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Carbon Estimations


Natural resource managers are increasingly interested in the effects of planned management activities on carbon stocks. The Forest Vegetation Simulator (FVS) is a family of forest growth simulation models that allow a user to explore how silvicultural treatments may affect growth and yield (and, therefore, carbon stocks). "Suppose" is the name for the graphical user interface for FVS.


Text files of growth and yield calculations. A variety of post-processor applications, including Windows-based "Suppose", are available to translate these text outputs into a variety of graphical displays and reports.

Developed by

Forest Management Service Center (FMSC), Fort Collins, CO; the FMSC is part of the US Forest Service Forest Management Staff


Downloadable modeling software (15-30 MB, depending on region), with a variety of optional downloadable variant files, pre-processors, post-processors, and an optional Windows-based graphical user interface


Continental United States, Alaska

Scale (range)

Stand to landscape

Potential Applications

Decision support for forest managers; useful for silviculturists, fire and fuels specialists, fire ecologists, wildlife biologists, and others interested in growth & yield, forest succession, forest carbon accumulation, fire, and other silvicultural issues.

Caveats, Restrictions

FVS requires an upfront investment of several hours to one week to learn and understand how to use the program(s), depending on one’s proficiency with modeling software in general Users may teach themselves how to use FVS using the multiple resources available on the FVS website; however, multiple regional training sessions are also offered annually, from October-April. Using FVS is like learning to play an instrument – the more one becomes familiar with the model and its inputs, the better one will be able to utilize the tool to its capacity.

Forest Vegetation Simulator (FVS)

Overview & Applicability

The Forest Vegetation Simulator (FVS) is a family of forest growth simulation models that can simulate a wide range of silvicultural treatments for most major forest tree species, forest types, and stand conditions. “Suppose” is the name for the graphical user interface for FVS. FVS is useful from a stand to a landscape level.

FVS answers questions about how forest vegetation will change in response to natural succession, disturbances, proposed management actions, and how such changes affect ecosystem values. Regional variants (20 in total) have been developed and calibrated, so that outputs are specific to particular geographic areas of the United States. In addition, supplementary add-ons, or extensions to the base variants are available to assess the effects of insects, disease, and fire. The Fire & Fuels Extension (or FFE) includes down dead wood and forest floor biomass information, and can therefore help to build a more complete picture of how carbon stocks change over time and according to succession, disturbances, and management. FVS provides a synthesis of scientific knowledge about important ecosystem components and a means for integrating the knowledge in a format useful to resource managers.

  • The basic version of FVS allows users to understand management impacts on carbon stocks assuming current/historical climate conditions.
  • The Fire & Fuels Extension for FVS links the Forest Vegetation Simulator with models of fire behavior, fire effects, fuel loading, and snag dynamics to allow for a more fire-relevant and in-depth exploration of management decisions on growth and carbon stocks.
  • The Climate Extension for FVS (Climate-FVS) simulates the effects of climate change by modifying (rather than replacing) the growth, mortality, and regeneration components found in the basic version. This allows users to access the features of the basic version of FVS, and in addition model the effects of changing climate conditions on carbon stocks. A detailed description is available in this journal article.


Since its initial development in 1973, FVS has become a system of highly integrated analytical tools. These tools are based upon a body of scientific knowledge developed from decades of natural resources research.

Inputs and outputs

At its core, FVS requires basic forest inventory and stand examination information. One can get started by only inputting data about tree species, DBH, and sampling design (to be able to accurately scale the data) but the more input data the user gives it, the more powerful and accurate the model can be. So, for example, data regarding site quality, latitude and longitude, slope/aspect, tree height and crown width are all very helpful inputs that will enable more precise outputs from FVS. A variety of data sources can be modified or translated to serve as input for FVS: a user could employ local, field-gathered forest inventory data; s/he could use data from the Forest Inventory and Analysis (FIA) program; or s/he could use data from the Natural Resources Information System (NRIS) Field Sampled Vegetation (FSVeg), which includes plot vegetation data from FIA and elsewhere.

Whichever data source is used, the input data must be processed into an FVS-friendly format, i.e., into FVS-ready database files or text files. This may be done using one of the “pre-processors” available on the FVS website. For example, FIA data is not directly FVS-ready, but there is a pre-processor that allows FIA data to be processed for use with FVS.

FVS produces output files that include growth and yield information based upon the site, input tree data, and user-specified disturbances and silvicultural treatments. A variety of post-processors can perform additional calculations and are capable of translating the FVS output into reports and/or graphical displays. Output can also be sent directly to a database. Post-processors can run within, or independent from “Suppose”, the graphical user interface of FVS.

Restrictions and limitations

FVS is a powerful tool that requires a bit of dedication to be able to learn and use. Plenty of information is available through the FVS website, or potential users can sign up for one of several regional training sessions that are held annually.

Accessing the tool and additional information

This description of FVS only skims the surface. To become a competent FVS user will take some additional investment of time and energy – the best place to get started is on the FVS website: http://www.fs.fed.us/fmsc/fvs/

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