BIOL 117 Lecture 21: Chapter 21 - Ecology
23 Jul 2016
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Dirt on soil: soil must have organic matter, dirt does not, dirt: ground up rocks/matter, glaciers. Peak of last ice age: 18,000 years ago. Glacier bay alaska: receding, leaves behind dry riverbed. Looking at different areas while moving up valley, landscape left behind can be recorded and allows us to see what end result of succession is because we can see the time vs vegetation differences. Allows us to watch succession occur: glacier receding, barren landscape, mosses and lichens ~ grows and dies, grows and dies, eventually forms thin layer of soil. Herbaceous species begin to grow (non-wood producing plants) along with. Soil continues to build up: woody plants (willows, cottonwood, alders) ~ won"t grow big but continues to modify soil, larger woody plants, shrubs, pioneer trees, spruce, hemlocks ~ forest (climax condition of succession) Took 250 years to change from rock to soil (dark loam); ph from 8. 4 to 50.
