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Ch. 5, Section 3: How Ecosystems Change Standards: SEV1a, b, d, e, SEV5c.

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Presentation on theme: "Ch. 5, Section 3: How Ecosystems Change Standards: SEV1a, b, d, e, SEV5c."— Presentation transcript:

1 Ch. 5, Section 3: How Ecosystems Change Standards: SEV1a, b, d, e, SEV5c

2  A gradual process of change and replacement of some or all of the species in a community.  Can take 100’s or 1000’s of years.  Ends in a climax community

3  Final, stable community.  Generally remains the same if undisturbed  Type of climax community will vary depending on ecosystem  Climax community for a desert is different from tropical rainforest  Both primary & secondary succession end with a climax community.

4 1. PRIMARY  occurs on a surface where no ecosystem existed before  Ex: rocks, sand dune, new island 2. SECONDARY  Occurs on a surface where an ecosystem has previously existed.  Ex: after fire, volcano, flood, abandoned farm

5 Typical primary succession of forest:  Rock is physically & chemically weathered & broken down to make soil.  Physical- frost wedging- frozen water expands & creates cracks  Chemical- pioneer species like lichens & moss can secrete acids to dissolve rock.  Thin soil can support grasses  As grasses die & decompose they contribute to soil layer and soil gets thicker.  As soil thickens it can support larger plant life like shrubs  First trees that grow are usually sun loving trees like pines  As pines grow tall they shade their saplings, saplings can’t get sun and die off.  Shade loving trees like deciduous trees (oak, hickory) grow under pines, eventually outgrowing and replacing pines.

6  Soil is already established so it doesn’t have to be created.  Takes less time than primary  More common than primary succession  Pioneer species- grasses, weeds  Shrubs  Pine trees  Deciduous trees  3 examples:  After a fire  After a field is abandoned  Pond becomes a forest

7  Some ecosystems rely on natural fires to maintain the ecosystem.  Ex: grasslands, chaparral  Fires are actually beneficial:  Jack pine trees need intense heat of fire to release seeds  Animals eat new, soft plants that sprout right after fire when soil is nutritious  Minor forest fires burn accumulation of brush & deadwood that would otherwise contribute to major fires.


9  Farmers field becomes a forest.  Pioneer species of grasses establish quickly due to rich soil.

10  Ponds can fill in and become a forest if not maintained.  Pond fills in with dead leaves, debris, eroded sediment.  Makes pond more shallow.  Sunlight helps plants grow in shallow pond  Eventually fills in completely with sediment & secondary succession continues.

11  What is the difference between primary and secondary succession?  What role does a pioneer species play during the process of succession?  Why would putting out forest fires be damaging in the long run?  What role do lichens play in primary succession?  How are lichens similar to the pioneer species that colonize abandoned farm areas? How are they different?

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