per tree for a 40-year period 

differ with tree location and tree size and range from a low of $12 to a high of $62 

per tree.

• $12 for a small public tree to $24 for a small yard tree on the west side of a 

house

• $29 for a medium yard tree on the south side of a house to $45 for a medium 

yard tree on the west side of a house

• $47 for a large yard tree on the south side of a house to $63 for a large yard tree 

on the west side of a house

• $22 for a public conifer to $25 for a yard conifer in a windbreak

Environmental benefits alone, including energy savings, stormwater runoff 

reduction, improved air quality, and reduced atmospheric CO2, can be more than 

five times tree care costs.

Net benefits for a yard tree opposite a west wall and a public tree are substantial 

when summed over the 40-year period (values below are for yard trees opposite a 

west wall and public trees, respectively):

• $953 and $479 for a small tree

• $1,784 and $1,184 for a medium tree

Costs

Average annual net 

benefits

Net benefits summed 

over 40 years
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

• $2,497 and $1,931 for a large tree

• $984 and $840 for a conifer

Yard trees produce higher net benefits than public trees, primarily because of 

lower maintenance costs.

To demonstrate ways that communities can adapt the information in this report 

to their needs, examples of two fictional cities interested in improving their urban 

forest have been created. The benefits and costs of different planting projects are 

determined. In the hypothetical city of Chinook Valley, net benefits and benefit-cost 

ratios (BCRs; total benefits divided by costs) are calculated for a planting of 1,000 

trees (2-in caliper) assuming a cost of $200 per tree, 43 percent mortality rate, and 

40-year analysis. Total benefits are $2.16 million, total costs are about $750,000, 

and net benefits are $1.41 million ($35.73 per tree per year). The BCR is 2.93:1, 

indicating that $2.93 is returned for every $1 invested. The net benefits and BCRs 

(in parentheses) by mature tree size are:

• $16,396 (1.49:1) for 50 crabapple trees

• $149,988 (2.33:1) for 150 Norway maples

• $1,185,384 (3.19:1) for 700 white ash

• $73,801 (2.48:1) for 100 blue spruce

Increased property values reflecting aesthetic and other benefits of trees 

account for about half (46 percent) of the estimated benefits, and reduced energy 

costs for another 40 percent. Reduced stormwater runoff (10 percent), air quality 

improvement (2 percent), and atmospheric CO2 reduction (2 percent) make up the 

remaining benefits. 

In the fictional city of Solanum, long-term planting and tree care costs and 

benefits were compared to determine if a proposed policy that might favor planting 

small trees would be cost-effective compared to the current policy of planting large 

trees where space permits. Over a 40-year period, the net benefits are:

• $385 for a small tree

• $1,070 for a medium tree

• $1,791 for a large tree

Based on this analysis, the city of Solanum decided to strengthen its tree 

ordinance, requiring developers to create tree shade plans that show how they will 

achieve 50-percent shade over streets, sidewalks, and parking lots within 15 years 

of development.
vi

GENERAL TECHNICAL REPORT PSW-GTR-206 

Contents

1 Chapter 1. Introduction

1 The Temperate Interior West Region

5 Chapter 2. Benefits and Costs of Urban and Community 

 Forests

5 Benefits

5 Saving Energy

8 Reducing Atmospheric Carbon Dioxide

10 Improving Air Quality

13 Reducing Stormwater Runoff and Improving Hydrology

16 Aesthetics and Other Benefits

20 Costs

21 Planting and Maintaining Trees

22 Conflicts With Urban Infrastructure

25 Chapter 3. Benefits and Costs of Community Forests in 

 Temperate Interior West Communities

25 Overview of Procedures

25 Approach

29 Reporting Results

29 Findings of This Study

29 Average Annual Net Benefits

30 Average Annual Costs

32 Average Annual Benefits

37 Chapter 4. Estimating Benefits and Costs for Tree Planting 

 Projects in Your Community

37 Applying Benefit-Cost Data

37 Chinook Valley Example

42 City of Solanum Example

45 Increasing Program Cost-Effectiveness

45 Increasing Benefits

46 Reducing Program Costs
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

vii

49 Chapter 5. General Guidelines for Selecting and Placing Trees

49 Guidelines for Energy Savings

49 Maximizing Energy Savings from Shading

51 Planting Windbreaks for Heating Savings

52 Selecting Trees to Maximize Benefits

53 Guidelines for Reducing Carbon Dioxide

54 Guidelines for Reducing Stormwater Runoff

55 Guidelines for Improving Air Quality Benefits

56 Guidelines for Avoiding Conflicts With Infrastructure

58 Guidelines for Maximizing Long-Term Benefits

61 Glossary of Terms

66 Common and Scientific Names

67 Metric Equivalents

67 Acknowledgments

68 References

81 Appendix 1: Additional Resources

83 Appendix 2: Benefit–Cost Information Tables

93 Appendix 3: Procedures for Estimating Benefits and Costs

93 Approach

93 Pricing Benefits and Costs

93 Growth Modeling

95 Reporting Results

96 Benefit and Cost Valuation

96 Calculating Benefits

96 Calculating Energy Benefits

98 Atmospheric Carbon Dioxide Reduction

101 Stormwater Benefits

102 Aesthetic and Other Benefits

104 Calculating Costs

104 Planting
viii

GENERAL TECHNICAL REPORT PSW-GTR-206 

104 Pruning

105 Tree and Stump Removal

105 Pest and Disease Control

105 Irrigation Costs

105 Other Costs for Public and Yard Trees

106 Calculating Net Benefits

106 Benefits Accrue at Different Scales

108 Limitations of This Study
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

Chapter 1. Introduction

The Temperate Interior West Region

From Boise, Idaho, to Reno, Nevada, to the cities of southeastern Washington and 

some parts of coastal Oregon, and portions of southern California, the Temperate 

Interior West region (fig. 1) contains a diverse assemblage of municipalities. The 

climate1 of this region, which corresponds to Sunset climate zone 3 (Brenzel 2001), 

is characterized by hot, dry summers and winters that are cold but milder than the 

surrounding areas. Average summer high temperatures range from the low 90s in 

the interior areas to the high 60s along the Oregon coast; winter low temperatures 

in the interior regions are usually below freezing and may drop far below zero, 

whereas winters along the coast are much milder, with low temperatures averaging 

in the mid to upper 30s. Precipitation rates range from approximately 30 in along 

the Oregon coast to 8 in Reno, with the majority falling in the winter.

1 Words in bold are defined in the glossary.

Figure 1—The Temperate Interior West region covers the milder areas of the snowy West, including eastern areas of the Columbia River, portions of Nevada east of the Sierra Nevada, portions of 

southern California, and the coast ranges of Oregon and Washington.

Scope of the 

Temperate Interior 

West region
GENERAL TECHNICAL REPORT PSW-GTR-206 

As the communities of the Temperate Interior West continue to grow and 

change during the coming decades, growing and sustaining healthy community 

forests is integral to the quality of life that residents experience. The urban forest 

is a distinctive feature of the landscape that protects us from the elements, cleans 

the water we drink and the air we breathe, and forms a connection to earlier generations who planted and tended the trees. 

The role of urban forests in enhancing the environment, increasing community 

attractiveness and livability, and fostering civic pride takes on greater significance 

as communities strive to balance economic growth with environmental quality and 

social well-being. The simple act of planting trees provides opportunities to connect residents with nature and with each other (fig. 2). Neighborhood tree plantings 

and stewardship projects stimulate investment by local citizens, businesses, and 

governments for the betterment of their communities. Community forests bring 

opportunity for economic renewal, combating development woes, and increasing 

the quality of life for community residents.

Temperate Interior West communities can promote energy efficiency through 

tree planting and stewardship programs that strategically locate trees to save energy 

and minimize conflicts with urban infrastructure. The same trees can provide additional benefits by reducing stormwater runoff; improving local air, soil, and water 

quality; reducing atmospheric carbon dioxide (CO2); providing wildlife habitat; 

increasing property values; slowing traffic; enhancing community attractiveness 

and investment; and promoting human well-being.

Figure 2—Tree planting and stewardship programs provide opportunities for local residents to work 

together to build better communities.

Temperate Interior 

West communities 

can derive many 

benefits from urban 

forests
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

Although trees can provide many benefits to residents of the Temperate Interior 

West, trees are not always an inherent part of these ecosystems. Therefore few 

native species may be available for planting, and those that are may be inappropriate for urban settings. There may be concern over the introduction of nonnative 

trees that they may prove to be invasive, particularly in riparian areas, provide 

habitat for nonnative fauna, and encroach on nearby native habitats. These concerns 

are valid, considering for example, the invasion of the tree of heaven (see “Common and Scientific Names” section) along the Sacramento and American Rivers in 

California (Hunter 2000) and along the Rio Grande (Tellman 1997) and of Russian 

olive throughout the Western United States (Brock 1998). Careful species selection 

in collaboration with your local extension agent or city forester can allay these 

concerns while allowing local communities to reap the many benefits of trees in 

urban areas.

This guide builds upon studies by the USDA Forest Service in Chicago and 

Sacramento (McPherson et al. 1994, 1997), and other regional tree guides from 

the Center for Urban Forest Research (McPherson et al. 1999b, 2000, 2003, 2004, 

2006a, 2006b, 2006c, in press; Vargas et al., in press) to extend knowledge of urban 

forest benefits in the Temperate Interior West. The guide:

• Quantifies benefits of trees on a per-tree basis rather than on a canopy 

cover basis (it should not be used to estimate benefits for trees growing in 

forest stands).

• Describes management costs and benefits.

• Details how tree planting programs can improve environmental quality, conserve energy, and add value to communities.

• Explains where to place residential yard and public trees to maximize their benefits and cost-effectiveness.

• Describes ways to minimize conflicts between trees and power lines, sidewalks, and buildings.

• Illustrates how to use this information to estimate benefits and costs for local 

tree planting projects.

These guidelines are specific to the Temperate Interior West, and are based on 

data and calculations from open-growing urban trees in this region. 

Street, park, and shade trees are components of all Temperate Interior West 

communities, and they affect every resident. Their benefits are myriad. However, 

with municipal tree programs dependent on taxpayer-supported general funds, 

communities are forced to ask whether trees are worth the price to plant and care 

for over the long term, thus requiring urban forestry programs to demonstrate 

Scope defined

Audience and 

objectives
GENERAL TECHNICAL REPORT PSW-GTR-206 

their cost-effectiveness (McPherson 1995). If tree plantings are proven to benefit 

communities, then financial commitment to tree programs will be justified. 

Therefore, the objective of this tree guide is to identify and describe the benefits 

and costs of planting trees in Temperate Interior West communities—providing a 

tool for municipal tree managers, arborists, and tree enthusiasts to increase public 

awareness and support for trees (Dwyer and Miller 1999).
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting



Chapter 2. Benefits and Costs of Urban and Community 

Forests

This chapter describes benefits and costs of public and privately managed trees 

and presents the functional benefits and associated economic value of community 

forests. Expenditures related to tree care and management are assessed—a necessary process for creating cost-effective programs (Dwyer et al. 1992, Hudson 1983).

Benefits

Saving Energy

Energy is an essential ingredient for quality of life and for economic growth. 

Conserving energy by greening our cities is often more cost-effective than building new power plants. For example, while California was experiencing energy 

shortages in 2001, its 177 million city trees were providing shade and conserving 

energy. Annual savings to utilities were an estimated $500 million in wholesale 

electricity and generation purchases (McPherson and Simpson 2003). Planting 50 

million more shade trees in strategic locations would provide savings equivalent to 

seven 100-megawatt power plants. The cost of peak load reduction was $63 per kW, 

considerably less than the $150 per kW benchmark for cost-effectiveness. Utility 

companies in the Temperate Interior West and throughout the country can invest in 

shade tree programs as a cost-effective energy conservation measure to lower peak 

energy demands.

Trees modify climate and conserve building energy use in three principal 

ways (fig. 3):

• Shading reduces the amount of heat absorbed and stored by built surfaces.

• Evapotranspiration converts liquid water to water vapor and thus cools the air 

by using solar energy that would otherwise result in heating of the air.

• Reducing windspeed reduces the infiltration of outside air into interior spaces 

and heat loss, especially where conductivity is relatively high (e.g., glass windows) (Simpson 1998).

Summer temperatures in cities can be 3 to 8 °F warmer than temperatures in 

the surrounding countryside. This is known as the urban heat island effect. Trees 

and other vegetation can combat this warming effect at small and large scales. On 

individual building sites, trees may lower air temperatures up to 5 °F compared 

with outside the greenspace. At larger scales (6 mi2), temperature differences of 

more than 9 °F have been observed between city centers and more vegetated suburban areas (Akbari et al. 1992). A recent study by scientists at National Aeronautics 

How trees work to 

save energy

Trees lower 

temperatures
GENERAL TECHNICAL REPORT PSW-GTR-206 

and Space Administration and Columbia University found that street trees provide 

the “greatest cooling potential per unit area” (Rosenzweig et al. 2006).

For individual buildings, strategically placed trees can increase energy efficiency in the summer and winter. Because the summer Sun is low in the east and 

west for several hours each day, solar angles should be considered (fig. 4). Trees 

that shade east and, especially, west walls help keep buildings cool. In the winter, 

allowing sunlight to strike the southern side of a building can warm interior spaces. 

However, the trunks and bare branches of deciduous trees that shade south- and 

east-facing walls during winter may increase heating costs by blocking 40 percent 

or more of winter sun (McPherson 1984).

Rates at which outside air infiltrates a building can increase substantially with 

windspeed. In cold, windy weather, the entire volume of air, even in newer or 

tightly sealed homes, may change every 2 to 3 hours. Windbreaks reduce windspeed and resulting air infiltration by up to 50 percent, translating into potential 

annual heating savings of 10 to 12 percent (Heisler 1986). Reductions in windspeed 

reduce heat transfer through conductive materials as well. Cool winter winds, blowing against windows, can contribute significantly to the heating load of buildings 

by increasing the gradient between inside and outside temperatures. Windbreaks 

reduce air infiltration and conductive heat loss from buildings. If located correctly, 

Figure 3—Trees save energy for heating and cooling by shading buildings, lowering summertime 

temperatures, and reducing windspeeds. Secondary benefits from energy conservation are reduced 

water consumption and reduced pollutant emissions by power plants (drawing by Mike Thomas).

Trees increase home 

energy efficiency and 

save money

Windbreaks reduce 

heat loss
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

trees planted as windbreaks can also serve as living snowfences, storing and directing the movement of snow (for more information see Brandle and Nickerson 1996).

Trees provide greater energy savings in the Temperate Interior West than 

in milder climate regions because they can have greater effects during the hot 

summers and cold winters. In Denver, for example, trees were found to produce 

substantial cooling savings for an energy-efficient two-story wood-frame house 

(McPherson et al. 1993). A typical energy-efficient house with air conditioning 

requires about $103 each year for cooling. A computer simulation demonstrated that 

three 25-ft tall trees—two on the west side of the house and one on the east—would 

save $35 each year for cooling, a 34-percent reduction (438 kWh). 

A recent study of the municipal trees of Boise states that the 23,000 trees save 

city residents approximately $180,000 in annual air conditioning costs and $143,000 

in heating costs (Peper et al., in press) or $13.88 per tree. The largest trees provide 

the largest benefits; the large silver maple (see “Common and Scientific Names” 

section), for example, accounts for 21 percent of the energy benefits although it represents only 8 percent of the population. In Reno, Nevada, early morning sunshine 

from the east can increase temperatures inside a home by as much as 20 °F in only 

a few hours. Carefully planted trees can help mitigate this effect and keep temperatures lower throughout the day (Post 2007).

Figure 4—Paths of the sun on winter and summer solstices (from Sand 1991). Summer heat gain is 

primarily through east- and west-facing windows and walls. The roof receives most irradiance, but 

insulated attics reduce heat gain to living spaces. The winter sun, at a lower angle, strikes the southfacing surfaces.

Retrofit for more 

savings
GENERAL TECHNICAL REPORT PSW-GTR-206 

Conserving energy by greening our cities is important because it can be more 

cost-effective than building new power plants (for more information, see the Center 

for Urban Forest Research’s research summaries “Green Plants or Power Plants?” 

and “Save Dollars with Shade” [Geiger 2001, 2002a]). In the Temperate Interior 

West region, there is ample opportunity to “retrofit” communities with more 

sustainable landscapes through strategic tree planting and care of existing trees.

Reducing Atmospheric Carbon Dioxide

Global temperatures have increased since the late 19th century, with major warming 

periods from 1910 to 1945 and from 1976 to the present (IPCC 2001). Human activities, primarily fossil-fuel consumption, are adding greenhouse gases to the atmosphere, and current research suggests that the recent increases in temperature can 

be attributed in large part to increases in greenhouse gases (IPCC 2001). Higher 

global temperatures are expected to have a number of adverse effects, including 

increasing the number and extent of wildfires, an aspect of particular concern in 

parts of the Temperate Interior West (McKenzie et al. 2004). Increasing frequency 

of extreme weather events will continue to tax emergency management resources.

Urban forests have been recognized as important storage sites for carbon 

dioxide (CO2), the primary greenhouse gas (Nowak and Crane 2002). Private markets dedicated to reducing CO2 emissions by trading carbon credits are emerging 

(Chicago Climate Exchange 2007, CO2e.com 2007, McHale 2003). Carbon credits 

have sold for as much as EUR 33 per ton (about $40; European Climate Exchange 

2006), and the social costs of CO2 emissions (an estimate of the monetary value of 

worldwide damage done by anthropogenic CO2 emissions) are estimated to range 

from £4 to £27 per ton ($7 to $47 per ton) (Pearce 2003). For comparison, for 

every $20 spent on a tree planting project in Arizona, 1 ton of atmospheric CO2

was reduced (McPherson and Simpson 1999). As carbon trading markets become 

accredited and prices rise, these markets could provide monetary resources for 

community forestry programs.

Urban forests can reduce atmospheric CO2 in two ways (fig. 5):

• Trees directly sequester CO2 in their stems and leaves while they grow.

• Trees near buildings can reduce the demand for heating and air conditioning, 

thereby reducing emissions associated with power production.

At the same time, the positive impact of trees on CO2 is offset by some emissions. To provide a complete picture of atmospheric CO2 reductions from tree 

plantings, it is important to consider CO2 released into the atmosphere through tree 

planting and care activities, as well as decomposition of wood from pruned or dead 

trees. During the process of planting and maintaining trees, vehicles, chain saws, 

Trees reduce CO2

Some tree-related 

activities release CO2
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting



chippers, and other equipment release CO2 (fig. 5). Typically, CO2 released from 

tree planting, maintenance, and other tree-related activities is about 2 to 8 percent 

of annual CO2 reductions obtained through sequestration and reduced power plant 

emissions (McPherson and Simpson 1999). And eventually, all trees die, and most 

of the carbon that has accumulated in their structure is released into the atmosphere 

as CO2 through decomposition. The rate of release into the atmosphere depends on 

if and how the wood is reused. For instance, recycling of urban wood waste into 

products such as furniture can delay the rate of decomposition compared to its 

reuse as mulch. Tree waste can also be used as a fuel source to generate electricity. 

Figure 5—Trees sequester CO2 as they grow and indirectly reduce CO2 emissions from power plants 

through energy conservation. At the same time, CO2 is released through decomposition and tree care 

activities that involve fossil-fuel consumption (drawing by Mike Thomas).
10

GENERAL TECHNICAL REPORT PSW-GTR-206 

If this biomass fuel replaces a more carbon-intensive form of electricity production, 

there will be an overall reduction in atmospheric CO2. 

Regional variations in climate and the mix of fuels that produce energy to heat 

and cool buildings influence potential CO2 emission reductions. The average emission rate in Boise, Idaho, is less than 1 lb of CO2 per MWh (US EPA 2003), a very 

small amount, because 99.9 percent of Boise’s power is generated hydroelectrically. 

Reno, Nevada, on the other hand, has an average emission of 1,861 lbs of CO2 per 

MWh (US EPA 2003) because its power comes mainly from coal and natural gas. 

Cities in the Temperate Interior West with relatively high CO2 emission rates will 

see greater benefits from reduced energy demand relative to other areas with lower 

emissions rates.

A study of the municipal trees of Boise found that the 23,000 publicly owned 

trees sequester about 1,121 tons of CO2 (Peper et al., in press) annually. Approximately 215 tons of CO2 is released from decaying trees and during maintenance, 

with a positive net reduction in atmospheric CO2 owing to trees of 906 tons.

Another study in Chicago focused on the carbon sequestration benefit of 

residential tree canopy. Tree canopy cover in two residential neighborhoods was 

estimated to sequester on average 0.112 lb/ft2, and pruning activities released 0.016 

lb/ft2 (Jo and McPherson 1995). Net annual carbon uptake was 0.096 lb/ft2. 

Grass-roots tree-planting efforts to reduce atmospheric CO2 can be very 

successful. Since 1990, Trees Forever, an Iowa-based nonprofit organization, 

has planted trees for energy savings and atmospheric CO2 reduction with utility 

sponsorships. Over 1 million trees have been planted in 400 communities with 

the help of 120,000 volunteers. These trees are estimated to offset CO2 emissions 

by 50,000 tons annually. Based on an Iowa State University study, survival rates 

are an amazing 91 percent indicating a highly trained and committed volunteer 

force (Ramsay 2002).

Improving Air Quality

Approximately 159 million people live in areas where ozone (O3) concentrations 

violate federal air quality standards. About 100 million people live in areas where 

dust and other small particulate matter (PM10) exceed levels for healthy air. Reno, 

Nevada, is among the cities listed in the U.S. EPA’s (Environmental Protection 

Agency) Green Book (US EPA 2006) as being in violation of federal air quality 

standards for particulate matter. Air pollution is a serious health threat to many city 

dwellers, causing asthma, coughing, headaches, respiratory and heart disease, and 

cancer (Smith 1990). Impaired health results in increased social costs for medical 

care, greater absenteeism, and reduced longevity.

Reduced CO2

emissions

CO2 reduction 

through community 

forestry

Trees improve air 

quality
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

11

Figure 6—Trees absorb gaseous pollutants, retain particles on their surfaces, and release oxygen and 

volatile organic compounds. By cooling urban heat islands and shading parked cars, trees can reduce 

ozone formation (drawing by Mike Thomas).

Recently, the EPA recognized tree planting as a measure in state implementation plans for reducing O3. Air quality management districts have funded tree planting projects to control particulate matter. These policy decisions are creating new 

opportunities to plant and care for trees as a method for controlling air pollution 

(Luley and Bond 2002; for more information see www.treescleanair.org [USDA FS 

2006b] and the Center for Urban Forest Research’s research summary “Trees—The 

Air Pollution Solution” [Geiger 2006]). 

Urban forests provide a number of air quality benefits:

• They absorb gaseous pollutants (e.g., O3, nitrogen dioxide [NO2], and sulfur 

dioxide [SO2]) through leaf surfaces (fig. 6).

• They intercept PM10 (e.g., dust, ash, pollen, smoke) (fig. 6).

• They release oxygen through photosynthesis.

• They transpire water and shade surfaces, which lowers air temperatures, 

thereby reducing O3 levels.

• They reduce energy use, which reduces emissions of pollutants from power plants, 

including NO2, SO2, PM10, and volatile organic compounds (VOCs) (fig. 6).

• They shade paved surfaces and parked cars, reducing hydrocarbon emissions 

(fig. 6).
12

GENERAL TECHNICAL REPORT PSW-GTR-206 

Trees may also adversely affect air quality. Most trees emit biogenic volatile 

organic compounds (BVOCs) such as isoprenes and monoterpenes that can contribute to O3 formation. The contribution of BVOC emissions from city trees to O3

formation depends on complex geographic and atmospheric interactions that have 

not been studied in most cities. Some complicating factors include variations with 

temperature and atmospheric levels of NO2.

A computer simulation study for Atlanta suggested that it would be very difficult to meet EPA ozone standards in the region by using trees because of the high 

BVOC emissions from native pines and other vegetation (Chameides et al. 1988). 

The results, however, were not straightforward. A later study showed that although 

removing trees reduced BVOC emissions, any positive effect was overwhelmed by 

increased hydrocarbon emissions from natural and anthropogenic sources owing 

to the increased air temperatures associated with tree removal (Cardelino and 

Chameides 1990). A similar finding was reported for the Houston-Galveston area, 

where deforestation associated with urbanization from 1992 to 2000 increased 

surface temperatures. Despite the decrease in BVOC emissions, O3 concentrations increased because of the enhanced urban heat island effect during simulated 

episodes (Kim et al. 2005). 

As well, the O3-forming potential of tree species differs considerably (Benjamin 

and Winer 1998). Trees emitting the greatest relative amount of BVOCs are sweetgum, blackgum, sycamore, poplar, and oak (Nowak 2000). In a study in the Los 

Angeles basin, increased planting of low-BVOC-emitting tree species was shown 

to reduce O3 concentrations, whereas planting of medium and high emitters would 

increase overall O3 concentrations (Taha 1996). A study in the Northeastern United 

States, however, found that species mix had no detectable effects on O3 concentrations (Nowak et al. 2000). Although new trees increased BVOC emissions, ambient 

VOC emissions were so high that additional BVOCs had little effect on air quality. 

These potentially negative effects of trees on one kind of air pollution must be 

considered in light of their great benefit in other areas.

Trees absorb gaseous pollutants through stomates, tiny openings in the leaves. 

Other methods of pollutant removal include adsorption of gases to plant surfaces 

and uptake through bark pores. Once gases enter the leaf they diffuse into intercellular spaces, where some react with inner leaf surfaces and others are absorbed by 

water films to form acids. Pollutants can damage plants by altering their metabolism and growth. At high concentrations, pollutants cause visible damage to leaves, 

such as spotting and bleaching (Costello and Jones 2003). Although some pollutants 

may pose health hazards to plants, pollutants such as nitrogenous gases can also be 

sources of essential nutrients for them.

Trees influence 

ozone formation

Trees absorb 

gaseous pollutants
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

13

Trees intercept small airborne particles. Some particles that are intercepted by 

a tree are absorbed, but most adhere to plant surfaces. Species with hairy or rough 

leaf, twig, and bark surfaces are efficient interceptors (Smith and Dochinger 1976). 

Intercepted particles are often resuspended to the atmosphere when wind blows the 

branches, and rain will wash some particulates off plant surfaces. The ultimate fate 

of these pollutants depends on whether they fall onto paved surfaces and enter the 

stormwater system, or fall on pervious surfaces, where they are filtered in the soil.

Trees near buildings can reduce the demand for heating and air conditioning, 

thereby reducing emissions of PM10, SO2, NO2, and VOCs associated with electric 

power production, an effect that can be sizable. For example, a strategically located 

tree can save 100 kWh in electricity for cooling annually (McPherson and Simpson 

1999, 2002, 2003). Assuming that this conserved electricity comes from a typical 

new coal-fired power plant in the Temperate Interior West, the tree reduces emissions of SO2 by 1.25 lb, NO2 by 0.39 lb (US EPA 2003), and PM10 by 0.84 lb (US 

EPA 1998). The same tree is responsible for conserving 60 gal of water in cooling 

towers and reducing CO2 emissions by 200 lb.

In the nearby Willamette/Lower Columbia River Valley of Washington and 

Oregon, the tree canopy over nearly 8 million acres was estimated to remove 

178 million lbs of air pollutants annually with a value of $419 million (American 

Forests 2001). A substantial decline in overall canopy cover from 46 percent in 

1972 to 24 percent in 2001 owing to increased development has meant a corresponding decline in air quality benefits, which were estimated retrospectively 

(in today’s dollars) at $719 million for 1972. Chicago’s 50.8 million trees were 

estimated to remove 234 tons of PM10, 210 tons of O3, 93 tons of SO2, and 17 

tons of carbon monoxide in 1991. This environmental service was valued at $9.2 

million (Nowak 1994). 

