Biomes

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Biomes
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A biome is large region of the earth that is
broadly characterized by
specific climate (temperature precipitation)
occupation of a large geographic area
similar plant communities
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Temperature Precipitation influence terrestrial
biomes
Tropical rainforest
Temperate forest
Increasing precipitation
Coniferous forest
Grassland
Desert
Cold desert
Increasing temperature
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Biomes and latitude
Why are rainforests always found near the equator
and deserts near 30o latitude?..
because of rotating columns of air in the
atmosphere called Hadley cells.
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Biomes of Africa
The Hadley cell over northern Africa rotates
counterclockwise.
30o
desert
As the warm air rises, it cools, condenses and
loses its moisture as rain in the tropics.
0o
rainforest
The dry air then descends and pulls moisture from
the surface of the desert.
desert
30o
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World distribution of biomes
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Biomes and altitude
This rain shadow effect is the reason for the
Sonoran Desert in the American Southwest.
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Desert
Characterized by low precipitation and high
average temperature
Usually found just beyond the tropics (30o north
or south)
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Tropical rainforest
Characterized by abundant precipitation and high
average temperature
Usually found between 0o and 30o north or south
the Tropics
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Grassland
Characterized by infrequent seasonal
precipitation and relatively high average
temperature
The dominant plants (grasses) are not succeeded
by trees because of natural fires (due to
lightning) and grazing by large herbivores
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Temperate forest
Characterized by plentiful moisture and seasonal
temperature fluctuations
Most trees are deciduous, shedding their leaves
in response less available moisture in winter
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Coniferous forest
Most trees are coniferous, or cone-bearing, and
leaves are evergreen (needles) that are adapted
to retaining moisture when water supplies are
frozen and unavailable
Found in Northern latitudes, but south of tundra
polar regions
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Aquatic systems
Many aquatic ecosystems (ponds, lakes, streams,
rivers, etc.) are found within terrestrial
biomes, and are subject to the same physical
characteristics as terrestrial components, except
the surrounding medium is water, not air.
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Physical factors that affect living organisms in
the water
 1. Light
2. Pressure
3. Oxygen levels
4. Temperature
5. Salinity
6. Changing water levels
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Oceans
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Ocean zonation
90
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1
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End