Revised R1 forest insect hazard rating system user guide for use with inventory data stored in FSVeg and/or analyzed with the forest vegetation simulator

2011·3.9 MB·English

by  Randall, Carol Bell

Historic, Archive Document
Do not assume content reflects current
scientific knowledge, policies, or practices.

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Report 11-06 September 2011
Revised R1 Forest Insect Hazard Rating System User Guide for use with Inventory Data
Stored in FSVeg and/or Analyzed with the Forest Vegetation Simulator
Reserve
aSB761 Carol Randall’, Brytten Steed*, Renate Bush*
.R362
USDA Forest Service Region 1
2011
‘Entomologist, Forest Health Protection, Coeur d’Alene, ID
“Entomologist, Forest Health Protection, Missoula MT
*Regional Inventory Specialist, Renewable Resource Management, Miss oula, MT
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Introduction
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Forest insects and diseases are important management or disturbances; all’stand_exam,
disturbance factors in forest ecosystems. FIA, and intensified grid inventory data™
Insect and disease activity may dramatically which reside in FS Veg have these hazard
alter the structure, composition, and age class ratings calculated during the post-load
distribution of forested stands and may process and stored in FS Veg tables; and these
interfere with a manager’s ability to achieve ratings are available in the Rl Summary
established objectives. The purpose of the Database Analysis tools. This document
Forest Health Protection (FHP) division of discusses forest insect hazard ratings, how
State and Private Forestry is to assist land they are derived, and how they may be used
managers by identifying areas where insects to assist land managers with planning.
and diseases may impact resource values.
FHP personnel work with resource managers Since the original publication of this report,
to devise responses that minimize the impacts (Randall and Bush 2010) modifications were
of these agents of change. made to the mountain pine beetle in
lodgepole pine hazard rating logic, and a
As part of Region |’s Integrated Restoration combined host pine beetle hazard rating was
and Protection Strategy, FHP entomologists developed.
devised bark beetle and defoliator hazard
ratings for inventory data, such as from stand Hazard Ratings
exams and Forest Inventory and Analysis
(FIA) plots. These hazard ratings are Forest insects require three things to cause
available to assist land managers in three significant impact to resource values:
ways: they are keyword files that can be used susceptible hosts; insect populations; and
with the Forest Vegetation Simulator (FVS) favorable weather conditions. Hazard rating
to determine current hazard and model systems measure the susceptibility of forested
areas to a particular insect by evaluating the
hazards over time, with or without

