Dr. John A. Kershaw, Jr. CF, RPF, Forest Mensurationist

“The really great forester combines technical knowledge with idealism; even though he may be mistaken in detail, he must be enough of a thinker to fathom the national needs of the future.” – Theodore S. Woolsey, Jr. (Riding the Chuck Line)

FVS Ingrowth Tool

FVS Ingrowth Tool

The Forest Vegetation Simulator Ingrowth Tool (FVS IT) was developed in the Python language and tested using the Northeast variant of FVS (FVS-NE). This tool incorporates specified ingrowth tree lists, stored in secondary tree list files, into FVS projections. It functions by retrieving information from a FVS keyword file, which is then modified to project data in a stepwise manner using user-defined time intervals. Between each time step in a simulation, FVS IT incorporates ingrowth into projections by appending ingrowth tree records to projected tree lists and compiles a new tree list for the next time step. Outputs include both appended tree lists and stand summaries from FVS so that users can conduct further analyses. The FVS IT application is useful when assessing and calibrating FVS using continuous forest inventory or permanent sample plots where periodic remeasurements include ingrowth trees.


The Files for FVS IT can be found HERE

Unzip the files into a common directory and run FVSIngrowth to use the tool

About FVS IT

See: Arseneault, Kershaw, MacCarter and MacLean. In Review. Field Note — Forest Vegetation Simulator Ingrowth Tool: Incorporating ingrowth tree lists into FVS growth projections. Northern Journal of Applied Forestry for more information.

A pdf of the submitted article is found HERE

FVS IT uses a simple dialog-driven interface to obtain required inputs.

figure 1

Buttons labeled as […] allow the user to browse using File and Directory dialogs to specify required inputs.

figure 2

Directory Dialog

File Dialog

Inputs Required:

FVS Directory – The location of the folder containing the FVS variant executable.

Keyfile Path – The location of the FVS keyword file created using the FVS Suppose interface.

Save Directory – The location of the folder where all tree list and ingrowth tree list files are stored. Output files will also be created in this folder.

FVS Variant – The variant executable found in the specified FVS Directory

Once all inputs are entered, the [Run Simulation] button is pressed to launch the keyword file modification process and run FVS. Once all projections are complete, FVS IT compiles several space-delimited files containing tree list and stand summary output from FVS for further user-specific analyses.

Ingrowth Tree Lists

These files contain ingrowth tree records formatted similar to FVS tree list files.





1 – 4

Year ingrowth record is appended to tree file


5 – 8

Plot ID


9 – 11

Tree ID


12 – 17

Tree count



Tree history


19 – 21



22 – 25

Diameter at breast height


26 – 28

DBH increment


29 – 31

Live height


32 – 34

Height to top-kill


35 – 38

Height increment



Crown ratio code


40 – 41

Damage code


42 – 43

Severity code


44 – 45

Damage code


46 – 47

Severity code


48 – 49

Damage code


50 – 51

Severity code



Tree value class



Prescription code


54 – 55

Plot slope


56 – 58

Plot aspect


59 – 61

Plot habitat type



Plot topographic position



Plot site preparation


64 – 66

Tree age

For a complete description of fields, see Dixon (2003).

In order to easily and accurately associate ingrowth files with their respective tree list files, they must be stored in the same location and bear similar filenames. Ingrowth tree lists have an additional “_ing” suffix. For example, if the stand #9 initial tree list is stored in “Stand9.fvs”, the ingrowth data should be stored in “Stand9_ing.fvs”. This naming convention, coupled with the restriction that files are located in the same directory allows FVS_IT to automatically locate any required ingrowth files.

Outputs consists of:

Stand characteristics file – Space-delimited file containing stand characteristics over time as reported by FVS.

Tree list file – Space-delimited file containing tree characteristics over time such as Species, Tree ID, DBH, Height, and Tree Count.

All files are created in directory that was identified as the “Save Directory” the user

FVS IT is provided free of charge and there is no real or implied guarantee. The stepwise projection process used by FVS IT may result in loss of accuracy in individual tree growth projections, particularly in fast growing stands. Users are strongly recommended to test the program locally before use since it was originally developed for use in the Acadian Forest.

If you discover any odd behavior, errors or bugs, please contact Justin Arseneault.