Transcript Ch 3 “Energy Flow In Ecosystems”

Ch 3
What is Ecology?
• Ecology is the study of interactions among
organisms and between organisms and their
environment
• The biosphere is the portion of the earth in
which all life exists
Levels of Organization
• Species- Group of organisms that are able to
produce fertile offspring
• Population- Group of individuals of the
same species living in a particular space
• Community- Group of interacting
populations of different species.
• Ecosystem- all the organisms living in one
place with their nonliving environment.
• Abiotic factors- non-living
part of an ecosystem
(sunlight, temperature,
water, soil type, humidity)
• Biotic factors- living parts
of an ecosystem (animals,
plants, & microorganisms)
• Make a list of the biotic &
abiotic parts of the salt
marsh food web on p. 71
“Energy Flow In Ecosystems”
Ch 3.2
• The source of energy
for almost all
organisms is the sun
• Plants, algae, and
some kinds of bacteria
capture solar energy &
produce food through
photosynthesis
Photosynthesis
• Leaves absorb sunlight, which drives a
series of chemical reactions that require
H2O and CO2
• The result is the production of sugar
(food) and water
carbon dioxide + water + light energy →
glucose + oxygen + water
• When an animal eats producers, it gets energy from the
food the producer made during photosynthesis
• So, producers get their energy directly from the sun
• While consumers get their energy indirectly from the
sun by eating producers or other organisms that eat
producers
What Eats What
Name
Energy Source
Examples
Producer
Makes its own
food
Consumer
Gets energy by
eating other
organisms
Eats only
producers
Eats only other
consumers
Grasses, trees,
algae & some
bacteria
Mice, starfish,
humans, ants
Herbivore
Carnivore
Cows, sheep,
deer, rabbits
Lions, hawks,
spiders, bass
Omnivore
Eats both
producers &
consumers
Bears, pigs,
humans
Decomposer
Breaks down dead Fungi, bacteria
organisms; returns
nutrients to the
soil or water
Respiration: Burning the Fuel
• How do organisms get the energy from their
food?
• During cellular respiration, sugar & oxygen
combine to produce CO2, H2O, & energy
• Energy is used through daily activities,
stored as fat or sugar, and/or to make more
body tissue for growth
Energy Transfer: Food Chains,
Food Webs, & Trophic Levels
• A transfer of energy occurs each time an
organism eats another organism
• Food chains, food webs & trophic levels are
used to trace the paths that energy flows
through an ecosystem
• Each time energy is transferred, less of it is
available to organisms at the next level.
• What accounts for the decreased amount of energy
at each level?
• Some energy is lost during the process of
changing food to energy.
• About 90% of the energy is used to carry out the
functions of living- producing new cells,
regulating body temp. etc.
• The remaining 10% becomes part of the
organism’s body, stored in its molecules.
• This 10% is all that is available to the next trophic
level when one organism eats another.
• Another way to understand the reduced amount of
energy at higher trophic levels is to think of how it
could be similar to the flow of money.
• Let’s say you pay $15 for a CD. How much of that
$15 actually goes to the band members? Very little
because your money passes through several
intermediates, each of whom takes a cut, before it
reaches the band
How does energy loss affect an
ecosystem?
• The energy loss
results in fewer
organisms at the
higher trophic
levels. For ex.
Zebras & other
herbivores
outnumber lions by
about 1,000 to 1
• The loss of energy
from trophic level
to trophic level
places a limit on the
number of trophic
levels in an
ecosystem.
• Ecosystems seldom
have more than
four or five levels.
The Cycling of Water
• Water Cycle- the
overall water on Earth
stays about the same
• Water moves between
the Earth’s surface &
the atmosphere
• The sun provides the
energy that drives the
water cycle
• Heat from the sun
evaporates the water from
the oceans, lakes & rivers,
moist soil surfaces, from
leaves of plants and from
organisms’ bodies.
• As water vapor cools in
the atmosphere, it
condenses & forms tiny
droplets in clouds
• When the clouds meet
cold air, water returns to
the Earth again as
precipitation- rain, sleet,
or snow.
• Since oceans cover most
of the planet, most
precipitation falls on the
oceans
• The precipitation that falls on land may evaporate again into the
atmosphere.
• Or, it may collect in streams & rivers that flow into the oceans
• Or, it may soak into the soil
• Water that soaks into the soil may be used immediately by plants or it
may seep down through the soil & rocks until it reaches a layer of rock
or clay where it can go no further
• This layer of underground water is called groundwater
How much of the Earth’s water is
available for human consumption?
