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Community Ecology. Ecological Succession. Disturbance. An event that changes a community May include: Removal of organisms Alteration of resources available Examples: Storm Fire Overgrazing Human activity. Intermediate Disturbance Hypothesis.
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Community Ecology Ecological Succession
Disturbance • An event that changes a community • May include: • Removal of organisms • Alteration of resources available • Examples: • Storm • Fire • Overgrazing • Human activity
Intermediate Disturbance Hypothesis • Moderate levels of disturbance creates greater opportunities/conditions for species diversity • opens up habitats for less competitive species • Doesn’t damage the environment beyond recovery
Ex. Yellowstone National Park Fires • Fires allowed new species to grow and a new generation of Lodgepole pines to grow
Ecological Succession • Progressive sequence of changes in the species that make up a community Image taken without permission from http://bcs.whfreeman.com/thelifewire/default.asp?s=&n=&i=&v=&o=&ns=0&uid=0&rau=0
Primary Succession • Process begins in a lifeless area where soil has not yet formed • Ex. Glacier retreating reveals volcanic rock • Lichens & mosses grasses & shrubs trees
Secondary Succession • Existing area has been cleared by some disturbance– but the soil is still intact • Ex. Yellowstone fires, cornfield abandoned
Image taken without permission from http://www.sbs.utexas.edu/levin/bio213/ecosystems/ecology.html