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Cast of Thousands
2
Overview
Students will further explore the variety of life in their
adopted forest and will discover the importance of this
biological diversity. They will take measurements, in much
the same way as a forester does, to draw conclusions about
the overall health of their forest. As an extension, students
will compare the information they have collected with that
of another class in a different region.
Background
No one knows for certain how
many different kinds of plants
and animals live on this planet.
So far, scientists have classified
only about 1.5 million different
species, but they estimate there
may be from 40 million to 80
million in the world. A species
is a group of organisms that
resemble one another in appearance, behavior, chemical
makeup, and genetic structure.
Organisms must be able to
breed with one another and
produce fertile offspring if they
are to be considered the same
species.
One of Earth’s most valuable
resources is its biological diversity, or biodiversity.
Biodiversity is a term that
encompasses the diversity of life
on the planet, reflected in the
variety of habitats and species,
and in the genetic variation
within species. In the
Encyclopedia of the Environment
by Eblen and Eblen, biodiversity
is connected to natural resources
as follows: “Originally mostly
food, fiber, and materials for
shelter, biodiversity has come to
encompass a wide and growing
set of resources such as paper,
pulp and its derivatives, pharmaceuticals, latexes, resins, and
essential oils. Entire government
departments and agencies are
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AMERICAN FOREST FOUNDATION
oriented around various aspects
of the biological resource base:
agriculture, health, fisheries,
forests, etc.”
Foresters help to manage
forest resources to provide for
timber, wildlife, clean air,
water, and other forest
resources. Forestry is more
than just planting trees and
fighting forest fires, although
those tasks may be part of a
professional forester’s responsibilities.
Urban foresters specialize in
caring for the nearly 70 million
acres of forests that grow in
and around metropolitan communities. They pay close attention to the factors that affect
those forests, such as limited
growing space, poor air, lack of
water, poor soil quality, and
vandalism. (More information
on factors that affect plant
growth is in Activity 3, “The
Nature of Plants.”) Urban
foresters try to increase the
average life span and maintain
the aesthetic quality of trees in
city parks and forests.
Although foresters are trained
in managing all forest
resources, foresters often call on
other professionals who specialize in individual parts of the
forest, such as soils, water, or
wildlife. Usually, foresters and
specialists work together as a
team to decide how to care for
the forest so that it provides all
Subjects
Biology, Environmental
Science, Language Arts,
Geography, Math, Social
Studies
Concepts
k Forests, as well as other
ecosystems, contain numerous habitats that support
diverse populations of
organisms. (1.2)
k The Earth’s atmosphere,
water, soil, climate, and
geology vary from region
to region, thus creating a
wide diversity of biological
communities. (1.3)
k In biological systems,
energy flows and materials
continually cycle in predictable and measurable
patterns. (7.1)
As
organisms go through
k
their life cycle of growth,
maturity, decline, and
death, their role in the
ecosystem also changes.
(13.3)
Skills
Analyzing Data, Comparing
and Contrasting, Observing,
Organizing Information,
Researching, Using Teamwork,
Writing Reports
Objectives
Students will (1) make scientific measurements of their
forest, (2) examine the relationships of organisms to their
environment, and (3) determine the extent to which
humans have an impact on
forests in their region.
Materials
Copies or overheads of the
five Student Pages: “Forest
Measurement Guide” on
pages 38-40, “Tree Damage
and Signs of Disturbance” on
page 41, “Inventory
Recording Form” on pages 4245, “Soil Studies” on pages 4648, and “Abiotic
Measurement Chart” on page
49 for the Enrichment Activity
(optional). See the Getting
Ready section for more
details.
Time Considerations
Preparation: 30 minutes
Activity: Four 50-minute
periods or one field trip
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the things people need and
want from it. In this activity,
your students will work
together in groups like a team
of specialists to further investigate their adopted forest.
Getting Ready
Copy these Student Pages:
“Forest Measurement Guide,”
“Tree Damage and Signs of
Disturbance,” “Inventory
Recording Form,” and “Soil
Studies.” Optional: copy the
Student Page “Abiotic Measurement Chart” for the enrichment
activity. Gather the items listed
below for the measurements
you want your students to
take. If you plan on doing the
extension activity where students compare the data they
have collected with another
class, you may want to complete and return the “Forest
Exchange Box” form before you
begin this activity (see page 36).
Plot measurement materials:
a 50- or 100-foot (15- or 30 m)
measuring tape (teams can share,
also used to measure tree diameter),
small strips of flagging, ribbon or
yarn (bright colors preferred), a
map of the forest area (can be
homemade), twine or rope.
Tree height measurement
materials: plastic drinking straw,
tape, protractor, string, and a coin.
Microfauna measurement
materials: white cardboard pieces
1-foot square or white sheet, agar,
petri dishes, and hand lenses.
Slope measuring materials: 25inch (62.5 cm) board, small jar, and
water or a level.
Soil collection and pH measurement materials: trowel, paper
cups or small plastic bags, pH paper,
buffer solutions, distilled water,
petri dishes, eye dropper, and tablespoon. Note: pH paper, agar and
petri dishes can be purchased
from laboratory supply companies. (See the Bibliography for
listings.)
Sunlight measurement materials:
cardboard tubes from paper towel
rolls (cut in half) or bathroom tissue
cores.
Wind measurement materials:
four 5-foot (1.5-m) poles or sticks,
four 3-foot (.9 m) lengths of 1-inch
(2.5 cm) wide strips of crepe paper
or silk-like material, four nails,
compass.
Useful materials: reference materials for identifying trees, shrubs,
wildflowers, birds, and so on. (See
recommended list in the
Bibliography under Field Guides, or
contact your state or city forester
for publications on local flora and
fauna.)
