Download Ecosystems and communities 4.3 * 4.5

ECOSYSTEMS AND
COMMUNITIES
4.3 – 4.5
Biology
 Ecological
succession is a series of more-or-less
predictable changes that occur in a
community over time.
 Ecosystems
change over time, especially after
disturbances, as some species die out new
species move in.
WHAT IS ECOLOGICAL SUCCESSION?
 Primary
succession begins in an area with no
remnants of an older community. The first
species that colonizes barren areas are known
as pioneer species.
WHAT IS THE DIFFERENCE BETWEEN
PRIMARY AND SECONDARY SUCCESSION?
 Secondary
succession occurs in disturbed
areas where remnants of previous ecosystems
– soil and even plants – remain.
WHAT IS THE DIFFERENCE BETWEEN
PRIMARY AND SECONDARY SUCCESSION?
 Undisturbed
succession
progresses to a point where it
produces a specific and stable
community. An example would
be “the magical forest”.
WHAT IS A CLIMAX COMMUNITY?
Clearing
and farming of tropical
rainforests can change the microclimate
and soil enough to prevent regrowth of
the original community.
CAN ALL ECOSYSTEMS RECOVER FROM
EXTENSIVE HUMAN-CAUSED
DISTURBANCES?
 Biomes
are regional climate communities. They are
described in terms of abiotic factors like climate and soil
type, and biotic factors like plant and animal life
 The
ten major biomes are tropical rain forests, tropical dry
forests, tropical grasslands, desert, temperate grassland,
temperate woodland/shrubland, temperate forest,
northwestern coniferous forest, boreal forest, and tundra.
WHAT ARE BIOMES AND HOW ARE THEY
DESCRIBED?
Aquatic
ecosystems are affected primarily by the
water’s depth, temperature, flow, and amount of
dissolved nutrients.
WHAT ARE AQUATIC ECOSYSTEMS
AFFECTED BY?
The
photic zone is the sunlit region near the
surface that allows photosynthesis to occur.
WHAT TERMS ARE USED TO DESCRIBE
WATER DEPTH?
 The
aphotic zone is below the photic zone. This is an
area so deep that light cannot reach it.
Photosynthesis cannot occur here.
WHAT TERMS ARE USED TO DESCRIBE
WATER DEPTH?

Benthos are aquatic organisms that live on, or in,
rocks and sediments on the bottoms of lakes,
streams, and oceans. The benthic zone, in shallow
water, can be home to algae and other aquatic
plants. When the benthic zone is too deep, below
the photic zone, chemosynthetic autotrophs are
the only primary producers.
WHAT TERMS ARE USED TO DESCRIBE
WATER DEPTH?
Rivers
and streams
Lakes
and ponds
Fresh
water wetlands
WHAT ARE THE THREE MAJOR CATEGORIES
OF FRESHWATER ECOSYSTEMS?
A
wetland is an ecosystem in which water
either covers the soil or is present at or near
the surface for at least part of the year.
WHAT ARE THE THREE MAJOR CATEGORIES
OF FRESHWATER ECOSYSTEMS?
 An
estuary is a special kind of wetland formed where
the river meets the sea.
 Estuaries
contain a mixture of fresh water and salt
water and are affected by the rise and fall of ocean
tides. They support an astonishing amount of biomass
which makes them commercially valuable. They
serve as spawning grounds for many ecologically
and commercially imported fish and shell fish
species.
WHAT IS AN ESTUARY AND WHY IS IT SO
IMPORTANT?
Ecologists
typically divide the ocean into
zones based on their depth and
distance from shore.
HOW DO ECOLOGISTS CLASSIFY MARINE
ECOSYSTEMS?
Costal
ocean
Open
ocean