Transcript Section 3 - Trimble County Schools

Ecosystems
Ecology 4.3 Notes
Section 3
Ecosystems
Section 3
Objectives
• Describe each of the biogeochemical cycles.
Ecosystems
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Matter
• Unlike energy which moves in one
direction, MATTER is recycled within and
between ecosystems
Ecosystems
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Biogeochemical cycles
• Connects biological, geological and chemical
• Elements, chemical compounds, and other
forms of matter are passed from one organism
to another and from one part of the biosphere to
another
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Water cycle
Carbon & oxygen cycle
Nitrogen cycle
Phosphorous cycle
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Water Cycle
• The water cycle continuously moves water
between the atmosphere, the land, and the
oceans.
• Water vapor condenses and falls to Earth’s
surface as precipitation.
• Some of this water percolates into the soil and
becomes groundwater.
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Water Cycle, continued
• Other water runs across the surface of
Earth into rivers, lakes, and oceans.
• Then, the water is heated by the sun and
reenters the atmosphere by evaporation.
• Water also evaporates from trees and
plants in a process called transpiration.
Ecosystems
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Visual Concept: Water Cycle
Ecosystems
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Carbon and Oxygen Cycles
• Carbon and oxygen are critical for life on Earth,
and their cycles are tied closely together.
• The carbon cycle is the continuous movement
of carbon from the nonliving environment into
living things and back.
• Animals, plants, and other photosynthesizing
organisms play an important role in cycling
carbon and oxygen through an ecosystem.
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Carbon and Oxygen Cycles, continued
• Plants use the carbon dioxide, CO2, in air to build
organic molecules during the process of photosynthesis.
During photosynthesis, oxygen is released into the
surroundings.
• Many organisms, such as animals, use this oxygen to
help break down organic molecules, which releases
energy and CO2. Plants can use the CO2 in
photosynthesis.
• Respiration is the process of exchanging oxygen and
CO2 between organisms and their surroundings.
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Carbon and Oxygen Cycles, continued
• Carbon is also released into the atmosphere in the
process of combustion. Combustion is the burning of a
substance.
• Fossil fuels are formed from the remains of dead plants
and animals, which are made of carbon. The burning of
fossil fuels releases carbon dioxide into the atmosphere.
• Humans burn fossil fuels, such as oil and coal, to
generate electricity and to power vehicles.
Section 3
Ecosystems
CO2 in
Atmosphere
Photosynthesis
feeding
Volcanic
activity
Respiration
Decomposition
Human
activity
Erosion
CO2 in Ocean
Respiration
Uplift
Deposition
Photosynthesis
Fossil fuel
feeding
Deposition
Carbonate
Rocks
Ecosystems
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Nitrogen Cycle
• Nitrogen must be cycled through an ecosystem so that
the nitrogen is available for organisms to make proteins.
• The nitrogen cycle is the process in which nitrogen
circulates among the air, soil, water, and organisms in an
ecosystem.
• The atmosphere is about 78% nitrogen gas, N2. But
most organisms cannot use nitrogen gas. It must be
changed into a different form.
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Nitrogen Cycle, continued
• In a process called nitrogen fixation, bacteria
convert nitrogen gas, N2, into ammonia, NH3.
– Nitrogen-fixing bacteria live in the soil and on the
roots of some plants.
– Nitrogen may also be fixed by lightning.
– Nitrogen is also fixed when humans burn fuels in
vehicles and industrial plants.
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Nitrogen Cycle, continued
• Assimilation is the process in which plants
absorb nitrogen. When an animal eats a plant,
nitrogen compounds become part of the
animal’s body.
• During ammonification, nitrogen from animal
waste or decaying bodies is returned to the soil
by bacteria.
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Nitrogen Cycle, continued
• During nitrification, ammonia, NH3, is converted
to nitrite and then nitrate.
• During denitrification, nitrate, NO3, is changed to
nitrogen gas, N2, which returns to the
atmosphere.
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Ecosystems
N2 in
Atmosphere
Synthetic fertilizer
manufacturer
Uptake by
producers
Bacterial
nitrogen fixation
Denitrification
Reuse by
consumers
Decomposition,
excretion
NH3
Atmospheric
nitrogen fixation
Uptake by
producers
Reuse by
consumers
Decomposition,
excretion
NO3 and
NO2
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Phosphorus Cycle
• Like water, carbon, oxygen, and nitrogen,
phosphorus must be cycled in order for an
ecosystem to support life.
• The phosphorus cycle is the movement of
phosphorus in different chemical forms from the
surroundings to organisms and then back to the
surroundings.
Ecosystems
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Phosphorus Cycle, continued
• Phosphorus is often found in soil and rock as calcium
phosphate, which dissolves in water to form phosphate.
• The roots of plants absorb phosphate. Humans and
animals that eat the plants reuse the organic
phosphorus.
• When the humans and animals die, phosphorus is
returned to the soil.
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Ecosystems
Organisms
Land
Ocean
Sediments
Ecosystems
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Primary productivity
• The rate at which organic matter is created
by producers
• One factor is the amount of available
nutrients in the ecosystem
Ecosystems
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Primary productivity
• If a nutrient is in short supply, it will limit an
organism's growth.
• When an ecosystem is limited by a single
nutrient that is scarce or cycles very
slowly, this substance is called a limiting
nutrient.
Ecosystems
Section 3
In-class Assignment/Homework