LESSON 2 A History of Succession BIG IDEAS NUTSHELL In this lesson, students work in small groups • Forests differ in composition and structure. to create a descriptive timeline that illustrates These are both affected by biotic (e.g., animals, how Wisconsin’s forests have changed plants, humans) and abiotic (e.g., soil, moisture, throughout history in response to disturbance. sunlight, climate) factors. (Subconcept 2) To gather information for the timeline, students • Ecosystems are continually undergoing natural listen to a short presentation on Wisconsin’s change. This natural change occurs through natural history, read passages dealing with such processes as long-term evolution or Native American relationships with the forest, through relatively short-term processes such and watch a video about influences on as succession, in which one plant community forests since European settlement. Groups gradually supplants another. (Subconcept 13) then use a Wisconsin Land Cover Map to • Ecosystems are dynamic and altered by discuss the changes that have occurred in natural or human disturbance. Disturbance land use since European settlement. Students plays an ongoing role in ecosystem structure use the timeline and tree characteristics to and function. (Subconcept 14) deduce changes in the distribution of certain tree species. In conclusion, students discuss OBJECTIVES current causes of change in Wisconsin’s Upon completion of this lesson, students will forests and discuss how the causes fit into be able to: the context of the forests’ disturbance history. • Describe the process of forest succession using the terms “change,” “primary succession,” “secondary succession,” “composition,” PROCESS SKILLS “structure,” “disturbance,” “events,” and Essay writing, Map interpretation, Multimedia “large-scale forces.” interpretation, Timeline development • List some of the major causes of forest ecosystem change in Wisconsin over the LESSON/ACTIVITY TIME last 64 million years. • Total Lesson Time: 275 minutes • Describe, in general, the natural features and • Time Breakdown: current land use patterns in Wisconsin. Introduction ...............................45 minutes • Explain why the distribution of specific tree Activity 1....................................30 minutes species in Wisconsin has increased and Activity 2....................................30 minutes decreased throughout history. Activity 3....................................50 minutes Activity 4....................................40 minutes • Identify and describe the current causes Activity 5....................................30 minutes of forest ecosystem change in Wisconsin. Activity 6....................................25 minutes SUBJECT AREAS Conclusion ................................25 minutes Language Arts, Social Studies (Geography, TEACHING SITE History) Classroom 40 Lesson 2: A History of Succession LEAF Guide • 9-12 UNIT MATERIALS LIST FOR EACH GROUP (5 TOTAL) • Overhead of Teacher Page A1, Primary • Copy of either Student Page 2A, Tree Profile Succession Diagram Card - Red Pine OR 2B, Tree Profile Card - • Overhead of Teacher Page A2, Secondary Jack Pine OR 2C, Tree Profile Card - Succession Flow Chart Quaking Aspen OR 2D, Tree Profile A Card - Black Ash OR 2E, Tree Profile • Copy of Teacher Page 3, Pre-human Card - Sugar Maple Influences FOR EVERY 2 STUDENTS • Overhead of Teacher Page A4, Before the Ice Age • Copy of Student Pages 1A-B, Native American Land Use • Overhead of Teacher Page A5, The Ice Age FOR THE CLASS • Overhead of Teacher Page A6, The • Several pieces of poster paper Glaciers Recede A • Markers • Overhead of Teacher Page 7, Native American Settlement • Scissors • Overhead of Teacher Page A8, Forest • Forest Story video (DVD provided by LEAF) Disturbance Timeline • Chalk/marker board • Overhead of Teacher Page A9, Example • Ten sheets of 8.5" X 11" paper Disturbance Timeline (White Pine) • Tape • Copy of Teacher Page A10, White • Rulers Pine History • Assorted colored pencils • Copy of Teacher Page A11, Tree Histories • Five small, irregularly shaped objects • Overhead of Teacher Page A12, Snapshots • Five copies of Student Page 3, Example of Change Tree Profile - White Pine TEACHER PREPARATION • Wisconsin Land Cover Map poster (provided Become familiar with the information on by LEAF) Teacher Page A3, Pre-human Influences. FOR THE TEACHER LEAF Guide • 9-12 UNIT Lesson 2: A History of Succession 41 VOCABULARY Composition: The species that constitute a Ice Age: The last geologic period, the Quaternary plant community. Period, which started 1.8 million years ago and Disturbance: A natural or human action is characterized by the cyclical advance and that causes change in forest ecosystems by retreat of glaciers in North America. damaging