Download Env Sci CH 8 #2

Do Now
• In what ways have humans altered
landscapes locally?
• Is this harmful or helpful to the natural
ecosystem?
• How have humans tried to reclaim
ecosystems locally?
CHAPTER 8 COMMUNITY ECOLOGY
WHAT THE STORK
SAYS
A bird species in the Everglades reveals the intricacies
of a threatened ecosystem
What is Community Ecology?
Community ecology is
the study of how a given
ecosystem functions.
Ecosystem function includes:
How space is structured
Why certain species thrive
How species interact
Community ecology also
includes understanding how
species contribute to ecosystem
services like pollination, water
purification, and nutrient cycling.
Wetlands like the Florida Everglades
provide important water management
services, the most important of which is
flood control.
Wetlands capture and store precipitation
and runoff, then release them
downstream slowly, reducing peak flood
levels during major rain events.
Clicker Question
The Florida Everglades wetlands are
extremely important because they:
A.capture and store large amounts of
participation.
B.recharge groundwater.
C.capture contaminants and excess
nutrients, converting them to safer
forms.
D.All of the above.
Community ecology also
includes understanding
how humans have altered
ecosystems.
In the Everglades, humans
have altered the landscape
with roads and canals.
Pollutants have upended the
balance of reactions that make
the Everglades function.
Do Now
• What is an indicator species?
• How do scientists use this as a way to
examine ecosystems?
• How are species related to one another
when you compare using a trophic
pyramid?
The Wood Stork is an indicator
species for the Everglades. It is
particularly vulnerable to
changes in the ecosystem and
can warn ecologists of
problems early on.
The Everglades were once ideal for
Wood Storks. In the 1930s, an
estimated 15,000–20,000 pairs
nested throughout the
southeastern United States.
But in 1948, Congress authorized a
plan to drain the Everglades. As
water levels changed, the wading bird
population dropped 90 percent from
1930s–1990s.
Ecologists would soon discover the
loss of even one species can disrupt
an entire ecosystem—from the health
of giant wading birds down to the
movement of matter and energy.
Do Now
• What did the scientists determine as the
culprit for the decline of Stellar Sea Lion
population in the North Pacific?
• How was this determined?
• What lessons can be learned from this and
applied to the issue with the Florida
Everglades?
Do Now
• How could you design an experiment to
test how the diet of the Stellar Sea Lions
would impact their population abundance?
• Would this be an observational study or an
experimental study?
Do Now
• How did dirt form on Earth?
• How is this important for understanding
ecological succession?
• List the ways an invasive species disrupts
an ecosystem? Be specific.
• What types of invasive species do we
have locally?
Asian Longhorned Beetle
ALB Tree Damage
ALB Tree Damage
Worcester Street Before
Worcester Street After
Bittersweet Vine
Bittersweet Vine
Though the Everglade
changes have been extreme,
changes to ecological
communities are the norm –
nature is not static.
Wetlands and other communities go through
ecological succession: the progressive
replacement of plant and animal species due to
changing conditions the plants create.
As conditions change, other
species better adapted to
those conditions move in and
displace previous residents.
Energy is the foundation of every ecosystem. It’s
captured through photosynthesis and passed to
organisms through the food chain.
An ecosystem may have dozens of food chains.
Linked together, they create a food web that
shows the connections in the community.
Food chains and webs help
ecologists track energy and
matter through a given
community.
Clicker Question
A food web is:
A. a collection of food chains linked
together.
B. a simple linear path that shows what
eats what.
C. a graphic that shows how animals
are related to each other.
D. None of the above.
As humans altered water cycles
in South Florida, there were
fewer fish for Wood Storks to
feed on.
As human development
expanded, Wood Storks had
to fly farther from their nesting
grounds to forage.
Wood Storks were not the
only species affected.
Each species has its own
niche, or unique role, in an
ecosystem.
Dams, dikes and bridges
caused the Everglades to stay
too wet or dry for too long,
killing off worms, grass shrimps,
and microbial communities.
This led to the decline of snakes, fish,
alligators, turtles, and wading birds
that fed on them.
Agriculture has introduced
synthetic nutrients that have
caused algae blooms,
choking off plant and animal
life.
Oceanfront forests have replaced mangrove forests
– a keystone species, one that impacts its
community more than its abundance would predict.
Alligators are also keystone
species. “Gator holes” hold
water during dry season,
providing refuge for fish,
invertebrates, and aquatic
plants.
Competition – the vying between organisms
for limited resources – is another way that
species interact.
Restoration ecology is the
science that deals with the
repair of damaged or
disturbed ecosystems.
In 2000, Congress enacted the
Comprehensive Everglades Restoration Plan
(CERP) to address declining water quality.
The Wood Stork population has
rebounded – possibly because
they have moved away from
South Florida to Central and
North Florida, Georgia, and
North Carolina.