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Forest Biometrics and

Ecological Modelling Lab

U.J. Noblet Forestry Bldg.
1400 Townsend Drive
Houghton, MI 49931


This web site is the home for research at Michigan Tech involving the Forest Vegetation Simulator (FVS), a forest vegetation modelling framework that has been used extensively in the United States and more recently in Canada. In the United States 21 variants have been developed to customize the model to regional conditions. Most of these variants are based on the original FVS variant: the Prognosis Model for Stand Development (Wykoff et al. 1982), developed by the USDA Forest Service for the northern Rocky Mountain region of Idaho and western Montana, USA.

FVS variants map

FVS Variants: versions of FVS, sometimes quite different from each other in internal structure, have been developed for most forest types inthe US. Click on the map for more detail.

FVS in the Great Lakes Region

One of the variants that is not based on the Prognosis Model is the one used in the US Great Lakes region. This variant uses a growth engine adapted from the TWIGS model (The Woodsman's Ideal Growth Projection System - Miner et al. 1988) developed by the USDA Forest Service in the 1980's. This model is conceptually quite different from the variants developed elsewhere. The Prognosis and TWIGS growth engines were developed independently, in different geographic regions and in response to differently perceived needs.

The evolution of FVS

In Canada, the British Columbia Ministry of Forests has adapted the Prognosis growth engine for the Province. They have also developed a new FVS software implementation (called PrognosisBC) in metric units.

Recently, the TWIGS based growth engine from the Lake States FVS variant has been adapted for many Ontario forest conditions (called FVSOntario). This approach was used because the Lake States variant is the most proximal to the intended area of application. Whether the Prognosis approach might be more appropriate is not known, and examining this question is a goal of one of the research projects underway at Michigan Tech.

The Prognosis individual tree basal area increment sub-model (Wykoff 1990) is probably the most well-known FVS component.  Revsisions to this model to change the way climate is represented have been proposed, and another project at Michigan Tech is underway to refine this methodology.

For more information

To find out more, the first place to start is this website!  Under the research tab you can find more information on FVS research projects underway at Michigan Tech. Tools and Documents related to FVS research and development at MTU are also available, and will be added as they are finalized.

The official USDA Forest Service web site for FVS is  Many other useful links may be found on our links page.

Literature Cited

Miner, C. L., N. R. Walters and M. L. Belli (1988). A guide to the TWIGS program for the North Central United States. General Technical Report NC-125, USDA Forest Service, North Central Forest Experiment Station, St. Paul, Minnesota.

Wykoff, W.R. 1990. A basal area increment model for individual conifers in the northern Rocky Mountains. For. Sci. 36:1077-1104.

Wykoff, W.R., N.L. Crookston and A.R. Stage. 1982. User's guide to the stand prognosis model. USDA For. Serv., GTR-INT-133. 112 p.

Last Updated: September 7, 2005

Copyright 2004-05 Michigan Technological University.  All Rights Reservered.


May 2005
MTU and Ontario MNR Collaborate on Great Lakes Variant


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