Describe ecological succession

Question

Problem:

Q1. Ecological succession refers to:

1. Fairly predictable changes in species composition over time in a particular location.
2. Changes in species composition over millions of years on a continent.
3. Changes in species composition across an environmental gradient, such as from higher to lower altitudes.
4. Changes in species composition as a large-scale environmental factor such as temperature changes.

 

Q2. Which of the following are examples of ecological disturbances?

Check all that apply:

1. Strong winds of hurricanes blowing down trees.
2. The historically annual floods of the Nile river.
3. Changes in temperatures along a latitudinal gradient (e.g. from the Equator to the Arctic).
4. Running a lawnmower over your lawn.

 

Q3. Intermediate levels of disturbance often lead to higher diversity because:

1. Some species are not vulnerable to the disturbance and reach larger population sizes.
2. Frequent disturbance can bring new species to an area that were not there before.
3. It is easier for many species to resist disturbances if they occur not too rarely nor too frequently.
4. Both species that do well at low disturbance and those that do well at high disturbance are usually present.

 

Q4. In this lab, with the average number of fires per year at 0.2, what setting for the chance of fire spreading gave the highest average diversity over time?

 

Q5. In the ecological community represented in this lab, which species eventually dominate in low disturbance conditions?

1. Grasses and annuals
2. Blackberry bushes and white pine trees
3. Oak and hickory trees
4. Sugar maple and white pine trees

 

Q6. In the forest system you examined, which type of disturbance would cause species diversity to be most variable over time?

1. Small, infrequent disturbances
2. Small, frequent disturbances
3. Large, infrequent disturbances
4. Large, frequent disturbances

 

Q7. In a community with 200 species, under which conditions would Simpson's diversity index have the highest value?

1. 10 species have very large populations, and 190 species are present but with very small populations.100 species have about equal population sizes, and 100 species are very rare
2. .10 species have large populations, 180 species have small populations, and 10 species are almost never present.
3. All 200 species have roughly equal population sizes.

 

Q8. Imagine a species in this forest system is very resistant to disturbance, because it often doesn't burn in a fire. Which is the most likely effect (or lack thereof) on species diversity?

1. Disturbance resistance in an early-successional species will increase diversity at low disturbance levels.
2. Disturbance resistance in an early-successional species will have little effect on diversity.
3. Disturbance resistance in a late-successional species will have little effect on diversity.
4. Disturbance resistance in a late-successional species will increase diversity when disturbances are frequent and large.

 

Q9. If you wanted to specify that sugar maple trees have an additional 10% chance per year of dying and being replaced with grass, how would you change the transition matrix?

Check all that apply:

1. Add 0.1 to the Sugar Maple to Grass transition.
2. Subtract 0.1 from the Sugar Maple to Sugar Maple transition.
3. Subtract 0.1 from the Grass to Sugar Maple transition.

 

Q10. An ecologist wants to know if diversity in a forest system is likely to decrease when an invasive species is introduced. This invasive species is a fast-growing annual plant that grows on oak trees and kills them. The invasive species can only survive on living oak trees. The ecologist has the original model from this lab and another version of the model which includes transitions that involve the invasive species. To answer the research question, the ecologist should compare species diversity generated by the original model to diversity generated by which model described below?

1. A model in which oak has a positive transition rate to the invasive and the invasive has a positive transition to grass.
2. A model in which oak has a positive transition rate to the invasive and the invasive has a positive transition to oak.
3. A model in which the invasive has a positive transition rate to oak and oak has a positive transition to grass.
4. Bottom of Form

Give reasoning with your answer.