Species questions: (checked 4/30/14)
1) 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
species?)
2) What is a) species richness, b) species evenness, and species diversity (scientific
definition). What’s the difference between species richness and species diversity?
3) Ecologists have examined the relationship between ecosystem processes (like NPP)
and species richness, with NPP being both an independent variable (on X axis) and a
dependent variable (on Y axis). Draw a graph where NPP is dependent upon species
richness, and show a) that more species always increase NPP, b) that up until a point but
no further, the number of species in a plot will increase NPP, and c) draw the relationship
with species as the dependent variable (Y axis), that shows that species richness is
maximized at intermediate levels of productivity (NPP on X axis).
3) Small plot studies show that the number of pre-existing species can exclude the
number of new species entering the plot. (Another (better?) way of saying this is that the
number of species in an area slows down the ability of new species to colonize the area.).
Why is that?
4) If the above is true, why then do we find that when we do whole landscape surveys
(like number of species in national parks), the graph showing the numbers of non-native
species increases with native species. (i.e., native species attract non-native species; or
new species are attracted to areas that already have lots of species?). How can a
relationship be negative at one spatial scale but positive at another spatial scale?
5) Why is it possible for a species to be dominant in an introduced environment, but not
dominant in its native environment?
6. Why are some ecosystems more invasible (likely to contain higher #s and relative
abundances of non-native species?)
7) 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?)
Causes and consequences of biotic change: (some of this material not covered until 5/2)
1.Provide two facts that suggest that directional climate change is already occurring.
2.What facts indicate that we have not exceeded the “historical range of variability” in
climate (at least locally/regionally)?
3.Why is cheatgrass viewed as an ‘ecosystem transformer’ in the Great Basin region, but
cheatgrass is not viewed as an ‘ecosystem transformer’ in the Front Range?
3b. Can you name another area where “grasslandification” is occurring? How about
desertification and shrublandification?
4. Our atmosphere is a) enriched with carbon dioxide and b) enriched with plant-available
forms of nitrogen (ammonium and nitrate). What plant group(s) (hint: photosynthetic
pathway) will be benefited from this change? Can you name any specific species? What
plant groups will not be benefitted?
5.List five general categories of factors associated with global environmental change.
5. How can one global change factor affect another? Give several examples.
6) what are the three major feedbacks (responses) of ecosystems that can influence
subsequent climate change? (we also asked this on exam 1…)
Ecosystem management.
1) What's the logic behind the statement, "All current ecological management activities
are experiments"? (hint: what’s our reference point?)
2) What's the logic behind the statement, "If you're not monitoring your management
activities, you have no scientific credibility!"
3) What are ecosystem services? What are the three types of ecosystem services? How
do these differ? What is your favorite ecosystem service?
4) What’s more important: maintaining biological diversity or maintaining ecosystem
functions? Are these completely compatible goals for conservationists and
environmentalists?
4) What do you get if you a) suppress fires 10x outside the historical range of variation,
b) overgraze, c) increase carbon dioxide by 1/3 and nitrogen deposition by about 10x, d)
alter the traditional hydrologic regime by retaining runoff and running irrigation ditches
across the land, and e) remove apex predators and expose the area to the presence of
about 100 new plant species…all over a short period of time?
(Hint: the answer is found along the South Boulder Creek trail, just south of Baseline.
Conservationists often call these ‘degraded systems’ but this represents the pool of
species that will form future ecosystems.)