Doing the Activity
1 Explain to students that they
are going to be given an
opportunity to study the
major components of their
adopted forest.
2 Ask students what compo-
nents of a forest ecosystem
they think are important to
measure and list those items
on paper for later reference.
3 Be sure the list includes
recording measurements and
observations of trees,
shrubs, herbaceous plants,
28 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
wildlife, and the site’s physical characteristics and soils.
In addition to these features,
students will attempt to
measure the less obvious
components of the forest,
such as the insects, other
invertebrates, and microorganisms that make up the
“cast of thousands.” If you
plan to do the Forest
Exchange Box Extension
Activity, you may want to
share this with your students to motivate them to
collect the data.
4 Break the group into teams
of four to eight students.
Explain to students that
after they have roped off sections of the forest into plots,
they will take different measurements of those areas.
(See the section on
Measuring the Forest for
more information.) These
measurements include:
k tree species by number
k diameter of trees at breast
height (dbh = approximately 4.5 feet, or 1.4 m,
above ground)
k height of trees and crown
spread (estimate height
using techniques described
on the “Forest Measurement
Guide” Student Page)
k tree regeneration, or the
relative abundance by species
k tree damage and signs of
disturbance (determine
possible causes such as fire,
insects, hurricane, or disease; number and proportion
of live trees affected; and
number of dead trees or
snags)
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k shrubs and density, or the
k
k
k
k
k
number of shrub species in
the understory, their abundance, and their height
herbaceous layer and
ground cover, or the
grasses, wildflowers,
mosses, and ferns (number
of species present and abundance of each)
macrofauna, or the wildlife
observations of mammals,
amphibians, reptiles, and
birds
microfauna, or the observations of insects and other
invertebrates
topography and other
influential physical characteristics of the land, such as
slope, presence of glacial
erratics (rocks and boulders
deposited by retreating glaciers), or a hardpan layer (an
impermeable layer of very
dense soil and rock below
the softer surface soil), and
proximity to water
soils including litter or
organic layer.
Measuring the Forest
The following directions will
guide your students through
the measurements and observations of their forest. Before you
take your students in the field,
review the terms and measurement techniques highlighted in
the steps below. Student teams
will gather data for their measured plots (or measured pieces)
of the forest. A professional
forester familiar with the forest
you are studying would be an
excellent resource at the site. He
or she may be interested in
receiving a report of your students’ findings.
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1 Plot measurement
Explain to students that
plots may be circular or
square, depending on terrain
and obstacles. If you have a
large tract of land, additional
adult supervision will be
required to ensure students’
safety. On the basis of available time, you may choose
to let each student team have
its own plot and take all the
measurements or pick just a
few items to measure.
Another alternative is to
have one big plot and have
different student teams take
different measurements.
Ideally, the adopted forest
plot should be identified on a
larger forest map to establish
location and boundaries. In
the field, each team should
decide whether to use a circular or square plot and should
proceed to mark the boundaries of its plot.
a. For a circular plot, have
each team define a circle in
the forest with a radius of
37.2 feet (11.2 m), which
represents a 1/10 acre plot
(4,356 square feet, or 392
square meters). A stick with
a bright flag can be used to
denote the center of the plot
(make sure teams don’t
overlap). Using a 50-foot
(15 m) measuring tape, each
team will measure 37.2 feet
(.2 foot is about 2.5 inches
or 6.3 cm) from the plot
center, and will circle the
center with the tape outstretched, flagging the
perimeter.
b. For a square 1/10-acre
plot, have teams define a
square with sides 66 feet
(20m) long. Two strings
stretched diagonally from
corner to corner can be used
to establish the plot center,
boundaries, and corners. The
boundaries of the plot can be
flagged.
Circular Plot
37.2' RADIUS
Square Plot
66'
2 Tree species
Have students familiarize
themselves with the different
tree species in their area.
Review these species as needed
using reference books and try
to collect twig or leaf samples of
trees. In the forest, students
should use the “Inventory
Recording Form” to record the
number of trees of each species
in their plot. (See the
Bibliography in Appendix 1 for
examples of tree field guides.)
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TEACHER NOTE
You will need to make enough
copies of the “Inventory Recording
Form” Student Page so students can
list the different species they find. In
place of making copies, you could
show students the template and
have them record this information in
a notebook or journal.
3 Tree size
In the field, have students
record tree diameter at breast
height (dbh), height, and crown
spread of trees. Have them use
the Student Pages “Forest
Measurement Guide” and
“Inventory Recording Form.”
Measure the
circumference
5 Tree damage and signs of
disturbance
In the forest, tell students to
look for any unhealthy,
dead, or damaged trees. They
should refer to the Student
Page, “Tree Damage and
Signs of Disturbance,” which
lists descriptions of various
tree health problems and
symptoms. Ask students to
consider what could have
caused dead or dying trees.
They should be able to determine the proportion of trees
affected by disease or insects,
how many were damaged
by other factors, and how
many have died. Have them
look for evidence of leaf
destruction, twig and stem
deformities, fungal growths,
or other injuries on the tree.
Introduce students to basic
insect and disease pests of
your area. A city or state
forester could help with this
topic. Have students record
their observations.
4.5 feet
6 Shrubs and density
4 Regeneration
In the forest, have students
record any seedlings present
on the forest floor, the various species (if this can be
determined), the relative
density (dozens per plot or
just a few scattered
seedlings), and general
health of these plants (color,
damage, and so forth). Have
them record their findings
on the “Inventory Recording
Form.” Be sure students dig
carefully and gently in the
leaf litter when searching for
signs of very tiny seedlings.
