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									Last set of study questions; causes and consequences of biotic change.

Nitrogen saturation:
1.If excess nitrogen deposition occurs:
In a forest that has excess ammonium (NH4), why should we expect these soils to become
more acidic?

2.What are the main activities or processes that contribute to the excess nitrogen released
by human activities?

3) what are the three major feedbacks (response) of ecosystems that can influence
subsequent climate change? (we also asked this on exam 1…)

4. According to Vitousek, we have more than doubled the amount of nitrogen added to
Terrestrial surfaces per year.
a) why (or how) could this nitrogen “slow down” greenhouse gas warming?
b) what‟s the major source(s) of this nitrogen?
c) how could the addition of nitrogen increase species richness in some areas but
   decrease it in others?

6.List five general categories of factors associated with global environmental change.

7. How can one global change factor affect another? Give an example.

8. Why are some ecosystems more invasible (likely to contain higher #s and relative
abundances of non-native species?)

9. Give examples where an invader species "changes the biogeochemical rules (are
transformers)" for the ecosystem that's been invaded. (Hint: think “grasslandification”.)

10) What appears to make certain species “super-invaders”, i.e., capable of becoming
dominant within an ecosystem? (e.g., how does knapweed appear to do this?)

11) What allows a plant species to be a dominant within an ecosystem? Why do
ecosystem ecologists pay so much attention to dominants? (and tend to ignore the rare

Ecosystem management.

1) What's the logic behind the statement, "All ecological management activities are

2) What's the logic behind the statement, "If you're not monitoring your management
activities, you have no scientific credibility!"
3) The loss of natural ecosystems – the replacement with ‟ novel ecosystems‟ – is now
viewed as what‟s happening across the continents. Why should new species change the
site biochemistry….and why should changed resource inputs (like carbon dioxide and
nitrogen) change the species?

4) Ecosystems that have been severely altered in their fire return intervals can change
substantially in their species composition and ecosystem characteristics.
a) what ecosystems are likely most effected? B) which are least effected? C) what‟s
more likely to alter an ecosystem, fire suppression or increased fire return intervals?
(think comparing Konza to the Boreal forest…?)

5) What do you get if you a) suppress fires 10x outside the historical range of variation,
b) overgraze, c) increase carbon dioxide and nitrogen deposition, d) alter the traditional
hydrologic regime by retaining runoff and running irrigation ditches across the land, and
e) expose the area to the presence of about 200 new plant species…all at the same time?
(Hint: the answer is found along the South Boulder Creek trail, just south of Baseline.
Conservationists often call these „degraded systems‟ but they indeed are „novel‟.)

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