1

The Natural Inquirer • Volume 6 Number 1

Volume 6, Number 1 • Urban Forest Edition 

What You See Is 

Not What You Get page 8

Good to the

Last Drip 

page 38

Don’t be So 

Fuel-ish! 

page 45

Yard Sale! 

page 52

I’ve Got You 

Covered page 17

Balancing 

Act page 31

Social Groupies page 24
Natural Inquirer

Barbara McDonald

USDA Forest Service

Research and Development

Athens, GA

Jessica Nickelsen

USDA Forest Service

Research and Development

Athens, GA

Teri Heyer

USDA Forest Service

State and Private Forestry

St. Paul, MN 

USDA Forest Service 

scientists highlighted 

in the journal:

Michael Bowker

Ken Cordell

Paul Gobster

Gordon Heisler

Scott Maco

Gregory McPherson

David Nowak

Jim Simpson

Jack Stevens

Other scientists 

highlighted in the journal:

Richard Grant

Christopher Luley

David Newman

Klaus Scott

Tymur Sydor

Susan Ustin

Qingfu Xiao

Produced by:

USDA Forest Service

Dale Bosworth, Chief

Research and Development

Washington, DC

Ann Bartuska, Deputy Chief

Resource Valuation and Use 

Research Staff

David Cleaves, Director

State and Private Forestry

Washington, DC

Joel Holtrop, Deputy Chief

Conservation Education Staff

Safiya Samman, Acting 

Director

Iris Velez, Acting Assistant 

Director

With thanks to:

Michelle Andrews

Resource Valuation and Use 

Research Staff

USDA Forest Service

Athens, GA

India Hall

Conservation Education 

Staff

USDA Forest Service

Washington, DC

Katrina Krause

Resource Valuation and Use 

Research Staff

USDA Forest Service

Athens, GA

Ed Dickerhoof

Resource Valuation and Use 

Research Staff

USDA Forest Service

Washington, DC

Todd Nickelsen

Technology Integration 

Specialist

Coile Middle School

Athens, GA

Shelley Masters

Teacher

Coile Middle School

Athens, GA

Renee McKinney

Teacher

Mason Middle School

Mason, OH

Dudley Hartel

Center Coordinator,

Southern Center

for Urban Forest 

Research and Information

USDA Forest Service

Athens, GA

Urban and Community 

Forestry

USDA Forest Service

Washington, DC

Office of Communication

USDA Forest Service

Washington, DC

USDA Forest Service

Southern Research Station

Athens, GA

Agriculture in the Classroom

Cooperative State Research, 

Education, and Extension 

Service, USDA

Washington, DC

Urban Forest Edition • Volume 6, Number 1 • Spring 2005

2

The Urban Forest Edition
3

The Natural Inquirer • Volume 6 Number 1

Editorial Review Board 

Comments about individual articles 

from this edition from the Natural 

Inquirer Editorial Review Board:

“ The article overall was good because they used the right words to 

help explain what they were talking 

about.”

“ I got confused about the behavior of 

social groups.”

“ It was a good article to read for 

middle schoolers. It was also appropriate enough for us and very 

entertaining.”

“ Use enthusiasm. I think it needs 

more excitement. Use more actions 

and exclamations.”

“ I thought the article was alright but 

some stuff you really don’t understand, but it is interesting.”

“Nice equations. Made me think.”

“ I think it was okay but it had some 

words I didn’t know.”

“ I thought it was very easy to understand. I like how they have the 

glossary on the first 

page. I learned a lot about street 

trees and sidewalk trees.”

“Good title. Very catchy!”

“ The article was okay. I learned a 

little from the experiment. I’m not 

into science so it was a little boring 

to me.”

“ The article is too complex. It was 

hard for me to understand but it did 

have some interesting information.”

“ I think this article is very good. I 

hadn’t ever read about street trees 

and how much street they cover.”

“ These R some awesome equations! 

Excellent!”

“ The pronunciation guide is unnecessary to include. Overall, I think 

the article was great.”

“ Most of the people who will be 

reading will probably already know 

how to pronunciate these words.”

Shelley Master’s 8th grade class, Coile Middle School, Athens-Clarke County, GA

Todd Nickelsen’s 8th grade class, Coile Middle School, Athens-Clarke County, GA
4

The Urban Forest Edition

Note to educators

As teachers of science, you want 

your students to acquire abilities 

that will enable them to conduct 

scientific inquiry, and you want them to gain 

an understanding of the scientific inquiry 

process. Scientific inquiry can best be taught 

by integrating minds-on and hands-on 

experiences. Over time, such experiences 

encourage students to independently 

formulate and seek answers to questions 

about the world we live in. As educators, 

you are constantly faced with engaging 

your students in scientific inquiry in new 

and different ways. In an age of abundant 

technology, standard teaching strategies 

can become monotonous to today’s 

learners. The Natural Inquirer provides a 

fresh approach to science and a view of 

the outside world that is larger than the 

classroom and can still be used while in the 

school setting.

The Natural Inquirer is a science education 

resource journal to be used with learners 

from Grade 5 and up. The Natural Inquirer

contains articles describing environmental 

and natural resource research conducted by 

the United States Department of Agriculture 

(USDA) Forest Service scientists and their 

cooperators. These are scientific journal 

articles that have been reformatted to meet 

the needs of middle school students. The 

articles are easy to understand, aesthetically 

pleasing to the eye, contain glossaries, and 

include hands-on activities. The goal of the 

Natural Inquirer is to stimulate critical reading 

and thinking about scientific inquiry and 

investigation while learning about ecology, 

the natural environment, and natural 

resources.

Science Education Standards and 

Evaluations: In the back of the journal, 

you will find a matrix that allows you to 

identify articles by the national science 

education standards that they address. You 

will also find evaluation forms in the back 

of the journal. Please make copies of these 

evaluation forms and have your students 

complete them after they complete each 

article. Also, please complete the evaluation 

form for teachers. Send the evaluation forms 

to the address listed below. The address is 

also listed at the bottom of the evaluation 

forms. You and your students may also 

complete the evaluation forms online by 

visiting http://www.naturalinquirer.usda.gov. 

This journal was created by 

Environmental and Science Education, an 

education program of the USDA Forest 

Service. If you have any questions or 

comments, please contact:

Dr. Barbara McDonald

USDA Forest Service

320 Green St.

Athens, GA 30602-2044

706.559.4224

barmac@bigfoot.com

Educator Resources:

Visit the updated Natural Inquirer Web site at 

http://www.naturalinquirer.usda.gov. From this 

site, you can read and download lesson plans, 

word games, and other resources to help you 

use the Natural Inquirer in your classroom. 

Visit the Natural Inquirer Web site: 

http://www.naturalinquirer.usda.gov
5

The Natural Inquirer • Volume 6 Number 1

Note to Educators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

About the Natural Inquirer . . . . . . . . . . . . . . . . . . . . . . . 6 

Who Are Scientists? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Welcome to the Natural Inquirer

Urban Forest Edition . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Features

What You See Is Not 

What You Get:

The Difference Between Visible Sunlight 

and Ultraviolet Radiation . . . . . . . . . . . . . . . . . . . . . . . 8

I’ve Got You Covered:

The Amount of Pavement Covered by 

Street Trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Social Groupies:

How Different Groups Use Urban Parks . . . . . . . . . . . 24

Balancing Act:

Urban Trees and the Carbon Cycle . . . . . . . . . . . . . . 31

Good to the Last Drip:

How Urban Trees Help To Reduce Pollution . . . . . . . 38

Don’t Be So Fuel-ish!

How Much Fuel Is Saved When Cars Are 

Parked in the Shade? . . . . . . . . . . . . . . . . . . . . . . . . 45

Yard Sale!

How Trees Affect the Selling Price of Houses . . . . . . 52

Reflection Section Answer Guide . . . . . . . . . . . . . . . . 62

Sample Natural Inquirer Lesson Plan . . . . . . . . . . . . . 69

Student Evaluation Form . . . . . . . . . . . . . . . . . . . . . . . 72

Teacher Evaluation Form . . . . . . . . . . . . . . . . . . . . . . . 73

Which National Science Education Standards 

Can Be Addressed by the Natural Inquirer? . . . . . 74

What Is the USDA Forest Service? . . . . . . . . . . . . . . . 75

What Is Agriculture in the Classroom? . . . . . . . . . . . . 75

What Is the Urban and Community Forestry 

Program? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Web Site Connections . . . . . . . . . . . . . . . . . . . . . . . . . 75

The Natural Inquirer is reproduced on recycled paper 

with soy-based inks. Please pass this journal along or 

recycle it when you have finished using it.

page 8

page 38

Contents

page 31
6 The Urban Forest Edition

Scientists report their research in 

journals, which are special booklets 

that enable scientists to share 

information with one another. This journal, 

the Natural Inquirer, was created so that 

scientists can share their research with you 

and with other middle school students. Each 

article tells you about scientific research 

conducted by scientists in the USDA Forest 

Service. If you want to know more about the 

USDA Forest Service, you can read about it 

on the back cover of this journal, or you can 

visit the Natural Inquirer Web site at http://

www.naturalinquirer.usda.gov. 

All of the research in the Natural Inquirer

is concerned with nature, such as trees, 

forests, animals, insects, outdoor activities, 

and water. First, you will “meet the scientist” 

who conducted the research. Then you will 

read something special about science and 

about the natural environment. You will also 

read about a specific research project. This is 

written in the format that scientists use when 

they publish their research in journals. Then, 

YOU will become the scientist when you 

conduct the FACTivity associated with each 

article. Don’t forget to look at the glossary and 

the special sections highlighted in each article. 

These sections give you extra information.

At the end of each section of the article, 

you will find a few questions to help you think 

about what you have read. These questions 

are not a test! They should help you to think 

more about the research. Your teacher may 

use these questions in a class discussion.

About the Natural Inquirer

Who are scientists?

Scientists are people who collect and 

evaluate information about a wide range 

of topics. Some scientists study the 

natural environment. To be a successful 

environmental scientist, you must:

b Be curious–You must be interested in 

learning.

b Be enthusiastic–You must be interested 

in an environmental topic.

b Be careful–You must be accurate in 

everything that you do.

b Be open minded–You must be willing to 

listen to new ideas.

b Question everything–You must think 

about what you read and observe.
7

The Natural Inquirer • Volume 6 Number 1

Welcome

to the Urban Forest Edition of the Natural Inquirer!

What are urban forests? Urban 

forests are the trees and other 

plants that grow where people 

live, go to school, work, and play. Even if 

you live in a rural community, the trees in 

your yard, around buildings, and in parks 

are called urban forests. Calling them 

urban forests helps you to see that they are 

different from the kind of forests that grow 

in large undeveloped areas. Urban forests 

include trees in community parks and other 

public land, along streets, in neighborhoods, 

around businesses and industry, and just 

about everywhere in a community. You will 

find urban forests almost anywhere that you 

find people living, going to school, working, 

and playing. 

Urban forests provide many benefits to 

people and to their communities. Trees and 

other plants help to slow soil erosion, reduce 

noise, provide homes for wildlife, and provide 

recreational opportunities. Can you imagine 

a park without trees? There are other 

benefits as well. Benefits of urban forests 

include—

b Reducing the amount of rainwater going 

down storm drains.

b Improving air quality.

b Increasing the value of property.

b Making communities more attractive.

b Keeping the temperature cooler in the warm 

summer months.

You will read about some of these benefits 

in this edition of the Natural Inquirer. Even 

though you may be surrounded by urban 

forests, you might never have thought about 

all of the benefits that they provide to you and 

your community. 

Did you know that—

b Urban forests can help protect you from 

ultraviolet radiation?

b Different groups of people like to picnic in 

different ways?

b Urban forests can reduce the amount of fuel 

used by vehicles?

b The average tree growing in a yard could be 

worth almost $1,000?

b Urban forests can help reduce the amount 

of pollution being washed into streams and 

rivers?

b Urban trees and the machines used to take 

care of them are a part of the carbon cycle?

b Most of the benefits from urban trees come 

from their branches and leaves?

 

You will learn all about urban forests in 

this edition of the Natural Inquirer. You will 

also learn about the scientists who study 

urban forests. When someone says the word 

“forest,” people usually think about the large 

forests located outside of cities and towns. 

Now, when you hear the word “forest,” you 

will also think about the urban forest that 

makes your community more attractive, 

healthier, cooler, and a lot more fun!
8 The Urban Forest Edition

What You 

See Is Not 

What You Get:

The Difference Between 

Visible Sunlight and 

Ultraviolet Radiation
9

The Natural Inquirer • Volume 6 Number 1

Meet the Scientists

Dr. Grant: 7My favorite 

experience as a scientist 

is solving a puzzle of why 

something in nature acts 

like it does or discovering 

an explanation for 

something I have seen 

many times but did not 

know why it happened.

Dr. Heisler: 5My favorite 

experience as a scientist 

is getting to understand 

something about how 

nature works. I also like to 

successfully develop or 

use a method to measure 

how nature works.

 Thinking About 

Science 

Scientists use many ways to discover 

new knowledge. Sometimes collecting 

existing information from many sources 

and putting it together in one report 

is a valuable addition to science. This 

is similar to what you do when you 

write a paper using information from 

the library and the Internet. In this 

study, the scientists collected information from 

past research and added it to their own research 

findings. In this research, the scientists wanted to 

know how much is already known about ultraviolet 

radiation in urban areas.

Glossary:

ultraviolet radiation (all tra 

vi o let ra de a shun): Invisible 

rays of light lying beyond the 

violet end of the spectrum.

immune system (im myoon

sis tem): The system within the 

body that protects the body 

from disease; includes white 

blood cells and antibodies.

relationship (re la shun ship): 

Two or more things that are 

connected in some fashion.

optical (op tuh kül): Relating to 

vision or to light.

species (spe sez): Groups 

of organisms that resemble 

one another in appearance, 

behavior, chemical processes, 

and genetic structure.

quantity (kwän tä ti): An 

amount or portion.

tree crown (tre krown): The 

upper green section of a tree 

with leaves or needles.

reflectivity (re flek tiv uh te): 

The property of casting back 

light, heat, sound, etc.

average (av rij): The usual kind 

or amount. The number gotten 

by dividing the sum of two or 

more quantities by the number 

of quantities added.

canopy (kan uh pe): Anything 

that covers like a roof. On a tree, 

the area of leaves that cover the 

ground.

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing
10 The Urban Forest Edition

Introduction

Scientists have known that there is a 

difference between the sun’s visible radiation 

and invisible ultraviolet radiation from the 

sun. (See figure 1.) Ultraviolet radiation 

is separated into 3 types: UVA, UVB, and 

Figure 1. Electromagnetic Spectrum

Figure 2. UVA, UVB, and UVC radiation and 

their relationship to ozone in the atmosphere.

Thinking 

About the 

Environment 

All life on Earth needs the sun 

because it is the original source 

of all of our energy and food. 

Sometimes, however, we can get too much 

of a good thing. Take ultraviolet radiation, for 

example. Ultraviolet radiation, or UV radiation, 

comes from the sun and is invisible. UV 

radiation is a part of the electromagnetic

(e lek tro mag net ik) spectrum (figure 1). 

What makes UV radiation good? UV radiation 

causes the skin to create Vitamin D, which 

helps people to absorb calcium. A little bit 

of sunlight can also protect people from 

some kinds of nonskin cancers. Too much 

UV radiation, however, can be hazardous to 

human health. If you are going to be in the 

sun for a long time, use sunscreen or cover 

your skin. Some of the negative impacts of 

too much UV radiation include sunburn, eye 

damage, and skin cancer. Because too much 

UV radiation may damage a person’s immune 

system, other cancers and diseases may be 

related to having too much sun exposure. 