or killing some existing plants (e.g., Large-scale Forces: Broad social trends or fire, flooding, logging, insect infestation, wind). environmental forces that shape events and Events: Social or environmental influences cause widespread change on the landscape that affect disturbance patterns and cause (e.g., climate change, mountain formation, regional changes (e.g., glacial advance, evolution, industrialization, human population human migrations, social policies). growth and expansion). Forest Regeneration: The process of Primary Succession: The establishment renewing forest cover through natural or of vegetation in an area that lacks biologic human establishment of trees. communities, soil, and immediate sources for plant reproduction. Glacial Outwash: Rock material composed mostly of sand-sized particles; transported by Secondary Succession: The establishment a glacier and deposited by meltwater as the of vegetation in an area that has some plant glacier retreated. remnants capable of reproduction. Glacial Till: Rock material composed of larger Stress: An environmental factor that gradually rocks and boulders; transported by a glacier weakens organisms (e.g., air pollution, water and deposited directly by the ice. pollution). Glaciation: The advance over land of large Structure: The horizontal and vertical ice masses from the poles of Earth; occurs distribution of layers in a forest, including in cycles as global temperatures cool. height, diameter, and species present. Succession: The change from one biologic community to another over time. BACKGROUND INFORMATION FOREST SUCCESSION Daniel Botkin, in his 1990 book Discordant Changes that forests undergo are part of a Harmonies: A New Ecology for the 21st Century, process called forest succession. Succession wrote that, “change now appears to be intrinsic is a change in forest composition and structure and natural at many scales of time and place in over time and is often defined as a transition the biosphere.” This statement summarizes the from one biologic community to another. shift in thinking that ecologists have introduced to forestry. Forests across the landscape have Change in forests can be caused by the natural changed throughout history, are changing today, aging and dying of plants or can be caused and will continue to change. by disturbances. Disturbances are forces that affect the structure and composition of a forest. 42 Lesson 2: A History of Succession LEAF Guide • 9-12 UNIT They include fire, wind, logging, floods, drought, Common disturbances that can cause secondary insect infestation, disease, animal browsing, succession include fire, logging, insect infestations, etc. Disturbances can be influenced by other animal browsing, wind, and flooding. natural and/or human events. Secondary succession also occurs in the Large-scale forces, both social and absence of major disturbances. Time is a major environmental, are exerted over large factor in succession, and as forests age, the areas for long periods of time and shape environmental conditions within them change. events and ultimately, disturbances. These This can include amount of shade, density of the forces include things such as climate change, understory, soil conditions, and moisture levels. evolution, plate tectonics, human population When old trees die, it is likely that the tree that growth and expansion, industrialization, and grows into its place in the canopy will be of a more recently, globalization. Natural and social different species – a species more adapted to the events occur in response to these forces and conditions present at that time. In this way, forests ultimately shape the disturbance patterns in can change even without major disturbances. forests. Natural events include things such as volcanic eruptions, glaciation, earthquakes, The changes that take place in both primary and extreme weather patterns. Human events and secondary succession depend on the include things such as war, social movements, characteristics of the trees, plants, animals, migrations, and settlement. and other organisms present. Using trees as an example, some trees are tolerant of shade To understand why forests change, it is (e.g., sugar maple, eastern hemlock, beech) necessary to understand the relationship and some trees need full sunlight to grow (e.g., between social and environmental forces, aspen, birch, jack pine, red pine, cherry). As events, and disturbances. To understand how shade conditions change in forests, the trees forests change, it is necessary to understand present will change. This is true for all of the how trees, plants, animals, and other organisms conditions in the forest, including moisture, respond to different disturbances. soil type, disturbances, climate, diseases,