• 97% of the Earth’s water is in the oceans
• Leaving only 3% freshwater
• However, 77% of that 3% is frozen in the icecaps and
glaciers
• 22% of the 77% is groundwater
• 1% of freshwater is in lakes, rivers, soil and atmosphere
• Thus, only a tiny fraction of the Earth’s water supply is
available for our use.
• The water we require for our everyday needs comes from
two sources: surface water and groundwater
Underground Treasures
• Some large cities, as well as many rural communities and
individual farms, depend on aquifers for their water needs
• The US has several huge aquifers that supply millions of
gallons of water for homes and agriculture
• This resource is tapped by drilling a well into the ground
until the hole reaches the groundwater
• Aquifers continuously receive water that percolates down
from the surface, but this process is very slow
• It may take millions of years for a large aquifer to form
• The problem with aquifers is
that people are pumping out the
water faster than it can be
replaced
• The water levels of many
aquifers are dropping rapidly
• The largest aquifer in the US,
the Ogallala Aquifer, is being
depleted rapidly
Carbon Cycle
• The sun is the
source of
energy that
drives the
Carbon Cycle
• What form is
carbon found
in the
atmosphere?
• Where does it
come from?
Cellulose, which makes up the walls of plant cells, contains
Carbon. What is the source
of this carbon?
•How does carbon become
part of an animal’s body?
•How is carbon released
from the body?
Human Impact on the Carbon Cycle
• Humans are overloading the carbon cycle.
• This carbon is not returned to the atmosphere until
the leaves fall or the plant dies and decays.
• Some plants, however, never completely decay.
Instead, they are covered by sand and silt.
• After millions of years underground, the plants
become coal, oil, or natural gas.
• When these fossil fuels are burned, they release
the stored carbon as CO2
• Tons of CO2 are poured
into the atmosphere each
year from power plants
that burn coal or oil and
from cars that burn
gasoline.
• The burning of living
plants also releases CO2.
This increases the CO2 in
the air in 2 ways.
• First, a burning plants
gives off CO2. Second,
when a living plant is
burned, there is one less
plant to remove CO2 from
the air by photosynthesis.
Greenhouse Gases and the Earth’s
Temperature
• Greenhouse gases trap heat near
the Earth’s surface
• Major green house gases
include: CO2, CFCs, methane,
and nitrous oxide
• Many scientists believe that as a
result of increasing greenhouse
gases, the Earth’s average
temperature will increase by 4
degrees by 2050.
Weather Patterns
• If the earth heats up significantly, the oceans
will absorb more heat energy, which may make
hurricanes and typhoons more common
• It’s possible that global warming will also cause
a change in ocean current patterns which could
significantly affect the world’s weather
• Some regions could receive more rain than
normal, while others might have less
• Severe flooding could occur in some regions at
the same time that droughts devastate other
regions
Sea Levels
• As polar regions
warm, more icebergs
may break loose from
glaciers and melt in
the sea
• Sea levels would then
rise causing flooding
in some coastal areas
Slowing the Temperature Change
• Reduce the use of fossil fuels
• Preserve forests
• Plant trees
The Nitrogen Cycle
• All organisms need nitrogen to build
proteins
• Nitrogen gas makes up 78%of the
atmosphere
• However, nitrogenfixing bacteria are
the only organisms
that can use it
• Nitrogen-fixing
bacteria are an
important part of the
nitrogen cycle b/c
they take the
atmospheric
nitrogen and “fix” it
into a useable form
for other organisms
• These bacteria are
found in the roots of
beans, clover, &
peas.
Mutualistic Relationship
(nitrogen-fixing bacteria and plants)
• The bacteria use sugars made by the plant
and in exchange produce nitrogen for the
plant
• The excess nitrogen is released into the soil
• Animals get nitrogen by eating plants or
other animals
• Bacterial and fungal decomposers break
down wastes (urine, dung, leaves and other
plant parts) and dead organisms, returning
the nitrogen they contain to the soil
• After it is returned to the soil, bacteria
change a small amount of it into nitrogen
gas
1. What source of energy ultimately drives
the nitrogen cycle.
2. How do animals obtain
nitrogen?
3. In what form does
nitrogen appear in the
air?
Niche & Habitat
• Niche- Relationships with the environment,
both living & non-living parts.
• An organism’s niche is its way of life: when
it reproduces, where it finds shelter, how
many offspring,what time of day it is most
active, etc).
• Habitat is the actual place where an animal
lives. Examples: savanna, desert, rain forest.
• Choose an animal & describe the difference
between that animal’s habitat & niche.
How Species Interact With Each
Other
5 major types of species interactions:
1. Predation- one organism kills & eats
another organism
• Predator- one that does the eating
• Prey- one that is eaten
2. Competition occurs
when 2 or more
organisms of the same
or different species
attempt to use the
same limited resource.
