Instructional Kit
Terrestrial Ecology
Teacher’s Instructions for Field Study Activity
Overview of Activity
In this terrestrial field study activity, transect lines will be employed to compare limiting
factors within woodlands, grassy fields, or their associated ecotones. Students should be
divided into three groups of 6 to 8 students. Each group will then be sub-divided into two
teams: a Biotic Team and an Abiotic Team. The Abiotic Team will analyze soil
composition, light, moisture, temperature, and humidity along the transect. Vegetation
and animal life found along the transect line will be observed and classified by the Biotic
Team. When the data are compiled, the students will have a better understanding of the
relationships among limiting factors, living creatures, and what constitutes healthy
ecosystems.
Prior to Activity
Visit the field site prior to the class trip, familiarizing yourself with the area, its safety
hazards, and selecting specific areas for the three transect sites. Students should be
familiar with your rules for lab safety and appropriate behavior.
Establish three different areas for anchoring the 30-meter transect lines with tent pegs
(you will need an assistant to help anchor each line in the areas chosen). The lines should
be located in areas of contrasting vegetation if possible (i.e., woodland, field, shrub, or
ecotones). Assign numbers I, II, III to the transect lines.
Distribute task cards and equipment to the three teams. Teams will have two 30-minute
periods to conduct their tests on two different transects. Direct each team to their initially
assigned transect line. After 30 minutes, direct the teams to rotate to a new transect
(Team I to Transect II, Team II to Transect III, Team III to Transect I). The Biotic teams
and Abiotic teams should switch assignments for their second transect study so that
students will have an opportunity to perform both types of analysis.
Final fifteen minutes: Allow five to ten minutes for equipment collection. Teachers may
want to do some preliminary group data sharing and interpretation at this time.
Student Reports
Once students have returned to the classroom and compiled their data, each team of
students should present a mini-report on their findings. For each report, students should
briefly address and explain the following:
1. How they conducted their tests
2. How they used their equipment
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3. Show their results – including drawings, samples collected, etc.
4. Share their environmental rating and assessment of the health of the site. Students
can use the following scale for their ratings:
Environmental Rating Scale
Excellent (4)
 Area is rich in animal and plant diversity and provides numerous excellent and
Good
(3)
wide range of habitats
 Area has a good number of plants and animals and a good variety of habitats
Fair
(2)
 Area has some plant and animal diversity, some habitats
Poor
(1)
 Area has very little plant and animal diversity, poor habitats, and may be an
unstable or threatened area due to various influences
Closure Questions
After student reports, the teacher should lead a summary discussion about the meaning of
the results of the entire terrestrial study. The following questions can be used during
closure with students:
A. Abiotic Factors
Why are limiting factors so crucial for plant growth, e.g. pH levels of N, P, and K, soil
particle size and type, and the soil’s ability to percolate?
How were the pH, N, P, and K levels different between the transect lines? Did those line
areas have different kinds of plants?
Which transect lines had the most favorable and the least favorable conditions for good
plant growth? Consider soil chemistry type (N, P, K, pH) and soil type (clay, sand, silt,
loam). Explain and describe the factors upon which your answer is based. How could you
improve the worst soil conditions?
How do severe weather conditions, such as torrential rains, change the ability of the soil to
percolate (absorb water)? What happens to the plants?
How do plants help the soil environment cope with limiting factors such as excess
moisture (heavy rain or floods)? Consider the ways plants are used by humans as ground
covers in crop rotations, landscaping and tree farms. What would happen to the soil if all
the plants along the transect lines were killed by disasters such as diseases or fires?
B. Biotic Factors
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Review your list of animals and plants found along the three transect lines. How were the
dominant plant and animal species different among the three transect lines? How do the
plant types change along the transect lines (consider height, leaf size, diversity of species
etc.)?
What limiting factors (light, moisture, soil type etc.) do you think contribute to the success
of the dominant plant and animal? How?
Which limiting factors could you change to make the habitat more suitable for nondominant plants or animals, enabling another to become dominant (more numerous)?
If you were able to examine larger quadrants (10 square meters), would your results of
animal counts change? How? Consider the territory requirements of large animals.
Review the food webs constructed with the dominant plants (producers) and dominant
animals (consumers). What happens to the food web if limiting factors are altered, and
the dominant plant dies? What would happen to the food web if the dominant animal is
over-produced, and more of its offspring survived than usual? Consider diets, population
rates, and space requirements.
C. Additional Questions for Lesson Closure
How did the limiting factors of soil and air temperatures, humidity, and moisture change
along the transect lines? Were there differences in the readings taken at various heights
and depths? Does that change the environment for the creatures living there?
Compare the amounts of light received at ground level along the three transect lines. How
was it different? What could block the light? How could cloud cover affect the light
readings? How might the amount of light received at the sites change from day to day, or
season to season, or in five to ten years? How would living creatures cope with these
changes?
Which transect line had the greatest variety of habitats (different kinds of places for plants
and animals to live)? Which had the least variety? Describe how these contrasting areas
differ physically from one another (light, moisture, humidity, temperatures, terrain etc.).
Consider that more variable climates produce more variable living areas for more
creatures.
Compare the various tree diameters and heights found along the transect lines. Which
transect line appears to have the most established ecosystems or habitats? Why? How
do you know? How would time and human disturbance affect this pattern?
What kinds of limiting factor conditions (benefits and problems) can tall parent trees create
for their seedlings or other creatures (hint: food sources and shelters).
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D. Endangered Species Closure Activity
The questions under this final section are provided as examples that relate the study to
concept of an endangered species.
Ask your students to define or explain the phrases “endangered species" and “extinct
species." On the chalkboard or overhead projector, compile lists of student responses
under the headings of “endangered" and “extinct." Encourage students to give examples
of animals and plants that they believe may be endangered or extinct.
Ask the students why they believe the examples of creatures they noted are endangered
or extinct. Ask the class to select the descriptive terms, phrases, and examples that best
describe endangered or extinct species, circling them on the board. Using probing
questions, lead the students toward a class definition, allowing the students to rank what
they believe are the class’ best possible responses. Challenge the class with the following
scenario:
Endangered species are experiencing extremely difficult limiting
factors within their environments. If the limiting factors of the
environment become excessively demanding, or change too
quickly, some species can no longer cope, and will face
extinction. How can humans alter limiting factors? Should we
do so?
Depending upon your time frame and class needs, student responses can be written
either individually or in small groups, or discussed verbally using an open forum format.
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