1. General Model Information

Name: Range Plant Profiles

Acronym: RAPPS


Main medium: terrestrial
Main subject: biogeochemistry
Organization level: ecosystem
Type of model: compartment model, ordinary differential equations
Main application:
Keywords: rangeland ,range grass growth, grassland dynamics

Contact:

Phil Sims
Southern Plains Range Research Station
USDA-ARS-SPRRS 2000 18th Street Woodward, OK 73801
Phone: 405-256-7449
Fax : 405-256-1322
email: a03lcwoodward

Author(s):

Developed by USDA-ARS Southern Plains Research Station in Woodward, Oklahoma

Abstract:

RAPPS is a process-oriented, range grass growth simulation model. The model simulates the response of rangeland grasses to different climates and soils. RAPPS uses hourly temperature data to calculate net carbon assimilation and water loss through leaf stomata. These weather data can be input or generated using a weather simulation model. The carbon, water and nitrogen is then allocated to various tissues within plant.

RAPPS model output includes net photosynthesis, number of tillers in vegetative or reproductive status, number of leaves and roots, root length, density by depth, leaf area index, biomass of several plant organs, reserve carbohydrates, plant and soil water potential, nitrogen content of plant organs, and transpiration. The model currently simulates a single plant and extrapolates to the field level for a single growing season.

Validation Procedures: The leaf gas exchange portions of the model are being validated in the field. Within the next two years the plan is to validate the biomass production aspects of the model for several grasses.

How Model Functions: RAPPS uses hourly climatic data to calculate net carbon assimilation and water loss through leaf stomata. Climate data and soil physics submodels interact cyclically with the model to calculate the amount of water and nitrogen taken up through roots. The carbon, nitrogen, and water is then allocated to the various plant tissues based on the plants morphological status. Currently, RAPPS operates only for one growing season and with one grass species. Our goal is to implement RAPPS as a multi-year, multi-species model.

Author of the abstract:

CIESIN (CONSORTIUM FOR INTERNATIONAL EARTH SCIENCE INFORMATION NETWORK):


II. Technical Information

II.1 Executables:

Operating System(s): DOS or Windows

II.2 Source-code:

Programming Language(s): FORTRAN

II.3 Manuals:



II.4 Data:



III. Mathematical Information


III.1 Mathematics


III.2 Quantities

RAPPS requires coefficients describing the relationships

III.2.1 Input

RAPPS requires coefficients describing the relationshipsbetween environmental variables and photosynthesis and stomatal conductance. Realistic outputalso requires stress tolerance information and data relating the phenological status of the plant tothe environment. Hourly climatic data is used as an input or can be generated automatically usinglongitude and latitude input.
Model Input Data Source: Laboratory data was used to parametrize the leaf gas exchangeportion of RAPPS. Empirical field data concerning the phenological above and below grounddevelopment of grasses was also used. As more mechanistic information is acquired it will beassimilated into the model. Some of the output of RAPPS includes net photosynthesis, number of tillers

III.2.2 Output

Some of the output of RAPPS includes net photosynthesis, number of tillersin vegetative or reproductive status, number of leaves and roots, root length, density by depth, leafarea index, biomass of several plant organs, reserve carbohydrates, plant and soil water potential,nitrogen content of plant organs, and transpiration.

Temporal Scale: RAPPS is currently setup to simulate a single growing season.

Spatial Scale: RAPPS simulates a single plant and extrapolates to the field level.


IV. References

Dougherty, R.L., J.A. Bradford, P.I. Coyne, and P.L. Sims. Applying anEmpirical Model of Stomatal Conductance to Three C-4 Grasses. (In Press)

V. Further information in the World-Wide-Web



VI. Additional remarks

This model can be used to examine the effects of climate change oncentral United States grassland dynamics.
Last review of this document by: T. Gabele: 08. 07. 1997 -
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:48 CEST 2002

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