Shrubs are woody plants
(witch hazel, blackberry, and
raspberry, for example) that
occupy the forest understory
and generally range in
height from 2 to 12 feet
(.6 to 3.6 m). Given good
growing conditions, shrubs
grow more dense over time,
spreading out rather than
growing up. Often, tree
seedlings, sprouts, and
saplings occupy the same
space as shrubs and compete
with shrubs for light and
moisture. In the forest, have
students examine the shrubs
in the understory of their
plot and record their observations on the “Inventory
Recording Form.” Have stu-
30 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
dents determine if the shrub
layer is dense or sparse. Ask
students to predict how the
shrub density might affect
wildlife populations. Have
students measure and record
the height of low-lying
shrubs. Have students try to
determine the relative health
of the shrubs. Use the
Student Page “Tree Damage
and Signs of Disturbance” as
a reference. Use field guides
to determine species. (See the
Bibliography for listing.)
7 Herbaceous layer and
ground cover
Have students identify and
list the herbaceous plants,
including wildflowers,
grasses, mosses, and ferns
that are present on the site.
Have them look for fungi
that may be growing in
moist areas. Then have them
estimate the percentage of
the plot covered. Students
should record this information in the Herbaceous
Layer/Ground Cover
Inventory section of the
“Inventory Recording Form.”
Ground cover plants often
serve as indicator species and
help foresters determine the
relative fertility of the site.
(See the Bibliography in
Appendix 1 for Field Guides.)
8 Macrofauna: animals easy
to spot
Have students record their
observations of mammals,
birds, reptiles, and amphibians or signs of these animals, such as tracks, deer
rubbings, droppings, paths,
browse, dens, nests, and so
forth, on the “Inventory
Recording Form.” This exercise requires a relative degree
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of stealthiness and patience
since a group of students
entering a forest will tend to
frighten away any animals.
Try creating a bird blind to
watch birds, or go to the forest early in the morning
when animals may be feeding. Although finding signs
of wildlife is useful, encouraging your students to maintain a quiet and respectful
approach to their adopted forest will be rewarded with
more actual animal sightings.
9 Microfauna: animals and
organisms easy to miss
Have students look for
types, numbers, and evidence of insects, other invertebrates, and microorganisms. They should pay
particular attention to the
forest floor, using hand
lenses to help in the search. If
there are open areas, students should compare them
with areas covered with litterfall or grass, then record
data on the “Inventory
Recording Form.” Using the
Student Page “Soil Studies,”
students should study soil
samples for signs of
microorganisms.
10 Topography
On the “Inventory Recording
Form,” have students mark
“F” for flat, “S” for sloping,
and “H” for hilly. Although
this analysis can be approximated at the local level, a
topographic map from the
U.S. Geological Survey (for
more information see the
Bibliography) will give your
students an accurate and
graphic picture of the topography around their chosen
©
AMERICAN FOREST FOUNDATION
site and will help them better
understand the effects of
regional topography on a
small area. What may
appear to be flat or slightly
rolling land could be a very
broad watershed delta that
distributes the flow of water
and silt from distant mountains or hills. Glacial remnants (lakes, cuts, valleys,
and so forth) are evident on
quadrangle maps. Students
will measure the slope of
each of their plots to give an
average slope of the forest.
(See “Forest Measurement
Guide” for procedure.)
When students are studying
the topography, encourage
them to identify water
resources that may affect
their adopted forest. Rivers,
even though distant, may
rise to fill a flood plain or
basin that encompasses the
adopted forest. Streams,
creeks, ponds, moistureretaining soils, near-surface
water sources, and known
underground streams all
contribute moisture to a
forest. A hydrographic map
of the region (if available)
may help students identify
sub-surface aquifers that
affect their forest. Also, you
should try to consult a local
forester or hydrologist.
the Student Page “Soil
Studies.”) The site’s physical
characteristics may often be
tied to the regional topographic characteristics, as
noted above. Students should
be aware of soil features like
glacial till (a blend of clay,
sand, gravel, and boulders)
and glacial erratics (large
stones or boulders moved
great distances and then
deposited by glaciers).
Have students note plant
material and microorganisms within the samples.
Microorganism and pH measurements can be done with
the soil samples in the classroom. (See Student Page “Soil
Studies” for explanations
and data compilation.)
Have students search their
plots for evidence of human
activity. For example, they
may find discarded pieces of
glass, paper, charcoal, or
building/brick fragments.
They can use hand lenses to
more carefully examine the
soil for its components.
Soil Profile
Horizon A
Organic Layer, humus
Horizon B
Fine particles, clay,
and minerals
Horizon C
Course fragmented
soil materials and
minerals
11 Soils
To enable students to determine the soil type have them
take soil samples down to 1
foot (30 cm) deep to examine
and measure the depth of
organic litter and humus.
Students will determine soil
moisture using these samples. (Both are explained on
Parent Rock
or Bedrock
Horizons differ in size depending on
soil composition, climate, and so forth
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Discussion and
Follow-up
1 Ask students to share data
with each other to determine
tree types (deciduous, coniferous, young, old, mixed,
and so forth) and dominant
species of their forest. Ask
students for ways they can
share their data (for example, list findings on a
flipchart, posterboard, computer printout, or overhead
transparency) and choose
the most appropriate
method. Begin having the
teams report on the types
and numbers of trees in their
respective plots, starting
with the most commonly
found tree. The list should be
made in descending order of
total numbers reported.
Have students multiply the
number of trees per plot by
10 to arrive at an estimate of
the total trees per acre. This
figure will roughly indicate
the forest type.
Encourage students to
develop a large-scale working map (for example, 4 foot
x 4 foot, or 1.2 m x 1.2 m)
of their area of the adopted
forest. The map could be
used as a reference for plot
information. Each team can
draw the findings on its plot
and record, with symbols,
pins, colors, and so on. An
effective map should include
topographic, soil condition,
and hydrographic (freeflowing and ground water)
information.
