Bark Beetles in Western Forests
I. General Questions: Based on Chapters 37 and 38 (all groups have the same general questions):
1. Compare the terms ecosystem, community, species, and population as they relate to ecology.
2. What is the difference between exponential and logistic growth? What are some density-dependent factors that keep populations from growing exponentially indefinitely? What are some density-independent factors?
3. What is an ecological niche? What happens when two species have identical niches? How does the fundamental niche differ from the realized niche?
4. Explain an example of resource partitioning, and explain how natural selection can lead to character displacement.
5. Describe an example of each of the three types of symbiosis discussed in your text.
6. Explain how energy moves through the living components of an ecosystem (starting with primary productivity and including a discussion of food webs and ecological pyramids).
7. Explain how water, carbon, and nitrogen cycle through ecosystems, and give at least one example for each of how human activities can alter the cycle.
8. Seven different biomes are described in your textbook. If you were in charge of global ecosystem conservation but were told you had to focus all of your resources on preserving two of the seven types of biospheres, which would you choose, and why?
II. Bark beetles in Western Forests
An infestation of Bark Beetles over the last decade or so is seriously threatening the forests of the Rocky Mountains, and could spread to impact forests throughout the entire western United States. Not only will this entail dramatic environmental change in the affected regions, but there will be large scale economic and recreational impacts as well. This case study explores the causes and effects of this infestation, and is a great example of two major themes in ecology – the interconnectedness of ecosystems and the role of positive feedbacks.
Read these two recent news articles for the basic background information you’ll need to get started, then use any additional resources you find that might be helpful.
1. Describe the history and extent of the current bark beetle outbreak in the western US.
2. Provide an overview of the life cycle of a bark beetle, and explain how it’s presence impacts the trees it infects.
3. What is the apparent role of climate change in this outbreak?
4. How is the bark beetle outbreak related to forest fires in affected areas?
5. How does the death of large areas of forest impact (associated with either the bark beetles alone, or increased fire intensity associated with the beetles):
a. The hydrologic cycle?
b. The carbon cycle?
c. The nitrogen cycle?
6. Explain two examples of positive feedbacks that are related to the bark beetle outbreak.