UVC. UVB radiation is best known for its 

ability to cause damage to human health. At 

the short end of the UVB wavelength, where 

UVB meets UVC, almost all of the radiation 

is absorbed by ozone in the atmosphere. At 

the longer end of the wavelength, UVB meets 

UVA radiation. Ozone does not absorb very 

much of the radiation at this end of the UVB 

spectrum (figure 2). 

When it is hot or very sunny, people often 

seek the shelter of a tree’s shade to protect 

them from the sun. This is because the tree’s 

leaves provide shade from the sun’s visible 

radiation. Although leaves protect people from 

the sun’s visible radiation, they may not protect 

people from invisible UVB radiation. The 

scientists in this study were interested in trees 

growing in urban areas. They wanted to know 

whether the shade that we can see under urban 

trees protects people from UVB radiation. 

Ultimately, it is shade from the UVB radiation 

that is the most important for human health.

Reflection Section

b What question did the scientists want to answer?

b Why is this question important?

xrays UV visible

atmospheric ozone

UVC UVB UVA

Gamma

rays x-rays ultra-violet Infra-red Microwaves Radio waves visible light

Short wavelength long wavelength
11

The Natural Inquirer • Volume 6 Number 1

Method

The scientists read over 100 research 

papers that were related in some way to 

the question about the sun’s radiation on 

urban trees. Urban trees are the trees that 

grow where people live, work, and play. The 

scientists also had the results from their own 

previous research. The scientists were most 

interested in the optical properties of leaves. 

They read research papers that reported how 

much of the sun’s visible radiation and UVB 

radiation passes through leaves. They read 

research about how the leaves from different 

tree species reflect visible radiation and UVB 

radiation. They read research about how the 

quantity of visible radiation compares with 

the quantity of UVB radiation in the sunny 

areas near urban trees. They included the 

information they had collected themselves 

about the amount of radiation reaching the 

area under urban trees. Then, they put all of 

the information together into one report.

Reflection Section

b Name two reasons why is it important to find out 

what is already known about something before 

doing an experiment or collecting your own 

information about it.

b From your own observation, would you say that 

leaves allow the sun’s visible radiation to pass 

through them? Why or why not?

Findings

The scientists found that while leaves allow 

some of the sun’s visible radiation to pass 

through them, tree crowns do not allow much 

light to pass to the ground. This is because 

most of the sun’s rays encounter many leaves 

as they attempt to get through the crown. 

Therefore, the scientists focused their 

attention on the reflectivity of leaves (figure 

3). They found that the reflectivity of visible 

radiation is much higher than invisible UVB 

Figure 3. The reflection of the sun’s radiation 

off of a leaf.

radiation. For example, about 10 to 30 percent 

of the sun’s visible radiation is reflected off of 

leaves. About 3 to 6 percent of the sun’s UVB 

radiation is reflected off of leaves.

In dense forests you can usually only see 

a small part of the sky from the forest floor. 

In these forests, only a little visible radiation 

and UVB radiation reach the forest floor. This 

is because there are many layers of leaves 

shielding the forest floor from the sky. 

The situation is very different in urban 

forests. In urban forests, trees either are 

planted alone or with just a few others (figure 4). 

In urban forests, people can usually see the 

Figure 4. In an urban forest, people can see 

the sky beyond the edge of the tree crown.

Visible and UV radiation
12

The Urban Forest Edition

Area Under Tree Canopy Percent Reduction 

in UVB Radiation

Percent Reduction 

in Visible Radiation

1. Sunlit Area–With Leaves 39 3

2. Shady Area–With Leaves 63 84

3. Sunlit Area–No Leaves 40 6

4. Shady Area–No Leaves 56 73

5. Sunlit Area and Building–No Leaves 59 5

6. Shady Area and Building–No Leaves 70 47

Table 1. Average percent reductions in the sun’s visible radiation and invisible UVB radiation 

below a street tree canopy.

sky beyond the edge of the tree crown. The 

scientists used special equipment to measure 

the amount of radiation reaching the ground, 

both in the open and under urban trees 

(figures 5 and 6). UVB radiation is widely 

scattered across the sky. If a person can see 

much of the sky, the UVB radiation reaches 

them even when they are under a tree.

The scientists reported some of their own 

research, in which they measured the amount 

of radiation reaching six types of areas (table 1). 

The six areas were:

1. Sunlit areas under a tree in summer 

(with leaves)

2. Shady areas under a tree in summer 

(with leaves)

3. Sunlit areas under a tree in winter 

(no leaves)

4. Shady areas under a tree in winter 

(no leaves)

5. Sunlit areas under a tree in winter with 

a building nearby (no leaves)

6. Shady areas under a tree in winter with 

a building nearby (no leaves)

Figure 5. Scientists use special sensor 

equipment placed under a tree or on the 

ground to measure the amount of the sun’s 

radiation reaching the ground. Notice the clear 

bubble on the top of the equipment.

Figure 6. If the equipment could see, this is an 

example of what it would see.
13

The Natural Inquirer • Volume 6 Number 1

Figure 7. Sunny areas near urban trees 

experienced a greater reduction in UVB 

radiation than visible radiation.

No matter what you look 

at in nature, it is a part of a 

system. Systems can exist 

at a number of different 

levels, from small and simple 

to large and complex. Your 

body is a good example. You 

have different organs that 

are systems composed of 

cells. Your whole body is a 

larger, more complex system 

that is composed of different 

organs. As systems get larger 

and more complex, new 

properties appear that were 

not evident at the smaller 

and simpler levels. In this 

study on UVB radiation, the 

crowns of trees demonstrate 

this idea. Tree crowns are 

made up of many individual 

leaves growing on branches. 

An individual leaf is one type 

of system. When hundreds 

or thousands of leaves make 

up a tree crown, new things 

are possible. Now, visible 

radiation and UVB radiation 

from the sun can be partially 

blocked. The temperature 

under the tree is now lower 

in the warm summer months. 

Birds now have a place to 

build nests. As systems get 

larger and more complex, 

new things are possible that 

were not possible before. ■

Thinking About Ecology

Look closely at table 1. If our eyes were 

able to see UVB radiation, the shadows cast 

by UVB radiation would be different than the 

shadows cast by visible radiation. Compare 

the numbers in areas 1 and 2 in each column. 

Then look at the numbers in areas 3 and 4 

in each column. Now look at the numbers in 

areas 5 and 6 in each column. You can see 

that the reduction in UVB radiation was more 

similar in sunny and shady areas than the 

reduction in visible radiation in sunny and shady 

areas. In sunny areas, not much visible radiation 

is reduced. In shady areas, a lot of the visible 

radiation is reduced. The radiation that we can 

see is not like the UVB radiation that we cannot 

see. The UVB radiation is scattered across the 

sky. When you can see a part of the sky from 

where you are standing, you are receiving some 

UVB radiation.

The scientists also found that in sunny areas 

close to urban trees, a greater percentage of 

UVB radiation was reduced even though the 
14

The Urban Forest Edition

Implications

If you are in a densely forested area and 

cannot see part of the sky above you, you are 

probably protected from UVB radiation. If you 

are standing under an urban tree or a small 

group of trees and you can see part of the sky 

beyond the edge of the tree crown, you still 

receive some UVB radiation. The amount of 

UVB radiation you receive depends on how 

much of the sky you can see. Larger, older 

visible radiation was not reduced (figure 7). 

This is because when people stand close to 

a tree, part of the sky is blocked by the tree. 

When a part of the sky is blocked, some of the 

UVB radiation is blocked as well.

Reflection Section

b In urban areas, some UVB radiation can be 

reflected off of buildings, sidewalks, streets, 

and fountains. Should you consider this source 

of UVB radiation when trying to protect yourself 

from the sun? Why or why not?

b Reread the last sentence in the last paragraph 

above. Why do you think that you receive less 

UVB radiation when standing in the sun next 

to a tree than when standing in the sun away 

from a tree?

Reflection Section

b Look at table 1 and read the paragraph below it. 

Put the scientists’ findings in your own words.

b What do you think these findings mean for 

protecting yourself from harmful UVB radiation?

trees provide more protection from UVB than 

smaller, younger trees. If you are in the sun but 

just outside of the shade of a large tree, you 

receive a smaller amount of UVB than if you 

were standing in the sun farther away from 

the tree’s shade. ■

From Heisler, G. M. & Grant, R. H. (2000). Ultraviolet radiation, 

human health, and the urban forest. USDA Forest Service 

General Technical Report NE-268, Newtown Square, PA.
15

The Natural Inquirer • Volume 6 Number 1

FACTivity

Placement of 

UV Detection Beads

Time of Year 

(Winter, Summer, Spring, 

Fall)

Observations

Sunlit Area Under a Tree (With Leaves)

Shady Areas Under a Tree (With Leaves)

Sunny Area Right Next to a Tree, but not 

Directly Under the Tree

Sunlit Areas Under a Tree With a Building 

Nearby

Shady Areas Under a Tree With a Building 

Nearby

Any Area of Your Choice

In this FACTivity, you will conduct an 

experiment to test the different amounts 

of UV radiation. Compare your results 

with the results of the scientists in 

this study. For this FACTivity, you will 

need UV detection beads. Divide UV 

detection beads into six different plastic 

petri dishes.

Place one petri dish in each of the 

areas listed below.

1. Sunlit area under a tree (with leaves).

2. Shady area under a tree (with 

leaves).

3. Sunny area right next to a tree, but 

not directly under the tree.

4. Sunlit area under a tree with a 

building nearby.

5. Shady area under a tree with a 

building nearby. 

6. Any other area you would like to 

compare.

Observe what happens to the UV 

detection beads placed in these areas 

and then record your results in the 

following table.

Were your results similar to the 

scientists’ results in this study? If not, 

why do you think there is a difference?

Teachers—

UV detection beads are inexpensive 

and can be ordered from vendors on the 

Web. Search on “UV detection beads.”
16 The Urban Forest Edition

Alternate FACTivity

In this FACTivity, students will use 

information from the U.S. Environmental 

Protection Agency (EPA) Sunwise 

program. Visit EPA’s Web site to can find 

out the daily UV radiation for your city: 

http://www.epa.gov/sunwise/uvindex.

html 

Record the daily UV Index for your 

hometown and for one city in each region 

of the United States. Record the results in 

the table below.

Compare the UV index results for each 

city. Calculate each city’s 2-week average 

UV index recording. Discuss results and 

why there are differences among cities. 

Web Site resources

Sun protection tips: 

http://www.epa.gov/sunwise/kids.html

Activities

http://www.cdc.gov/excite/skincancer/

index.htm

Name of 

Hometown

Southern 

City

Northeastern 

City

Midwestern 

City

Rocky 

Mountain 

City

Southwestern 

City Northwestern City

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14
17

The Natural Inquirer • Volume 6 Number 1

 I’ve Got You 

 Covered:

 The Amount of

 Pavement Covered

 by Street Trees
18 The Urban Forest Edition

Meet the Scientists

Mr. Maco: 0As a research forester, my curiosity about the 

natural world is encouraged. I am offered opportunities to 

explore questions for which answers are not known. My 

favorite experience with science is when answering one 

of these questions leads to an improvement in how we 

manage our forests, so that future generations can enjoy 

what we enjoy today.

Dr. McPherson: 8My favorite science experience is 

seeing a paper finally in print or giving a presentation to 

a large group and sensing their interest and excitement. 

The process of planning and conducting research is long 

and painstaking. One has to be patient because results 

don’t come quickly. However, the joy of seeing a project 

completed and knowing that it is valued by others is very 

gratifying.

Glossary:

global warming (glo bul wôrm ing): An increase 

in the average temperature of the Earth’s 

atmosphere.

intercept (in tür sept): To stop or interrupt the 

progress or intended course of something.

canopy (kan uh pe): Anything that covers like a 

roof. On a tree, the area of leaves that cover the 

ground.

inventory (in ven tôr e): A complete list of 

goods, supplies, possessions, etc.

radius (ra de us): A straight line that extends 

from the center to the outside of a circle or 

sphere.

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing

Thinking About 

Science

Scientists work to solve 

problems. These problems are 

identified because their solution 

provides a benefit to people. Sometimes a 

scientist’s research might be a part of a larger 

problem. By solving a small piece of the problem, 

scientists can provide information so that the 

larger problem might one day be solved. 

In this study, the scientists wanted to know 

how much of a city’s paved surfaces should 

be covered by trees. Paved surfaces include 

streets, sidewalks, and parking lots. Many 

benefits are provided by urban trees when 

they cover paved surfaces. To answer their 

question, they first needed a way to estimate 

the current amount of ground and pavement 

that urban trees cover. This is because the 

amount of benefits provided by urban trees is 

related to the amount of ground and pavement 
19

The Natural Inquirer • Volume 6 Number 1

Introduction

The trees that grow along urban streets 

are called street trees. Some street trees are 

planted between the street and the sidewalk 

(figure 2a). Other street trees are planted 

in a strip of land called the median, which lies 

in between the lanes of traffic (figure 2b). 

Trees that grow in front yards are considered 

street trees if part of their canopy covers 

public areas, such as the sidewalk or the street 

(figure 2c). Often, sidewalks have cut out 

areas where trees are planted (figure 2d).

that their canopies cover. Unless the scientists 

found out how much of the city’s paved 

surfaces were currently covered by trees, they 

could not determine whether more tree cover 

was needed.

Thinking About 

the Environment

Urban trees provide many benefits 

to people and their communities. 

Urban trees keep areas cooler in 

the summer, helping to lower energy 

use in buildings. Trees keep the air cleaner by 

reducing the amount of harmful pollutants in 

the air. They also help to prevent global warming

by reducing the amount of carbon dioxide going 

into the atmosphere. Trees hold the soil in place 

and intercept rainwater. When trees intercept

rainwater, they reduce the amount of water that 

runs into stormdrains and washes pollutants 

into streams and rivers. Urban trees also provide 

homes for birds and other urban wildlife and 

make urban areas more beautiful.

Most of these benefits depend on how much 

of the ground, including paved areas, the tree’s 

canopy covers (figure 1). Usually, the larger the 

area of ground or pavement that is covered by 

urban tree canopies, the greater the benefits to 

people.

Figure 1. A tree canopy.

Figure 2a. Street tree planted between the 

street and sidewalk.

Figure 2b. Street tree planted in the median 

strip.
20 The Urban Forest Edition

The scientists in this study wanted to know 

how much of the sidewalks and streets were 

covered by tree canopies in a particular urban 

area. Can you guess why they wanted to 

know this? If people do not know how much of 

something they have, then they do not know if 

they need more or less of it. 

Think about your own money. Let’s say that 

you want to buy a new DVD that costs $15. 

How do you find out if you need more or less 

money to buy the DVD? To determine this, 

you must count your money. 

When you count your money, you are 

taking an inventory of how much money you 

have. The scientists in this study wanted to 

take an inventory of how much ground and 

pavement was covered by street trees. By 

estimating this, they eventually will be able to 

recommend how cities can change the number 

of trees growing in cities and where the trees 

are planted. By doing this, cities can increase 

the amount of benefits people are receiving 

from street trees.

Figure 2c. Street tree planted in a front yard.

All living things grow and 

develop. This happens for 

individual living things, such 

as you and your classmates. 

Development means that 

as living things get older, 

they are able to do different 

and more complex things. 

When you think about it, 

you can see that infants do 

not just grow. They also 

develop. You can see this 

by watching infants learn 

to walk, talk, and then ask 

more complex questions. 

The idea of development can 

be demonstrated by urban 

forests. As urban forests get 

older, they are able to “do” 

things that they could not 

do when they were younger 

and smaller. For example, as 

tree crowns get larger, they 

are able to shade more of 

the pavement. They are able 

to slow more of the rainfall 

and prevent more pollution 

of streams and rivers. They 

keep larger areas cooler and 

provide places for different 

kinds of urban wildlife to live. 