2 Come to a consensus on the
topography and physical
characteristics of the forest.
Consider whether the site is
rolling, flat, hilly, or mountainous and whether the soil
was dry, mesic, or hydric.
Record this decision on the
board (or on the table-top
map if one is used). This
information can be checked
on a topographic map from
the U.S. Geological Survey
(address is in the Bibliography
under the map section).
3 Survey students about the
kinds and prevalence of tree
damage, insects, diseases,
and tree mortality they
observed. Write these observations on the board. What
conclusions do the students
draw from their observations? Do they think the forest is healthy? Why? Do
they think there is a major
problem caused by insects,
disease, people, or other factors? Have students explain
and encourage them to
develop cause-and-effect
relationships.
4 Come to a consensus on
shrub density and height.
(Individual recordings on
each plot may vary.) Is the
forest generally hard to
walk through (high shrub
density)? Is it lacking a
shrub understory? Why?
What is the significance of
the understory (or lack of
one) to each plot? To what
factors do the students
attribute the nature of the
understory? For example,
does the forest have a history of a fire that may have
cleared the understory?
32 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
5 Ask students what types of
herbaceous plants and
ground cover they observed?
Does the forest support a
diversity of ground cover?
6 Ask students if they
observed any tree regeneration (seedlings or sprouts).
If so, were they able to identify the different species?
Write observations on the
board or identify them on
the table-top map. Is there a
trend in the species of trees
regenerating? Do students
think the new growth is
shade-tolerant or shadeintolerant. Can some species
that begin as shade-tolerant
seedlings become shadeintolerant as they mature?
(See Activity 1, Student Page
“A Look at Competition.”)
7 Ask students what kinds of
wildlife they observed
directly or discerned
through indirect observation. Have students develop
a chart by animal category
and size (mammals - large
to small; birds - raptors to
seed eaters; reptiles and
amphibians; invertebrates).
Encourage students to correlate their observations
with the physical aspects of
the forest and draw conclusions about expectations for
animal life in other types of
forests.
8 Ask students what type of
soil was found in the forest
at different depths? Is there a
class consensus? What is the
pH at different depths? Do
the students think that the
soil of the area helps to determine the plants and animals
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at the site? Were there any
signs or remnants of human
activity in the soil? Have students hypothesize about
how they got there.
9 Ask if there was evidence of
decomposition of dead
organic matter. Was there
evidence of insects, other
invertebrates, or microorganisms involved in the
decomposition process? Ask
students to estimate populations of microorganisms
(numbers, kinds, diversity)
per volume or weight of
soil. (See the “Soil Studies”
Student Page for procedure.)
10 Review the list of important
forest measurements that
the students originally generated, and make necessary
modifications to it.
11 Ask students to write a
paragraph about how their
adopted forest might change
during a 6- to 12-month
period.
Enrichment
Have students measure additional abiotic (nonliving) components of their forested plot.
Students will focus on sunlight,
temperature, and wind.
regarding each abiotic variable. A more concise average
will be determined if more
groups study each variable.
k Sunlight. The amount and
intensity (brightness) of
sunlight falling on a forest,
from the canopy through to
the ground, plays a critical
role in the forest environment. Every living and nonliving element of a forest
ecosystem is affected by the
presence, or absence, of sunlight. Ask students to determine how much sunlight
penetrates the canopy and
falls on the ground at each
study site. Students may
determine light intensity at
each site by using a photographic light meter or photosensitive paper. If those
items are not available, they
can use descriptive terms,
such as shady, dark,
medium light, or bright.
The students can estimate
the canopy cover by using a
cardboard tube (a bathroom
tissue core or a paper towel
tube cut in half) as a simple
densimeter (a device for
measuring density). By
looking up at the canopy
through the tube, they can
roughly estimate the canopy
cover. If the view through
the tube is completely
obscured by leaves or
branches, the canopy is full
or 100 percent covered. If the
student can see half sky and
half leaves through the tube,
the canopy could be
described as 50 percent covered, and so on. Averaging
several tube readings per site
will provide the best estimate of canopy cover.
k Wind. Because forests serve
as natural windbreaks, the
effect of wind on an ecosystem varies from upwind to
downwind. Have the team
prepare at least four wind
strips—5-foot (1.5m) poles
or sticks with lightweight
streamers (3-foot (.9m)
lengths of 1-inch-wide (2.5
cm) strips of crepe paper or
silk-like material) fastened
Wind Strip Diagram
3'
5'
1 To begin, ask students to contrast the abiotic and biotic
components of their forested
plot. Then have them make a
list of abiotic variables that
they can study.
2 Divide students into teams
so that two teams can be
assigned to investigate and
record their observations
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AMERICAN FOREST FOUNDATION
200'-300'
Downwind
200'-300'
Wind Direction
Upwind
Wind Experiment Diagram
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at the top of the pole with a
nail so that the strip can
move freely around the pole
(see diagram). Have students
set one pole 200-300 feet
(60-90 m) upwind from the
forest or study site, and one
pole at the upwind edge of
the site. The other two poles
should be set up downwind
of the site: one at the edge,
and the other as far from
the downwind edge as the
farthest upwind pole is set
(see diagram).
