Biomes

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Biomes
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Terrestrial Biomes

• Tropical Rain Forest
• Tropical Dry Forest
• Tropical Savanna
• Desert
• Temperate Grassland
• Temperate Woodland and Shrubland
• Temperate Forest
• Northwestern Coniferous Forest (Temperate
  Rainforest)
• Boreal Forest (Taiga)
• Tundra

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Tropical Rain Forest

• Equatorial regions
• Abiotic factors
• hot and humid the entire year
• large amount of rainfall year round (thin,
  nutrient-poor soils since nutrients are washed
  away)
• Biotic factors
• vegetation broad-leafed evergreens, ferns,
  orchids, vines plants grow in layers
• canopy being the tallest layer
• understory layer underneath
• climate similar to conditions inside a
  greenhouse, thus producing many diverse species
  of plants
• resulting in a diverse animal community
• animals also occur in layers and are specialists
  to avoid competition
• largest diversity of animals live in tropical
  rain forest

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Tropical Dry Forest

• S/C America, Mexico, Australia, India
• Abiotic factors
• rainfall is seasonal rather than year round
  (monsoons)
• mostly warm, with wet/dry seasons
• Biotic factors
• during dry season, deciduous trees drop leaves to
  conserve water
• plants are drought-resistant

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Tropical Savanna

• Abiotic factors
• warm temperatures, compacted soils
• receive more rainfall than deserts but less than
  tropical dry forests
• Biotic factors
• area has a cover of grasses with isolated trees
• small groves of trees and shrubs which are
  drought-resistant
• frequent fires and large animals (rhinos,
  elephants) prevent some parts from becoming dry
  forest
• contain largest collection of grazing herbivores,
  along with their predators

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Desert

• Africa, Asia, Southwestern US, Mexico, S.
  America, Australia
• Abiotic factors
• very dry, receives less than 25 cm of rain a year
• deserts are determined by their amount of
  precipitation received, not temperature (can be
  hot or cold)
• large variation between day and night
  temperatures
• no trees to release water vapor into air via
  transpiration to form clouds, therefore heat from
  day is released back into atmosphere at night
• soils are rich in minerals but poor in organic
  matter (dry conditions prevent organic material
  from decaying)
• Biotic factors
• plants have few leaves to conserve water
• plants are well adapted to dry conditions and
  include cacti and succulents which have a short
  growth cycle
• animals include mountain lions, gray foxes, mule
  deer, pronghorns and desert bighorn sheep
• many are nocturnal and active at night

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Temperate Grassland

• Central US, Asia, Europe, Australia, S. America
• Abiotic factors
• warm/hot summers with cold winters
• largest variation in summer and winter
  temperatures
• moderate precipitation, but not enough to sustain
  many trees
• worlds most fertile soils (breadbasket) -
  grasslands are mostly found in the interior of
  continents
• Biotic factors
• rich mix of grasses which are resistant to
  drought, fires and cold
• periodic fires and heavy grazing of large grazing
  herbivores (buffaloes) help to maintain a
  grassland biome

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Temperate Woodland and Shrubland

• CA and Mediterranean Sea, S. Africa and Australia
• Abiotic factors
• hot, dry summers
• cool, moist winters
• semiarid area
• area is affected by ocean currents
• Biotic factors
• mix of shrub communities (chaparral) and open
  woodlands (areas of grasses and wildflowers)
• shrubs, such as manzanita bushes, contain
  flammable oil which present a constant threat of
  fires

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Temperate Forest

• eastern US, most of Europe - our biome
• Abiotic factors
• area receives year round precipitation
• warm summers, cold/moderate winters
• soil is fertile and rich in humus from decaying
  leaf matter
• Biotic factors
• mixture of coniferous and deciduous trees,
  shrubs, ferns mosses which also grow in layers
  (along with the animals)

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Northwestern Coniferous Forest (Temperate
Rainforest)

• Pacific NW and northern CA
• Abiotic factors
• abundant rainfall during fall/winter and spring
  (dry summers)
• leaf litter produces acidic soils
• mild temperatures modified by mild, moist air
  from Pacific Ocean
• Biotic Factors
• dominant tree are conifers (redwoods, spruce,
  fir, hemlock)

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Boreal Forest (Taiga)

• occurs along northern edge of temperate zone
• Abiotic factors
• long, cold winters w/short, mild summers allow
  the ground to thaw
• moderate precipitation with high humidity
• acidic soil
• Biotic factors
• dominate trees are conifers (spruce, fir)
• many animals either hibernate or migrate south
  during winters

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Tundra

• found in northern latitudes and high elevations
  in mountains
• Abiotic factors
• area characterized by permafrost (permanently
  frozen subsoil) which causes plants to be small
  and stunted (roots cant grow through permafrost)
• top few centimeters thaw in summer, producing a
  soggy/wet soil which attracts insects
• cold temperatures, high winds and short growing
  season limit plant growth
• along with deserts, the tundra receives little
  precipitation
• Biotic factors
• plants include mostly mosses, lichens, short
  grasses, dwarf trees
• animals include the largest of their species
  caribou, muskoxen, and migratory birds

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Misc.