Trees in a Davis, California, parking lot were found to improve air quality by 

reducing air temperatures 1 to 3 °F (Scott et al. 1999). By shading asphalt surfaces 

and parked vehicles, trees reduce hydrocarbon emissions (VOCs) from gasoline that 

evaporates out of leaky fuel tanks and worn hoses (for more information, see our 

research summary “Where Are All the Cool Parking Lots?” [Geiger 2002b]). These 

evaporative emissions are a principal component of smog, and parked vehicles are a 

primary source (fig. 7). In California, parking-lot tree plantings can be funded as an 

air quality improvement measure because of the associated reductions in evaporative emissions.

Reducing Stormwater Runoff and Improving Hydrology

Urban stormwater runoff is a major source of pollution entering wetlands, streams, 

lakes, and oceans. Healthy trees can reduce the amount of runoff and pollutants 

Trees intercept 

particulate matter

Shade from trees 

prevents evporative 

hydrocarbon 

emission
14

GENERAL TECHNICAL REPORT PSW-GTR-206 

in receiving waters (Cappiella et al. 2005). This is important because federal law 

requires states and localities to control nonpoint-source pollution, such as runoff 

from pavements, buildings, and landscapes. Trees are mini-reservoirs, controlling 

runoff at the source, thereby reducing runoff volumes and erosion of watercourses, 

as well as delaying the onset of peak flows. Trees can reduce runoff in several ways 

(fig. 8; for more information, see our research summary “Is All Your Rain Going 

Down the Drain?” [Geiger 2003]):

• Leaves and branch surfaces intercept and store rainfall, thereby reducing runoff 

volumes and delaying the onset of peak flows.

• Roots reduce soil compaction, increasing the rate at which rainfall infiltrates 

soil and the capacity of soil to store water, reducing overland flow.

• Tree canopies reduce soil erosion by diminishing the impact of raindrops on 

barren surfaces.

• Transpiration through tree leaves reduces moisture levels in the soil, increasing the soil’s capacity to store rainfall.

Rainfall that is stored temporarily on canopy leaf and bark surfaces is called 

intercepted rainfall. Intercepted water evaporates, drips from leaf surfaces, and 

flows down stem surfaces to the ground. Tree surface saturation generally occurs 

after 1 to 2 in of rain has fallen (Xiao et al. 2000). During large storm events, rainFigure 7—Trees planted to shade parking areas can reduce hydrocarbon emissions and improve 

air quality.

Trees reduce runoff
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

15

fall exceeds the amount that the tree crown can store, about 50 to 100 gal per tree. 

The interception benefit is the amount of rainfall that does not reach the ground 

because it evaporates from the crown. As a result, the volume of runoff is reduced 

and the time of peak flow is delayed. Trees protect water quality by substantially 

reducing runoff during small rainfall events that are responsible for most pollutant 

washoff. Therefore, urban forests generally produce more benefits through water 

quality protection than through flood control (Xiao et al. 1998, 2000).

The amount of rainfall trees intercept depends on their architecture, rainfall 

patterns, and climate. Tree-crown characteristics that influence interception are 

the trunk, stem, and surface areas, textures, area of gaps, period when leaves are 

Figure 8—Trees intercept a portion of rainfall that evaporates and never reaches the ground. Some 

rainfall runs to the ground along branches and stems (stemflow) and some falls through gaps or drips 

off leaves and branches (throughfall). Transpiration increases soil moisture storage potential (drawing by Mike Thomas).
16

GENERAL TECHNICAL REPORT PSW-GTR-206 

present, and dimensions (e.g., tree height and diameter). Trees with coarse surfaces retain more rainfall than those with smooth surfaces. Large trees generally 

intercept more rainfall than small trees do because greater surface areas allow for 

greater evaporation rates. Tree crowns with few gaps reduce throughfall to the 

ground. Species that are in leaf when rainfall is plentiful are more effective than 

deciduous species that have dropped their leaves during the rainy season.

Studies that have simulated urban forest effects on stormwater runoff have 

reported reductions of 2 to 7 percent. Annual interception of rainfall by Sacramento’s urban forest for the total urbanized area was only about 2 percent because 

of the winter rainfall pattern and sparsity of evergreen species (Xiao et al. 1998). 

However, average interception in canopied areas ranged from 6 to 13 percent (150 

gal per tree), similar to values reported for rural forests. Broadleaf evergreens and 

conifers intercept more rainfall than deciduous species in areas where rainfall is 

highest in fall, winter, or spring (Xiao and McPherson 2002).

In Albuquerque, a city with approximately half the rainfall of the Temperate 

Interior West region, the canopy of the 21,000 municipal park trees reduced runoff 

by more than 11 million gal, with an estimated value of $56,000 (Vargas et al. 

2006). In contrast, in Montgomery, Alabama, a city with about half as many people 

but many more trees and approximately 50 in more rain than Albuquerque, the tree 

canopy was estimated to reduce runoff by 1.7 billion gal, valued at $454 million per 

20-year construction cycle (American Forests 2004). According to a recent study, 

the 23,000 municipal trees of Boise, Idaho, were estimated to intercept approximately 19.2 million gal of stormwater annually, with an estimated value of $96,000 

(Peper et al., in press).

Urban forests can provide other hydrologic benefits, too. For example, tree plantations, nurseries, or landscapes can be irrigated with partially treated wastewater. 

Infiltration of water through the soil can be a safe and productive means of water 

treatment. Reused wastewater applied to urban forest lands can recharge aquifers, 

reduce stormwater-treatment loads, and create income through sales of nursery 

or wood products. Recycling urban wastewater into greenspace areas can be an 

economical means of treatment and disposal while at the same time providing other 

environmental benefits (USDA NRCS 2005).

Aesthetics and Other Benefits

Trees provide a host of aesthetic, social, economic, and health benefits that 

should be included in any benefit-cost analysis. One of the most frequently cited 

reasons that people plant trees is for beautification. Trees add color, texture, line, 

and form to the landscape, softening the hard geometry that dominates built 

Urban forests can 

treat wastewater

Beautification
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

17

environments. Research on the aesthetic quality of residential streets has shown 

that street trees are the single strongest positive influence on scenic quality 

(Schroeder and Cannon 1983).

In surveys, consumers have shown greater preference for commercial 

streetscapes with trees. In contrast to areas without trees, shoppers shop more often 

and longer in well-landscaped business districts. They are willing to pay more for 

parking and up to 11 percent more for goods and services (Wolf 1999).

Research in public housing complexes found that outdoor spaces with trees 

were used significantly more often than spaces without trees. By facilitating 

interactions among residents, trees can contribute to reduced levels of domestic 

violence, as well as foster safer and more sociable neighborhood environments 

(Sullivan and Kuo 1996).

Well-maintained trees increase the “curb appeal” of properties (fig. 9). Research 

documenting the increase in dollar value that can be attributed to trees is difficult 

to conduct and is still in early stages, but some studies comparing sales prices of 

residential properties having different numbers of trees have suggested that people 

are willing to pay 3 to 7 percent more for properties with ample trees versus few or 

no trees. One of the most comprehensive studies of the influence of trees on home 

property values was based on actual sales prices and found that each large frontyard tree was associated with about a 1-percent increase in sales price (Anderson 

and Cordell 1988). A much greater value of 9 percent ($15,000) was determined 

Figure 9—Trees beautify a neighborhood, increasing property values and creating a more sociable 

environment.

Brian Jorgenson

Attractiveness of 

retail settings

Public safety benefits

Property value 

benefits
18

GENERAL TECHNICAL REPORT PSW-GTR-206 

in a U.S. Tax Court case for the loss of a large black oak on a property valued at 

$164,500 (Neely 1988). Depending on average home sales prices, the value of this 

benefit can contribute significantly to cities’ property tax revenues.

Scientific studies confirm that trees in cities provide social and psychological 

benefits. Humans derive substantial pleasure from trees, whether it is inspiration 

from their beauty, a spiritual connection, or a sense of meaning (Dwyer et al. 

1992, Lewis 1996). After natural disasters, people often report a sense of loss if 

their community forest has been damaged (Hull 1992). Views of trees and nature 

from homes and offices provide restorative experiences that ease mental fatigue 

and help people to concentrate (Kaplan and Kaplan 1989). Desk workers with a 

view of nature report lower rates of sickness and greater satisfaction with their 

jobs compared to those having no visual connection to nature (Kaplan 1992). Trees 

provide important settings for recreation and relaxation in and near cities. The act 

of planting trees can have social value, as bonds between people and local groups 

often result.

A series of studies on human stress caused by general urban conditions show 

that views of nature reduce the stress response of both body and mind (Parsons et 

al. 1998), improving general well-being. Urban green also appears to have a positive effect on the human immune system. Hospitalized patients who have views of 

nature and spend time outdoors need less medication, sleep better, have a better 

outlook, and recover more quickly than patients without connections to nature 

(Ulrich 1985). Skin cancer is a particular concern in the sunny Temperate Interior West region. By providing shade, trees reduce exposure to ultraviolet (UV) 

light, thereby lowering the risk of harmful effects from skin cancer and cataracts 

(Tretheway and Manthe 1999). At the latitudes of the Temperate Interior West, 

the ultraviolet protection factor provided by trees increases from approximately 2 

under a 30-percent canopy cover to approximately 15 under a 90-percent canopy 

cover (Grant et al. 2002). Because early exposure to UV radiation is a risk factor for 

later development of skin cancer, planting trees around playgrounds, schools, day 

care centers, and ball fields can be especially valuable in helping reduce the risk of 

later-life cancers. 

Certain environmental benefits from trees are more difficult to quantify than 

those previously described, but can be just as important. Noise can reach unhealthy 

levels in cities. Trucks, trains, and planes can produce noise that exceeds 100 

decibels (dB), twice the level at which noise becomes a health risk. Thick strips 

of vegetation in conjunction with landforms or solid barriers can reduce some 

highway noise and have a psychological effect (Cook 1978), but if vegetation is used 

as the only sound barrier, the amount necessary to achieve measurable reductions 

Social and 

psychological 

benefits

Human health 

benefits

Noise reduction
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

19

in noise (about 200 ft for a 10-dB reduction) may be impractical (U.S. Department of Transportation 1995). Other studies have shown that the performance of 

noise barriers is increased when used in combination with vegetative screens (van 

Rentergehm et al. 2002).

Numerous types of wildlife inhabit cities and are generally highly valued by 

residents. For example, older parks, cemeteries, and botanical gardens often contain 

a rich assemblage of wildlife. Remnant woodlands and riparian habitats within 

cities can connect a city to its surrounding bioregion (fig. 10). Wetlands, greenways 

(linear parks), and other greenspace can provide habitats that conserve biodiversity 

(Platt et al. 1994).

Urban forestry can provide jobs for both skilled and unskilled labor. Public 

service programs and grassroots-led urban and community forestry programs 

provide horticultural training to volunteers across the United States. Also, urban and 

community forestry provides educational opportunities for residents who want to 

learn about nature through firsthand experience (McPherson and Mathis 1999). Local 

nonprofit tree groups and municipal volunteer programs often provide educational 

material and hands-on training in the care of trees and work with area schools.

Tree shade on streets can help offset the cost of managing pavement by 

protecting it from weathering. The asphalt paving on streets contains stone 

aggregate in an oil binder. Tree shade lowers the street surface temperature and 

reduces heating and volatilization of the binder (McPherson and Muchnick 2005). 

As a result, the aggregate remains protected for a longer period by the oil binder. 

Figure 10—Natural areas within cities are refuges for wildlife and help connect city dwellers with 

their ecosystems.

Wildlife habitat

Jobs and 

environmental 

education

Shade can reduce 

street maintenance
20

GENERAL TECHNICAL REPORT PSW-GTR-206 

When unprotected, vehicles loosen the aggregate, and much like sandpaper, the 

loose aggregate grinds down the pavement. Because most weathering of asphaltconcrete pavement occurs during the first 5 to 10 years when new street tree 

plantings provide little shade, this benefit mainly applies when older streets are 

resurfaced (fig. 11). In snowier communities, the benefit from summer shade can be 

offset by winter shade that prolongs snow and ice accumulation, and may result in 

greater use of salt and sand. Further study is needed to evaluate the seasonal effects 

of tree shade on paving condition and safety.

Costs

The environmental, social, and economic benefits of urban and community forests 

come, of course, at a price. A national survey reported that communities in the 

Temperate Interior West region spent an average of about $6.39 per tree, in 1994, 

for street- and park-tree management (Tschantz and Sacamano 1994). This amount 

is relatively high, with only three national regions spending more than this and 

six regions spending less. Nationwide, the single largest expenditure was for tree 

pruning, followed by tree removal/disposal, and tree planting. The survey did not 

include non-tree-care costs, such as money spent on infrastructure repair, litigation, 

and cleanup.

Figure 11—Although shade trees can be expensive to maintain, their shade can reduce the costs 

of resurfacing streets (McPherson and Muchnick 2005), promote pedestrian travel, and improve 

air quality directly through pollutant uptake and indirectly through reduced emissions of volatile 

organic compounds from cars.

Brian Jorgenson

Muncipal costs of 

tree care
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

21

Our survey of municipal foresters in Boise, Lewiston, Nampa, Payette, and 

Caldwell, Idaho, and Carson City, Nevada, indicates that they are spending about 

$18 per tree annually. The greatest costs are for pruning ($5 to $7 per tree) and 

planting ($4 per tree). Removal and disposal ($2 to $3 per tree) and administration 

($3 per tree) are the next most costly.

Annual expenditures for tree management on private property have not been 

well documented. Costs differ considerably, ranging from some commercial or 

residential properties that receive regular professional landscape service to others 

that are virtually “wild” and without maintenance. Our survey of commercial 

arborists in the Temperate Interior West indicated that expenditures typically 

range from $8 to $11 per tree. Expenditures are usually greatest for pruning, 

planting, and removal.

Planting and Maintaining Trees 

Planting costs include the cost of the tree and the cost for planting, staking, and 

mulching. Based on our survey of Temperate Interior West municipal and commercial arborists, planting costs differ with tree size and range from $75 for a 1.5-in 

diameter at breast height (d.b.h.) tree to $250 for a 2-in d.b.h. tree. Pruning cycles 

differ by city and by tree size and range from once every 2 to 4 years for new trees 

to once in 5 to 10 years for large, mature trees. The cost for pruning young trees 

ranged from $25 to $50 for a public tree and from $35 to $45 for a yard tree; the 

cost to prune a large, mature tree was about $250 for public trees and ranged from 

$80 to $400 for yard trees. 

Because of the region’s hot and dry summer climate, most trees require irrigation throughout their lives, but because most are planted into areas that are already 

irrigated, such as parkways or other landscaped areas, the cost for additional water 

for the trees is negligible and is ignored for the purposes of this guide. Newly 

planted trees, however, require additional watering in early years to successfully 

establish themselves. The costs of irrigation for public trees are estimated at about 

$1.50 for the first 5 years, mainly for the labor costs involved in visiting the trees 

with a water truck or other time-intensive methods. No additional costs are included 

for establishment watering of yard trees, as the few minutes of labor necessary is 

considered negligible.

At the end of a tree’s life, removal costs can be substantial, especially for large 

trees. Removal and disposal of small trees (under 3 in d.b.h.) cost between $10 and 

$50, but a large tree may cost several thousand dollars to remove. According to our 

survey, total costs for removal of trees and stumps are approximately $34 per in 

d.b.h. for yard trees and $27 per in d.b.h. for public trees.

Residental costs 

differ
22

GENERAL TECHNICAL REPORT PSW-GTR-206 

Conflicts With Urban Infrastructure

Like other cities across the United States, communities in the Temperate Interior 

West region are spending millions of dollars each year to manage conflicts between 

trees and power lines, sidewalks, sewers, and other elements of the urban infrastructure. According to our survey, cities in the region are spending about $1 to $4 

per tree annually on sidewalk, curb, and gutter repair costs. This amount is far less 

than the $11.22 per tree reported for 18 California cities (McPherson 2000). In addition, the figures for California apply only to street trees and do not include repair 

costs for damaged sewer lines, building foundations, parking lots, and various other 

hardscape elements.

In some cities, decreasing budgets are increasing the sidewalk-repair backlog 

and forcing cities to shift the costs of sidewalk repair to residents. This shift has 

significant impacts on residents in older areas, where large trees have outgrown 

small sites and infrastructure has deteriorated. It should be noted that trees are not 

always fully responsible for these problems. In older areas, in particular, sidewalks 

and curbs may have reached the end of their 20- to 25-year service life, or may have 

been poorly constructed in the first place (Sydnor et al. 2000).

Efforts to control the costs of these conflicts are having alarming effects on 

urban forests (Bernhardt and Swiecki 1993, Thompson and Ahern 2000):

• Cities are downsizing their urban forests by planting smaller trees. Although 

small trees are appropriate under power lines and in small planting sites, they 

are less effective than large trees at providing shade, absorbing air pollutants, 

and intercepting rainfall.

• Thousands of healthy urban trees are lost each year and their benefits forgone 

because of sidewalk damage, the second most common reason that street and 

park trees were removed. 

• Most cities surveyed were removing more trees than they were planting. Residents 

forced to pay for sidewalk repairs may not want replacement trees.

Cost-effective strategies to retain benefits from large street trees while reducing 

costs associated with infrastructure conflicts are described in Reducing Infrastructure Damage by Tree Roots (Costello and Jones 2003). Matching the growth characteristics of trees to the conditions at the planting site is one important strategy. 

Tree roots can also damage old sewer lines that are cracked or otherwise 

susceptible to invasion. Sewer repair companies estimate that sewer damage is 

minor until trees and sewers are over 30 years old, and roots from trees in yards are 

usually more of a problem than roots from trees in planter strips along streets. The 

latter assertion may be because the sewers are closer to the root zone as they enter 

Tree roots can 

damage sidewalks

Costs of conflicts
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

23

houses than at the street. Repair costs typically range from $100 for sewer rodding 

(inserting a cleaning implement to temporarily remove roots) to $1,000 or more for 

sewer excavation and replacement.

Most communities sweep their streets regularly to reduce surface-runoff pollution entering local waterways. Street trees drop leaves, flowers, fruit, and branches 

year round that constitute a significant portion of debris collected from city streets. 

When leaves fall and rains begin, tree litter can clog sewers, dry wells, and other 

elements of flood-control systems. Costs include additional labor needed to remove 

leaves, and property damage caused by localized flooding. Wind and ice storms 

also incur cleanup costs.

The cost of addressing conflicts between trees and power lines is reflected in 

electric rates. Large trees under power lines require more frequent pruning than 

better suited trees, which can make large trees appear less attractive (fig. 12). 

Frequent crown reduction reduces the benefits these trees could otherwise provide. 

Moreover, increased costs for pruning are passed on to customers.

Figure 12—Large 

trees planted under 

power lines can require 

extensive pruning, which 

increases tree care costs 

and reduces the benefits 

of those trees, including 

their appearance.

Cleaning up after 

trees

Large trees under 

power lines can be 

costly
24

GENERAL TECHNICAL REPORT PSW-GTR-206 

The green infrastructure is a significant component of communities in the Interior West region. The urban tree 

canopy of Boise, Idaho is shown here.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

25

Chapter 3. Benefits and Costs of Community Forests in 

Temperate Interior West Communities

This chapter presents estimated benefits and costs for trees planted in typical 

residential yards and public sites. Because benefits and costs differ with tree size, 

we report results for representative small, medium, and large deciduous trees and 

for a representative conifer.

Estimates are initial approximations, as some benefits and costs are intangible 

or difficult to quantify (e.g., impacts on psychological health, crime, and violence). 

Limited knowledge about physical processes at work and their interactions makes 

estimates imprecise (e.g., fate of air pollutants trapped by trees and then washed 

to the ground by rainfall). Tree growth and mortality rates are highly variable 

throughout the region. Benefits and costs also differ, depending on differences in 

climate, pollutant concentrations, maintenance practices, and other factors. Given 

the Temperate Interior West region’s diverse landscape, with different climates, 

soils, and types of community forestry programs, the approach used here provides 

first-order approximations. It is a general accounting that can be easily adapted and 

adjusted for local planting projects. It provides a basis for decisions that set priorities and influence management direction (Maco and McPherson 2003).

Overview of Procedures

Approach

In this study, annual benefits and costs are estimated over a 40-year planning 

horizon for newly planted trees in three residential yard locations (east, south, and 

west of the residence) and a public streetside or park location (app. 2). Henceforth, 

we refer to trees in these hypothetical locations as “yard” trees and “public” trees, 

respectively. Prices are assigned to each cost (e.g., planting, pruning, removal, 

irrigation, infrastructure repair, liability) and benefit (e.g., heating/cooling energy 

savings, air pollutant mitigation, stormwater runoff reduction, and aesthetic and 

other benefits measured as increases in property value) through direct estimation 

and implied valuation of benefits as environmental externalities. This approach 

makes it possible to estimate the net benefits of plantings in “typical” locations by 

using “typical” tree species. More information on data collection, modeling procedures, and assumptions can be found in appendix 3.

To account for differences in the mature size and growth of different tree species, we report results for a small (crabapple), medium (Norway maple), and large 

(white ash) deciduous tree and a conifer (blue spruce) (figs. 13 to 16) (see “Common 

and Scientific Names” section). The conifer is assumed to be a windbreak tree 

located more than 50 ft from the residence so it does not shade the building. The 
26

GENERAL TECHNICAL REPORT PSW-GTR-206 

Figure 13—The crabapple represents small trees in this guide.

Brian Jorgenson

Figure 14—The Norway maple represents medium trees in this guide.

Brian Jorgenson
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

27

selection of these species is based on data availability and representative growth 

and is not intended to endorse their use in large numbers. In fact, white ash is 

susceptible to the emerald ash borer, which may become a serious threat to all ash 

trees in the region.

Tree dimensions are derived from growth curves developed from park and 

street trees in Boise, Idaho (Peper et al., in press) (fig. 17).

Frequency and costs of tree management are estimated based on surveys with 

municipal foresters from Boise, Lewiston, Nampa, Payette, and Caldwell, Idaho, 

and Carson City, Nevada. In addition, several commercial arborists from Boise 

and Meridian, Idaho, provided information on tree management costs on residential properties.

Benefits are calculated with numerical models and data both from the region 

(e.g., pollutant emission factors for avoided emissions from energy savings) and 

from local sources (e.g., Boise climate data for energy effects). Regional electricity 

and natural gas prices are used in this study to quantify energy savings. Damage 

costs and control costs are used to estimate willingness to pay. For example, the 

Figure 15—The white ash represents large trees in this guide.

Brian Jorgenson

Figure 16—The blue spruce represents coniferous trees in 

this guide.

Tree care costs 

based on survey 

findings

Tree benefits based 

on numerical models
28

GENERAL TECHNICAL REPORT PSW-GTR-206 

Figure 17—Tree growth curves are based on data collected from park trees in Boise, Idaho. Data for 

representative small, medium, large, and conifer trees are for the crabapple, Norway maple, white 

ash, and blue spruce, respectively. Differences in leaf surface area among species are most important 

for this analysis because functional benefits such as summer shade, rainfall interception, and pollutant uptake are related to leaf area.

value of stormwater runoff reduction owing to rainfall interception by trees is 

estimated by using marginal control costs. If a community or developer is willing 

to pay an average of $0.01 per gal of treated and controlled runoff to meet minimum standards, then the stormwater runoff mitigation value of a tree that intercepts 

1,000 gal of rainfall, eliminating the need for control, should be $10.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

29

Reporting Results

Results are reported in terms of annual value per tree planted. To make these 

calculations realistic, however, mortality rates are included. Based on our survey of 

regional municipal foresters and commercial arborists, this analysis assumes that 

43 percent of the planted trees will die over the 40-year period. Annual mortality 

rates are 2.6 percent per year for the first 5 years and 0.85 percent per year for the 

remainder of the 40-year period. This accounting approach “grows” trees in different locations and uses computer simulation to calculate the annual flow of benefits 

and costs as trees mature and die (McPherson 1992). In appendix 2, results are 

reported at 5-year intervals for 40 years.

Findings of This Study

Average Annual Net Benefits

Average annual net benefits (benefits minus costs) per tree over a 40-year period 

increase with mature tree size (for detailed results see app. 2):

• $12 to $24 for a small tree

• $29 to $45 for a medium tree

• $47 to $63 for a large tree

• $22 to $25 for a conifer

Our findings demonstrate that average annual net benefits from large trees 

like the white ash are substantially greater than those from small trees like the 

crabapple. Average annual net benefits for the small, medium, and large deciduous 

public trees are $12, $30, and $49, respectively. Conifers provide an intermediate 

level of benefits, on average $22 for a public tree. The largest average annual net 

benefits, however, stem from yard trees opposite the west-facing wall of a house: 

$24, $45, $63, and $25, for small, medium, and large deciduous trees and the 

conifer, respectively.

At year 40, the large yard tree opposite a west wall produces a net annual 

benefit of $69. In the same location, 40 years after planting, the crabapple, Norway 

maple, and blue spruce produce annual net benefits of $35, $57, and $34. Forty years 

after planting at a typical public site, the small, medium, and large deciduous trees 

and the conifer provide annual net benefits of $18, $39, $50, and $28, respectively.

Net benefits for a yard tree opposite a west house wall and a public tree also 

increase with size when summed over the entire 40-year period:

• $953 (yard) and $479 (public) for a small tree

• $1,784 (yard) and $1,184 (public) for a medium tree

Tree mortality 

included

Average annual net 

benefits increase 

wtih tree size

Large trees provide 

the most benefits

Net benefits summed 

over 40 years
30

GENERAL TECHNICAL REPORT PSW-GTR-206 

• $2,497 (yard) and $1,931 (public) for a large tree

• $984 (yard) and $840 (public) for a conifer

Even just 20 years after planting, average annual benefits for all trees exceed 

costs of tree planting and management (tables 1 and 2). For a large white ash in a 

yard 20 years after planting, the total value of environmental benefits alone ($51) 

is more than 10 times the total annual cost ($5). Environmental benefits total $24, 

$41, and $23 for the crabapple, Norway maple, and blue spruce, and tree care costs 

are comparable across species, $5, $5, and $3, respectively. Adding the value of 

aesthetics and other benefits to the environmental benefits results in even greater 

net benefits.

Net benefits for public trees at 20 years ($20, $36, $69, and $26 for small, 

medium, and large deciduous trees and the conifer; table 2) are less than yard trees 

($32, $53, $85, and $31) for two main reasons: public tree care costs are greater 

because public trees generally receive more intensive care than private trees; and 

energy benefits are lower for public trees than for yard trees because public trees 

are assumed to provide general climate effects, but not to shade buildings directly. 

Average Annual Costs

Averaged over 40 years, the costs for yard and public trees, respectively, are as follows:

• $8 and $16 for a small tree

• $10 and $18 for a medium tree

• $11 and $19 for a large tree

• $7 and $12 for a conifer

Annualized over the 40-year period, tree planting is the single greatest cost 

for yard trees, averaging $4 per tree per year (see app. 2). Based on our survey, we 

assume in this study that a 2-in diameter at breast height (d.b.h.) yard tree is planted 

at a cost of $175. The cost for planting a 2-in d.b.h. public tree is $140. For public 

trees, where safety is particularly important and conflicts with infrastructure are 

greater, pruning is the greatest cost, with average annual costs of $1 to $7. Annual 

pruning costs for yard trees are also significant at $1 to $4. Removal and disposal 

costs, annualized over 40 years, average $2 to $3 per tree. At $2 to $3 per tree per 

year, administrative costs are significant for public trees.

Table 3 shows annual management costs 20 years after planting for yard trees 

to the west of a house and for public trees. Annual costs for yard trees range from 

$3 to $5, and public tree care costs are $9 to $14. In general, public trees are more 

expensive to maintain than yard trees because of their prominence and because of 

the greater need for public safety.

