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United States Department of Agriculture

FVS Models & Event Monitor Files

Spruce Beetle Risk Rating Event Monitor Addfiles

What are they?

The Spruce Beetle Risk Rating EM Addfiles are two FVS keyword component files that calculate a stand's hazard rating based on a system developed by Schmid and Frye (1976). These addfiles do not perform any stand management activities; they only schedule FVS COMPUTE statements.

The system was designed for spruce beetle (Dendroctonus rufipennis Kirby) in Engelmann spruce-subalpine fir (Picea engelmannii Parry, and Abies lasiocarpa (Hooker) Nuttall) forest type in the Central Rocky Mountains. The EM addfiles provide a numerical "risk susceptibility score" that ranks the risk of stands to attack by the spruce beetle.

hemlock woolly adelgid damage

Mortality of Engelmann spruce by spruce beetle. Photo by William M. Ciesla, Forest Health Management International.

How the Event Monitor Addfile Determines Risk

This pair of Event Monitor addfiles ranks the risk of stands to attack by spruce beetles by considering four stand attributes (or risk factors):

  • physiographic location and/or site index (SI)
  • average DBH of Engelmann spruce greater than ten inches DBH
  • stand total basal area
  • proportion of spruce in the stand

Because physiographic location information is not available to the Event Monitor, the risk rating system has been written as two separate Event Monitor addfiles: one for use with creek bottom stands (SB_haz_ck_bottom.kcp), the other for use with non-creek bottom stands (SB_haz_NON_ck_btm.kcp). It remains up to the user to assign the appropriate Event Monitor addfile to each simulated stand, depending upon whether or not the stand is located in a well-drained creek bottom.

Stands are assigned risk values of 1, 2, or 3, for each of four risk factors listed above, depending upon the stand conditions for each of the risk factors. A final risk rating score is determined from the sum of the four risk factor values. The conditions defining each risk factor value are presented in table 1, below.

Table 1. Spruce Beetle Risk Rating RISK FACTORS
Risk Factor Value Physiographiclocation / Site Index QMD of spruce>10" DBH(inches) Stand Basal Area Proportion of stand that is spruce(%)
1 Spruce on well-drained sites in creek bottoms. >16 >150 >65
2 Spruce on sites with a SI50 =52 (ft.). 12-16 100-150 50-65
3 Spruce on sites with a SI50 < 52 (ft.). < 12 < 100 < 50

Schmid and Frye (1976) group the final hazard rating numeric scores into five qualitative ratings: low, low-to-moderate, moderate, moderate-to-high, and high (table 2). The Event Monitor only reports the numerical rating. It remains up to the user to determine the qualitative rating.

Table 2. Schmid and Frye's qualitative interpretation of the numerical risk rating scores
If the total score is: The qualitative risk rating is:
4 - 5 LOW
11 - 12 HIGH

Details regarding the two Event Monitor addfiles—including discussion of site index related issues—can be found in the User's Guide included in the download package.

Download the Spruce Beetle Risk Rating EM Addfile and User's Guide

  1. The FVS Spruce Beetle Package link will download a self-extracting Zip file. You may download this .exe file anywhere on your computer.
  2. Once downloaded, double-click the .exe file to begin the extraction process.
  3. Although you may extract the files to anywhere on your computer, we recommend that you use the default extraction locations. The files will include the Spruce Beetle EM Addfiles (SB_haz_ck_bottom.kcp/SB_haz_NON_ck_btm.kcp) and the accompanying User's Guide

Event Monitor Output

Output from these Event Monitor addfiles will include the values of all variables used in calculating the hazard rating score(s) as well as the hazard rating scores themselves. Output is written to the standard FVS output table. Output may also be written to (1) a stand-alone text file via the Compute post-processor available in Suppose, or (2) to an output database via FVS’s Database Extension, or both.


Crookston, Nicholas L. 1990. User's guide to the Event Monitor: Part of Prognosis Model Version 6.

USDA Forest Service Gen. Tech. Rep. INT-275. Intermountain Res.Sta., Ogden, UT 29pp.

Schmid J.M., and R.H. Frye. 1976. Stand Ratings for spruce beetles. USDA Forest Service Res. Note RM-309. 4pp.