Transcript Habitats - Bird Conservation Research, Inc.

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.