BISC 313 Lecture Notes - Lecture 12: Henry Chandler Cowles, Keystone Species, Primary Succession
1 Nov 2017
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Hot air that burns forests to ash, blew down trees for miles, covered landscapes with ash, filled spirit lake with debris, killing all aquatic life. Elk bounced back quickly because of the vegetation available soon after the eruption. Pocket gophers tunnel underground and mix the nutrients in the soil. Elk collapse the tunnels and allow amphibians to take shelter in the tunnels. Succession is the change in species composition in communities over time. Typically acute factors; ex: volcanic activity, hurricanes, storms, floods. Disturbance: events that injure or kill some individuals and create opportunities for other individuals. Stress: abiotic factors that reduce growth, reproduction, or survival of individuals. Typically chronic factors; ex: temperature, chemical composition, water supply, chemical composition. Biotic interactions can result in replacement of one species with another. Disease can initiate community change by causing death or slow growth of a species. Ecosystem engineers or keystone species can influence community change.
