1. COMMUNITIES AND BIOMES
Chapter 3

2. Communities
Ch. 3, Sec. 1

3. Communities
Communities = all the interacting living organisms in an area; all the different species
Limiting Factor = any biotic or abiotic factor that restricts population growth

4. Tolerance = ability of an organism to withstand fluctuations of biotic and abiotic factors

5. Succession
Succession = orderly changes & species replacement of communities in ecosystems

6. Primary Succession = colonization of barren land by communities of organisms
Pioneer Species are the 1st to arrive
Lava flow, lichen (algae & fungus), a Galapagos island

7. Pioneer species die and decompose adding nutrients back to the soil
More organisms (insects, fungus, small plants, etc.) live & die adding nutrients back to the soil
Until eventually….
Climax Community = stable & mature community that changes little

8. The Indiana Dunes are an example of primary succession

9. Areas that were once covered by glaciers are a good example of succession too

10. Secondary Succession = sequence of changes after an existing community is destroyed/damaged; a new community regrows
Mount St. Helens

11. Practice
Compare and contrast Primary Succession and Secondary Succession.
Are the starting points the same?
Are the organisms the same?

12. Biomes
Ch. 3, Sec. 2

13. What’s a Biome?
Large group of ecosystems that share the same type of climax community

14. Aquatic Biomes Approx. 75% of Earth’s surface is covered by water
Mostly salt water

15. 1. Marine Biomes = oceans, can be very shallow (surface of ocean) or very deep (bottom of ocean)
Photic Zone = portion of marine biome that is shallow enough for sunlight to penetrate
Aphotic Zone = deep water that never receives sunlight

17. Scary?

18. 2. Estuaries = mixture of freshwater & ocean water; where rivers meet the ocean
Sea grass, mangroves

19. 3. Intertidal Zone = portion of shoreline between high and low tide

20. 4. Freshwater Biomes = lakes, ponds, rivers
Lake Victoria, Amazon river

21. Terrestrial Biomes

22. Rainfall varies from biome to biome, resulting in different adaptations in species

23. 1. Tundra = cold temperatures, short growing season
Permafrost = a layer of permanently frozen soil, prevents plants from growing deep roots

24. 2. Taiga = cold, conifers (trees that produce cones)

25. 3. Desert = less than 25cm of annual rainfall
Adaptations for living in the desert
Plants = spine, waxy coating, toxins
Animals = nocturnal activity, venom, require less water
Kangaroo rat, cactus, rattlesnake

26. 4. Grassland = rich soil, trees usually by bodies of water, lots of grazing animals
Prairie, Savannah, Steppe

27. 5. Temperate Forests = trees lose their leaves each year

28. 6. Rain Forests = high biodiversity, found in tropical & temperate (moderate climate) areas
Jaguar, poison dart frog, sloth

29. Practice
How are organisms in the photic zone and aphotic zone interdependent?
(Hint: Think about what grows in the photic zone which is exposed to sunlight, what supports the base of ecological pyramids? What happens if a population of one species grows out of control?)