Discovering the Old Growth: Plant I.D. and Biodiversity
Developed by Jennifer Beard and Megan Hanson
Age Level:
6th-8th grade
Group Size:
6-8 students
1 facilitator
Time:
75 minutes
Themes:
Biodiversity
Subjects:
Science
Social Studies
Language Arts
Visual Arts
Concept:
The diversity of
organisms is part of
the natural processes
essential to the
survival of all living
things. Species
diversity, the number
and variety of species
in an area, is one
indicator of ecological
health and changes in
relationship to forest
structure and
complexity.
Location:
HJ Andrews
Experimental Forest
Objectives
By the end of this lesson, students will be able to
1. Use a dichotomous key
2. Identify at least 6 plants within the McKenzie River watershed
3. Describe in detail 1 plant found in the old growth
4. List the characteristics of the old growth using the acronym
OWLS
5. Discuss at least 1 reason why biodiversity is important in the
McKenzie watershed
Overview
Students will explore the composition and structure of the old
growth, observing how biodiversity changes in different areas of the
forest. Students use a dichotomous key as a scientific tool to identify
a plant species, which they will sketch, use their senses to describe,
and give a brief presentation to the group. Their skills in observation
are supplemented by informational cards, outlining the range,
habitat, and cultural uses of the plant they present. The
characteristics of the old growth forest are outlined using the
acronym OWLS: Old, Woody, Layers, and Snags. Students use OWLS
to answer clues on a quest through the old growth, leading to a final
discussion on the theme, biodiversity. Students are asked to critically
think about how we can live in the world in a way to promote natural
biodiversity.
Rationale
Oregonians have the spectacular opportunity to explore old growth
forests. Unfortunately, despite the fact that there are old growth
forests accessible, many families miss the opportunity to show their
children these magnificent sites. Middle school students are at the
age where they are beginning to find their place in the world.
Presenting new and tangible concepts in an experiential learning
space allows students to explore their relationship to the natural
world. Introducing the 4 characteristics which define the old growth
(OWLS: Old trees, Woody debris, Layers, Snags) invites students to
open their ‘owl’ eyes and engage their senses on a quest to discover
each of the components of OWLS.
Biodiversity is a leading theme in the long term research at HJ Andrews. Understanding biodiversity
is an important aspect in recognizing ecological health. Engaging students in experiential learning as
scientists builds upon H.J. Andrews Long Term Ecological Research Themes while stimulating
attitudes of empathy, excitement, and concern for the environment and current environmental
issues. Exposure to Kalapuya and Molalla plant names and uses links the lesson to people and place.
Materials
Plant I.D. and Biodiversity
 9 dichotomous keys (attached at end of lesson)
 8 sheets of paper (Rite-n-Rain paper for wet days)
 8 pencils
 Plant cards (attached at end of lesson)
 flagging
The Quest
 4 laminated clues (attached at end of lesson)
 4 discussion questions
 Wicker basket (3 more wicker baskets optional)
Getting Ready
Plant I.D. and Biodiversity
Familiarize yourself with the dichotomous key and the species it identifies. With flagging, mark the
plants students will key out.
The Quest
Hide all clues, except for clue 1 (woody debris) along the trail. Wicker baskets provide protection in
the rain.
 Clue 2: Old trees is hidden in woody debris/nurse log
 Clue 3: Snags is hidden next to a snag
 Clue 4: Layers is hidden next to old trees
Place discussion questions in the basket and hang it in the tree. They are the answer to the layers
clue.
Background
The McKenzie River Watershed has been inhabited for over 8,000 years. The Kalapuya and Molalla
are 2 tribes that prospered in the McKenzie River watershed, yet today relatively few native people
remain in the area. The ecological environment supports their lifestyle of building shelter out of
mud, hemlock and cedar, making baskets, and gathering medicines and food - huckleberry, valerian,
fern and Oregon grape. (Jones, 2014 and Williams, 2014).
