Teacher’s Corner Lesson Plans
Helping Teachers and Students Make the Most of
their Outdoor Classroom
www.evergreen.ca
Bringing Nature to our Cities
Investigating Biological Communities in Natural and
Artificial Ecosystems
Sandra McEwan
Grade level: Grade 10.
Provincial curriculum links: Ontario.
Subject: Science.
Keywords: Quadrat, ecosystem, artificial ecosystem, biotic study, comparative ecosystem
study, habitat, niche, population, community, trophic (feeding) level, food chain, food web,
adaptation.
Description
In this activity, students will use the quadrat method to survey and compare plant and
animal populations that exist in natural and artificial ecosystems on the school ground or
in the local community. Students will estimate the relative abundance of organisms, identify
their ecological relationships and describe how they are suited to a particular habitat.
Curriculum Framework
This lesson is linked directly to the learning expectations described in the Ontario Curriculum for Grade 10 Science.
The learning expectations are also broadly applicable to other Canadian curricula, including
the Pan-Canadian Science Curriculum.
A: Ontario Curriculum Grade 10 Science (SNC 2D)
Strand: Biology
Specific Lesson Goals:
ˆ compare a natural and an artificial ecosystem and suggest ways of assuring their
sustainability (e.g. compare a meadow and a lawn);
ˆ examine the factors (natural and external) that affect the survival and equilibrium of
populations in an ecosystem.
Investigating Biological Communities
2
B: Ontario Curriculum Grade 10 Science (SNC 2P)
Strand: Biology
Specific Lesson Goals:
ˆ compile data on the biodiversity within a natural ecosystem using appropriate techniques and compare the results with those from an artificial ecosystem;
ˆ assess the impact of technological change on an ecosystem (e.g. the introduction of
fertilizer and pesticides to soil; the introduction of a genetically engineered plant; the
effect of polluted water or air on plants and animals).
C: Pan-Canadian curriculum
Knowledge:
ˆ 318-6 explain how the biodiversity of an ecosystem contributes to its sustainability.
ˆ 331-6 analyze the impact of external factors on an ecosystem.
Skills:
ˆ 213-3 use instruments effectively and accurately for collecting data.
ˆ 213-5 compile and organize data, using appropriate formats and data treatments to
facilitate interpretation of the data.
ˆ 212-9 develop appropriate sampling procedures.
Preparation
Preparation time: Approximately 30 minutes to collect materials, photocopy student
worksheets, read educator notes (provided) and review references/resources (as noted
below), plus time to locate study areas.
Length of lesson: Approximately 200 minutes for class discussions and field trip.
Resources required:
Procedure
Note to teacher: If your school ground has a good place for students to gather together, you
may want to do steps 1-8 outside, or split the introductory time between the school grounds
and the classroom. After all, an explanation of natural and artificial ecosystems may be
easier to convey when you have living examples at hand. When you go out into the field to
do the activity, don’t forget to allow time for students to collect materials beforehand, and
return them afterwards. Students will need notebooks or clip-boards on which to take field
notes.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
3
1. As a class, brainstorm methods of sampling plant and animal populations in terrestrial
ecosystems (e.g. random study plots of consistent size; a systematic arrangement of
quadrats in parallel lines laid out perpendicular to a base line; inventory wildlife for
specific time periods throughout the day / week / month / season).
2. Explain that, in this investigation, the square quadrat method will be used to sample
and compare plant and animal populations living in natural and artificial ecosystems.
Ecologists have discovered that the quadrats need only make up 10% of the total area
of the site being studied in order to obtain reliable information.
3. Use the chalkboard to brief your students on the procedure for laying out a 1m x 1m
quadrat using 4 stakes and 5m of string. The additional metre allows the students to
wrap the string around the corner stake two or three times, instead of cutting it and
tying it.
4. As a class, brainstorm examples of natural and artificial ecosystems in the school
ground and nearby community. Natural ecosystems have not been planned or maintained by humans. Examples include a meadow, a naturally regenerated woodlot/forest, an undisturbed ditch, the natural shoreline of a pond, lake or stream.