They are able to produce 

flowers, nuts, and seeds and, 

therefore, reproduce. As 

you read this article, think 

about how the development 

of urban forests affects their 

ability to provide benefits to 

people. ■

Thinking About Ecology
21

The Natural Inquirer • Volume 6 Number 1

streets and sidewalks. For example, they added 

up all of the street lengths. They found that there 

were 240 kilometers of streets in the community. 

(How many miles is this? To calculate, multiply 

the number of kilometers by .621.) Then, they 

multiplied 240 by 10.7 meters (or 35 feet) to 

calculate the total area of street pavement. They 

estimated that the city had 256 hectares of street 

pavement. (How many acres is this? Multiply 

256 by 2.47 to find out.) They also estimated 

that there were 58 hectares of sidewalks in the 

community. (How many acres of sidewalks?)

Figure 2d. Street tree planted within a 

sidewalk cut out.

Findings

Overall, about 14 percent of the community’s streets and sidewalks were covered by 

street trees. Of this, about 23 percent of the 

tree canopy was over streets. (What percentage of the tree canopy was over sidewalks and 

other surfaces? Hint: Subtract 23 from 100 

to find out.) When the scientists compared 

sidewalks with streets, they found that about 

24 percent of the community’s sidewalks were 

covered by street tree canopies.

Method

The scientists estimated three types of tree 

canopy cover. First, they measured the radius of 

the area beneath each street tree canopy in the 

community. They assumed that this area would 

be roughly shaped in a circle. Then, they estimated 

the amount of canopy cover over streets alone. 

Finally, they estimated the amount of cover 

over streets and sidewalks together. They used 

mathematical equations to estimate the amount of 

cover over streets and sidewalks.

The scientists used existing information to 

estimate the total amount of pavement making up 

Reflection Section

b What were the scientists trying to do in this 

study?

b Can you think of two other items that you took an 

inventory of this past week? What were they?

Reflection Section

b What do you think the numbers 10.7 meters and 

35 feet represent?

b Do you think that the amount of tree canopy area 

covering streets and sidewalks was equal to the 

total amount of area that street tree canopies 

covered? Why or why not?

Reflection Section

b Why do you think a greater percentage of 

sidewalk area than street area was covered by 

tree canopies?

b Did this tell the scientists how many benefits 

people were receiving from street trees? Why or 

why not?
22

The Urban Forest Edition

Number of 

Acres in 

Streets

Number of 

Hectares in 

Streets

Number of 

Acres in 

Sidewalks

Number of 

Hectares in 

Sidewalks

Total Number 

of Acres in 

Streets and 

Sidewalks

Total Number 

of Hectares 

in Streets and 

Sidewalks

Number from 

“Methods” b b

Add Street 

Numbers and 

Sidewalk Numbers b b b b

Apply Percent 

from “Findings” b b b b

Apply Percent 

from “Findings” b b b b

Subtract 

Sidewalk Numbers 

from Total 

Numbers b b b b

FACTivity

The question you will answer 

in this FACTivity is: Were there more acres of 

streets or sidewalks covered by street tree 

canopies in this study? Before you answer 

this question, review the first Reflection 

Question under “Findings.” To answer this 

question, go to the “Method” and “Findings” 

sections. Using the information from those 

sections, complete the table below.

Now that you have these numbers, 

answer the question posed at the 

beginning of the FACTivity. Why is the 

percentage of sidewalk coverage higher 

than street coverage? Why are there more 

acres of street coverage than sidewalk 

coverage?

Implications

Using studies like this one, people can find 

out how much of their streets and sidewalks 

are covered by street tree canopies. This will 

help them to determine whether they might 

want to plant more street trees to shade more 

of the pavement. For example, what if the 

community in this study would like to have 25 

percent of their streets and sidewalks covered 

by trees? They now know that only 14 percent 

of their streets and sidewalks are covered by 

street trees. What might they do to reach 

their goal of 25 percent? ■

From Maco, S. E. and McPherson, E. G. (2002). Assessing 

canopy cover over streets and sidewalks in street tree 

populations. Journal of Arboriculture, (286): 270-276.

Reflection Section

b What is one reason it is important to know how 

much paved area street trees cover?

b Do you think it might be important to also 

estimate the amount of grassed areas that street 

trees cover? Why or why not?
23

The Natural Inquirer • Volume 6 Number 1

Alternate FACTivity

In this FACTivity, you will adopt-a-tree 

in your schoolyard. (Depending on how 

many trees there are around the school, 

you may need to adopt trees in pairs or 

groups rather than individually.) Create 

a tree journal from a notebook. Set 

time aside to make observations of the 

adopted tree. While observing the tree, 

perform some of the following activities: 

1. Create bark rubbings.

2. Collect dried leaves from the tree.

3. Conduct leaf identification.

4. Draw the tree during different 

seasons, focusing specifically on tree 

canopy.

5. Measure the diameter (diameter 

at breast height, or dbh) of the 

tree. (Visit http://www.cnr.vt.edu/

dendro/forsite/si4.htm for 

instructions on measuring dbh.)

6. Record insects and animals that live 

on or around tree. (Place a bed sheet 

on the ground underneath the tree. 

Shake the tree vigorously and then 

record insects that have fallen on to 

the bed sheet.)

7. Create a photo-biography of the tree.

8. Write a poem about the tree.

9. Develop a song about the tree and 

perform it for the class or other 

students in the school.

10. Celebrate Arbor Day by giving 

students in school a tour of all of the 

trees on the school grounds and 

provide information that you have 

collected about each tree.

11. Research the type of tree and create 

a Web page or PowerPoint® on the 

vital statistics of the tree.

12. Create a schoolyard map with tree 

location and types.

13. Calculate the amount of land 

covered by trees in your schoolyard. 

This could be tracked over time.

14. Identify a list of benefits provided by 

the trees at your school.

Teachers— 

See the Schoolyard Tree Inventory and 

Biodiversity Project Lesson Plan on page 

69 for more schoolyard tree activities.
24

The Urban Forest Edition

Social 

Groupies:

How Different Groups 

Use Urban Parks
25

The Natural Inquirer • Volume 6 Number 1

Meet the Scientist

Thinking About 

Science

Scientists study a lot of 

different things. Usually, people 

think about the kind of science 

that is concerned with things like 

Earth, or diseases, or space. There is another 

category of science known as the social 

sciences. The social sciences are concerned 

with the things that people think, feel, believe, 

say, or do. The social sciences may also be 

concerned about the behavior of groups 

of people. Groups could include American 

families living in South Africa, 12-year old boys 

in Oklahoma who play soccer, middle school 

science students in Tillman Middle School, or 

just about any group of people. 

Pretend that you are a social scientist. 

Name three different groups of people that 

you might like to study. Any group that you 

identify should have a common characteristic. 

You should also limit the group by identifying a 

geographic limit. Use your imagination!

Glossary:

urban (ür bun): Living in or having to do with cities or 

towns.

manager (ma ni jür): A skilled person who directs or 

manages something.

geographic (je o graf ik): Having to do with Earth’s 

division into areas such as continents, seas, countries, 

States, etc.

resources (re sôr sez): A supply of something to take 

care of a need.

public land (pub lik land): Land that is owned by the 

people as a whole; land that is taken care of for the good 

of all of the people. 

ethnic (eth nik): Of or describing a group of people who 

have the same language, culture, etc.

survey (sür va): A method used to ask questions to 

collect information.

interviewer (in tür vyu ür): A person who asks another 

person about his or her opinions, activities, etc.

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing

Dr. Gobster: 6 My favorite experience 

as a scientist is talking with people. As a 

social scientist who studies how people 

think about and use urban parks, I get to 

visit some very nice places and talk with 

people about what they like to do best 

when they spend their free-time out of 

doors. I hope that the information I get 

from them helps managers to make parks 

even better for people.

Photo by Savanna Dickhut
26 The Urban Forest Edition

The scientist trained interviewers from 

different ethnic backgrounds. African 

American interviewers asked questions 

of African American park visitors. Latino 

interviewers asked questions of Latino park 

visitors. Asian interviewers asked questions of 

Asian park visitors. All interviewers asked the 

same questions and recorded the answers. In 

total, the interviewers talked with 500 African 

Figure 1. Location of Chicago, Illinois

Method

The scientists conducted a survey of park 

users in Chicago, Illinois (figure 1). Most of 

the people they talked with were White. The 

scientists wanted to learn about all of the 

people who visit the park, including people 

of different ethnic backgrounds. Therefore, 

they conducted another survey that focused 

on Latino, African American, and Asian 

visitors. The scientist trained people, called 

interviewers, to ask these people questions 

about their park use. 

Thinking About the 

Environment

Have you ever planned how you 

are going to spend your weekend? 

Do you plan how you will spend 

your allowance? Planning is an 

important tool that helps people 

and communities to use their 

resources more wisely. Resources include things 

like money, time, or even school supplies. If 

you plan ahead about how you will use your 

resources, you will have a better chance of 

identifying future opportunities or problems. 

People are not the only ones who plan 

ahead. Groups of people living in communities 

can also plan how they will use their shared 

resources. One of the resources they plan for 

is how they will use public land, including urban 

park land.

Introduction

People visit parks to do many different 

activities, such as play basketball, baseball, 

sunbathe, swim, walk, picnic, or go bicycling. 

If park managers know what people like to do 

in a particular park, they can do a better job of 

providing the opportunity. In the past, social 

scientists studied what some people like to do 

in parks. The scientists learned more about 

what White visitors liked to do in parks than 

people of other ethnic backgrounds. Because it 

is important to learn about all park visitors, the 

scientist decided to conduct another survey.

The question the scientist wanted to 

answer in this study was: What activities do 

people of different ethnic backgrounds do 

while visiting an urban park? This information 

could then be used to help park managers 

develop a plan for the park’s future. That plan 

would provide better opportunities for people 

of different ethnic backgrounds.

Reflection Section

b What is the question that the scientist 

wanted to answer?

b If you were the scientist, how would you learn 

what kind of activities people of different ethnic 

backgrounds do when they visit a park?

North
27

The Natural Inquirer • Volume 6 Number 1

Figure 2. The percentage of visitors participating in the five most popular activities

American, Latino, and Asian park visitors. 

The scientist compared all of the answers with 

each other, including the answers given by 

White park visitors in the earlier survey.

Findings

All visitors, regardless of their ethnic 

background, liked to do some of the same 

activities. The activities everyone liked to do 

included (figure 2):

• walking

• swimming

• beach sunning

• picnicking and barbecuing

• visiting the zoo

• sitting and relaxing 

• bicycling

There were also some differences between 

the ethnic groups. Latinos picnicked and 

watched sports more than other groups. 

African Americans got together more often 

Reflection Section

b Why do you think that it was important to 

ask all of the visitors the same questions?

b Based on your own experience, do you think that 

people from different ethnic backgrounds like 

to do the same things or different things when 

visiting an urban park?

25.6

22.3

21

16.5

14

Swimming/

Beach 

sunning

Picnicking

and 

barbecuing Walking

Sitting

and

relaxing

Bicycling

5%

10%

15%

20%

25%

30%

Percent of Visitors
28 The Urban Forest Edition

with family and friends. Like Latinos, Asians 

picnicked more; and they also participated 

in festivals more than other groups. Whites 

bicycled, walked, jogged, and walked their 

dogs more often.

The scientist also discovered another 

difference between Whites and other ethnic 

groups. Whites usually came to the park alone 

or with one other person. African Americans, 

Latinos, and Asians came more often with 

a larger group that usually included family 

members (figure 3). More than 10 percent of 

the Latinos and Asians who visited the park 

came with groups of more than 10 people. 

Implications

There were some similarities in all of 

the visitors’ activities in the urban park, 

regardless of their ethnic background. There 

were also differences. This study tells park 

managers what different groups might like to 

do. Information like this helps managers to 

consider the choices of people who come from 

different ethnic backgrounds. When managers 

are making plans for improvements to their 

park, they can use information like this to do a 

better job for all park visitors. ■

Figure 3. Percentage of park use by families 

for African Americans, Latinos, and Asians.

Reflection Section

b Are you surprised by the similarities and 

differences between the groups? Why or why not? 

Discuss with your class about whether you have 

observed the same things in your local parks. 

If your observations are different, how are they 

different? Why do you think that they are different?

b When you visit a local park with others, how would 

you describe your group? Do you go with your 

family? With friends? What kind of things do you 

do when you visit a park?

Reflection Section

b Why is it important to think about all of the users 

of urban parks?

From: Gobster, P. H. (2002 ). Managing parks for a racially 

diverse clientele. Leisure sciences, 24: 143-159.

39%

40%

50%

Blacks Latinos Asians
29

The Natural Inquirer • Volume 6 Number 1

FACTivity

In this FACTivity, you will 

use the findings from this research to 

design a picnic area. The picnic area must 

be suitable for park users from different 

ethnic backgrounds. After your teacher 

divides the class into groups of four, each 

group will design a picnic area.

First, list the ways different ethnic 

groups use the park. (Hint: Re-read the 

Findings section.) Beside this list, describe 

the kind of picnic area and equipment that 

could be used to make this picnic area an 

enjoyable place for all different types of 

ethnic groups. You can use the example 

on the next page to get you started.

You should now have a list of items that 

you might want to include in your picnic 

area. Unfortunately, you do not have 

enough resources to provide for all of the 

items. (What are resources? In this case, 

your resources are land and money.) You 

must set priorities for the types of items 

that you will provide in your picnic area. 

Each team will design a picnic area for .5 

acres. You will have $10,000 to complete 

your picnic area.

In the table on the next page, list the 

items you would like to buy, how many of 

each item you would like to buy, and how 

much they will cost.

As a team, decide on how you will set 

priorities for the activities you will provide 

in your picnic area. Your team should 

consider providing activities for all ethnic 

groups. Also, think about things like—is 

your picnic area accessible to people with 

disabilities? The team should strive make 

the picnic area the most accessible and 

user-friendly area for all ethnic groups.

The picnic areas should be designed on 

a large sheet of paper with all items and 

areas identified. Design the picnic area 

from a bird’s-eye view or draw an “artist’s 

concept” of the picnic area. 

After completing your design and 

budget, your teacher will have you present 

them to class. The class can vote on the 

best design.

You’ve probably heard 

the saying, “Diversity is the 

spice of life.” It is not only 

the spice of life, diversity is a 

property of all living things. 

When you think about Earth, 

you will realize that Earth 

has a great diversity of living 

things. There are insects, 

microorganisms, plants of 

all sizes, small and large 

animals living in the wild, 

and humans. Within each of 

these groups of living things, 

there is also a great amount 

of diversity. This idea is 

demonstrated in this research 

by the diversity of people and 

the diversity of their choices 

when visiting a park. When 

you think about it, you may 

realize that while there are 

similarities among living 

things, diversity helps to keep 

our Earth and its living things 

healthy. ■

Thinking About Ecology
30 The Urban Forest Edition

Ethnic Group Number of Individuals in 

Groups That Use Park Description of Picnic Area Needed

Latino Larger groups, sometimes 

10 or more people

Large picnic pavilions, extra picnic tables, large 

trash cans

Item How Many You Would Like To Buy How Much the Item Costs

Picnic Tables 5 $300 each
31

The Natural Inquirer • Volume 6 Number 1

Balancing Act:

Urban Trees and 

the Carbon Cycle
32 The Urban Forest Edition

Meet the Scientists

Dr. Nowak:5My favorite 

experience in science 

is seeing people use 

the new information we 

generate to improve the 

urban environment.