Year 20 

environmental 

benefits exceed tree 

care costs

Costs of tree care
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

31

Table 1—Estimated annual benefits and costs for a private tree (residential yard) opposite the west-facing 

wall 20 years after planting

Crabapple 

small tree 

20 ft tall 

23-ft spread 

LSA = 1,039 ft2

 

Norway maple

medium tree 

35 ft tall 

29-ft spread 

LSA = 2,114 ft2

 

White ash 

large tree 

39 ft tall 

34-ft spread 

LSA = 3,376 ft2

 

Blue spruce 

conifer tree 

28 ft tall 

20-ft spread 

LSA = 1,331 ft2

Benefit category

Resource 

units

Total 

value

Resource 

units

Total 

value

Resource 

units

Total 

value

Resource 

units

Total 

value

Dollars Dollars Dollars Dollars

Electricity savings ($0.0820/kWh) 179 kWh 14.68 329 kWh 26.97 395 kWh 32.42 71.4 kWh 5.85

Natural gas savings ($1.17/therm) 6.26 therms 7.30 6.99 therms 8.16 9.17 therms 10.69 7.69 therms 8.97

Carbon dioxide ($0.00334/lb) 260 lb 0.87 412 lb 1.38 466 lb 1.55 161.3 lb 0.54

Ozone ($0.51/lb) 0.18 lb 0.09 0.28 lb 0.14 0.62lb 0.32 0.21 lb 0.11

Nitrogen dioxide ($0.51/lb) 0.33 lb 0.17 0.53 lb 0.27 0.71 lb 0.36 0.24 lb 0.12

Sulfur dioxide ($0.06 /lb) 0.65 lb 0.04 1.16 lb 0.07 1.45lb 0.09 0.37 lb 0.02

Small particulate matter ($0.92/lb) 0.18 lb 0.17 0.25 lb 0.23 0.48lb 0.44 0.16 lb 0.15

Volatile organic compounds ($0.14/lb) 0.06 lb 0.01 0.10 lb 0.01 0.13lb 0.02 0.04 lb 0

Biogenic volatile organic compounds 

($0.14/lb) 0 lb 0 -0.14 lb -0.02 0 lb 0 -1.34 lb -0.19

Rainfall interception ($0.005/gal) 142 gal 0.71 796 gal 3.98 993 gal 4.96 1,390 gal 6.95

Environmental subtotal 24.04 41.19 50.86 22.54

Other benefits 12.60 16.68 39.37 11.12

Total benefits 36.63 57.87 90.24 33.66

Total costs 4.58 5.12 5.20 2.91

Net benefits 32.05 52.74 85.04 30.74

LSA = leaf surface area.

Table 2—Estimated annual benefits and costs for a public tree (street/park) 20 years after planting

Crabapple 

small tree 

20 ft tall 

23-ft spread 

LSA = 1,039 ft2

Norway maple

medium tree

35 ft tall

29-ft spread

LSA = 2,114 ft2

White ash

large tree

39 ft tall

34-ft spread

LSA = 3,376 ft2

Blue spruce

conifer tree

28 ft tall

20-ft spread

LSA = 1,331 ft2

Benefit category

Resource 

units

Total 

value

Resource 

units

Total 

value

Resource 

units

Total 

value

Resource 

units

Total 

value

Dollars Dollars Dollars Dollars

Electricity savings ($0.0820/kWh) 99 kWh 5.19 329 kWh 26.97 395 kWh 32.42 71.4 kWh 5.85

Natural gas savings ($1.17/therm) 7.47 therms 8.72 10.46 therms 12.20 12.67 therms 14.78 7.69 therms 8.97

Carbon dioxide ($0.00334/lb) 215 lb 0.63 412 lb 1.38 466 lb 1.55 161.3 lb 0.54

Ozone ($0.51/lb) 0.18 lb 0.15 0.28 lb 0.14 0.62 lb 0.32 0.21 lb 0.11

Nitrogen dioxide ($0.51/lb) 0.33 lb 0.30 0.53 lb 0.27 0.71 lb 0.36 0.24 lb 0.12

Sulfur dioxide ($0.06 /lb) 0.65 lb 0.57 1.16 lb 0.07 1.45 lb 0.09 0.37 lb 0.02

Small particulate matter ($0.92/lb) 0.18 lb 0.29 0.25 lb 0.23 0.48 lb 0.44 0.16 lb 0.15

Volatile organic compounds ($0.14/lb) 0.06 lb 0.02 0.10 lb 0.01 0.13 lb 0.02 0.04 lb 0

Biogenic volatile organic compounds 

($0.14/lb) 0 lb - 0.27 -0.14 lb -0.02 0 lb 0 -1.34 lb -0.19

Rainfall interception ($0.005/gal) 142 gal 1.30 796 gal 3.98 993 gal 4.96 1,390 gal 6.95

Environmental subtotal 10.74 41.19 50.86 22.54

Other benefits 2.75 16.68 39.37 11.12

Total benefits 13.49 57.87 90.24 33.66

Total costs 12.50 14.14 14.37 8.68

Net benefits 20.3535.52 68.94 26.27

LSA = leaf surface area.
32

GENERAL TECHNICAL REPORT PSW-GTR-206 

Average Annual Benefits

Average annual benefits, including stormwater reduction, aesthetic value, air quality improvement and carbon dioxide (CO2) sequestration increase with mature tree 

size (figs. 18 and 19; for detailed results see app. 2):

• $25 to $32 for a small tree

• $39 to $55 for a medium tree

• $58 to $74 for a large tree

• $32 to $33 for a conifer

Energy Savings—

Energy benefits are greatest and tend to increase with mature tree size. For example, average annual net energy benefits over the 40-year period are $21 for the small 

crabapple tree opposite a west-facing wall, and $39 for the larger white ash. For 

species of all sizes, energy savings increase as trees mature and their leaf surface 

area increases (figs. 18 and 19).

Table 3—Estimated annual costs 20 years after planting for a private tree opposite the west-facing wall and a 

public tree

Crabapple 

small tree 

20 ft tall 

23-ft spread 

LSA = 1,039 ft2

Norway maple 

medium tree 

35 ft tall 

29-ft spread 

LSA = 2,114 ft2

White ash 

large tree 

39 ft tall 

34-ft spread 

LSA = 3,376 ft2

Blue spruce

 conifer tree

 28 ft tall

 20-ft spread 

LSA = 1,331 ft2

Costs

Private: 

west

Public 

tree

Private: 

west

Public 

tree

Private: 

west

Public 

tree

Private: 

west

Public 

tree

Dollars per tree per year

Pruning 2.30 5.56 2.30 5.56 2.30 5.56 0.23 0.56

Remove and dispose 1.87 2.23 2.31 2.75 2.37 2.83 2.19 2.61

Pest and disease 0.15 0.13 0.18 0.15 0.19 0.16 0.17 0.15

Infrastructure 0.21 1.40 0.25 1.73 0.26 1.77 0.24 1.64

Cleanup 0.06 0.41 0.07 0.50 0.08 0.52 0.07 0.48

Liability and legal 0.01 0.04 0.01 0.05 0.01 0.06 0.01 0.05

Admin. and other 0 2.74 0 3.39 0 3.48 0 3.21

Total costs 4.58 12.50 5.12 14.14 5.20 14.37 2.91 8.68

Total benefits 36.63 32.85 57.87 49.66 90.24 83.30 33.66 34.96

Total net benefits 32.05 20.35 52.74 35.52 85.04 68.94 30.74 26.27

Note: Prices for removal and disposal are included to account for expected mortality of citywide planting.

LSA = leaf surface area.

Energy benefits are 

greatest
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

33

Figure 18— Estimated annual benefits and costs for a small 

(apple), medium (Norway maple), and large (white ash) deciduous tree, and a conifer (blue spruce) located west of a residence. 

Costs are greatest during the initial establishment period whereas 

benefits increase with tree size.

Figure 19— Estimated annual benefits and costs for public small 

(apple), medium (Norway maple), and large (white ash) deciduous 

tree, and a conifer (blue spruce).
34

GENERAL TECHNICAL REPORT PSW-GTR-206 

As might be expected in a region with hot, dry summers and cold winters, 

both cooling and heating savings are substantial. Trees planted on the west side 

of buildings have the greatest total energy benefits because the effect of shade on 

cooling costs is maximized without blocking the warming rays of the winter sun. A 

yard tree located south of a home produced the least total energy benefit because it 

had the least benefit during the summer and the greatest adverse effect from shade 

on heating costs in winter. Trees located east of a building provided intermediate 

benefits. Total energy benefits also reflect species-related traits such as size, form, 

branch pattern, and density, as well as time in leaf.

Average annual total energy benefits for public trees were less than for yard 

trees and ranged from $14 for the blue spruce to $30 for the large white ash.

Aesthetic and Other Benefits—

Aesthetic and other benefits reflected in property values account for a significant 

portion of total benefits. As trees grow and become more visible, they can increase 

a property’s sales price. Annual values averaged over 40 years associated with these 

aesthetic and other benefits for yard trees are $9, $16, $26, and $10 for the small, 

medium, and large deciduous trees and for the conifer, respectively. The values for 

public trees are $10, $18, $29, and $12, respectively. The values for yard trees are 

slightly less than for public trees because off-street trees contribute less to a property’s curb appeal than more prominent street trees. Because our estimates are based 

on median home sale prices, the effects of trees on property values and aesthetics 

will differ depending on local economies.

Stormwater Runoff Reduction—

By intercepting rain and snow before it reaches the stormwater treatment system, 

trees can have a valuable effect on reducing runoff. The white ash intercepts 1,111 

gal per year on average over a 40-year period with an implied value of $6. The 

crabapple, Norway maple, and blue spruce intercept 161, 893, and 1,459 gal per year 

on average, with values of $1, $4, and $7, respectively. Forty years after planting, 

average stormwater runoff reductions equal 309, 1,663, 2,102, and 2,463 for the 

small, medium, and large deciduous trees and the conifer, respectively.

As the cities of the Temperate Interior West continue to grow, the amount of 

impervious surface will continue to increase dramatically. The role that trees, in 

combination with other strategies such as rain gardens and structural soils, can play 

in reducing stormwater runoff is substantial. 

Air Quality Improvement—

Air quality benefits are defined as the sum of pollutant uptake by trees and avoided 

power plant emissions from energy savings minus biogenic volatile organic 

Aesthetic benefits 

are substantial
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

35

compounds (BVOCs) released by trees. Average annual air quality benefits 

over the 40-year period were approximately $1 per tree. These relatively low air 

quality benefits reflect the clean air of most cities in the Temperate Interior West 

region. The benefits in terms of avoided emissions, for instance, are quite low, 

because much of the energy in the region is produced from clean sources such as 

hydroelectric plants. Contrast these results with the air quality benefits of a large 

tree in the Northeast region ($13; McPherson et al., in press), Midwest region ($7.65; 

McPherson et al. 2006c), and southern California ($28.38; McPherson 2000).

The ability of trees to intercept particulate matter (PM10) from the air is 

the most highly valued. Over 40 years, the white ash, for example, is estimated 

to reduce an average of 0.59 lb of PM10 from the air annually, valued at $0.54. 

Average annual reductions in nitrogen dioxide, ozone, sulfur dioxide, and 

volatile organic compounds for the large tree are valued at $0.35, $0.36, $0.08, 

and $0.02, respectively.

Forty years after planting, the average annual monetary values of air quality 

improvement for the crabapple tree, Norway maple, white ash, and blue spruce are 

$0.80, $1.21, $2.50, and $0.11, respectively.

Carbon Dioxide Reduction—

Net atmospheric CO2 reductions accrue for all tree types. Average annual net 

reductions range from a high of 436 lbs ($1.46) for a large tree on the west side of a 

house to a low of 194 lbs ($0.65) for a small tree on the southern side of the house. 

Deciduous trees opposite west-facing house walls generally produce the greatest 

CO2 reduction because of reduced power plant emissions associated with energy 

savings. The values for the crabapple tree are lowest for CO2 reduction reflecting 

this small tree’s minor effect on energy savings and sequestration. 

Forty years after planting, net CO2 benefits for a yard tree opposite a west wall 

are 420, 543, 638, and 195 lbs for the small, medium, and large deciduous trees 

and the conifer, respectively. Releases of CO2 associated with tree care activities 

account for less than 1 percent of net CO2 sequestration.
36

GENERAL TECHNICAL REPORT PSW-GTR-206 

In the Temperate Interior West region, trees play an environmental, cultural, and historical role in communities.

Brian Jorgenson
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

37

Chapter 4. Estimating Benefits and Costs for Tree 

Planting Projects in Your Community

This chapter shows two ways that benefit-cost information presented in this guide 

can be used. The first hypothetical example demonstrates how to adjust values 

from the guide for local conditions when the goal is to estimate benefits and costs 

for a proposed tree planting project. The second example explains how to compare net benefits derived from planting different types of trees. The last section 

discusses actions communities can take to increase the cost-effectiveness of their 

tree programs.

Applying Benefit-Cost Data

Chinook Valley Example

The hypothetical city of Chinook Valley is located in the Temperate Interior West 

region and has a population of 24,000. Most of its street trees were planted decades 

ago, with English elms and silver maples (see “Common and Scientific Names” 

section) as the dominant species. Currently, the tree canopy cover is sparse because 

a number of trees died after drought conditions made them more susceptible to 

pests, and they have not been replaced. Many of the remaining street trees are in 

declining health. The city hired an urban forester 2 years ago and an active citizens’ 

group, the Green Team, has formed (fig. 20).

Figure 20—The (hypothetical) Green 

Team is motivated to re-green their 

community by planting 1,000 trees in 

5 years.
38

GENERAL TECHNICAL REPORT PSW-GTR-206 

Initial discussions among the Green Team, local utilities, the urban forester, 

and other partners led to a proposed urban forestry program. The program intends 

to plant 1,000 trees in Chinook Valley over a 5-year period. Trained volunteers will 

plant 3-in diameter trees in the following proportions: 70 percent large-maturing 

trees, 15 percent medium-maturing trees, 5 percent small-maturing trees, and 10 

percent conifers. One hundred trees will be planted in parks, and the remaining 

900 trees will be planted along Main Street and other downtown streets. Mortality 

rates for earlier planting projects have been high, so the Green Team and the urban 

forester will concentrate their planting efforts in areas that are likely to be most 

successful, including planting spaces with sufficient soil capacity for trees to grow 

and as little conflict with infrastructure as possible, and that maximize environmental benefits. They expect to find a number of good suggestions for planting in 

chapter 5 of this guide. 

The Chinook Valley City Council has agreed to maintain the current funding level for management of existing trees. Also, they will advocate formation 

of a municipal tree district to raise funds for the proposed tree-planting project. 

A municipal tree district is similar in concept to a landscape assessment district, 

which receives revenues based on formulas that account for the services different 

customers receive. For example, the proximity of customers to greenspace in a 

landscape assessment district may determine how much they pay for upkeep. A 

municipal tree district might receive funding from air quality districts, stormwater 

management agencies, electric utilities, businesses, and residents in proportion 

to the value of future benefits these groups will receive from trees in terms of air 

quality, hydrology, energy, carbon dioxide (CO2), and property value. The formation 

of such a district would require voter approval of a special assessment that charges 

recipients for tree planting and maintenance costs in proportion to the benefits 

they receive from the new trees. The council needs to know the amount of funding required for tree planting and maintenance, as well as how the benefits will be 

distributed over the 40-year life of the project.

As a first step, the Chinook Valley city forester and Green Team decided to 

use the tables in appendix 2 to quantify total cumulative benefits and costs over 40 

years for the proposed planting of 1,000 public trees—700 large, 150 medium, and 

50 small deciduous trees and 100 conifers.

Before setting up a spreadsheet to calculate benefits and costs, the team considered which aspects of Chinook Valley’s urban and community forestry project 

differ from the regional values used in this guide (the methods for calculating the 

values in app. 2 are described in app. 3): 

The first step: 

determine tree 

planting numbers
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

39

1. The prices of electricity and natural gas in Chinook Valley are $0.06 per kWh 

and $1.05 per therm, not $0.082 per kWh and $1.17 per therm as used in this 

guide. It is assumed that the buildings that will be shaded by the new street 

trees have air conditioning and natural-gas heating.

2. The Green Team projected future annual costs for monitoring tree health and 

implementing their stewardship program. Administration costs are estimated to 

average $2,500 annually for the life of the trees or $2.50 per tree each year. This 

guide assumed an average annual administration cost of about $3.00 per tree. 

Thus, an adjustment is necessary.

3. Planting will cost $200 per tree. The guide assumes planting costs of $140 per 

tree. The costs will be slightly higher for Chinook Valley because they have 

decided to plant larger trees. 

To calculate the dollar value of total benefits and costs for the 40-year period, 

the forester created a spreadsheet table (table 4). Each benefit and cost category 

is listed in the first column. Prices, adjusted where necessary for Chinook Valley, 

are entered into the second column. The third column contains the resource 

units (RUs) per tree per year associated with the benefit or the cost per tree per 

year, which can be found in appendix 2. For aesthetic and other benefits, the 

dollar values for public trees are placed in the RU columns. The fourth column 

lists the 40-year total values, obtained by multiplying the RU values by tree 

numbers, prices, and 40 years.

To adjust for higher electricity prices, the forester multiplied electricity 

saved for a large public tree in the RU column (209 kWh) by the Chinook 

Valley price for electricity ($0.06/kWh). This value ($12.54 per tree per year) 

was multiplied by the number of trees planted and 40 years ($12.54 × 700 trees 

× 40 years = $351,120) to obtain cumulative air-conditioning energy savings 

for the large public trees (table 4). The process was carried out for all benefits 

and all tree types.

To adjust cost figures, the city forester changed the planting cost from $140 

assumed in the guide to $200 (table 4). This planting cost was annualized by 

dividing the cost per tree by 40 years ($200/40 = $5.00 per tree per year). Total 

planting costs were calculated by multiplying this value by 700 large trees and 40 

years ($140,000).

The administration, inspection, and outreach costs are expected to average 

$2.50 per tree per year. Consequently, the total administration cost for large trees is 

$2.50 × 700 large trees × 40 years ($70,000). The same procedure was followed to 

calculate costs for the medium and small trees and conifers.

The second step: 

adjust for local prices 

of benefits

The third step: adjust 

for local costs
40

GENERAL TECHNICAL REPORT PSW-GTR-206 

Table 4—Spreadsheet calculations of benefits and costs for the Chinook Valley planting project (1,000 trees) over 40 years 50 small trees 150 medium trees 700 large trees 100 conifer trees 1,000 total trees Benefits Adjusted price Resource units Total value Resource units Total value Resource units Total value Resource units Total value Total value Percentage of benefits Dollars Resource units per tree per year Dollars Resource units per tree per year Dollars Resource units per tree per year Dollars Resource units per tree per year Dollars Resource units per tree per year Dollars Percent Electricity (kWh) 0.0600 100 12,000 160 57,600 209 351,120 67 16,080 10.92 436,800 20.2 Natural gas (therms) 1.05 6.91 14,511 9.62 60,606 11.17 328,398 7.05 29,610 10.83 433,125 20.0 Net carbon dioxide (lb) 0.00334 214 1,430 313 6,273 358 33,480 150 2,004 1.08 43,187 2.0 Ozone (lb) 0.51 0.20 204 0.31 949 0.70 9,996 0.22 449 0.29 11,598 2.0 Nitrogen dioxide (lb) 0.51 0.33 337 0.52 1,591 0.69 9,853 0.23 469 0.31 12,250 Sulfur dioxide (lb) 0.06 0.66 79 1.13 407 1.39 2,335 0.34 82 0.07 2,903 Small particulate matter (lb) 0.92 0.17 313 0.27 1,490 0.59 15,198 0.17 626 0.44 17,627 Volatile organic compounds (lb) 0.14 0.06 17 0.10 84 0.12 470 0.03 17 0.01 588 Biogenic volatile organic compounds (lb) 0.14 0 0 -0.16 -134 0 0 -1.94 -1,086 -0.03 -1,220 Hydrology (gal) 0.0050 161 1,610 893 26,790 1,111 155,540 1,459 29,180 5.33 213,120 9.9 Aesthetics and other 9.76 19,520 17.87 107,220 29.32 820,960 11.54 46,160 24.85 993,860 45.9 Total benefits 50,003 262,800 1,726,949 123,567 54.09 2,163,319 100.0 Costs Per tree Total value Per tree Total value Per tree Total value Per tree Total value Per tree Total value Percentage of costs Dollars per tree per year Dollars Dollars per tree per year Dollars Dollars per tree per year Dollars Dollars per tree per year Dollars Dollars per tree per year Dollars Percent Tree and planting 5.00 10,000 5.00 30,000 5.00 140,000 5.00 20,000 5.00 200,000 27.0 Pruning 5.42 10,840 6.52 39,120 6.97 195,160 0.50 2,019 6.18 247,162 33.5 Remove and dispose 2.22 4,440 2.72 16,320 2.77 77,560 2.51 10,040 2.71 108,360 14.7 Infrastructure repair 1.28 2,562 1.57 9,400 1.60 44,773 1.45 5,786 1.56 62,520 8.5 Irrigation 0.37 740 0.46 2,760 0.47 13,160 0.42 1,680 0.46 18,340 2.5 Cleanup 0.04 80 0.05 300 0.05 1,400 0.05 200 0.05 1,980 0.3 Admin. and other 2.50 5,000 2.50 15,000 2.50 70,000 2.50 10,000 2.50 100,000 13.6 Total costs 33,673 112,905 542,080 49,707 18.46 738,269 100.0 Net benefit 16,343 149,880 1,184,869 73,847 35.64 1,424,939 Benefit/cost ratio 1.49 2.33 3.19 2.49 2.93 RU = resource unit.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

41

All costs and all benefits were summed. Annual benefits over 40 years for the 

whole planting total $2.16 million ($54.10 per tree per year), and annual costs total 

about $740,000 ($18.46 per tree per year). Subtracting total costs from total benefits 

yields net benefits over the 40-year period:

• $16,343 or $8.17 per tree per year for small deciduous trees

• $149,880 or $24.98 per tree per year for medium deciduous trees

• $1,184,869 or $42.32 per tree per year for large deciduous trees

• $73,847 or $18.46 per tree per year for conifers

Dividing total benefits by total costs yielded benefit-cost ratios (BCRs) of 1.49 

for small trees, and 2.33, 3.19, and 2.49 for medium and large deciduous trees and 

conifers. The BCR for the entire planting is 2.93, indicating that $2.93 will be 

returned for every $1 invested.

This analysis assumes 43 percent of the planted trees die and does not account 

for the time value of money from a capital investment perspective. Use the municipal discount rate to compare this investment in tree planting and management with 

alternative municipal investments.

The city forester and Green Team now know that the project will cost about 

$740,000, and the average annual cost will be $18,500 ($740,000/40 years); 

however, a higher proportion of funds will be needed initially for planting and 

irrigation. The fifth and last step is to identify the distribution of functional benefits 

that the trees will provide. The last column in table 4 shows the distribution of 

benefits as a percentage of the total:

• Energy savings = 40 percent (cooling = 20 percent, heating = 20 percent)

• CO2 reduction = 2 percent

• Stormwater runoff reduction = 10 percent

• Air quality improvement = 2 percent

• Aesthetics/property value increase = 46 percent

With this information the planning team can determine how to distribute the 

costs for tree planting and maintenance based on who benefits from the services 

the trees will provide. For example, assuming the goal is to generate enough annual 

revenue to cover the total costs of managing the trees ($740,000), fees could be 

distributed in the following manner:

• $296,000 from electric and natural gas utilities for peak energy savings (40 

percent). (Utility companies invest in planting trees because it is more cost 

effective to reduce peak energy demand than to meet peak needs through added 

infrastructure.)

The fourth step: 

calculate net benefits 

and benefit-cost ratio 

for public trees

The final step: 

determine how 

benefits are 

distributed and link 

these to sources of 

revenue

Distributing costs of 

tree management to 

multiple parties
42

GENERAL TECHNICAL REPORT PSW-GTR-206 

• $15,000 from local industry for atmospheric CO2 reductions (2 percent).

• $74,000 from the stormwater management district for water quality improvement associated with reduced runoff (10 percent).

• $15,000 from air quality management district for net reduction in air pollutants 

(2 percent).

• $340,000 from property owners for increased property values (46 percent).

Whether funds are sought from partners, the general fund, or other sources, 

this information can assist managers in developing policy, setting priorities, and 

making decisions. The Center for Urban Forest Research has developed a computer 

program called STRATUM that simplifies these calculations for analysis of existing street tree populations (Maco and McPherson 2003; for more information, see 

USDA FS 2006a). 

City of Solanum Example

As a municipal cost-cutting measure, the hypothetical city of Solanum plans to 

stop planting street trees in areas of new development. Instead, developers will be 

required to plant front yard trees, thereby reducing costs to the city. The community forester and concerned citizens believe that, although this policy will result in 

lower planting costs, developers may plant smaller trees than the city would have. 

Currently, Solanum’s policy is to plant as large a tree as possible based on each 

site’s available growing space (fig. 21). Planting smaller trees could result in benefits 

“forgone” that will exceed cost savings. To evaluate this possible outcome, the 

community forester and concerned citizens decided to compare costs and benefits 

of planting small, medium, and large trees for a hypothetical street-tree planting 

project in Solanum.

As a first step, the city forester and concerned citizens decided to quantify the 

total cumulative benefits and costs over 40 years for a typical street tree planting of 

1,500 trees in Solanum. For comparison purposes, the planting includes 500 small 

trees, 500 medium trees, and 500 large trees. Data in appendix 2 are used for the 

calculations; however, three aspects of Solanum’s urban and community forestry 

program are different from those assumed in this tree guide: 

1. The price of electricity is $0.075/kWh, not $0.082/kWh. 

2. The city will provide irrigation for the first 5 years at a cost of approximately 

$0.50 per tree annually.

3. Planting costs are $225 per tree for city trees instead of $140 per tree.

To calculate the dollar value of total benefits and costs for the 40-year period, 

the last column in the appendix 2 tables (40-year average) is multiplied by 40 years. 

The first step: 

calculate benefits 

and costs over 40 

years
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

43

Because this value is for one tree it must be multiplied by the total number of trees 

planted in the respective small, medium, or large tree size classes. To adjust for 

higher electricity prices, we multiply electricity saved per tree in the RU column 

(tables 6, 9, 12, and 15) for each tree type by the number of trees and 40 years (large 

tree: 209 kWh × 500 trees × 40 years = 4,180,000 kWh). This value is multiplied 

by the price of electricity in Solanum ($0.075/kWh × 4,180,000 kWh = $313,500) to 

obtain cumulative air-conditioning energy savings for the project (table 5).

All the benefits are summed for each size tree for a 40-year period. The 500 

small trees provide $530,400 in total benefits. The medium and large trees provide 

approximately $924,200 and $1.3 million, respectively.

To adjust cost figures, we add a value for irrigation by multiplying the annual 

cost by the number of trees and by the number of years that irrigation will be 

applied ($0.50 × 500 trees × 5 years = $1,250). We multiply 500 large trees by the 

unit planting cost ($225) to obtain the adjusted cost for planting (500 × $225 = 

$100,000). The average annual 40-year costs taken from appendix 2 for other items 

are multiplied by 40 years and the appropriate number of trees to compute total 

Figure 21— A policy such as 

Solanum’s, to plant as large a 

tree as the site will handle, has 

provided ample benefits in the 

past. Here, large-growing trees 

are being planted. Brian Jorgenson

The second step: 

adjust for local prices 

of benefits

The third step: adjust 

for local costs
44

GENERAL TECHNICAL REPORT PSW-GTR-206 

costs. These 40-year cost values are entered into table 5. The total costs for the 

small, medium and large trees are $338,050, $389,050, and $401,250.

Subtracting total costs from total benefits yields net benefits for the small 

($192,350), medium ($535,150), and large ($895,500) trees. The total net benefits for 

the 40-year period are $1.6 million (total benefits - total costs), or $1,082 per tree on 

average (table 5).

