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"Sustainable
Forestry" Lesson Plan
Keywords: sustainable
forestry, forest sustainability, forest harvesting, forest regeneration,
interfering plants, overstory structure, high grading, stand age
structure, stand vertical structure
Prepared by: James Finley and Sanford Smith, School of Forest
Resources, Penn State
Grade Level: ninth through twelfth grade and adults
Total Time Required for Lesson: 90 to 120 minutes
Setting: forest stand with small to large sawtimber trees
(12 to 18 inches and larger), some overstory species diversity is
desirable, nearby a stand with recent harvesting
Subjects Covered: biology, ecology, and mathematics
Topics: forest ecology, plant competition, forest stand dynamics
Goals for the Lesson
- Students will understand
how tree harvesting changes forest stand structure
- Students will understand
how light affects forest stand dynamics
- Students will learn
six stand characteristics affected by harvesting
- Students will understand
the need evaluate residual forest conditions
- Students will understand
the need to establish regeneration
Materials Needed
For each plot (four to
six students per plot)
State Standards Addressed:
E & E Standards: Renewable and Nonrenewable Resources (4.2);
and Human and the Environment (4.8)
Teaching Model:
Experiential Learning Model (Experience, Share, Process, Generalize,
Apply)
Preparation
Locate suitable stand
of at least one acre or larger, with an over structure of sawtimber
size trees of a diverse species mix. Ideally, the stand will also
contain trees in the smaller diameter-size classes (e.g., trees
from one inch to ten inches). A stand with an understory component
containing woody and herbaceous plants is also desirable (e.g.,
ferns, grasses, forbs, mountain laurel, striped maple, rhododendron,
spice bush) as well as tree regeneration (e.g., seedlings and saplings
of desirable and undesirable species).
Experience and Share
Phases (45 minutes)
Explain to the students
that the intent of this exercise is to understand that cutting trees
changes things in a forest. Ask them to discuss with you why we
cut trees. Discuss some of the products we use from the forest that
necessitate cutting trees. Some students will likely oppose cutting.
Point out that this is valid, but note that we all use wood and
forest products and that people will have to cut some trees to meet
these needs.
Locate plots such that
they will not overlap when a radius of 37.2 feet is described around
the center. Break the students into equal groups and assign each
group a plot. Students will use a rope, held above the center point
to describe the circle. Each group will then break into three "small"
groups and students will select trees for harvesting based on species
(one small group) and stem diameter (two small groups) using a specific
ribbon color for each treatment. The intent is to show how different
cutting decisions change forest species composition, structure,
and potential to provide products and values.
For example, have one
color ribbon placed on all trees in the plot of one or two species
(e.g., all the red and white oaks, or all the sugar maples) have
a second color used on all trees in the plot above a given diameter
(e.g., 12 inches and larger, a common size used in diameter limit
cutting), and have the third color used on all trees in the plot
below a given diameter (e.g., 10 inches and smaller, representing
a firewood harvest). None of these particular treatments will necessarily
result in a sustainable harvest.
Process Phase (15
Minutes)
After the students have
"carried out" the treatments, have them discuss and describe
what would happen if the forest were harvested by these methods.
Possible questions are:
- Is there a species
removed or severely reduced by one of the treatments?
- What species are left?
- How did the various
"cuts" affect wildlife?
- Will trees capable
of producing seeds remain?
- What has happened
to the average tree diameter remaining?
- How will the "cuts"
change light conditions on the forest floor?
- What will happen to
the plants growing on or near the forest floor?
- Where will the next
forest come from after the harvest?
Students should then
revisit the plots and discuss their observations. By sharing their
observations, they will begin to address the ideas of sustainability.
Sustainability involves taking from the forest those things we need
for today, but retaining the options for future generations to have
the same or improved options. Likely none of the treatments used
by the students will result in a sustainable outcome.
Obviously, removing one
species is not desirable in most cases. Removing just the big trees
will likely swing species composition, reduce the average diameter,
and create irregular use of the upper canopy space. This is a form
of high grading and seldom results in a desirable outcome. Removing
the smaller understory trees will create a park like appearance
that may improve the stand's appearance, but these trees are often
beneficial to wildlife and songbirds. Their removal is also likely
not desirable. What is the proper decision?
The intent of a forest
thinning or improvement harvest is to remove some of the trees of
various sizes in all species, to improve the overall quality of
the forest (i.e., taking trees at risk of dying, with poor or misshapen
crowns, having stem defects, or of undesirable species). Those trees
with large healthy well-shaped crowns are often the ones best retained
in the forest canopy. A forest harvest should result in more options
rather than fewer.
Generalize Phase
(10 minutes)
After discussing with
them the impacts of their cutting decisions on one or more of the
plots, ask them to list things that we could do to make sure that
forest harvesting is sustainable. Generally, from a timber perspective,
the answers will fall into six groups:
- Retain species composition
- Retain tree quality
- Protect residual trees
- Establish regeneration
(preferably natural and not planted)
- Improve growing conditions
for the best trees
- Protect the soil and
site productivity
Optional Activity
(30 minutes)
If time allows, have
the students use a 3.72 foot radius circle somewhere in their plot
to count and identify forest regeneration species. This plot is
1/1,000 of an acre. They try to exercise care not to damage the
regeneration. How many trees are there to the acre? Their count
multiplied by 1,000 provides this answer. A stand in Pennsylvania
is likely to successfully regenerate if there are from 20,000 to
100,000 seedlings per acre. Have the students speculate about why
there are lots or few seedlings on their plot. Is it too much shade,
lack of seed source, deer browsing? What?
Assessment/Apply Phase
(20 minutes)
If possible take students
to a properly marked and harvested forest. You may be able to locate
a good example by contacting a local service or state agency forester.
Refer to Forest
Stewardship Bulletin Number 3: Teaching Youth about Forest Stewardship
(276K pdf) "Appendix: Selected Resources" or look
in the blue pages of your telephone directory under State Government
to locate the office nearest you. Contrast the good example with
a poor one. Again, ask the forester for suggestions on finding a
poorly harvest site. Reflect on the plots the students marked.
Conclusion
In concluding the exercise,
emphasize that forestry is not merely cutting trees. It involves
understanding tree growth requirements, forest history, stand dynamics,
and the potential impacts of poor decisions. Share with the students
Forest
Stewardship Bulletin Number 7 (238K pdf) and Forest
Stewardship Bulletin Number 12 (144K pdf).
References
Smith, Sanford S., James
C. Finley, Shelby E. Chunko, Stephen B. Jones, and Ellen M. O’Donnell
(1999). Forest
Stewardship Bulletin Number 3: Teaching Youth about Forest Stewardship.
University Park, Pa.: The Pennsylvania State University.
Bihun, Yuriy M., James
Finley, Stephen B. Jones, and Ellen Roane (1995). Forest
Stewardship Bulletin Number 7: Timber Harvesting: An Essential Management
Tool. University Park, Pa.: The Pennsylvania State University.
Shelby E. Chunko, and
Wilbur Wolfe (1997). Forest
Stewardship Bulletin Number 12: Best Management Practices for Pennsylvania
Forests.
University Park, Pa.: The Pennsylvania State University.
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