Dr. Luley:5My favorite 

science experience 

is watching a tree go 

through each season 

and understanding 

what is happening to 

the tree. Each season 

has its own unique set 

of changes that we all 

can see. There is also 

a whole set of changes 

that occur in the tree at 

the cell and subcellular 

level that correspond to 

these visual changes. 

Making the connection 

between the two and 

understanding how we 

better manage our trees 

with this knowledge has 

been a very rewarding 

experience. 

Mr. Stevens:5My 

favorite experience in 

science is being a part 

of the process of solving 

environmental problems 

that affect the health 

and well-being of urban 

residents.

Glossary:

emitted (e mi ted): Discharged 

or sent out.

fossil fuel (fos ul fyool): Fuel, 

such as coal, petroleum, or 

natural gas, formed from the 

fossilized remains of plants and 

animals.

photosynthesis (fo to sin thuh 

sis): The process by which 

green plants use sunlight to 

form sugars and starches from 

water and carbon dioxide.

species (spe sez): Groups 

of organisms that resemble 

one another in appearance, 

behavior, chemical processes, 

and genetic structure

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing
33

The Natural Inquirer • Volume 6 Number 1

A

B

E

C

D

F

I

H

K

G

J

Thinking About 

Science

To discover new things, 

scientists must work with 

information. They may take 

old information and look at it in 

new ways. They may collect new information 

and consider it in ways that no one has done 

before. Often, the information that scientists 

collect and consider is in the form of numbers. 

The numbers represent quantities of whatever 

it is the scientists are studying. 

In this study, the scientists were interested 

in carbon dioxide, or CO2

. The scientists 

estimated the amount of CO2

 absorbed by 

urban trees. They compared that number with 

another number. The other number indicated 

how much CO2

 was put into the atmosphere 

when machines were used to plant and 

maintain urban trees. Thus, they were looking 

at how much CO2

 was either being absorbed 

or emitted by planting and maintaining urban 

trees. By using numbers, the scientists could 

better understand how the management of 

urban trees affects the carbon cycle. 

Thinking 

About the 

Environment

Carbon is one of the most 

interesting and widespread of 

elements. All plants and animals 

on Earth, including humans, are made up of 

carbon. Much of Earth’s carbon is held deep in 

Earth as petroleum, coal, and natural gas. These 

forms of carbon are used by humans as fossil 

fuels to run machinery. 

In the carbon cycle, carbon moves from the 

atmosphere, to Earth, into Earth, and back to 

the atmosphere (figure 1). When fossil fuels are 

burned in engines, carbon is taken from inside 

the Earth and then emitted into the atmosphere 

as CO2

. If humans did not burn fossil fuels, the 

carbon cycle would stay in a natural balance. 

Too much CO2

 in the atmosphere disrupts 

Earth’s climate and can cause the Earth’s global 

temperature to rise. 

Figure 1. The carbon cycle.

Carbon is emitted by:

A Volcanic eruptions

B Forest fires

C Burning of fossil fuels

D Burning of fossil fuels

E Decomposers

Carbon is held on Earth by:

G Carbon in water

H Photosynthesis

I Carbon in soil

J Underground carbon

K Respiration F Atmospheric carbon
34 The Urban Forest Edition

Introduction

Too much carbon dioxide (CO2) in the 

atmosphere is mostly caused by two things: 

burning fossil fuels and the loss of trees. Fossil 

fuels are made up of carbon. When they 

are burned as fuel, the carbon is released in 

the form of CO2

. Trees absorb CO2 during 

photosynthesis. When trees are removed or 

die, their ability to absorb CO2

 is lost.

When people plant trees in urban areas, 

they expect the trees to do many things. 

Urban trees help to keep urban areas cooler, 

they hold soil in place, they make urban areas 

prettier, and they help to keep urban areas 

quieter. They also absorb CO2

 from cars, 

buses, and the many engines that are used in 

urban areas. When people think about the 

benefits of having urban trees, they often think 

of these things. There is also something that 

they may not think about. 

When people plant and maintain urban 

trees, they usually use machines with engines. 

These machines include trucks, chainsaws, 

and other machines (figure 2). As you know, 

these engines emit CO2

. When people think 

about how much CO2

 is absorbed by urban 

trees, they should also consider how much 

CO2

 is emitted from the engines used to care 

for the trees. When a tree is cared for using 

machines with engines, there is a point in 

the tree’s lifetime at which more CO2

 will be 

emitted from the engines than the tree has 

absorbed. The scientists wanted to know 

which tree species can grow the longest before 

reaching that point.

Figure 2. Urban trees are maintained using 

trucks and other machines that emit CO2.

Reflection Section

b Think about how a part of the carbon cycle 

is illustrated by urban trees and urban tree 

maintenance. With that in mind, what is the 

question that the scientists were trying to 

answer?

b Why do you think the scientists wanted to know 

which tree species absorb the most CO2

 over 

time?
35

The Natural Inquirer • Volume 6 Number 1

Method

The scientists thought about all of the ways 

that CO2

 is absorbed or emitted during the life 

of an urban tree. These included the growth 

of the tree, the engines that were used to plant 

and maintain the tree, and what happened 

to the carbon in the tree after the tree was 

removed at the end of its life (figure 3).

The scientists created 14 categories to 

describe the lifespan, growth rate, and size 

of urban tree species. The 14 categories were 

formed from some combination of tree species 

size, life span, and growth rate (figure 4). In other 

words, one category was a small tree with 

a short life span that grows slowly. Another 

category was a medium-size tree with a short 

life span that grows slowly. A third category 

was a small tree with a medium life span that 

grows slowly. By using different combinations 

of these three characteristics, the scientists 

created 14 separate categories.

The scientists studied one tree from each 

tree species for each of the 14 combinations 

of size, life span, and growth rate. They used 

existing information that estimated how much 

each type of tree would weigh every year of 

its life. From this estimate, they subtracted 

the estimated weight of the water in the tree. 

This gave the scientists a measurement of 

the weight of the dry matter in each tree. 

(Remember that scientists often put numbers 

on what they are studying.) To estimate the 

amount of carbon in the tree, they divided 

the weight of the tree’s dry matter by two. 

They divided by two because half of the dry 

matter of a tree is composed of carbon. The 

amount of carbon in the tree was considered 

equal to the amount of CO2

 that the tree had 

absorbed.

Each tree was maintained exactly alike. 

This included things like planting the tree, 

pruning the tree, bringing water to the tree, 

and removing the tree at the end of its life. 

The amount of fossil fuel used every year 

was recorded.The scientists used existing 

mathematical equations to estimate how much 

CO2

 was emitted from the engines.

Ways that CO2 is absorbed 

or is kept from being emitted Ways that CO2 is emitted

As a tree grows and gets larger with more leaves, 

more CO2 is absorbed.

Trucks and shovels with engines are used to plant 

the tree.

When a tree is removed and its wood is used for 

furniture or other items, its carbon is not emitted.

Chainsaws and trucks are used for pruning the tree’s 

branches and then chipping the branches into small 

chips for mulch. The engines emit CO2. As the mulch 

decomposes, it also emits CO2.

When a tree is removed and put into a landfill, only 

a small portion of its carbon is emitted.

Chainsaws and trucks are used to remove the tree at the 

end of its life. The tree may be chipped into small chips 

for use as mulch. CO2 is emitted when machines are used 

and when the mulch decomposes.

When a tree is planted in the right location 

around a building, it can shade the building to 

reduce energy use and CO2 emissions from power 

plants.

Figure 3. Ways that CO2 is absorbed and emitted during the life of an urban tree.
36 The Urban Forest Edition

The scientists now had two sets of numbers 

for each of 14 tree species for every year of each 

tree’s life. One set of numbers had to do with the 

carbon dioxide emitted every year by equipment 

used to maintain the tree. The other was a 

measurement of the amount of carbon absorbed 

by the tree every year. They compared these 

numbers to answer their question.

Findings

Trees species with a long life span and a 

moderate growth rate lived the longest before 

the CO2

 emitted from trucks, chainsaws, 

and other machines was greater than the 

amount of CO2

 that the trees absorbed. In 

general, the longer a tree lived, the better 

the balance between CO2

 absorption and 

emission. This is partly because of the large 

amount of CO2

 that is emitted by engines 

when a tree is planted or removed. It is also 

because trees that live longer are usually larger 

and have more leaves. This means that they 

photosynthesize more and, therefore, absorb 

more CO2

 than smaller trees. 

All living things exist on 

Earth because of the oneway flow of energy from 

the sun. Plants use sunlight 

to make sugars and starches 

from water and carbon 

dioxide, a process known as 

photosynthesis. Plants are 

eaten by animals, and some 

animals eat other animals. As 

plants and animals are eaten, 

their energy is transformed 

into energy that can be used 

by the one who is doing the 

eating. When plants and 

animals die, their bodies 

decompose, providing energy 

for microorganisms in the soil. 

Over time, much of 

Earth’s energy is held deep 

and in earth in the form 

of coal, petroleum, and 

natural gas. Although energy 

changes form, energy that 

comes from the sun cannot 

be created or destroyed by 

anyone or anything on 

Earth. ■

Thinking About Ecology

Size of tree 

species

Life span of 

tree species

Growth rate of 

tree species

Small Size 

(less than 40 feet)

Short 

(20 years)

Slow (less than12 

inches per year)

Medium Size 

(40-60 feet)

Medium 

(40 years)

Moderate (12-24

inches per year)

Large Size 

(greater than 

60 feet)

Long 

(60 years)

Fast 

( > 24 inches per 

year)

Moderate to Fast

Figure 4. Characteristics that were used to 

create 14 categories of urban tree species.

Reflection Section

b What did the two sets of numbers represent?

b Why do you think each tree was maintained 

exactly alike?
37

The Natural Inquirer • Volume 6 Number 1

FACTivity

As a class research project, create a 

list of different types of native trees for 

the area in which you live. In groups, 

research each tree and find out how long 

the tree lives and how fast it grows as 

well as leaf type, special characteristics 

of the tree, etc. Your group should make 

a presentation about your tree. After all 

of the presentations have been made, 

your class should vote on which type of 

tree to plant in your schoolyard. The tree 

should be successful in your particular 

schoolyard environment. 

Teachers—

A possible extension to this Factivity 

is to have students engage in a service 

learning project. After researching the 

trees and voting on type of tree to plant, 

students can go out into the community 

and find businesses that would be 

interested in helping to plant urban trees. 

Schools could get businesses to donate 

funds to buy trees appropriate for the 

area and the students could plant them. 

Implications

We often consider doing things without 

looking at the complete picture. The scientists 

in this study suggest that people should think 

carefully before selecting an urban tree species 

to plant. People should compare the amount 

of carbon that the tree will absorb with the 

amount of CO2

 being emitted when the tree 

is planted and maintained using machines. 

The scientists suggest that people should 

plant urban trees that live a long time and 

grow either fast or moderately fast. They also 

suggest that people use machines that are 

energy efficient, or they should do some of the 

things by hand. ■

Reflection Section

b This research identified the amount of CO2

emitted by equipment that was used to maintain 

urban trees. What might happen in the future to 

the design of the equipment used to maintain 

urban trees? How could that change affect the 

scientists’ research?

b If people want to increase the amount of CO2 that 

is absorbed in urban areas, should they plant 

more or fewer urban trees?

b Of the tree species characteristics in figure 4, 

which kind of species should they plant?

Reflection Section

b This study looked at how much CO2 was emitted 

by engines used to plant and maintain urban 

trees. What is one way that CO2 emissions could 

be reduced without changing the type of tree 

species being planted?

b This study examined the advantages and 

disadvantages of planting and maintaining 

different urban tree species for balancing CO2. 

What might be some other advantages and 

disadvantages of different tree species?

From Nowak, D. J., Stevens, J. C., Sisinni, S. M., and Luley, C. 

J. (2002). Effects of urban tree management and species 

selection on atmospheric carbon dioxide. Journal of 

Aboriculture, 28(3):113-122.
38 The Urban Forest Edition

Good to the 

Last Drip:

How Trees Help To 

Reduce Pollution
39

The Natural Inquirer • Volume 6 Number 1

Meet the Scientists

Dr. Ustin: 6 I have always thought that it was 

important to preserve our natural heritage

and wanted to work as an ecologist. Working 

with information collected from satellites has 

allowed me to view the environment from 

a large-scale perspective. It is a privilege to 

work on problems that have great benefit to 

society and to help improve the way we take 

care of our environment.

Dr. Xiao: 6 I enjoy working to discover the 

secrets of the natural environment, such as the 

interactions between water and the surrounding 

environment. My favorite experiences in 

science are when I find these secrets and then 

use them to improve our environment. With 

these discoveries, we can improve the quality 

of our lives and care for our natural resources. 

Future generations will benefit from our work.

Dr. McPherson: 6 My favorite science 

experience is seeing a paper finally in print 

or giving a presentation to a large group 

and sensing their interest and excitement. 

The process of planning and conducting 

research is long and painstaking. One 

has to be patient because results don’t 

come quickly. However, the joy of seeing 

a project completed and knowing that it is 

valued by others is very gratifying.

Dr. Simpson: 6 One of my favorite 

experiences in science was to participate 

in a meteorological field study in western 

Colorado. We camped out in the 

mountains. We flew on a helicopter to put 

some of our equipment on surrounding 

mountain ridges. We also had an 

opportunity to meet and work with other 

scientists from all over the United States.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing

Glossary:

heritage (hair uh tij): 

Something handed down 

from the past.

ecologist (e kol uh 

jist): A scientist who 

studies the relationships 

between living things and 

their environment.

meteorological (me te

or o loj uh kôl): Having 

to do with weather or 

climate.

intercepted (in tür 

sep ted): Stopped or 

interrupted. 

erosion (e ro shun): 

The process or state of 

wearing or washing away.

regulation (reg ya 

la shun): The act of 

controlling according to a 

system. 

equation (e kwa shun): 

A written statement that 

indicates the equality of 

two expressions.

species (spe sez): 

Groups of organisms that 

resemble one another 

in appearance, behavior, 

chemical processes, and 

genetic structure.

aerial (air e ul): Of or in 

the air.

deciduous (de sij oo us): 

Shedding its leaves every 

year; not evergreen.

Pronunciation Guide

Accented syllables are 

in bold.
40 The Urban Forest Edition

Thinking About 

Science

One of the best things about 

science is that scientists will never 

learn everything. Even when 

scientists are pretty sure of 

something that they’ve learned, 

new information may cause 

them to revise their thinking. 

Scientists, therefore, will never run out of new 

things to study! In this research, the scientists 

wanted to know how much rainfall is intercepted

by trees growing in urban areas. In the past, 

other scientists had estimated how much rainfall 

was intercepted by trees growing in rural areas. 

Since urban areas and rural areas are different, 

the scientists in this study felt that urban trees 

should be studied separately. When this study 

was finished, do you think that the scientists 

knew everything about rainfall interception by 

urban trees? Why or why not?

Thinking About the 

Environment

Natural systems are organized so 

that the environment will remain 

balanced. For example, when 

there is a lot of rainfall and few 

trees in an area, the rainfall can 

cause soil erosion and might 

cause flooding. When trees 

are growing in an area, the leaves, branches, 

trunk, and roots help to reduce soil erosion 

and flooding. Rain falls on the tree, where 

it is stopped or slowed down. Roots absorb 

water for the tree’s use. The trees are a form 

of control that helps to protect the soil from 

erosion and the area from flooding. In natural 

areas that have a lot of rain, you will find a lot 

of trees. You can find this kind of regulation in 

all natural systems, including your own body! 

Can you think of one way that your body 

keeps your own amount of water balanced?

Figure 1. Storm drains.

Introduction

Urban areas are different than rural areas. 

