CHAPTER 9 COMMUNITY ECOLOGY
WHAT THE STORK
SAYS
A bird species in the Everglades reveals the
intricacies of a threatened ecosystem
9
WHAT THE STORK SAYS
A bird species in the Everglades reveals the intricacies of a threatened
ecosystem
At the end of this chapter you will
know:
Understanding the interconnectedness
between the pieces of an ecological
community may allow us to better
protect and help restore damaged
ecosystems..
Learning
Outcomes
9
WHAT THE STORK SAYS
A bird species in the Everglades reveals the intricacies of a threatened
ecosystem
At the end of this unit you will
know:
• Knowledge of ecological succession
can help ecosystem restoration.
• Species interactions contribute to
the overall viability of an ecosystem.
• Both biotic and abiotic features of a
system can be negatively impacted
by human activity
Main
Concept
Wood storks in Florida
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WHAT THE STORK SAYS
A bird species in the Everglades reveals the intricacies of a threatened
ecosystem
Case study:
Nesting pairs of wood
storks in the Florida
Everglades
experienced a rapid
and serious decrease
in population.
In their efforts to
restore the wood
stork population to
viable levels, scientists
found that the entire
ecosystem was at risk.
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The well-being of a species depends on the health of
its ecosystem
How does a system function the way it does? What are the characteristics that
allow some species to thrive, and how do the organisms interact with each other
and with the environment?
These are questions asked within the field of community ecology.
Community ecology also
includes understanding
how species contribute to
ecosystems services like
pollination, water
purification, and trapping
contaminants.
TERMS TO KNOW:
Community ecology
Indicator species
Ecosystems
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The well-being of a species depends on the health of
its ecosystem
Humans have interrupted the balance of the community
and changed the way the Everglades functions. The
wood stork case study has shown how minor changes in
an environment can have major changes in the overall
health of the ecosystem.
Ecosystem services
Carbon processing
Climate control
Contaminant capture
Economic resources
through raw materials
Energy conversion
Flood control
Food production
Nutrient storage
Photosynthesis
Pollination
Seed banking
Soil fertility
Storm protection
Waste elimination
Water purification
Water storage
Wind buffer
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Human alterations have changed the face of the Everglades
Former uninterrupted web of
natural ecosystems—marshes,
prairies, swamps, and forests.
South
Florida
today
Human alterations to the
Everglades have included resorts,
sugar plantations, and urban
centers.
Wood storks in the 1930s numbered
15,000−20,000 nesting pairs throughout
South Florida; now there are fewer than
4500 pairs.
Draining and development of the Everglades
was the norm throughout the middle of the
nineteenth and into the twentieth century.
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Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Loss of a single species can disrupt species health, movement of nutrients, and
energy flow through the ecosystem.
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Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Loss of a single species can disrupt species health, movement of nutrients, and
energy flow through the ecosystem.
9
Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Seemingly
small losses
lead to large
impact.
Loss of a single species can disrupt species health, movement of nutrients, and
energy flow through the ecosystem.
9
Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Seemingly
small losses
lead to large
impact.
Loss of a single species can disrupt species health, movement of nutrients, and
energy flow through the ecosystem.
9
Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Seemingly
small losses
lead to large
impact.
Loss of a single species can disrupt species health, movement of nutrients, and
energy flow through the ecosystem.
9
Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Energy is the basis of the food web with photosynthetic organisms capturing light
energy from the sun and storing it as sugars. Primary consumers—herbivores—eat
these plants for energy. Most energy is released as heat, but the remainder
supports metabolism and can become biomass of the consumer at the next level.
8
Matter and energy move through a community via
the food web
TERMS TO KNOW:
Food chain
Food webs
Producer
Consumer
Trophic levels
Energy is the basis of the food web with photosynthetic organisms capturing light
energy from the sun and storing it as sugars. Primary consumers—herbivores—eat
these plants for energy. Most energy is released as heat, but the remainder
supports metabolism and can become biomass of the consumer at the next level.
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Matter and energy move through a community via
the food web
Consumers are organized into trophic levels based on what they eat. Some
organisms feed at more than one trophic level.
