From Seed to Seed:
Plant Science for K-8 Educators
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From Seed to Seed: |
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Activity 22: All Bogged Down Grades: 5-8 Associated Lesson Topics:
National Standards: Planting the Seed... How many of you have traveled to different parts of the country or world? Did you notice when you were traveling if the plants looked the same as the plants that we have here? What factors do you think might determine where a plant will or will not grow? Can you think of some plants that are found only in certain parts of the world? How do those plants "fit in" with the environments in which they live? Teacher Information: Based on the National Science Education Standards, in grades 5-8, students should explore the interrelationship between plants and their environment. In this activity, students explore the topic of carnivorous plants. Specifically, what effect does the environment have on the types of plants that are present? A bog is a type of wetland. The difference between a "typical" wetland and a bog is that bogs are stagnant. In other words, the inflow and outflow of water is restricted. Bog vegetation is dominated by sphagnum moss, sedges, and rushes. These plants form a mat of vegetation that prevents sunlight from reaching the stagnant water. As a result, algae and other aquatic plants are unable to grow and produce oxygen. Bogs are also acidic. Sphagnum moss accumulates carbon ions and, in return, releases hydrogen ions. The release of hydrogen ions decreases the pH of bogs, causing them to be acidic. The inadequate supply of oxygen combined with high acidity produces a mineral-deficient atmosphere because bacterial decomposition of organic matter is impeded. As a result, bog plants have to get their nutrients from somewhere other than the soil. "Carnivorous" plants are specially adapted to grow in bogs. Only about 20 plant species are adapted to these conditions. Instead of retrieving their nutrient supplies from the soil, carnivorous plants have developed elaborate traps to lure insects. Instead of animals eating them, these plants eat animals!
Procedure:
Harvesting the Crop... What observations did you make about the two ecosystems? What are some differences between the two ecosystems? What are some similarities? Do we see the same quantity of plants in both? Do the plants growing in the two ecosystems have different growth forms? What about the environment might affect the types of plants we see? At this point you can discuss bogs, their nutrient deficiencies, and carnivorous plants. Did you notice any plants in the bog that have a unique structure? What do you think these plants might use these unique structures for? If you do not have access to a bog, a comparative study such as this can involve any two ecosystems. For example, comparisons can be made between deciduous and coniferous forests. Plant adaptations are visible everywhere! Plants that grow in shady places, for instance, often have wider leaves (to collect as much light as possible), whereas those that grow in sunny places often have narrower leaves (to reduce water loss). If, however, you are determined to use a bog ecosystem and do not have access to one, you and your students can build a model bog habitat in your classroom or schoolyard. Below are instructions for doing so. By building a bog, students will discover what makes bog ecosystems unique! Building a Bog (from Hanif, M., Science and Children,
April 1990, pp. 25-27)
Procedure:
Bog Maintenance
Sources
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