The net benefits per public tree over the 40-year period are as follows:

• $385 for a small tree

• $1,070 for a medium tree

• $1,791 for a large tree

Table 5—Spreadsheet calculations of benefits and costs for the Solanum planting project (1,500 trees) over 40 years 

500 small 500 medium 500 large 1,500 tree total

Benefits RUs

Total 

value RUs

Total 

value RUs

Total 

value RUs

Total 

value

Average

value per 

tree

Dollars Dollars Dollars Dollars Dollars

Electricity (kWh) 2,000,000 150,000 3,200,000 240,000 4,180,000 313,500 9,380,000 703,600 469

Natural gas (therms) 138,200 145,200 192,400 202,000 223,400 234,600 554,000 581,800 388

Net carbon dioxide (lb) 4,280,000 14,200 6,260,000 20,800 7,160,000 24,000 17,700,000 59,000 39

Ozone (lb) 4,030 2,000 6,270 3,200 13,930 7,200 24,230 12,400 8

Nitrogen dioxide (lb) 6,610 3,400 10,440 5,400 13,790 7,000 30,840 15,800 11

Sulfur dioxide (lb) 13,240 800 22,670 1,400 27,890 1,600 63,800 3,800 3

Small particulate 

matter (lb) 3,450 3,200 5,400 5,000 11,800 10,800 20,650 19,000 13

Volatile organic 

compounds (lb) 1,180 200 1,980 200 2,440 400 5,600 800 1

Biogenic volatile organic 

compunds (lb) -70 0 -3,290 -400 0 0 -3,360 -400 0

Hydrology (gal) 3,220,000 16,200 17,860,000 89,200 22,220,000 111,200 43,300,000 216,600 144

Aesthetics and other 

benefits 195,200 357,400 586,400 1,139,000 759

Total benefits 530,400 924,200 1,296,700 2,751,400 1,834

Costs 

Total 

value

Total 

value

Total 

value

Total 

value

Average

value per 

tree

Dollars Dollars Dollars Dollars Dollars

Tree and planting 100,000 100,000 100,000 300,000 200

Pruning 108,400 130,400 139,400 378,200 252

Remove and dispose 44,400 54,400 55,400 154,200 103

Infrastructure 25,600 31,400 32,000 89,000 59

Irrigation 1,250 1,250 1,250 3,750 3

Cleanup 7,400 9,200 9,400 26,000 17

Liability and legal 800 1,000 1,000 2,800 2

Admin. and other 50,200 61,400 62,800 174,400 116

Total costs 338,050 389,050 401,250 1,128,350 752

Net benefits 192,350 535,150 895,500 1,623,050 1,082

Benefit-cost ratio 1.57 2.38 3.23 2.44

RU = resource unit.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

45

By not investing in street tree planting, the city would save $300,000 in initial 

planting costs. If the developer planted 1,500 small trees, benefits would total 

$1.6 million (3 × $530,400 for 500 small trees). If 1,500 large trees were planted, 

benefits would total $3.9 million. Planting all small trees causes the city to forgo 

benefits valued at $2.3 million. This amount far exceeds the savings of $300,000 

obtained by requiring developers to plant new street trees, and suggests that, when 

turning over the responsibility for tree planting to others, the city would benefit by 

developing and enforcing a street tree ordinance that requires planting large trees 

where feasible. 

Based on this analysis, the City of Solanum decided to retain the policy of 

promoting planting of large trees where space permits and require tree shade plans 

that show how developers will achieve 50 percent shade over streets, sidewalks, and 

parking lots within 15 years of development.

This analysis assumes that 43 percent of the planted trees died. It does not 

account for the time value of money from a capital investment perspective, but this 

could be done by using the municipal discount rate.

Increasing Program Cost-Effectiveness

What if the program you have designed looks promising in terms of stormwaterrunoff reduction, energy savings, volunteer participation, and additional benefits, 

but the costs are too high? This section describes some steps to consider that may 

increase benefits and reduce costs, thereby increasing cost-effectiveness.

Increasing Benefits

Improved stewardship to increase the health and survival of recently planted trees 

is one strategy for increasing cost-effectiveness. An evaluation of the Sacramento 

Shade program found that tree survival rates had a substantial impact on projected 

benefits (Hildebrandt et al. 1996). Higher survival rates increase energy savings and 

reduce tree removal and planting costs.

Conifers and broadleaf evergreens intercept rainfall and particulate matter year 

round as well as reduce windspeeds and provide shade, which lowers summer cooling and winter heating costs. Locating these types of trees in yards, parks, school 

grounds, and other open-space areas can increase benefits.

Energy benefits can be further increased by planting a higher percentage of 

trees in locations that produce the greatest energy savings, such as opposite westfacing walls and close to buildings with air conditioning. Keep in mind that evergreen trees should not be planted on the southern side of buildings because their 

branches and leaves block the warm rays of the winter sun. By customizing tree 

locations to increase numbers in high-yield sites, energy savings can be boosted.

The fourth step: 

calculate cost saving 

and benefits forgone

What if costs are too 

high?

Work to increase 

survival rates

Target tree plantings 

with highest return

Customize planting 

locations
46

GENERAL TECHNICAL REPORT PSW-GTR-206 

Reducing Program Costs

Cost effectiveness is influenced by program costs as well as benefits:

Cost effectiveness = total benefit/total program cost

Cutting costs is one strategy to increase cost effectiveness. A substantial 

percentage of total program cost occurs during the first 5 years and is associated with tree planting and establishment (McPherson 1993). Some strategies to 

reduce these costs include:

• Plant bare-root or smaller tree stock.

• Use trained volunteers for planting and pruning of young trees (fig. 22).

• Provide followup care to increase tree survival and reduce replacement 

costs.

• Select and locate trees to avoid conflicts with infrastructure.

Where growing conditions are likely to be favorable, such as yard or garden 

settings, it may be cost effective to use smaller, less expensive stock or bare-root 

trees. In highly urbanized settings and sites subject to vandalism, however, large 

stock may survive the initial establishment period better than small stock.

Figure 22—Trained volunteers 

can plant and maintain young 

trees, allowing the community 

to accomplish more at less 

cost and providing satisfaction 

for participants. Tree Trust

Reduce up-front and 

establishment costs

Use less expensive 

stock where 

appropriate
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

47

Although organizing and training volunteers requires labor and resources, it 

is usually less costly than contracting the work, and it can help build more support 

for your program. A cadre of trained volunteers can easily maintain trees until they 

reach a height of about 20 ft and limbs are too high to prune from the ground with 

pole pruners. By the time trees reach this size they are well established. Pruning 

during this establishment period should result in trees that will require less care in 

the long term. Training young trees can provide a strong branching structure that 

requires less frequent thinning and shaping (Costello 2000). Ideally, young trees 

should be inspected and pruned every other year for the first 5 years after planting.

As trees grow larger, pruning costs may increase on a per-tree basis. The 

frequency of pruning will influence these costs, as it takes longer to prune a tree 

that has not been pruned in 10 years than one that was pruned a few years ago. 

Although pruning frequency differs by species and location, a return frequency of 

about 5 to 8 years is usually sufficient for older trees (Miller 1997).

Investing in the resources needed to promote tree establishment during the first 

5 years after planting is usually worthwhile, because once trees are established they 

have a high probability of continued survival. If your program has targeted trees on 

private property, then encourage residents to attend tree-care workshops. Develop 

standards of “establishment success” for different types of tree species. Perform 

periodic inspections to alert residents to tree health problems, and reward those 

whose trees meet your program’s establishment standards. Replace dead trees as 

soon as possible, and identify ways to improve survivability.

Carefully select and locate trees to avoid conflicts with overhead power 

lines, sidewalks, and underground utilities. Time spent planning the planting 

will result in long-term savings. Also consider soil type and irrigation, microclimate, and the type of activities occurring around the tree that will influence its 

growth and management.

When evaluating the bottom line—trees pay us back—do not forget to consider 

benefits other than the stormwater-runoff reductions, energy savings, atmospheric 

CO2 reductions, and other tangible benefits. The magnitude of benefits related to 

employment opportunities, job training, community building, reduced violence, 

and enhanced human health and well-being can be substantial (fig. 23). Moreover, 

these benefits extend beyond the site where trees are planted, furthering collaborative efforts to build better communities.

For more information on urban and community forestry program design and 

implementation, see the list of additional resources in appendix 1.

Match tree to site

It all adds up—trees 

pay us back

Prune early
48

GENERAL TECHNICAL REPORT PSW-GTR-206 

Figure 23—Trees pay us back in tangible and intangible ways.

Brian Jorgenson
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

49

Chapter 5. General Guidelines for Selecting and 

Placing Trees

Guidelines for Energy Savings

Maximizing Energy Savings From Shading

The right tree in the right place can save energy and reduce tree care costs. In 

midsummer, the sun shines on the east side of a building in the morning, passes 

over the roof near midday, and then shines on the west side in the afternoon 

(see fig. 4). Electricity use is highest during the afternoon when temperatures 

are warmest and incoming sunshine is greatest. Therefore, the west side of a home 

is the most important side to shade (Sand 1993) (fig. 24).

Depending on building orientation and window placement, sun shining through 

windows can heat a home quickly during the morning hours. The east side is the 

second most important side to shade when considering the net impact of tree shade 

on energy savings (fig. 24). Deciduous trees on the east side provide summer shade 

and more winter solar heat gain than evergreens.

Trees located to shade south walls can block winter sunshine and increase 

heating costs because during winter the sun is lower in the sky and shines on 

the south side of homes (fig. 25). The warmth the sun provides is an asset, and 

planting evergreen trees on the southern side of a home would block southern 

exposures and solar collectors. Use solar-friendly trees to the south because the 

bare branches of these deciduous trees allow most sunlight to strike the building 

(some solar-unfriendly deciduous trees can reduce sunlight striking the south 

side of buildings by 50 percent even without leaves) (Ames 1987). Examples of 

solar-friendly trees include most species and cultivars of maples, crapemyrtle, 

Figure 24—Locate trees to shade west and east windows (from Sand 

1993).

Figure 25—Select solar-friendly trees for southern exposures 

and locate them close enough to provide winter solar access 

and summer shade (from Sand 1991).

Where should shade 

trees be planted?
50

GENERAL TECHNICAL REPORT PSW-GTR-206 

honeylocust, sweetgum, and zelkova (see “Common and Scientific Names” 

section). Some solar-unfriendly trees include most oaks, sycamore, most elms, 

and river birch (McPherson et al. 1994).

To maximize summer shade and minimize winter shade, locate shade trees about 

10 to 20 ft south of the home. As trees grow taller, prune lower branches to allow 

more sun to reach the building if this will not weaken the tree’s structure (fig. 26).

Although the closer a tree is to a home the more shade it provides, roots of trees 

that are too close can damage the foundation. Branches too close to the building can 

make it difficult to maintain exterior walls and windows. Keep trees 10 ft or farther 

from the home depending on mature crown spread, to avoid these conflicts. Trees 

within 30 to 50 ft of the home most effectively shade windows and walls.

Paved patios and driveways can become heat sinks that warm the home during 

the day. Shade trees can make them cooler and more comfortable spaces. If a home 

Figure 26—Trees south of a home before and after pruning. 

Lower branches are pruned up to increase heat gain from 

winter sun (from Sand 1993).
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

51

is equipped with an air conditioner, shading can reduce its energy use, but do not 

plant vegetation so close that it will obstruct the flow of air around the unit.

Plant only small-growing trees under overhead power lines, and avoid planting 

directly above underground water and sewer lines if possible. Contact your local 

utility company before planting to determine where underground lines are located 

and which tree species should not be planted below power lines.

Planting Windbreaks for Heating Savings

A tree’s size and crown density can make it ideal for blocking wind, thereby reducing the impacts of cold winter weather. Locate rows of trees perpendicular to the 

prevailing wind (fig. 27), usually the north and west side of homes in the Temperate 

Interior West region.

Design the windbreak row to be longer than the building being sheltered 

because windspeed increases at the edge of the windbreak. Ideally, the windbreak 

should be planted upwind about 25 to 50 ft from the building and should consist 

of dense evergreens that will grow to twice the height of the building they shelter 

(Heisler 1986, Sand 1991). Avoid planting windbreaks that will block sunlight to 

south and east walls (fig. 28). Trees should be spaced close enough to form a dense 

screen, but not so close that they will block sunlight to each other, causing lower 

branches to self-prune. Most conifers can be spaced about 6 ft on center. If there is 

room for two or more rows, then space rows 10 to 12 ft apart.

Evergreens are preferred over deciduous trees for windbreaks because they 

provide better wind protection. The ideal windbreak tree is fast growing, visually 

dense, has strong branch attachments, and has stiff branches that do not self-prune. 

Figure 27—Evergreens protect a building from dust and cold by 

reducing windspeeds (from Sand 1993).

Figure 28—Midwinter shadows from a well-located windbreak and 

shade trees do not block solar radiation on the south-facing wall 

(from Sand 1993).

Plant dense 

evergreens
52

GENERAL TECHNICAL REPORT PSW-GTR-206 

Your local cooperative extension agent or urban forester can help you select appropriate trees for your area.

In settings where vegetation is not a fire hazard, evergreens planted close to 

the home create airspaces that reduce air infiltration and heat loss. Allow shrubs to 

form thick hedges, especially along north, west, and east walls.

Selecting Trees to Maximize Benefits

The ideal shade tree has a fairly dense, round crown with limbs broad enough to 

partially shade the roof. Given the same placement, a large tree will provide 

more shade than a small tree. Deciduous trees allow sun to shine through leafless branches in winter. Plant small trees where nearby buildings or power lines 

limit aboveground space. Columnar trees are appropriate in narrow side yards. 

Because the best location for shade trees is relatively close to the west and east 

sides of buildings, the most suitable trees will be strong and capable of resisting 

storm damage, disease, and pests (Sand 1994). Examples of trees not to select for 

placement near buildings include cottonwoods and silver maple because of their 

invasive roots, weak wood, and large size, and ginkgos because of their sparse 

shade and slow growth.

When selecting trees, match the tree’s water requirements with those of surrounding plants. For instance, select low-water-use species for planting in areas 

that receive little irrigation. Also, match the tree’s maintenance requirements with 

the amount of care and the type of use different areas in the landscape receive. For 

instance, tree species that drop fruit that can be a slip-and-fall problem should not 

be planted near paved areas that are frequently used by pedestrians. Check with 

your local landscape professional before selecting trees to make sure that they are 

well suited to the site’s soil and climatic conditions.

Use the following practices to plant and manage trees strategically to maximize 

energy conservation benefits:

• Increase community-wide tree canopy, and target shade to streets, parking lots, 

and other paved surfaces, as well as air-conditioned buildings.

• Shade west- and east-facing windows and walls.

• Avoid planting trees to the south of buildings.

• Select solar-friendly trees opposite east- and south-facing walls.

• Shade air conditioners, but don’t obstruct airflow.

• Avoid planting trees too close to utilities and buildings.

• Create multirow, evergreen windbreaks where space permits that are longer 

than the building.

Picking the right tree

Maximizing energy 

savings from trees
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

53

Guidelines for Reducing Carbon Dioxide

Because trees in common areas and other public places may not shelter buildings 

from sun and wind and reduce energy use, carbon dioxide (CO2) reductions are 

primarily due to sequestration. Fast-growing trees sequester more CO2 initially 

than slow-growing trees, but this advantage can be lost if the fast-growing trees 

die at younger ages. Large trees have the capacity to store more CO2 than smaller 

trees (fig. 29). To maximize CO2 sequestration, select tree species that are well 

suited to the site where they will be planted. Consult with your local arborist to 

select the right tree for your site. Trees that are not well adapted will grow slowly, 

show symptoms of stress, or die at an early age. Unhealthy trees do little to reduce 

atmospheric CO2 and can be unsightly liabilities in the landscape.

Design and management guidelines that can increase CO2 reductions include 

the following:

• Maximize use of woody plants, especially trees, as they store more CO2 than do 

herbaceous plants and grasses.

• Plant more trees where feasible, and immediately replace dead trees to compensate for CO2 lost through removal.

• Create diverse habitats, with trees of different ages and species, to promote a 

continuous canopy cover over time.

Figure 29—Compared with small trees, large trees can store more carbon, filter more air pollutants, intercept more rainfall, and provide greater energy savings. Here young white ash trees line a 

downtown Boise street.

 (photo courtesy of Brian Jorgenson)

Brian Jorgenson
54

GENERAL TECHNICAL REPORT PSW-GTR-206 

• Group species with similar landscape maintenance requirements together and 

consider how irrigation, pruning, fertilization, weed, pest, and disease control 

can be minimized.

• Reduce CO2 associated with landscape management by using push mowers (not 

gas or electric), hand saws (not chain saws), pruners (not gas/electric shears), 

rakes (not leaf blowers), and employ landscape professionals who don’t have to 

travel far to your site.

• Reduce maintenance by reducing turfgrass and planting drought-tolerant or 

environmentally friendly landscapes. 

• Consider the project’s lifespan when selecting species. Fast-growing species 

will sequester more CO2 initially than slow-growing species, but may not live 

as long.

• Provide ample space belowground for tree roots to grow so that they can maximize CO2 sequestration and tree longevity.

• When trees die or are removed, salvage as much wood as possible for use as 

furniture and other long-lasting products to delay decomposition.

• Plant trees, shrubs, and vines in strategic locations to maximize summer shade 

and reduce winter shade, thereby reducing atmospheric CO2 emissions associated with power production.

Guidelines for Reducing Stormwater Runoff

Trees are mini-reservoirs, controlling runoff at the source because their leaves and 

branch surfaces intercept and store rainfall, thereby reducing runoff volumes and 

erosion of water-courses, as well as delaying the onset of peak flows. Rainfall interception by large trees is a relatively inexpensive first line of defense in the battle to 

control nonpoint-source pollution.

When selecting trees to maximize rainfall interception benefits, consider the 

following:

• Select tree species with physiological features that maximize interception, such 

as evergreen foliage, large leaf surface area, and rough surfaces that store water 

(Metro 2002).

• Increase interception by planting large trees where possible (fig. 30).

• Plant trees that are in leaf when precipitation levels are highest.

• Plant low-water-use tree species where appropriate and native species that, once 

established, require little supplemental irrigation.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

55

• In bioretention areas, such as roadside swales, select species that tolerate inundation, are long-lived, wide-spreading, and fast-growing (Metro 2002).

• Do not pave over streetside planting strips for easier weed control; this can 

reduce tree health and increase runoff.

• Bioswales in parking lots and other paved areas store and filter stormwater 

while providing good conditions for trees.

Guidelines for Improving Air Quality Benefits

Trees, sometimes called the “lungs of our cities,” are important because of their 

ability to remove contaminants from the air. The amount of gaseous pollutants and 

particulates removed by trees depends on their size and architecture, as well as 

local meteorology and pollutant concentrations.

Along streets, in parking lots, and in commercial areas, locate trees to maximize shade on paving and parked vehicles. Shade trees reduce heat that is stored 

or reflected by paved surfaces. By cooling streets and parking areas, trees reduce 

Figure 30—Trees can create a continuous canopy for maximum rainfall interception, even in 

commercial areas. In this example, a swale in the median filters runoff and provides ample space for 

large trees. Parking-space-sized planters contain the soil volume required to grow healthy, large trees 

(from Metro 2002).
56

GENERAL TECHNICAL REPORT PSW-GTR-206 

emissions of evaporative hydrocarbons from parked cars and thereby reduce smog 

formation (Scott et al. 1999). Large trees can shade a greater area than smaller trees, 

but should be used only where space permits. Remember that a tree needs space for 

both branches and roots. Keep in mind also that the soil along streets and parking 

lots will likely be compacted, and measures to reduce this problem, such as the use 

of engineered or structural soils, must be taken.

Tree planting and management guidelines to improve air quality include the following (Nowak 2000, Smith and Dochinger 1976):

• Select species that tolerate pollutants that are present in harmful concentrations. For example, in areas with high ozone (O3) concentration avoid sensitive 

species such as white and green ash, tulip poplar, and Austrian pine (Noble et 

al. 1988).

• Conifers have high surface-to-volume ratios and retain their foliage yearround, which may make them more effective than deciduous species. In parking areas, however, species should be carefully chosen to avoid those that give 

off sticky residues. 

• Species with long leaf stems (e.g., ash, maple) and hairy plant parts (e.g., oak, 

birch, sumac) are especially efficient interceptors.

• Effective uptake depends on proximity to the pollutant source and the amount 

of biomass. Where space and fire conditions permit, plant multilayered stands 

near the source of pollutants.

• In areas with unhealthy O3 concentrations, maximize use of plants that emit low 

levels of biogenic volatile organic compounds to reduce O3 formation.

• Sustain large, healthy trees; they produce the most benefits.

• To reduce emissions of volatile organic compounds and other pollutants, plant 

trees to shade parked cars and conserve energy.

Guidelines for Avoiding Conflicts With Infrastructure

Trees can become liabilities when they conflict with power lines, underground 

utilities, and other infrastructure elements. Guidelines to reduce conflicts with 

infrastructure include the following:

• Before planting, contact your local before-digging company, such as Call 

Before You Dig, Utility Notification Center, or One Call, to locate underground 

water, sewer, gas, and telecommunications lines.

• Avoid locating trees where they will block streetlights or views of traffic and 

commercial signs.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

57

• Check with local transportation officials for sight visibility requirements. Keep 

trees at least 30 ft away from street intersections to ensure visibility.

• Avoid planting shallow-rooting species near sidewalks, curbs, and paving where 

tree roots can heave pavement if planted too close. Generally, avoid planting 

within 3 ft of pavement, and remember that trunk flare at the base of large 

trees can displace soil and paving for a considerable distance. Consider strategies to reduce damage by tree roots such as meandering sidewalks around trees 

(Costello and Jones 2003).

• Plant only small trees (<25 ft tall) under overhead power lines, and do not plant 

directly above underground water and sewer lines (fig. 31). Avoid locating trees 

where they will block illumination from streetlights or views of street signs in 

parking lots, commercial areas, and along streets.

Maintenance requirements and public safety concerns influence the type of 

trees selected for public places. The ideal public tree is not susceptible to wind 

Figure 31—Know where power lines and other utility lines are before planting. Under power lines, use 

only small-growing trees (“low zone”) and avoid planting directly above underground utilities. Larger 

trees may be planted where space permits (“medium” and “tall zones”) (from ISA 1992).
58

GENERAL TECHNICAL REPORT PSW-GTR-206 

damage and branch drop, does not require frequent pruning, produces negligible litter, is deep-rooted, has few serious pest and disease problems, and tolerates a wide 

range of soil conditions, irrigation regimes, and air pollutants. Because relatively 

few trees have all these traits, it is important to match the tree species to the planting site by determining what issues are most important on a case-by-case basis. For 

example, parking-lot trees should be tolerant of hot, dry conditions, have strong 

branch attachments, and be resistant to attacks by pests that leave vehicles covered 

with sticky exudates. Check with your local landscape professional for horticultural 

information on tree traits.

Guidelines for Maximizing Long-Term Benefits

Selecting a tree from the nursery that has a high probability of becoming a healthy, 

trouble-free mature tree is critical to a successful outcome. Therefore, select the 

very best stock at your nursery and, when necessary, reject nursery stock that does 

not meet industry standards.

The health of the tree’s root ball is critical to its ultimate survival. If the tree is 

in a container, check for matted roots by sliding off the container. Roots should penetrate to the edge of the root ball, but not densely circle the inside of the container 

or grow through drain holes. As well, at least two large structural roots should 

emerge from the trunk within 1 to 3 in of the soil surface. If there are no roots in 

the upper portion of the root ball, it is undersized and the tree should not be planted.

Another way to evaluate the quality of the tree before planting is to gently move 

the trunk back and forth. A good tree trunk bends and does not move in the soil, 

whereas a poor trunk bends a little and pivots at or below the soil line—a tell-tale 

sign of a poorly anchored tree.

Dig the planting hole 1 in shallower than the depth of the root ball to allow for 

some settling after watering. Make the hole two to three times as wide as the root 

ball and loosen the sides of the hole to make it easier for roots to penetrate. Place 

the tree so that the root flare is at the top of the soil. If the structural roots have 

grown properly as described above, the top of the root ball will be slightly higher 

(1 to 2 in) than the surrounding soil to allow for settling. Backfill with the native 

soil unless it is very rocky or sandy, in which case you may want to add composted 

organic matter such as peat moss or shredded bark (fig. 32).

Planting trees in urban plazas, commercial areas, and parking lots poses special 

challenges because of limited soil volume and poor soil structure. For trees to 

deliver benefits over the long term they require enough soil volume to grow and 

remain healthy. Matching tree species to the site’s soil volume can reduce sidewalk 

and curb damage as well. Figure 33 shows recommended soil volumes for different 

Planting trees 

correctly
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

59

sized trees. Engineered or structural soils can be placed under the hardscape to 

increase rooting space while meeting engineering requirements. For more information on structural soils see Reducing Infrastructure Damage by Tree Roots: A 

Compendium of Strategies (Costello and Jones 2003). 

Use the extra soil left after planting to build a berm outside the root ball that is 

6 in high and 3 ft in diameter. Soak the tree, and gently rock it to settle it in. Cover 

the basin with a 2- to 4-in layer of mulch, but avoid placing mulch against the tree 

trunk. Water the new tree two to three times a week and increase the amount of 

water as the tree grows larger. Generally, a tree requires about 1 in of water per 

week, although in areas of the Temperate Interior West trees may require as much 

as 2 in per week at the height of summer (Post 2007). A rain gauge or soil moisture 

sensor (tensiometer) can help determine tree watering needs, or contact your local 

cooperative extension agent or water conservancy district for recommendations.

After you’ve planted your tree, remember the following:

• Inspect your tree several times a year, and contact a local landscape professional if problems develop. 

• If your tree needed staking to keep it upright, remove the stake and ties after 

Figure 32— Prepare a broad planting area, plant the tree with the root flare at or just above ground 

level, and provide a berm/water ring to retain water (drawing courtesy of International Society of 

Arboriculture). (Note that trunk flare shown here represents a tree grown under optimum conditions. 

In trees grown under poorer conditions, the trunk flare may be hidden beneath the soil. These trees 

should be rejected in favor of those grown more carefully, or at the very least, the soil should be 

removed to expose the flare.)
60

GENERAL TECHNICAL REPORT PSW-GTR-206 

1 year or as soon as the tree can hold itself up. The staking should allow some 

tree movement, as this movement sends hormones to the roots causing them to 

grow and create greater tree stability. It also promotes trunk taper and growth. 

• Reapply mulch and irrigate the tree as needed. 

• Leave lower side branches on young trees for the first year and prune back to 4 

to 6 in to accelerate tree diameter development. Remove these lateral branches 

after the first full year. Prune the young tree to maintain a central main trunk 

and equally spaced branches. For more information, see Costello (2000) and 

Gilman (2002). As the tree matures, have it pruned on a regular basis by a certified arborist or other experienced professional. 

• By keeping your tree healthy, you maximize its ability to produce shade, intercept rainfall, reduce atmospheric CO2, and provide other benefits. 

For more information on tree selection, planting, establishment, and care see 

the resources listed in appendix 1.

Figure 33—Developed from several sources by Urban (1992), this graph shows the relationship 

between tree size and required soil volume. For example, a tree with a 16-inch diameter at breast 

height (41 cm) with 640 ft2 of crown projection area (59.5 m2 under the dripline) requires 1,000 ft3

(28 m3) of soil (from Costello and Jones 2003)
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

61

Glossary of Terms

annual fuel utilization efficiency (AFUE)—A measure of space heating 

equipment efficiency defined as the fraction of energy output per energy input.

anthropogenic—Produced by humans.

biodiversity—The variety of life forms in a given area. Diversity can be 

categorized in terms of the number of species, the variety in the area’s plant 

and animal communities, the genetic variability of the animals or plants, or a 

combination of these elements.

biogenic—Produced by living organisms.

biogenic volatile organic compounds (BVOCs)—Hydrocarbon compounds 

from vegetation (e.g., isoprene, monoterpene) that exist in the ambient air and 

contribute to the formation of smog or may themselves be toxic. Emission rates 

(μg·g-1·hr-1) used for this report follow Benjamin and Winer (1998):

• Fraxinus americana—0.0 (isoprene); 0.0 (monoterpene)

• Acer platanoides—0.0 (isoprene); 2.8 (monoterpene)

• Malus spp.—0.0 (isoprene); 0.1 (monoterpene)

• Picea pungens—4.0 (isoprene); 1.1 (monoterpene)

canopy—A layer or multiple layers of branches and foliage at the top or crown of a 

forest’s trees.

canopy cover—The area of land surface that is covered by tree canopy, as seen 

from above. 

