Biodiversity Classwork
Classwork #1
Name: __________________________
6th Grade PSI
1. What is biodiversity?
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2. In the boxes below, create two ecosystems: one with low biodiversity and one
with high biodiversity. Explain the difference.
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6th Grade PSI
Disturbance & Biodiversity
Biodiversity Homework
Homework #1
Name: __________________________
6th Grade PSI
Source: http://www.nature.com/scitable/knowledge/library/biodiversity-and-ecosystem-stability-17059965
1. Describe how the diagram above shows the relationship between biodiversity
and resilience.
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6th Grade PSI
Disturbance & Biodiversity
Disturbance Classwork
Classwork #2
Name: __________________________
6th Grade PSI
Biotic and abiotic factors in ecosystems are interrelated. This means that, if one factor
changes, it will affect all the other factors in that ecosystem.
The marine Arctic ecosystem is a good example of this concept. Sea ice floats above
the water in the Arctic Ocean. This sea ice is an essential component of the ecosystem.
Ice algae are a type of algae that lives within nutrient-rich pockets of the sea ice. The
ice algae are eaten by zooplankton, which are microscopic invertebrates in the water.
The zooplankton are eaten by a variety of fish, including the Arctic cod, which is a
favorite food of the ringed seal.
Polar bears are also dependent on the sea ice. The majority of a polar bear’s diet is
ringed seals. Because polar bears live on the land, they use the sea ice as a platform
from which to hunt seals.
1. Draw a food chain below that describes the energy relationships in the marine
Arctic ecosystem.
2. As global climate warms, sea ice melts. This causes the ice algae population to
decrease. Describe how a decrease in the ice algae population affects the polar
bear.
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6th Grade PSI
Disturbance & Biodiversity
Disturbance Homework
Homework #2
Name: __________________________
6th Grade PSI
Pacific salmon are migratory fish. They hatch and mature in freshwater and then travel
to the ocean as adults. When it is time to spawn, the salmon return to the same
freshwater stream from where they were born. After making the strenuous journey back
to freshwater and then spawning, the Pacific salmon dies.
Pacific salmon are greatly affected by climate change. As the climate warms, glaciers
and snowpacks become smaller. This means that there is reduced stream flow in the
summer and fall. This makes it difficult for salmon to travel to and from the ocean. As
the climate warms, the water temperature also warms. Warm water temperatures make
the salmon more susceptible to predators and disease. Climate change produces
frequent strong storms, which creates runoff that carries toxins into the streams.
As the salmon population is affected, many other populations are affected as well.
Young salmon eat insects and plankton. Some species exclusively eat plankton. In turn,
salmon are preyed upon by bears, eagles and orcas.
1. Describe two ways that climate change disturbs the salmon population.
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2. A change in one part of an ecosystem will inevitably create changes in other
parts of the ecosystem. Describe how a decrease in the salmon population would
affect the following populations:
a. Plankton
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b. Bears
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6th Grade PSI
Disturbance & Biodiversity
Succession Classwork
Classwork #3
Name: __________________________
6th Grade PSI
After the eruption of Mount St. Helens, it took many years for vegetation to cover the
landscape again. After three years, vegetation covered only 1% of the landscape. After
14 years, 38% of the landscape showed vegetation. After 20 years, vegetation coverage
was 66%.
One plant that played an important role in the succession of
the ecosystem was the prairie lupine. The prairie lupine has
small, light seeds that blew into the area via the wind.
Although there was no nutritional value in the volcanic ash,
the lupine was able to grow because it has the ability to
obtain nitrogen directly from the atmosphere. This ability
enabled the lupine to create healthy soil around each
individual plant. Each lupine plant became a microhabitat,
enabling several other plants to grow. This, in turn, attracted
insects.
Source: http://en.wikipedia.org/wiki/Lupinus#/media/File:Lupinus_angustifolius_(1).jpg
1. Describe how soil is created during the process of succession. Use the prairie
lupine as an example.
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2. Create a graph of % vegetation coverage versus time, using the information
given. Remember to label your axes and give a title to your graph.
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6th Grade PSI
Disturbance & Biodiversity
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6th Grade PSI
Disturbance & Biodiversity
Succession Homework
Homework #3
Name: __________________________
6th Grade PSI
1. Prairie dogs often create disturbances in an ecosystem by tunneling through the
ground and disrupting vegetation. How would vegetation biodiversity differ in
areas that experience low, medium and high levels of prairie dog disturbance?
Refer to the intermediate disturbance hypothesis in your explanation.
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2. Compare and contrast primary succession and secondary succession. (Include
the terms pioneer species and climax community in your answer.)
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6th Grade PSI
Disturbance & Biodiversity
Answer Key
Biodiversity Classwork
Classwork #1
1. Biodiversity is the variety of species in an area.
2. Answers will vary.
Biodiversity Homework
Homework #1
1. In an ecosystem with low biodiversity, a disturbance will automatically lower the
number of individuals present. In an ecosystem with high biodiversity, a
disturbance will affect some species and not others. The unaffected species can
increase in population while the affected species decrease in population. Overall,
the ecosystem can retain the same health as before the disturbance. This is
called resilience. As biodiversity increases, resilience also increases.
Disturbance Classwork
Classwork #2
1. Ice algae  zooplankton  Arctic cod  ringed seal  polar bear
2. Since ice algae is the base of the food chain, if that population decreases, all
other populations will decrease. Since zooplankton no longer have a food source,
their population will decrease, followed by a decrease in Arctic cod, ringed seal
and then the polar bear.
Disturbance Homework
Homework #2
1. There is reduced stream flow making migration difficult. Warmer water
temperatures increase risk of disease. Storms wash toxins into the water.
2.
a. The plankton population would increase, since salmon eat plankton.
b. The bear population would decrease, since bear preys on salmon.
Succession Classwork
Classwork #3
1. The prairie lupine was able to grow despite the lack of nutrients. The lupine was
able to add nitrogen to the soil. As each plant and animal died in the
microhabitat, it decomposed and added nutrients to the soil.
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6th Grade PSI
Disturbance & Biodiversity
Vegetation Coverage After Eruption
% Vegetation Coverage
70
60
50
40
30
20
10
0
0
5
10
15
20
25
Time (years)
2.
Succession Homework
Homework #3
1. The intermediate disturbance hypothesis states that biodiversity will be highest in
areas that receive intermediate levels of disturbance. In areas of low disturbance,
the vegetation biodiversity would be low because only the best competitors will
survive. In areas of high disturbance, biodiversity would be low because only
hardy, fast growing species would survive. In areas of intermediate disturbance,
biodiversity would be high. In these areas, disturbance would be high enough to
prevent competitors from getting rid of other species. At the same time,
disturbance would be low enough to allow a variety of species, not just hardy
plants, to thrive.
2. Primary succession occurs in areas which have no life, such as a volcanic
eruption. In these areas, pioneer species are the first species to thrive. As these
species die, they decompose to create soil. Eventually, a fully functioning climax
community forms. In contrast, secondary succession occurs where a disturbance
has destroyed habitat but preserved soil. In these areas, recovery is faster. As
plants and animals return to the area and then die, the soil health is increased.
Eventually, just like in primary succession, a climax community forms.
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6th Grade PSI
Disturbance & Biodiversity