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United States Department of Agriculture

FVS Models & Event Monitor Files

Eastern Spruce Budworm Event Monitor

What is it?

The Eastern Spruce Budworm Event Monitor is a program that estimates the potential balsam fir mortality from spruce budworm attack within the confines of the Forest Vegetation Simulator (FVS). This file is based on the work of Batzer, et al (1980) How to rate spruce-fir vulnerability to budworm in Minnesota USDA Forest Service, North Central Forest Experiment Station, St. Paul, MN pp.

This is a strategic model that demonstrates the potential loss of balsam fir timber to ESBW. The user can proactively reduce spruce budworm hazard by scheduling appropriate management actions within FVS.

spruce budworm defoliation

Spruce budworm feeding. Photo by Joseph OBrien, USDA Forest Service.


This file was created to demonstrate how Insect & Disease functionality can be incorporated into FVS. This event monitor addfile has not been tested, evaluated or validated by Forest Health Professionals. The rationale contained herein is an attempt to accurately reflect the logic portrayed in the publication referenced below. The user is cautioned as to the accuracy of output obtained by the use of this file.

Which ESBW Event Monitor Files do I use?

The ESBW Event Monitor is actually two variant specific FVS keyword component (.kcp) addfiles. These files, ESBW_LS.kcp and ESBW_NE.kcp respectively, serve the Lake States and Northeast variants of FVS. The user is strongly urged to apply the correct Event Monitor File to the appropriate stands. This is best achieved by creating geographically homogenous FVS simulations or through creative use of FVS grouping codes.

Who should use it?

The Eastern Spruce Budworm Event Monitor is intended for use by those familiar with the proper use and execution of the Forest Vegetation Simulator. It is recommended that the user be well versed in interpretation of standard FVS output. Specific Event Monitor variables can be exported to spreadsheet programs for further user analysis.

Using the table

To estimate the potential for dead balsam fir from spruce budworm attack:

  1. Determine the basal area per acre of balsam fir in the stand.
  2. Determine the percent of the total basal area that is made up of species other than balsam fir or spruce.
  3. You will find the potential for dead balsam fir (in square feet of basal area per acre) where these values intersect on the table.
This table does not include spruce, which may be severely defoliated, but not usually killed by a spruce budworm attack.

Estimated basal area of dead balsam fir after five years of attack by the spruce budworm.
Basal area of other species (percent) Original balsam fir basal area (square feet per acre)
20 40 60 80 100 120
Dead balsam fir basal area (square feet per acre)
0% 15 35 54 73 93 112
10% 11 30 50 69 89 108
20% 7 26 46 65 84 104
30% 3 22 41 61 80 100
40% 18 37 57 76 95
50% 14 33 52 72 91
60% 9 29 48 68 87

How Do I Use it?

The Eastern Spruce Budworm Event Monitor must be added to the simulation, preferably after one or more stands have been selected for use within FVS. From the Suppose Selections window:

  1. Click the "Edit Simulation File" button.
  2. Click the "Insert from file" button.
  3. Navigate to the location where you placed the ESBW Event Monitor File. Select the geographically appropriate Event Monitor file from the Insert component from file: window.
  4. Note: Double-clicking the correct filename will automatically add the Event Monitor to the selected stand(s) in question. Single-click selection requires the user to then hit the "Open" button to add the Event Monitor to the simulation.
  5. Note that the addfile now is associated with the stand(s) in question.
  6. "Close" the Edit Simulation window.
  7. Choose the post-processor that best fits your needs and run your simulation after giving it an appropriate name.

How Do I Evaluate My Results?

The user must be familiar with the standard FVS output file. The standard FVS output file is a wealth of information about the simulation you have created and run. The user is urged to pay particular attention to the following sections of the standard FVS output: Stand Composition, Activity Summary, and Summary Statistics.

The user can get direct insight into the inner workings of the ESBW Event Monitor with the two post-processors that directly report all ESBW Event Monitor Variables:

  • Compute1- table of Compute Variables (with headers)
  • Compute2- table of Concatenated Compute Variables (comma delimited)

The Compute1 table is good for general assessment and examination of overall trends within the stand. Compute2 portrays the same information in comma-delimited format that can be readily imported into spreadsheet programs such as Microsoft Excel or database programs such as FoxPro, Dbase, or MS Access.

Variables of particular interest may be, but not limited to: E_BALOSS, P_BFKILL, BF_BA, WS_BA, BS_BA, TOTAL_BA, HOST_BA, OTHER_BA. Analysis of Event Monitor results within the spreadsheet environment is helpful as the user can sort by one or more variables (such as FVS-cycle Year). It is then relatively easy to copy values from each cycle to individual worksheets to calculate sum totals and/or averages. The graphing capability of such programs like MS Excel also far exceed the graphing capabilities of Suppose.

How do I reduce the potential loss from Spruce Budworm in my stands?

A Stands composition greatly influences its vulnerability to spruce budworm damage. Generally, the more balsam fir in the stand, the greater the potential for mortality should a spruce budworm outbreak occur. The greater the species diversity, the less potential damage to balsam fir.

Typically, sound management actions that help to reduce overall basal area of balsam fir will reduce the overall stand hazard and lessen the impact of ESBW outbreaks when and if they occur. Your Regional Entomologist can tell you ways to reduce ESBW hazard in stands.

The ESBW Event Monitor Component Addfile Download

Eastern Spruce Budworm EM Addfiles (48KB .exe)