Artificial ecosystems have been planned or maintained by humans. For example, a
mowed and fertilized lawn, a garden or field of crops, a previously cut meadow, a
managed woodlot, a reforested plantation. Select a pair of relatively similar natural
and artificial ecosystems to complete a comparative study (e.g. a meadow or unmowed lawn and a mowed lawn; an abandoned ditch and a managed ditch; natural
and managed regenerated woodlots).
5. Explain how relative abundance on a four-point scale will be used to identify the
occurrence of plant and animal species.
ˆ Abundant - The species is easily found in high numbers in the study area.
ˆ Frequent - The species is easily found but the number is not the highest in the
study area.
ˆ Occasional - The species is not always detectable in the study area, but can
usually be found in small numbers through persistent searches.
ˆ Rare - The species is seldom found in the study area.
Do not worry if your students can’t identify all of the plants and animals. A simple
sketch can serve as a substitute for a name. However, if you have field guides on
hand, students can identify at least a few of the plants they find. A typical school
ground lawn has knotweed, plantain, creeping Charlie, chickweed, dandelions and
several species of grass. Familiarize yourself with these plants before the field trip.
6. Demonstrate how to collect animals by sweeping the vegetation with a sweep-net or
kitchen sieve and transferring to collection jars. Stress that all life must be treated
with respect and returned to its original location promptly.
7. Explain how to collect and examine a soil sample. Your students should be able to
identify the common soil animals - earthworm, ant, mite, sowbug, snail, slug, giant
centipede, ground centipede, earwig, carrion beetle.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
4
8. Review the remaining requirements of the assignment.
9. Organize the students into research teams. A group size of no more than 5 or 6 is
best for a single study site. Distribute special tasks as follows:
Special Task
Group Leader
Equipment Manager
Data Collector
Identification Coordinator
Safety Officer
Function
Responsible for overall performance of
the group.
Prepares a list of the equipment, instructs others in its use and ensures that
it is all returned undamaged.
Ensure that all data are recorded in appropriate tables.
Maintains the “library” of identification
materials and ensures that organisms are
properly identified.
Ensures that the group stays together
and that safety regulations are followed.
10. Assign study plots to each research team. Spread them well apart to avoid interfering
with each other. If possible, before your students go outside, place a red painted
starting stake in the ground to mark the location of each study plot.
11. Provide time for discussion of the follow-up questions.
Discussion and Questions
Conduct a whole-class discussion around the results and these questions. Be sure to include
a discussion of native and invasive plants.
1. Which ecosystem contained the greatest diversity of plants and animals? Explain why.
2. In which trophic levels are most organisms found in the natural and artificial ecosystems? Explain why.
3. Account for differences in the relative abundance of plants and animals identified in
the natural and artificial ecosystems.
4. Which ecosystem do you think is more stable? Support your answer.
5. Predict what would happen if all the plants with the exception of grasses were killed
off in each ecosystem.
6. Compare the advantages and disadvantages of growing native plants vs. exotic plants.
7. List some well-known invasive species. What are their impacts on the local ecology
and economy? Why are they so difficult to control?
8. List as many food chains as you can for each ecosystem.
9. Attempt to create a food web for each ecosystem.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
5
10. What larger animals may be involved in the food web of each ecosystem? What
evidence of this involvement do you have?
11. Identify any non-native plant species growing on or near the school ground (e.g. cultivated rose bush). What seasonal maintenance is required to help the plant(s) adapt
to the local conditions?
12. Identify any native plant species growing on or near the school ground (e.g. Black-eyed
Susan). What are the advantages of growing native species? How are these plants adapted
to the local conditions?
Student Evaluation
ˆ Completion of worksheets and quality of observations
ˆ Observation
ˆ Peer and self-evaluation
Enrichment and Extension Activities
ˆ Conduct a comparative study of the abiotic factors for the two ecosystems (e.g. slope,
air temperature, light intensity, wind speed and direction, relative humidity, soil temperature at different depths, soil pH, upper soil profile, percolation rate). Account for
differences between the two ecosystems. Making reference to the biotic and abiotic
factors data, write a paper to illustrate that all parts of an ecosystem are interdependent.