A dichotomous key is a tool used for species identification. It is method of categorization that
works by starting at the broadest category (such as deciduous or coniferous) and eventually
narrowing down to a specific genus or species. The species can fit only 1 of the 2 character
descriptions such as: 1a. A tree or shrub, 1b. Not a tree or shrub. Dichotomous keys are ubiquitous
to the field of biology and are used to identify plants, animals, and fungi.
The old growth forest provides a unique habitat for a diverse community of plants and animals, and
less than 10% of the United States forests are considered old growth. An easy way to remember the
main characteristics of a Pacific Northwest old growth forest is the acronym OWLS.
Old trees refers to the amount of trees over a century old, which can be determined by measuring
tree girth or taking a core sample. Old trees, along with new trees, provide diversity among tree
ages and sizes, creating unique habitats for many plants and animals. For example, moss living on
old tree branches are associated with cyanobacteria. Cyanobacteria are crucial to forest health
because they turn atmospheric nitrogen into a form usable to plants and animals. Moss and
cyanobacteria are abundant in the high canopies of old, living trees.
Woody debris refers to the fallen trees found on the forest floor. Once a tree falls, it provides
essential nutrients to the soil and homes for new trees and plants. A nurse log is a fallen tree that
seedlings grow upon. For example, western hemlock seedlings, a shade-loving tree, are often found
growing on top of nurse logs. Eventually microorganisms and fungi will break the fallen trees down,
recycling the nutrients back into the soil for new trees and shrubs to grow upon.
Layers symbolize the canopy layers, from the step moss that carpets the forest floor to tall Douglasfir. The height difference among different plant species provides unique habitats for numerous
species. For example, osprey prefer the highest tree closest to the body of water they are
inhabiting, (in our case, the McKenzie River), while a woodpecker prefers the lower part of a tree.
The osprey prefer the tops of trees closest to the river, because they are fishing birds, and this
provides them an advantage in getting the resources they need to stay alive. On the other hand,
woodpeckers snack on decomposers in the lower part of the tree and tree sap. Layers also allow
different amounts of light to seep through the canopy, providing a variety of habitat and increasing
the biodiversity of the forest.
Snags are standing dead trees that provide a distinct habitat for several types of animals and
provide more life than a living tree. Snags are home to many decomposers, and will eventually turn
into soil. They are also home to spotted owls, which are an indicator species for the Pacific
Northwest.
Old growth forests face many natural threats, including fire and floods. These threats may seem
destructive, but they are essential and part of the natural cycle of a forest. When forests burn or
flood, the canopy floor is left with mineral soil. In the old growth surrounding the McKenzie River,
mineral soil is essential for the reproduction of Douglas-fir trees, along with many other species.
Douglas-fir trees can grow fast and provide shade for many other species that require shade to
grow, such as the western hemlock. With time, Douglas-fir trees will begin to fall, and in the light,
the western hemlock trees begin to grow faster. The fallen trees become nurse logs and the varying
layers provide habitat for many different species of plants, animals, fungi, and bacteria. After about
800 years, a forest may become a climax forest when, in this example, the Douglas-fir upper canopy
is replaced with a western hemlock upper canopy. This evolution of steps within a forest is called
succession. Succession comes in cycles, and is the long term process leading to the formation of an
old growth forest.
HJ Andrews Experimental Forest is used for long term research in biodiversity, succession and
canopy structure. Biodiversity refers to the variety of life in a particular habitat, ecosystem, or the
entire world. Species diversity takes into account both species evenness and richness. Species
evenness quantifies the relative abundance of species in a defined area, whereas species richness is
the total number of different species represented in the area.
HJ Andrews is a biodiverse ecosystem and defined as a temperate coniferous old growth rainforest.
This unique ecosystem is home to “thousands of species of insects, 83 bird species, 19 gymnosperm
species, and 9 species of fish” (HJ Andrews, 2008). An ecosystem is a biological community of
interacting organisms in their environment; i.e. everything that exists in a particular environment.
Temperate is an area with a mild climate. Conifer is a type of tree that produces seed bearing cones
and in most cases, is evergreen. Evergreen denotes a plant that retains its leaves or needles
throughout the year, unlike a deciduous plant that loses its leaves in the winter. Old growth refers
to the climax stage, or last “stable” stage of a forest.
