Unit 7: Fire Ecology

Lesson Plan

Objective To provide an opportunity to expand or reinforce understanding of basic ecological concepts and apply that understanding to fire ecology. Background Ecology is the study of the interrelationships among all living organisms (biotic) and the nonliving elements (abiotic) in and affecting our world. Biotic components, live and die; most abiotic components are in a continuous cycle of building up and being reduced. These ebbs and flows make life possible by seeking a balance among all components, living and nonliving. Most plants utilize nutrients from the soil, air, and water combined in the presence of sunlight to produce food through the process of photosynthesis. While herbivores eat these plants, carnivores eat the herbivores and other carnivores, and omnivores eat some of both - forming food chains. In the end, decomposers break down all that dies, returning it to the land, water, and air (as gases) for plants to again use as nutrients. Like a giant spider's web, all of these are linked to form food webs. Each plant and animal has its own niche (the role it plays) in its habitat (or life space). Groups of plants and animals find similar habitats suitable; these associations are often called communities. A group of communities, including their biotic and abiotic components, that are linked by energy and nutrient flow, are said to be an ecosystem. Communities and ecosystems are constantly changing, evolving through the process of succession (one community reacting to and being replaced by another). Many disturbance forces, including fire, impact these changes. Fire ecology is a branch of ecology that studies the origins of wildland fire and its relationship to the living and nonliving environment. Fire is studied as a natural process operating as a component of and ecosystem. To understand an ecosystem requires looking beyond the ecosystem's present state. Full understanding includes and investigation of the ecosystem's origin, the cycles the ecosystem progresses through, and possible future stages. Fire, similar to floods, earthquakes, storms, etc. can be viewed as one means of promoting changes in an ecosystem. There are three key concepts important to understanding fire ecology - fire dependence, fire history, and fire regime. In the 1930s, researchers began to challenge the negative notions about wildland fire and this new thinking, prevails today. They argued that fire was essential to many plant and animal communities. For example, in drier ecosystems around the world where there is not enough moisture to help in the decay of dead plants, fire is required to break down and help recycle the nutrients. This concept is fire dependence and applies to natural communities that are adapted to and rely on the effects of fire to make the environment more hospitable for that community's plants and animals. For example, fire kills some large plants and prepares the soil for seeding by making nutrients more available for plant uptake. As a result, competition is reduced from other species that would have absorbed needed nutrients or shade out sunlight the new plants require. Fire history is described as how often fires occur in a given geographical area. Trees actually record fire history. Each year a tree adds a layer of cells, increasing the width of its trunk. When a fire passes through a forest, trees may be only scorched. A layer of charcoal remains on a living tree and, in time, is enveloped by a layer of new growth creating fire scars. These fire scars provide a record that scientists can use to determine when in the history of the scarred tree a fire occured. Fire scarred trees that are petrified often retain these fire scar records as fossilized charcoal or fusain. The role fire plays in an ecosystem varies with the characteristics under which the ecosystem has evolved. This role is known as fire regime. The interactions of humidity, fuels, and ignition sources determine the fire regime for a particular land area. A fire regime is a function of the frequency of fire occurence, the fire intensity, and the amount of fuel consumed. Both frequency and intensity of fire vary but are interdependent. Frequency of fire is largely determined by the ignition source(s) and the duration and character of weather that favor the spread of fire. Intensity of fire is determined by the quantity of fuels available and the fuels' combustion rates. The interaction between frequency and intensity of fires is influenced by wind and topography. The greater the wind velocity and the steeper the terrain, the more intensely the fire will burn. Fire ecology is a major subject of study in a number of universities around the world. Students who are interested in becoming a fire ecologist must study physical, chemical, and biological sciences, and mathematics. The study of wildland fire also requires and understanding of the human dimensions of the issue. Students must become proficient in language arts and social sciences. Through creative arts, students gain skills in design, problem solving, and aesthetics. All subjects are important, especially for scientists who work with forces of nature as awesome as wildland fire. Fire ecology is an exciting subject. The more we teach our students about this topic the greater our potential to more effectively manage wildland fire.

Grades 5 - 8: Ecology and Wildland Fire Materials Poster board or flip chart Large index cards, string, scissors, and markers Pencil and paper Activities Define "ecology" on the board. Review what students know about ecological concepts. Terms that should be discussed are: Abiotic Food Web Adaptation Habitat Balance Herbivore Biotic Niche Carnivore Nutrients Communities Omnivore Decomposers Photosynthesis Ecosystems Succession Food Chain   Review concepts from Unit 5 and 6. Explain the following concepts: Fire Adaptation Fire Dependence Fire Ecology Fire History Fire Regime Fire Scars Wildland Fire Create a food web/interdependence game based on a local plant community. Ask students to list plants and animals found in that community. Have the students make a name card for one species they named, and hang that species' name card around their neck. Discuss each species' niche and who depends on whom as a food source, for shelter, etc. Using one piece of string, connect all of the students to their interdependent partners (students may be connected to a number of other partners). Ask students to explain what happens to their species in the case of a wildland fire. Discuss both the positive and negative impacts. (see Unit 9 for additional background information.) Include issues of water and air pollution and impacts on soils. Ask the students what there is more of and what there is less of after a wildland fire. Ask students if they wanted to become a fire ecologist or wildland fire manager, what would they need to study in school? What would they study in college? List their responses and reinforce. Stress how each area of academic study (all subjects at their grade level) prepares them for these most important positions.