BIO120H1 Lecture Notes - Lecture 22: Intermediate Disturbance Hypothesis, Pioneer Species, Fire Ecology
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BIO120H1 Full Course Notes
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Lecture 22 spatial ecology, plant communities, and disturbance. Role of disturbance type, frequency, and size. Community dynamics: predictable successional change in plant communities: Pioneer species get in first (from dispersal or seed bank in soil) Soil-building processes and shade thought to be critical. Happens at many levels, but most heavily studied in human-impacts landscapes in eastern north. Vegetation changes spontaneously as the vegetation itself modifies the environment. Ends at climax stage, stable equilibrium, no more change. Primary succession: new substrate created, no pre-existing vegetation undergoes a disturbance. Disturbance = discrete event that causes abrupt changes in ecosystem, community, population; sets back succession. Puts out flows of lava that kill everything in its path. After cooled, well-studied successional sequence of pioneer plants. Seeds found a rare area where they could take root. Time goes by, breaks down lava into solid chunks, real collection of woody plants. Bird feces brings more seeds to the area.
