1. CHAPTER 3: COMMUNITIES + BIOMES 3-1: COMMUNITIES P.65-69

2. Life in a Community Types of things found in your lawn: –Weeds –Insects –Earthworms –Grubs –Soil –Fungi –Bacteria

3. Life in a Community How do all these things survive? –The various combination of biotic + abiotic factors

4. Limiting Factors Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms Such as: –Availability of food + water –Predators –Temperature

5. Common Limiting Factors Sunlight Climate Temperature Water Nutrients/Food Fire Soil Chemistry Space Other Organisms

6. Limiting Factors indirectFactors that limit one population in a community may also have an indirect effect on another population Example: –Lack of water Affects growth of grass Affects # seeds produced Affects # mice Affects # hawks

7. Ranges of Tolerance Tolerance –The ability of an organism to withstand fluctuations in biotic + abiotic environmental factors (“EXTREMES”) –Represented by a GRAPH

9. Succession: Changes over Time SuccessionSuccession –The orderly, natural changes and species replacements that take place in the communities of an ecosystem –Occurs in STAGES –Difficult to observe because it can take decades or centuries for communities to succeed

10. Primary Succession The colonization of barren land by communities of organisms –Takes place on land where there are no LIVING ORGANISMS –Example: Volcano

11. Primary Succession Pioneer speciesPioneer species –First species to appear on new, barren land –Example: Lichen – group of small organisms

12. Primary Succession – the process… Pioneer species dies…. Provides 1 st stage of soil…. New soil develops…… Small weedy plants develop… New organisms move in… Area grows in size….

13. Primary Succession After some time, primary succession slows down and becomes stable Climax community –Mature, stable community with little or no change –Change is dynamic – balances out –May last for hundreds of years

14. Primary Succession Stages

15. Secondary Succession Sequence of changes that takes place after an existing community is severely disrupted in some way –i.e. A natural disaster Community of organisms inhabiting an area gradually changes Occurs in areas that previously contained LIFE + land still contains soil

16. Secondary Succession May take less time to reach climax community Example: –Yellowstone National Park (1988)

17. Secondary Succession Stages