Activity Instructions
Part A. Plant I.D. and Biodiversity (30 minutes)
1. Frame the lesson (1 minute)
a. Explain to the students that this station covers the composition and structure of the
temperate coniferous old growth rain forest. Through using a dichotomous key and
going on a quest, we will discover the hidden treasures of the forest and unveil the
magnificent biodiversity of the old growth.
2. Name your favorite plant species and state why (2 minutes)
a. Evaluate the level of knowledge of species. Ask each person in the group to name
and describe their favorite plant species.
i. Give assistance by defining species: a group of organisms similarly related
and capable of interbreeding and producing viable offspring.
3. Dichotomous Key and Plant I.D. (27 minutes)
a. Introduce the concept of a dichotomous key.
i. Q: Has anybody heard of a dichotomous key?
1. A: Break the word apart: di means 2; dichotomy means to split into 2
parts, and a key is a tool to enter a place or allow a means of access.
In this case, a key is to find the name of a species. (hold up key)
ii. Explain to the students that a dichotomous key is a reference tool, which,
through a series of choices, leads to the identification of a species. Each
choice is represented by a couplet; 2 descriptions which are mutually
exclusive lead to the next couplet, a and b, until a conclusion (species name)
is reached. If you are not sure about the description, you can look ahead, or
turn around and go back.
b. Hand out the keys. As a team, use the key to identify 1 species (i.e. Douglas-fir,
Pseudotsuga menziesii). Make sure everyone follows along with each step.
c. Give instructions for the keying activity: “Each student will be given a plant to
identify. If you have a question or when you think you have correctly identified the
plant, raise your hand. When you have correctly identified the plant, you will be
handed a plant card, which gives more information about your plant’s
characteristics and how it is used both today and in historical times. Then, take
some time with the plant to get to know it. Write a description in as much detail as
imaginable using your senses. How does it feel? How does it smell? Do NOT try
tasting it today; we do not know if it is safe or toxic. What does it look like up close?
Sketch its unique features in detail, like a naturalist. There is a list of questions on
the back of the key to help guide your descriptions and sketches as well as
identifying terms and pictures to assist in keying.”
d. Explain that each student will be share what they learn about their species with the
group, so be sure to observe closely, compile information, and sketch your very
best.
e. Assign each student a different species from the key that also has a plant
card. (Douglas-fir, western hemlock, western red-cedar, vine maple, pacific yew,
salal, sword fern, Oregon grape, stair step moss)
f. When a student identifies the correct species, hand them the associated plant card.
Give students about 10 minutes to sketch and describe the plant.
g. Gather students together to present species. Find a space where everyone can hear
each other easily. Collect dichotomous keys and plant cards. Ask students to point
out the plant to the group, share their sketch and highlight key features.
Part B. OWLS in the Old Growth (15 minutes)
1. Introduce the concept of OWLS (11 minutes)
a. “Has anyone heard of the acronym OWLS to represent the characteristics of the old
growth?” Go through each letter and elaborate via inquiry.
b. “O stands for Old Trees! Everyone point to an old tree.”
i. Ask: How old are the oldest trees in this forest? How old is old?
ii. Extra info: Old trees refers to the amount of trees over a century old, which
can be discovered in the mere girth of a tree. Commonly Douglas-fir reach
200 ft tall and live 500-1000 years. It takes a Douglas-fir 200 years before
developing old growth characteristics. Old trees, along with new trees,
provide a diversity among tree ages and sizes, which hosts a plethora of
unique symbiotic relationships. The biggest trees in the forest weigh more
than the largest animal on earth, the Blue Whale, are ⅔ the height of the
Statue of Liberty and sprouted at the time Christopher Columbus arrived to
the “Americas.”
c. “W stands for Woody Debris. Everyone point to some woody debris.”
i. Ask: What functions or services does woody debris supply the forest
ecosystem? Nurse logs host an abundance of species. Can you point out a
“nurse” log?
ii. Extra info: Woody debris references the fallen trees and nurse logs that are
found on the forest floor. Once trees fall, their remains provide essential
nutrients to the soil and provide homes for new trees and plants, eventually
microorganisms will break them down into mineral soil for new trees and
shrubs to grow upon.