Ccf—One hundred cubic feet.

climate—The average weather for a particular region and period (usually 30 

years). Weather describes the short-term state of the atmosphere; climate is the 

average pattern of weather for a particular region. Climatic elements include 

precipitation, temperature, humidity, sunshine, wind velocity, phenomena such 

as fog, frost, and hailstorms, and other measures of weather.

climate effects—Impact on residential space heating and cooling (kg of CO2

per tree per year) from trees located more than 50 ft from a building owing to 

associated reductions in windspeeds and summer air temperatures. 

community forests—The sum of all woody and associated vegetation in 

and around human settlements, ranging from small rural villages to 

metropolitan regions.
62

GENERAL TECHNICAL REPORT PSW-GTR-206 

contract rate—The percentage of residential trees cared for by commercial 

arborists; the proportion of trees for which a specific service (e.g., pruning or 

pest management) is contracted.

control costs—The marginal cost of preventing, controlling, or mitigating an impact.

crown—The branches and foliage at the top of a tree.

cultivar (derived from “cultivated variety”)—Denotes certain cultivated plants 

that are clearly distinguishable from others by any characteristic, and that when 

reproduced (sexually or asexually), retain their distinguishing characteristics. In 

the United States, “variety” is often considered synonymous with “cultivar.”

damage costs—The total estimated economic loss produced by an impact.

deciduous—Trees or shrubs that lose their leaves every fall.

diameter at breast height (d.b.h.)—The diameter of a tree outside the bark 

measured 4.5 ft above the ground on the uphill side (where applicable) of the tree.

dripline—The area beneath a tree marked by the outer edges of the branches.

emission factor—The rate of CO2, nitrogen dioxide (NO2), sulfur dioxide (SO2), 

and small particulate matter (PM10) output resulting from the consumption of 

electricity, natural gas, or any other fuel source.

evapotranspiration (ET)—The total loss of water by evaporation from the soil 

surface and by transpiration from plants, from a given area, and during a 

specified period.

evergreens—Trees or shrubs that are never entirely leafless. Evergreens may be 

broadleaved or coniferous (cone-bearing with needlelike leaves).

greenspace—Urban trees, forests, and associated vegetation in and around 

human settlements, ranging from small communities in rural settings to 

metropolitan regions.

hardscape—Paving and other impervious ground surfaces that reduce infiltration 

of water into the soil.

heat sinks—Paving, buildings, and other surfaces that store heat energy from 

the sun.

hourly pollutant dry deposition—Removal of gases from the atmosphere by 

direct transfer to natural surfaces and absorption of gases and particles by 

natural surfaces such as vegetation, soil, water, or snow.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

63

interception—Amount of rainfall held on tree leaves and stem surfaces.

kWh (kilowatt-hour)—A unit of work or energy, measured as 1 kW (1000 watts) 

of power expended for 1 hour.

leaf area index (LAI)—Total leaf area per unit area of crown if crown were 

projected in two dimensions.

leaf surface area (LSA)—Measurement of area of one side of a leaf or leaves.

mature tree—A tree that has reached a desired size or age for its intended use. 

Size, age, and economic maturity differ depending on the species, location, 

growing conditions, and intended use.

mature tree size—The approximate size of a tree 40 years after planting.

metric tonne—A measure of weight (abbreviated “t”) equal to 1 000 000 grams 

(1000 kilograms) or 2,205 pounds.

municipal forester—A person who manages public street or park trees (municipal 

forestry programs) for the benefit of the community.

MWh (megawatt-hour)—A unit of work or energy, measured as 1 megawatt 

(1 000 000 watts) of power expended for 1 hour. One MWh is equivalent to 

3.412 MBtu.

nitrogen oxides (oxides of nitrogen, NOx)—A general term for compounds of 

nitric acid (NO), nitrogen dioxide (NO2), and other oxides of nitrogen. Nitrogen 

oxides are typically created during combustion processes and are major 

contributors to smog formation and acid deposition. NO2 may cause numerous 

adverse human health effects.

ozone (O3)—A strong-smelling, pale blue, reactive toxic chemical gas with 

molecules of three oxygen atoms. It is a product of the photochemical process 

involving the Sun’s energy. Ozone exists in the upper layer of the atmosphere as 

well as at the Earth’s surface. Ozone at the Earth’s surface can cause numerous 

adverse human health effects. It is a major component of smog.

peak flow (or peak runoff)—The maximum rate of runoff at a given point or from 

a given area, during a specific period.

photosynthesis—The process in green plants of converting water and CO2 into 

sugar by using light energy; accompanied by the production of oxygen.

PM10 (particulate matter)—Major class of air pollutants consisting of tiny solid or 

liquid particles of soot, dust, smoke, fumes, and mists. The size of the particles 
64

GENERAL TECHNICAL REPORT PSW-GTR-206 

(10 microns or smaller, about 0.0004 in or less) allows them to enter the air sacs 

(gas-exchange region) deep in the lungs where they may be deposited and cause 

adverse health effects. PM10 also reduces visibility.

reduced power plant emissions—Reduced emissions of carbon dioxide (CO2) 

or other pollutants that result from reductions in building energy use owing to 

the moderating effect of trees on climate. Reduced energy use for heating and 

cooling results in reduced demand for electrical energy, which translates into 

fewer emissions by power plants.

resource unit (RU)—The value used to determine and calculate benefits and costs 

of individual trees. For example, the amount of air conditioning energy saved in 

kWh/year per tree, air-pollutant uptake in pounds per year per tree, or rainfall 

intercepted in gallons per tree per year.

riparian habitats—Narrow strips of land bordering creeks, rivers, lakes, or other 

bodies of water.

seasonal energy efficiency ratio (SEER)—Ratio of cooling output to power 

consumption; kBtu-output/kWh-input as a fraction. It is the Btu of cooling 

output during normal annual usage divided by the total electric energy input in 

kilowatt-hours during the same period.

sequestration—Annual net rate that a tree removes CO2 from the atmosphere 

through the processes of photosynthesis and respiration (kg of CO2 per tree 

per year).

shade coefficient—The percentage of light striking a tree crown that is transmitted 

through gaps in the crown. This is the percentage of light that hits the ground.

shade effects—Impact on residential space heating and cooling (kg of CO2 per tree 

per year) from trees located within 50 ft of a building.

solar-friendly trees—Trees that have characteristics that reduce blocking of winter 

sunlight. According to one numerical ranking system, these traits include open 

crowns during the winter heating season, leaves that fall early and appear late, 

relatively small size, and a slow growth rate (Ames 1987).

stem flow—Amount of rainfall that travels down the tree trunk and onto the ground.

sulfur dioxide (SO2)—A strong-smelling, colorless gas that is formed by the 

combustion of fossil fuels. Power plants, which may use coal or oil high in sulfur 

content, can be major sources of SO2. Sulfur oxides contribute to the problem of 

acid deposition.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

65

t—See metric tonne.

therm—A unit of heat equal to 100,000 British thermal units (BTUs) or 100 kBtu.

throughfall—Amount of rainfall that falls directly to the ground below the tree 

crown or drips onto the ground from branches and leaves.

transpiration—The loss of water vapor through the stomata of leaves.

tree or canopy cover—Within a specific area, the percentage covered by the crown 

of an individual tree or delimited by the vertical projection of its outermost 

perimeter; small openings in the crown are ignored. Used to express the relative 

importance of individual species within a vegetation community or to express 

the coverage of woody species.

tree litter—Fruit, leaves, twigs, and other debris shed by trees.

tree-related CO2 emissions—CO2 released when growing, planting, and caring for 

trees.

tree surface saturation storage capacity—The maximum volume of water that 

can be stored on a tree’s leaves, stems, and bark. This part of rainfall stored 

on the canopy surface does not contribute to surface runoff during and after a 

rainfall event.

urban heat island—An area in a city where summertime air temperatures are 3 

to 8 °F warmer than temperatures in the surrounding countryside. Urban areas 

are warmer for two reasons: (1) dark construction materials for roofs and asphalt 

absorb solar energy, and (2) few trees, shrubs, or other vegetation provide shade 

and cool the air.

volatile organic compounds (VOCs)—Hydrocarbon compounds that exist in the 

ambient air. VOCs contribute to the formation of smog or are themselves toxic. 

VOCs often have an odor. Some examples of VOCs are gasoline, alcohol, and the 

solvents used in paints.

willingness to pay—The maximum amount of money an individual would 

be willing to pay for nonmarket, public goods and services provided by 

environmental amenities such as trees and forests rather than do without.
66

GENERAL TECHNICAL REPORT PSW-GTR-206 

Common and Scientific Names

Common name Scientific name

Plants:

American linden Tilia americana L.

American sycamore Platanus occidentalis L.

Ash Fraxinus spp.

Austrian pine Pinus nigra J.F. Arnold

Birch Betula spp.

Blackgum Nyssa spp.

Black locust Robinia pseudoacacia L.

Black oak Quercus velutina Lam.

Black walnut Juglans nigra L.

Blue spruce Picea pungens Engelm.

Callery pear Pyrus calleryana Dcne.

Cottonwood Populus spp.

Crabapple Malus spp. 

Crapemyrtle Lagerstroemia indica L.

English elm Ulmus procera Salisb.

Elm Ulmus spp.

Ginkgo Ginkgo biloba L.

Green ash Fraxinus pennsylvanica Marshall

Hawthorn Crataegus spp.

Honeylocust Gleditsia triacanthos L.

London planetree Platanus hybrida Brot.

Maple Acer spp.

Northern catalpa Catalpa speciosa

Northern red oak Quercus rubra L.

Norway maple Acer platanoides L.

Oak Quercus spp.

Poplar Populus spp.

River birch Betula nigra L.

Russian olive Elaeagnus angustifolia L.

Scotch pine Pinus sylvestris L.

Siberian elm Ulmus pumila L.

Silver maple Acer saccharinum L.

Sugar maple Acer saccharum Marsh.

Sumac Rhus spp.

Sweetgum Liquidambar styraciflua L.

Sycamore Platanus spp.

Tree of heaven Ailanthus altissima (P. Mill.) Swingle

Tulip poplar Liriodendron tulipifera L.

White ash Fraxinus americana L.

Zelkova Zelkova serrata (Thunb.) Makino

Insects:

Emerald ash borer Agrilus planipennis Fairmaire
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

67

Metric Equivalents

When you know: Multiply by: To find:

Inches (in) 25,400 Microns

Inches (in) 25.4 Millimeters (mm)

Inches (in) 2.54 Centimeters (cm)

Feet (ft) .305 Meters (m)

Square feet (ft2) .0929 Square meters (m2)

Miles (mi) 1.61 Kilometers (km)

Square miles (mi2) 2.59 Square kilometers (km2)

Acre-feet 1233.6 Cubic meters (m3)

Gallons (gal) .00378 Cubic meters (m3)

Ounces 28.35 Grams (g)

Ounces 28,349,523 Micrograms (μg)

Pounds (lb) .454 Kilograms (kg)

Pounds per square foot (lb/ft2) 4.882 Kilograms per square meter (kg/m2)

Tons (ton) .907 Metric tonne (t)

Million BTUs .2931 Megawatt hours (MWh)

Therms 29.31 Kilowatt hours (kWh)

Fahrenheit (°F) .56 (F-32) Celsius (°C)

Acknowledgments

A number of people assisted with data collection and provided technical assistance: 

Brian Jorgenson, Jerry Stallsmith (Community Forestry, Boise, Idaho); Eric Wing 

(Information Technology Department, Boise, Idaho); Johanna Bell (Public Works 

Department, Boise, Idaho); Stephanie Huang, Christine Yang, and Aywon-Anh 

Nguyen (Center for Urban Forest Research).

Tree care expenditure information was provided by Brian Jorgenson (City of 

Boise, Idaho), Michael Bowman (City of Lewiston, Idaho), Earl Moran (City of 

Nampa, Idaho), John Franks (City of Payette, Idaho), Paul Nelson (City of Caldwell, 

Idaho), Janet Davis and Ezekiel Willard (Idaho Tree Preservation), Mary Jane 

Fields (DG Turf Farm & Nursery), Kevin Allen (Pro Care Landscape Services), and 

Eddie Brock (The Lawn Company Maintenance).

Dr. John Lloyd (University of Idaho), Dick Post (University of Nevada Cooperative Extension), Dave Stephenson (Idaho Department of Lands, Urban and Community Forestry Coordinator), and Susan Stead (Nevada Department of Conservation 

and Natural Resources, Division of Forestry) provided helpful reviews of this work. 

Mark Buscaino, Keith Cline, and Barbara Hollenbeck (U.S. Department of 

Agriculture, Forest Service, State and Private Forestry); Susan Stead (Nevada 

Department of Conservation and Natural Resources, Division of Forestry); and 

Dave Stephenson (Idaho Department of Lands, Urban and Community Forestry 

Coordinator) provided invaluable support for this project.
68

GENERAL TECHNICAL REPORT PSW-GTR-206 

References

Agrimet. 2006. Pacific Northwest Cooperative Agricultural Weather Network. 

Historical dayfile data access. http://www.usbr.gov/pn/agrimet/webaghrread.

html. (30 March 2006).

Akbari, H.; Davis, S.; Dorsano, S.; Huang, J.; Winnett, S., eds. 1992. Cooling 

our communities: a guidebook on tree planting and light-colored surfacing. 

Washington, DC: U.S. Department of the Interior, Environmental Protection 

Agency. 26 p.

Alliance for Community Trees. 2006. Tree by tree, street by street. http://actrees.

org. (27 January 2007).

American Forests. 2001. Regional ecosystem analysis for the Willamette/Lower 

Columbia region of northwestern Oregon and southwestern Washington State. 

Calculating the value of nature. Washington, DC: American Forests. 16 p.

American Forests. 2004. Urban Ecological Analysis, Montgomery, AL. 

Washington, DC. 12 p.

Ames, M.J. 1987. Solar friendly trees report. Portland, OR: City of Portland 

Energy Office. [Pages unknown].

Anderson, L.M.; Cordell, H.K. 1988. Residential property values improve by 

landscaping with trees. Southern Journal of Applied Forestry. 9: 162–166.

Bedker, P.J.; O’Brien, J.G.; Mielke, M.E. 1995. How to prune trees. NA-FR01-95. [Newtown Square, PA]: U.S. Department of Agriculture, Forest Service, 

Northeastern Area State and Private Forestry. 28 p.

Bell, J. 2006. Personal communication. Stormwater management costs. Stormwater 

Program Coordinator, Public Works Department, City of Boise, P.O. Box 500, 

Boise, ID 83701-0500.

Benjamin, M.T.; Winer, A.M. 1998. Estimating the ozone-forming potential of 

urban trees and shrubs. Atmospheric Environment. 32: 53–68.

Bernhardt, E.; Swiecki, T.J. 1993. The state of urban forestry in California: 

results of the 1992 California urban forest survey. Sacramento: California 

Department of Forestry and Fire Protection. 51 p.

Brandle, J.R.; Nickerson, H.D.; 1996. Windbreaks for snow management. EC96-

1770-X. Lincoln, NE: University of Nebraska Extension. [Pages unknown.]
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

69

Bratkovich, S.M. 2001. Utilizing municipal trees: ideas from across the country. 

NA-TP-06-01. Newtown Square, PA: U.S. Department of Agriculture, Forest 

Service, Northeastern Area State and Private Forestry. 91 p.

Brenzel, K.N., ed. 2001. Sunset western garden book. 7th ed. Menlo Park, CA: 

Sunset Books, Inc. 768 p. 

Brock J.H. 1998. Invasion, ecology and management of Elaeagnus angustifolia

(Russian olive) in the Southwestern U.S.A. In: Starfinger, U.; Edwards, K.; 

Kowarik, I.; Williamson, M., eds. Plant invasions: ecological mechanisms and 

human responses. Leiden, The Netherlands: Backhuys Publishers. 372 p.

Cappiella, K.; Schueler, T.; Wright, T. 2005. Urban watershed forestry manual. 

Ellicott City, MD: Center for Watershed Protection. 138 p.

Cardelino, C.A.; Chameides, W.L. 1990. Natural hydrocarbons, urbanization, 

and urban ozone. Journal of Geophysical Research. 95(9): 13971–13979.

Chameides W.L.; Lindsay, R.W.; Richardson, J.; Kiang, C.S. 1988. The role of 

biogenic hydrocarbons in urban photochemical smog: Atlanta as a case study. 

Science. 241: 1473–1475.

Chicago Climate Exchange. 2007. About CCX. http://www.chicagoclimatex.com/

about/index.html. (21 January 2007).

CO2e.com. 2007. CO2e market size and pricing. http://www.co2e.com/strategies/

AdditionalInfo.asp?PageID=273#1613. (21 January 2007).

Cook, D.I. 1978. Trees, solid barriers, and combinations: alternatives for noise 

control. In: Proceedings of the National Urban Forestry Conference. ESF Pub. 

80-003. Syracuse, NY: State University of New York: 330–334.

Costello, L.R. 2000. Training young trees for structure and form. [Video] V99-

A. Oakland, CA: University of California, Agriculture and Natural Resources, 

Communication Services Cooperative Extension Service.

Costello, L.R.; Jones, K.S. 2003. Reducing infrastructure damage by tree roots: a 

compendium of strategies. Cohasset, CA: Western Chapter of the International 

Society of Arboriculture. 119 p.

Dwyer, J.F.; McPherson, E.G.; Schroeder, H.W.; Rowntree, R.A. 1992.

Assessing the benefits and costs of the urban forest. Journal of Arboriculture. 

18(5): 227–234.
70

GENERAL TECHNICAL REPORT PSW-GTR-206 

Dwyer, M.C.; Miller, R.W. 1999. Using GIS to assess urban tree canopy 

benefits and surrounding greenspace distributions. Journal of Arboriculture. 

25(2): 102–107.

European Climate Exchange. 2006. Historic data—ECX CFI futures contract. 

http://www.europeanclimateexchange.com. (29 August 2006).

Fazio, J.R. [N.d.]. Tree City USA Bulletin Series. Lincoln, NE: The National 

Arbor Day Foundation.

Geiger, J. 2001. Save dollars with shade. Davis, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station. 4 p. http://www.

fs.fed.us/psw/programs/cufr/products/3/cufr_149.pdf. (25 January 2007). 

Geiger, J. 2002a. Green plants or power plants? Davis, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station. 4 p. http://www.

fs.fed.us/psw/programs/cufr/products/3/cufr_148.pdf. (25 January 2007).

Geiger, J. 2002b. Where are all the cool parking lots? Davis, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest Research Station. 4 p. http://

www.fs.fed.us/psw/programs/cufr/products/3/cufr_151.pdf. (25 January 2007).

Geiger, J. 2003. Is all your rain going down the drain? Davis, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest Research Station. 4 p. http://

www.fs.fed.us/psw/programs/cufr/products/cufr_392_rain_down_the_drain.pdf. 

(25 January 2007).

Geiger, J. 2006. Trees—the air pollution solution. Davis, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station. 4 p. http://www.

fs.fed.us/psw/programs/cufr/products/3/ cufr_658_Air_pollution_solution.pdf. 

(25 January 2007).

Gilman, E.F. 1997. Trees for urban and suburban planting. Albany, NY: Delmar 

Publishing. 688 p.

Gilman, E.F. 2002. An illustrated guide to pruning. 2nd ed. Albany, NY: Delmar 

Publishing. 256 p.

Gonzalez, S. 2004. Personal communication. Assistant maintenance 

superintendent, City of Vallejo, 111 Amador St., Vallejo, CA 94590.

Grant, R.H.; Heisler, G.M.; Goa, W. 2002. Estimation of pedestrian level UV 

exposure under trees. Photochemistry and Photobiology. 75(4): 369–376.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

71

Guenther, A.B.; Monson, R.K.; Fall, R. 1991. Isoprene and monoterpene 

emission rate variability: observations with eucalyptus and emission rate 

algorithm development. Journal of Geophysical Research. 96: 10799–10808.

Guenther, A.B.; Zimmermann, P.R.; Harley, P.C.; Monson, R.K.; Fall, R. 

1993. Isoprene and monoterpene emission rate variability: model evaluations and 

sensitivity analyses. Journal of Geophysical Research. 98: 12609–12617.

Hammer, T.T.; Coughlin, R.; Horn, E. 1974. The effect of a large urban park on 

real estate value. Journal of the American Institute of Planning. July: 274–275.

Hammond J.; Zanetto, J.; Adams, C. 1980. Planning solar neighborhoods. 

Sacramento, CA: California Energy Commission. 179 p.

Hargrave, R.; Johnson, G.R.; Zins, M.E. 2002. Planting trees and shrubs for 

long-term health. MI-07681-S. St. Paul, MN: University of Minnesota Extension 

Service. 12 p.

Harris, R.W.; Clark, J.R.; Matheny, N.P. 2003. Arboriculture. 4th ed. Englewood 

Cliffs, NJ: Regents/Prentice Hall. 592 p.

Hauer, R.J.; Hruska, M.C.; Dawson, J.O. 1994. Trees and ice storms: the 

development of ice storm-resistant urban tree populations. Special Publ. 

94-1. Urbana, IL: Department of Forestry, University of Illinois at UrbanaChampaign. 12 p.

Haugen, L.M. 1998. How to identify and manage Dutch elm disease. NA-PR-07-

98. [Newtown Square, PA]: U.S. Department of Agriculture, Forest Service, 

Northeastern Area State and Private Forestry. 26 p.

Heisler, G.M. 1986. Energy savings with trees. Journal of Arboriculture. 12(5): 

113–125.

Hightshoe, G.L. 1988. Native trees, shrubs, and vines for urban and rural 

America. New York: Van Nostrand Reinhold. 832 p.

Hildebrandt, E.W.; Kallett, R.; Sarkovich, M.; Sequest, R. 1996. Maximizing 

the energy benefits of urban forestation. In: Proceedings of the ACEEE 1996 

summer study on energy efficiency in buildings. Washington, DC: American 

Council for an Energy Efficient Economy: 121–131. Vol. 9.

Hudson, B. 1983. Private sector business analogies applied in urban forestry. 

Journal of Arboriculture. 9(10): 253–258.

Hull, R.B. 1992. How the public values urban forests. Journal of Arboriculture. 

18(2): 98–101.
72

GENERAL TECHNICAL REPORT PSW-GTR-206 

Hunter, J. 2000. Ailanthus altissima (Miller) Swingle. In: Bossard, C.C.; Randall, 

J.M.; Hoshovsky, M.C., eds. Invasive plants of California’s wildlands. Berkeley: 

University of California Press, Berkeley: 32–36.

Idaho Power Company. 2006. Schedule 1. Residential service electricity rates. 

http://www.idahopower.com/aboutus/regulatoryinfo/tariffPdf.asp?id=156&.pdf. 

(15 March 2006).

Intergovernmental Panel on Climate Change [IPCC]. 2001. Technical summary. 

Climate change 2001: the scientific basis. Geneva. 63 p. 

Intermountain Gas Company. 2006. Prices. RS-1 Residential service. http://www.

intgas.com/aboutbilling/prices.html. (15 March 2006).

International Society of Arboriculture [ISA]. 1992. Avoiding tree and utility 

conflicts. Savoy, IL. 4 p.

International Society of Arboriculture. 2006. Welcome to the International 

Society of Arboriculture. http://www.isa-arbor.com/home.aspx. (27 January 

2007). 

Jo, H.K.; McPherson, E.G. 1995. Carbon storage and flux in residential greenspace. Journal of Environmental Management. 45: 109–133.

Jorgenson, B. 2006. Personal communication. City forester, Boise Parks and 

Recreation Department, Community Forestry Unit, 4969 Dorman St., Boise, ID, 

83705.

Kaplan, R. 1992. Urban forestry and the workplace. In: Gobster, P.H., ed. 

Managing urban and high-use recreation settings. Gen. Tech. Rep. NC-163. 

St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central 

Research Station:41–45.

Kaplan, R.; Kaplan, S. 1989. The experience of nature: a psychological 

perspective. Cambridge, United Kingdom: Cambridge University Press. 360 p.

Kim, S.; Byun, D.W.; Cheng, F.-Y.; Czader, B.; Stetson, S.; Nowak, D.; 

Walton, J.; Estes, M.; Hitchcock, D. 2005. Modeling effects of land use land 

cover changes on meteorology and air quality in Houston, Texas, over the last 

two decades. In: Proceedings of the 2005 Atmospheric Sciences Air Quality 

Conference. [Place of publication unknown]. Available at: http://ams.confex.com/

ams/pdfpapers/92244.pdf. (23 January 2007).

Lewis, C.A. 1996. Green nature/human nature: the meaning of plants in our lives. 

Chicago: University of Illinois Press. 176 p.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

73

Luley, C.J.; Bond, J. 2002. A plan to integrate management of urban trees into air 

quality planning. Naples, NY: Davey Resource Group. 61 p.

Maco, S.E.; McPherson, E.G. 2003. A practical approach to assessing structure, 

function, and value of street tree populations in small communities. Journal of 

Arboriculture. 29(2): 84–97.

Marion, W.; Urban, K. 1995. User’s manual for TMY2s—typical meteorological 

years. Golden, CO: National Renewable Energy Laboratory. 49 p.

Markwardt, L.J. 1930. Comparative strength properties of woods grown in 

the United States. Tech. Bull. 158. Washington, DC: U.S. Department of 

Agriculture. 38 p.

McHale, M. 2003. Carbon credit markets: Is there a role for community 

forestry? In: Kollin, C., ed. 2003 national urban forest conference proceedings. 

Washington, DC: American Forests: 74–77.

McKenzie, D.; Gedalof, Z.; Peterson, D.L.; Mote, P. 2004. Climate change, 

wildfire, and conservation. Conservation Biology. 18(4): 890–902.

McPherson, E.G. 1984. Planting design for solar control. In: McPherson, E.G., 

ed. Energy-conserving site design. Washington, DC: American Society of 

Landscape Architects: 141–164. Chapter 8.

McPherson, E.G. 1992. Accounting for benefits and costs of urban greenspace. 

Landscape and Urban Planning. 22: 41–51.

McPherson, E.G. 1993. Evaluating the cost effectiveness of shade trees for 

demand-side management. The Electricity Journal. 6(9): 57–65.

McPherson, E.G. 1995. Net benefits of healthy and productive forests. In: Bradley, 

G.A., ed. Urban forest landscapes: integrating multidisciplinary perspectives. 

Seattle, WA: University of Washington Press: 180–194.

McPherson, E.G. 2000. Expenditures associated with conflicts between street 

tree root growth and hardscape in California. Journal of Arboriculture. 26(6): 

289–297.

McPherson, E.G. 2001. Sacramento’s parking lot shading ordinance: 

environmental and economic costs of compliance. Landscape and Urban 

Planning. 57: 105–123.

McPherson, E.G.; Mathis, S., eds. 1999. Proceedings of the Best of the 

West summit. Sacramento, CA: Western Chapter, International Society of 

Arboriculture. 93 p.
74

GENERAL TECHNICAL REPORT PSW-GTR-206 

McPherson, E.G.; Muchnick, J. 2005. Effects of tree shade on asphalt concrete 

pavement performance. Journal of Arboriculture. 31(6): 303–309.

McPherson, E.G.; Nowak, D.J.; Heisler, G.; Grimmond, S.; Souch, C.; Grant, 

R.; Rowntree, R.A. 1997. Quantifying urban forest structure, function, and 

value: Chicago’s Urban Forest Climate Project. Urban Ecosystems. 1: 49–61.

McPherson, E.G.; Nowak, D.J.; Rowntree, R.A. 1994. Chicago’s urban forest 

ecosystem: results of the Chicago Urban Forest Climate Project. Gen. Tech. Rep. 

NE-186. Radnor [Newtown Square], PA: U.S. Department of Agriculture, Forest 

Service, Northeastern Research Station. 201 p. 

McPherson, E.G.; Peper, P.J. 1995. Infrastructure repair costs associated with 

street trees in 15 cities. In: Watson, G.W.; Neely, D., eds. Trees and building sites. 

Champaign, IL: International Society of Arboriculture: 49–63.

McPherson, E.G.; Sacamano, P.L.; Wensman, S. 1993. Modeling benefits and 

costs of community tree plantings. Albany, CA: U.S. Department of Agriculture, 

Forest Service, Pacific Southwest Research Station. 170 p.