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Producers set the
budget for the food in
a system through
their ability to convert
light energy into
chemical energy.
Matter and energy move through a community via
the food web
Nutrients cycle and
energy flows
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Primary consumers
eat primary
producers. Most of
the energy is released
as heat—the rest is
used to support
metabolism and a
small amount
becomes biomass.
Matter and energy move through a community via
the food web
Nutrients cycle and
energy flows
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Matter and energy move through a community via
the food web
Secondary consumers
eat primary consumers.
Nutrients cycle and
energy flows
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Matter and energy move through a community via
the food web
Quaternary
consumers eat tertiary
consumers. Because
such a small
percentage of energy
becomes biomass at
each successive level,
most terrestrial food
webs don’t go higher
than TL5.
Nutrients cycle and
energy flows
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Wood storks are
near the top of a
food chain that
begins with
sawgrass, cypress
and mangrove trees,
and phytoplankton.
Matter and energy move through a community via
the food web
Nutrients cycle and
energy flows
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The Everglades are shaped by biotic and abiotic factors
TERMS TO KNOW:
Detritivores
Decomposers
Gross primary productivity
Net primary productivity
(NPP)
Biotic (living) and abiotic (non-living) components of an
ecosystem are key to the ecosystem’s entire function.
In the Everglades, flooding from the rainy season allows fish
to reproduce and grow over thousands of acres.
As dry-down begins and the waters recede, foraging storks
follow the concentration of fish.
Connectedness between landscape and life is common in the
Everglades.
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The Everglades are shaped by biotic and abiotic factors
TERMS TO KNOW:
Niche
Habitat
Resilience
Species diversity
Species richness
Species evenness
Ecotones
Edge effects
Edge species
Core species
Ecosystem complexity increases as more
interactions exist and become part of stable
functioning. With more complexity come more
niches and greater survival potential for many
species. Along with more possible niches, a
complex community is generally more resilient to
change.
Diversity is qualified by richness—the variety of
species—and by evenness—relative abundance of
each species.
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The Everglades are shaped by biotic and abiotic factors
To measure richness and
diversity, the state is divided into
blocks. For each block, the
number of species present and
the representation (abundance)
of each species is compared.
With greater evenness, survival
of each species and of the
community is more stable.
In the example, each block has
423 species, but the relative
abundance of each species is
closer in the east coast example
than in the west coast.
Species of low abundance - more
likely to die out.
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The Everglades are shaped by biotic and abiotic factors
To measure richness and
diversity, the state is divided into
blocks. For each block, the
number of species present and
the representation (abundance)
of each species is compared.
With greater evenness, survival
of each species and of the
community is more stable.
In the example, each block has
423 species, but the relative
abundance of each species is
closer in the east coast example
than in the west coast.
East coast – greater diversity due to
more even abundance
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The Everglades are shaped by biotic and abiotic factors
Ecotomes occur when two distinctive ecosystems meet. The physical differences
between the two areas create edge effects, which either attract or repel some
species. Some species use a part of each community.
The mangrove trees and seagrass beds provide an example of an ecotome and its
use by snapper.
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The Everglades are shaped by biotic and abiotic factors
Ecotomes occur when two distinctive ecosystems meet. The physical differences
between the two areas create edge effects, which either attract or repel some
species. Some species use a part of each community.
The mangrove trees and seagrass beds provide an example of an ecotome and its
use by snapper.
9
The Everglades are shaped by biotic and abiotic factors
Ecotones occur when two distinctive ecosystems meet. The physical differences
between the two areas create edge effects, which either attract or repel some
species. Some species use a part of each community.
The mangrove trees and seagrass beds provide an example of an ecotone and its
use by snapper.
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Mangrove trees were a keystone
species that development and
other changes to land use
eliminated.
Change to keystones has a
greater impact on the
ecosystem than might
be predicted.
Changing community structure changes
community composition
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Mangrove trees were a keystone
species that development and
other changes to land use
eliminated.
Change to keystones has a
greater impact on the
ecosystem than might
be predicted.
