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Course: Unit 7: 03.411 Natural Resources Conservation Forest Resource Management Lesson 6: Physiology of a Tree QCC: ................................................................................................. 168, 389, 412 Objectives: 1. 2. 3. 4. Describe the physiological processes of tree growth. Explain tree growth. Explain tree diameter. Describe the methods of reproduction. Teaching Time: 1.5 hours References: Holland, I.I., Rolfe, G.L. Forests and Forestry. 5th Edition. Interstate Publishers, Inc. Danville, IL. 1997. Union Camp Corporation. Union Camp Corporation Agricultural School Forest Lesson Guide. Lesson IV. Central Region Agricultural Office. Materials and Equipment: Increment bore Diameter cutting of pine logs Overhead projector Transparency 7.6.1 and 7.6.2 TEACHING PROCEDURE Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 1 Georgia Agriculture Education Curriculum Introduction and Mental Set Show students various photographs of trees and ask them to guess the age of the tree. Record their guesses on the board. Ask them what criteria they can use to determine the trees= age. What is the distinguishing mark on a tree that allows us to know its age? Lead the students to the fact that the annual ring is the answer. Discussion 1. How is an annual ring formed? A. By division of the cambium B. Each ring is composed of two cell walls: Summerwood - a darker-colored area of small, dense, heavy walled cells. Springwood - a lighter-colored area of large, thin-walled cells C. The difference between the summerwood and springwood cell walls creates the ring. Show the transparency AThe Trunk@ from the SFLG Lesson IV. 2. Distribute a pine wood cross section and have the students count the age of the specimen. 3. Why do annual rings vary in width? A. Closeness to other trees (the closer to other trees; the closer the rings) B. Rainfall amount (the more rain, the further the rings are apart) C. Drought D. Natural disasters - fires, insect damage, etc. 4. Activity Have students do several increment borings on several trees at different heights. Determine the age of the tree. 5. Why do you get different ages for the same tree? A. The level of the boring is crucial to getting an accurate age reading. B. Readings are truer the lower on the tree they are taken. How do trees reproduce? A. Seed - Most trees reproduce by this method B. Sprouts C. Suckers 6. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 2 Georgia Agriculture Education Curriculum 7. What are the parts of a monocot and dicot seed? A. Display and discuss transparency 3.2.1 B. Seed coat C. Embryo D. Stored food $ Endosperm $ Cotyledons 8. What is a complete flower? A. Display and discuss transparency 3.2.2 B. Contains the pistil, stamen, sepals, and petals C. Identify the plant=s reproductive parts $ Stigma, style, ovary for the pistil $ Anther and filament form the stamen 9. What is an incomplete flower? A flower that lacks either a pistil, stamen, sepals (calyx) or petals (corolla) 10. What are monoecious and dioecious flowers? A. Monoecious flowers contain both the male and female reproductive parts. B. Dioecious male and female flowers are produced on separate trees. 11. How are seeds dispersed? A. Wind B. Birds and other animals C. Water D. Man Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 3 Georgia Agriculture Education Curriculum SUMMARY How are trees reproduced? Explain how trees grow. Review how to determine the age of a tree Evaluation Laboratory activity - increment boring Written quiz Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 4 Georgia Agriculture Education Curriculum 3.2.1 PARTS OF THE SEED Two Basic Types Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 5 Georgia Agriculture Education Curriculum 3.2.2 PARTS OF THE FLOWER Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 6 Georgia Agriculture Education Curriculum Ways that Tree Stands Regenerate a. Seeding (natural or direct) b. Stump sprouting c. Planting of seedling Photosynthesis The leaves of a plant use sunlight, carbon dioxide, chlorophyll, and water to produce carbohydrates. Oxygen is given off as a by-product Carbohydrates, including sugars and starches, are later converted to fat and proteins. Fats and proteins are used as food for growth and respiration or are stored in the plant for later use. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 7 Georgia Agriculture Education Curriculum Growth of a Tree Trees begin growth in the spring when the temperature is warm enough. Growth is slower in the summer because of the hot, dry weather. Cells are the building blocks of trees. Root tips, twigs, and branches increase in length when cells become longer. The tree increases in diameter when cells under the bark divide. New growth from under the bark forms the annual ring. One ring is produced each year. The age of a tree can be determined by counting the Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 8 Georgia Agriculture Education Curriculum number of rings from the center out to the edge of the tree. The width of the growth ring indicates the tree’s growing conditions that year. Forest Stratification and Life Zones Emergent- a tree that grows above the general level of the forest canopy. These tallest trees of the forest are exposed to stronger sun and winds than trees in the sheltered levels below. Canopy- the level just below the emergent level. It forms the roof of the forest with the crowns of the dominant trees and other vegetation. Life at the canopy, is host to a broad spectrum of animals including birds, small mammals, and insects. Understory- the area below the canopy, which comprises shrubs, snags, and small trees. This level receives little light. Many of these plants tolerate shade and will remain at this level; others will grow and replace older trees that fall. Th understory life zone provides shelter and habitat for larger mammals including foxes, raccoons, deer, and bears as well as many species of birds, insects, and spiders. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 9 Georgia Agriculture Education Curriculum Forest floor- the lowest level of the forest, which is made up of tree seedlings, dead leaves and needles, grasses, ferns, flowers, fungi, and decaying plants and logs. The forest floor is home to a multitude of organisms, especially small mammals (mice, voles, rabbits, etc.), frogs, turtles, newts, salamanders, insects, grubs, maggots, spiders, other invertebrates, and microorganisms that support decomposition. Groundnesting birds, such as winter wrens, ovenbirds, and quail may also be found here. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 10 Georgia Agriculture Education Curriculum A Look at Competition Trees complete with each other and with other plants in the forest. They vie for sunlight, water, nutrients, and space to grow. Trees occupy the forest canopy, the understory, and the forest floor (as seedling), with roots that can be deep or spread widely across the forest floor. The forest canopy is formed by the branches and leaves from the tallest trees. The understory is the middle layer where shorter trees and shrubs grow. The third layer, the forest floor, is made up of seedlings, grasses, ferns, fungi, decaying plants and logs, and surface- and below- ground- dwelling animals and microorganisms. Trees can be classified according to the position they occupy in the forest canopy or understory. Such a system measures how well a tree has grown relative to its closest competitors. Generally, trees that get the most sunlight will grow fastest. The five classes of forest are: Dominant- Dominant trees have crowns (tree tops) that rise above the general canopy level. They get full sunlight from above and from all sides. Co-dominant- Co-dominant trees make up the canopy level. Their crowns receive overhead light, but dominant and other co-dominant trees restrict some side sunlight. Intermediate- Intermediate trees also occupy the canopy level, but receive sunlight only from above. Suppressed- Suppressed trees receive no direct overhead or side sunlight. They usually are slow growing and may be weak. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 11 Georgia Agriculture Education Curriculum Dead trees (snags)- These can be found in the canopy, understory, or forest floor. Not all trees require direct sunlight to grow. Some trees, called shade tolerant, grow well underneath other trees. Often, they will be the second forests growing under an established forest. Many common trees, such as maple, beech, some oaks, hemlock, and firs, are shade-tolerant. Shade-intolerant species grow in direct sunlight. Often, they are the first trees to grow in an area following disturbance. Many common trees, such as pines and aspen, are shade-intolerant. The five classes of forest are: Dominant- Dominant trees have crowns (tree tops) that rise above the general canopy level. They get full sunlight from above and from all sides. Co-dominant- Co-dominant trees make up the canopy level. Their crowns receive overhead light, but dominant and other co-dominant trees restrict some side sunlight. Intermediate- Intermediate trees also occupy the canopy level, but receive sunlight only from above. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 12 Georgia Agriculture Education Curriculum Suppressed- Suppressed trees receive no direct overhead or side sunlight. They usually are slow growing and may be weak. Dead trees (snags)- These can be found in the canopy, understory, or forest floor. Course 3.411 Natural Resources Conservation Revised August 2000 Unit 7, Lesson 6 13