McPherson, E.G.; Simpson, J.R. 1999. Carbon dioxide reduction through urban 

forestry: guidelines for professional and volunteer tree planters. Gen. Tech. Rep. 

PSW-171. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific 

Southwest Research Station. 237 p.

McPherson, E.G., Simpson, J.R. 2002. A comparison of municipal forest benefits 

and costs in Modesto and Santa Monica, CA, USA. Urban Forestry and Urban 

Greening. 1: 61–74.

McPherson, E.G.; Simpson, J.R. 2003. Potential energy savings in buildings 

by an urban tree planting programme in California. Urban Forestry and Urban 

Greening. 2(2): 73–86.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Gardner, S.L.; Vargas, K.E.; 

Maco, S.E.; Xiao, Q. 2006a. Coastal Plain community tree guide: benefits, 

costs, and strategic planting. Gen Tech. Rep. PSW-GTR-201. Albany, CA: 

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

Station. 99 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Gardner, S.L.; Vargas, K.E.; 

Maco, S.E.; Xiao, Q. 2006b. Piedmont community tree guide: benefits, 

costs, and strategic planting. Gen Tech. Rep. PSW-GTR-200. Albany, CA: 

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

Station. 95 p. 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

75

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Gardner, S.L.; Vargas, K.E.; 

Xiao, Q. [In press]. Northeast community tree guide: benefits, costs, and 

strategic planting. Gen Tech. Rep. PSW-GTR-202. Albany, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest Research Station. 102 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Maco, S.E.; Gardner, S.L.; 

Cozad, S.K.; Xiao, Q. 2006c. Midwest community tree guide: benefits, 

costs, and strategic planting. Gen. Tech. Rep. PSW-GTR-199. Albany, CA: 

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

Station. 85 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Maco, S.E.; Xiao, Q.; Hoefer, P.J. 

2003. Northern mountain and prairie community tree guide: benefits, costs, and 

strategic planting. Albany, CA: U.S. Department of Agriculture, Forest Service, 

Pacific Southwest Research Station. 88 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Maco, S.E.; Xiao, Q.; Mulrean, 

E. 2004. Desert Southwest community tree guide: benefits, costs, and strategic 

planting. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific 

Southwest Research Station. 65 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Scott, K.; Xiao, Q. 2000. Tree 

guidelines for coastal southern California communities. Sacramento, CA: Local 

Government Commission. 97 p.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Xiao, Q. 1999a. Benefit-cost 

analysis of Modesto’s municipal urban forest. Journal of Arboriculture. 25(5): 

235–248.

McPherson, E.G.; Simpson, J.R.; Peper, P.J.; Xiao, Q. 1999b. Tree guidelines 

for San Joaquin Valley communities. Sacramento, CA: Local Government 

Commission. 63 p.

Metro. 2002. Green streets: innovative solutions for stormwater and stream 

crossings. Portland, OR: Metro. 144 p.

Miller, R.W. 1997. Urban forestry: planning and managing urban greenspaces. 2d 

ed. Upper Saddle River, NJ: Prentice-Hall. 502 p.

More, T.A.; Stevens, T.; Allen, P.G. 1988. Valuation of urban parks. Landscape 

and Urban Planning. 15: 139–152.

Morgan, R. [N.d.]. An introductory guide to community and urban forestry in 

Washington, Oregon, and California. Portland, OR: World Forestry Center. 25 p.
76

GENERAL TECHNICAL REPORT PSW-GTR-206 

Morgan, R. 1993. A technical guide to urban and community forestry. Portland, 

OR: World Forestry Center. 49 p.

National Arbor Day Foundation. 2006. Color your world. http://www.arborday.

org. (27 January 2007).

Neely, D., ed. 1988. Valuation of landscape trees, shrubs, and other plants. 7th ed. 

Urbana, IL: International Society of Arboriculture. 50 p.

Noble, R.D.; Martin, J.L.; Jensen, K.F., eds. 1988. Air pollution effects on 

vegetation, including forest ecosystems. Proceedings of the second US–USSR 

symposium. Gov. Doc. A13.42/2:2:A:7. Broomall [Newtown Square], PA: U.S. 

Department of Agriculture, Forest Service, Northeastern Research Station. 311 p.

Nowak, D.J. 1994. Air pollution removal by Chicago’s urban forest. In: McPherson, 

E.G.; Nowak, D.J.; Rowntree, R.A., eds. Chicago’s urban forest ecosystem: 

results of the Chicago urban forest climate project. Gen. Tech. Rep. NE-186. 

Radnor [Newtown Square], PA: U.S. Department of Agriculture, Forest Service, 

Northeastern Research Station: 63–82.

Nowak, D.J. 2000. Tree species selection, design, and management to improve 

air quality. In: Scheu, D.L., ed. 2000 ASLA annual meeting proceedings. 

Washington, DC: American Society of Landscape Architects: 23–27.

Nowak, D.J.; Civerolo, K.L.; Rao, S.T.; Sistla, G.; Luley, C.J.; Crane, D.E. 

2000. A modeling study of the impact of urban trees on ozone. Atmospheric 

Environment. 34: 1601–1613.

Nowak, D.J.; Crane, D.E. 2002. Carbon storage and sequestration by urban trees 

in the USA. Environmental Pollution. 116: 381–389.

Ottinger, R.L.; Wooley, D.R.; Robinson, N.A.; Hodas, D.R.; Babb, S.E. 1990. 

Environmental costs of electricity. New York: Oceana Publications. 769 p.

Parsons, R.; Tassinary, L.G.; Ulrich, R.S.; Hebl, M.R.; Grossman-Alexander, 

M. 1998. The view from the road: implications for stress recovery and 

immunization. Journal of Environmental Psychology. 18(2): 113–140.

Pearce, D 2003. The social cost of carbon and its policy implications. Oxford 

Review of Public Policy. 19(3): 362–384.

Peper, P.J.; McPherson, E.G. 2003. Evaluation of four methods for estimating leaf 

area of isolated trees. Urban Forestry and Urban Greening. 2(1): 19–29.

Peper, P.J.; McPherson, E.G.; Simpson, J.R.; Gardner, S.L.; Vargas, K.E. 

[In press]. City of Boise, Idaho, Municipal Forest Resource Analysis. Internal 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

77

Tech. Rep. Davis, CA: U.S. Department of Agriculture, Forest Service, Pacific 

Southwest Research Station, Center for Urban Forest Research.

Pillsbury, N.H.; Reimer, J.L.; Thompson, R.P. 1998. Tree volume equations for 

fifteen urban species in California. Tech. Rep. 7. San Luis Obispo, CA: Urban 

Forest Ecosystems Institute, California Polytechnic State University. 56 p.

Platt, R.H.; Rowntree, R.A.; Muick, P.C., eds. 1994. The ecological city. Boston, 

MA: University of Massachusetts. 292 p.

Pokorny, J.D. 2003. Urban tree risk management: a community guide to 

program design and implementation. NA-TP-03-03. Newtown Square, PA: U.S. 

Department of Agriculture, Forest Service, Northeastern Area State and Private 

Forestry. [Pages unknown].

Post, R. 2007. Personal communication. Former Western Area Director, University 

of Nevada Cooperative Extension, Reno, NV [no current address available].

Ramsay, S. 2002. Personal communication. Executive Director, Trees Forever, 770 

7

th Ave., Marion, IA 52302.

Richards, N.A.; Mallette, J.R.; Simpson, R.J.; Macie, E.A. 1984. Residential 

greenspace and vegetation in a mature city: Syracuse, New York. Urban Ecology. 

8: 99–125.

Rosenzweig, C.; Solecki, W.; Parshall, L.; Hodges, S. 2006. Mitigating New 

York City’s heat island with urban forestry, living roofs, and light surfaces. New 

York City regional heat island initiative final report 06-06. Albany, NY: New 

York State Energy Research and Development Authority. 173 p.

Sand, M. 1991. Planting for energy conservation in the North. Minneapolis, MN: 

Minnesota Department of Natural Resources. 19 p.

Sand, M. 1993. Energy saving landscapes: the Minnesota homeowner’s guide. 

Minneapolis, MN: Minnesota Department of Natural Resources. [Pages 

unknown].

Sand, M. 1994. Design and species selection to reduce urban heat island and 

conserve energy. In: Proceedings from the sixth national urban forest conference: 

growing greener communities. Washington, DC: American Forests. 282 p.

Schroeder, H.W.; Cannon, W.N. 1983. The esthetic contribution of trees to 

residential streets in Ohio towns. Journal of Arboriculture. 9: 237–243.

Schroeder, T. 1982. The relationship of local park and recreation services to 

residential property values. Journal of Leisure Research. 14: 223–234.
78

GENERAL TECHNICAL REPORT PSW-GTR-206 

Scott, K.I.; McPherson, E.G.; Simpson, J.R. 1998. Air pollutant uptake by 

Sacramento’s urban forest. Journal of Arboriculture. 24(4): 224–234.

Scott, K.I.; Simpson, J.R.; McPherson, E.G. 1999. Effects of tree cover on parking 

lot micro-climate and vehicle emissions. Journal of Arboriculture. 25(3): 129–142.

Simpson, J.R. 1998. Urban forest impacts on regional space conditioning energy 

use: Sacramento County case study. Journal of Arboriculture. 24(4): 201-214.

Smith, W.H. 1990. Air pollution and forests. New York: Springer-Verlag. 618 p.

Smith, W.H.; Dochinger, L.S. 1976. Capability of metropolitan trees to reduce 

atmospheric contaminants. In: Santamour, F.S.; Gerhold, H.D.; Little, S., eds. 

Better trees for metropolitan landscapes. Gen. Tech. Rep. NE-22. Upper Darby 

[Newtown Square], PA: U.S. Department of Agriculture, Forest Service, 

Northeastern Research Station: 49–60.

Sullivan, W.C.; Kuo, E.E. 1996. Do trees strengthen urban communities, reduce 

domestic violence? Arborist News. 5(2): 33–34.

Summit, J.; McPherson, E.G. 1998. Residential tree planting and care: a study 

of attitudes and behavior in Sacramento, California. Journal of Arboriculture. 

24(2): 89–97.

Sydnor, T.D.; Gamstetter, D.; Nichols, J.; Bishop, B.; Favorite, J.; Blazer, 

C.; Turpin, L. 2000. Trees are not the root of sidewalk problems. Journal of 

Arboriculture. 26:20–29.

Taha, H. 1996. Modeling impacts of increased urban vegetation on ozone air 

quality in the South Coast Air Basin. Atmospheric Environment. 30: 3423–3430.

Tellman, B. 1997. Exotic pest plant introduction in the American Southwest. 

Desert Plants. 13(1): 3–10.

Thompson, R.P.; Ahern, J.J. 2000. The state of urban and community forestry in 

California. San Luis Obispo, CA: Urban Forest Ecosystems Institute, California 

Polytechnic State University. 48 p.

Treelink. 2007. Improving urban and community forests by providing Internetbased information, tools, and inspiration. http://www.treelink.org. (29 June 

2007).

Tretheway, R.; Manthe, A. 1999. Skin cancer prevention: another good reason to 

plant trees. In: McPherson, E.G.; Mathis, S. Proceedings of the Best of the West 

summit. Davis, CA: University of California: 72–75.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

79

Tschantz, B.A.; Sacamano, P.L. 1994. Municipal tree management in the United 

States. Kent, OH: Davey Resource Group. 71 p.

Tyrvainen, L. 1999. Monetary valuation of urban forest amenities in Finland. Res. 

Pap. 739. Vantaa, Finland: Finnish Forest Research Institute. 129 p.

Ulrich, R.S. 1985. Human responses to vegetation and landscapes. Landscape and 

Urban Planning. 13: 29–44.

Urban, J. 1992. Bringing order to the technical dysfunction within the urban 

forest. Journal of Arboriculture. 18(2): 85–90.

Urban Horticulture Institute. 2003. Recommended urban trees: site assessment 

and tree selection for stress tolerance. http://www.hort.cornell.edu/UHI/outreach/

recurbtree/index.html. (7 February 2007).

U.S. Census Bureau. 2006. State and county quick facts. http://quickfacts.census.

gov/qfd/index.html. (March 2006).

U.S. Department of Agriculture, Forest Service [USDA FS]. 2006a. i-Tree: tools 

for assessing and managing community forests. http://www.itreetools.org. (27 

January 2007).

U.S. Department of Agriculture, Forest Service [USDA FS]. 2006b. Urban tree 

cover and air quality planning. http://www.treescleanair.org. (21 January 2007).

U.S. Department of Agriculture, Natural Resource Conservation Service, 

Agroforestry Center [USDA NRCS Agroforesty Center]. 2005. Working trees 

for treating waste. Western Arborist. 31: 50–52.

U.S. Department of Agriculture, Soil Conservation Service [USDA SCS]. 

1986. Urban hydrology for small watersheds. Technical Release 55. 2nd ed. 

Washington, DC. 164 p.

U.S. Department of Transportation. 1995. Highway traffic noise analysis 

and abatement policy and guidance. Washington, DC: Federal Highway 

Administration. 67 p.

U.S. Environmental Protection Agency [US EPA]. 1998. Ap-42 Compilation 

of air pollutant emission factors. 5th ed. Research Triangle Park, NC. Volume I. 

[Pages unknown.]

U.S. Environmental Protection Agency [US EPA]. 2003. E-GRID (E-GRID2002 

Edition). http://www.epa.gov/cleanenergy/egrid/index.htm. (6 December 2006).
80

GENERAL TECHNICAL REPORT PSW-GTR-206 

U.S. Environmental Protection Agency [U.S. EPA]. 2006. Green book: 

nonattainment areas for criteria pollutants. http://www.epa.gov/air/oaqps/

greenbk/index.html. (6 December 2006).

van Rentergehm, T.; Botteldooren, D.; Cornelis, W.M.; Gabriels, D.; 2002. 

Reducing screen-induced refraction of noise barriers in wind by vegetative 

screens. Acta Acustica United with Acustica. 88: 231–238.

Vargas, K.E.; McPherson, E.G.; Simpson J.R.; Peper, P.J.; Gardner, S.L.; 

Xiao, Q. 2006. City of Albuquerque, New Mexico, municipal forest resource 

analysis. Internal Tech. Rep. Davis, CA: U.S. Department of Agriculture, 

Forest Service, Pacific Southwest Research Station, Center for Urban Forest 

Research. 51 p.

Vargas, K.E.; McPherson, E.G.; Simpson J.R.; Peper, P.J.; Gardner, S.L.; 

Xiao, Q. [In press]. Interior West community tree guide: benefits, costs, and 

strategic planting. Gen Tech. Rep. PSW-GTR-205. Albany, CA: U.S. Department 

of Agriculture, Forest Service, Pacific Southwest Research Station.

Wang, M.Q.; Santini, D.J. 1995. Monetary values of air pollutant emissions in 

various U.S. regions. Transportation Research Record 1475: 33–41. 

Watson, G.W.; Himelick, E.B. 1997. Principles and practice of planting trees and 

shrubs. Savoy, IL: International Society of Arboriculture. 199 p.

Wing, E. 2006. Personal communication. Boise GIS databases. GIS Programmer 

Analyst, GIS Division, Public Works Department, City of Boise, P.O. Box 500, 

Boise, ID 83701.

Wolf, K.L. 1999. Nature and commerce: human ecology in business districts. In: 

Kollin, C., ed. Building cities of green: proceedings of the 1999 national urban 

forest conference. Washington, DC: American Forests: 56–59.

Xiao, Q.; McPherson, E.G. 2002. Rainfall interception by Santa Monica’s 

municipal urban forest. Urban Ecosystems. 6: 291–302. 

Xiao, Q.; McPherson, E.G.; Simpson, J.R.; Ustin, S.L. 1998. Rainfall 

interception by Sacramento’s urban forest. Journal of Arboriculture. 24(4): 

235–244.

Xiao, Q.; McPherson, E.G.; Simpson, J.R.; Ustin, S.L. 2000. Winter rainfall 

interception by two mature open grown trees in Davis, California. Hydrological 

Processes. 14(4): 763–784.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

81

Appendix 1: Additional Resources

Additional information regarding urban and community forestry program design 

and implementation can be obtained from the following sources:

Utilizing Municipal Trees: Ideas From Across the Country by S.M. Bratkovich

Urban Forestry: Planning and Managing Urban Greenspaces by R.W. Miller 

An Introductory Guide to Community and Urban Forestry in Washington, Oregon, 

and California by N.R. Morgan

A Technical Guide to Urban and Community Forestry by N.R. Morgan

Urban Tree Risk Management: A Community Guide to Program Design and 

Implementation edited by J.D. Pokorny 

For additional information on tree selection, planting, establishment, and care see 

the following resources:

Alliance for Community Trees: http://actrees.org

How to Prune Trees by P.J. Bedker, J.G. O’Brien, and M.E. Mielke

Training Young Trees for Structure and Form, a video by L.R. Costello

An Illustrated Guide to Pruning by E.F. Gilman

Planting Trees and Shrubs for Long-Term Health by R. Hargrave, G.R. Johnson, 

and M.E. Zins

Arboriculture, 4th ed., by R.W. Harris, J.R. Clark, and N.P. Matheny 

Trees and Ice Storms: The Development of Ice Storm-Resistant Urban Tree 

Populations, by R.J. Hauer, M.C. Hruska, and J.O. Dawson 

How to Identify and Manage Dutch Elm Disease by L.M. Haugen

Native Trees, Shrubs, and Vines for Urban and Rural America by G.L. Hightshoe

International Society of Arboriculture: http://www.isa-arbor.com, including their 

Tree City USA Bulletin series by J.R. Fazio

National Arbor Day Foundation: http://www.arborday.org

TreeLink: http://www.treelink.org 

Trees for Urban and Suburban Landscapes by E.F. Gilman 
82

GENERAL TECHNICAL REPORT PSW-GTR-206 

The Urban Horticulture Institute: http://www.hort.cornell.edu/UHI/outreach/ 

recurbtree/index.html

Principles and Practice of Planting Trees and Shrubs by G.W. Watson and E.B. 

Himelick

These suggested references are only a starting point. Your local cooperative 

extension agent, urban forester, or state forestry agency can provide you with up-todate and local information.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

83

Appendix 2: Benefit–Cost Information Tables

Information in this appendix can be used to estimate benefits and costs associated with proposed tree plantings. The tables contain data for representative small 

(crabapple), medium (Norway maple), and large (white ash) deciduous trees and a 

representative conifer (blue spruce) (see “Common and Scientific Names” section). 

Data are presented as annual values for each 5-year interval after planting (tables 

6 to 17). Annual values incorporate effects of tree loss. Based on the results of 

our survey, we assume that 43.1 percent of the trees planted die by the end of the 

40-year period.

For the benefits tables (tables 6, 9, 12, 15), there are two columns for each 5-

year interval. In the first column, values describe resource units (RUs): for example, 

the amount of air conditioning energy saved in kilowatt hours per year per tree, air 

pollutant uptake in pounds per year per tree, and rainfall intercepted in gallons per 

year per tree. Energy and CO2 benefits for residential yard trees are broken out by 

tree location to show how shading effects differ among trees opposite west-, south-, 

and east-facing building walls. The second column for each 5-year interval contains 

dollar values obtained by multiplying RUs by local prices (e.g., kWh saved [RU] × 

$/kWh). 

In the costs tables (tables 7, 10, 13, 16), costs are broken down into categories 

for yard and public trees. Costs for yard trees do not differ by planting location (i.e., 

east, west, south walls). Although tree purchase and planting costs occur at year 1, 

we divided this value by 5 years to derive an average annual cost for the first 5-year 

period. All other costs are the estimated values for each year and not values averaged over 5 years.

Total net benefits are calculated by subtracting total costs from total benefits 

and are presented in tables 8, 11, 14, and 17. Data are presented for a yard tree 

opposite west-, south-, and east-facing walls, as well as for the public tree.

The last column in each table presents 40-year-average annual values. These 

numbers were calculated by dividing the total costs and benefits by 40 years.
84

GENERAL TECHNICAL REPORT PSW-GTR-206 

Table 6—Annual benefits at 5-year intervals and 40-year average for a representative small tree (crabapple) Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40 40-year average Benefits/tree RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Cooling (kWh): Yard: west 8 0.65 56 4.61 120 9.87 179 14.68 224 18.38 263 21.54 283 23.19 296 24.29 179 14.65 Yard: south 6 0.51 37 2.99 73 5.99 107 8.81 138 11.29 163 13.40 180 14.78 193 15.83 112 9.20 Yard: east 7 0.53 40 3.29 84 6.85 124 10.15 156 12.80 184 15.07 201 16.50 214 17.55 126 10.34 Public 6 0.51 36 2.94 69 5.67 99 8.15 124 10.13 144 11.82 158 12.92 168 13.74 100 8.23 Heating (therms): Yard: west 0.58 0.67 2.77 3.23 4.70 5.48 6.26 7.30 7.08 8.26 7.76 9.06 7.94 9.26 7.96 9.29 5.63 6.57 Yard: south 0.59 0.69 2.67 3.12 4.17 4.87 5.28 6.16 5.65 6.59 5.94 6.92 5.89 6.88 5.76 6.73 4.49 5.24 Yard: east 0.55 0.64 2.42 2.82 3.92 4.57 5.11 5.96 5.72 6.67 6.22 7.25 6.37 7.44 6.42 7.49 4.59 5.36 Public 0.61 0.71 3.09 3.61 5.48 6.39 7.47 8.72 8.66 10.10 9.66 11.27 10.04 11.72 10.23 11.94 6.91 8.06 Net energy (kWh): Yard: west 25 1.33 137 7.84 258 15.34 362 21.98 432 26.64 490 30.60 515 32.45 530 33.58 344 21.22 Yard: south 24 1.20 115 6.11 195 10.86 262 14.98 303 17.88 337 20.33 353 21.66 362 22.56 244 14.45 Yard: east 23 1.17 111 6.11 198 11.42 274 16.11 324 19.47 366 22.32 388 23.93 402 25.05 261 15.70 Public 24 1.22 127 6.55 230 12.06 318 16.87 377 20.24 427 23.09 452 24.63 467 25.68 303 16.29 Net carbon dioxide (lb): Yard: west 16 0.05 90 0.30 180 0.60 260 0.87 319 1.07 371 1.24 399 1.33 420 1.40 257 0.86 Yard: south 15 0.05 75 0.25 138 0.46 196 0.65 238 0.79 275 0.92 298 1.00 317 1.06 194 0.65 Yard: east 15 0.05 74 0.25 143 0.48 206 0.69 252 0.84 294 0.98 320 1.07 340 1.14 205 0.69 Public 15 0.05 79 0.26 151 0.50 215 0.72 262 0.88 305 1.02 330 1.10 350 1.17 214 0.71 Air pollution (lb)a Ozone uptake 0.010 0.01 0.058 0.03 0.117 0.06 0.178 0.09 0.234 0.12 0.289 0.15 0.338 0.17 0.386 0.20 0.20 0.10 Nitrogen dioxide uptake + avoided 0.020 0.01 0.117 0.06 0.229 0.12 0.331 0.17 0.409 0.21 0.476 0.24 0.516 0.26 0.546 0.28 0.33 0.17 Sulfur dioxide uptake + avoided 0.034 0 0.216 0.01 0.443 0.03 0.652 0.04 0.820 0.05 0.964 0.06 1.051 0.06 1.114 0.07 0.66 0.04 Small particulate matter uptake + avoided 0.007 0.01 0.046 0.04 0.107 0.10 0.180 0.17 0.246 0.23 0.259 0.24 0.266 0.24 0.271 0.25 0.17 0.16 Volatile organic compounds avoided 0.003 0 0.020 0 0.040 0.01 0.058 0.01 0.073 0.01 0.086 0.01 0.093 0.01 0.098 0.01 0.06 0.01 Biogenic volatile organic compounds released 0 0 -0.001 0 -0.002 0 -0.004 0 -0.005 0 -0.005 0 -0.005 0 -0.005 0 0 0 Total air pollution avoided + net uptake 0.074 0.02 0.456 0.15 0.934 0.31 1.395 0.47 1.777 0.61 2.069 0.70 2.259 0.76 2.410 0.80 1.42 0.48 Hydrology (gal) Rainfall interception 8 0.04 47 0.23 94 0.47 142 0.71 187 0.93 231 1.16 271 1.35 309 1.55 161 0.81 Aesthetics and other: Yard 4.07 9.41 12.19 12.60 11.44 9.36 6.80 4.05 8.74 Public 4.54 10.51 13.62 14.07 12.78 10.45 7.59 4.53 9.76 Total benefits: Yard: west 5.51 17.93 28.91 36.63 40.70 43.05 42.68 41.39 32.10 Yard: south 5.38 16.15 24.29 29.41 31.66 32.46 31.56 30.02 25.12 Yard: east 5.35 16.14 24.87 30.58 33.30 34.52 33.90 32.59 26.41 Public 5.87 17.70 26.96 32.85 35.44 36.41 35.44 33.73 28.05 Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. RU = resource unit. a Values are the same for yard and public trees.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

85

Table 7—Annual costs (dollars per tree) at 5-year intervals and 40-year average for a 

representative small tree (crabapple)

Costs Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Tree and plantinga:

Yard 35.00 4.38 

Public 28.00 3.50 

Pruning:

Yard 0.23 0.17 0.16 2.30 2.22 2.15 2.07 2.00 1.21 

Public 5.44 6.20 5.88 5.56 5.24 4.92 4.60 4.28 5.42 

Remove and dispose:

Yard 0.08 0.82 1.35 1.87 2.36 2.83 3.28 3.71 1.85 

Public 0.26 0.98 1.61 2.23 2.81 3.38 3.91 4.42 2.22 

Pest and disease

Yard 0.03 0.07 0.11 0.15 0.18 0.21 0.23 0.26 0.14 

Public 0.02 0.06 0.10 0.13 0.15 0.17 0.18 0.19 0.11 

Infrastructure repair:

Yard 0.04 0.10 0.15 0.21 0.25 0.29 0.33 0.36 0.20

Public 0.26 0.68 1.07 1.40 1.66 1.87 2.03 2.13 1.28

Irrigation:

Yard 0 0 0 0 0 0 0 0 0

Public 1.34 0 0 0 0 0 0 0 0.18

Cleanup:

Yard 0.01 0.03 0.04 0.06 0.07 0.08 0.10 0.10 0.06 

Public 0.08 0.20 0.31 0.41 0.48 0.55 0.59 0.62 0.37 

Liability and legal:

Yard 0 0 0 0.01 0.01 0.01 0.01 0.01 0.01 

Public 0.01 0.02 0.03 0.04 0.05 0.06 0.06 0.07 0.04 

Admin./inspect/other:

Yard 0 0 0 0 0 0 0 0 0

Public 0.52 1.34 2.10 2.74 3.26 3.67 3.98 4.18 2.51 

Total costs:

 Yard 35.38 1.18 1.83 4.58 5.10 5.57 6.02 6.43 7.84

Public 35.93 9.49 11.10 12.50 13.66 14.61 15.35 15.89 15.64

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent.

a

Although tree and planting costs occur in year 1, this value was divided by 5 years to derive an average annual cost for the 

first 5-year period.