Once the poles are in place,
have students note the wind
direction (using a compass)
and relative strength of the
wind at each pole at the same
time. If the strips are hanging limp, the students
should note “no wind.” If the
strips are flapping gently,
note “light wind.” If the
strips are consistently held
away from the pole, but not
perpendicular to it, note
“moderate wind.” If the
strips are being blown perpendicular to the pole for
more than a minute, note
“strong wind.” Measure the
wind at each site for at least
10 minutes, and repeat over
the course of several visits, if
possible. When students
have collected their wind
data, have them compare
their observations with the
physical features that characterize the upwind area and
the downwind area of the
forest or site. They should be
aware of humidity, soil
moistness, seed and seedling
distribution, animal nests or
burrows, flying insects, and
so forth, all of which are
affected directly by the
strength and direction of the
wind. It is worthwhile to
note that gaps in a forest and
local topography can actually accelerate wind at or
just above ground level.
k Temperature. Ask this team
to measure each site’s air
temperature at 6 inches
(15 cm), at 1 foot (.3 m),
and at 3 feet (.9 m) above
ground. Have them measure
soil temperature at 3 inches
(7.5 cm), 6 inches (15 cm),
and 1 foot (30 cm) below
the ground. To measure soil
temperature, place the thermometer into the soil at
each depth for approximately 2 minutes; then
record the temperature.
3 After teams have had suffi-
cient time to conduct investigations, have them all come
together to share what they
have learned. You may select
one central location outside
or return to the classroom.
4 Ask teams to record their
data on the Student Page,
“Abiotic Measurement
Chart.” Use the data as a
basis for discussing the differences among the locations
and any interactions students observed among the
elements. Some sample
questions follow:
site had the highest
? Which
air temperature? The lowest?
The most wind? The least?
What differences do these factors make in comparison to
other sites?
Do plants seem to affect the
? light
intensity, air tempera-
34 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
ture, and soil temperature in an
area?
How does water seem to
? influence
the soil tempera-
ture, air temperature, and soil
moisture?
is the relationship
? What
between sunlight and air
temperature? Between sunlight
and soil moisture? Between
sunlight and soil temperature?
Between sunlight and plants?
On the basis of their wind
? measurements,
ask students
why they think windbreaks are
important.
of the three elements
? Which
we studied seems most
important for determining the
character of the environment at
each site? What is the basis for
that conclusion?
5 If possible, visit each site
again at a different time of
year and repeat the investigations. Compare the
results: How has the character of the soil changed? The
temperature? The wind? The
plants and animals? What
factors influenced each of
these changes?
6 Another option is to “bring
nature indoors.” Once students have observed various
parts of the forested ecosystem in the field, work with
them to replicate portions of
those systems in one or
more classroom terrariums.
Terrariums can provide students with the opportunity
to isolate particular aspects
of a forest ecosystem (a rotten log, for example).
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Students can manipulate the
biotic and abiotic conditions
to better understand the
relationships among a forest’s light, chemical, energy,
and water dependencies, and
its animal life cycles. (See
“Bringing Nature Indoors” in
Appendix 4 for complete
directions on setting up terrariums that represent different ecosystems.)
Extension: Forest
Exchange Box
Use Project Learning Tree’s
Environmental Exchange Box
Program to exchange information and develop comparative
views about forests with students in another region of the
United States or in another
country.
Before doing this activity,
you’ll need to find a group with
which to exchange forest
boxes—and PLT can help! Just
photocopy the following form,
fill it out and send it to us. We’ll
find a match for you and send
you the address of another educator who is doing this activity.
Please allow approximately
four weeks for us to find a
match for you.
1 Once you have the information on your exchange
group, tell the students that
they are going to exchange
“forests” with a group of students. Explain that the students to whom your group
will be sending their box may
have limited knowledge
about your location. It will
be the group’s responsibility
to generate data, facts, and
reports for the box that will
©
AMERICAN FOREST FOUNDATION
teach the students who
receive the box all about
forests in your region.
2 On the basis of your forest
investigations thus far,
brainstorm with the students to prepare a list of
materials to include in the
box. Have the students divide
up the responsibilities for
collecting and preparing
materials for the box.
Students might want to consider including some of the
charts, data, descriptions,
pictures, or actual forest
artifacts from the investigation of your adopted forest.
The following are examples
of information to include:
k
k
k
k
k
k
k
k
k
k
k
tree species
tree sizes
topography
soil type and moisture
list of insects and microorganisms
shrub density
ground cover
regeneration
list of wildlife
list of people’s use and
dependence on the forest
local environmental issues.
SAFETY NOTE:
Many states have laws regulating
the types of plant and animal materials that can cross their borders. Be
sure to check with the state department of agriculture or a local office
of the agricultural extension service
to find out about restrictions in your
exchange state before you send any
plant or animal materials.
3 While waiting for the box
from your exchange group
to arrive, have students
research the other group’s
region. Have them develop a
team-based report on the
region, detailing factors such
as longitude, latitude, climate
and seasonal information,
topography, and demographic-political information
(cities, capital, border neighbors, and so forth). On the
basis of their research, have
students develop what they
believe to be a likely forest
scenario for the exchange
region. What kind of trees
should they expect to see and
why? What are the seasons
like? What kind of soil, landforms, and animal life are apt
to be common to the region?
What, if any, impact might
humans be having on the
region’s environment? Have
there been any news stories
about the region related to the
environment or the forest
ecosystem?
4 When the box arrives from
your exchange group, open
it with the students and
examine the contents. If
your site study teams are
still in place, distribute the
contents of the box according
to team specialties, and have
the teams prepare a comparative analysis report of their
materials. The following are
some questions you might
have them consider:
Do the materials match their
? expectations?
Why or
why not?
What are the significant dif? ferences
between the
regions? Do the climates and
forest types compare? If the climates compare, but the forests
don’t, why not?
