Plant Ecology

1) Island A is 100 m2 and 1000 m from the mainland. Island B is 50 m2 and 1000 m from the mainland. Island C is 50 m2 and 10 m from the mainland. Compare Island A and B in one graph, and Island B and C in the other graph. For each comparison, demonstrate which island will have greater species richness. Be sure to label x- axis and important lines/points on the graph and designate which islands you are comparing.

Assume that ALL of the mainland plant species had many, extremely light seeds. (8 pts) What would this do to immigration rate? Which island would have the greatest species richness? Demonstrate by graphing all 3 islands on the graph below (be sure to label axes, lines, points).

Now assume that ALL of the islands had extremely high plant herbivory (and each island has the same herbivore pressure). What would this do to extinction rate for all 3 islands? Which island would have the greatest species richness? Demonstrate by graphing all 3 islands on the graph below (be sure to label axes, lines, points.

2) How does the core-satellite hypothesis explain the presence of a dominant species in a grassland dominated by annual plants?

Is this hypothesis most similar to Tilman’s R* theory, Grime’s CSR theory, or Hubbell’s neutral theory? Explain why?

3) For each question, circle whether it is TRUE or FALSE and then briefly EXPLAIN why.
a) True or false. γ (gamma) diversity tells us about resource (environmental) heterogeneity in a given area.

b) True or false. Plant communities that are resistant to disturbance are also resilient to disturbance.

4) CIRCLE (or highlight in RED) ALL factors that limit net primary productivity (NPP) from the list below.
A) Water
B) Nutrients (eg. nitrogen, phosphorus)
C) Climate
D) Competition
E) Herbivory
F) Nitrogen fixation
G) Nitrogen mineralization
H) Denitrification

5) Would you expect β-diversity to be greater in a forest that was clearcut (all the trees and understory was cleared away) or selectively logged (only trees of a certain size were felled/logged) 20 years ago? Explain why. ?

6) Create a species rank abundance plot that illustrates the abundance patterns for two different communities– community A has higher species richness and evenness than community B. Make sure to label your axes and lines. (4 pts)

7) In successional sequences on soil embankments from road cuts through forests, annuals are typically followed by short-lived perennials, which are typically followed by shrubs (e.g., Oregon grape, Salal). To assess which mechanism of succession was involved in the change from perennials to shrubs, an experiment compared the success of Oregon grape and salal where the perennials had been removed and when the perennials were present. The data are shown in figure.

a) Which mechanism of succession is supported by the salal data? Why?

b) Which mechanism of succession is supported by the Oregon grape data? Why?

8) Draw the results of a greenhouse experiment with Arabidopsis thaliana that show evidence for genetic variation for phenotypic plasticity.

9) Design an experiment to test the enemy-release hypothesis. First, state what the enemy-release hypothesis states (specifically in regards to invasive plant populations). Then briefly outline your experimental methods and state how your methods address the hypothesis. Define your response variable, treatments, and any potential traits you will measure.
Draw the results of your experiment if the enemy-release hypothesis is true. (Feel free to draw as many graphs as necessary
10) Fill in the blank with deterministic (D), stochastic (random) (S), or both D and S. (15 pts)

Competition is (a) ____________________________ factor(s) that affects succession.

Proximity to seed source is (a) _____________________________ factor(s) that affects succession.
Priority effects is (a) _________________________ factor(s) that affects succession.

In a primary succession site that is far away from seed source, you would expect

____________________________ factors to play a role early in succession, and

____________________________ factors to play a role later in succession.
11) Use 1 coexistence mechanism to explain why more variable precipitation may INCREASE native plant diversity (name and describe).
12) You collect 50 soil cores from underneath different individuals of an unknown plant species. You put soil from each core into a pot (50 pots) and plant 30 seeds in each pot. As a control, you also plant 30 seeds in potting soil (50 pots) and notice that only these potting soil seeds germinate. Which mechanism BEST explains this result? (2 pts)
A) Plasticity
B) Allelopathy
C) Belowground competition
D) Enemy-release hypothesis
E) Denitrification

13) Provide 1 mechanistic reason for why you might expect to see a negative relationship between native and invasive plant diversity at the local 1 m2 scale. (4 pts)

Explain how this relationship could be positive at a larger scale. (4 pts)

Draw a graph that shows the potential for both relationships. (4 pts)

14) State 2 large ways humans are altering the global carbon cycle. (6 pts)

15) Zavaleta et al. 2003 looked at the separate and interactive effect between different global change factors in California grasslands.
P = elevated precipitation
T = elevated temperature
N = nitrogen deposition
C = elevated CO2
Explain, what does the y-axis mean (ie. what does a negative versus positive number mean)? (3 pts)

Which single global change factor had the largest negative impact on all plants in this experiment? (2 pts)

Do these results suggest an interactive effect between different global change factors on California grasslands? How can you tell





Sample Solution