Table 8—Annual net benefits (dollars per tree) at 5-year intervals and 40-year average for 

a representative small tree (crabapple)

Total net benefits Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Yard: west -30 17 27 32 36 37 37 35 24

Yard: south -30 15 22 25 27 27 26 24 17

Yard: east -30 15 23 26 28 29 28 26 19

Public -30 8 16 20 22 22 20 18 12

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. See table 6 for annual benefits and table 7 

for annual costs.
86

GENERAL TECHNICAL REPORT PSW-GTR-206 

Table 9—Annual benefits (dollars per tree) at 5-year intervals and 40-year average for a representative medium tree (Norway maple) Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40 40-year average Benefits/tree RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Cooling (kWh): Yard: west 61 5.03 160 13.12 256 20.99 329 26.97 381 31.24 417 34.16 433 35.55 445 36.45 310 25.44 Yard: south 27 2.18 79 6.49 134 11.00 195 16.00 240 19.66 279 22.84 303 24.85 322 26.39 197 16.18 Yard: east 35 2.85 99 8.12 164 13.45 225 18.45 269 22.07 303 24.82 321 26.36 335 27.48 219 17.95 Public 25 2.01 68 5.58 112 9.17 159 13.06 194 15.89 224 18.35 243 19.89 257 21.06 160 13.12 Heating (therms): Yard: west 1.44 1.68 3.65 4.26 5.66 6.60 6.99 8.16 7.93 9.25 8.34 9.73 8.39 9.79 8.37 9.76 6.35 7.40 Yard: south 0.48 0.56 0.71 0.83 0.69 0.80 0.78 0.90 0.83 0.97 0.92 1.07 0.98 1.14 1.02 1.20 0.80 0.93 Yard: east 0.87 1.01 2.42 2.82 3.88 4.53 5.15 6.00 6.05 7.06 6.57 7.66 6.76 7.88 6.86 8.01 4.82 5.62 Public 2.12 2.47 5.34 6.23 8.33 9.72 10.46 12.20 11.97 13.96 12.74 14.87 12.95 15.11 13.03 15.20 9.62 11.22 Net energy (kWh): Yard: west 103 6.71 267 17.38 422 27.60 534 35.13 613 40.49 661 43.89 679 45.34 690 46.21 496 32.84 Yard: south 41 2.74 100 7.32 154 11.80 218 16.91 264 20.64 305 23.92 332 25.99 352 27.58 221 17.11 Yard: east 60 3.86 170 10.94 278 17.98 376 24.45 447 29.13 495 32.49 520 34.25 536 35.49 360 23.57 Public 87 4.48 224 11.80 356 18.88 466 25.26 545 29.85 597 33.22 622 35.00 639 36.25 442 24.34 Net carbon dioxide (lb): Yard: west 82 0.27 205 0.68 323 1.08 412 1.38 478 1.59 516 1.72 532 1.78 543 1.81 386 1.29 Yard: south 45 0.15 110 0.37 174 0.58 239 0.80 289 0.96 326 1.09 348 1.16 365 1.22 237 0.79 Yard: east 55 0.18 145 0.48 234 0.78 313 1.04 372 1.24 410 1.37 429 1.43 443 1.48 300 1.00 Public 62 0.21 156 0.52 247 0.83 326 1.09 385 1.29 424 1.42 443 1.48 458 1.53 313 1.04 Air pollution (lb)a

:

Ozone uptake 0.035 0.02 0.108 0.06 0.187 0.10 0.279 0.14 0.359 0.18 0.442 0.23 0.513 0.26 0.584 0.30 0.31 0.16 Nitrogen dioxide uptake 

+ avoided 0.089 0.05 0.242 0.12 0.394 0.20 0.534 0.27 0.637 0.32 0.717 0.37 0.764 0.39 0.799 0.41 0.52 0.27 

Sulfur dioxide uptake + 

avoided 0.188 0.01 0.519 0.03 0.851 0.05 1.161 0.07 1.386 0.08 1.562 0.09 1.663 0.10 1.737 0.10 1.13 0.07 

Small particulate matter 

uptake + avoided 0.019 0.02 0.068 0.06 0.144 0.13 0.246 0.23 0.344 0.32 0.438 0.40 0.447 0.41 0.453 0.42 0.27 0.25 

Volatile organic 

compounds avoided 0.017 0 0.046 0.01 0.075 0.01 0.101 0.01 0.121 0.02 0.136 0.02 0.145 0.02 0.151 0.02 0.10 0.01 

Biogenic volatile organic 

compounds released -0.002 0 -0.026 0 -0.075 -0.01 -0.142 -0.02 -0.213 -0.03 -0.286 -0.04 -0.286 -0.04 -0.286 -0.04 -0.16 -0.02

Total air pollution 

 avoided + net uptake 0.345 0.09 0.956 0.27 1.576 0.48 2.180 0.71 2.634 0.89 3.009 1.07 3.245 1.14 3.438 1.21 2.17 0.73 

Hydrology (gal)

Rainfall interception 101 0.50 308 1.54 532 2.66 796 3.98 1,023 5.12 1,259 6.30 1,461 7.30 1,663 8.31 893 4.46 

Aesthetics and other:

Yard 23.22 20.33 18.50 16.68 14.88 13.13 11.43 9.81 16.00 Public 25.94 22.71 20.66 18.63 16.62 14.66 12.77 10.96 17.87 

Total benefits:

Yard: west 30.80 40.21 50.32 57.87 62.98 66.10 67.00 67.36 55.33 

Yard: south 26.71 29.83 34.02 39.07 42.49 45.50 47.03 48.13 39.10 Yard: east 27.87 33.57 40.41 46.86 51.27 54.35 55.56 56.30 45.77 Public 31.23 36.85 43.52 49.66 53.78 56.66 57.70 58.26 48.46 

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. RU = resource unit. a Values are the same for yard and public trees.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

87

Table 10—Annual costs (dollars per tree) at 5-year intervals and 40-year average for a 

representative medium tree (Norway maple)

Costs Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Tree and plantinga:

Yard 35.00 4.38 

Public 28.00 3.50 

Pruning:

Yard 0.23 2.45 2.37 2.30 2.22 6.13 5.91 5.70 3.40 

Public 5.44 6.20 5.88 5.56 5.24 8.20 7.66 7.12 6.52 

Remove and dispose:

Yard 0.27 1.23 1.79 2.31 2.80 3.25 3.66 4.03 2.22 

Public 2.29 1.46 2.13 2.75 3.33 3.87 4.36 4.80 2.72 

Pest and disease

Yard 0.05 0.10 0.15 0.18 0.21 0.24 0.26 0.28 0.17 

Public 0.05 0.09 0.13 0.15 0.18 0.19 0.20 0.21 0.14 

Infrastructure repair:

Yard 0.08 0.14 0.20 0.25 0.30 0.33 0.31 0.39 0.24

Public 0.55 1.02 1.41 1.73 1.97 2.14 2.26 2.32 1.57

Irrigation:

Yard 0 0 0 0 0 0 0 0 0

Public 1.34 0 0 0 0 0 0 0 0.18 

Cleanup:

Yard 0.02 0.04 0.06 0.07 0.09 0.10 0.09 0.11 0.07 

Public 0.16 0.30 0.41 0.50 0.57 0.62 0.66 0.68 0.46 

Liability and legal:

Yard 0 0 0.01 0.01 0.01 0.01 0.01 0.01 0.01 

Public 0.02 0.03 0.04 0.05 0.06 0.07 0.07 0.07 0.05 

Admin./inspect/other:

Yard 0 0 0 0 0 0 0 0 0

Public 1.09 2.01 2.77 3.39 3.86 4.21 4.43 4.54 3.07 

Total costs:

 Yard 35.66 3.97 4.57 5.12 5.62 10.06 10.25 10.52 10.48

Public 38.94 11.12 12.78 14.14 15.21 19.30 19.64 19.75 18.21

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent.

a

Although tree and planting costs occur in year 1, this value was divided by 5 years to derive an average annual cost for the 

first 5-year period.

Table 11—Annual net benefits (dollars per tree) at 5-year intervals and 40-year average for 

a representative medium tree (Norway maple)

Total net benefits Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Yard: west -5 36 46 53 57 56 57 57 45

Yard: south -9 26 29 34 37 35 37 38 29

Yard: east -8 30 36 42 46 44 45 46 35

Public -8 26 31 36 39 37 38 39 30

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. See table 9 for annual benefits and table 

10 for annual costs.
88

GENERAL TECHNICAL REPORT PSW-GTR-206 

Table 12—Annual benefits (dollars per tree) at 5-year intervals and 40-year average for a representative large tree (white ash) Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40 40-year average Benefits/tree RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Cooling (kWh): Yard: west 48 3.90 176 14.42 306 25.10 395 32.42 459 37.63 495 40.55 515 42.20 522 42.83 364 29.88 Yard: south 22 1.81 91 7.43 167 13.69 247 20.25 305 25.03 355 29.08 388 31.80 409 33.54 248 20.33 Yard: east 28 2.32 113 9.23 203 16.62 281 23.01 337 27.63 377 30.87 402 32.93 416 34.11 269 22.09 Public 21 1.71 81 6.65 145 11.85 209 17.13 256 20.96 296 24.27 323 26.49 342 28.06 209 17.14 Heating (therms): Yard: west 1.43 1.67 4.81 5.61 7.66 8.93 9.17 10.69 10.21 11.91 10.31 12.03 10.23 11.93 9.82 11.45 7.95 9.28 Yard: south 0.71 0.83 1.98 2.32 2.67 3.12 3.28 3.83 3.71 4.33 3.82 4.46 3.85 4.49 3.72 4.35 2.97 3.47 Yard: east 1.06 1.24 3.66 4.27 5.87 6.84 7.38 8.61 8.45 9.86 8.76 10.21 8.85 10.33 8.64 10.08 6.58 7.68 Public 1.82 2.12 6.25 7.30 10.24 11.94 12.67 14.78 14.38 16.77 14.77 17.23 14.85 17.32 14.42 16.83 11.17 13.04 Net energy (kWh): Yard: west 90 5.58 317 20.03 531 34.04 664 43.12 758 49.54 797 52.58 814 54.14 810 54.29 598 39.16 Yard: south 43 2.65 149 9.74 245 16.81 343 24.08 414 29.36 467 33.54 501 36.29 518 37.88 335 23.79 Yard: east 59 3.56 220 13.49 375 23.46 497 31.62 585 37.49 633 41.09 661 43.26 669 44.18 462 29.77 Public 74 3.83 264 13.94 445 23.80 580 31.91 677 37.73 729 41.51 758 43.81 765 44.88 537 30.18 Net carbon dioxide (lb): Yard: west 58 0.19 208 0.70 359 1.20 466 1.55 545 1.82 592 1.98 623 2.08 638 2.13 436 1.46 Yard: south 30 0.10 112 0.37 196 0.66 286 0.95 354 1.18 411 1.37 453 1.51 482 1.61 290 0.97 Yard: east 39 0.13 148 0.49 260 0.87 359 1.20 433 1.45 485 1.62 522 1.74 545 1.82 349 1.17 Public 42 0.14 155 0.52 269 0.90 368 1.23 442 1.48 496 1.66 534 1.78 558 1.86 358 1.20 Air pollution (lb)a

:

Ozone uptake 0.052 0.03 0.219 0.11 0.410 0.21 0.622 0.32 0.805 0.41 0.991 0.51 1.155 0.59 1.317 0.67 0.70 0.36 Nitrogen dioxide uptake

+ avoided 0.077 0.04 0.294 0.15 0.519 0.26 0.712 0.36 0.854 0.44 0.958 0.49 1.029 0.52 1.074 0.55 0.69 0.35 

Sulfur dioxide uptake + 

avoided 0.152 0.01 0.588 0.04 1.049 0.06 1.447 0.09 1.735 0.10 1.946 0.12 2.080 0.12 2.160 0.13 1.39 0.08 

Small particulate matter 

uptake + avoided 0.020 0.02 0.112 0.10 0.270 0.25 0.479 0.44 0.681 0.63 0.874 0.80 1.055 0.97 1.227 1.13 0.59 0.54 

Volatile organic 

compounds avoided 0.014 0 0.052 0.01 0.092 0.01 0.127 0.02 0.152 0.02 0.170 0.02 0.181 0.03 0.188 0.03 0.12 0.02 

Biogenic volatile organic 

compounds released 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Total air pollution 

avoided + net uptake 0.315 0.10 1.266 0.41 2.340 0.80 3.387 1.23 4.227 1.60 4.938 1.94 5.500 2.23 5.966 2.50 3.49 1.35 

Hydrology (gal)

Rainfall interception 82 0.41 349 1.75 654 3.27 993 4.96 1,285 6.43 1,582 7.91 1,843 9.22 2,102 10.51 1,111 5.56 

Aesthetics and other:

Yard 11.45 32.79 40.55 39.37 33.51 25.47 16.68 10.19 26.25 Public 12.79 36.62 45.29 43.98 37.43 28.44 18.63 11.38 29.32 

Total benefits:

Yard: west 17.72 55.67 79.85 90.24 92.90 89.87 84.35 79.62 73.78 

Yard: south 14.70 45.05 62.08 70.60 72.08 70.22 65.93 62.70 57.92 Yard: east 15.65 48.93 68.95 78.39 80.47 78.02 73.14 69.21 64.09 Public 17.26 53.24 74.05 83.30 84.67 81.45 75.68 71.14 67.60 

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. RU = resource unit. a Values are the same for yard and public trees.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

89

Table 13—Annual costs (dollars per tree) at 5-year intervals and 40-year average for a 

representative large tree (white ash)

Costs Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Tree and plantinga:

Yard 35.00 4.38 

Public 28.00 3.50 

Pruning:

Yard 0.23 2.45 2.37 2.30 6.34 6.13 5.91 5.70 3.92 

Public 5.44 6.20 5.88 5.56 8.73 8.20 7.66 7.12 6.97 

Remove and dispose:

Yard 0.08 1.14 1.78 2.37 2.92 3.43 3.91 4.37 2.31 

Public 0.26 1.36 2.12 2.83 3.48 4.09 4.66 5.20 2.77 

Pest and disease

Yard 0.04 0.10 0.15 0.19 0.22 0.25 0.28 0.30 0.18 

Public 0.04 0.09 0.13 0.16 0.18 0.20 0.22 0.22 0.14 

Infrastructure repair:

Yard 0.06 0.13 0.20 0.26 0.31 0.35 0.39 0.42 0.24

Public 0.41 0.95 1.41 1.77 2.06 2.27 2.42 2.51 1.60

Irrigation:

Yard 0 0 0 0 0 0 0 0 0 

Public 1.34 0 0 0 0 0 0 0 0.18 

Cleanup:

Yard 0.02 0.04 0.06 0.08 0.09 0.10 0.11 0.12 0.07 

Public 0.12 0.28 0.41 0.52 0.60 0.66 0.70 0.73 0.47 

Liability and legal:

Yard 0 0 0.01 0.01 0.01 0.01 0.01 0.01 0.01 

Public 0.01 0.03 0.04 0.06 0.06 0.07 0.08 0.08 0.05 

Admin. and other:

Yard 0 0 0 0 0 0 0 0 0

Public 0.81 1.87 2.76 3.48 4.03 4.45 4.74 4.92 3.14 

Total costs:

 Yard 35.43 3.86 4.57 5.20 9.90 10.28 10.62 10.92 11.11

Public 36.43 10.78 12.76 14.37 19.15 19.94 20.47 20.79 18.81

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent.

a

Although tree and planting costs occur in year 1, this value was divided by 5 years to derive an average annual cost for the 

first 5-year period.

Table 14—Annual net benefits (dollars per tree) at 5-year intervals and 40-year average 

for a representative large tree (white ash)

Total net benefits Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Yard: west -18 52 75 85 83 80 74 69 63

Yard: south -21 41 58 65 62 60 55 52 47

Yard: east -20 45 64 73 71 68 63 58 53

Public -19 42 61 69 66 62 55 50 49

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. See table 12 for annual benefits and 

table 13 for annual costs.
90

GENERAL TECHNICAL REPORT PSW-GTR-206 

Table 15—Annual benefits (dollars per tree) at 5-year intervals and 40-year average for a representative conifer tree (blue spruce) Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40 40-year average Benefits/tree RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value RU Value Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Dollars Cooling (kWh): Yard 17 1.39 40 3.28 57 4.67 71 5.82 80 6.56 87 7.13 90 7.38 91 7.46 67 5.46 Public 17 1.39 40 3.28 57 4.67 71 5.82 80 6.56 87 7.13 90 7.38 91 7.46 67 5.46 Heating (therms): Yard 2.57 3.00 4.99 5.82 6.60 7.70 7.69 8.97 8.28 9.67 8.75 10.21 8.77 10.23 8.71 10.16 7.05 8.22 Public 2.57 3.00 4.99 5.82 6.60 7.70 7.69 8.97 8.28 9.67 8.75 10.21 8.77 10.23 8.71 10.16 7.05 8.22 Net energy (kWh): Yard 92 4.39 186 9.10 250 12.37 297 14.79 323 16.22 344 17.34 347 17.61 346 17.62 273 13.68 Public 92 4.39 186 9.10 250 12.37 297 14.79 323 16.22 344 17.34 347 17.61 346 17.62 273 13.68 Net carbon dioxide (lb): Yard 46 0.15 97 0.32 134 0.45 161 0.54 178 0.59 191 0.64 194 0.65 195 0.65 150 0.50 Public 46 0.15 97 0.32 134 0.45 161 0.54 178 0.59 191 0.64 194 0.65 195 0.65 150 0.50 Air pollution (lb)a Ozone uptake 0.042 0.02 0.108 0.06 0.161 0.08 0.213 0.11 0.252 0.13 0.292 0.15 0.322 0.16 0.352 0.18 0.22 0.11 Nitrogen dioxide uptake + avoided 0.064 0.03 0.142 0.07 0.197 0.10 0.243 0.12 0.271 0.14 0.294 0.15 0.303 0.15 0.308 0.16 0.23 0.12 Sulfur dioxide uptake + avoided 0.087 0.01 0.204 0.01 0.290 0.02 0.365 0.02 0.410 0.02 0.447 0.03 0.460 0.03 0.467 0.03 0.34 0.02 Small particulate matter uptake + avoided 0.014 0.01 0.050 0.05 0.101 0.09 0.163 0.15 0.218 0.20 0.268 0.25 0.269 0.25 0.270 0.25 0.17 0.16 Volatile organic compounds avoided 0.009 0.00 0.020 0.00 0.028 0.00 0.035 0.00 0.039 0.01 0.043 0.01 0.044 0.01 0.044 0.01 0.03 0.01 Biogenic volatile organic compounds released -0.057 -0.01 -0.223 -0.03 -0.601 -0.08 -1.344 -0.19 -2.363 -0.33 -3.656 -0.51 -3.656 -0.51 -3.656 -0.51 -1.94 -0.27 Total air pollution avoided + net uptake 0.159 0.06 0.301 0.16 0.176 0.21 -0.325 0.21 -1.173 0.17 -2.312 0.08 -2.258 0.09 -2.215 0.12 -0.96 0.14 Hydrology (gal) Rainfall interception 262 1.31 671 3.36 1,014 5.07 1,390 6.95 1,681 8.41 1,972 9.86 2,218 11.09 2,463 12.32 1,459 7.30 Aesthetics and other: Yard 10.63 11.52 11.55 11.12 10.51 9.82 9.11 8.39 10.33 Public 11.87 12.87 12.90 12.42 11.74 10.97 10.18 9.37 11.54 Total benefits: Yard 16.54 24.46 29.65 33.61 35.90 37.74 38.55 39.10 31.95 Public 17.78 25.81 31.00 34.91 37.13 38.89 39.62 40.08 33.15 Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. RU = resource unit. a Values are the same for yard and public trees.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

91

Table 16—Annual costs (dollars per tree) at 5-year intervals and 40-year average for a 

representative conifer tree (blue spruce)

Costs Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Tree and plantinga:

Yard 35.00 4.38 

Public 28.00 3.50 

Pruning:

Yard 0.02 0.02 0.24 0.23 0.22 0.21 0.21 0.57 0.17

Public 0.54 0.33 0.59 0.56 0.52 0.49 0.46 0.71 0.50

Remove and dispose:

Yard 0.87 1.24 1.75 2.19 2.57 2.92 3.23 3.52 2.07 

Public 2.24 1.48 2.09 2.61 3.07 3.48 3.85 4.19 2.51 

Pest and disease

Yard 0.05 0.10 0.14 0.17 0.20 0.22 0.23 0.24 0.16 

Public 0.05 0.09 0.12 0.15 0.16 0.17 0.18 0.18 0.13 

Infrastructure repair:

Yard 0.07 0.15 0.20 0.24 0.27 0.30 0.32 0.34 0.22

Public 0.54 1.03 1.38 1.64 1.81 1.93 1.99 2.02 1.45

Irrigation:

Yard 0 0 0 0 0 0 0 0 0 

Public 1.34 0 0 0 0 0 0 0 0.18 

Cleanup:

Yard 0.02 0.04 0.06 0.07 0.08 0.09 0.09 0.10 0.06 

Public 0.16 0.30 0.40 0.48 0.53 0.56 0.58 0.59 0.42 

Liability and legal:

Yard 0 0 0.01 0.01 0.01 0.01 0.01 0.01 0.01 

Public 0.02 0.03 0.04 0.05 0.06 0.06 0.06 0.06 0.05 

Admin./inspect/other:

Yard 0 0 0 0 0 0 0 0 0

Public 1.07 1.07 2.72 3.21 3.55 3.78 3.91 3.96 2.84 

Total costs:

 Yard 36.04 1.55 2.40 2.91 3.36 3.75 4.09 4.77 7.07

Public 33.96 4.33 7.35 8.68 9.70 10.47 11.04 11.72 11.57

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. RU = resource unit. 

a

Although tree and planting costs occur in year 1, this value was divided by 5 years to derive an average annual cost for the 

first 5-year period.

Table 17—Annual net benefits (dollars per tree) at 5-year intervals and 40-year average 

for a representative conifer tree (blue spruce)

Total net benefits Year 5 Year 10 Year 15 Year 20 Year 25 Year 30 Year 35 Year 40

40-year 

average

Dollars

Yard -19 23 27 31 33 34 34 34 25

Public -16 21 24 26 27 28 29 28 22

Note: Annual values incorporate effects of tree loss. We assume that 13 percent of trees planted die during the first 5 years 

and 30.1 percent during the remaining 35 years for a total mortality of 43.1 percent. See table 15 for annual benefits and 

table 16 for annual costs.

Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

93

Appendix 3: Procedures for Estimating Benefits and Costs

Approach

Pricing Benefits and Costs

In this study, annual benefits and costs over a 40-year planning horizon were 

estimated for newly planted trees in three residential yard locations (east, south, 

and west of the dwelling unit) and a public streetside or park location. Trees in 

these hypothetical locations are called “yard” and “public” trees, respectively. 

Prices were assigned to each cost (e.g., planting, pruning, removal, irrigation, 

infrastructure repair, liability) and benefit (e.g., heating/cooling, energy savings, 

air-pollution reduction, stormwater-runoff reduction) through direct estimation 

and implied valuation of benefits as environmental externalities. This approach 

made it possible to estimate the net benefits of plantings in “typical” locations 

with “typical” tree species.

To account for differences in the mature size and growth rates of different tree 

species, we report results for a small (crabapple), medium (Norway maple), and 

large (white ash) deciduous tree and for a conifer (blue spruce) (see “Common and 

Scientific Names” section). Results are reported for 5-year intervals for 40 years.

Mature tree height is frequently used to characterize small, medium, and large 

species because matching tree height to available overhead space is an important 

design consideration. However, in this analysis, leaf surface area (LSA) and crown 

diameter were also used to characterize mature tree size. These additional measurements are useful indicators for many functional benefits of trees that relate to 

leaf-atmosphere processes (e.g., interception, transpiration, photosynthesis). Tree 

growth rates, dimensions, and LSA estimates are based on tree growth modeling.

Growth Modeling 

Growth models are based on data collected in Boise, Idaho. The city’s Parks and 

Recreation Department provided an inventory of Boise’s municipal trees that 

included 23,262 trees. 

Tree-growth models developed from Boise data were used as the basis for 

modeling tree growth for this report. Using Boise’s tree inventory, we measured a 

stratified random sample of 20 of the most common tree species to establish relations between tree age, size, leaf area, and biomass. The species were as follows:

• Norway maple (Acer platanoides)

• Silver maple (Acer saccharinum)

• Sugar maple (Acer saccharum)
94

GENERAL TECHNICAL REPORT PSW-GTR-206 

• Northern catalpa (Catalpa speciosa)

• Hawthorn (Crataegus sp.)

• White ash (Fraxinus americana)

• Green ash (Fraxinus pennsylvanica)

• Honeylocust (Gleditsia triacanthos)

• Black walnut (Juglans nigra)

• Sweetgum (Liquidambar styraciflua)

• Crabapple (Malus sp.)

• Blue spruce (Picea pungens)

• Scotch pine (Pinus sylvestris)

• London planetree (Platanus hybrida)

• American sycamore (Platanus occidentalis)

• Callery pear (Pyrus calleryana)

• Northern red oak (Quercus rubra)

• Black locust (Robinia pseudoacacia)

• American linden (Tilia americana)

• Siberian elm (Ulmus pumila)

For the growth models, information spanning the life cycle of predominant tree 

species was collected. The inventory was stratified into the following nine diameter-at-breast-height (d.b.h.) classes:

• 0 to 2.9 in

• 3.0 to 5.9 in

• 6.0 to 11.9 in

• 12.0 to 17.9 in

• 18.0 to 23.9 in

• 24.0 to 29.9 in

• 30.0 to 35.9 in

• 36.0 to 41.9 in

• ≥ 42.0 in

Thirty to sixty trees of each species were randomly selected for surveying, 

along with an equal number of alternative trees. Tree measurements included d.b.h. 

(to nearest 0.1 cm [0.04 in] by sonar measuring device), tree crown height, and bole 

height (to nearest 0.5 m [1.6 ft] by clinometer), crown diameter in two directions 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

95

(parallel and perpendicular to nearest street to nearest 0.5 m [1.6 ft] by sonar 

measuring device), tree condition, and location. Replacement trees were sampled 

when trees from the original sample population could not be located. Tree age was 

determined by street-tree managers. Fieldwork was conducted in August and September 2005.

Crown volume and leaf area were estimated from computer processing of 

tree-crown images obtained with a digital camera. The method has shown greater 

accuracy than other techniques (± 20 percent of actual leaf area) in estimating 

crown volume and leaf area of open-grown trees (Peper and McPherson 2003).

Linear regression was used to fit predictive models with d.b.h. as a function 

of age for each of the 20 sampled species. Predictions of LSA, crown diameter, 

and height metrics were modeled as a function of d.b.h. by using best-fit models. 

After inspecting the growth curves for each species, we selected the typical small, 

medium, and large tree species for this report.

Reporting Results

Results are reported in terms of annual values per tree planted. However, to make 

these calculations realistic, mortality rates are included. Based on our survey of 

regional municipal foresters and commercial arborists, this analysis assumed that 

43 percent of the hypothetical planted trees died over the 40-year period. Annual 

mortality rates were 2.6 percent for the first 5 years, and 0.85 percent per year after 

that. The accounting approach “grows” trees in different locations and uses computer simulation to directly calculate the annual flow of benefits and costs as trees 

mature and die (McPherson 1992).

Benefits and costs are directly connected with tree-size variables such as trunk 

d.b.h., tree canopy cover, and LSA. For instance, pruning and removal costs usually 

increase with tree size, expressed as d.b.h. For some parameters, such as sidewalk 

repair, costs are negligible for young trees but increase relatively rapidly as tree 

roots grow large enough to heave pavement. For other parameters, such as air-pollutant uptake and rainfall interception, benefits are related to tree canopy cover and 

leaf area.

Most benefits occur on an annual basis, but some costs are periodic. For 

instance, street trees may be pruned on regular cycles but are removed in a less 

regular fashion (e.g., when they pose a hazard or soon after they die). In this analysis, most costs and benefits are reported for the year in which they occur. However, 

periodic costs such as pruning, pest and disease control, and infrastructure repair 

are presented on an average annual basis. Although spreading one-time costs over 

each year of a maintenance cycle does not alter the 40-year nominal expenditure, it 

can lead to inaccuracies if future costs are discounted to the present.
96

GENERAL TECHNICAL REPORT PSW-GTR-206 

Benefit and Cost Valuation

Source of cost estimates—

Frequency and costs of tree management were estimated based on surveys with 

municipal foresters from Boise, Lewiston, Nampa, Payette, and Caldwell, Idaho, 

and Carson City, Nevada. Several arborists from Boise and Meridian, Idaho, 

provided information on tree management costs on residential properties.

Monetizing benefits—

To monetize effects of trees on energy use, we take the perspective of a residential 

customer by using retail electricity and natural-gas prices for utilities serving the 

Temperate Interior West, including Boise, Reno, Nevada, and Yakima, Washington. 