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FOREST EXCHANGE BOX
Name:
____________________________________________________________________________________
School:
____________________________________________________________________________________
School Address:
____________________________________________________________________________________
Telephone Number at Work: (
)_____________________ Home: (
) ____________________
Grade Level/Age of Students:
____________________________________________________________________________________
Preferred U.S. state, territory, or region with which you would like to exchange:
____________________________________________________________________________________
Copy, complete and return this form by mail or fax to:
Project Learning Tree, American Forest Foundation
1111 19th Street, NW., Suite 780, Washington, DC 20036
FAX 202-463-2461
the other students sent soil
? Ifsamples,
how do they compare
Do migratory habits of ani? mals
in your region play a
5 As a wrap-up, have the students create a representative
picture or description of their
“exchange forest” using
what was in the exchange
box. What do they imagine
it would be like to live in that
region? What actions could
be taken to conserve the natural resources represented by
items in the box?
?
Forest Exchange Box
Follow-up
with the soils in your region?
kinds of animals and
? What
plants live in both places,
and what animals and plants
are mutually exclusive?
role in the forests of the
exchange students’ region?
Are there differences in the
way people live and depend
on the exchange region’s
forests?
After completing the exchange,
help your students assess how
well it went. How helpful was the
information or artifacts included
36 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
in the exchange box that they
received? How well did it represent the ecological or cultural
environment of your partner’s
region? As a class, have students
formulate a list of questions they
have about items in the box or
general questions about the
forests in that geographic region.
Perhaps they would like more
information or clarification on
items that were sent in the box.
They should send their questions
to the partner teacher and wait
for a reply.
The local media may be interested in your exchange project.
You (or the students) may want
to inform your local newspaper,
radio station, or television station
about the results of the project.
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Page 37
Assessment Opportunity
1 Have students apply the knowledge they
gained in the activity to answer these
questions:
might we do to keep further damage
?haveWhat
from occurring? Which human actions might
a positive effect on the ecosystems? What
might we do to encourage more of these kinds of
actions? Did students see evidence of logging or
tree planting?
Was there a serious problem that seemed to
Were most tree seedlings of the same species as
? affect
? the
the health of this forest? If yes, what
trees found in the canopy? If not, why?
What might this forest look like in 5 years? In 50
years? In 100 years? Will it be different from what
it looks like today? If so, how will these changes
affect the way the forest is used?
is your adopted forest used by people? Is
? itHow
used for hiking, skiing, or other forms of
recreation? Which human actions have harmful
effects on these ecosystems? Which might be beneficial? Are these effects short term or long term?
©
AMERICAN FOREST FOUNDATION
are some things students could do to address
the problem.
2 Using the forest measurements, have students
graph various factors including, but not limited to, the following:
k height and diameter of the trees within the
plot
k height and density of shrubs species
k sightings or evidence of animals on the forest
floor, understory, and canopy
k various soil elements found in the different
soil samples.
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Student Page
Forest Measurement Guide
MEASURING TREE DIAMETER
Once you have identified the various tree species in your adopted area, measure a good sample
of each type (for example, five trees per species). Use a tape measure to measure the circumference of the tree at a standard height from the ground. Foresters use the measurement dbh—
diameter at breast height, which is about 4.5 feet (1.4m) above ground—as standard. With the
circumference data in hand, the conversion to diameter is simple:
π
circumference in inches divided by 3.14 ( )=diameter in inches
MEASURING TREE HEIGHT
Measuring height is somewhat difficult in a dense forest. But you can estimate tree heights where you can
Straw
see the tree’s crown by using a clinometer. You may
want to ask a forester to show your students how to
Protractor
use a professional clinometer. Or you can make your
180°
own clinometer by using a protractor, a straw, some
String
90°
Coin
string, and a small weight. (See diagram).
To use the instrument, (a) find a tree on fairly level
and stand far enough away from it to see the
ground
Attach the straw to the protractor with tape.
top of the tree looking through the straw, (b) have a
Attach the string to the straw. Place a weight on
the end of the string using tape.
partner steady the weight and string against the protractor and read the number where the string crosses
the protractor, (c) obtain “A,” the angle of elevation, by subtracting 90 from the number read on
the protractor, and (d) have your partner measure in feet the horizontal distance “ab” from where
you are to the base of the tree.
c
Tape
0°
Note: the protractor should be held
with the 180° mark next to the person’s eye.
X
A°
Notes:
a
b
1 These directions assume that you are lying down on flat ground (eye level with the base of
the tree) and looking through the straw. If you are standing, you will have to add your
height to the final calculation to get a more accurate estimation of the tree’s height.
2 The tangent of 45° is 1. Hence, if you are measuring a tree that happens to have a 45° angle
of elevation, the height of the tree will be equal to the distance between a and b.
3 As the height of the tree increases, so does the angle of elevation. (The greater the angle of
elevation, the greater the tangent.)
4 Before you try this in the field, you may want to practice by measuring heights of buildings
or other tall objects near your school.
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38 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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Student Page
Forest Measurement Guide
By using the formula ab x Tangent A = X, we can determine the height of the tree, where:
ab = the distance from the tree
A = the angle of elevation
X = the height of the tree
Tangents are determined by using tangent charts (See the chart below.)
