Ecology: Biome Concepts

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Ecology: Biome Concepts
2014-10-18 16:33:56
BIO 181 Exam II
Biomical stuff
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  1. Biomes
    • Major vegetation zones of the Earth with characteristic vegetation and animals
    • Characteristic life forms in each biome with similar body plan but not related taxonomically
    • Convergent evolution occurs in biomes (e.g. cactus-like plans in deserts; cacti in North America, euphorbs in Africa)
  2. Major Biome Types
    • Tundra
    • Taiga (northern coniferous forest)
    • Grasslands
    • Temperate forests
    • Tropical forests
    • Desert
  3. Biome type is determined by the interactions of
    • Climate - overriding cause
    • Geography - can modify climate
    • Soils - related to geography, geology, and climate
  4. Climate
    average weather over the course of several years
  5. Major Factors of Climate
    • temperature
    • precipitation
  6. Major factors of climate are affected by
    • latitude
    • positions of continents
    • geophysical features such as mountains and plains
  7. Causes of Climate
    • Directness of  Insolation
    • Tilt of Earth at 23° on Axis
    • Prevailing Winds
    • Ocean currents
    • Geography
  8. Directness of Insolation (Climate)
    • how direct incoming sunlight is at a point on Earth
    • due to the fact that Earth is a sphere
    • Equatorial regions - more direct, warmer
    • Polar regions - more indirect, cooler
  9. Tilt of Earth at 23 degrees on axis
    • Causes seasonality
    • Less seasonality at equator - effect of tilt less pronounced
    • More seasonality toward poles - effect of tilt more pronounced
    • Northern Hemisphere tilts toward the sun in summer - insolation more direct
    • Northern Hemisphere tilts away from the sun in winter - insolation less direct
    • Southern Hemisphere - vice versa
  10. Prevailing Winds
    • Due to uneven heating of Earth's surface and rotation of Earth
    • Descending air = adiabatic warming, less rainfall
    • Rising air = adiabatic cooling, more rainfall
  11. Global Atmospheric Circulation Patterns
    • North pole to 60° N - Descending
    • 60°N to 30°N - Rising
    • 30°N to Equator - Descending
    • Equator to 30°S - Rising
    • 30°S to 60°S - Rising
    • 60°S to South Pole - Descending
  12. Why are most deserts at 30° North or South and tropical rainforests are near or at the equator?
    • Warm air rises in equatorial regions, which absorbs water readily
    • Adiabatic cooling of the air mass occurs as it rises; cooler air holds less water, causing rain in the tropics
    • Rain results in dry air as the air mass descends at 30° North or South
    • Furthermore, adiabatic warming of the air mass warms the air and holds more water
  13. Ocean Currents
    • Water retains heat well
    • circulates in huge circular gyres
    • carry heat from equator to poles
    • can moderate climate near costs
    • east coasts - warmer (equator to pole)
    • west coasts - cooler (pole to equator)
  14. Continental Climates
    • away from moderation by oceans
    • have colder winters 
    • e.g. Siberia and Alberta are on the same latitude as London but have much colder winters
  15. How do mountains affect climate?
    • Localized climates due to great differences elevations over short distances
    • Can affect rainfall
    • Rain occurs on windward side of the mountain
    • Moist air is forced upward, with the adiabatic cooling causing rain
    • Air descends on leeward side of mountain
    • Adiabatic warming occurs, creating a dry climate - effect known as rain shadow