1. BIOZONE: None Textbook: None
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

2. 46 Gersmehl Diagram: Key Gersmehl Diagram: Rainforest
Gersmehl Diagram: Taiga
Disturbance Hypothesis graph

3. 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

4. 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

5. Skill
Construction of Gersmehl diagrams to show the inter-relationships between nutrient stores and flows between taiga, desert and tropical rainforest

6. 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

7. 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
Middle L p. 46
Use this model to help you set up your G. Diagram

8. 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

9. 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

10. 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

11. Application
Consideration of one example of how humans interfere with nutrient cycling

12. 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

13. 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

14. 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

15. Understandings
In closed ecosystems energy but not matter is exchanged with the surroundings

16. 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)

17. Biosphere 2 Large research facility owned by University of AZ
Experiments carried out weekly while humans live in the closed environment

18. 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.

19. 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.

20. Understandings
Disturbance influences the structure and rate of change within ecosystems

21. 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

22. 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

23. Disturbance Hypothesis Graph
Make observations about the graph. What do you notice?

24. 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

25. 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