BIO 212
Environmental Biology
Fall 2014
Biodiversity and Productivity
(52 points)
Learning Outcomes:
Students will be able to:
1. Investigate the relationship between plant biodiversity and productivity.
2. Formulate a testable hypothesis.
3. Interpret the data collected.
4. Use student generated data to test a hypothesis.
5. Present the results from your experiment in both visual and written forms.
Refer to the following two articles. They can be obtained through links from the data website.
The Science Daily article: Biodiversity leads to higher productivity.
Van Ruijven, J. and F. Berendse (2003) Positive effects of plant species diversity on productivity in the absence
of legumes. Ecology letters 6:170-175. (I have only provided you with the first page – all you need)
Download and save this MS-Word document. You may type your responses right below the question. Please
use a different font so that I can easily differentiate between my question and your answer.
Using your own words, answer each of the questions below.
Introduction (18 points)
1) Why is the topic of plant diversity important? (2 points)
2) What is currently known about the relationship between plant diversity and net primary productivity?
(2 points)
3) Though the evidence from more than 400 published experiments is overwhelmingly clear, there are two
possible explanations for the phenomenon they demonstrate (this phenomenon is the relationship you
described in #2 above). (4 points)
Explain what these two explanations are.
4) The answer you gave in #3 above is also discussed in the first half of the Introduction of Van Ruijven and
Berendse (2003). Van Ruijven and Berendse (2003) point out a controversy in the second half of their
Introduction.
What is this controversy? (2 points)
5) Recall your experimental design. (You may need to look at the data to jog your memory.) Think about the
two explanations for your answer to #2 above. List two hypotheses that you can test with your
experiment. Getting these correct is key to successfully addressing the remaining questions/statements in
this lab. Check with me first if you want. (4 points)
6) Make a prediction for each of the hypotheses you listed in #5. One of these predictions should include
information that you listed in #4. (4 points)
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BIO 212
Environmental Biology
Fall 2014
Results (20 points)
7) Provide a table of your data with means ± standard deviations. This table with help you write your results.
(10 points)
8) Write a brief Results section in a manner that addresses your hypotheses. This is not a discussion! Nor do
you need to report on the outcome for every species. That is what the table is for. You want to write a
narrative that points out any differences or trends (use relative values!) that could be used to support or
that do not support your hypothesis. Don’t neglect the root rankings! (10 points)
Discussion (16 points)
(Address each hypothesis in a separate paragraph. For each hypothesis it would be best to include your
response to #9 & 10 together. Hint: For one of these hypotheses you should be discussing the possible
presence of a “super-species”.)
9) Based on the results, was each of your hypotheses supported? (It is good practice to reiterate your
hypothesis when you make this statement. E.g. My hypothesis that _________ was supported.) (4 points)
10. Explain how your data does/does not support your hypothesis. If you use the two references to support a
statement that you make, be sure that you properly cite those sources. (See the instructions from the
Lawn lab.) (4 points)
11. Do you think that the plants in the polyculture (Mix) divided up the resources as expected? Examine the
dry weight data and the root rankings. Did one species dominant above the soil and another dominant
below the soil? (2 points)
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There’s more on the next page
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BIO 212
Environmental Biology
Fall 2014
12. Below are partial results from
Palmer, M.W. and K.A. Chandler-Ezell (2001). Effects of initial plant species richness in microcosms: preliminary
results. Community Ecology 2(1):41049.
Compare your results to Palmer and Chandler-Ezell. Note: Do not try to compare your basil weights to their
basil weight. You cannot because a) their weights are per plant and your weights are for 4 plants. b) their
growing conditions were different than yours. Instead, look at the trends in terms of your hypotheses. Are
the trends in their data similar or different than yours? (2 points)
Mean above ground biomass (g) of individual
plants in pots.
Species
Basil
Borage
Cabbage
Lettuce
Marigold
Soybean
Tomato
Zinnia
Mean of all
species
1 species:8
plants
8 species:1
plant each
1:8
0.08
0.07
0.31
0.03
0.14
0.18
0.04
0.12
0.12
8:1
0.11
0.13
0.34
0.03
0.21
0.46
0.13
0.23
0.20
13. Limitations: What limitations were there on the experimental design / implementation (i.e. what would
you do differently if you were to do the experiment again with unlimited resources. Is there data you
would like to have that you could use to better address your hypothesis? (2 points)
14. Implications of research: Why are the findings of your research important and/or what future research do
you think should be done to continue to resolve the question(s)? (2 points)
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