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					                       Habitats

Definition: types of places where specific kinds of plants and
    animals live. Within biomes, a variety of habitats exist
    where the physical environment shapes the biological
    environment.
Concepts:
1. Niche- the range of conditions that species tolerate (or
    prefer). It may be thought of as an n-dimensional (more
    than 3-dimension) space.
2. Community- a group of species found in a particular
    habitat. The species may or may not interact.
3. Diversity- a term that refers to the number of species in a
    community (species richness) and the relative population
    density (evenness) of these species.
          Southern New England Habitats I:
                   Barrier Beach


• Definition: areas of wind- and current-deposited sand that act as barriers
  between the ocean and upland. Much of the high energy (wind and wave
  action) of the coastal environment is dissipated on the barrier beach.
• Physical environment: This is an extreme and ephemeral, dynamic
  environment, in that it possesses difficult conditions for organisms to live
  in, and in that it continually changes shape and may disappear and
  reappear over time. Physical environmental features that organisms face
  include, wind, wave action, highly saline water, wind-borne salt spray, tidal
  fluctuation and shifting sands.
• Diversity: The richness of terrestrial species may be low, because few
  species possess the adaptations necessary to survive this extreme
  environment. The density of these species may be high, however. In
  contrast, the richness of marine species in the near-shore environment may
  be comparatively high.
       Topography: Intertidal Zone
• The intertidal zone is the region between high and low tide;
  that place where the ocean meets the land and expends
  much of its energy.
• At the upper end of the intertidal zone, algae and other
  debris carried by wave action are deposited at the wrack
  line.
                    The Berm
• The berm is the low region above high tide that is largely
  devoid of vegetation. Sea rocket and beach clotbur are
  among the few plant species that can colonize the upper
  reaches of the berm.
• It is characterized by wind-blown (aeolian) sand deposits
  that changes in profile from summer (more gently
  sloping) to winter (steeper profile).
                    Primary Dunes




• The primary dunes are wind-formed deposits of sand that are
  the first beach environment extensively colonized by terrestrial
  plants.
• This environment is characterized by wind-borne salt spray and
  shifting sands.
• The principal plant species of the primary dunes is dune grass- a
  species that produces a network of rhizomes (underground
  stems) that stabilizes the plant and the sand it occupies.
• Other common herbaceous species include seaside goldenrod
  and beach pea.
                      Back Dunes

• The back dunes are further from the ocean, and are less
  affected by wind and salt spray.
• With a less extreme environment, the diversity of plant species
  increases. Low woody species like beach heather and beach
  plum (present in foreground) also appear.
     Dune Forest
• Still further back from the
  ocean, the extreme effects
  of the coastal environment
  subside to the point where
  salt-tolerant trees can
  become established.
• Pitch pine, eastern
  redcedar, American holly,
  black cherry and shadbush
  are typical members of the
  dune forest.
                      Bay Edge




• The low energy and quiet water of the inland (bay) edge of
  the beach permits the development of a marsh fringe.
• This marsh is vegetated by grasses and other herbaceous
  species that can tolerate inundation by saline tidal waters.
Profile of a Southern New
 England Barrier Beach
Adaptations



              • Plants and animals must have adaptations to
                survive the high salinity, high energy, often
                dry environments of the beach.
              • Plants have adaptations such as waxy coatings
                (prickly pear cactus at left) on leaves to reduce
                evaporation of water, salt glands to remove
                excess salt from tissues, and net-like rhizomes
                to help anchor them to the shifting sands.
              • Animals such as the herring gull (above) also
                have salt glands at the base of the beak to
                remove excess salts from tissues.

				
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posted:8/19/2011
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