COMMUNITIES AND BIOMES Chapter 3

Communities Ch. 3, Sec. 1

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

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

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

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

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

The Indiana Dunes are an example of primary succession

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

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

Biomes Ch. 3, Sec. 2

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

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

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

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

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

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

Terrestrial Biomes

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

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

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

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

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

5. Temperate Forests = trees lose their leaves each year

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

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