Example 1:
if ab = 35 feet, and A = 34°, then the tangent of A = 0.6745
35 x 0.6745 = X
23.61 = X (the height is approximately 24 feet, or 7.3 m)
Example 2:
if ab = 35 feet and A = 60°, then the tangent of A = 1.7321
35 x 1.7321 = X
60.6235 = X (the height is approximately 61 feet, or 18.6 m)
TANGENT CHART (A = angle)
A
Tangent
A
Tangent
A
Tangent
A
Tangent
1°
2°
3°
4°
5°
6°
7°
8°
9°
10°
11°
12°
13°
14°
15°
16°
17°
18°
19°
20°
21°
22°
23°
0.0175
0.0349
0.0524
0.699
0.0875
0.1051
0.1228
0.1405
0.1584
0.1763
0.1944
0.2126
0.2309
0.2493
0.2679
0.2867
0.3057
0.3249
0.3443
0.3640
0.3839
0.4040
0.4245
24°
25°
26°
27°
28°
29°
30°
31°
32°
33°
34°
35°
36°
37°
38°
39°
40°
41°
42°
43°
44°
45°
46°
0.4452
0.4663
0.4877
0.5095
0.5317
0.5543
0.5774
0.6009
0.6249
0.6494
0.6745
0.7002
0.7265
0.7536
0.7813
0.8098
0.8391
0.8093
0.9004
0.9325
0.9657
1.0000
1.0335
47°
48°
49°
50°
51°
52°
53°
54°
55°
56°
57°
58°
59°
60°
61°
62°
63°
64°
65°
66°
67°
68°
69°
1.0724
1.1106
1.1204
1.1918
1.2349
1.2799
1.3270
1.3764
1.4281
1.4826
1.5399
1.6003
1.6643
1.7321
1.8040
1.8807
1.9626
2.0503
2.1445
2.2460
2.3559
2.4751
2.6051
70°
71°
72°
73°
74°
75°
76°
77°
78°
79°
80°
81°
82°
83°
84°
85°
86°
87°
88°
89°
90°
2.7475
2.9042
2.0777
2.2709
3.4874
3.7321
4.0108
4.3315
4.7046
5.1446
5.6713
6.3138
7.1154
8.1443
9.5144
11.4301
14.3007
19.0811
28.6363
57.2900
undefined
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Student Page
Forest Measurement Guide
MEASURING THE CROWN SPREAD
To measure the tree’s crown or the crown spread (how far
the branches spread away from the trunk), use an average.
Find the branch that sticks out the farthest and have team
member A stand under it. On the other side of the tree, find
the branch that sticks out the farthest and have student B
stand under it. Have students step in front of the trunk so
the measurement across can be taken. Have a team member
measure the distance between the two students. This is
crown spread at the widest point.
Next, find the two branches on each side that end nearest
to the tree and repeat the same procedure as before.
Determine the average of these two distances to find the
crown measurement.
Farthest Branch
B
A
MEASURE THE DISTANCE
Nearest Branch
DETERMINING SLOPE
To measure slope, use a board 25 inches (62.5 cm) long.
Place one end against the slope to be measured, holding it
level. Next, place a small jar with water in it (about half full)
on the other end of the board, lowering and raising until it is
level (if you have a level you can use it in place of the jar).
B
A
Measure the distance from
the ground to the end of the
board with the jar on it. This
distance (in inches) is then
MEASURE THE DISTANCE
multiplied by the conversion
factor of 4, which gives you the slope of the area in percent.
Repeat this procedure in each forested plot. This calculation
gives the average of the slope within the forest.
Measure the distance between the
ground and the board
MEASURING MICROFAUNA
Gather white pieces of cardboard 1 foot (30 cm) square (the number of pieces will depend on
how many teams there are). Place the cardboard under a shrub and gently shake and rub the
branches so that organisms can fall below to the cardboard. Identify different species, and
replace organisms on the forest floor. Repeat the procedure for low-lying branches on trees and
for small plants. For measuring microorganisms in the soil, see the Student Page “Soil Studies.”
40 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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Student Page
Tree Damage and Signs of Disturbance
Signs or symptoms:
©
Damage cause by:
1
Ragged leaves with holes
Insects feeding on the leaves
2
Black or brown leaves
Stem or leaf disease
3
Spots or bumps on leaves
Insects and mites
4
Twisted or malformed leaves
Insects and disease, herbicides
5
Leaves change color before fall
Trunk or root damage, drought, pollution
6
Branch decay
Unhealed wounds
7
Peeling or broken bark, holes in the bark
Trunk wound, canker disease, or damage
caused by humans or animals
8
Dying branches on one side of crown
Root decay, root injury or internal stem
disease, insect attack
9
Canker (a dead section of a
trunk or branch)
Fungal infections
10 Splits
Broken branches
12 Hollows
Water entering through old wounds
and supporting wood decay by fungi
13 Fungi/mushrooms
Internal decomposition of wood by fungi
14 Green/brown spots on pine needles
Air pollution
AMERICAN FOREST FOUNDATION
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Student Page
Inventory Recording Form
Forest Name:
Date:
Name:
Location:
Type of Plot:
(circular or square)
Tree Inventory
Species #1 (most abundant species)
Tree Species:
Number in plot:
Regeneration:
(No. of seedlings)
Tree Diameter (dbh):
Height:
Crown Spread:
Signs of Disease and Disturbance:
Percent Trees Affected:
Percent Mortality:
Species #2 (second most abundant species)
Tree Species:
Number in plot:
Regeneration:
(No. of seedlings)
Tree Diameter (dbh):
Height:
Crown Spread:
Signs of Disease and Disturbance:
Percent Trees Affected:
Percent Mortality:
Species #3 (third most abundant species)
Tree Species:
Number in plot:
Regeneration:
(No. of seedlings)
Tree Diameter (dbh):
Height:
Crown Spread:
Signs of Disease and Disturbance:
Percent Trees Affected:
Percent Mortality:
Other Tree Species:
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42 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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Student Page
Inventory Recording Form
Name:
Location:
Type of Plot:
(circular or square)
Forest Name:
Date:
Shrub Inventory
Species #1 (most abundant species)
Shrub Species:
Number in plot:
Relative Density of Particular Species:
Height:
Signs of Disease and Disturbance:
Percent Shrubs Affected:
Percent Mortality:
Species #2 (second most abundant species)
Shrub Species:
Number in plot:
Relative Density of Particular Species:
Height:
Signs of Disease and Disturbance:
Percent Shrubs Affected:
Percent Mortality:
Species #3 (third most abundant species)
Shrub Species:
Number in plot:
Relative Density of Particular Species:
Height:
Signs of Disease and Disturbance:
Percent Shrubs Affected:
Percent Mortality:
Other Shrub Species Found in the Plot and Their Relative Abundance:
Overall Density of Understory: (dense or sparse, easy to walk
through or difficult?)
