Principles of terrestrial ecosystem ecology.pdf

which cycles are soil pools and fluxes
largest? In which cycles are atmospheric
pools and fluxes largest?
2. How do the controls over the global carbon
cycle differ between time scales of months,
decades, and millennia? How has atmospheric
CO2 varied on each of these time
scales, and what has caused this variation?
3. How have human activities altered the
global carbon cycle? What are the mechanisms
that explain why some of the CO2
generated by human activities becomes
sequestered on land?
4. What are the major causes and the climatic
consequences of increased atmospheric
concentrations of CO2, CH4, and N2O?
What changes in human activities would be
required to reduce the rate of increase of
these gases? What policies would be most
effective in reducing atmospheric concentrations
of these gases, and what would be
the societal consequences of these policy
changes?
5. What are the major natural sources and
sinks of atmospheric methane? How might
these be changed by recent changes in
climate and atmospheric composition?
6. What are the major natural sources and
sinks of atmospheric N2O? How might
these be changed by recent changes in
climate and land use?
7. How have human activities changed the
global nitrogen cycle? How have these
changes affected the nitrogen cycle in
unmanaged ecosystems?
8. How do changes in the nitrogen cycle affect
the global carbon cycle? In what types of
ecosystems would you expect these nitrogen
effects on the carbon cycle to be
strongest? Why?
9. How have human activities changed the
global phosphorus and sulfur cycles? How
do changes in these cycles affect the global
cycles of other elements?
10. How have human activities changed the
global water cycle? If the world has so
Additional Reading 355
much water, and this water is replenished
so frequently by precipitation, why are
people concerned about changes in the
global water cycle? In what regions of the
world will changes in the quantity and
quality of water have greatest societal
impact? Why?
Additional Reading
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Bernstson, M. Kamakea, S. McNulty, W. Currie, L.
Rustad, and I. Fernandez. 1998. Nitrogen saturation
in temperate forest ecosystems. BioScience
48:921–934.
Cicerone, R.J., and R.S. Oremland. 1988. Biogeochemical
aspects of atmospheric methane. Global
Biogeochemical Cycles 2:299–327.
Galloway, J.N. 1996. Anthropogenic mobilization
of sulfur and nitrogen: Immediate and delayed
consequences. Annual Review of Energy in the
Environment 21:261–292.
Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J.
van der Linden, X. Dai, K. Maskell, and C.A.
Johnson, editors. 2001. Climate Change 2001: The
Scientific Basis. Cambridge University Press, Cambridge,
UK.
Matson, P.A., W.H. McDowell, A.R. Townsend, and
P.M. Vitousek. 1999. The globalization of N deposition:
Ecosystem consequences in tropical environments.
Biogeochemistry 46:67–83.
Reeburgh,W.S. 1997. Figures summarizing the global
cycles of biogeochemically important elements.
Bulletin of the Ecological Society of America 78:
260–267.
Schimel, D.S., et al. 2001. Recent patterns and mechanisms
of carbon exchange by terrestrial ecosystems.
Nature 414:169–172.
Schlesinger, W.H. 1997. Biogeochemistry: An Analysis
of Global Change. Academic Press, San Diego,
CA.
Smil, V. 2000. Phosphorus in the environment:
Natural flows and human interferences. Annual
Review of Energy in the Environment 25:53–88.
Vitousek, P.M., and P.A. Matson. 1993. Agriculture,
the global nitrogen cycle, and trace gas flux. Pages
193–208 in R.S. Oremland, editor. The Biogeochemistry
of Global Change: Radiative Trace
Gases. Chapman & Hall, New York.