What Controls the Distribution of Plants and Animals on Earth

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What Controls the Distribution of Plants and
Animals on Earth?

• The interactions of organisms with their
  environment
• The interactions of organisms with other organisms

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Environments

• Aquatic
• Terrestrial
• Both impacted by weather and climate
• Major controlling factors are temperature and
  precipitation

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Global and Regional Climate

• Climate average weather of a place
• Average temperatures
• Average number of severe weather events
• Weather current conditions
• Temperature
• Cloud cover
• Precipitation (rain or snowfall)

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Temperature

• Temperature is a depends on two factors
• Location on the globe (i.e. warmer at the equator
  than at the poles)
• The local environment

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Global Temperature Patterns

• Broadly, average temperature for a locale is
  determined by the amount of solar irradiance it
  receives amount of light energy per unit area
• Large amounts of solar irradiance have higher
  average temperatures

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Global Temperature Patterns

• The position of the axis in relation to the sun
  determines how much solar irradiation hits the
  Earth
• Poles the extremes of Earths axis
• Equator circle around Earth equidistant to both
  poles

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Global Temperature Patterns

• Since the axis has a 23.5 tilt, the northern
  hemisphere and southern hemisphere have opposite
  seasons
• Summer in northern hemisphere tilted toward sun
• Winter in southern hemisphere tilted away from
  sun

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Global Temperature Patterns

• The axis tilt also causes the position of the
  sunrise to move
• South to north when winter turns to summer
• Solstice sun reaches its maximum and minimum
  elevation in the sky
• Summer solstice sun at northernmost point, North
  pole is tilted closest to the sun
• Winter solstice sun at southernmost point

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Global Temperature Patterns

• The closer region is to pole, the greater the
  variance in solstice daylight length
• Summer solstice is when there is the highest
  amount of solar irradiation, but it is not the
  warmest day of the year
• The warmest day is about one month after solstice
  the energy from the sun is stored as heat and
  slowly released

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Local Factors That Influence Temperature

• Besides solar irradiance, three other factors
  affect a locations temperature
• Altitude
• Proximity to water
• Topography and vegetation

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Local Factors That Influence Temperature

• 1. Altitude
• Temperatures decrease as altitude increases
• Sunlight heats the earth, not the air
• The heat is radiated into the air from the earth
• Air is heated from the ground up

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Local Factors That Influence Temperature

• 2. Proximity of a large body of water
• Water has a high heat absorption capability
• Bodies of water resist fast changes in
  temperature
• The air over water is cooler in summer and warmer
  in winter than the adjacent land mass

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Local Factors That Influence Temperature

• 3. Land surface and vegetation factors
• Light can be absorbed or reflected
• Surfaces that reflect light are cooler and
  therefore the area around this surface will have
  a lower temperature
• Snow reflects more light than forests
• Urban areas with asphalt absorb more light than
  rural areas

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Distribution of Precipitation on Earths Surface

• Solar energy is a primary factor in precipitation
  patterns on Earth
• Precipitation occurs when condensation exceeds
  evaporation in the water vapor within the air
• Temperature drives evaporation rate
• Temperature and wind patterns drive precipitation

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Local Precipitation Patterns

• Local precipitation patterns are highly dependent
  on how close the area is to a large body of water
• Communities near the Great Lakes get lake effect
  precipitation
• How much precipitation areas get depends on where
  they are in relation to the lakes

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Local Precipitation Patterns

• Rain shadow effect in precipitation pattern
  caused by mountains
• Windward side cooler air get more
  precipitation
• Other side drier
• Great Basin of North America is a desert from the
  rain shadow of the Sierra Nevada mountains

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Terrestrial Biomes

• Climate is the most important factor in the
  physical appearance of a geographic regions
  vegetation
• By natural selection, plants and animals adapt to
  specific climatic conditions

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Terrestrial Biomes

• Four basic land biome categories (primary
  vegetation types) exist
• Each biome category may contain several biome
  types
• Forest
• Grassland
• Desert
• Tundra

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low
tundra
coniferous forest (taiga)
Temperature
temperatedeciduous forest
cool desert
cool grassland
temperaterain forest
warm desert
warm grassland
savanna
high
tropicaldeciduous forest
tropicalrain forest
high
Rainfall
low
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Forests and Shurblands

• Forests are communities dominated by trees and
  other woody plants
• Occupy about 1/3 of Earths surface
• Account for 70 of Earths biomass

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Forests and Shurblands

• There are three forest categories, based on
  distance from equator
• Tropical forest (at or near equator)
• Temperate forest (23 to 50 north and south of
  equator)
• Boreal forest (close to the polls)
• The biome chaparral is dominated by wood plants,
  but is not a forest