In urban areas, there are many more human 

structures and activities that are sources of 

pollution. When it rains, the rainfall washes 

the pollution from lawns, streets, sidewalks, 

and other surfaces. Water is carried from city 

streets through stormdrains and pipes that 

eventually lead to our streams and rivers (figure 

1). If too much rain falls at one time, these pipes 

can get backed up and cause flooding. 

Trees help to slow the amount of rainfall 

entering storm drains. The rainfall is stopped 

or slowed down by leaves, branches, and the 

trunk of trees. Some of the rain evaporates 

off of the leaves and branches before it can 

reach the ground (figures 2 and 3). The 

roots of trees also absorb some of the rain. 

This keeps even more of the water from 

going down the stormdrains. 

In the past, scientists had estimated how 

much rainfall is intercepted by trees growing in 

rural areas. The scientists in this study wanted 

to know how much rainfall is intercepted by the 

trees that grow in an urban county in California. 
41

The Natural Inquirer • Volume 6 Number 1

Figures 2 and 3. The leaves on trees intercept 

some of the rainfall. 

Method

The scientists developed two equations. The 

equations helped the scientists to identify what 

they needed to measure to find out how much 

rainfall is intercepted by a tree. Using symbols, 

the equations describe that when rain falls on 

a tree, it stays for a short time on the tree’s 

leaves, branches, and trunk. Then, the rain 

water either runs down these surfaces, drips 

to the ground, or evaporates. Here are the 

two equations:

1. Rainfall Interception = L + E 

2. Rainfall Interception = R – TH – F – D

 

Here is an explanation of the symbols.

L = The amount of rain that stays on 

leaves and branches.

E = The amount of rainfall that 

evaporates from leaves and branches.

R = The total amount of rain falling on 

the tree.

TH = The amount of rain that falls 

through the tree without hitting any 

leaves or branches.

F = The amount of rain that drips down 

the stems and trunk.

D = The amount of rain that drips from 

leaves and branches.

First, try to read these equations yourself using 

the explanation of the symbols. 

This is how to read the equations:

Equation 1: The amount of rain that is 

intercepted by a tree is equal to the amount 

of rain that stays on the tree’s leaves and 

branches plus the amount of rain that 

evaporates off of the leaves and branches. 

Equation 2: The amount of rain that is 

intercepted by a tree is equal to the total 

amount of rain falling on the tree minus 

the amount of rain that falls through the 

tree without hitting any leaves or branches, 

minus the amount of rain that drips down 

the stems and trunk, minus the amount of 

rain that drips from leaves and branches.

Reflection Section

b What is the question that the scientists were 

trying to answer?

b Do you think that the amount of rainfall being 

intercepted by trees is different in urban areas 

than rural areas? Why or why not?
42

The Urban Forest Edition

In other words, any rain that reaches the 

ground underneath a tree has not been 

intercepted by the tree.

The scientists needed to determine how 

much rain is intercepted by various species of 

urban trees. They also needed to know how 

much rain is intercepted by different tree 

species during different weather conditions. 

For example, some rains are gentle and 

some are hard. Sometimes there is wind and 

sometimes the air is still. Rainfall can occur 

for a short period or a long period of time. 

Then, the scientists needed to determine two 

more things. They needed to know which tree 

species, and how many of each, were growing 

in the county. They discovered these two 

things using aerial photography and by walking 

around and actually looking at the trees. 

The scientists calculated how much rainfall 

is intercepted by different tree species during 

different rainfall conditions. They knew how 

many trees of different species were growing 

in the county. They looked at weather 

records. This allowed them to determine what 

kinds of rain storms occurred in the past and 

in what season they occurred. With all of this 

information, they were able to estimate how 

much rain was intercepted by all of the trees 

growing within the county.

Findings

The scientists expressed the amount of 

rainfall interception in two ways. First, they 

calculated the percentage of rainfall that was 

intercepted only in the areas where trees were 

growing in the county (figure 4, area A). 

Then, they calculated the total percentage of 

rainfall that was intercepted by trees across 

all of the land in the county (figure 4, areas 

A+B). They reported the total amount of 

rain that was intercepted over the entire year. 

They found that 11 percent of the rain that fell 

directly on trees was intercepted (figure 4, 

area A). Across the entire county, including 

areas where there were no trees, 1 percent 

Nature has a way of 

taking care of itself. For 

example, most systems in 

nature are self-regulating. 

This means that although 

things may fluctuate, the 

systems in nature keep things 

pretty even. This idea is 

demonstrated in this study 

by the idea of rain and trees. 

If there are few trees and a 

lot of rain in an area, the rain 

can wash soil into streams 

and rivers. In natural areas 

where there is a lot of rain, 

however, there are usually 

a lot of trees. The leaves on 

the trees help to slow the 

rainfall, and trees absorb the 

rain water, which protects 

the soil. Where there are a 

lot of trees (like in a forest), 

the leaves or needles that 

fall create a spongy forest 

floor that absorbs rain 

water. When nature is left 

undisturbed, things work 

together to keep the system 

stable. ■

Thinking About Ecology

Reflection Section

b How did the equations help the scientists 

to answer their question? 

b Why did the scientists need to know which tree 

species were growing in the county?
43

The Natural Inquirer • Volume 6 Number 1

Reflection Section

b Why do you think it is important to calculate 

the amount of rain intercepted over the entire 

county, and not just where trees were growing? 

b Why do you think that deciduous trees 

intercepted less rain than evergreen trees? 

(Hint: The scientists collected information for an 

entire year.)

Figure 4. Areas that are under the tree 

canopies (A) and areas that are in the open (B).

of the rain that fell was intercepted by trees 

(figure 4, area A+B). Deciduous trees 

intercepted less rain than evergreen trees. 

Implications

Evergreen trees intercepted more rain 

than deciduous trees. This was partly 

because most of the rainfall in that county 

occurs in the winter. In some areas of the 

country, most of the rainfall occurs in the 

summer. In those areas, deciduous trees 

would be much more important as rainfall 

interceptors. Urban trees are helpful in part 

because they reduce the amount of rain 

hitting the ground, so they help to reduce 

the amount of pollutants and the amount of 

soil being washed into streams and rivers. ■

Reflection Section

b We need to have a certain amount of rain hitting 

the ground, but how can too much rain hitting 

the ground at one time be a bad thing? 

b What is one way that people living in urban 

areas can reduce the impact of rainfall on soil 

erosion?

From: Xiao, Q, McPherson, E. G., Simpson, J. R., and Ustin, S. 

L. Rainfall interception by Sacramento’s urban forest. Journal 

of Aboriculture 24(4):235-244.

B A B A B A B
44

The Urban Forest Edition

FACTivity

In this FACTivity, you will work with 

equations using symbols. 

Write the statements below as 

equations using symbols, and then write 

what each of the symbols means. See the 

example below.

Example: The number of ears in a 

classroom is equal to the number of 

warm-blooded animals in the classroom 

times two.

E = A x 2

E = The number of ears in a classroom.

A = The number of warm-blooded 

animals in a classroom.

1. The area of sunshine reaching the 

roof of a house is equal to the total area 

of the roof, minus the area of the roof 

that is not receiving sunshine.

2. The total number of miles of streams 

in the United States is equal to the 

number of miles of streams in each 

State multiplied by the number of 

States.

3. The number of candybars in a middle 

school at 6 p.m. is equal to the number 

of candybars in the candy machine, plus 

the number of candybars brought to 

school by people, minus the number of 

candy bars eaten by 6 p.m.

As a class, see if you can develop 

more equations based on things that you 

see around you or topics that you are 

studying. You can get into small groups 

and hold a contest to see which group 

can come up with the most true equations 

within a time limit. 

Use your imagination! Using the 

equation below, write out your own 

statement of what it might represent. You 

can do this in small groups and share your 

equation with the rest of the class.

N = I + M1 + M2 – W – C
45

The Natural Inquirer • Volume 6 Number 1

Don’t Be So 

Fuel-ish!

How Much Fuel Is 

Saved When Cars Are 

Parked in the Shade?
46 The Urban Forest Edition

Thinking About 

Science

Scientists sometimes design their 

experiments so that they can 

compare different things. In 

this experiment, the scientists 

wanted to explore some of the 

differences between parking lots 

that are shaded and parking lots 

that are not shaded. When scientists compare 

different things, they carefully identify what 

is similar about and different between the 

things. (What do you think is similar about 

and different between these two parking 

lots?) Scientists then take the same kind of 

measurement from each thing to see if there 

are differences. In this study, the scientists 

were interested in the temperature of each of 

these two areas.

Meet the Scientists

Dr. Scott: 5 The 

most fun I’ve had as a 

scientist was the time 

I operated a “cherry 

picker” truck to lift a 

colleague and I up to 

the top of some pine 

trees. We were trying 

to collect some gases 

emitted from pine 

needles. The truck was 

the type you might see a 

technician use to reach 

telephone lines. We 

stood cramped together 

inside the “bucket” with 

our scientific equipment. 

It was hilarious. But the 

view from the tree tops 

was great.

Dr. Simpson: 5

One of my favorite 

experiences in science 

was to participate 

in a meteorological

field study in western 

Colorado. We camped 

out in the mountains. 

We flew on a 

helicopter to put some 

of our equipment on 

surrounding mountain 

ridges. We also had an 

opportunity to meet 

and work with other 

scientists from all over 

the United States.

Dr. McPherson: 5 

My favorite science 

experience is seeing a 

paper finally in print or 

giving a presentation 

to a large group and 

sensing their interest 

and excitement. The 

process of planning and 

conducting research is 

long and painstaking. 

One has to be patient 

because results don’t 

come quickly. However, 

the joy of seeing a 

project completed 

and knowing that it is 

valued by others is very 

gratifying.
47

The Natural Inquirer • Volume 6 Number 1

Glossary:

meteorological (me te or o loj uh kôl): 

Having to do with weather or climate.

emit: (e mit): To throw out or eject.

climate (kli met): The average condition of the 

weather over large areas, over a long time, or 

both.

data (dat uh): Facts or figures studied in order 

to make a conclusion.

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing

Thinking About the 

Environment

Cars use petroleum as a fuel 

that runs their engines. When 

the fuel is burned, its energy 

is transformed into hot gases 

that leave the car through the 

tailpipe. The form of the energy 

in liquid petroleum is different than the form 

of the energy that comes through the tailpipe. 

None of the energy is destroyed in the burning 

process, but it is more spread out and less 

useable. Burning petroleum as a fuel is an 

example of the First Law of Energy. This 

law states that energy cannot be created or 

destroyed. No matter what kind of energy you 

can think of, it has to obey this law!

Introduction

You probably know that most of the 

dangerous gases that come from cars come 

from the tailpipe while the engine is running. 

Did you know that cars still produce some 

gases while the engine is turned off? Parked 

cars produce more of these gases when the air 

temperature is hotter than when it is cooler. 

The scientists in this study wanted to know 

if cars parked in shady parking lots emit fewer 

gases than cars parked in sunny parking lots. If 

that is the case, it would give people another 

reason to plant trees in parking lots, especially 

where the climate is hot.

Figure 1. The location of Davis, California

Method

 The scientists parked two identical cars in 

a parking lot in Davis, California (figure 1). 

One of the cars was parked in the sun. The 

other was parked in the shade (figure 2). 

The scientists parked the cars facing the same 

direction. They tried to make both of the 

parking spaces exactly the same, except for 

the amount of sunlight hitting each of the cars. 

In the shady parking space, the scientists 

measured the percentage of the sky that was 

visible when looking up through the tree. In 

Reflection Section

b Why do you think hotter temperatures cause 

more gases to be emitted from parked cars?

b What is the question that the scientists were 

trying to answer? North
48 The Urban Forest Edition

Figure 4. The scientists collected data under different amounts of shade.

Figure 3. The instruments collected the data 

automatically.

both parking spaces, here are the things that 

they measured:

1. The outside temperature

2. The amount of energy coming from the 

sun (solar radiation or solar energy)

3. The car’s inside temperature

4. The car fuel tank’s temperature 

The scientists collected this information 

from August 5 to August 10 when the 

climate is hot in Davis, California. They used 

instruments to collect the data automatically 

every 5 minutes (figure 3).

Figure 2. The cars parked in the parking lot. 

The cars were dark metal-flake blue 1996 

Chevrolet Corsicas.

To determine how much dangerous 

gases were coming from the parked cars at 

different temperatures, the scientists used 

mathematical equations that had already been 

developed. These equations estimated how 

much gas would evaporate from a parked car 

at different temperatures. The scientists used 

a computer to do the calculations, using the 

temperature data that they collected. The 

scientists estimated the differences in the 

amount of evaporating gas under different 

amounts of shade over the car (figure 4). The 

scientists also compared the cars’ surfaces and 

inside temperatures, fuel tank temperatures, 

8% Shade Cover 25% Shade Cover 50% Shade Cover
49

The Natural Inquirer • Volume 6 Number 1

Thinking About Ecology

Table 1. Temperature differences in the shady and the 

sunny parking spaces.

Temperatures

for Aug. 5-7 

Shady Parking

Lot  ̊C

Sunny Parking

Lot  ̊C

Average Afternoon 

Air Temperature 39 40

Average Afternoon 

Temperature 

Inside Car

 50 65

Average Maximum 

Fuel Tank 

Temperature

 38.6 41.6

and the amount of the sun’s energy reaching 

each car.

Findings

The temperature was warmest from 

August 5-7. Table 1 shows the differences 

in temperatures in degrees Celsius on the 

warmest days. (To calculate the degrees in 

Fahrenheit, multiply the temperature by 9/5 

then add 32).

 Only 20 percent of the amount of solar 

energy reaching the car in the sunny parking 

space reached the car in the shady space. 

From the data in Table 1 and this information 

on the amount of solar energy reaching 

the cars, the scientists concluded that the 

reduction in temperature in the shady parking 

All living things have 

environmental limits beyond 

which they can no longer 

survive. People, for example, 

cannot survive long without 

air, water, or in temperatures 

that are either too low or 

too high. In this article, the 

scientists measured the 

temperature inside of cars 

that were parked in the 

sun and in the shade. The 

internal temperature of the 

car parked in the sun was 

150

C higher or 270F higher 

than the car parked in the 

shade. Even so, the car 

parked in the shade, with 

the windows rolled up, had 

a temperature of 500

C or 

1220

F. At this temperature, 

living things such as people 

and dogs cannot live for 

very long. In this article, the 

scientists were concerned 

about dangerous gases 

evaporating from cars. Do 

you think that these gases 

have something to do with 

environmental limits? Why or 

why not? ■

Reflection Section

b Why do you think that the scientists used 

identical cars?

b Why do you think that the scientists collected 

their information when the climate was hot?
50 The Urban Forest Edition

space was due to the lower amount of solar 

energy under the tree. 

The amount of gas evaporating from the 

car in the shady parking space was only 2 

percent less than from the car in the sunny 

space. The scientists reported that if the 

amount of shade over parking lots was 

increased from 8 percent to 50 percent, the 

amount of gas evaporating from parked cars 

would be reduced by 2 percent.

Implications

A 2-percent reduction in evaporation from 

cars parked in the shade does not seem very 

large. However, this amount is equal to the 

amount of fuel that could be saved if printing 

presses, hospitals, and waste-burning and 

car scrapmetal businesses throughout the 

county updated their fuel-burning equipment. 

Sometimes, just a little bit of improvement can 

be very important.

The scientists caution that the costs and 

benefits of planting trees in parking lots 

need to be determined. It takes money, fuel, 

equipment, and time to plant and take care 

of trees. Falling leaves, birds droppings, and 

falling branches are other things to consider. 

