Intermediate Disturbance Hypothesis

Lab: Intermediate Disturbance Hypothesis

Using a model of succession from grasses to trees, students start out by observing a successional sequence without disturbance. Then they get to start setting fires. By systematically varying the size and frequency of fires, they recreate the standard textbook graph of the intermediate disturbance hypothesis showing that species diversity is highest at intermediate levels of disturbance. In an open-ended advanced section of the lab, students can alter the susceptibility of different species to burning and their succession rate to see how these factors influence diversity. This lab is often cited as a favorite by both instructors and students for its content, and also for the graphics that display red fire rushing through the forest. Although the ideas are typically introduced in upper-level ecology courses, the lab is straightforward and emphasizes data collection and graphing, making it applicable for courses for students without a scientific background.
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Level: Intro, Sophomore/Junior
Key Concepts: Disturbance; Intermediate Disturbance Hypothesis; Scientific modeling; Succession
Courses: Community Ecology; Ecology; Intro Bio: Eco/Evo/Genetics; Intro Bio: Non-majors

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