SUCCESSION TO OLD GROWTH IN PENNSYLVANIA
9
OVERVIEW
Students learn about forest succession, the characteristics of old-growth
forests and about some of the old-growth forests that remain in Pennsylvania.
In groups, students design a travel brochure about a specific old-growth forest
in Pennsylvania.
BACKGROUND
Change Over Time: Processes
that Affect the Forest
Succession
Like all ecosystems, forest ecosystems are
ever-changing. After a natural or human
induced disturbance the developmental
sequence or stages of re-growth that a
forest follows is known as succession.
During succession, the forest adapts to
the environment and simultaneously
adapts the environment to itself. As the
plant community changes the animal
community changes with it in response
to changing habitat conditions.
Succession is often referred to as either primary or secondary succession.
Primary succession occurs immediately
after a catastrophic disturbance that
leaves a site without any plant or animal
life and sometimes without soil. An example of primary succession in parts of
northern Pennsylvania would be what
occurred after the receding of the glaciers about 10,000 years ago.
However, if the disturbance is less
severe, only disrupting rather than destroying the biotic community, then secondary succession follows. Examples of
such disturbances include fires, windstorms, landslides, floods, disease, insects,
invasive plants, the effects of grazers and
browsers, and timber harvesting.
Pioneer species that are shade-intolerant generally predominate in early successional stages after a disturbance in a
forest. Since they germinate, grow quickly, and are the first to inhabit the area,
they are called pioneer species. Examples
include aspen, grasses and forbs.
Pioneer species are replaced after a
time by shade-tolerant, longer-lived
plants. The seedlings of these shadetolerant trees become established beneath the forest canopy and eventually
penetrate the canopy and become overstory trees. Some examples of these
species in Pennsylvania’s forests include
sugar maple, American beech and eastern hemlock.
Section II — Activity 9
After a disturbance, and if it is not
disturbed again, the forest stand will
proceed through five general structural
growth phases: seedling, sapling, pole,
mature or sawtimber, and finally old
growth. There are a limited number of
old growth forests remaining in
Pennsylvania — about 15,000 acres —
scattered in about fifty locations
throughout the state. Those that do exist
are mainly hemlock and white pine.
Most of these remnants are found within
Pennsylvania’s state park system, the
Allegheny National Forest, or are held by
private conservancies.
PROCEDURES
1. Hand out copies of the Student Page
“Successional Stages” and discuss the
process of ecological succession with
students. If possible, take students
outside to an area that illustrates several stages of succession.
2. Explain that during succession the
forest adapts to the environment
while simultaneously adapting the
environment itself. Through the
process of succession a forest will proceed through five general structural
or growth phases: seedling, sapling,
pole, mature or sawtimber, and finally old growth. There are certain plant
and animal species that are more likely to be found at each successional
stage.
3. Ask students how they would define
“old-growth forest.” Ask whether
they know of any locations in the
United States where old-growth is located. Have students use the old
growth poster for locations and information. Are they aware of any oldgrowth forest in Pennsylvania? Have
they ever been in an old-growth
forest?
4. Share with students that the definition of old growth is complex and
varies from region to region within
the United States. In general though,
GRADE LEVELS:
Grades 5–10
OBJECTIVES: Students will (1) review the process of forest succession,
(2) discuss the characteristics of an oldgrowth forest, (3) research a specific
old-growth forest in Pennsylvania, and
(4) design a travel brochure about that
forest.
PENNSYLVANIA PROPOSED
ENVIRONMENT & ECOLOGY
STANDARDS ADDRESSED:
4.2.7
C. Explain natural resource distribution.
4.6.7
A. Explain the flows of energy and matter from organism to organism within
an ecosystem.
B. Explain the concepts of cycles.
C. Explain how ecosystems change over
time.
4.2.10
C. Analyze how man-made systems
have impacted the management and
distribution of natural resources.
4.6.10
A. Explain the biotic and abiotic components of an ecosystem and their interaction.
B. Explain how cycles affect the balance
in an ecosystem.
C. Analyze how ecosystems change over
time.
ESTIMATED DURATION: Two to
three 50-minute class periods.
MATERIALS NEEDED: Books, etc.
for research on old-growth; paper; writing and art materials needed to create a
travel brochure.
Succession to Old Growth in Pennsylvania 89
5.
6.
7.
8.
old-growth forests contain the oldest
and largest individuals of certain tree
species. In Pennsylvania they are usually eastern hemlock and occasionally
white pine. These trees can be
300–500 years old or more. Oldgrowth forests also tend to have trees
of varying heights, creating a multilayered canopy. Because of the age of
the forest, dead trees are an important component of an old-growth forest, both those fallen and those still
standing as snags. Old-growth forests
provide a unique habitat that certain
species of plants and animals rely on
for survival.
Briefly discuss the controversy revolving around whether or not to log oldgrowth forests in the Pacific
Northwest. Explain to students that
in Pennsylvania, while we don’t have
much remaining old-growth forest,
most of what we do have is protected
as part of our State Park system, state
forest, national forest system, or by
private conservancies.
Divide students into four groups.
Explain that each group will research
a different old-growth forest in
Pennsylvania and then design a travel brochure about that forest. The
purpose of the travel brochure will be
to inform people about this particular
old-growth forest, to encourage people to visit the forest, and to inform
of its unique value.
Some of the needed information can
be obtained from travel guides and
other books about Pennsylvania. In
addition, you could write to the
agency that manages the forest.
Students should also include some
visuals in the brochure; if actual
photographs of the forest are not obtainable, perhaps a series of drawings
(real or abstract) can be produced. A
map and directions of how to get to
the forest would also be important to
include.
Assign each group one of the following old-growth areas to research. Give
students time to research their forest
and develop their brochure.
Glens Natural Area, Rickets Glen
State Park
Luzerne County
Large track of old growth forest of
eastern hemlock, white pine and
mixed oak; many of the virgin hemlocks are more than 500 years old.
90 Succession to Old Growth in Pennsylvania
Forest Cathedral Natural Area,
Cook Forest State Park
Clarion & Forest Counties
Old-growth stand of white pine and
eastern hemlock; many trees are over
300 years old.
Forrest H. Dutlinger Natural Area,
Susquehannock State Forest
Clinton County
Old-growth stand of virgin eastern
hemlocks.
Heart’s Content Scenic Area,
Allegheny National Forest
Warren, McKean, Elk & Forest
Counties
121-acre tract of virgin white pines,
eastern hemlocks and American
beech.
9. When the brochure is completed,
have each group share with the class
their travel brochure and what they
learned about their old-growth forest.
Display the brochures in the classroom.
EXTENSION
■ Have students design a poster to accompany their brochure. (Or divide
the students into eight groups rather
than four; have two of the eight
groups research the same old-growth
forest, but one group designs the
brochure and the other group designs
the poster for that forest.)
■ Create a bulletin board display about
old-growth forests or have the students create one. The brochures
and/or posters developed by the
groups can be included as part of the
bulletin board.
■ Have students research some of the
plant and animal species that depend
on mature and old-growth forests in
Pennsylvania. Some examples would
include the northern flying squirrel
(Glaucomys sabrinus), northern
goshawk (Accipiter gentilis), and pileated woodpecker (Dryocopus pileatus).
■ If possible, take students on a field
trip to an old-growth forest in
Pennsylvania.
■ Have students research the details of
the old-growth controversy in the
Pacific Northwest.
ASSESSMENT
Have students share their brochures in
presentation form to other classes and/or
to their family members.
Section II — Activity 9