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©
AMERICAN FOREST FOUNDATION
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Student Page
Inventory Recording Form
Name:
Location:
Type of Plot:
Forest Name:
Date:
(circular or square)
Herbaceous Layer/Ground Cover Inventory
Wildflowers
Species or Description:
Percent Cover:
Grasses
Species or Description:
Percent Cover:
Mosses
Species or Description:
Percent Cover:
Other (fungi, etc.)
Species or Description:
Percent Cover:
Overall Percentage of Herbaceous Layer or Ground Cover:
(totally bare forest floor, partially covered, thick, etc.)
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44 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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AMERICAN FOREST FOUNDATION
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Student Page
Inventory Recording Form
Name:
Location:
Type of Plot:
(circular or square)
Forest Name:
Date:
Macrofauna Inventory
Animals Sighted:
Animal Evidence:
Tracks
Burrows
Nests
Dens
Droppings
Microfauna Inventory
Number of Species:
Species or Description:
Location of Sample:
Topographic Inventory
Slope:
(mark ‘F’ for flat,
‘S’ for sloping,
‘H’ for hilly;
also include the slope percent)
Proximity of Plot to Water:
Floodplain?
Watershed or Basin?
Underground Aquifer?
Evidence of Glaciation:
(yes or no; if yes, describe)
©
AMERICAN FOREST FOUNDATION
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Student Page
Soil Studies
Collecting Samples
Measure 1 square foot (0.9 square meters) of ground within the forested plot. (Corners can
be marked with sticks.) Try to choose a site that closely represents the overall forested plot.
For example, if your forest plot is mostly wet and covered with ferns, don’t choose a spot
that is dry and has no ground cover. Within the plot remove and examine the leaf litter layer
(identifiable dead matter on the surface of the floor) and the humus layer (decomposed,
unidentifiable organic matter below the litter). Then collect soil samples at depths of about 3
inches (7.5 cm), 6 inches (15 cm), and 1 foot (30 cm) (use paper cups or small plastic bags
to store samples).
Record results for the following information on the “Soil Elements Recording Chart.”
SOIL MOISTURE
Determine moisture level at each of the three depths. By feeling the soil, you can tell
whether the soil is xeric (dry, low soil fertility), mesic (good moisture and soil fertility), or
hydric (saturated soils, high water table). The depth of organic matter is an important factor influencing soil moisture. Measure how far the organic matter extends into the soil.
SOIL TYPE
Characterize each soil depth as loam, sand, or clay. Use the “Soil Analysis Chart” as a reference. Examine the soil for other characteristics such as color, smell, and the presence of
glacial till and erratics.
Soil Analysis Chart
Soil Type
Soil Squeezed Dry
Soil Squeezed Moist
Sand
falls apart when pressure is
released
forms a cast (molds when formed) but
crumbles when touched
Sandy Loam
forms a cast that will readily
fall apart
forms a cast that will bear careful handling without breaking
Loam
forms a cast that will bear
careful handling
forms a cast that can be handled quite
freely without breaking
Silt Loam
forms a cast that can be handled freely without breaking
forms a good cast that will not “ribbon”
but will give a broken appearance
Clay Loam
breaks into hard clods or
lumps
will form thin “ribbon” that will break
readily, barely sustaining its own weight
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46 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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Student Page
Soil Studies
MICROORGANISMS
Detect microorganisms in the soil by mixing a teaspoon of soil in 500 ml of water, then
putting 0.5 ml (about 12 drops) of this diluted mixture on agar in a petri dish. Place the
petri dishes in a dark place to incubate at room temperature. After one week, record the
number and type of colonies that form on the agar. Compare microorganisms in samples
taken at 3 inches (7.5 cm), 6 inches (15 cm), and 1 foot (30 cm).
pH
1 Measure 1 tablespoon of soil from each depth and place into individual petri dishes, or any
similar glass or plastic containers. Be sure to label each dish appropriately. Wet each soil
sample with 5 drops of distilled water (from an eyedropper). Allow to sit for 3 to 5 minutes.
2 Place one piece of pH paper on each soil sample. (Use pH paper with a range from at least 5-10.)
3 Determine the approximate pH or acid/base level of your soil.
Soil Elements Recording Chart
Soil
Elements
Sample 1
3 inches (7.5 cm)
Sample 2
6 inches (15 cm)
Sample 3
1 foot (30 cm)
Soil Type:
(loam, sand,
or clay)
Moisture Level:
(xeric, mesic,
or hydric)
Number of types of
microorganisms:
pH:
Overall Characteristics:
color, smell,
glacial till/erratics,
abundance of leaf litter,
humus, evidence of
human activity, plant
material, etc.
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Student Page
Soil Studies
Draw a soil profile showing the different types of soil at each depth. Include the overall
characteristics of the soil.
3 inches (7.5 cm)
6 inches (15 cm)
1 foot (30 cm)
48 PROJECT LEARNING TREE The Changing Forest: Forest Ecology
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Student Page
Abiotic Measurement Chart
Sunlight
Intensity
% Cover
Reading 1.
Reading 2.
Reading 3.
Average:
Wind
Downwind
Edge of Plot
Direction
Upwind
200-300 feet
(60-90 m)
Edge of Plot
200-300 feet
(60-90 m)
Strength
Physical Features
Temperature
Below the Ground
Above the Ground
©
6 inches
(15 cm)
3 inches
(7.5 cm)
1 foot
(30 cm)
6 inches
(15 cm)
3 feet
(90 cm)
1 foot
(30 cm)
AMERICAN FOREST FOUNDATION
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