On the other hand, trees in parking lots keep 

cars cooler, protect the pavement, protect 

people from the sun’s harmful rays, absorb 

air pollution, soak up rainwater, reduce the 

amount of gases evaporating from cars, and 

Reflection Section make the parking lot more attractive. ■

b From the information in Table 1, would you say 

that the amount of sunlight reaching a parked 

car has an impact on its inside temperature?

b Do you think that a 2-percent difference is a very 

big difference in the amount of gas evaporating 

from a car? Why or why not?

Reflection Section

b Which would you prefer–a parking lot 

with trees or one without trees? Why?

b Do you think that evaporation from cars will 

continue to be a problem in the future? Why or 

why not?

From Scott, K., Simpson, J. R., and McPherson, E. G. (1999). 

Effects of tree cover on parking lot microclimate and vehicle 

emissions. Journal of Aboriculture 15(3):129-142.
51

The Natural Inquirer • Volume 6 Number 1

Sample observation chart

 

Jar in Sun—

Temperature 

Jar in Sun—

Amount of water 

Jar in Shade—

Temperature 

Jar in Shade—

Amount of Water

Day 1 Day 2 Day 3 Day 4 Day 5

FACTivity

In this FACTivity, you will 

answer the question: What is the 

relationship between temperature, the 

amount of visible sunlight, and the amount 

of water evaporating from two identical 

glass jars?

 Get two identical glass jars. Mark each 

of them with a permanent marker at 1/8-

inch intervals from 1/8 to 1 inch from the 

bottom of the jar. Fill the jars with water to 

the 1-inch mark. Place them on a window 

sill that receives at least 3 hours of full 

sun. Place branches of leaves (or pine 

boughs) near one of the jars so that it is 

shaded throughout the day.

 Get two thermometers. Place them 

beside the jars. Make sure that the 

thermometer beside the shaded jar is also 

shaded.

 Every day for 1 week during the sunny 

time of the day, check the temperature of 

each jar and the amount of water in the jar. 

Make a record of your observations. Create 

a chart for your observations. At the end 

of the week, compare the temperatures 

of the two jars and the amount of water in 

the jars for the entire week. Create two bar 

charts. One bar chart should display the 

temperature of the two jars for each day. 

The second bar chart should display the 

amount of water in each jar for each day. 

See the following example.

Discussion–

What is the relationship between the 

temperature, the amount of sunlight 

reaching the jar, and the amount of 

evaporation? Where did the water go? 

Which jar of water evaporated faster? 

Why? How is this experiment like the 

evaporating gas? Where does the gas 

go? Does the gas or the water lose their 

energy when they evaporate? 

Day 1 Day 2 Day 3 Day 4 Day 5

80

70

60

50

40

Legend

Jar in sun

Jar in shade

Temperature

in degrees F
52 The Urban Forest Edition

Yard Sale!

How Trees Affect the 

Selling Price of Houses
53

The Natural Inquirer • Volume 6 Number 1

Meet the Scientists

Dr. Cordell: 6 My most memorable and rewarding science 

experience came early in my career. It was the publication in 

a science journal of an article that I had written. The article 

was based on my dissertation research about urban forests. 

My research was about estimating the value of urban green 

spaces, including trees and forests in urban areas. It was a 

thrill to see my name on an article in a science publication. 

It was also great to get praise for my work from a person I 

greatly admired and respected.

Dr. Bowker: 5 My 

favorite science 

experience is using 

what I learned in 

school to help solve 

problems related to 

people and nature.

Mr. Sydor: 5 My 

favorite science experience 

is walking the road from 

knowing little about 

a specific problem to 

knowing almost everything. 

I also enjoy being able to 

apply the knowledge that I 

learned from textbooks to 

real-life situations.

Dr. Newman: 5 My 

favorite science 

experience is 

discovering new 

things that help 

people to protect our 

environment and our 

natural resources.

Thinking About 

Science

What does the price of 

something represent? To 

economic scientists, the price 

of something represents its value 

to people. Economic scientists conduct a 

type of science called economics. Economics 

is the study of the way in which goods and 

wealth are produced, distributed, and used in 

a society. This can include any good, including 

ones that you normally would not think of as 

being bought and sold. 
54 The Urban Forest Edition

In this study, the scientist wanted to 

discover the value of trees growing in the yard 

around a house. Why do you think that it is 

important to know the value of trees growing 

around a house? Do you think that the value 

of something is reflected by its price? Why or 

why not? Think of something from this week’s 

news that shows how the price of something is 

related to its value to people.

Figure 1. A yard with trees surrounding a 

house.

Thinking 

About the 

Environment

When people decide to buy a 

house, they have a lot of things 

to consider. They have to think 

about how many bedrooms and bathrooms 

they need. They have to think about where 

the house is located. For example, is it close to 

any schools or shopping, or to the bus stop? 

They have to think about how much they can 

afford to pay. One of the things that may be 

important is the amount of the yard that is 

shaded by trees. 

Usually, when people think about the 

environment, they think about things like 

forests, lakes, or oceans. The environment also 

surrounds your home. It is important to think 

about the environment that surrounds your 

home, as well as the environment that might 

be far away.

Introduction

People who own houses usually have a 

yard that surrounds their house (figure 1). 

The yard might be big or small. It might not 

have any trees, or it might have a lot of trees. 

For people who have trees surrounding their 

Glossary:

natural resource (na cha rôl re sôrs): A supply 

of something in nature that takes care of a 

human need, such as oil.

dissertation (dis u ̈r ta shun): A written essay, 

usually written by someone earning a Doctor of 

Philosophy degree.

economic (e ko nom ik): Having to do with the 

management of money. 

habitat (hab uh tat): Environment where a plant 

or animal naturally grows and lives.

indicator (in di ka tôr): Something that measures 

or shows something.

average (av rij): The usual kind or amount. The 

number gotten by dividing the sum of two or 

more quantities by the number of quantities 

added.

canopy (kan uh pe): Anything that covers like a 

roof. On a tree, the area of leaves that cover the 

ground.

aerial (air e ul): Of or in the air.

equation (e kwa shun): A written statement that 

indicates the equality of two expressions.

relationship (re la shun ship): When two or more 

things are connected in some fashion.

Pronunciation Guide

Accented syllables are in bold.

a as in ape

ä as in car

e as in me

i as in ice

o as in go

ô as in for

u as in use

ü as in fur

oo as in tool

ng as in sing
55

The Natural Inquirer • Volume 6 Number 1

house, the trees provide many benefits. The 

benefits include privacy, shade, habitat for 

birds and other wildlife, and beauty. 

If people value the benefits provided by 

trees growing around a house, they might 

be willing to pay more money to purchase 

a house that has trees growing in its yard. 

The scientists in this study were interested 

in knowing whether the benefits provided 

by trees are valued by people buying a new 

house. They also wanted to know how much 

money those benefits are worth.

Figure 2. Aerial photographs were used to 

determine the amount of tree cover in a yard. 

Photo courtesy of Barrow County, Georgia.

Method

The scientists decided to use the selling 

price of houses as an indicator of the value of 

trees surrounding a house. They collected 

information about houses that had been sold 

during a 3- year period. If a house had a lot 

size larger than 3 acres, they did not include 

it. (How many hectares is equal to 3 acres? 

Multiply by .405 to find out.) The lot size 

is the area of the yard plus the area that 

the house and other buildings take up. The 

scientists collected the following information 

about each house:

1. Selling price

2. Total amount of heated space in the 

house

3. Number of rooms and bathrooms in the 

house

4. Whether or not the house had brick 

construction 

5. Whether or not the house had an outside 

porch

6. Age of the house

7. Size of the lot

8. Average price of land in the neighborhood

9. Year of the sale

10. Amount of tree cover (the percentage of 

the lot covered by tree canopies)

Tree cover is the percentage of the total 

lot size that was covered by the canopies of 

trees. The scientists collected this information 

using aerial photographs (figure 2). They used 

an aerial photograph of every house and yard 

included in the study. On each photograph, 

they placed a 1-centimeter (cm) X 1-cm grid 

(figure 3). (How much is this in inches? 

Multiply 1 X .394 to find out.) They estimated 

the percentage of the entire lot size that was 

covered by trees. The scientists collected this 

information for 272 houses in Athens-Clarke 

County, Georgia (figure 4).

Reflection Section

b What questions were the scientists trying to 

answer?

b If you were the scientist, how would you 

determine how much money trees are worth to 

people buying a new house?

b The first paragraph of the “Introduction”section 

lists some benefits that are provided by trees 

surrounding a house. Name two other possible 

benefits.
56 The Urban Forest Edition

Figure 3. Aerial photograph with the grid 

placed over it. Photo courtesy of Barrow 

County, Georgia.

Figure 4. Location of Athens-Clarke County, 

Georgia.

The scientists then used the following 

equation for every house studied:

 Selling price = amount of heated space 

+ number of rooms and bathrooms + brick 

construction + outside porch + age of house + 

lot size + average price of land + year of sale + 

percentage of lot size covered by trees

 The scientists put the values for each 

house into the equation. They put all of the 

information into a computer. A computer 

program was used to determine how much 

each of the features, such as the number of 

bathrooms, affected the price. Using this 

method, the scientists were able to determine 

how much the percentage of tree cover 

affected the price of the houses.

Reflection Section

b Why do you think that the scientists collected 

information about the number of rooms, the 

amount of heated space, and other things for 

each house they studied?

b Do you think that the percentage of tree cover 

on a lot affected the price of the houses? Why or 

why not? North

All living things exhibit 

behavior. Behavior is the 

response of an organism to 

something in its environment. 

Usually, organisms behave so 

that their chances of survival 

are increased. If their survival 

is not in danger, organisms 

will usually behave in a way 

that increases their benefit. 

For humans, the definition 

of what is beneficial might 

vary from person to person. 

In this research, the behavior 

of humans is demonstrated 

by their purchase of a house. 

People will buy a house based 

on which house is thought 

to be most beneficial for the 

amount of money they are 

able to spend. The scientists 

were interested in the amount 

of tree cover surrounding a 

house. They wanted to know 

if tree cover was considered 

beneficial by people buying 

houses. If tree cover was 

considered beneficial, it 

would influence the behavior 

of people when they chose 

which house to buy. ■

Thinking About Ecology
57

The Natural Inquirer • Volume 6 Number 1

Figure 6. Location of trees on the lots.

Figure 5. The average lot had almost 60 

percent tree coverage.

Figure 7. The average value of different size 

trees.

Findings

Of the 272 houses studied, the average 

house was 46 years old and had 6 rooms 

and 3 bathrooms. The average selling price 

was $122,267. The average lot size was 0.65 

acres. (How many hectares is that? See the 

“Method” section to calculate the size in 

hectares.) The average price of the lot was 

$91,428 per acre. (Calculate the price of the 

lot for the average house in this study. To do 

this, multiply the price of the lot per acre times 

the average lot size.) The average lot had 

almost 60 percent tree coverage (figure 5). 

Most of the trees are on the border of the lot 

or in the backyard (figure 6). 

The scientists found that trees make a 

difference in the selling price of a house. For 

every 1-percent increase in the amount of 

tree cover, the selling price of a house was 

increased by almost $300. If the amount of 

tree cover was increased by 10 percent, the 

average price of a house was increased by 

almost $3,000. The scientists also calculated 

the average value of different size trees for the 

272 houses in this study (figure 7). 

40% 60%

$29

$211

$566

$1,066

6’ 16’ 26’ 36’

Front Yard
58 The Urban Forest Edition

 Implications

This study provides an estimate of the 

value of the trees that surround a house. It 

indicates what people are willing to pay for 

different percentages of tree cover when they 

buy a house. The study shows that trees are 

a positive feature of houses, and that people 

will pay more for a house if there is more tree 

cover on the lot. ■

From Sydor, T., Newman, D. H., Bowker, J. M., & Cordell, H. 

K. (2004). Trees in residential landscapes: Comparison of 

empirical data from two southern states. Presented at 2004 

Southern Forest Economist Workshop, St. Augustine, FL, 

March 14-16.

Reflection Section

b Think about how you feel about trees. Now 

pretend that you are getting ready to buy a 

house. Do you think that you would be willing to 

spend more money to buy a house that had more 

trees growing in its yard? Why or why not?

Reflection Section

b Why do you think that most of the trees were 

growing on the border of the lots or in the 

backyard?

b Athens-Clarke County is located in the 

Southeastern United States, where there is plenty 

of rain. Do you think that the amount of tree 

cover would affect the selling price of houses 

in other areas of the United States? Why or why 

not?

b Look at figure 7. What is the relationship

between tree size and the value of a tree?
59

The Natural Inquirer • Volume 6 Number 1

FACTivity

The question you will answer

 with this FACTivity is: According to your 

own research, do your findings support the 

findings of this study? The method you will 

use to answer this question is given below.

Students—

Take three sets of six photographs 

home and poll three adults. For each set 

of six photographs, have each adult place 

the photographs in order of preference, 

from their first choice to their last choice. 

Ask the adult to make his or her selection 

based on which house he or she would 

pay the most to buy to which house that 

he or she would pay the least to buy. Ask 

the adult to write on the back of each card 

what influenced him or her to rank that 

particular house in the order that he or 

she did. Record the rank order, from 1-6, 

on the front of each set of six cards.

 Bring your cards back to class to be 

analyzed with your classmates’ cards. 

After the results have been recorded on 

the board, count the number of times 

each photograph was ranked number 

1, number 2, number 3, etc., all the way 

to number 6. Based on the frequency of 

each ranking, identify, as a class, which 

photo was ranked overall the first choice 

(and most likely to bring the highest 

price) of the 6. Identify which photo was 

ranked the least favorite (and most likely 

to bring the lowest price). If possible, 

determine the overall rank order of all six 

photographs, based on the results of the 

polling. Read some of the reasons each 

house was placed in its order. 

Answer the question posed at the 

beginning of this FACTivity. Do the results 

of this research support the findings in this 

article? If they do, either House number 2 

or 5 should be the first choice overall, and 

House number 3 or 1 should be the last 

choice overall. 

As a class, discuss your research 

project. What were the reasons given 

for the choices made? How often did 

people mention the trees that surrounded 

the house? What might be some of the 

problems with the research? Other than 

the amount of tree cover surrounding 

the houses, what other things could have 

made people rank the photographs the 

way that they did? Think about things such 

as the way the houses looked, whether 

each student asked their questions in the 

same way, etc. 

Teachers—

Before the FACTivity, make three copies 

of the following page on cardstock for each 

student. Cut the cardstock to make three 

sets of six photographs. 

After the FACTivity, analyze the results 

in class. Appoint someone to record the 

answers on the board. Use the following 

form as a template. 

Rank order 1= first choice to 6= last 

choice.
60 The Urban Forest Edition

House Number 1 House Number 2

House Number 3 House Number 4

House Number 5 House Number 6
61

The Natural Inquirer • Volume 6 Number 1

 House 3

 10%

 Tree Cover 

House 1

20%

 Tree Cover 

House 6

30%

 Tree Cover 

 House 4

40%

 Tree Cover 

 House 5

50%

 Tree Cover 

 House 2

60%

 Tree Cover 

Number each photograph according to your choice

1 = first and 6 = last choice.

Student 1

Student 2

Student 3

Student 4

Student 5

Student 6

Student 7

Student 8

Student 8

Student 9

Student 10

Student 11

Student 12

Student 13

Student 14

Student 15

Student 16
62 The Urban Forest Edition

The follow section provides a guide to possible answers to the reflection questions found in 

each section of the articles. Reflection Sections 

are meant to stimulate critical thinking about the 

article, not to test knowledge. Use the answers 

below as a guide to stimulate critical thinking and 

discussion in your classroom. 

What You See Is Not What You Get:

Visible Sunlight and Ultraviolet Radiation in 

Urban Forests

Introduction

• What question did the scientists want to 

answer? The question was—Does the shade 

under urban trees protect people from the 

sun’s UVB radiation?