d. “L stands for Layers. Point to the canopy. Point to the understory. Point to the
forest floor.”
i. Ask: What function does having multiple layers serve?
ii. Extra info: Layers include everything from the forest floor to the upper
canopy everything in between. Large branches and the height difference of
various trees create a multilayered canopy with a variety of habitats for
different species. For example, Osprey prefer the highest tree closest to the
body of water they are inhabiting (in our case, the McKenzie River), while a
woodpecker prefers the lower part of a tree. Furthermore, with layers,
different amounts of light seep through in separate areas throughout the
forest, which provides opportunity for more variation, thus higher
biodiversity. The microclimate differs between the treetop and forest floor.
e. “S stands for Snags. Point out a snag.”
i. Ask: Why might snags be important? How did a snag come to be a snag?
ii. Extra Info: Snags are similar to nurse logs, however they are still standing
and provide a distinct habitat for several types of animals (i.e. termites,
beetles, woodpeckers, squirrels, etc). They are a storehouse of nutrients for
the forest ecosystem. Lightning, fire, disease (i.e. heart rot fungus) and
insect pests (i.e. bark beetles) can form snags.
2. Review OWLS. through a kinesthetic experience (4 minutes)
a. Go through each letter, asking the students to show with their body what each
letter stands for. Tell students to get their owl eyes ready because they are going on
a quest.
Part C: The Quest (30 minutes)
1. Introduce the Quest (1 minute)
a. Tell the students that there are 4 clues representing each letter in OWLS (Old,
Woody, Layers, & Snag)
2. Quest (19 minutes)
a. Give the students the clue 1. Have a student read the clue to the group.
i. Answer: nurse log or woody debris
ii. Have the students:
1. Find the nurse log (where clue 2 is hidden).
2. Ask the students to identify 6 species growing on the log. If they do
not know the name, use descriptions.
3. Ask what services the nurse log is providing (i.e. habitat, food for
decomposers).
b. Have a different student read clue 2.
i. Answer: old trees
ii. Have the students:
1. Find the largest Douglas-fir (where clue 3 is hidden).
2. When they are at the tree, have students stand around it for 30
seconds in silence, listening and using their senses.
3. Ask the students to share their observations (if time permits).
c. Have another student read clue 3.
i. Answer: snag
ii. Have the students
1. Find the snag where clue 4 is hidden
2. Explain 1 function of a snag
3. List 3 plants or animals that use snags for habitat.
d. Have another student read clue 4.
i. Answer: layers
ii. Have the students:
1. Look up and down and all around. Then proceed over the log bridge.
2. List layers of the forest
3. List 2 functions of the canopy
3. Biodiversity discussion (8 minutes)
a. There are 4 discussion questions. Have students pair up and choose a question out
of the basket. If there are only 6 students, pair question 3 and 4 together. Give
students a few minutes to discuss and think about answers.
b. Explain that after discussing in pairs, each pair will read their question and share
their response. Open up the discussion to the entire group, if time permits.
c. Go around to each group and help them think through the questions with these
prompts
i. Question 1: Think about how biodiversity is measured and the different
components of biodiversity. Think about OWLS.
1. Possible answers include:
a. Measured at genetic, species, and ecosystem levels.
b. Components: species composition, species richness, and
species abundance
ii. Question 2: Think about natural process, food and medicines, and quality of
life.
1. Possible answers include
a. Natural processes: A diversity of organisms take part in
natural processes important for the survival of life (i.e. food
webs).
b. Food and medicines: Mushrooms and rhizomes are food.
Conk mushrooms and yew contain cancer-fighting agents.
c. Quality of life: Human’s quality of life and necessary
resources are affected by different species and ecosystems.
iii. Question 3: Think about how humans impact the forest
1. Possible answers include:
a. Invasive species, deforestation, logging, agriculture and
grazing, climate change
iv. Question 4: Think about how humans can protect the forest.