Changing community structure changes
community composition
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Species interactions are extremely important for
community viability
TERMS TO KNOW:
Keystone species
Competition
Intraspecific competition
Interspecific competition
Successful communities are those
where a certain balance has
evolved between all the organisms
living there.
Purposes of interactions include
population and controls to
maintain carrying capacity.
More diversity means more
potential relationships.
Adaptations may bind one species to
another through competition for resources.
Other strategies also keep ecosystems
working. The interdependencies include
various levels of benefit to one or more
members of the community.
9
Species interactions are extremely important for
community viability
TERMS TO KNOW:
Keystone species
Competition
Intraspecific competition
Interspecific competition
Successful communities are those
where a certain balance has
evolved between all the organisms
living there.
Purposes of interactions include
population and controls to
maintain carrying capacity.
More diversity means more
potential relationships.
Adaptations may bind one species to
another through competition for resources.
Other strategies also keep ecosystems
working. The interdependencies include
various levels of benefit to one or more
members of the community.
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TERMS TO
KNOW:
Resource
partitioning
Symbiosis
Mutualism
Commensalism
Parasitism
Restoration ecology
Species interactions are extremely important for
community viability
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TERMS TO
KNOW:
Resource
partitioning
Symbiosis
Mutualism
Commensalism
Parasitism
Restoration ecology
Species interactions are extremely important for
community viability
9
TERMS TO
KNOW:
Resource
partitioning
Symbiosis
Mutualism
Commensalism
Parasitism
Restoration ecology
Species interactions are extremely important for
community viability
9
TERMS TO
KNOW:
Resource
partitioning
Symbiosis
Mutualism
Commensalism
Parasitism
Restoration ecology
Species interactions are extremely important for
community viability
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Ecologists and engineers help repair ecosystems
1992 – The Water Resources
Development Act enlisted the Army
Corps of Engineers to investigate
damage to the Everglades.
Canals and levees had dramatically
altered water levels, ecosystems were
being starved, affected by
hypersalinity, excessive nutrients, and
non-native species.
2000 – The Comprehensive
Everglades Restoration Plan (CERP)
began a 30-year plan for Everglades
restoration through 60 construction
projects.
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Ecologists and engineers help repair ecosystems
4000 square miles in
historic Everglades
Disruption and
drainage with negative
ecosystem results
CERP goal to restore
flow to historic
wetland areas
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Community composition changes over time as the physical
features of the ecosystem itself change
New species move into an area
where they hadn’t been before
and become established.
These pioneer species set off a
series of additional changes as the
plant community grows and
impacts abiotic conditions such as
shade and nutrient levels.
As one ecological community
replaces another, the changes are
largely predictable.
Change continues over time as
plants and animals progressively
replace their predecessors.
9
Community composition changes over time as the physical
features of the ecosystem itself change
New species move into an area
where they hadn’t been before
and become established.
These pioneer species set off a
series of additional changes as the
plant community grows and
impacts abiotic conditions such as
shade and nutrient levels.
As one ecological community
replaces another, the changes are
largely predictable.
Change continues over time as
plants and animals progressively
replace their predecessors.
9
Community composition changes over time as the physical
features of the ecosystem itself change
TERMS TO KNOW:
Ecological succession
Primary succession
Pioneer species
Secondary succession
Climax species
Climax community
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Community composition changes over time as the physical
features of the ecosystem itself change
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Community composition changes over time as the physical
features of the ecosystem itself change
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Community composition changes over time as the physical
features of the ecosystem itself change
9
Community composition changes over time as the physical
features of the ecosystem itself change
9
Community composition changes over time as the physical
features of the ecosystem itself change
9
Community composition changes over time as the physical
features of the ecosystem itself change
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PERSONAL CHOICES THAT HELP
U.S. Fish and Wildlife Service: http://fws.gov/news/blog
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UNDERSTANDING THE ISSUE
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UNDERSTANDING THE ISSUE
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ANALYZING THE SCIENCE
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EVALUATING NEW INFORMATION
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MAKING CONNECTIONS