• Why is this question important? Because 

getting too much UVB radiation causes a lot 

of human health problems. If you think you 

are being shaded from UVB radiation but are 

not, then you might be unknowingly exposing 

yourself to danger from UVB radiation.

Method

• Name two reasons why is it important 

to find out what is already known about 

something before doing an experiment or 

collecting your own information about 

it. (1) You might conduct an experiment that 

discovers something that is already known, 

wasting your time and money. (2) If you know 

as much about something as possible, you will 

design a better experiment or research method. 

Your students may come up with many other 

reasons.

• From your own observation, would you 

say that leaves allow the sun’s visible 

radiation to pass through them? Why or 

why not? Leaves allow a little bit of the sun’s 

visible radiation to pass through them. You 

can tell this by looking up at the undersides of 

the leaves and seeing the light green color of 

the leaves that are in the sunlight. The light 

green color is caused by some of the sunlight 

penetrating the leaf ’s surface. Leaves that are 

shaded are a darker green color when viewed 

from underneath.

Findings

• Look at table 1 and read the paragraph 

below it. Put the scientists’ findings in 

your own words. This could be done many 

ways. Essentially, the findings show that when 

you think you are protected from UVB radiation because you are in the shade, you are 

actually not as protected as you think. It also 

means that when you are under a tree, you 

are receiving some protection from UVB 

radiation, even if you are in a sunny area under the tree.

• What do you think these findings mean 

for protecting yourself from harmful UVB 

radiation? If you are under a tree canopy and 

you can see around the tree canopy to part of the 

sky, you are not as protected from harmful UVB 

radiation as you think you are. You might want to 

take additional actions to protect yourself from 

UVB, such as use sun protection lotion.

 Implications

• In urban areas, some UVB radiation can 

be reflected off of buildings, sidewalks, 

streets, and fountains. Should you consider 

this source of UVB radiation when trying 

to protect yourself from the sun? Why or 

why not? Yes, because UVB radiation is the 

same, regardless of whether it is reflected from 

buildings and other objects in an urban area. 

• Reread the last sentence in the last paragraph above. Why do you think that you 

receive less UVB radiation when standing 

in the sun next to a tree than when standing in the sun away from a tree? When you 

are close to a tree, the tree’s crown blocks part 

 Reflection Section Answer Guide
63

The Natural Inquirer • Volume 6 Number 1

of the sky from which the UVB radiation comes. 

When you are farther from the tree, less of the 

sky is blocked and you receive more UVB radiation.

 

I’ve Got You Covered:

The Amount of Pavement Covered by Street Trees

Introduction

• What were the scientists trying to do in 

this study? They were trying to take an inventory of the amount of sidewalks and streets 

covered by street tree canopies.

• Can you think of two other items that 

you took an inventory of this past week? 

What were they? Examples of items that 

students could have taken an inventory of 

include—homework assignments; how many 

clean socks they had for the week; the number of CDs they have; and frozen foods in 

the kitchen freezer; which friends they were 

meeting after school. Your students should 

be able to think of many examples of taking 

inventories.

Method

• What do you think the numbers 10.7 meters and 35 feet represent? They represent 

the average width of the streets in that community.

• Do you think that the amount of tree 

canopy area covering streets and sidewalks was equal to the total amount of 

area that street tree canopies covered?

Why or why not? No, because the trees also 

covered front yards and median strips, and 

may have covered other things like planter 

boxes and even small buildings.

Findings

• Why do you think a greater percentage 

of sidewalk area than street area was 

covered by tree canopies? Because street 

trees are planted closer to sidewalks, and the 

area of street pavement is much greater than 

the area of sidewalk pavement.

• Did this tell the scientists how many benefits people were receiving from street 

trees? Why or why not? No, all the scientists know now is how much of the sidewalks 

and streets are covered by street tree canopies. They will have to do more research to 

estimate how much people benefit from this 

amount of tree canopy coverage.

Implications

• What is one reason it is important to 

know how much paved area street trees 

cover? In communities, people need to know 

how many trees to plant to achieve the 

amount of benefit that they hope to receive 

from urban forests. If you do not know how 

many trees or how much of the ground and 

pavement is now covered in trees, it is impossible to say whether you need more or not. 

Doing this inventory provides a starting point, 

or baseline, for understanding. This is an important point to make to your students, since 

in many situations, you must understand the 

baseline before you can discover more about 

the topic.

• Do you think it might be important to also 

estimate the amount of grassed areas that 

street trees cover? Why or why not? Yes, 

because street trees do more than keep areas 

cool. They also hold the soil in place and their 

roots absorb rainwater. They help to clean the 

air and provide homes for wildlife. The amount 

of area covered by tree canopies is a good measure of the total amount of trees growing in an 

area. If you know how much total area street 

trees cover, including grassed areas, you will 

have a more complete idea of the benefits being 

provided by urban trees.
64 The Urban Forest Edition

Social Groupies:

How Different Groups Use Urban Park

Introduction

•What is the question that the scientist 

wanted to answer? He wanted to know what 

kind of activities people of different ethnic backgrounds do when they visit an urban park.

•If you were the scientist, how would you 

learn what kind of activities people of 

different ethnic backgrounds do when 

they visit a park? Watch people when they 

visit a park and record what they do and what 

you think their ethnic background is. Talk to 

people of different ethnic backgrounds while 

they were visiting a park. Call people at their 

homes and ask them about their park activities. Students may come up with other ideas.

Method

• Why do you think that it was important 

to ask all of the visitors the same questions? Because if the visitors were asked different questions or the questions were asked 

in different ways, the answers could not be 

compared with each other.

• Based on your own experience, do you 

think that people from different ethnic 

backgrounds like to do the same things or 

different things when visiting an urban 

park? This is a personal question and has to 

be based on each student’s own experience. It 

provides an opportunity to discuss similarities 

and differences between ethnic groups, and 

misconceptions people can have about other 

groups of people.

Findings

• Are you surprised by the similarities and 

differences between the groups? Why or 

why not? Discuss with your class about 

whether you have observed the same 

things in your local parks. If your observations are different, how are they different? Why do you think that they are 

different? The answer to these questions 

will be based on the experiences and perceptions of your students. These questions should 

stimulate discussion about observation and 

about the differences and similarities between 

people of different ethnic backgrounds.

• When you visit a local park with others, 

how would you describe your group? Do 

you go with your family? With friends? 

What kind of things do you do when you 

visit a park? The answer to this question will 

be based on the individual experiences of your 

students. These questions can stimulate a discussion about the students’ use of local parks. 

Implications

• Why is it important to think about all of 

the users of urban parks? Because urban 

parks are managed for the use of all Americans, not just one ethnic group. This question 

provides a good opportunity to discuss the 

provision of public goods for all ethnic groups 

on an equal basis, including things like police 

protection, public schools, and any other public good or service. 

Balancing Act:

Urban Trees and the Carbon Cycle

Introduction

• Think about how a part of the carbon 

cycle is illustrated by urban trees and urban tree maintenance. With that in mind, 

what is the question that the scientists 

were trying to answer? Urban trees are a 

part of the carbon cycle because they absorb 

CO2

 from the air. Urban tree maintenance is a 

part of the carbon cycle because the engines 

emit CO2

 from the burning of fossil fuels. The 

scientists wanted to discover which trees absorbed the most CO2

 over the longest period of 

time. They wanted to find the point at which 

the engines used to plant and care for the tree 

emit more CO2

 than the tree is able to absorb.

•Why do you think the scientists wanted to 

know which tree species absorb the most CO2
65

The Natural Inquirer • Volume 6 Number 1

over time? Because these tree species will be the 

most beneficial to plant and maintain. They will 

cause less CO2 to be emitted over time.

Method

• What did the two sets of numbers represent? They represented (1) the amount of 

carbon in the tree and (2) the amount of CO2

that was emitted from engines used to plant 

and care for the tree.

•Why do you think each tree was maintained exactly alike? So that the scientists 

could compare the amount of carbon in each 

tree every year with the same amount of CO2

being emitted by the machinery used to maintain 

each tree. If the amount of CO2

 being emitted 

by machinery was different for each tree, the 

comparisons would be meaningless.

Findings

• This study looked at how much CO2 was 

emitted by engines used to plant and 

maintain urban trees. What is one way 

that CO2 emissions could be reduced 

without changing the type of tree species 

being planted? Trees could be planted and 

maintained without using machines, or the 

use of machines could be reduced. Also, more 

energy efficient engines could be used.

• This study examined the advantages and 

disadvantages of planting and maintaining 

different urban tree species for balancing 

CO2

. What might be some other advantages and disadvantages of different tree 

species? One thing to consider is whether there 

are nuts that could fall from trees. Another thing 

might be whether the tree is more or less likely 

to get a disease. Another thing to consider is 

how much water the tree needs or how much 

space it needs to grow. 

Implications

• This research identified the amount of 

carbon dioxide emitted by equipment 

that was used to maintain urban trees.

What might happen in the future to the 

design of the equipment used to maintain urban trees? How could that change 

affect the scientists’ research? We could 

have more energy-efficient machines that 

either emit less CO2 or use renewable sources 

of energy, such as hydrogen or solar power. If 

our equipment is more energy-efficient and 

emits less or no CO2, you would not have 

to think as much about the balance of CO2

absorbed by trees compared to the amount 

emitted by equipment. The scientists might 

not need to do this kind of research anymore.

•If people want to increase the amount 

of CO2 that is absorbed in urban areas, 

should they plant more or fewer urban 

trees? They should plant more trees.

• Of the tree species characteristics in figure 4, which kind of species should they 

plant? They should plant trees that live a long 

time and grow fast or moderately fast.

Good to the Last Drip:

How Urban Trees Help To Reduce Pollution

Introduction

•What is the question that the scientists 

were trying to answer? The question was—

How much rainfall is intercepted by trees growing in an urban county in California?

• Do you think that the amount of rainfall 

being intercepted by trees is different in 

urban areas than rural areas? Why or 

why not? Yes, because in a rural area, there 

usually are many more trees to intercept the 

rain. The trees grow differently in rural areas 

because they are not pruned. They are able 

to grow taller and closer together.
66 The Urban Forest Edition

Method

• How did the equations help the scientists to answer their question? The equations helped the scientists to identify what they 

needed to measure by defining exactly what is 

involved in rainfall interception, as well as what is 

not involved in rainfall interception.

•Why did the scientists need to know which 

tree species were growing in the county?

Because different kinds of trees have different 

shapes and sizes, different sized leaves, and different kinds and amounts of leaves. All of these 

differences will influence how much rainwater is 

intercepted by trees.

Findings

• Why do you think it is important to calculate the amount of rain intercepted 

over the entire county, and not just where 

trees were growing? The important thing is 

how much rainwater is going into stormdrains 

and into creeks and rivers. The rain falling all 

over the county has a potential to run into the 

drains and creeks, not just the rain falling over 

the trees.

•Why do you think that deciduous trees 

intercepted less rain than evergreen trees?

(Hint: The scientists collected information 

for an entire year.) Because deciduous trees 

lose their leaves in the winter, and evergreen 

trees keep their leaves and needles all year.

Implications

•We need to have a certain amount of rain 

hitting the ground, but how can too much 

rain hitting the ground at one time be a bad 

thing? Too much rain at one time washes pollutants and soil into streams and rivers.

• What is one way that people living in urban areas can reduce the impact of rainfall on soil erosion? They can plant and care 

for a larger number of urban trees.

Don’t Be So Fuel-ish!

How Much Fuel Is Saved When Cars Are 

Parked in the Shade?

Introduction

• Why do you think hotter temperatures 

cause more gases to be emitted from 

parked cars? When the temperature is hotter, more evaporation will occur. Evaporation 

can come from improperly connected hoses; 

from gas caps that are not sealed properly or 

have been lost; and from permeable, easily 

punctured, or deteriorating materials.

• What is the question that the scientists 

were trying to answer? Is there a difference in the amount of gases coming from cars 

parked in the shade vs. cars parked in the sun?

Method

• Why do you think that the scientists used 

identical cars? So that any differences they 

found in the car’s surface temperature, inside 

temperature, and gas tank temperature could 

be attributed to the air temperature and/or 

amount of solar radiation, not the type or 

color of the car.

• Why do you think that the scientists 

collected their information when the 

climate was hot? (1) If the temperature was 

cool, there would be less difference between 

the temperature in the sun and the shade, 

making it harder to identify any differences in 

measurement. (2) The amount of solar radiation would be different coming through trees 

in the summer than in the winter. 

Findings

• From the information in Table 1, would 

you say that the amount of sunlight 

reaching a parked car has an impact on 

its inside temperature? Yes, because the 

inside temperature was 15 degrees higher in 

the car parked in the sun than the one in the 

shade (in Fahrenheit, the temperature difference was 122o

 to 149o).
67

The Natural Inquirer • Volume 6 Number 1

• Do you think that a 2-percent difference is 

a very big difference in the amount of gas 

evaporating from a car? Why or why not?

Although 2 percent is not a very large amount, 

over the millions of cars parked every day, it 

could add up to a large amount of wasted and 

dangerous fuel being emitted into the air.

Implications

• Which would you prefer–a parking lot 

with trees or one without trees? Why?

This question can be used as a basis for discussion over the costs and benefits of urban 

trees.

• Do you think that evaporation from cars 

will continue to be a problem in the future? Why or why not? As cars become 

more fuel efficient and new fuel technologies 

are developed, evaporation from parked cars 

will probably become less of a concern. On the 

other hand, the millions of cars still being driven 

every day are getting older and, therefore, are 

more likely to have evaporation problems.

Yard Sale!

How Trees Affect the Selling Price of Houses

Introduction

• What questions were the scientists trying to answer? (1) Are yard trees valued by 

people buying a new house? (2) How much 

money are those benefits worth to people 

buying a new house?

•If you were the scientist, how would you 

determine how much money trees are worth 

to people buying a new house? Talk to different people who are buying a house and ask them 

how much more they would be willing to pay for 

a house with trees. Do some research about the 

price of similar houses with different amounts of 

trees growing in their yards. Your students may 

come up with other ideas. This is a good opportunity to brainstorm ways that your students might 

try to answer the scientists’ questions.

• The first paragraph of the “Introduction” section lists some benefits that are 

provided by trees surrounding a house. 

Name two other possible benefits. (1) 

Trees can be places for tree houses. (2) Trees 

can hold swings. (3) Trees might provide nuts 

or fruits that can be eaten. (4) Trees provide 

shady places to have picnics or just to sit and 

relax. (5) Trees can make the neighborhood 

quieter by absorbing sound. Your students may 

come up with other benefits. You can list them 

on the board and discuss the value of trees 

surrounding houses (and schools!).

Method

• Why do you think that the scientists collected information about the number of 

rooms, the amount of heated space, and 

other things for each house they studied?

The price may have also been affected by these 

other things. 

• Do you think that the percentage of tree 

cover on a lot affected the price of the 

houses? Why or why not? This is an individual question. It would depend on each 

student’s own assessment of the value of trees 

surrounding a house. This question could be 

used to stimulate discussion regarding how 

and why different people might or might not 

value trees.

Findings

• Why do you think that most of the trees 

were growing on the border of the lots or 

in the backyard? This is a question for which 

we do not have a definite answer, but some 

reasonable guesses are—(1) Trees are planted 

on the border of the property and in the backyard to provide privacy from next-door neighbors. (2) Trees are planted in the backyard for 

picnics, relaxing, tree houses, and other recreation. (3) Leaving the front yard open allows 

the house to be seen from the street. This 
68 The Urban Forest Edition

question can give you an opportunity to challenge students to think about why people who 

own houses plant trees where they do.