The retail price of energy reflects a full accounting of costs as paid by the end user, 

such as the utility costs of power generation, transmission, distribution, administration, marketing, and profit. This perspective aligns with our modeling method, 

which calculates energy effects of trees based on differences among consumers in 

heating and air conditioning equipment types, saturations, building construction 

types, and base loads. 

The preferred way to value air quality benefits from trees is to first determine 

the costs of damages to human health from polluted air, then calculate the value of 

avoided costs because trees are cleaning the air. Economic valuation of damages 

to human health usually uses information on willingness to pay to avoid damages 

obtained via interviews or direct estimates of the monetary costs of damages (e.g., 

alleviating headaches, extending life). Empirical correlations developed by Wang 

and Santini (1995) reviewed 5 studies and 15 sets of regional cost data to relate perton costs of various pollutant emissions to regional ambient air quality measurements and population size. We use their damage-based estimates unless the values 

are negative, in which case we use their control-cost-based estimates. 

Calculating Benefits

Calculating Energy Benefits

The prototypical building used as a basis for the simulations was typical of post1980 construction practices and represents approximately one-third of the total 

single-family residential housing stock in the Temperate Interior West region. The 

house was a one-story, wood-frame, slab-on-grade building with a conditioned 

floor area of 2,070 ft2, window area (double-glazed) of 263 ft2, and wall and 

ceiling insulation of R13 and R31, respectively. The central cooling system had a 

seasonal energy efficiency ratio (SEER) of 10, and the natural-gas furnace had 

an annual fuel utilization efficiency (AFUE) of 78 percent. Building footprints 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

97

were square, reflecting average impacts for a large number of buildings (McPherson 

and Simpson 1999). Buildings were simulated with 1.5-ft overhangs. Blinds had a 

visual density of 37 percent and were assumed to be closed when the air conditioner 

was operating. Summer thermostat settings were 78 °F; winter settings were 68 °F 

during the day and 60 °F at night. Because the prototype building was larger, but 

more energy efficient, than most other construction types, our projected energy 

savings can be considered similar to those for older, less thermally efficient, but 

smaller buildings. The energy simulations relied on typical meteorological data 

from Boise (Marion and Urban 1995).

Calculating energy savings—

The dollar value of energy savings was based on regional average residential 

electricity and natural-gas prices of $0.082/kWh and $1.17/therm (Idaho Power 

Company 2006, Intermountain Gas Company 2006). Homes were assumed to have 

central air conditioning and natural-gas heating.

Calculating shade effects—

Residential yard trees were within 60 ft of homes so as to directly shade walls and 

windows. Shade effects of these trees on building energy use were simulated for 

small, medium, and large trees at three tree-to-building distances, following methods outlined by McPherson and Simpson (1999). Results of shade effects for each 

tree were averaged over distance and weighted by occurrence within each of three 

distance classes: 28 percent at 10 to 20 ft (3 to 6 m), 68 percent at 20 to 40 ft (6 to 

12 m), and 4 percent at 40 to 60 ft (12 to 18 m) (McPherson and Simpson 1999).

The small tree (crabapple) had visual densities of 85 percent during summer 

and 15 percent during winter, the medium tree (Norway maple) had visual densities 

of 69 percent during summer and 12 percent during winter, and the large tree (white 

ash) had visual densities of 78 percent during summer and 17 percent during winter. 

The conifer (blue spruce) had a visual density of 20 percent.

Leaf-off values for use in calculating winter shade were based on published 

values where available (Hammond et al. 1980, McPherson 1984). Foliation 

periods for deciduous trees were obtained from the literature (Hammond et al. 

1980, McPherson 1984) and adjusted for Boise based on consultation with the 

city forester (Jorgenson 2006). The foliation periods of the trees were as follows: 

small tree 21 May–14 November, medium tree 21 May–7 November, large tree 21 

May–20 October.

Results are reported for trees shading east-, south-, and west-facing surfaces. 

Our results for public trees are conservative in that we assumed that they do not 

provide shading benefits. For example, in Modesto, California, 15 percent of total 
98

GENERAL TECHNICAL REPORT PSW-GTR-206 

annual dollar energy savings from street trees was due to shade and 85 percent due 

to climate effects (McPherson et al. 1999a).

Calculating climate effects—

In addition to localized shade effects, which were assumed to accrue only to 

residential yard trees, lowered air temperatures and windspeeds from increased 

neighborhood tree cover (referred to as climate effects) produced a net decrease 

in demand for winter heating and summer cooling (reduced windspeeds by themselves may increase or decrease cooling demand, depending on the circumstances). 

Climate effects on energy use, air temperature, and windspeed, as a function of 

neighborhood canopy cover, were estimated from published values (McPherson and 

Simpson 1999). Existing tree canopy plus building cover was 26 percent based on 

estimates of urban tree cover for Idaho (Nowak and Crane 2002). Canopy cover was 

calculated to increase by 4.3 percent, 6.6 percent, 8.8 percent, and 3.0 percent for 

20-year-old small, medium, and large deciduous and coniferous trees, respectively, 

based on an effective lot size (actual lot size plus a portion of adjacent street and 

other rights-of-way) of 10,000 ft2, and one tree on average was assumed per lot. 

Climate effects were estimated by simulating effects of wind reductions and airtemperature reductions on energy use. Climate effects accrued for both public and 

yard trees.

Calculating windbreak effects—

Trees near buildings result in additional windspeed reductions beyond those from 

the aggregate effects of trees throughout the neighborhood. This leads to a small 

additional reduction in annual heating energy use of about 0.5 percent per tree for 

this region (McPherson and Simpson 1999). Yard and public conifer trees were 

assumed to be windbreaks, and therefore located where they did not increase 

heating loads by obstructing winter sun. Windbreak effects were not attributed to 

deciduous trees, as their crowns are leafless and above the ground, and therefore do 

not block winds near ground level.

Atmospheric Carbon Dioxide Reduction

Calculating reduction in CO2 emissions from power plants—

Conserving energy in buildings can reduce carbon dioxide (CO2) emissions from 

power plants. Emission reductions were calculated as the product of energy savings 

for heating and cooling with CO2 emission factors (table 18) based on data for 

Idaho Power Company, the local utility company in Boise, where the average fuel 

mix consists almost entirely of hydroelectric (99.9 percent) power (U.S. EPA 2003). 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

99

The value of $6.68 per ton CO2 reduction (table 18) was based on the average value 

given by Pearce (2003).

Calculating carbon storage—

Sequestration, the net rate of CO2 storage in above- and belowground biomass over 

the course of one growing season, was calculated from tree height and d.b.h. data 

with biomass equations (Pillsbury et al. 1998). Volume estimates were converted 

to green- and dry-weight estimates (Markwardt 1930) and divided by 78 percent to 

incorporate root biomass. Dry-weight biomass was converted to carbon (50 percent) 

and these values were converted to CO2. The amount of CO2 sequestered each year 

is the annual increment of CO2 stored as trees increase their biomass.

Calculating CO2 released by power equipment—

Tree-related emissions of CO2, based on gasoline and diesel fuel consumption 

during tree care in our survey cities, were calculated by using the value 0.89 lbs 

of CO2 per in d.b.h. (Jorgenson 2006). This amount may overestimate CO2 release 

associated with less intensively maintained residential yard trees.

Calculating CO2 released during decomposition—

To calculate CO2 released through decomposition of dead woody biomass, we 

conservatively estimated that dead trees were removed and mulched in the year 

that death occurred, and that 80 percent of their stored carbon was released to the 

atmosphere as CO2 in the same year (McPherson and Simpson 1999).

Calculating reduction in air pollutant emissions—

Reductions in building energy use also result in reduced emission of air pollutants 

Table 18—Emissions factors and implied values for carbon dioxide and criteria 

air pollutants

Emission factor Electricitya Natural gasb Implied valuec

Pounds per megawatt hour Pounds per therm Dollars per pound

Carbon dioxide 746 11.8 0.00334

Nitrogen dioxide 1.443 0.01020 0.51

Sulfur dioxide 0.988 0.00006 0.06

Small particulate matter 0.500 0.00075 0.92

Volatile organic compounds 0.460 0.00054 0.14

a U.S. EPA 2003, except Ottinger et al. 1990 for volatile organic compounds.

b U.S. EPA 1998.

c Carbon dioxide from Pearce 2003. Value for others based on methods of Wang and Santini (1995) using 

emissions concentrations from U.S. Environmental Protection Agency (2003) and population estimates from the 

U.S. Census Bureau (2006).
100

GENERAL TECHNICAL REPORT PSW-GTR-206 

from power plants and space-heating equipment. Volatile organic hydrocarbons 

(VOCs) and nitrogen dioxide (NO2)—both precursors of ozone formation—as 

well as sulfur dioxide (SO2) and particulate matter <10 microns in diameter (PM10) 

were considered. Changes in average annual emissions and their monetary values 

were calculated in the same way as for CO2, with utility-specific emissions factors 

for electricity and heating fuels (Ottinger et al. 1990, U.S. EPA 1998). The price 

of emissions savings was derived from models that calculate the marginal cost of 

controlling different pollutants to meet air quality standards (Wang and Santini 

1995). Emissions concentrations were obtained from U.S. EPA (2003) (table 18), 

and population estimates from the U.S. Census Bureau (2006).

Calculating pollutant uptake by trees—

Trees also remove pollutants from the atmosphere. The modeling method we 

applied was developed by Scott et al. (1998). It calculates hourly pollutant dry deposition per tree expressed as the product of deposition velocity (Vd = 1/[Ra + Rb + Rc]), 

pollutant concentration (C), canopy-projection area (CP), and a time step, where 

Ra, Rb and Rc are aerodynamic, boundary layer, and stomatal resistances. Hourly 

deposition velocities for each pollutant were calculated during the growing season 

by using estimates for the resistances (Ra + Rb + Rc ) for each hour throughout the 

year. Hourly concentrations for O3 and PM10 for Boise and NO2 for Mountain Home, 

Idaho, were obtained from the Environmental Protection Agency (U.S. EPA 2006), 

and hourly meteorological data (i.e., air temperature, windspeed, solar radiation) 

were obtained from the Pacific Northwest Cooperative Agricultural Weather Network (Agrimet 2006). The year 2003 was chosen because it most closely approximated long-term, regional climate records. To set a value for pollutant uptake by 

trees, we used the procedure described above for emissions reductions (table 18). 

The monetary value for NO2 was used for ozone.

Estimating BVOC emissions from trees—

Annual emissions for biogenic volatile organic compounds (BVOCs) were estimated for the four tree species by using the algorithms of Guenther et al. (1991, 

1993). Annual emissions were simulated during the growing season over 40 years. 

The emission of carbon as isoprene was expressed as a product of the base emission 

rate (μg C per g dry foliar biomass per h), adjusted for sunlight and temperature 

and the amount of dry, foliar biomass present in the tree. Monoterpene emissions 

were estimated by using a base emission rate adjusted for temperature. The base 

emission rates for the four species were based on values reported in the literature 

(Benjamin and Winer 1998). Hourly emissions were summed to get monthly and 

annual emissions.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

101

Annual dry foliar biomass was derived from field data collected in Boise, 

Idaho, during the late summer of 2005. The amount of foliar biomass present 

for each year of the simulated tree’s life was unique for each species. Hourly air 

temperature and solar radiation data for 2003 described in the pollutant uptake 

section were used as model inputs.

Calculating net air quality benefits—

Net air quality benefits were calculated by subtracting the costs associated with 

BVOC emissions from benefits associated with pollutant uptake and avoided 

power plant emissions. The ozone-reduction benefit from lowering summertime air 

temperatures, thereby reducing hydrocarbon emissions from anthropogenic and 

biogenic sources, was estimated as a function of canopy cover following McPherson and Simpson (1999). They used peak summer air temperature reductions of 0.4 

°F for each percentage increase in canopy cover. Hourly changes in air temperature were calculated by reducing this peak air temperature at every hour based on 

hourly maximum and minimum temperature for that day, scaled by magnitude of 

maximum total global solar radiation for each day relative to the maximum value 

for the year.

Stormwater Benefits

Estimating rainfall interception by tree canopies—

A numerical simulation model was used to estimate annual rainfall interception 

(Xiao et al. 2000). The interception model accounted for water intercepted by the 

tree, as well as throughfall and stem flow. Intercepted water is stored temporarily 

on canopy leaf and bark surfaces. Rainwater evaporates or drips from leaf surfaces 

and flows down the stem surface to the ground. Tree-canopy parameters that affect 

interception include species, leaf and stem surface areas, shade coefficients (visual 

density of the crown), foliation periods, and tree dimensions (e.g., tree height, 

crown height, crown diameter, and d.b.h.). Tree-height data were used to estimate 

windspeed at different heights above the ground and resulting rates of evaporation.

The volume of water stored in the tree crown was calculated from crown-projection area (area under tree dripline), leaf area indices (LAI, the ratio of LSA to 

crown projection area), and the depth of water captured by the canopy surface. Gap 

fractions, foliation periods, and tree surface saturation storage capacity influence 

the amount of projected throughfall. Tree surface saturation was 1.0 mm (0.04 in) 

for all trees. 

Hourly meteorological and rainfall data for 2004 at the AgriMet Station (BOII) 

(The Pacific Northwest Cooperative Agricultural Weather Network, station‘s 

latitude 43° 36’ 01” N, longitude 116° 10’ 37” W, elevation 2,720 feet) in Boise, 
102

GENERAL TECHNICAL REPORT PSW-GTR-206 

Idaho, were used in this simulation. The year 2004 was chosen because, although 

the overall amount of rainfall was higher, it most closely approximated the monthly 

distribution of the long-term average rainfall. Annual precipitation at BOII during 

2004 was 16.4 in. Storm events less than 0.1 in were assumed not to produce runoff 

and were dropped from the analysis. More complete descriptions of the interception 

model can be found in Xiao et al. (1998, 2000).

Calculating water quality protection and flood control benefit—

The benefits that result from reduced peak runoff include reduced property damage 

from flooding and reduced loss of soil and habitat from erosion and sediment flow. 

Reduced runoff also results in improved water quality in streams, lakes, and rivers. 

This can translate into improved aquatic habitats, less human illness owing to 

contact with contaminated water and reduced stormwater treatment costs. 

According to Johanna Bell (2006), Boise spends approximately $1.97 million 

annually on operations, maintenance, and improvements to its stormwater management system (Bell 2006). To calculate annual runoff we assigned curve numbers for 

each land use (USDA SCS 1986). Land use percentages were obtained from the city 

geographic information system database (Wing 2006). We calculated runoff depth 

for each land use and found the citywide total to be 1,138 acre-feet. Given Boise’s 

area of 68.1 mi2 (176.4 km2), the total annual runoff was 419.9 million gal. The 

annual stormwater control cost ($1.97 million/419.9 million gal) was estimated to be 

$0.005 per gallon of runoff. 

Aesthetic and Other Benefits

Many benefits attributed to urban trees are difficult to translate into economic 

terms. Beautification, privacy, wildlife habitat, shade that increases human comfort, 

sense of place and well-being are services that are difficult to price. However, the 

value of some of these benefits may be captured in the property values of the land 

on which trees stand.

To estimate the value of these “other” benefits, we applied results of research 

that compared differences in sales prices of houses to statistically quantify the 

difference associated with trees. All else being equal, the difference in sales price 

reflects the willingness of buyers to pay for the benefits and costs associated with 

trees. This approach has the virtue of capturing in the sales price both the benefits 

and costs of trees as perceived by the buyers. Limitations to this approach include 

difficulty determining the value of individual trees on a property, the need to 

extrapolate results from studies done years ago, and the need to extrapolate results 

from front-yard trees on residential properties to trees in other locations (e.g., back 

yards, streets, parks, and nonresidential land).
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

103

Anderson and Cordell (1988) surveyed 844 single-family residences in Athens, 

Georgia, and found that each large front-yard tree was associated with a 0.88-percent increase in the average home sales price. This percentage of sales price was 

used as an indicator of the additional value a resident in the Temperate Interior 

West region would gain from selling a home with a large tree.

We used the average median home price for Boise ($155,500) as our starting 

point. Therefore, the value of a large tree that added 0.88 percent to the sales price 

of such a home was $1,322. To estimate annual benefits, the total added value was 

divided by the LSA of a 30-year-old white ash ($1,322 per 5,179 ft2) to yield the 

base value of LSA, $0.255 per ft2. This value was multiplied by the amount of leaf 

surface area added to the tree during 1 year of growth.

Additionally, not all street trees are as effective as front-yard trees in increasing 

property values. For example, trees adjacent to multifamily housing units will not 

increase the property value at the same rate as trees in front of single-family homes. 

Therefore, a citywide street tree reduction factor (0.93) was applied to prorate 

trees’ value based on the assumption that trees adjacent to different land uses 

make different contributions to property sales prices. For this analysis, the street 

reduction factor reflects the distribution of street trees in Boise by land use. Reduction factors were single-home residential (100 percent), multihome residential (70 

percent), small commercial (66 percent), industrial/institutional/large commercial 

(40 percent), park/vacant/other (40 percent) (Gonzales 2004, McPherson 2001).

Calculating the aesthetic and other benefits of residential yard trees—

To calculate the base value for a large tree on private residential property we 

assumed that a 30-year-old white ash in the front yard increased the property sales 

price by $1,322. Approximately 75 percent of all yard trees, however, are in back 

yards (Richards et al. 1984). Lacking specific research findings, it was assumed 

that back-yard trees had 75 percent of the impact on “curb appeal” and sales price 

compared to front-yard trees. The average annual aesthetic and other benefits for a 

tree on private property were, therefore, estimated as $0.19 per ft2 LSA. To estimate 

annual benefits, this value was multiplied by the amount of leaf surface area added 

to the tree during 1 year of growth.

Calculating the aesthetic value of a public tree—

The base value of street trees was calculated in the same way as yard trees. However, because street trees may be adjacent to land with little resale potential, an 

adjusted value was calculated. An analysis of street trees in Modesto, California, 

sampled from aerial photographs (sample size 8 percent of street trees), found 

that 15 percent were located adjacent to nonresidential or commercial property 
104

GENERAL TECHNICAL REPORT PSW-GTR-206 

(McPherson et al. 1999a). We assumed that 33 percent of these trees—or 5 percent 

of the entire street-tree population—produced no benefits associated with property 

value increases.

Although the impact of parks on real estate values has been reported (Hammer et al. 1974, Schroeder 1982, Tyrvainen 1999), to our knowledge, the onsite 

and external benefits of park trees alone have not been isolated (More et al. 1988). 

After reviewing the literature and recognizing an absence of data, we made the 

conservative estimate that park trees had half the impact on property prices of 

street trees. 

Given these assumptions, typical large street and park trees were estimated to 

increase property values by $0.24 and $0.13 per ft2 LSA, respectively. Assuming 

that 80 percent of all municipal trees were on streets and 20 percent in parks, a 

weighted average benefit of $0.217/ft2 LSA was calculated for each tree.

Calculating Costs

Tree management costs were estimated based on surveys with municipal foresters from Boise, Lewiston, Nampa, Payette, and Caldwell, Idaho, and Carson City, 

Nevada. In addition, several commercial arborists from Boise and Meridian, Idaho, 

provided information on tree management costs on residential properties.

Planting

Planting costs include the cost of the tree and the cost for planting, staking, and 

mulching the tree. Based on our survey of Temperate Interior West municipal and 

commercial arborists, planting costs ranged widely from $65 for a 10-gal tree to 

$350 for a 2-in tree. In this analysis we assumed that a 2-in yard tree was planted at 

a cost of $175. The cost for planting a 1.5-in public tree was $140.

Pruning

Pruning costs for public trees—

After studying data from municipal forestry programs and their contractors, we 

assumed that young public trees were inspected and pruned once every 4 years 

during the first 5 years after planting at a cost of $25 per tree. After this training 

period, inspection and pruning occurred once every 10 years. Pruning for small 

trees (< 20 ft tall) cost $40 per tree. More expensive equipment and more time was 

required to prune medium ($75 per tree) and large trees ($125 per tree). After factoring in pruning frequency, annualized costs were $6.24, $4, $7.50, and $12.50 per 

tree for public young, small, medium, and large trees, respectively. Conifers require 

pruning much less frequently; the average annualized cost was $3.23.
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

105

Pruning costs for yard trees—

Based on findings from our survey of commercial arborists in the Temperate Interior West region, pruning cycles for yard trees were about the same as public trees, 

but only about 20 percent of all private trees were professionally pruned (contract 

rate), although the number of professionally pruned trees grows as the trees grow. 

We assumed that professionals are paid to prune all large trees, 60 percent of the 

medium trees, and only 6 percent of the small and young trees and conifers (Summit and McPherson 1998). Using these contract rates, along with average pruning 

prices ($40, $60, $175, and $300 for young, small, medium, and large trees, respectively), the average annual costs for pruning a yard tree were $0.24, $0.28, $2.63, 

and $7.50 for young, small, medium, and large trees, respectively. The annualized 

cost for pruning conifers was $0.16.

Tree and Stump Removal

The costs for tree removal and disposal were $20 per in d.b.h. for public trees, and 

$25 per in d.b.h. for yard trees. Stump removal costs were $7 per in d.b.h. for public 

trees and $9 per in d.b.h. for yard trees. Therefore, total costs for removal and 

disposal of trees and stumps were $27 per in d.b.h. for public trees, and $34 per in 

d.b.h. for yard trees. Removal costs of trees under 3 inches in diameter were $10 for 

yard and public trees.

Pest and Disease Control

Pest and disease control measures in the Temperate Interior West are minimal, with 

cities spending only about $0.16 per tree per year. Because of lack of data from the 

residential arborists surveys, we used the same value for yard trees.

Irrigation Costs

Costs for watering during the critical 5-year establishment period were estimated 

at $1.48 for public trees per tree per year, mainly for the labor costs involved in 

visiting the trees with a water truck or other time-intensive method. Beyond the 

establishment period, it is assumed that trees have been planted into irrigated 

landscapes and therefore the cost of additional water for the trees is negligible. No 

costs for irrigating yard trees were included because these were also assumed to 

be planted in irrigated landscapes where the cost of additional water is negligible 

and the additional labor involved for extra watering during the first 5 years by the 

resident was also considered negligible.

Other Costs for Public and Yard Trees

Other costs associated with the management of trees include expenditures for infrastructure repair/root pruning, leaf-litter cleanup, and inspection/administration. 
106

GENERAL TECHNICAL REPORT PSW-GTR-206 

Infrastructure conflict costs—

As trees and sidewalks age, roots can cause damage to sidewalks, curbs, paving, 

and sewer lines. Sidewalk repair is typically one of the largest expenses for public 

trees (McPherson and Peper 1995). Infrastructure-related expenditures for public 

trees in Temperate Interior West communities were approximately $2.23 per tree 

on an annual basis. Roots from most trees in yards do not damage sidewalks and 

sewers. Therefore, the cost for yard trees was estimated to be only 10 percent of the 

cost for public trees.

Litter and storm cleanup costs—

The average annual cost per tree for litter cleanup (i.e., street sweeping, stormdamage cleanup) was $0.65 per tree ($0.057 per in d.b.h.). This value was based 

on average annual litter cleanup costs and storm cleanup, assuming a large storm 

results in extraordinary costs about once a decade. Because most residential yard 

trees are not littering the streets with leaves, it was assumed that cleanup costs for 

yard trees were 10 percent of those for public trees.

Inspection and administration costs—

Municipal tree programs have administrative costs for salaries of supervisors and 

clerical staff, operating costs, and overhead. Our survey found that the average 

annual cost for inspection and administration associated with street- and park-tree 

management was $3.50 per tree ($0.384 per in d.b.h.). Trees on private property do 

not accrue this expense.

Calculating Net Benefits

Benefits Accrue at Different Scales

When calculating net benefits, it is important to recognize that trees produce 

benefits that accrue both on- and offsite. Benefits are realized at four scales: parcel, 

neighborhood, community, and global. For example, property owners with onsite 

trees not only benefit from increased property values, but they may also directly 

benefit from improved human health (e.g., reduced exposure to cancer-causing 

ultraviolet radiation) and greater psychological well-being through visual and direct 

contact with plants. However, on the cost side, increased health care costs owing 

to allergies and respiratory ailments related to pollen may be incurred because of 

nearby trees. We assume that these intangible benefits and costs are reflected in 

what we term “aesthetics and other benefits.”

The property owner can obtain additional economic benefits from onsite trees 

depending on their location and condition. For example, carefully located onsite 

trees can provide air-conditioning savings by shading windows and walls and 
Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting

107

cooling building microclimates. This benefit can extend to adjacent neighbors who 

benefit from shade and air-temperature reductions that lower their cooling costs.

Neighborhood attractiveness and property values can be influenced by the 

extent of tree canopy cover on individual properties. At the community scale, benefits are realized through cleaner air and water, as well as social, educational, and 

employment and job training benefits that can reduce costs for health care, welfare, 

crime prevention, and other social service programs.

Reductions in atmospheric CO2 concentrations owing to trees are an example of 

benefits that are realized at the global scale.

Annual benefits are calculated as:

B = E + AQ + CO2 + H + A

where

E = value of net annual energy savings (cooling and heating)

AQ = value of annual air-quality improvement (pollutant uptake, avoided power 

plant emissions, and BVOC emissions)

CO2 = value of annual CO2 reductions (sequestration, avoided emissions, 

release from tree care and decomposition)

H = value of annual stormwater-runoff reductions

A = value of annual aesthetics and other benefits

On the other side of the benefit-cost equation are costs for tree planting and 

management. Expenditures are borne by property owners (irrigation, pruning, and 

removal) and the community (pollen and other health care costs). Annual costs (C) 

are the sum of costs for residential yard trees (CY ) and public trees (CP ): 

CY = P + T + R + D + I + S + Cl + L

CP = P + T + R + D + I + S + Cl + L + A

where

P = cost of tree and planting

T = average annual tree pruning cost

R = annualized tree and stump removal and disposal cost

D = average annual pest- and disease-control cost

I = annual irrigation cost

S = average annual cost to repair/mitigate infrastructure damage

Cl = annual litter and storm cleanup cost

L = average annual cost for litigation and settlements from tree-related claims

A = annual program administration, inspection, and other costs

Net benefits are calculated as the difference between total benefits and costs:

Net benefits = B – C

Benefit-cost ratios (BCR) are calculated as the ratio of benefits to costs:

BCR = B / C
108

GENERAL TECHNICAL REPORT PSW-GTR-206

Limitations of This Study

This analysis does not account for the wide variety of trees planted in Temperate 

Interior West communities or their diverse placement. It does not incorporate the 

full range of climatic differences within the region that influence potential energy, 

air quality, and hydrology benefits. Estimating aesthetics and other benefits is 

difficult because the research in this area is not well developed. We considered only 

residential and municipal tree cost scenarios, but realize that the costs associated 

with planting and managing trees can differ widely depending on program characteristics. For example, our analysis does not incorporate costs incurred by utility 

companies and passed on to customers for maintenance of trees under power lines. 

However, as described by examples in chapter 3, local cost data can be substituted 

for the data in this report to evaluate the benefits and costs of alternative programs.

In this analysis, results are presented in terms of future values of benefits and 

costs, not present values. Thus, findings do not incorporate the time value of money 

or inflation. We assume that the user intends to invest in community forests and 

our objective is to identify the relative magnitudes of future costs and benefits. 

If the user is interested in comparing an investment in urban forestry with other 

investment opportunities, it is important to discount all future benefits and costs to 

the beginning of the investment period. For example, trees with a future value of 

$100,000 in 10 years have a present value of $55,840, assuming a 6 percent annual 

interest rate.
This publication is available online at www.fs.fed.us/psw/. You may also order additional 

copies of it by sending your mailing information in label form through one of the following 

means. Please specify the publication title and series number.

Fort Collins Service Center 

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

Telephone (970) 498-1392

FAX (970) 498-1122

E-mail rschneider@fs.fed.us

Mailing address Publications Distribution

Rocky Mountain Research Station

240 West Prospect Road

Fort Collins, CO 80526-2098

Pacific Southwest Research Station

800 Buchanan Street

Albany, CA 94710

PSW-GTR-206 Temperate Interior West Community Tree Guide: Benefits, Costs, and Strategic Planting