The Biosphere

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The Biosphere

• Chapter 49

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Outline

• Climate and the Biosphere
• Global Wind Circulation
• Terrestrial Communities
• Aquatic Communities
• Life Zones
• Lakes
• Estuaries
• Seashores
• Oceans

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Climate and the Biosphere

• Climate refers to prevailing weather conditions
  in a region.
• Dictated by temperature and precipitation.
• Influenced by a multitude of factors including
  tilt of the earths axis and topography.

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Effect of Solar Radiation

• Distribution of solar energy due to a spherical
  planet and the rotation and path of the Earth
  around the sun affect how the wind blows and the
  amount of rainfall various regions receive.

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Global Wind Circulation
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Rain Shadow

• As winds cross a coastal mountain range, they
  rise and release their moisture on the windward
  side of the mountain.
• Leeward side receives relatively little rain and
  is said to lie in a rain shadow.

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Formation of a Rain Shadow
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Terrestrial Communities

• Biome has a particular mix of plants and animals
  adapted to living under certain environmental
  conditions.
• Often delineated by climate.
• Temperature and precipitation varies according to
  latitude and altitude.

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Biome Distribution
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Climate and Biomes
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Tundra

• Arctic tundra encircles Earth just south of
  ice-covered polar seas in Northern Hemisphere.
• Covers 20 of Earths land surface.
• Trees are not found in the tundra because growing
  season is too short.
• Roots cannot penetrate permafrost.

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Tundra
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Coniferous Forests

• Taiga typifies coniferous forest with
  cone-bearing trees.
• Trees well adapted to cold.
• Leaves and bark have thick covering.
• Needle-like leaves can withstand weight of heavy
  snowfall.
• Temperate Rainforest (Old-Growth Forests) of
  Pacific Northwest.
• Evergreen forest.

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Temperate Deciduous Forests

• Found south of taiga in eastern North America,
  eastern Asia, and much of Europe.
• Well defined season with long growing seasons.
• Tallest trees form a canopy.
• Ground-life is plentiful.

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Temperate Deciduous Forest
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Tropical Forests

• Found in equatorial regions.
• Plentiful rainfall.
• Most animals live in trees.
• Abundant insect life.
• Epiphytes grow in many areas.
• Soils are nutrient-poor.
• Rapid recycling of nutrients.
• Swidden agriculture successful but destructive.

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Shrublands

• Tend to occur along coasts that have dry summers
  and receive most of their rainfall in the winter.
• Shrubs adapted to withstand arid conditions.
• Dense shrubland in California known as chaparral.

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Grasslands

• Grasslands occur where annual rainfall is greater
  than 25 cm, but generally insufficient to support
  trees.
• Grasses well adapted to changing environment.
• Temperate Grasslands
• Savannas

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Temperate Grassland
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Savanna
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Deserts

• Usually found at latitudes of about 30o in both
  north and south hemispheres.
• Descending winds lack moisture.
• Annual rainfall less than 25 cm.
• Large temperature differential between day and
  night.

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Deserts
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Aquatic Communities

• Lakes
• Bodies of water classified by their nutrient
  status.
• Oligotrophic - Nutrient-poor.
• Eutrophic - Nutrient-rich.
• Lake Stratification
• In temperate zones, deep lakes are stratified in
  the summer and winter.

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Life Zones

• Plankton are important community components in
  fresh water and salt water.
• Phytoplankton - Algae
• Zooplankton - Animals
• Life Zones
• Littoral zone - Closest to shore.
• Limnetic zone - Sunlit areas.
• Profundal zone - Below light penetration.
• Benthic zone - Soil-Water interface.

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Zones of a Lake
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Coastal Communities

• Estuaries
• Partially enclosed bodies of water where fresh
  water and seawater meet and mix.
• Organisms must be able to adapt to changing
  salinity.
• Estimated over half of all marine fishes develop
  in protective environment of estuaries.

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Estuary Structure and Function
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Seashores

• Littoral zone lies between high and low water
  marks.
• Littoral zone of rocky beach divided into
  subzones.
• Organisms cannot attach to shifting, unstable
  sands therefore nearly all permanent residents
  dwell underground.

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Seacoasts
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Oceans

• Major ocean currents move heat from the equator
  to cooler parts of the biosphere.
• Gulf Stream warms east coast of North America and
  parts of Europe.
• El Nino Southern Oscillation
• Cold upwelling off west coast of South America
  subsides.

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Ocean Currents
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Oceans

• Pelagic Division
• Neritic Province
• High concentration of organisms due to sunlight
  penetration and supply of inorganic nutrients.
• Coral Reefs
• Oceanic Province
• Lacks inorganic nutrients and thus does not have
  high concentration of phytoplankton.

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Oceans

• Benthic Division
• Includes organisms that live on or in the
• Continental Shelf (sublittoral zone)
• Continental Slope (bathyal zone)
• Abyssal Plain (Abyssal zone)
• Interrupted by hydrothermal vents.
• Organisms are dependent on debris floating down
  from above.

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Review

• Climate and the Biosphere
• Global Wind Circulation
• Terrestrial Communities
• Aquatic Communities
• Life Zones
• Lakes
• Estuaries
• Seashores
• Oceans

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