1. Possible answers include:
a. Research, education, protected areas (parks and reserves),
restoration
4. Assessment (2 minutes)
a. Using a circular whip, ask students to name 1 species and describe at least 1
characteristic of that species OR
b. Using a circular whip, ask students to use OWLS to name one of the characteristics
of an old growth forest or describe that characteristic.
Clues for the Quest
Clue 1
The next step is a small test,
Answer to move farther on the quest,
Guess what part of the old growth forest I am?
I once was mighty and tall
Now I am diminished and small
I give my nutrients to the ground
For all the creatures that make little sound
Lots of things grow out of me
Often times, another tree
My habitat is one all on its own
Amphibians, fungi and plants call me home.
Now that you’ve figured me out, look for me, and find the next clue.
Clue 2
Now that you’ve found my sister down on the ground,
Imagine what the Native Americans might have found.
I am tall and strong, and one of the oldest around.
You can tell how old I am based on my girth,
But I promise you that isn’t all that I’m worth.
I am a home to many species, some since birth,
And I provide branches where many-a birds can perch.
Look for me and notice my rough, furrowed bark,
Touch it and smell it, but please don’t leave a mark.
On your next journey, you must embark.
Clue 3
I might not look like much to you - after I died maybe from a windstorm, lightning strike, or a landslide
but I play my part in the forest ecosystem as a service and a structure,
I am habitat to spiders, ants, beetles, birds and fungus mixtures
I contain cavities, home to nesting animals such as the spotted owl
so although I may be old and rotten, all the better for future decomposition
when I fall I will be a blessing upon creatures tall and small
What part of the old growth am I?
Clue 4
One story, two story, upper story, under story
Cycling seasons within my own vicinity,
Trees and leaves shade hemlock productivity
Openings horizontally allow new members to join the community
Closure vertically keeps things cool while the sun hits coniferous crowns
And together we create a complex system that science studies successionally all around
What part of the old growth am I?
To find your final clue: Walk up and over the log, find a partner, and prepare for some
concluding dialogue.
Discussion Questions
1. What is biodiversity? How does
biodiversity vary in the old
growth and how does the old
growth encourage biodiversity?
2. Why is biodiversity in the forest
important?
3. What are threats to forest
biodiversity?
4. What are some conservation
measures that can be taken to
ensure the protection and
continuation of forests?
Citations
Clue one of the Quest is from 2012 Canopy Connections. Canopy Connections, Environmental
Leadership Program, University of Oregon.
Bonady, Devon. Northwest Ethnobotany Field Guide. University of Oregon. 2011.
Canopy Connections 2011. Home is Where the Forest Is. Environmental Leadership Program,
University of Oregon.
Halpern, C.B., and J.A. Lutz. Canopy closure exerts weak controls on understory dynamics: A 30-year
study of overstory-understory interactions. Ecological Monographs 83:221-237. 2013.
HJ Andrews Experimental Forest.Overview of Andrews Forest biodiversity research, Long Term
Ecological Research. March 2008.
http://andrewsforest.oregonstate.edu/lter/research/component/biodv/summary.cfm?sum=biorch08&topnav=58
Johnson, Oscar. The Molalla People of Clackamas County. Smoke Signals Spring 1999. Date Accessed
2 June 2014. http://www.usgennet.org/usa/or/county/clackamas/molallas.html
Jones, Eric, T. A Great Diversity to Harvest. The Portland Ethnobotany Project. 2104. Date Accessed:
2 June 2014. http://www.globalgiving.org/projects/portland-ethnobotany-project/updates/
Li, Judith L. Ellie’s Log, Exploring the Forest Where the Great Tree Fell. OSU Press, Corvallis. 2013.
Pyers, Greg. Biodiversity of Temperate Forests. Marshall Cavendish Benchmark, New York. 2012.
Schertow, John, Ahni. Connection to a Place. IC Magazine. 29 Dec. 2010. Date Accessed 2 June 2014.
http://intercontinentalcry.org/connection-to-a-place/
Williams, Gerald, W. The Oregon Encyclopedia:McKenzie River. PSU 2008-2014. Date Accessed 2
June 2014. http://www.oregonencyclopedia.org/entry/view/mckenzie_river/