ˆ Design and conduct comparative ecosystem studies for the following undisturbed sites:
ˆ wet area versus sunny area of the school ground
ˆ coniferous tree area versus deciduous tree area
ˆ area with organically rich soil versus area with organically-poor soil
ˆ wooded area versus meadow
ˆ sheltered area versus windy area
ˆ Identify invasive plant species on the school grounds and in the local community (e.g.
buckthorn, purple loosestrife). Research the method of introduction, range, impact
and control measures. Describe the adaptive features that allow the plants to be
highly invasive.
ˆ Research the loss of local wildlife and heritage food varieties in favour of a narrow
range of food crops that are often genetically engineered. Find out which food crops
are predominantly grown; the reasons for the decline in food variety; the benefits
and drawbacks of genetically engineered food crops; and the impact on the local
environment of narrowing the biodiversity of food crops.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
6
ˆ Conduct a class debate on the use of native vs. non-native plants for school ground
landscapes (or for food crops, or for ornamental gardening).
Connections to the Outdoor Environment
Where possible, relate the discussion questions back to the students’ own school ground.
Why is it important to protect or restore biodiversity wherever possible? How diverse is
your school ground, and how could it be made more diverse? What are the external impacts
on the school ground ecosystem, and how do they affect species diversity and abundance
(e.g., salt from roads or parking lot; foot traffic; acid rain)? What about technological
factors such as pesticides and fertilizers?
Educator Notes
ˆ Students should have prior knowledge of the following ecological terms and concepts:
habitat and niche; population, community and ecosystem; trophic (feeding) levels;
the design of food chains and food webs; structural and behavioural adaptations of
organisms (cite examples and explain their advantage); and the ecosystem concept.
ˆ Scout out potential natural and artificial habitats on the school ground and, if necessary, in the nearby community.
ˆ Assemble identification guides and picture keys for wildflowers, trees and shrubs, insects, etc. Check your school library and science department for copies. Otherwise,
try the public library.
ˆ Consider contacting your local field naturalists club and ask for volunteers to assist
with the supervision and the identification of plant and animal species.
ˆ Try to inculcate in your students a respect-for-life ethic. Invertebrates should be
handled with sensitivity. Do not allow your students to harass any vertebrates.
ˆ Try to minimize habitat disturbance during the study. Tell your students to return
all animals and soil to the habitats from which they were taken. This may be an
opportunity to discuss the impact of human disturbances on ecosystems.
ˆ It is recommended that this investigation be conducted in the early fall or late spring.
ˆ SAFETY NOTE: Consult your school board’s policy regarding safety precautions for
outdoor excursions and plan your trip accordingly. Be aware of any students with
allergies to insect bites and plants and ensure they carry the required medications.
Students should wash their hands after handling soil, plants and equipment. Encourage students to wear sunscreen and appropriate clothing (e.g. hat, long-sleeved shirt)
to minimize the damaging effects of sun exposure.
References
ˆ Andrews, W.A. and Moore, D. Investigating Terrestrial Ecosystems. Scarborough:
Prentice Hall Canada. 1986.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
7
ˆ Foster, Steven and James Duke. A Field Guide to Medicinal Plants and Herbs of Eastern and Central North America. The Peterson Field Guide Series. Boston: Houghton
Mifflin Company. 2000/
ˆ Leahy, C. L. and White, R. E. Peterson Field Guide to Insects of North America.
Boston: Houghton Mifflin Company. 1987.
ˆ Montgomery, F. H. Weeds of Canada and the Northern United States.
McGraw-Hill Ryerson Limited. 1964.
Toronto:
ˆ Newcombe, L. Newcombe’s Wildflower Guide. Boston: Little Brown and Company.
1977.
ˆ Niering, W.A. and N.C. Olmstead. The Audubon Society Field Guide to North American Wildflowers, Eastern Region. New York: Alfred A. Knopf. 1979.
ˆ Parker, Steve. Insects. Toronto: Stoddart Publishing Co. Limited. 1994.
