BIO130H1 Lecture Notes - Lecture 9: Intermediate Disturbance Hypothesis, Secondary Succession, Spatial Ecology
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BIO130H1 Full Course Notes
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Lecture 9: spatial ecology, plant communities and disturbance. Classical successional sequence: 1) weedy r-strategist pioneers 2) goes through temporary non-equilibrium stages 3) ends at climax stage, stable equilibrium, no more change. Primary succession: new substrate and no pre-existing vegetation. Secondary succession: pre-existing vegetation that had a disturbance e. g. fire, windstorm, and logging. Annual weeds perennial weeds woody shrubs trees tree canopy closes in (shade is important) only shade tolerant trees. Drivers of terrestrial succession: 1) soil development n, ph, water retention in primary succession 2) shading in secondary succession where soil is developed 3) may reach stable climax (beech-maple in our region) but often not. No climax reached when lead to spruce-fir forest, acid/sandy soils in pine-oak leaf litter, fireprone ecosystems like grasslands or pine forest at flammable stage, cycling of dominants e. g. a replaces b and then b replaces a, Gap phase succession: in tropical rainforest, large fig tree will create major canopy gap when it falls/dies.