• Plants also compete
for the limited amount
of sunlight that
reaches the forest
floor.
3. Parasitism- organisms that live in or on
another organism and feed on it without
immediately killing it.
• Parasites live on hosts.
• Only the parasite benefits in this
relationship.
4. Mutualismpartnership between 2
species in which both
species benefit.
• Example of a
mutualistic
relationship: clownfish
& sea anemones
5. Commensalism- most
rare of the 3 interactive
relationships
(parasitism, mutualism
& commensalism).
• Relationship in which 1
species benefits and the
other is neither harmed
nor helped.
Shark & remoras
How Ecosystems Change
• Succession is a regular pattern of changes
over time in the types of species in a
community.
Changes in Ecosystems
• Ecosystems change over
time
• Changes result from
natural events such as
floods, forest fires, or
volcanic eruptions
• Some changes are due to
human activities, like the
clearing away of forests or
filling in of wetlands to
make land available for
homes
Two Types of Ecological Succession
Type 1: Primary Succession
• Succession that occurs in an
area where no communities
exist is called primary
succession
• Primary succession may take
place in an area that is
devastated by a volcanic
eruption or when a glacier
retreats to expose bare rock
• The main process that takes
place during primary succession
is the development of new soil
• The first organisms to
inhabit an ecosystem are
called pioneer species
• Lichens, fungi and mosses
are pioneer species in
primary succession b/c they
help make new soil
PRIMARY SUCCESSION
•
•
Secondary Succession
• In areas where organisms previously
lived, secondary succession takes place.
• This type of succession may occur after a
forest is cleared or a field is abandoned
• In secondary succession, pioneer species
are usually fast-growing grasses & small
shrubs
• Pioneers are plants that first move into a
new area and start the process of succession
• Most are grasses and weeds
SECONDARY
SUCCESSION
PRIMARY vs SECONDARY SUCCESSION
Primary Succession
Secondary Succession
Occurs on surfaces
where no ecosystem
existed before
Occurs on surfaces
where an ecosystem has
previously existed
Examples: new islands
created by volcanic
eruptions & in areas that
were covered by glaciers
Examples: old-field
succession which occurs
when farmland is
abandoned
Climax Community
• When change affects an ecosystem, the parts of the ecosystem
typically react in a way that strives to restore the ecosystem
• Once succession begins & some plantlife is established in an
area, small animals that feed on these plants will begin to return
• In time, diversity in the number and kinds of species in the area
is restored & a stable, mature community called a climax
community inhabits the area
Reason For Concern
• Environmental damages and losses adding
up to more than $138 billion per year
• Approximately 50,000 foreign species and
the number is increasing
• About 42% of the species on the Threatened
or Endangered species lists are at risk
primarily because of non-indigenous
species.
http://www.news.cornell.edu/releases/Jan99/species_costs.html
http://www.invasive.org/eastern/images/1536x1024/2307255.jpg
Kudzu
• 1876 at the Philadelphia
Centennial Exposition
• From 1935 to the mid1950s, farmers in the
south were encouraged
to plant kudzu to reduce
soil erosion
• Kills or harms other
plants by smothering
them under a solid
blanket of leaves
• Kudzu grows approx. 1
ft/day
•
•
•
•
•
Japanese Honeysuckle
Eastern Asia
Introduced into NY in 1806 as an
ornamental plant and ground cover.
Aggressive grower
Prolific seed producers
Able to out-compete native species
for nutrients and water.
www.dnr.state.oh.us/.../ 9japhoneysuck.htm
Water Hyacinths
• Invasive, aquatic
plants are altering fish
and other aquatic
animal species,
choking waterways,
altering nutrient
cycles, and reducing
recreational use of
rivers and lakes.
• $100 million is spent
annually in non-native
species aquatic weed
control (OTA 1993).
Tree-of-Heaven
aka Stinking Sumac
www.invasivespecies.gov/.
• Central China
• Pennsylvania gardener in
1748
• 42 states, from Maine to
Florida and west to
California.
• Common in urban areas
where it can cause damage to
sewers and structures
• Biggest threat to environment
b/c of its invasiveness in
cultivated fields and natural
habitats.
• A prolific seeder & grows
vigorously, establishing dense
stands that displace native
plants.
• Produces chemicals that kill
or prevent other plants from
growing in its vicinity.
Kentucky Non-Natives
Tuberous Sweet Pea
Musk Thistle
http://dnr.wi.gov/invasives/photos/index.asp?SF=Common
 Queen Anne’s Lace
Kentucky Bluegrass
http://dnr.wi.gov/invasives/photos/index.asp?SF=Commo