Understanding Ecosystems: Community Balance and Biome Diversity

1. Chapter 3 Communities and Biomes

2. How do communities keep a balance-(homeostasis)? • Ecosystems changeconstantly- • slow and fast slow-growing of trees fast-fire and floods • As the ecosystem changes, so do the organisms in it The environment determines the organism

3. Limiting factors any biotic or abiotic factor that restricts the existence, number, reproduction, and distribution of organisms -affects an organisms ability to survive in it’s environment Organisms can handle change if it’s not too severe

4. tolerance the ability of an organism to handle fluctuations in biotic or abiotic environmental factors. Ex. Fish can tolerate some temperature and O2 changes in H2O

5. Communities always change over time. It occurs so slow that you do not notice. Succession- orderly, natural changes and species replacement that take place in communities of an ecosystem.

6. 2 types of succession: • 1. Primary succession • 2. Secondary succession

7. Primary succession- the colonization of new sites by communities of organisms • Ex. Plants grow on bare rock and plants growing after lava flow. Pioneer species- 1st inhabitants/species in an area (usually lichens) Climax community- stable, mature community that undergoes little or no change (no more succession) in the species.

8. Secondary succession- • the sequence of community changes that take place after a community is disrupted by natural disaster or human activities • ex. Hurricanes, flood, fire, plowing, etc.

9. Aquatic Biome (Covers 75% of the Earth’s surface) Freshwater-lakes, rivers, streams, ponds Marine – saltwater The ocean has the largest amount of living material than any other biome. Most are tiny, microscopic organisms

10. Zones of the ocean: 1. Photic zone- portion of the marine biome that is shallow enough for sunlight to penetrate. Plankton- organisms found in the water of the photic zone; ex. Tiny, shrimp-like creatures, jellyfish, worms, juvenile crabs, snails, fish. • 2. Aphotic zone- • deep water that never receives sunlight; pure darkness, cold, pressure. Organisms that live in this zone sometimes come to the photic zone to feed on the plankton; • ex. Fish → eat shrimp → eat plankton

11. Estuary- a coastal body, partially surrounded by land, where fresh water and salt water mix, where the river meets the ocean. The amount of salt water in this area depends on how much fresh water enters and the tides bringing in salt water. • Intertidal zone- the portion of the shorelines that lies between the high and low tide lines.

12. Biome- a large group of ecosystems that share the same type climax community.

13. Terrestrial Biomes- Land What environmental changes do you see as you go toward the north pole? Temperature, terrain, precipitation, sunlight How do the communities (organisms) vary? Plants and animals change with the biomes

14. The type of climax community in an area depends on two abiotic factors: -1. precipitation (rain, snow, etc.) -2. temperature

15. Main Terrestrial Biomes: 1. Ice- close to poles, 90 degrees north and south, only bacteria can survive in some of these areas.

16. 2. Tundra (Artic zone)- ~60-90 degrees north – cold – a treeless land with long summer days and short periods of winter sunlight. Contains permafrost- permanently frozen ground underneath topsoil.

17. 3. Taiga- Northern coniferous forest, ~ 60 degrees north, swampy, cold-but not extreme or excessive.

18. 4. Temperate forests- mainly 30 degrees north and south – includes much of the U.S. forest – rainfall of 75-150 cm/yr -forests dominated by broadleaf hardwood trees that lose their leaves annually (deciduous)

19. 5. Grasslands (prairies)- wide range 50 degrees north and south average- -communities covered with grasses and small plants - averages 25-75 cm/yr of rainfall.

20. 6. Desert- ~0-30 degrees- -an arid region with sparse plant life -rainfall usually less than 12 cm/yr (25 cm/yr).

21. 7. Tropical rain forests- ~ 0degrees – found near the equator • warm temperatures with minimal fluctuation -wet weather, lush plant growth, lot of life. -has layered forest

22. Layers of the rain forest • Emergent layer-sticks out beyond the main tree layers • Canopy layer- top layer that receives a lot of sunlight • Where most animals are found • Understory layer- layer beneath canopy • Ground layer- floor of forest • Not many plants and animals due to lack of sun reaching it (dark) • Most dead material is broken down before it reaches here