Study Questions: nitrogen saturation, invasive species, and global environmental 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?
4. What are the major differences of agroecosystems compared to pristine ecosystems in
terms of
a) the source(s) of energy used to grow plants.
b) the amount of nutrients exported from these systems in surface waters or
groundwater?
c) the ability of these systems to store carbon in plants and soils
5. According to Vitousek, we have more than doubled the amount of nitrogen added to
Terrestrial surfaces per year.
a) why 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. There are a lot of stories about climate change, about too much nitrogen, about
invasive species, etc. in the popular press. As scientists why do we find most of these
stories to be fairy tales?
8. Why are some ecosystems more invasible (likely to contain higher #s and relative
abundances of non-native species?)
9. What factor(s) make agricultural ecosystems perhaps the most invasible ecosystems
on earth?
10a. What's the argument for stating, "Invasive species are a serious threat to native
biodiversity."
10b. What's the opposite argument (specifically, that plant invaders will not exterminate
native species)?
10. Give examples where an invader species "changes the biogeochemical rules" for the
ecosystem that's been invaded. (Hint: think western riparian zones, think
“grasslandification”.
11) One scientist says "it's the presence of the new species (propagule pressure) and the
survivorship characteristics of this species that determines invisibility.
Another scientist says "it's all about resource preemption. If resources are available the
ecosystem can be invaded.”
What's the difference between these two views?
12) A third scientist states... "It really doesn't matter that much about the characteristics
of invasive species. It's that the ecosystem is so altered that the previously dominant
species are no longer competitive." What's that all about?
Ecosystem management.
1) What's the logic behind the statement, "All ecological management activities are
experiments"?
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 ‘synthetic’ or ‘adventive
ecosystems’ – is now viewed as what’s happening across the continents. How can
species introductions or losses change ecosystem function? How can changes in
resource additions (like increased nitrogen deposition) change ecosystem structure (the
species)?