1. General Model Information

Name: SAGE

Acronym: SAGE


Main medium: terrestrial
Main subject: biogeochemistry
Organization level:
Type of model: not specified
Main application:
Keywords: grassland, carbon, nitrogen, sulfur, growth, roots, shoots, photosynthesis, aging, ion uptake, nutrient allocation, translocations, respiration, senescence, litterfall

Contact:

J.D. Hanson
Phone:
Fax :
email:

Author(s):

Abstract:

The plant component of SAGE simulates carbon, nitrogen and sulfur dynamics of three categories of grassland plants. Growth of roots and shoots is represented as an exponential function of young tissue carbon content. This function is then modified by temperature and moisture. Structural tissue is assumed to be synthesized with fixed carbon : nitrogen and carbon sulfur ratios. Carbon growth requirements, therefore, dictate nitrogen and sulfur growth requirements. ELM and SPUR use a similar approach for simulating plant nitrogen dynamics. Carbon growth is reduced if the nitrogen or sulfur levels in the plant are suboptimal. The processes simulated by the model are photosynthesis, aging, ion uptake, nutrient allocation, growth translocations, respiration, senescence, and litterfall.

Aboveground processes simulated in the SAGE model:

  1. Photosynthesis (atmospheric CO2 concentration, phenology or leaf age, temperature, solar radiation, leaf water potential)
  2. Growth (nutrient)
  3. Carbon allocation (variable allocation to nutrient ratio, phenology or leaf age, leaf area).
  4. Death (phenology or leaf age).
Belowground processes simulated in the SAGE model:
  1. Carbon allocation (variable allocation to soil nutrient ratio)
  2. Root growth (soil water, soil nutrient)
  3. Death (soil water, soil temperature)
  4. Uptake (soil nutrient, sulfur)
  5. Respiration (soil water, soil temperature).

(from: Hanson, J.D.; Parton, W.J.; Innis, G.S.; 1985 : Plant growth and production of grassland ecosystems: A comparison of modelling approaches. Ecological Modelling (29), P. 131-144.)

II. Technical Information

II.1 Executables:

Operating System(s):

II.2 Source-code:

Programming Language(s):

II.3 Manuals:



II.4 Data:



III. Mathematical Information


III.1 Mathematics


III.2 Quantities


III.2.1 Input

III.2.2 Output


IV. References

Hanson, J.D.; Parton, W.J.; Innis, G.S.; 1985: Plant growth and production of grassland ecosystems - A comparison of modelling approaches. Ecological Modelling (29), P. 131-144.

Lauenroth, W.K.; 1979: Grassland primary production : North American Grasslands. In : N. French (Editors), Perspectives in Grassland Ecology. Springer, New York, NY, P. 3-21.

Lauenroth, W.K.; Preston, E.M. (Editors), 1984: The effects of SO2 on a grassland : A case study in the Northern Great Plains of the United States. Springer, New York, NY, P. 207 ff.



V. Further information in the World-Wide-Web



VI. Additional remarks


Last review of this document by: T. Gabele: Tue Oct 7 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:49 CEST 2002

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