FVS Models & Event Monitor Files

Spongy Moth Event Monitor Addfiles

What is it?

The Spongy moth (formerly known as gypsy moth) Monitor is a program that simulates the effects of spongy moth within the confines of the Forest Vegetation Simulator (FVS). Individual stands are evaluated with a susceptibility index system to determine the vulnerability of the stand to the effects of spongy moth. A spongy moth outbreak is scheduled in the FVS multi-year cycle if a drawn random number is less than or equal to the estimated probability of outbreak in that multi-year cycle. If an outbreak is scheduled, spongy moth mortality is leveled against species deemed susceptible and resistant; basal area growth is increasingly reduced in susceptible species during light, medium and heavy outbreaks, whereas during a heavy outbreak, basal area growth is somewhat reduced in resistant species.

This is a strategic model that demonstrates the potential loss of timber and habitat due to spongy moth. The user can proactively reduce the stand’s susceptibility to spongy moth and the probability of a spongy moth event by scheduling appropriate management actions within FVS (see Gottschalk 1993). Due to the limitations in FVS’s growth and mortality equations, the variability normally seen in response to spongy moth defoliation cannot be adequately modeled. As such, the user is cautioned that the best use of this Event Monitor is to show relative differences in responses of stand to spongy moth rather than predicting absolute responses in individual stands. The Spongy Moth Event Monitor can be used to prioritize stands for treatment or to estimate the overall impacts to a forested landscape.

Who should use it?

The Spongy Moth 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 spread sheet programs for further user analysis.

How do I use it?

The Spongy Moth Event Monitor is an FVS Addfile, which typically have a "*.kcp" file extension. The geographically appropriate Event Monitor must be added to the simulation, after one or more stands have been selected for use within FVS. The Spongy Moth Event Monitor Users Guide included with the event monitor files describes how to use the addfile, evaluate its results, and who to contact with questions.

Which Spongy Moth Event Monitor Files do I use?

There are eight types of spongy moth keyword component (.kcp) addfiles appropriate for use with FVS, two for each of the four supported variants: Northeast (NE), Central States (CS), Lake States (LS), and Southern (SN). Users who wish to simulate the effects of spongy moth should use GM_NE_1985.kcp, GM_CS_1985.kcp, GM_LS_1985.kcp or GM_SN_1985.kcp dependent upon stand location and their preferred FVS variant. Users who wish to only track the susceptibility of stands to spongy moth should use GM_NE_SUSC.kcp, GM_CS_ SUSC.kcp, GM_LS_ SUSC.kcp or GM_SN_ SUSC.kcp, dependent upon the preferred variant.

FHAAST will create additional spongy moth event monitor files for other variants upon request.

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.

Download

Spongy Moth Event Monitor (GMem.exe, 132 KB, updated 07-18-2005)

Head shot of late instar spongy moth feeding on white oak. Photo by John Ghent.