Transcript Principles of Ecosystems

Introduction to Environmental
Studies
• Ecology
the study of how plants, animals, and
microbes interact with each other and with
their physical environment
• Environmental Science
the study of how humans impact natural
ecosystems
The First Principle of Ecology:
everything is connected to
everything else
What are the implications of this
principle?
History of Environmentalism
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Thoreau and Emerson
John Muir
Gifford Pinchot
Theodore Roosevelt
Rachel Carson
1960’s
Earth Day
Most famous for his book,
Walden, which details simple
living in Nature
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Ralph Waldo Emerson
John Muir
Aldo Leopold
Henry David Thoreau
Gifford Pinchot
In the late 1800’s, he started
the Sierra Club, an
environmental organization still
going strong today
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Ralph Waldo Emerson
John Muir
Aldo Leopold
Henry David Thoreau
Gifford Pinchot
In the book Silent Spring, this
author and scientists warned of
the dangers of pesticides
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Aldo Leopold
Gifford Pinchot
Thoreau
Rachel Carson
Robert Underwood Johnson
Creator of the U.S. Forest
Service
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Theodore Roosevelt
Franklin Roosevelt
Aldo Leopold
Ronald Reagan
Henry David Thoreau
Changing Worldviews
• Expansionist Worldview
natural resources are unlimited and for our use
• Ecological Worldviews
– Conservation
wise use and management of natural resources
today will insure use for future generations
– Preservation
minimal use of nature – nature should not be
thought of as just here to serve humans –
nature deserves to exist for its own sake
Deep Ecology
Sustainable development – a
pattern of resource use that aims to
meet human needs while preserving
the environment so that these needs
will always be met in the future
Principles of Ecology
To understand environmental issues
and foster sustainable development,
humans should take lessons form
how ecosystems function …
Ecosystem – a group of plants,
animals, and microbes interacting
with each other and the physical
environment in a sustainable way
ecosystem size …
• very small … a small
pond … your back
yard
or very large …
biomes – large terrestrial
ecosystems
biosphere – the earth’s “superecosystem” … includes all life
forms and the physical
environments supporting life
ecotone – transitional region
between adjacent ecosystems
Categories of Organisms
(common to every ecosystem)
autotrophs – (producers) “selffeeding” – typically, green plants
heterotrophs – consumers and
detritivores and decomposers
types of consumers …
herbivores (primary consumers)
carnivores (secondary or tertiary
consumers)
omnivores (primary, secondary or
tertiary, depending on the meal)
decomposers (bacteria and fungi)
break down organic material
recycling nutrients in the process
detritivores and scavengers –
exploit the available energy in
recently dead organisms
Feeding Relationships
food chains
show the direction of energy flow
between organisms in an
ecosystem
food web
a more comprehensive model
showing all feeding pathways
trophic levels – steps on a food
chain
biomass – total mass of biological
material (living) – usually refers to
specific trophic level
Pyramid of Energy Flow
Heat
Heat
Tertiary
consumers
(human)
Decomposers
Heat
10
Secondary
consumers
(perch)
100
1,000
10,000
Usable energy
available at
each tropic level
(in kilocalories)
Heat
Primary
consumers
(zooplankton)
Heat
Producers
(phytoplankton)
Fig. 3-18, p. 49
biomass pyramid – shows the
relative proportions of biomass at
each trophic level
• in the most efficient ecosystems, there is
only about 10% of food energy available
for the next higher trophic level – what
happened to the other 90%?
• food chains in most terrestrial ecosystems
rarely go higher than four trophic levels
Biomagnification of DDT
DDT in fish-eating
birds (ospreys)
25 ppm
DDT in large
fish (needle fish)
2 ppm
DDT in small
fish (minnows)
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm,
or 3 ppt
Fig. 9-16, p. 197
Toxins in Food Chains
• bioaccumulation: the storing of toxins in
an organism over time
• biomagnification: an increase in the
concentration of toxins as you move
higher in a food chain
Non-feeding Ecological
Relationships
symbiosis – a close physical
relationship between two different
species
commensalism – one organism
benefits while the other is
unaffected
mutualism – beneficial to both
organisms
competition
• intraspecific – competition between
members of the same species – a major
force in Natural Selection
• interspecific – competition for limited
resources between different species
Abiotic factors – physical and chemical environmental
conditions that determine the types of plants and
animals in an ecosystem … examples?
optimum conditions – for every abiotic factor
there exists a certain level at which a species
does best
limiting factor – an environmental factor that
restricts the success of a species
range of tolerance – acceptable range of
environmental conditions for each species
Range of Tolerance
Lower limit
of tolerance
Few
organisms
Abundance of organisms
Few
organisms
No
organisms
Population Size
No
organisms
Upper limit
of tolerance
Zone of
intolerance
Low
Zone of
physiological stress
Optimum range
Temperature
Zone of
Zone of
intolerance
physiological stress
High
Fig. 3-11, p. 43
habitat and niche – the place where
organism is found and the role it plays
Ecosystem Sustainability
Energy – life depends on producer’s ability
to convert solar energy to chemical energy
in the form of organic molecules that
consumers can utilize
cellular respiration – the breakdown of
glucose to release energy for cell activity
energy flows “one way” through an ecosystem,
it can not be recycled
Second Law of
Thermodynamics
Solar
energy
Chemical energy
(photosynthesis)
Waste
heat
Mechanical
energy
(moving,
thinking,
living)
Chemical
energy
(food)
Waste
heat
Waste
heat
Waste
heat
Fig. 2-11, p. 32
continuity of life depends upon an
unending supply of nutrients
CHONPS – the “elements of life”
Nutrient Cycling
carbon cycle
nitrogen cycle
Ecological Succession
Succession- a series of regular predictable changes
occurring to an ecosystem after a disturbance
climax community- the end result of succession
characteristics- stable, sustainable
primary succession- begins with soil formation, occurs after
major disturbance
secondary succession- more common, faster
Seven Major Terrestrial Biomes
Precipitation and Temperature
Affects Biome Type
Polar
Tundra
Subpolar
Temperate
Coniferous forest
Desert
Deciduous
forest
Grassland
Tropical
Chaparral
Desert
Savanna
Rain forest
Tropical
seasonal
forest
Scrubland
Fig. 5-8, p. 84
• climatographs – a graph showing average
precipitation and temperature for a given
region
• net primary productivity – the amount of
energy available for consumers resulting
from photosynthesis
how is NPP related to temperature and
precipitation?
Net Primary Productivity in Major Life
Zones and Ecosystems
Terrestrial Ecosystems
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest
(taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Tundra (arctic and alpine)
Desert scrub
Extreme desert
Aquatic Ecosystems
Estuaries
Lakes and streams
Continental shelf
Open ocean
800
1,600
2,400
3,200
4,000
4,800
5,600
6,400
7,200
8,000
8,800 9,600
Average net primary productivity (kcal/m2/yr)
Fig. 3-20, p. 50