Exam 17: Change in Communities

Which of the following is not an abiotic factor that can be an agent of change?

Refer to the figure. Chapin et al. conducted their work in Glacier Bay in 1994. If we were to return today to his plots, what could we predict to find in his former ten year-old pioneer communities that had been dominated by low shrubs, herbs, mosses, liverworts, and lichens?

Refer to the figure. Figure 9 You are studying disturbance and succession patterns, focusing on data you collect in area 1, area 2, and area 3. Part A of the figure shows how the community type changed across each year sampled, and part B shows how the abiotic conditions changed across study years (no specific condition specified or units listed). - Evaluate the successional paths for all three areas to answer the following questions: a) What is hysteresis? b) Which area shows evidence for this condition? Explain your answer.

Which human activity can bring about shifts in communities to alternative stable states?

Refer to the figure. Figure 9 You are studying disturbance and succession patterns, focusing on data you collect in area 1, area 2, and area 3. Part A of the figure shows how the community type changed across each year sampled, and part B shows how the abiotic conditions changed across study years (no specific condition specified or units listed). -Answer the following questions: a) According to the data in in Figure 9, when did the disturbance occur? b) Which years would provide baseline data for these communities? Why is baseline data important? c) How many years did it take the abiotic conditions to return to levels similar to their original conditions? d) How many years did it take for the biotic communities in areas 1, 2, and 3 to return to their original conditions?

Refer to the figure. In Farrell's (1991) work on algal succession, the presence of limpets had what effect on the growth of algae?

Which statement about succession in the glaciers of Alaska is false?

The final theoretical stage of succession is called the _______ stage.

Refer to the figure. Figure 10 You are studying succession and colonization at two sites, site 1 and site 2. You sample the abundance of two species at the sites and determine their percent cover at each site and time period. Based on the data in Figure 10, does either site show evidence for facilitation? Why or why not?

In the dunes near Lake Michigan studied by Cowles, the dominant plant species in the early stages of succession was

Refer to the figure. The figure is derived from studies of algal succession in the presence and absence of the barnacle Balanus and limpets. Which condition is represented by the purple line (indicated by the black arrow)?

Refer to the figures. Figure 5 Figure 6 Figure 7 You are studying the impacts of a volcanic eruption that produces a lava flow that covers part of a grassland (Figure 5). You begin taking samples as soon as the area is safe to work in-about one year after the main eruption has ended. You set up a transect (beginning at "Transect start" in Figure 5), and then collect data on how several abiotic and biotic factors vary across it (Figures 6 and 7). -Answer the following questions: a) According to the data in Figure 6, what was the effect of the eruption on the percent of organic material in the soil along the transect? b) Based on Figure 5, predict how the eruption would have changed the amount of UV reaching ground level along the transect. Graph your prediction (this will be referred to as Figure 8). c) Based on the available resources, what type of succession would you expect along the transect? In both the blast zone and lava flow areas, how extreme are the conditions faced by the colonizer species? How would you expect the extent of extreme conditions to limit the species that could potentially colonize the areas?

Sutherland's experiments showed that the capacity of the tunicate Styela to dominate communities depends primarily on

Refer to the tables and the figure. Figure 11 You are studying succession and colonization at two sites, site 1 and site 2. You sample the abundance of two species at the sites and determine their percent cover at each site and time period.Answer the following questions: a) When are the sites most vulnerable to colonization by an invasive species? Justify your answer. b) By time 8, which site is least vulnerable to colonization by an invasive species? Why?

Refer to the figure. Figure 10 You are studying succession and colonization at two sites, site 1 and site 2. You sample the abundance of two species at the sites and determine their percent cover at each site and time period. Use the data in Figure 10 and your knowledge of the different successional paths that communities can follow to answer the following questions: a) Are the patterns of changes in abundance of species 1 and 2 consistent across the two sites? b) Based on the consistency of abundances of species 1 and 2 across the sites, how would you describe the successional patterns observed at sites 1 and 2? What might be driving this pattern?

Which statement about the amphibians that colonized the area around Mount St. Helens after the eruption is true?

Which manipulation(s) did Bertness and Shumway perform in their studies of succession in a New England salt marsh?

Which of the following would be considered a community stress?

Connell and Sousa criticized Sutherland's experiments on alternative stable states in fouling communities on the grounds that

Suppose that following a lava flow, pine grass (a hypothetical species) is the first species to colonize the area. Chemicals produced by pine grass change the soil chemistry in the environment, but these chemicals promote subsequent colonization by later species. Which model would best explain this scenario of succession?