Transcript C.2 Gersmehl Diagrams and ecosystems Essential

Sponge: Set up Cornell Notes on pg. 47
Topic: C.2 Gersmehl Diagrams and
ecosystems
Essential Question: Explain the
differences between an open and
closed ecosystem.
BIOZONE: None
Textbook: None
C.2 Gersmehl Diagrams and ecosystems
Explain the differences between an open and closed
ecosystem.
Key Vocabulary:
Gersmehl Diagram
Closed Ecological ecosystem
Disturbance Hypothesis
• 46
Gersmehl Diagram: Key
Gersmehl Diagram: Taiga
Gersmehl Diagram: Rainforest
Disturbance Hypothesis graph
Gersmehl Diagrams
Gersmehl diagrams describe energy flow and nutrient recycling of
different biomes
• A common method of demonstrating the cycling of nutrients within
the main “stores” of an ecosystem
Gersmehl Diagrams
• Arrows of varying thickness
represent nutrient transfer
• Circles of varying sizes represent
the size of the nutrient stores
Included in the diagrams:
• Input- nitrogen, carbon, minerals
• Output- loses of nutrients by
leaching and runoff
• Flows- such as leaf and needle fall
from biomass to litter, and uptake
of nutrients from the soil
Skill
• Construction of Gersmehl diagrams to show the interrelationships between nutrient stores and flows
between taiga, desert and tropical rainforest
Construct a Gersmehl Diagram: Rainforest
Always read the information first!
• Biomass is the main store of nutrients because the tropical rainforest has
tall, dense vegetation with many layers and multiple species
• Precipitation (P): rainfall is high all year
• Litter has a very small store of nutrients because of the high rate of
decomposition
• Soil has a very small store of nutrients because of leaching and low soil
fertility
• Weathering (W) is rapid because of high heat and humidity
• Leaching (Le) is high because of high rainfall (Leaching is the process of
extracting minerals from a solid by dissolving them in a liquid)
• Runoff (R) is high due to such large amounts of rain, that the soil cannot
absorb it at all
Construct a Gersmehl Diagram: Rainforest
• Biomass is the main store of nutrients because
the tropical rainforest has tall, dense vegetation
with many layers and multiple species
• Precipitation (P): rainfall is high all year
Use this model to help you set up your G. Diagram
• Litter has a very small store of nutrients because
of the high rate of decomposition
• Soil has a very small store of nutrients because
of leaching and low soil fertility
• Weathering (W) is rapid because of high heat and
humidity
• Leaching (Le) is high because of high rainfall
(Leaching is the process of extracting minerals
from a solid by dissolving them in a liquid)
• Runoff (R) is high due to such large amounts of
rain, that the soil cannot absorb it at all
Middle L p. 46
Construct a Gersmehl Diagram: Rainforest
• Biomass is the main store of nutrients
because the tropical rainforest has tall, dense
vegetation with many layers and multiple
species
• Precipitation (P): rainfall is high all year
• Litter has a very small store of nutrients
because of the high rate of decomposition
• Soil has a very small store of nutrients
because of leaching and low soil fertility
• Weathering (W) is rapid because of high heat
and humidity
• Leaching (Le) is high because of high rainfall
(Leaching is the process of extracting
minerals from a solid by dissolving them in a
liquid)
• Runoff (R) is high due to such large amounts
of rain, that the soil cannot absorb it at all
Construct a Gersmehl Diagram: Taiga
• Litter is the largest store of nutrients
because of the low rate of
decomposition as a result of low
temperatures
• Run-off is high. The ground is still
frozen when the snow is melting
• Biomass is relatively low because
conifers have only one layer of
needles and there is no undergrowth
• Transfer from biomass to litter is high
because of the constant supply of
needles falling from coniferous trees
• Soil stores are very small. Poor soil is
formed from glacial deposits and so
there is low soil fertility
• Weathering of rocks is slow because
of the cold
Middle R p. 46
Use this model to help you set up your G. Diagram
Construct a Gersmehl Diagram: Taiga
• Litter is the largest store of nutrients
because of the low rate of decomposition
as a result of low temperatures
• Run-off is high. The ground is still frozen
