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.
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.
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.
Strand: Biology
Specific Lesson Goals:
compare a natural and an artificial ecosystem and suggest ways of assuring their sustainability (e.g. compare a meadow and a lawn);
examine the factors (natural and external) that affect the survival and equilibrium of populations in an ecosystem.
Strand: Biology
Specific Lesson Goals:
compile data on the biodiversity within a natural ecosystem using appropriate techniques and compare the results with those from an artificial ecosystem;
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).
Knowledge:
318-6 explain how the biodiversity of an ecosystem contributes to its sustainability.
331-6 analyze the impact of external factors on an ecosystem.
Skills:
213-3 use instruments effectively and accurately for collecting data.
213-5 compile and organize data, using appropriate formats and data treatments to facilitate interpretation of the data.
212-9 develop appropriate sampling procedures.
Each group will need:
hand lens
garden trowel (or large spoon)
sweepnet (or kitchen sieve)
measuring tape (or metre stick)
strong string (5m)
4 corner stakes (e.g. tent pegs or pieces of wood such as dead, thin branches)
tray (pie plate size)
field guides for the identification of plants (both wildflowers and weeds) and insects
clear plastic (not glass) collecting jars with lids or plastic bags with seal tops
student worksheets
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.
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).
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.
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.
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).
Explain how relative abundance on a four-point scale will be used to identify the occurrence of plant and animal species.
Abundant - The species is easily found in high numbers in the study area.
Frequent - The species is easily found but the number is not the highest in the study area.
Occasional - The species is not always detectable in the study area, but can usually be found in small numbers through persistent searches.
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.
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.
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.
Review the remaining requirements of the assignment.
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 |
Function |
|---|---|
|
Group Leader |
Responsible for overall performance of the group. |
|
Equipment Manager |
Prepares a list of the equipment, instructs others in its use and ensures that it is all returned undamaged. |
|
Data Collector |
Ensure that all data are recorded in appropriate tables. |
|
Identification Coordinator |
Maintains the "library" of identification materials and ensures that organisms are properly identified. |
|
Safety Officer |
Ensures that the group stays together and that safety regulations are followed. |
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.
Provide time for discussion of the follow-up questions.
Conduct a whole-class discussion around the results and these questions. Be sure to include a discussion of native and invasive plants.
Which ecosystem contained the greatest diversity of plants and animals? Explain why.
In which trophic levels are most organisms found in the natural and artificial ecosystems? Explain why.
Account for differences in the relative abundance of plants and animals identified in the natural and artificial ecosystems.
Which ecosystem do you think is more stable? Support your answer.
Predict what would happen if all the plants with the exception of grasses were killed off in each ecosystem.
Compare the advantages and disadvantages of growing native plants vs. exotic plants.
List some well-known invasive species. What are their impacts on the local ecology and economy? Why are they so difficult to control?
List as many food chains as you can for each ecosystem.
Attempt to create a food web for each ecosystem.
What larger animals may be involved in the food web of each ecosystem? What evidence of this involvement do you have?
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?
Completion of worksheets and quality of observations
Observation
Peer and self-evaluation
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.
Design and conduct comparative ecosystem studies for the following undisturbed sites:
wet area versus sunny area of the school ground
coniferous tree area versus deciduous tree area
area with organically rich soil versus area with organically-poor soil
wooded area versus meadow
sheltered area versus windy area
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.
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.
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).
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?
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.
Scout out potential natural and artificial habitats on the school ground and, if necessary, in the nearby community.
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.
Consider contacting your local field naturalists club and ask for volunteers to assist with the supervision and the identification of plant and animal species.
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.
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.
It is recommended that this investigation be conducted in the early fall or late spring.
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.
Andrews, W.A. and Moore, D. Investigating Terrestrial Ecosystems. Scarborough: Prentice Hall Canada. 1986.
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/
Leahy, C. L. and White, R. E. Peterson Field Guide to Insects of North America. Boston: Houghton Mifflin Company. 1987.
Montgomery, F. H. Weeds of Canada and the Northern United States. Toronto: McGraw-Hill Ryerson Limited. 1964.
Newcombe, L. Newcombe's Wildflower Guide. Boston: Little Brown and Company. 1977.
Niering, W.A. and N.C. Olmstead. The Audubon Society Field Guide to North American Wildflowers, Eastern Region. New York: Alfred A. Knopf. 1979.
Parker, Steve. Insects. Toronto: Stoddart Publishing Co. Limited. 1994.
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.
Stokes, Donald W. A Guide to Observing Insect Lives - Stokes Nature Guide. Boston: Houghton Mifflin Company. 1983.
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.
For information on invasive exotic species ranking for Southern Ontario, visit: www.serontario.org/pdfs/exotics.pdf
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.
Predict which ecosystem study site will contain the greatest diversity of plants and animals. Explain your predictions.
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.
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.
Use one of these words to describe the relative abundance of each plant species: abundant, frequent, occasional, rare. Record in Tables 1 and 2.
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.
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.
Record the relative abundance, structural and behavioural advantages to the animals, and their trophic levels/niche in Tables 1 and 2.
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.
Examine the areas for evidence of decomposers. Record your findings in the tables.
Each quadrat is a mini-ecosystem. What evidence do you see of ecological interactions? Record your observations in Tables 1 and 2.
What evidence do you see that humans have had an effect on the mini-ecosystem in each quadrat?
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TIME:______ |
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|---|---|---|---|---|
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Plant / Animal (name or sketch) |
Relative Abundance (a,f,o,r) |
Adaptations |
Advantages to Plant / Animals |
Trophic Level (niche) |
|
e.g. Grasshopper (Dissosteira) |
a |
Biting and chewing mouthparts; hard exoskeleton; wings; jumping legs |
Can feed on vegetation; move freely in open spaces for defense; protected against desiccation |
Herbivore First order consumer |
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Describe ecological interactions which you observed: |
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Describe evidence of decomposers: |
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TIME:______ |
||||
|---|---|---|---|---|
|
Plant / Animal (name or sketch) |
Relative Abundance (a,f,o,r) |
Adaptations |
Advantages to Plant / Animals |
Trophic Level (niche) |
|
e.g. Common Dandelion (Taraxacum officinale) |
a |
Long taproot; bright yellow flower; large broad leaves |
Seek water; attract pollinators; capture sun and shade out grass |
Producer |
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Describe ecological interactions which you observed: |
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Describe evidence of decomposers: |
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