Major Ecosystems of the Biosphere

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Major Ecosystems of the Biosphere

• Chapter 39

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Climate Characterization

• Climate
• Average yearly temperature and precipitation of a
  region
• When terrestrial ecosystems are plotted according
  to their climate, a particular distribution
  pattern results

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Terrestrial Ecosystems

• Tundra
• Tiaga (corniferous forests)
• Temperate deciduous forest
• Grasslands ( savannahs)
• Desert
• Tropical rainforest

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1. Tundra

• Encircles the Earth just south of the ice-covered
  polar seas in the Northern Hemisphere
• Cold and dark much of the year
• winters
• extremely long, cold, and harsh
• summers
• short (68 weeks)

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1. Tundra

• Rainfall amounts to only about 20 cm per year
• Only the topmost layer of soil thaws
• permafrost beneath this layer is always frozen
• Trees are not found in the tundra
• Growing season too short and roots cannot
  penetrate permafrost

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2. Coniferous forests

• Coniferous forests are found in three locations
• Taiga
• extends around the world in the northern part of
  North America and Eurasia
• Near mountaintops
• Along the Pacific coast of North America
• Taiga forest exists south of the tundra
• Needlelike leaves of its cone-bearing trees can
  withstand the weight of heavy snow

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2. Coniferous forests

• Temperate rain forest
• Coniferous forest that runs along the west coasts
  of Canada and the United States
• Plentiful rainfall and rich soil

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3. Temperate deciduous forests

• Found south of the taiga in eastern North
  America, eastern Asia, and much of Europe
• Seasons are well defined
• Growing season ranges between 140 and 300 days

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3. Temperate deciduous forests

• Trees have broad leaves and are deciduous
• Lose their leaves in fall and grow them in spring
• Tallest trees form a canopy
• Autumn fruits, nuts, and berries provide food for
  the winter
• Leaves contribute to a rich layer of humus

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4. Temperate grasslands

• Bitterly cold winters and hot and dry summers
• Across the United States from east to west
• Temperate deciduous forest transitions into
  tall-grass prairie
• Requires more rainfall than does the short-grass
  prairie (occurs near desert)
• Large herds of bison
• Small mammals, (mice, prairie dogs, and rabbits)
  live below ground, but usually feed aboveground

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Savannas

• In regions where a cool dry season is followed by
  hot rainy season
• Largest savannas are in central and southern
  Africa
• Australia, Southeast Asia, and South America
• Characterized by large expanses of grasses with
  sparse populations of trees
• Plants have extensive and deep root systems that
  enable them to survive drought and fire

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Savannas

• African savanna
• Greatest variety and number of large herbivores
• Elephants and giraffes - tree vegetation
• Antelopes, zebras, wildebeests, water buffalo,
  and some rhinoceroses - grasses

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5. Deserts

• Northern and Southern Hemispheres
• Winds that descend in these regions lack moisture
• Annual rainfall is less than 25 cm
• Lack of cloud cover
• Nights are cold because heat escapes easily into
  atmosphere
• Most have plants highly adapted to survive long
  droughts, extreme heat, and extreme cold
• Some animals are adapted to the desert
  environment
• Nocturnal or burrowing

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6. Tropical rain forests

• South America, Africa, and the Indo-Malayan
• Temperature is always warm (20 to 25C)
• Rainfall is plentiful (minimum of 190 cm/year)
• May be the richest ecosystem
• Diversity of species is enormous
• 10 km2 area of tropical rain forest may contain
  1,500 species of flowering plants

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Tropical rain forests

• Complex structure with three levels
• Canopy
• Sunlight is filtered out
• Plants of the forest floor are tolerant of
  minimal light
• Understory
• Consists of shorter trees
• receive some light and bear epiphytes
• Plants that grow on other plants
• usually have roots of their own
• Forest floor
• Insects are abundant
• majority of species have not been identified

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Topography

• Surface features of land
• Mountains
• topographic features that affect climate and
  distribution of ecosystems
• Difference between the windward side and the
  leeward side can be quite dramatic
• Hawaiian Islands

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Topography

• Elevation affects the distribution of terrestrial
  ecosystems
• Nearby Bodies of Water
• Ocean temperature is more stable than landmasses
• Ocean water gains or loses heat more slowly than
  terrestrial environments
• Monsoon climate
• wet ocean winds blow onshore for almost half the
  year

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Fresh Water and Salt Water Are Organized into
Aquatic Ecosystems
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Fresh water flows into salt water

• Fresh water
• flows within streams and rivers
• contained in lakes and ponds
• Wetlands directly absorb storm waters and
  overflows from lakes and rivers
• protect farms, cities, and towns from the
  devastating effects of floods

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Types of lakes

• Lakes are often classified by nutrient status
• Oligotrophic lakes
• Nutrient-poor
• Have a small amount of organic matter and low
  productivity
• Eutrophic lakes
• Nutrient-rich
• Have plentiful organic matter and high
  productivity

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Marine ecosystems

• Estuary
• Partially enclosed body of water where fresh
  water and sea water meet and mix as a river
  enters the ocean
• Organisms must be able to withstand constant
  mixing of waters and rapid changes in salinity
• Nearly two-thirds of marine fishes and shellfish
  spawn and develop in the protective and rich
  environment of estuaries

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Marine ecosystems

• Intertidal zone
• Lies between the high and low tide marks
• Rocky shores and sandy shores are constantly
  bombarded by the sea as the tides roll in and out

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Oceans

• Shallow ocean waters (euphotic zone) contain a
  greater concentration of organisms than the rest
  of the sea
• Coral reefs
• Areas of biological abundance just below the
  surface in shallow, warm, tropical waters
• Most of the ocean lies within the pelagic zone
• Epipelagic zone
• lacks the inorganic nutrients of shallow waters
• Mesopelagic zone
• Bathypelagic zone
• complete darkness
• Abyssal plain
• many invertebrates survive there by feeding on
  debris floating down from the mesopelagic zone

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Oceans

• Ocean inhabitants in divisions of pelagic zone
• Epipelagic zone
• Mesopelagic zone
• Animals in the deeper waters here are carnivores
• are adapted to the absence of light
• Bathypelagic zone
• in complete darkness except for an occasional
  flash of bioluminescent light

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Ocean currents affect climates

• Climate is driven by the sun
• oceans play a major role in redistributing heat
  in the biosphere
• Air takes on the temperature of the water below
• Warm air moves from the equator to the poles
• The oceans make the winds blow

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Ocean Currents

• Because the ocean currents eventually strike
  land, they move in a circular path
• Clockwise in the Northern Hemisphere
• Counterclockwise in the Southern Hemisphere
• As the currents flow, they take warm water from
  the equator to the poles
• Gulf Stream
• brings tropical Caribbean water to the east coast
  of North America and the higher latitudes of
  western Europe