October 4: Terrestrial ecosystems, Processes and Reactions, Part I,  lecture material (pdf-file)

Read Chapter 5 of the textbook.

Important Definitions:

"Rubisco" = Ribulose Biphosphate Carboxylase (the enzyme that attaches CO₂ from the atmosphere to the sugar ribulose)

Note: The following parameters are usually annual !
NPP = Net Primary Production / Productivity
GPP = Gross Primary Production
R_aut = autotrophic (plant) respiration

NPP = GPP - R_aut
"true increment" = NPP - seasonal loss (e.g. due to grazing)
ANPP = aboveground NPP
BNPP = belowground NPP
ANPP ≅ BNPP for many ecosystems

NEP = Net Ecosystem Production = GPP - R_tot
R_tot = R_aut + R_herb + R_het
R_herb = herbvivore respiration
R_het = heterotrophic respiration = CO₂ emission from decomposers
often R_herb << R_het ≅ R_aut
NEP = NPP - (R_herb + R_het) ≅ true increment

October 6: Terrestrial ecosystems, Processes and Reactions, Part II,  lecture material (pdf-file)

1. Required Reading (besides Chapter 6 of the textbook!):

1. Earth's Biomes, from: Earth As a Living Planet, D.B.Botkin and E.A. Keller (3rd Edition, John Wiley & Sons, Inc), Chapter 1, pp. 174-182.
2. Vitousek et al., 1986: Human Appropriations of the Products of Photosynthesis, BioScience, 36(6), 368-373, 1986
   

2. Homework (graduate students only (!), I will give extra credit to undergraduates if handed in):
(due on Monday, October 17, 2005)
a) Contruct a simple soil organic matter (SOM) box model with the following properties: 

• influx is either continuous and approximately constant (like for instance in a tropical rainforest), or discontinuous as a once a year monthly input (like for instance in a mid-latitude deciduous forest)
• outflux is described as a continuous loss process proportional to the existing SOM

Choose a high (10 arbritrary units (a.u.)) and a low (1 a.u.) input per year (input = P = const.), and a decomposition parameter k (0<k<1; the kinetic parameter) in the high, medium, and low range  and run the model for a century using a monthly time step. Use Excel or a similar calculation program for this task. Each model (6 in total) on its own page.
Display/plot the results (SOM reservoir size vs. time) and the relation between influx and SOM reservoir size. Which model corresponds approximately to which real-world biome? Are all models in SS after hundred years? How long did it take to reach SS?  5 pts.

b) Summarize the biome(s) of your home state or country.

• What are the physical parameters that govern them?
  
• How have humans used them/disturbed them? 
• Do you have suggestions on how your fellow countrymen could improve their actions to sustain more biomass in those biomes?

    5 pts.