Transcript Ecosystems and Human Interference

Ecosystems and Human Interferences
Chapter 48
Mader: Biology 8th Ed.
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Outline
Biotic Components
– Autotrophs
– Heterotrophs
Energy Flow
– Ecological Pyramids
Biogeochemical Cycles
– Hydrologic Cycle
– Carbon Cycle
– Nitrogen Cycle
– Phosphorus Cycle
Mader: Biology 8th Ed.
Nature of Ecosystems
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Biosphere is part of the atmosphere,
hydrosphere, and lithosphere that contains
living organisms.
– An ecosystem where organisms interact.
 Ecosystems characterized by:
 One-Way flow of energy.
 Cycle of materials from abiotic
environment through biotic
community.
Mader: Biology 8th Ed.
Biotic Components
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Autotrophs
– Require only inorganic nutrients and an
outside energy source to produce organic
nutrients.
 Producers
 Photoautotrophs
 Chemoautrophs.
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Heterotrophs
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Heterotrophs need a preformed source of
organic nutrients.
– Consumers
 Herbivores - Feed on plants.
 Carnivores - Feed on other animals.
 Omnivores - Feed on plants and
animals.
– Decomposers are heterotrophic bacteria
and fungi that break down dead organic
matter.
Mader: Biology 8th Ed.
Biotic Components
Mader: Biology 8th Ed.
Energy Flow and Chemical Cycling
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Energy flow occurs because as nutrients
pass from one population to another, all the
energy content is converted to heat, which
dissipates into the environment.
Chemicals cycle as organic nutrients are
returned to the producers.
– Excretion
– Death
– Cellular Respiration
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Energy Balances
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Energy Flow
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Food Web - Interconnecting paths of energy
flow describing trophic relationships.
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Ecological Pyramids
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A trophic level is composed of all the
organisms that feed at a particular link in a
food chain.
– In general, only about 10% of the energy
of one trophic level is available to the next
trophic level.
 Explains why few carnivores can be
supported in a food web.
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Ecological Pyramid
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Global Biogeochemical Cycles
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Chemical cycling may involve:
– Reservoir - Source normally unavailable
to producers.
 Fossil Fuels - Minerals - Sediments
– Exchange Pool - Source from which
organisms generally take chemicals.
 Atmosphere - Soil - Water
– Biotic Community - Chemicals move
along food chains, perhaps never entering
a pool.
Mader: Biology 8th Ed.
Hydrologic Cycle
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Fresh water evaporates from bodies of
water.
Precipitation on land enters the ground,
surface waters, or aquifers.
Water eventually returns to the oceans.
Mader: Biology 8th Ed.
Hydrologic Cycle
Mader: Biology 8th Ed.
Carbon Cycle
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Atmosphere is an exchange pool for carbon
dioxide.
– Fossil fuel combustion has increased the
total amount of carbon dioxide in the
atmosphere.
 Transfer Rate
Mader: Biology 8th Ed.
Carbon Cycle
Mader: Biology 8th Ed.
Greenhouse Effect
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Greenhouse gases allow solar radiation to
pass through atmosphere but trap heat
(infrared radiation) from escaping.
– Carbon dioxide, nitrous oxide, methane
 If Earth’s temperature rises, more water
will evaporate, forming more clouds and
setting up a potential positive feedback
loop.
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Earth’s Radiation Balances
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Nitrogen Cycle
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Atmospheric nitrogen is fixed by bacteria in
order to make it available to plants.
– Nodules on legume roots.
Nitrification - Production of nitrates.
Denitrification - Conversion of nitrate to
nitrous oxide and nitrogen gas.
– Balances nitrogen fixation.
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The Nitrogen Cycle
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Nitrogen and Air Pollution
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Acid Deposition
– Nitrogen oxides and sulfur dioxide are
converted to acids when they combine
with water vapor.
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Thermal Inversion
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Phosphorus Cycle
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Phosphorus does not enter the atmosphere.
– Sedimentary cycle.
 Phosphate taken up by producers
incorporated into a variety of organic
molecules.
– Can lead to water eutrophication.
 Biomagnification
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Phosphorus Cycle
Mader: Biology 8th Ed.
Sources of Water Pollution
Mader: Biology 8th Ed.
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Review
Biotic Components
– Autotrophs
– Heterotrophs
Energy Flow
– Ecological Pyramids
Biogeochemical Cycles
– Hydrologic Cycle
– Carbon Cycle
– Nitrogen Cycle
– Phosphorus Cycle
Mader: Biology 8th Ed.
Mader: Biology 8th Ed.