• Mountain Ranges - as elevations changes several
  biomes can be formed (similar to changes in
  latitude)
• Polar Ice Caps - border tundra regions and are
  cold year round
• Two polar areas
• 1. Arctic Region (North Pole) no land, just
  thick ice, polar bears, seals, insects
• 2. Antarctica (South Pole) contains true land
  covered by ice 5km thick in some areas, penguins,
  marine mammals

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Aquatic Ecosystems

• divided into fresh and marine ecosystems
• Two main types of Freshwater ecosystems
• Flowing-water ecosystems
• Standing-water ecosystems

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Freshwater Ecosystems

• Flowing-water ecosystems includes creeks and
  rivers
• organisms adapted to the rate of water flow
• originate in mountains, usually from underground
  water sources and are turbulent and contain large
  amounts of dissolved oxygen (few plants)
• as the water continues downhill, it slows and
  carries sediments which then allows plants to
  grow
• Standing-water ecosystems includes lakes and
  ponds
• water flows in and out of the system to
  distribute nutrients, heat and oxygen
• relatively still waters allow plankton to live

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Freshwater wetlands

• areas in which water covers the land or is
  present at or near the surface for at least part
  of the year
• Three main types of freshwater wetlands
• bogs forms in rock depressions carved by
  glaciation grows thick mats of sphagnum moss
  which produces acidic conditions
• marshes shallow wetlands near river banks which
  may be covered by water during flooding
  contains rushes and cattails
• swamps wet year-round and look like flooded
  forests

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Estuaries

• wetlands which contain brackish water - formed
  where rivers meet the sea
• many are shallow, with the base of the food chain
  being detritus, which is then fed upon by clams,
  worms, sponges
• estuaries serve as breeding and spawning grounds
  for shellfish and fish
• also as habitats where animals feed and grow
  before heading out for open ocean as adults
• two main types of estuaries include
• a. salt marshes, which occur in temperate zone
  climates and are dominated by salt-marsh grasses
  (found on eastern coastline from GA to ME)
• b. mangrove swamps, which occur in tropical zone
  climates and are dominated by mangrove trees
  (Everglades in FL)

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Marine Ecosystems

• divided into zones based on light penetration
  (photic and aphotic zones) and into zones based
  on depth and distance from the shore
• the photic zone is the layer through which light
  penetrates deep enough for photosynthesis to
  occur, allowing algae and other producers to
  grow, forming the base of the food chain
• includes the top 200 meters
• the aphotic zone occurs below the photic zone and
  is permanently dark
• in the aphotic zone, chemosynthetic autotrophs
  are the producers that form the base of the food
  chain and produce carbohydrates from inorganic
  chemicals in the waters
• many bottom-dwelling animals depend on detritus
  drifting down from above

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Zones of the Ocean

• according to the waters depth include
• Intertidal zone
• Coastal zone
• Open Ocean

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• Intertidal Zone
• organisms constantly exposed to regular and
  extensive changes in their environment due to the
  change in tides
• part of the day they are exposed to the air,
  while at other times they are submerged below the
  water
• common animals include starfish and sea anemones
• Coastal Zone
• extends from the low-tide mark to the outer edge
  of the continental shelf (relatively shallow
  border that surround all continents)
• usually shallow, allowing photosynthesis occurs,
  producing the large kelp forests on the western
  US coast
• form habitats for many other organisms
• Coral Reefs
• occurs in areas with warm (tropical oceans),
  shallow (within 40 meters of surface), clear
  water (free of sediments)
• coral reefs exceed tropical rain forests in terms
  of productivity and diversity of animals

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• Open Ocean
• zone begins at the edge of the continental shelf
  and extends outward
• this the largest marine zone but is actually poor
  in nutrients and has a very low productivity (the
  oceans nutrients originate on land)
• waters surface contains phytoplankton within the
  photic zone, which forms the base of the food
  chain and also produce most of the worlds oxygen
• contains fish of all sizes (whales, octopus,
  swordfish)
• Benthic Zone
• zone extends from the coastal ocean through the
  open ocean and includes the bottom dwellers of
  the sea
• often depends on zones above for food and
  includes such organisms as clams, starfish,
  marine worms, sea anemones
• also includes deep-ocean vents where
  chemosynthetic producers form the base of the
  food chain