This activity was in the 2001 Particles and Prairies Sampler. See the 2006 Sampler
Invertebrates in the Prairie and Forest
Invertebrates - Fermilab Quadrat Study - Prairie - School Quardat Study - Baked Potato
PURPOSE: To compare numbers and types of invertebrates that can be found within the vegetative litter or just at or below the soil surface of the prairie and the forest.
OBJECTIVES: Students will:
- Identify six major groups of terrrestrial invertebrates
- Use a dichotomous key.
- Compare the invertebrate fauna of the prairie with that of the forest.
BACKGROUND: One of the most remarkable characteristics of the flowering prairie is its capacity to maintain itself. It is distinguished by the fact that it provides a rich food source for various forms of animal and plant life by the fact that its remains do not accumulate permanently. There is an inevitable piling up of materials on the prairie floor that remains until the area is burned. This activity is intended for a prairie that has not experienced fire for several years. Refer to Fire Ecology lab for the importance of the Prairie Fire.
The surface of the forest floor may appear to be a lifeless carpet of refuse and dead leaves, but immediately below the top layer are the decaying remains of other seasons, occupied by a busy community of tiny organisms. Deeper still, the humus, dark spongy material formed from the litter, is honeycombed with passageways and burrows of insects, worms, moles, and the roots of plants.
The invertebrates found within the vegetative litter or just at or below the soil surface are a major part of an ecosystem that often goes unnoticed. These animals represent a wide variety of feeding strategies and habitat requirements. A familiarity with the major invertebrate phyla found on the forest floor and the base of the prairie will help one to understand the complexities of these systems.
MATERIALS:
- Particles and Prairies Invertebrate Field Guide
- Particles and Prairies Invertebrate Dichotomous Key
- Berlese Funnel Setup
- Particles and Prairies Invertebrate Wanted Posters
- Sampling equipment such as:
- Trowels
- Assorted bags or containers
- Plastic petri dishes
- Probes (may be as simple as plastic straws cut on an angle)
- Magnifying lenses (reflective light or dissecting microscopes are recommended.
PROCEDURE:
1. Select the sampling sites. (Invertebrate analysis using a Berlese funnel can be done in a variety of habitats. If access to a prairie or a forest is not available, two other ecosystems may be substituted.) Each student team (a four member team is suggested) needs a small defined plot to sample. Sample plots may be defined with string, small hoops or other devices that can be standardized. A suggested plot size is about 30 cm square.
2. Using the sampling equipment, the student should collect all the material within the plot including about one centimeter of the surface soil. The students should place the sample in a plastic bag or container and label the sample with the date, location and any other pertinent data you wish to include.
3. Set up the Berlese funnel apparatus according to the diagram.
The students should empty the contents of their sample bags into the funnel. Label information should follow the sample. (Multiple Berlese funnel setups are useful for speeding up the collection process.) The lightbulb should be positioned above the material close enough to provide heat and light, but not so close to promote a fire. Keep the light burning day and night for at least 24 hours. Depending on the type and amount of material collected, several days or more may be needed to drive all of the invertebrates into the collecting bottle.
4. Using a spoon, transfer small quantities of the collected material to open petri dishes. One collection jar should provide enough material for four or more dishes. Replenish the alcohol as it evaporates since it preserves the specimens and, when using magnification, provides uniform light diffraction.
5. Using magnification and a probe, students should analyze the material for invertebrates. Students should record the number and phylum for each invertebrate. Have the students sketch the organisms they find.
Use the data sheet provided or have your students design their own.
DISCUSSION QUESTIONS:
- What are the differences and similarities between the invertebrate populations of the prairie and the forest?
- Do the types of invertebrates found indicate certain environmental conditions? certain fauna or flora? (Life history research is helpful here.)
- What questions can you pose about invertebrates, biomass and energy transfer in these ecosystems? What measurements might you make to answer your questions?
EXTENSION: Collect leaf litter from an area aound the school. (vacant lot, forest, etc.) Compare organisms.