ˆ Peterson, R. T. and M. McKenny. A Fieldguide to Wildflowers of Northeastern and
Northcentral North America. The Peterson Field Guide Series. Boston: Houghton
Mifflin Company. 1968.
ˆ Stokes, Donald W. A Guide to Observing Insect Lives - Stokes Nature Guide. Boston:
Houghton Mifflin Company. 1983.
ˆ White, D. J., Haber, E., and Keddy, C. Invasive Plants of Natural Habitats in Canada.
Ottawa: Habitat Conservation Branch, Canadian Wildlife Service. Publication No.
CW-66-127/1993E. 1993.
ˆ For information on invasive exotic species ranking for Southern Ontario, visit: www.
serontario.org/pdfs/exotics.pdf
Worksheets
Student Worksheet
Date:
Group Members:
Natural Ecosystem Study Site:
Artificial Ecosystem Study Site:
In this field study you will use the quadrat method to survey and compare plant and animal
populations that exist in natural and artificial ecosystems.
1. Predict which ecosystem study site will contain the greatest diversity of plants and
animals. Explain your predictions.
2. Use the string and 4 stakes to mark off a 1m x 1m quadrat in each of the study sites.
Describe the ecosystems under investigation.
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
8
3. Use the field guides provided by your teacher to help identify the plants growing in
both quadrats. If you cannot identify a plant, make a sketch or take a photograph.
Record your findings in Tables 1 and 2.
4. Use one of these words to describe the relative abundance of each plant species: abundant, frequent, occasional, rare. Record in Tables 1 and 2.
5. List the structural adaptations for each plant and describe the advantage to the plant.
Look in the field guides for a description of the plant’s root system. Record your
findings in Tables 1 and 2.
6. Sweep the vegetation in your study sites with the sweepnet or kitchen sieve. Transfer
the animals you catch to collection jars. Examine them closely using a hand lens.
With the help of the field guides, record the name of each animal or sketch a drawing
in Tables 1 and 2. Release all animals back to their original sites.
7. Record the relative abundance, structural and behavioural advantages to the animals,
and their trophic levels/niche in Tables 1 and 2.
8. Use the trowel to collect some topsoil and plant litter (the top 4 to 5 cm will do).
Spread the soil sample out in the tray and search for animals. Study them closely
with the hand lens. Record your findings in Tables 1 and 2. Return the soil samples
to the original sites.
9. Examine the areas for evidence of decomposers. Record your findings in the tables.
10. Each quadrat is a mini-ecosystem. What evidence do you see of ecological interactions?
Record your observations in Tables 1 and 2.
11. What evidence do you see that humans have had an effect on the mini-ecosystem in
each quadrat?
Teacher’s Corner — www.evergreen.ca
Investigating Biological Communities
9
Table 1: Terrestrial Biotic Study For Natural Ecosystem Study Site
TIME:
Plant /
Animal (name
or sketch)
e.g. Grasshopper
(Dissosteira)
Relative
Abundance
(a,f,o,r)
a
Adaptations
Biting and chewing mouthparts;
hard
exoskeleton;
wings;
jumping legs
Advantages
to Plant /
Animals
Can feed on
vegetation;
move freely in
open spaces for
defense;
protected
against
desiccation
Describe ecological interactions which you observed:
Describe evidence of decomposers:
Teacher’s Corner — www.evergreen.ca
Trophic Level
(niche)
Herbivore
First order consumer
Investigating Biological Communities
10
Table 2: Terrestrial Biotic Study For Artificial Ecosystem Study Site
TIME:
Plant /
Animal (name
or sketch)
e.g.
Common Dandelion
(Taraxacum
officinale)
Relative
Abundance
(a,f,o,r)
a
Adaptations
Long
taproot;
bright
yellow
flower;
large
broad leaves
Advantages
to Plant /
Animals
Seek water; attract pollinators;
capture sun and
shade out grass
Describe ecological interactions which you observed:
Describe evidence of decomposers:
Teacher’s Corner — www.evergreen.ca
Trophic Level
(niche)
Producer