Transcript ecosystems - Cloudfront.net

Ecosystems consists of all the
organisms living in a community
as well as all the abiotic factors
with which they interact.
What is
missing
from
this
food
chain?
decomposers
Energy can be neither created
nor destroyed. It can only be
transformed to another form.
This is called the law of
conservation of energy.
In what way
is this food
web more
realistic
than the
food chain?
The food web
incorporates
consumers
that feed at
multiple
trophic levels
Primary Producers
• Who are the primary producers
of most terrestrial ecosystems?
• Plants
• Who are the primary producers
of most aquatic ecosystems?
• Microscopic algae and bacteria
(phytoplankton), and
multicellular algae and aquatic
plants.
Consumers
• Herbivores - primary consumers
• Carnivores - secondary
consumers
• Omnivores - can feed at
multiple trophic levels
Decomposers
• What organisms are
decomposers in most
ecosystems?
• Fungi and Bacteria
• What do the decomposers
do?
Primary Productivity
• The energy budget of an
ecosystem depends on its
primary productivity.
• What is gross primary
productivity? (GPP)
GPP represents energy available
to consumers in an ecosystem.
What
is Net Primary Productivity?
(NPP)
NPP =
GPP - R
Net Primary Productivity
• Why is NPP a more useful
measurement than GPP?
How is it that the open ocean has low net
productivity yet accounts for most of the
Earth’s total productivity?
Limiting Factors
• What sort of factors will limit
productivity?
• Light intensity
• Water
• Inorganic nutrients such as
nitrogen and phosphorus.
• CO2
Energy Partitioning Within the Food
Chain
Energy may
also be
expressed as
kilocalories
(kcal)
What does this
number
represent?
Energy Partitioning Within the Food Chain
This is also
called biomass
The energy
available for the
next trophic level.
Typically the amount of energy that
is eaten by an organism is not all
converted into waste, growth, and
used for cellular respiration.
What happens to the rest?
Energy Partitioning Within the Food Chain
Total Energy
Output:
Respiration
Heat Loss
Waste
This is also
called biomass
The energy
available for the
next trophic level.
Ecological Efficiency
• How much of energy is
actually available to the next
trophic level?
• Usually around 10% is
available
• Why is it that we don’t see
6th order consumers?
An ecological pyramid is a
diagram that shows the relative
amounts of energy or matter
contained within each trophic
level in a food chain
or food web.
Which has more energy, a quarter pound
of salad or a quarter pound of beef ?
How can the producers in the English
Channel support the consumers in this
ecosystem?
Answer: The primary producers
have a short life span and also
reproduce rapidly
How many individuals are
supported at the top level of this
ecosystem?
Chemical
Cycling
Biogeochemical Cycles/Cycles
of Matter – the way in which
elements, chemical compounds,
and other forms of matter are
passed from one organism to
another and throughout the
biosphere.
** The numbers represent water flow in
billion billion grams per year
Transpiration in Leaves
Open and Closed Stomata in a
Spider Plant Leaf
Humans Affect the Water Cycle by Changing
Land Use:
• Reduced vegetation (deforestation,
cultivation, etc.) reduces precipitation
retained in soil and increases amount that
runs off.
• Groundwater pumping depletes aquifers,
brings water to surface where it evaporates.
• Climate warming will melt ice caps and
glaciers and cause sea level rise and
increased evaporation. Water vapor is a
greenhouse gas.
Review of the Water Cycle:
http://studyjams.scholastic.com/studyjams/jams/science/ecosystems/water-cycle.htm
http://www.epa.gov/ogwdw/kids/flash/flash_watercycle.html
Carbon is a key ingredient in the
tissues of living things.
What are three large reservoirs
where carbon is found around
the earth?
In what process do plants use
carbon dioxide?
Human Activities Affect the Global
Carbon Cycle:
• Runoff brings carbon to aquatic
ecosystems.
• Deforestation and fossil fuel burning
increase atmospheric CO2.