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Forests and Shrublands

• 1. Tropical forests
• Once found throughout Central and South America,
  central Africa, India, southeast Asia, and
  Indonesia
• High biodiversity
• High solar energy levels
• Supports many organisms
• Many organisms live in treetops

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Forests and Shrublands

• Tropical forest also characterized by
• Warm temperatures
• Abundant water
• High energy levels
• Rapid decomposition
• Breakdown of waste and dead organisms

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Forests and Shrublands

• Vegetation quickly absorbs the nutrients soil
  isnt nutrient rich
• This decomposition and reusing of nutrients
  supports the forest
• Human activity, especially slashing and burning
  of he forests to allow for human agricultural
  pursuit, has significant effect on tropical rain
  forests

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Forests and Shrublands

• 2. Temperate forests
• Mostly in eastern North America some left in
  central Europe and eastern China
• Seasonal changes
• Wet and dry / warm and cold
• Abundant water, but less in winter
• Large trees broad leaves

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Forests and Shrublands

• Deciduous leaves fall off
• Early spring no leaves on trees allows sunlight
  to get to the forest floor
• Triggers a blooming of wildflowers that flower,
  fruit, and produce seeds quickly before sunlight
  becomes scarce again

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Forests and Shrublands

• The soil in temperate forests is rich in
  nutrients
• Much of these areas in the eastern U.S. have gone
  from forest, to farmland, back to (second growth)
  forest
• Second growth forest now threatened again by
  human development

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Forests and Shrublands

• 3. Boreal forests
• Largest biome on Earth in vast areas of North
  America, northern Asia and Europe, and
  high-altitude western U.S.
• Long, cold, snowy winters
• Coniferous (seed cone producing) trees dominate

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Forests and Shrublands

• Boreal forests have short growing season for
  plants
• Most trees are evergreens can photosynthesize
  as soon as spring begins
• Most wild landscapes on Earth not heavily
  populated by humans, which adds to biodiversity

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Forests and Shrublands

• Chaparral
• Not a forest, but has mainly woody plants and
  spiny evergreen shrubs
• Found in southern California areas surrounding
  the Mediterranean Sea and patches in southern
  California, South Africa, and Australia
• Long, dry summers

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Forests and Shrublands

• Frequent fires many species who need fire for
  seed germination to occur
• Perennials have extensive root systems and can
  quickly regrow after above ground portion of
  plant is damaged
• If fires are suppressed chaparral will turn
  into temperate forest

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Grasslands

• Nonwoody grasses dominate grassland regions
• Few shrubs or trees precipitation amounts too
  low to support them
• Two categories
• Topical
• Temperate

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Grasslands

• 1. Tropical
• Tropical grasslands are called savannas
• Cover about half of Africa large areas of India,
  South America, and Australia
• Only scattered, individual trees
• Support huge herds of grass-eating mammals and
  their predators

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Grasslands

• 2. Temperate
• 2 types of temperate grasslands tallgrass
  prairies, shortgrass steppes
• Found in central North America, central Asia,
  parts of Australia, and southern South America
• Vegetation height correlated to rain amount

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Desert

• Deserts are areas with less than 20 inches of
  rain per year
• Close to the equator very dry air
• Very hot during day and can be very cold at night

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Desert

• Deserts are areas with less than 20 inches of
  rain per year
• Deserts are found throughout the globe, but the
  worlds greatest deserts include
• Sahara in northern Africa
• Gobi of central Asia
• Deserts of the Middle East, central Australia,
  and southwestern U.S.

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Desert

• Deserts tend to be close to 30 north or south of
  equator
• Areas where air masses wrung of water in
  rain-forest regions fall back to Earths surface
  as hot and dry wind

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Desert

• Plants and animals adapted to conserve water
• Plants with spines and poisons for protection
• Plants have photosynthetic adaptations
• Annual herbs grow well produce seeds that can
  survive until next growing season

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Tundra

• Temperatures are coldest in the tundra biome
• Areas closest to Earths poles and at high
  altitudes
• Plant growth can be sustained for only 50 to 60
  days a year

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Tundra

• Tundra tends to be underlaid by permafrost, icy
  blocks of gravel and finer soil material
• Low growing, ground-hugging plants
• Many types of grazing animals
• Caribou, musk oxen etc.
• And predators such as wolves

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Tundra

• Animal adaptations to tundra environment include
• Extra fur or feathers
• Hibernation
• Storing extra fat
• Migration

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Tundra

• While the tundra is inhospitable to humans, human
  activity is affecting it
• Large oil deposit reserves of Arctic tundra are
  access to reach without disturbing environment
• World-wide consumption of fossil fuels might be
  raising temperatures to point where tundra will
  become boreal forest

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Aquatic Biomes

• Most of the human population lives near a major
  body of water and thus are influenced by and have
  an influence on these aquatic systems
• Aquatic biomes are in two categories
• Freshwater
• Saltwater

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Freshwater

• Freshwater is characterized by low salt
  concentration (less than 1 of total volume)
• There are 3 types of freshwater biomes
• Lakes and ponds
• Rivers and streams
• Wetlands

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Lakes and Ponds

• Lakes and ponds inland bodies of water (ponds
  are usually smaller)
• Different zones for lakes and ponds
• Surface and shore warmer, brighter, and lots of
  life
• Deep water dark, cold, low oxygen, and home
  mainly to decomposers

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Lakes and Ponds

• Biological productivity of lakes is increased by
  seasonal turnovers
• Air temperature change and wind cause water to
  mix, redistribute nutrients from lake bottom, and
  bring fresh oxygen to the bottom

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Lakes and Ponds

• Nutrients from land often enter lakes and pond
  causing increased growth of algae
• If too many nutrients are added, algae
  populations overgrow and use all of oxygen
  causing death to other inhabitants

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Rivers and Streams

• Rivers and streams flowing water moving in one
  direction
• Can be divided into different zones along their
  lengths
• Headwaters (at a lake, underground stream,
  melting snowpack) water is cold, clear, fast
  flowing, high oxygen ideal for fish such as
  trout

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Rivers and Streams

• Zones, continued
• Near middle of river width increases high
  diversity of fish, reptile, amphibian, and
  insects warming water, better for photosynthetic
  plants

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Rivers and Streams

• Zones, continued
• Mouth of river (where it flows into another body)
  slower water speed, sediment, lower oxygen
  availability, many bottom-feeder fish such as
  carp and catfish that eat dead organic matter the
  river has picked up along the way

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Rivers and Streams

• Rivers and streams are threatened by the same
  pollutants as lakes and streams
• They are also face destruction by the
  development of dams and channels

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Wetlands

• Wetlands areas of standing water that support
  emergent, or above-water, aquatic plants
• Comparable to tropical rain forests in the
  numbers of species supported
• Results from high nutrient levels found at land
  and aquatic environment interfaces

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Wetlands

• Over half of the wetlands in U.S. have been
  filled, drained, or otherwise degraded since
  European settlement
• Efforts in the last 25 years have slowed wetland
  depletion, but 58,000 acres of wetlands are still
  lost every year

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Saltwater

• About 75 of Earths surface is covered by
  saltwater, or marine, biomes
• There are 3 types of saltwater biomes
• Oceans
• Coral reefs
• Estuaries

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Rivers and Streams

• Oceans a biome consisting of open stretches of
  salt water
• Can be divided into four zones
• Areas near surface abundant light, largest
  number of phytoplankton (microscopic algae) that
  support most of the organisms inhabiting the ocean

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Rivers and Streams

• Deeper ocean zone
• Deeper area darker, colder, less oxygen,
  contain mostly decomposers which filter dead
  organic matter that drops from the surface

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Oceans

• Oceans have tides, regular fluctuations in water
  level caused by gravitational pull of the moon,
  which create
• Intertidal zones underwater during high tide and
  exposed during low tide

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Oceans

• Another unique oceanic zone is the abyssal plain
  very deep water, no sunlight, high pressure due
  to weight of water, surprisingly full of life

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Coral Reefs

• Coral reefs are unique biomes in that the
  structure is composed of skeletons of coral, the
  dominant organism
• Live coral are filter dead organic matter from
  the water and filter photosynthetic algae inside
  their bodies in a symbiotic relationship

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Coral Reefs

• Coral reefs are found throughout the tropics and
  provide for great biodiversity
• They are sensitive to environmental conditions
  and prone to bleaching, coral host expelling
  algae companions
• Global warming may be contributing to bleaching,
  which can be fatal to coral systems

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Estuaries

• Estuary where freshwater drains into salty
  oceans
• Vegetation can withstand the salt levels
• Called the nurseries of the sea, most
  commercial and recreational fish populations
  reside in them
• Lots of shellfish

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Estuaries

• The U.S. has some of the best known and
  economically important estuaries including
  Chesapeake Bay, Puget Sound, Tampa Bay
• Estuaries are threatened by human activities
  including eutrophication and loss to housing and
  resort development

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Human Habitats

• Humans have modified half of the Earths land
  surface (according to UN Food and Agriculture
  Organization)
• Mostly for agriculture and forestry, but 2-3 for
  habitation
• As population continues shift from rural to urban
  areas, this trend will continue as will
  environmental side effects

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