• Athens-Clarke County is located in the 

Southeastern United States, where there 

is plenty of rain. Do you think that the 

amount of tree cover would affect the selling price of houses in other areas of the 

United States?Why or why not? This question will allow you to discuss whether people 

buying houses in dry areas of the United States, 

such as New Mexico and Arizona, would spend 

more money on a new house if there were trees 

on the lot. It would also allow you to examine the 

practices and preferences of house buyers in the 

community where you live.

• Look at figure 6. What is the relationship 

between tree size and the value of a tree?

As a tree gets larger, its value goes up.

Implications

• Think about how you feel about trees. Now 

pretend that you are getting ready to buy a 

house. Do you think that you would be willing to spend more money to buy a house that 

had more trees growing in its yard? Why or 

why not? This is an individual question and every 

student will have a different answer. This question 

will give you an opportunity to discuss the findings 

and compare what the scientists found with your 

students’ own experiences and preferences.
69

The Natural Inquirer • Volume 6 Number 1

Schoolyard Tree Inventory and Biodiversity 

Project

Adapted from Web Site: Virginia Tech Biodiversity 

Study: http://www.cnr.vt.edu/dendro/forsite/si4.

htm

Subjects Covered

Science: Biology, Ecology

Math: Addition, multiplication, division, solving equations 

Reading: Comprehension

Science Skills: Observing, comparing, recording, classifying, analyzing

Science Education Standards Addressed: Abilities 

necessary to do scientific inquiry, Populations and 

ecosystems, Diversity and adaptations of organisms, 

Science as a human endeavor, Nature of science

Objectives:

1. Students will be able to observe, identify, measure, 

transform, and record data associated with trees.

2. Students will be able to analyze and synthesize collected data.

3. Students will be able to compare results and discuss 

results with peers.

Estimated Time for Lesson: 5 Class Periods

Materials:

Day 1: Plastic tags, wire, and permanent markers (You 

will need enough tags and wire to tag all of the trees 

and samples from each tree). Plastic bags for samples.

Day 2-3: Tree identification book. Pencils and 

sheets of paper to record tree identification information. Or visit http://www.oplin.org/tree/.

Day 4: Pencils and identification sheets prepared from 

Days 2-3. Extra paper.

Day 5: Pencils, paper, and calculators (optional).

Procedures

Day 1

1. Introduce the topic of biological diversity and discuss why diversity is important in natural systems.* 

Explain that the project will involve an inventory of all 

trees on the school grounds (or other area), followed 

by a calculation of the measure of biological diversity 

represented by those trees. 

2. Divide the school ground or other area into two 

sections. Assign two for each section. Tag and number sequentially all of the trees in each section of the 

school grounds or other area. Alternatively, one team 

can inventory the school grounds, and another can inventory an adjacent area. From each tree, take a few 

samples of branches with leaves. (Take enough so that 

students can identify whether the leaves are opposite or alternating, and simple or compound.) Put the 

samples in plastic bags that are numbered sequentially 

to match the tree from which they came.

 Natural Inquirer Lesson Plan
70 The Urban Forest Edition

Day 2: 1. Have each student guess which area 

they think has more tree diversity. Have each 

student record their guess.

2. Identify the trees using the samples and a tree 

identification book (or a Web-based tree identification key).

3. Record each tree’s name (common and biological) on a sheet of paper according to the sequential tag numbering.

Day 3: Using a sample from each tree species, do 

leaf rubbings or have students draw each leaf on 

a sheet of paper, along with the common and biological name and the location of the tree. Other 

characteristics of the tree may be noted on the 

sheet as well. These characteristics should come 

from direct observation of the tree and from the 

tree identification book. For example, is the tree 

native to the area? Does it produce nuts? Each 

student should have a collection of sheets showing all of the trees inventoried in their area.

Day 4: 1. Count the total number of trees growing on the school grounds (or other area). This 

should equal the total number of samples collected. This number will be identified as N. (N=the 

total number of trees of all species.) 

2. Count the number of each individual tree species identified on the school grounds. This number will be identified as n. (n=the total number of 

trees of each species.)

Day 5: 1. Calculate the amount of diversity using 

Simpson’s Index. Simpson’s Index is calculated 

using this equation:

 

D= 3 n (n-1) D=Diversity. In this equation, the

 N (–1) value of D ranges between 0 and 1.

 

Now, to calculate Simpson’s Index of Diversity, subtract the value of D from 1.

Simpson’s Index of Diversity also ranges between 0 and 1. 

1=infinite diversity and 0=no diversity.

For example—

Species Number (n) n (n-1)

Red maple 4 4X3=12

White oak 2 2X1=2

Holly 9 9X8=72

TOTAL (N) 15 86

N (–1) = 15 (14) = 210

D = 86/210

D = .4095 or .41

Simpson’s Index of Diversity = 1-D 1-.41 =.59

2. Now compare Simpson’s Index of Diversity between the two areas. Which area is more diverse? 

How many students had guessed correctly about 

which area is more diverse?

3. Hold a class discussion about biological diversity as 

represented by the diversity of tree species. 

4. Have students put their own leaf rubbings and 

information sheets into a notebook or on a poster. 

Any additional information learned could be added 

to demonstrate the biological diversity (or lack of it) 

of the area that they studied. 

Do not forget to remove the sequential tags from 

the trees when you have finished with the project!

Assessment—

Formal assessment: Create a rubric for the student notebooks or posters. You could require the 

student projects to clearly display the leaf specimen, common and biological names, and location. You could require students to identify what 

they know about that species within the area 

they studied. For example, how many trees from 

that species were found in the area? How much 

additional information did they add? You should 

also require correct spelling and punctuation.

Informal assessment can be done through class 
71

The Natural Inquirer • Volume 6 Number 1

discussions, observations of group interactions, 

and participation.

Modification:

• Students that have difficulty reading or doing 

the other tasks can be paired with a partner or 

the educator may want to assist the student.

• Students that need an extra challenge can go 

to http://www.cnr.vt.edu/dendro/forsite/si4.

htm. At that Web site, they can learn how 

to measure the trunk diameter and height of 

the trees in their area. They can measure the 

trunk diameter and the height of trees in their 

area, and add this information to their poster 

or notebooks.

* What is biological diversity? Scientists use the 

word biological diversity to describe the variety 

of life on Earth. Over the past 550 million years, 

the diversity of life has increased, meaning that 

more different kinds of organisms exist today 

than when the first multicellular animals appeared. 

Species diversity is important. Recent ecological 

research shows that an area of land with many 

plant species is more productive and resistant to 

drought, pests, and other stresses than a comparable area with only a few species.

The diversity of genes, cells, organisms, and ecosystems is a hallmark of life on Earth and one of 

the reasons that life has survived and prospered 

despite periodic catastrophes.

Biological diversity is measured in different 

ways. The two main factors are richness and 

evenness. Richness is the number of different 

species in an area. Evenness is the abundance 

of individuals within a species. In this project, 

students will assess the richness and evenness of 

the tree species growing on the school grounds 

or in another area.
PLEASE COPY THIS FORM BEFORE COMPLETING.

STUDENTS—Tell Us What You Think About The Natural Inquirer

1. The article I read was entitled: _____________________________________________________

Circle the answer that best describes how you feel about the article you just read.

2. The article was: Easy to understand Hard to understand Very hard to understand

3. The article was: Very interesting Somewhat interesting Not interesting

4. Did you learn something from reading the article? Yes No

5. Did you try to answer the Reflection Questions? Yes No Some of them

 If you read and tried to answer any of the reflection questions, did they help you to think 

about the article? Yes No

6. Would you like to read another article? Yes No

7. How old are you? 9 10 11 12 13 Other age: 

8. What grade are you in? 4th 5th 6th 7th 8th 9th 

9. Are you a girl or a boy? Girl Boy

 Now write in your answer: 

10. What did you learn from reading the article? _________________________________________

_______________________________________________________________________________________

_________________________________________________________________________________________

_________________________________________________________________________________________ 

11. What is your favorite subject in school? _____________________________________________ 

Along with your class or by yourself, please send this form to:

Dr. Barbara McDonald • Forest Service • 320 Green St. • Athens, GA 30602-2044

Thank You!

72

The Urban Forest Edition
For each article that you read, please answer the 

following:

Name of Article:_____________________________

 

1. Would this article help you meet any of the required statewide science curriculum standards?

 Yes No

2. How close to the appropriate reading and comprehension level for your students is this article 

written?

 Very close Somewhat close Not close

3. If the article is somewhat close or not close to 

the appropriate reading and comprehension level, 

is it: Too hard Too easy

4. Would or did you use this article in your classroom as an educational resource?

 Yes No 

Why or why not? ______________________________

_____________________________________________

__________________________________________

5. Please rate the article sections on a scale of 1 

to 5. One means the section was not useful at all, 

five means the section was very useful.

 Not useful Very useful

Glossary 1 2 3 4 5

Introduction 1 2 3 4 5

Methods 1 2 3 4 5

Results 1 2 3 4 5

Implications 1 2 3 4 5

Graphs, figures, photos 1 2 3 4 5

Reflection Questions 1 2 3 4 5

FACTivity 1 2 3 4 5

For any of the sections you rated with either a 

“one” or a “two” in question 5, please indicate why 

the section was not useful or how it can be improved:

Glossary_________________________________ 

 

Introduction _____________________________ 

 

Methods ________________________________ 

Results __________________________________

Implications _______________________________ 

Graphs, figures, photos ____________________ 

 

Reflection Questions ______________________ 

FACTivity_________________________________ 

6. Was the “Note to Educators” useful to you?

 Yes No Somewhat

7. What grade(s) do you teach? _____________ 

 

8. What subject(s) do you teach? ____________ 

 

9. Other comments or suggestions: _____________

_____________________________________________

_____________________________________________

_________________________________________

 

 

Please send this evaluation, along with your 

students’ evaluations, to 

Dr. Barbara McDonald

Forest Service

320 Green St.

Athens, GA 30602-2044

Thank you! Your evaluations will help us to 

continually improve The Natural Inquirer.

P L E A S E C O P Y T H I S F O R M B E F O R E C O M P L E T I N G .

The Natural Inquirer

Teacher’s Evaluation

73

The Natural Inquirer • Volume 6 Number 1
What You See is Not 

What You GetI’ve Got You CoveredSocial GroupiesBalancing ActGood To the Last DripYard Sale!Don’t Be So Fuelish!

74

The Urban Forest Edition

 Which National Science Education Standards* 

Can Be Addressed by the Natural Inquirer?

 

Science as Inquiry 

Abilities Necessary To Do Scientific Inquiry ✔ ✔ ✔ ✔ ✔ ✔ ✔

Understandings About Scientific Inquiry ✔ ✔ ✔ ✔ ✔ ✔

Physical Science 

Properties and Changes in Properties in Matter ✔ ✔

Motions and Forces 

Transfer of Energy ✔ ✔

Life Science 

Structure and Function in Living Systems ✔ ✔ 

Reproduction and Heredity 

Regulation and Behavior ✔ ✔ ✔ 

Populations and Ecosystems ✔ ✔ ✔

Diversity and Adaptations of Organisms ✔ 

Earth and Space Science 

Structure of the Earth System ✔ 

Science in Personal and Social Perspectives 

Personal Health ✔ ✔ ✔ ✔ 

Populations, Resources, and Environments ✔ ✔

Natural Hazards 

Risks and Benefits ✔ ✔ ✔ ✔

Science and Technology in Society ✔ ✔ ✔ ✔ ✔ ✔ ✔

History and Nature of Science 

Science as a Human Endeavor ✔ ✔ ✔ ✔ ✔ ✔ ✔

Nature of Science ✔ ✔ ✔ ✔ ✔ ✔ ✔

History of Science 

* National Research Council, Content Standards, Grades 5-8
75

The Natural Inquirer • Volume 6 Number 1

Visit these Web sites for more information:

USDA Forest Service:

http://www.fs.fed.us

The Natural Inquirer:

http://www.naturalinquirer.usda.gov

Conservation Education:

http://na.fs.fed.us/spfo/ce

USDA Kid’s Page:

http://www.usda.gov/news/usdakids/

Agriculture in the Classroom:

http://www.agclassroom.org

Urban Forest Links

http://www.treelink.org

Urban Forestry Resources:

http://www.urbanforestrysouth.usda.gov

Urban Forestry Glossary:

http://www.lpb.org/programs/forest/glossary.html

NatureWatch:

http://www.fs.fed.us/outdoors/naturewatch/

Woodsy Owl:

http://www.fs.fed.us/spf/woodsy

Smokey Bear:

http://www.smokeybear.com

National Forests by Map:

http://www.fs.fed.us/recreation/map/finder.shtml

National Forests by State:

http://www.fs.fed.us/recreation/map/state_list.shtml

What Is the USDA 

Forest Service?

The Forest Service is a part of the United 

States Department of Agriculture (USDA). It is 

made up of thousands of people who care for the 

Nation’s forest land. The USDA Forest Service 

manages over 150 national forests and almost 20 

national grasslands. These are large areas of trees, 

streams, and grasslands. National forests are similar 

in some ways to national parks. Both are public 

lands, meaning that they are owned by the public 

and managed for the public’s use and benefit. Both 

national forests and national parks provide clean 

water, homes for animals that live in the wild, and 

places for people to do fun things in the outdoors. 

National forests also provide resources for people 

to use, such as trees for lumber, minerals, and 

plants used for medicines. Some people in the 

USDA Forest Service are scientists, whose work 

is presented in this journal. USDA Forest Service 

scientists work to solve problems and provide new 

information about natural resources so that we can 

make sure our natural environment is healthy, now 

and into the future.

What Is Agriculture 

in the Classroom?

Agriculture in the Classroom (or Ag in the Classroom) is a grassroots program coordinated by the 

USDA’s Cooperative State Research, Education, 

and Extension Service (CSREES). The goal of Ag 

in the Classroom is to help students and teachers 

gain a greater awareness of the role of agriculture in 

the economy and in society. The program is carried 

out in each State, according to State needs and interests. People involved at the State level represent 

farm organizations, agricultural businesses, education, and government. 

The mission of the CSREES is to advance 

knowledge for agriculture, the environment, human 

health and well-being, and communities. The CSREES provides leadership to identify, develop, and 

manage programs to support university-based and 

other institutional research, education, and extension. 

What Is the Urban and 

Community Forestry 

program?

The Forest Service’s Urban and Community 

Forestry program promotes the management of 

forests and other natural resources in cities and 

communities so that urban forests can be healthy 

now and into the future. The program works with 

people, organizations, and communities to plan for, 

protect, establish, and manage trees, forests, and 

other natural resources in urban areas and local 

communities.
Natural Inquirer editorial review board members.

FS-809

Spring 2005

United States 

Department 

of Agriculture

Forest Service

Northeast Center for Urban and 

Community Forestry:

http://www.umass.edu/urbantree/

Midwest Center for Urban and 

Community Forestry:

http://www.na.fs.fed.us/spfo/urbanforestry/

ucf.htm

Mid-Atlantic Center for Urban and 

Community Forestry:

http://www.fs.fed.us/na/morgantown/

macucf/index.htm

Urban Forestry South Expo:

http://www.urbanforestrysouth.org

Center for Urban Forest Research:

http://cufr.ucdavis.edu/

Urban Forestry South:

http://www.urbanforestrysouth.usda.gov

Visit these Web sites for more urban forest information:

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

its programs and activities on the basis of race, color, national origin, sex, 

religion, age, disability, political beliefs, sexual orientation, and marital or 

family status. (Not all prohibited bases apply to all programs.) Persons with 

disabilities who require alternative means for communication of program 

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

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

To file a complaint of discrimination, write USDA, Director, Office of Civil 

Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, 

SW, Washington, DC 20250-9410 or call 202-720-5964 (voice and TDD). 

USDA is an equal opportunity provider and employer.