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Ecosystems and Communities

Ecosystems and Communities. Chapter 4 & 5 Notes. Every organism affects its environment, and in turn is affected by its environment.  Ecosystems are affected by two kinds of factors abiotic factors, or non-living factors: examples include temperature, soil, precipitation, etc.

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Ecosystems and Communities

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  1. Ecosystems and Communities Chapter 4 & 5 Notes

  2. Every organism affects its environment, and in turn is affected by its environment.  Ecosystems are affected by two kinds of factors • abiotic factors, or non-living factors: examples include temperature, soil, precipitation, etc. • biotic factors, or living factors: examples include organisms of the same species and organisms of different species

  3. Biotic or Abiotic? • Predators • Hot weather • Acid rain • Wood from trees • Your parents • The river flow • The leeches found in the river

  4. Weather: day-to-day conditions of the Earth’s atmosphere at a particular time and place Temperature Wind Precipitation Humidity Specific weather patterns Weather for Sugar Land, TX Sunday Sept. 16, 2007 The Role of Climate

  5. The Role of Climate • Climate: it is the average conditions in a region over several decades; affects the soil, and in turn the vegetation, and in turn other organisms in an area. It is described by: • temperature • precipitation

  6. The Role of Climate • Temperature is determined by latitude/ angle of sunlight.

  7. Polar: 90-66.5º N or S (within the Arctic and Antarctic circles) Temperate: from the lines of Tropic of Cancer and Capricorn to 66.5 º N or S, respectively Tropical: between the Tropic of Cancer and Tropic of Capricorn The Role of Climate • Polar (blue) • Temperate (green) • Tropical (red)

  8. Other determinates of weather and climate: • Coastal or central to the continent? • Wind and ocean currents are driven by unequal heating of land and water

  9. Other determinates of weather and climate: • Upwelling: flow of denser cold water from the poles parallel to the ocean bottom and eventually rising in warmer regions Diagram illustrating the principle of equatorial upwelling. Winds along the equator (dotted line) create currents, which are then diverted north and south by the Coriolis force. The cold, deep waters from below rise to the surface to replace these diverted waters, causing upwelling. http://earthguide.ucsd.edu/virtualmuseum/climatechange1/11_2.shtml

  10. Greenhouse Effect: the natural situation in which heat is retained by the greenhouse gases (CO2, methane, water vapor, etc.) is called the greenhouse effect. If these gases were not present, the Earth would be 30º C cooler and unlivable

  11. Biomes • -a collection of ecosystems with the same climate and dominant communities; 2 main areas of biomes • Aquatic- in water • Terrestrial- on land

  12. Aquatic • Photic zone- where light penetrates (shallow water) • Aphotic zone- no light (deep water) • Estuary- where fresh and salt water meet (end of a river) • Tidal zone- beach front Tidal Zone Photic Zone Aphotic Zone

  13. Photic Zone Great Barrier Reef, Australia

  14. Aphotic Zone • Photo credit: Edith Widder/HBOI

  15. Estuary Louisiana swampy areas

  16. Tidal Zone • From low tide to high tide

  17. Tropical Rainforest Costa Rica

  18. Tropical Dry Forest Fiji

  19. Tropical Savanna African Savanna

  20. Desert Sonoran Desert, Arizona

  21. Temperate Grasslands

  22. Temperate Woodland and Shrubland

  23. Temperate Forest Kauri Forest in North Island of New Zealand

  24. Northwestern Coniferous Forest Canadian Rockies

  25. Taiga/ Boreal Forest Alaska

  26. Tundra

  27. Community Interactions • Habitat- place an organism lives • Niche- the role of an organism in an ecosystem, every organism has a specified role it fulfills • Competition- competing for resources, shelter, space, mates, etc. • Interspecific competition: between members of different species • Intraspecific competition: between members of the same species

  28. Predation- an organism hunts and feeds on another organism, ex: lion eats a zebra

  29. Community Interactions • Symbiosis- the relationship of organisms from DIFFERENT species living closely + + + - + 0

  30. Community Interactions • Mutualism- both species benefit from the relationship (ant live on an acacia tree, ant protects tree from harmful plants, tree gives ant a home) Clownfish live within sea anemones, which normally sting other fish. The fish gets protection, and the anemone benefits because the clownfish keep it clean of bacteria.

  31. Community Interactions • Parasitism- one organism gains benefits at the other’s expense (fleas or ticks on a dog; flea gets a home, sucks the dog’s blood and is bothered by it) Leech sucks the blood of a human

  32. Community Interactions • Commensalism- one species benefits and the other is not hurt nor helped (moss growing on trees) Epiphytes are plants that grow on other plants without harming them. They never set root in the ground!

  33. Factors Affecting Populations • Three things affect population size: • # of births • # of deaths • # of individuals immigrating (entering) or emigrating (leaving)

  34. Exponential Growth- if a population has abundant space and food, no disease or predators; it will grow at an exponential rate. It is a J-shaped curve resembling y = ax2 + b Types of Growth

  35. Logistic Growth- population growth slows then stops (stays stable) after a period of exponential growth once resources become less available. The number at which the environment can support this population is known as the carrying capacity. Types of Growth

  36. Limiting factors • factor that causes a population to decrease in size • Two types…

  37. Limiting Factors • Density dependent- relies on how many organisms in a define space are in that population; can include things like competition, predation, parasitism, and disease • Notice the pattern of population size with predator/prey relationship of hares and lynxes

  38. Limiting Factors • Density independent- affect all populations in similar ways, regardless of the population size. • Unusual weather • natural disasters • seasonal cycles • certain human activities

  39. Ecological Succession • After such disasters, a community can start anew by a process called ecological succession (series of predictable changes that occurs in a community over time); there are two types

  40. Succession • Primary succession- a community start where no soil is present (after a volcanic eruption/ glacier retreats)

  41. Succession • Secondary succession- a community starts where soil is present (after a fire, disease, natural disaster)

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