1. Symbiosis Clip

2. Ecological Succession Ecological Succession: Series of predictable changes in a community over time. Ecosystems are constantly changing because environmental conditions change. Some species die out and others move in. –Change may be caused by a disturbance (natural or human caused) Flood, land slide, volcano, fire, insects, disease, etc. –Or conditions in one stage of succession may benefit another set of species. Shade, change in moisture or nutrients, soil, etc.

3. Primary Succession Succession that occurs where no soil exists. Pioneer species are the first species to colonize and area Lichens (break down rock into soil)

4. Melting Glacier

5. Secondary Succession Secondary Succession * Still some remaining plant matter and soil When a disturbance affects an existing ecosystem (wind storm, flood, fire, insects) Then the community tends to interact to restore the ecosystem and works faster than primary succession Wildfire Wind Logging

6. Secondary Succession Primary forest with shade intolerant trees: Pines, Larch, Douglas fir. Shade intolerant trees create shaded forest floor. Conditions favor growth of shade tolerant species: Grand fir, Hemlock, Red cedar. Shade tolerant species cont. to create conditions for shade tolerant trees until a disturbance occurs.

8. Climax Communities Ecological community in the final stage of succession, in which the species composition remains relatively stable (and resembles the original community) until a disturbance such as fire occurs. Desert Coral Reef Forest