Transcript Introduction to Ecosystems The Flow of Energy & Matter

Ecosystems &
The Flow of Energy & Matter
PACKET #80
CHAPTERS #54 & #50
Introduction
 Ecosystem
 Encompasses all the interactions among organisms living
together in a particular place, and among those organisms and
their abiotic environments
 Individual communities and their abiotic environments
 Earth, which encompasses the biosphere (all of Earth’s
communities) and its interaction with Earth’s water, soil, rock
and atmosphere, is the largest ecosystem
Ecosystems
ENERGY FLOW
Energy Flow Through Ecosystems
 The flow of energy is linear—as energy cannot be
reused by organisms


Energy begins as solar energy, which is trapped by
photosynthesis in the form of chemical energy
Chemical energy is then available to do work
Energy Flow II
 Energy flow describes
who eats whom in
ecosystems


A food chain describes the
sequential passage of
energy
A food web shows the
complexity of
interconnected food
chains

Remember that a food web
is composed of many food
chains
Energy Flow III
 Food Chain Refresher
 Primary producers are
autotrophs and comprise
the first trophic level
 Herbivores, primary
consumers, comprise the
second trophic level


May find omnivores here
Carnivores and/or
omnivores, comprise
trophics level three and
higher all the way to the
decomposers
Energy Flow IV
 Ecological Pyramid


Illustrates the trophic
levels
May be a pyramid of

Numbers
Energy Flow V
 Ecological Pyramid


Illustrates the trophic
levels
May be a pyramid of

Biomass
Energy Flow VI
 Ecological Pyramid


Illustrates the trophic
levels
May be a pyramid of

Energy
Ecosystems
PRODUCTIVITY
Productivity I
 Energy flow begins with primary productivity
 The amount of light energy converted to chemical energy, in
the form of organic molecules, by an ecosystem’s autotrophs,
over a given period of time.
 Gross Primary Productivity (kilocalories fixed per
area per time OR grams carbon fixed)

Expresses the total rate of photosynthesis of an ecosystem
 Net Primary Productivity (kilocalories fixed per area
per time OR grams carbon fixed)

The energy remaining after cellular respiration

Gross total productivity – energy used for cellular respiration
Productivity II
 Primary Productivity is
always expressed as a
RATE and is represented
via

Kilocalories fixed per area
per time


Joules per square meter per
year
Grams carbon fixed
(Biomass)

The dry weight of vegetation
added to an ecosystem per
unit area per unit time
 Grams per square meter
per year
Productivity III
 Rates of productivity are influenced by
environmental factors
 Tropical rain forests are the most productive
terrestrial ecosystems
 Wetlands, coral reefs, and estuaries are the most
productive aquatic ecosystems
Productivity IV
 Energy flow is never
100% efficient and
results in the Pyramid of
Productivity
Productivity V
 Relationship of productivity to biological diversity is
complex


Ecosystems may be more diverse as productivity increases, but
after a certain point, diversity will decline with increasing
productivity
Important when considering nutrient-enriched environments

Especially those that are impacted by human application of
fertilizers and enrichment by animal wastes.
Cycles of Matter in Ecosystem
Introduction
 Biochemical cycles are cycles of matter between the
abiotic and biotic components of the environment
 Carbon, nitrogen, phosphorus and water cycles are
central to life on earth
 Carbon, nitrogen and water cycles have atmospheric
components and cycle on a global scale
Carbon Cycle
 Carbon dioxide is the
pivotal molecule in the
carbon cycle
 Human activities, since
the beginning of the
Industrial Revolution,
have contributed an
increasing amount of
carbon dioxide to the
atmosphere by burning
fossil fuels
Nitrogen Cycle
 Bacteria are essential to
this cycle



Nitrogen fixing bacteria
converts nitrogen gas to
ammonia
Nitrifying bacteria converts
ammonia to nitrate
Denitrifying bacteria
converts, anaerobes, convert
nitrate to nitrogen gas
 Nitrogen is needed for the
production of proteins
 Nitrogen oxides are also an
ingredient in
photochemical smog
Phosphorus Cycle
 Fertilizers, runoff
containing animal
wastes, and sewage
introduce phosphorus
into aquatic ecosystems
 Phosphorus loss
accelerated by clear
cutting

Brazil
Water Cycle
 Enough said!
Abiotic Factors in Ecosystems
THE SUN
The Sun
 Warms the earth
 Solar energy
biogeochemical cycles
 Temperature changes
with latitude

Sun’s rays strike the
equatorial regions
vertically which result in
warmer temperatures
The Sun II
 Temperature changes with
season

Tilting of the Earth’s axis
causes the amount of solar
radiation to vary during the
year
 How does this help with
the establishment of ocean
currents?
 How does temperature
change help with support
life in standing bodies of
water?

More to come
Review