• Atmospheric CH4 is increased through
livestock production, rice cultivation, and
water storage in reservoirs (microbes in
water-logged soils produce CH4).
Review of the Carbon Cycle:
http://studyjams.scholastic.com/studyjams/jams/science/ecosystems/carbon-cycle.htm
http://bcs.whfreeman.com/thelifewire/content/chp58/5802002.html
(conversion to
organic forms)
Why do organisms require nitrogen?
Nitrogen fixation occurs when
soil bacteria convert N gas into
ammonia at their roots.
Denitrification releases N gas back
into the atmosphere by a different
type of bacteria.
Human Activities Affect the Nitrogen Cycle:
• Burning fossil fuels, rice cultivation, and
raising livestock releases oxides of
nitrogen to the atmosphere.
• These oxides contribute to smog and acid
rain.
• Humans fix nitrogen by an industrial
process to manufacture fertilizer and
explosives.
Review of the Nitrogen Cycle:
http://bcs.whfreeman.com/thelifewire/content/chp58/5802004.html
http://www.biology.ualberta.ca/facilities/multimedia/uploads/ecology/ncycle.html
http://studyjams.scholastic.com/studyjams/jams/science/ecosystems/nitrogen-cycle.htm
Concept 46.3 Certain Biogeochemical Cycles
Are Especially Critical for Ecosystems
• Topsoil and dissolved nitrates are lost from farm fields
and deforested areas by wind and water runoff.
• The nitrates are deposited in aquatic ecosystems and
result in eutrophication— increased primary
productivity and rapid phytoplankton growth.
Decomposition of the phytoplankton can deplete
oxygen; other organisms cannot survive, and dead
zones form offshore in summer.
The Experimental Eutrophication of
a Lake
What does the loss of nitrates from the
deforested ecosystem tell you about the
water, and about how nitrates are normally
maintained in the ecosystem?
Review of the Phosphorus Cycle:
http://nortonbooks.com/college/biology/animations/ch37a03.htm
http://www.sumanasinc.com/webcontent/animations/content/phosphorouscycle.html
For which macromolecules do
organisms need phosphorus?
Plants absorb phosphorus from
the soil or from water.
What is going on in this picture?
We’ve Changed Our Tune
Erosion of Earth’s Ozone Shield: The
Ozone Hole Over the Antarctic
Erosion of Earth’s ozone shield: Thickness
of the ozone layer
Biogeochemical Cycles Affect Global Climate
Greenhouse Effect:
Earth’s surface re-emits energy in longer, less energetic
infrared wavelengths.
Some of this infrared radiation is absorbed by gas
molecules in the atmosphere (greenhouse gases).
The molecules are warmed and radiate photons back to
Earth’s surface, keeping the energy within the Earth
system as heat.
Biogeochemical Cycles Affect Global Climate
Greenhouse gases include H2O, CO2,
CH4, N2O.
Without the atmosphere, Earth’s average
surface temperature would be about
34°C colder than at present.
Global Temperatures Are Increasing
Ecological Challenges Can Be Addressed through
Science and International Cooperation
Governments have cooperated to support large-scale
initiatives, such as the Intergovernmental Panel on
Climate Change (IPCC).
International agreements include:
• Montreal Protocol to prevent depletion of UV-absorbing
ozone
• Kyoto Protocol to reduce emissions of greenhouse
gases
• Convention on International Trade in Endangered
Species (CITES), to conserve species by eliminating
international trade.
What organism conducts
nitrogen fixation?
What compounds are
necessary for cellular
respiration to take place?
Use these three ecology terms
(community, ecosystem, population)
to identify the following:
1) The mussels on the
Main St. Pier in Huntington Beach.
2) The Santa Ana River.
3) All of the biota (living organisms)
in Big Bear Lake.
1)What are the three steps in the
nitrogen cycle? What organism
performs the process?
2) Why is phosphorus necessary
to living organisms?
3) Name one source of carbon in
the atmosphere.
4) Water evaporates from the
leaves of plants in a process called: