1. General Model Information
Name: Generalized Growth and Yield Model
Main medium: terrestrial
Main subject: biogeochemistry
Organization level: biocoenosis
Type of model: not specified
Keywords: forest, conifer pine, ponderosa pine, deterministic, growthprojections
Carleton B. Edminister
Rocky Mountain Forest and Range Experiment Station
240 W. Prospect Fort Collins
Phone: 970 498-1264
Fax : 970 498-1010
GENGYM (Generalized Growth and Yield Model) is a deterministic regression
type model that predicts growth of mixed conifer and ponderosa pine stands
in the southwest United States. Tree growth is projected in 1-inch wide
diameter classes (d.b.h.). Growth projections are given in ten-year increments.
The model was developed by Edminister and was validated using an error
propagation mixing and data splitting technique (Edminister et al., 1991).
Model data input requirements include:
- stem diameter (+ 0.10 in),
- number of stems per acre by diameter class,
- a site identification code, and
- the number of live trees per acre.
The model provides information about the future distributions of each
d.b.h class, height of trees in each d.b.h class, and age distributions.
The temporal scale of the model is 10 years, with the spatial scale at
the stand level. The model is written in Microsoft FORTRAN in the DOS environment.
Author of the abstract:
CIESIN (CONSORTIUM FOR INTERNATIONAL
EARTH SCIENCE INFORMATION NETWORK) :
II. Technical Information
Operating System(s): DOS
Programming Language(s): FORTRAN 77
III. Mathematical Information
Model Input Data Requirements: Number of driving variables (or % live crown). Stemdiameter (.10 Inches). Number of stems per acre by diameter class, site index, species.
Model Output Data: Tabular ASCII formatted future distributions of each d.b.h class, height oftrees in each d.b.h class, and age distributions.
Temporal Scale: Can be 10 year growth projects. One rotation length.
Spatial Scale: Stand level.
Edminister, C.B., H.T. Mowrer, R.L. Mathiasen, T.M. Schuler, W.K.Olsen and F.G. Hawksworth. 1991. GENGYM: a variable density stand tableprojection system calibrated for mixed conifer and ponderosa pine standsin the Southwest. USDA-FS Research Paper RM-297, Rocky Mountain Forestand Range Experimental Station, Ft. Collins, Colorado.
V. Further information in the World-Wide-Web
VI. Additional remarks
Global change implications: GENGYM is a model that can be used forglobal change research. It provides longterm information on conifer forestage and size structure. It could be an important model to understand thepotential affects of climate change on the over 10 million acres of conifersin Southwest.
Last review of this document by: T. Gabele : 17. Sep 1997
Status of the document:
last modified by
Tobias Gabele Wed Aug 21 21:44:43 CEST 2002