Transcript Understanding Our Environment

Biomes
Outline
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Tundra
Taiga
Temperate Deciduous Forest
Grassland
Desert
Mountain and Coastal Forest
Tropical Rain Forest
Tundra
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Primarily above the arctic circle.
Appears treeless.
Precipitation averages < 25 cm annually.
 Permafrost holds water at or near the
surface.
 Short growing season of 2-3 months.
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 High temperatures range to about 27 C.
 Very fragile.
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Taiga
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Northern Conifer (Boreal) Forest
Adjacent and south of arctic tundra.
Dominated by Spruce, Fir, and Pine.
Few Annuals.
Temperate Range -50oC to 30oC.
Annual precipitation ranges from 25-100 cm.
 Most occurs in the summer.
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Temperate Deciduous Forest
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Composed of mostly broad-leaved species
that shed their leaves during the fall, and
remain dormant during short winter days.
Most occur in large continental masses in
Northern Hemisphere.
Temperatures range from 4oC to 20oC.
Annual precipitation ranges from 50-165 cm.
 Mostly occurs in summer
During summer, solid canopy keeps direct
sunlight from reaching the forest floor.
Grassland
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Found in interior of continental masses.
Annual precipitation ranges from 25-100 cm.
Temperatures range from -45oC to 45oC.
North American grasslands (prairies) grew on
fertile soils supporting large herds of
migratory grazing buffalo.
 Mediterranean climate receives most
precipitation in the winter, thus grasses do
not grow as tall as those of Midwestern
prairies.
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Desert
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Many of the world’s major deserts are
located at 30o N and 30o S latitude.
Most receive < 12.5 cm annual precipitation.
Low humidity.
Wide daily temperature fluctuations.
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 15 C - 35 C on a hot summer day.
Some plants exhibit CAM photosynthesis.
Other plant adaptations include thick cuticles,
water-storage tissues in stems and leaves,
and thick leaves and / or reduced in size.
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Mountain and Coastal Forest
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Coniferous forests occupy vast areas of the
Pacific Northwest as well as portions of the
Rocky Mountains and the Sierra Nevada.
Conspicuous altitudinal zonation of species.
Relatively dry summers.
 Frequent forest fire regime.
- Fire-adaptations.
 Bark
 Cones
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Tropical Rain Forest
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Annual precipitation ranges from 200-400 cm.
Temperatures range between 25oC and 35oC.
No dry season.
Humidity usually > 80%.
Dominated by broad-leaved evergreen trees.
Shallow root systems.
Dense multi-layered canopy.
Poor soils
 Nutrients either uptaken by plants or
leached by heavy rainfall.
Review
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Tundra
Taiga
Temperate Deciduous Forest
Grassland
Desert
Mountain and Coastal Forest
Tropical Rain Forest
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