when the snow is melting
• Biomass is relatively low because
conifers have only one layer of needles
and there is no undergrowth
• Transfer from biomass to litter is high
because of the constant supply of
needles falling from coniferous trees
• Soil stores are very small. Poor soil is
formed from glacial deposits and so there
is low soil fertility
• Weathering of rocks is slow because of
the cold
Application
• Consideration of one example of how humans interfere
with nutrient cycling
An example of humans interfering with nutrient
cycling
• Collapse of marine fisheries
as a result of overfishing and
habitat loss has affected
nutrient cycling in the marine
environment
• The role of fish as nutrient
recyclers is critical
An example of humans interfering with nutrient
cycling
• Eighty percent of the nutrients that are used by primary producers
are supplied by fish
• Removal of fish in areas where nitrogen is low will affect primary
production by plants
• This has a negative effect on the herbivores in that community
– Ex: Estimates of nitrogen excretions rates for grey snapper in the Bahamas
were 456% higher in unfished area. The excretion rates of phosphates
were 451%
– The sea grass beds that are the key habitat for young fish may be affected
by this lack of recycled nutrients
Ecological Systems
• Most ecosystems are open
– Light enters and is trapped by plants
– Herbivores eat the plants and their
feces fertilizes the soil
– Minerals may be leached by water
after rain and be carried down river to
a new ecosystem
Understandings
• In closed ecosystems energy but not matter is
exchanged with the surroundings
A Closed Ecosystem
• A closed ecological system (CES)
does not rely on exchange of
matter with its surroundings
• Waste products must be used by at
least one other species
– Urine, feces, and CO² must be
converted into O², food, and H₂O
• This involves at least one autotroph
which can use waste products to
make food (as long as sunlight is
available)
Biosphere 2
• Large research
facility owned by
University of AZ
• Experiments carried
out weekly while
humans live in the
closed environment
Bio-Dome
• Bio-Dome is a 1996 American comedy film
• Parody of Biosphere 2
• The plot of the film revolves around two
clumsy, dim-witted slackers who, while on a
road trip, look for a toilet stop in what they
believe is a shopping mall, which in fact
turns out to be a "bio-dome", a form of
a closed ecological system in which five
scientists are to be hermetically
(completely) sealed for a year.
A Closed Ecosystem
• No natural system on Earth is considered to be a closed system
– BUT…the entire planet can be thought to be almost closed
– Large amounts of light energy enter the Earth and eventually return
to space as heat, but matter is not exchanged.
Understandings
• Disturbance influences the structure and rate of change
within ecosystems
Disturbances influence the structure and rate of
change in an ecosystem
• A disturbance is a new
environmental condition that affects
the structure and rate of change in
an ecosystem
• Natural
– Fire/flood/wind/insect invasion
• Humans- unnatural
– Clearing a forest/ building a homes or
a road/plowing a field
Disturbance Hypothesis
In 1975 Joseph Connell proposed
a new idea
• Disturbance hypothesis:
Disturbance is a common
phenomenon and can actually
have a BENEFICIAL effect on
species diversity in a community
– Ex: forest fire
Disturbance Hypothesis Graph
Make observations about
the graph. What do you
notice?
Disturbance Hypothesis Graph
Make observations about the graph.
What do you notice?
• Low disturbances will cause a
decline in diversity
– Only the species that are the best
competitors will dominate
• High levels of disturbance lower
diversity
– Only a few species can complete their
life cycle between disturbances
• Intermediate levels of disturbance,
are the most effective at maintaining
diversity
– There is enough time between
disturbances for a number of species
to colonize an area & slows the
growth of dominant species
Bottom p. 46
Skill
• Investigation into the effect of an environmental
disturbance on an ecosystem
Guidance
• Examples of aspects to investigate in the ecosystem
could be species diversity, nutrient cycling, water
movement, erosion, leaf area index, among others