amount of susceptible host. High and g c 1 7 R(Ea)C T Hazard Rating Maps
moderate hazard forested areas are more
likely to experience significant mortality if The integration of database and geographic
insect populations are present and the information system (GIS) software enables
weather is favorable. mapping of forested areas by their insect
and/or disease hazard rating. Hazard maps
enable managers to identify concentrations of
Data Considerations high- and moderate-hazard areas across a
landscape.
When using hazard ratings in a landscape
level analysis, it is assumed that available Large, contiguous forested areas of high
data are a representative sample of landscape insect hazard promote epidemic forest insect
conditions. A spatially balanced inventory populations by providing large areas of
across the geographic area of interest can be quality food. When high-hazard areas are
used to derive estimates of hazard, however, small and intermixed with low-hazard areas,
small forested areas, or areas with unique forest insect populations are not as likely to
characteristics, may not be represented or grow and cause significant resource impacts.
have insufficient data for analysis. Users Low-hazard areas have host species for a
should carefully evaluate available data for a particular insect, but the host is not of high
particular analysis area to insure that a enough quality and/or in large enough
representative sample of current forest quantity to allow forest insect populations to
conditions exists. Hazard ratings calculated build substantially. Forest insects may still
for a sampled area assumes that forest cause significant mortality in the host
conditions in the sample area are components of low-hazard forested areas in a
homogeneous; if excessive variability in any landscape, but losses will be lower than in a
of the parameters used to calculate hazard landscape where high-hazard forested areas
ratings occurs within the sampled area, the occur across a number of contiguous acres.
hazard rating may not accurately reflect the
hazard. If that is the case, further
Stratification of the geographic area of Appropriate Use of Hazard Maps
interest into various dominance types, size
classes, and densities may be needed. Spatial depictions of hazard are powerful
tools for managers and planners at the broad-
Hazard ratings applied to stand exams will (Regional assessments), mid- (Forest
accurately reflect the stand at time of assessment), and project-levels. Such maps
inventory. It is important to consider the age help managers identify areas that have the
of the data when interpreting hazard. Many highest probability of significant forest insect
stand characteristics used to calculate hazard activity. Although hazard ratings do not
may have changed since the time of the predict when insects will damage resources,
exam. If data needs to be “modeled” to experience has shown that forest insects are
current condition, then FVS, and the most likely to occur in high hazard areas.
associated hazard rating keyword files, Hazard ratings address the quality and
should be used to model hazard to a quantity of food available, but do not address
contemporary inventory date. As always, it insect populations. Therefore, additional
is prudent to ground check results. information is necessary to assess risk and
predict loss.
Keep in mind the methods used to develop a Current insect activity is the magnitude of an
hazard map. Many times the accuracy of the insect population affecting a forested area as
data is unknown. This does not mean that determined by the number of currently
the maps are not useful. If developed infested trees and their proximity to the stand
correctly, using recent spatial and tabular being assessed.
data, they can provide information about
areas that are most susceptible to forest Insect activity is a dynamic variable and may
insect outbreaks. Furthermore, due to change quite suddenly due to factors such as
stand/polygon heterogeneity, not every tree adverse or favorable weather conditions, or
or plot within a high hazard polygon may be immigration and emigration of insects. For
susceptible to the insect pest. this reason insect activity should be reviewed
every year or two.
Understanding relationships of dominance
type, size class, and canopy cover to various
forest insect hazard ratings assists with Ways to Alter Hazard: Management
developing forest insect hazard maps. Tools Considerations
have been developed by the R1 vegetation
analysis team to understand the relationships Hazard can be altered through silvicultural
of vegetation classification attributes used in practices that break up large, homogeneous
R1 (Barber et al. 2010) to the resulting blocks of susceptible forest that can host
hazard ratings. These relationships can then major insect and disease populations.
be applied to existing vegetation layers such Specific silvicultural practices to reduce
as R1-VMap, FS Veg Spatial, or a hybrid of hazard vary with the insect involved.
the two. Furthermore, other spatial Appropriate practices can be developed for
information such as elevation, potential specific land areas by various resource
natural vegetation, etc. can be integrated specialists, including entomologists and
when developing these coverages. forest pathologists from FHP.
By using FVS and associated keywords for
Project Planning hazard ratings, various silvicultural
prescriptions can be evaluated. Immediate
A hazard map is the easiest way for managers and long-term effects for various
to quickly identify areas with the highest management scenarios can be compared for
likelihood of significant forest insect activity. how they affect hazard over time.
More information is needed to plan projects.
At the project level the assumption that
stands are homogeneous may no longer be Conclusion
appropriate. Additional information from a
variety of sources, including recent walk- The use of landscape hazard rating maps for
throughs, aerial photographs, insect aerial forest insects will assist managers in
detection surveys and model runs (Forest determining the potential for these
Insect and Disease Tally System (FINDIT) disturbance agents to interfere with a
(Bentz 2000) should be gathered to help manager’s ability to reach established
determine which areas are most critical for objectives. By identifying high hazard areas
treatment. The manager should also consider prior to insect outbreaks, managers have an
the current level of insect activity in the area. opportunity to reduce hazard through
silvicultural prescriptions, including stand, prior to significant insect activity,
prescribed fire, or to determine if action is allow managers to be proactive in addressing
warranted. Tools which look at hazard, from insect dynamics by altering hazard conditions
landscape-level hazard maps to hazard of a instead of reacting to insect activity.
References
Barber, J., Berglund, D., Bush, R. 2010. The Bentz, B. 2000. Forest Insect and Disease
Region | existing vegetation classification Tally System (FINDIT) user manual. Gen. ~
system and its relationship to inventory data Tech. Rep. RMRS-GTR-49. Ogden, UT: U.S.
and the Region | existing vegetation map Department of Agriculture, Forest Service,
products. Vegetation, Classification, Rocky Mountain Research Station. 12 p.
Inventory, and Analysis Report # 10-08 6.0.
Missoula, MT: U.S. Department of Randall, C., Bush, R. 2010. R1 forest insect
Agriculture, Forest Service, Northern Region. hazard rating system user guide for use with
30 p. inventory data stored in FSVeg and/or Veg
Simulator. FHP Report 10-05. Missoula, MT:
U.S. Department of Agriculture, Forest
Service, Northern Region. 26 p.
Insect Hazard Rating Systems Available to Region 1
The hazard criteria for the following insects
Carol Randall and Lee Pederson, Rl FHP
Staff, formulated the following hazard rating and host combinations are in this document:
systems based on research cited in this @ spruce beetle (Dendroctonus
document. Researchers identified site and rufipennis);
stand characteristics associated with areas @ Douglas fir beetle (Dendroctonus
which experienced high levels of activity by pseudotsugae);
forest pests. Hazard ratings are calculated by e mountain pine beetle (Dendroctonus
looking at a combination of site and stand ponderosae) and western pine beetle
characteristics and assigning a relative index (Dendroctonus brevicomis) in
value in terms of susceptibility to the pest. ponderosa pine;
By multiplying the index values, a composite ® mountain pine beetle (Dendroctonus
index is calculated, and the composite index ponderosae) in western white pine
is assigned a hazard rating. In the subsequent ® mountain pine beetle (Dendroctonus
rating system descriptions for the individual ponderosae) in lodgepole pine
insects the following formula is used. e mountain pine beetle (Dendroctonus
ponderosae) in whitebark pine/
Calculated Value = Criteria A rating * limber pine;
Criteria B rating * Criteria C rating e western spruce budworm
(Choristoneura occidentalis) and
Each hazard rating system was translated into
Douglas-fir tussock moth (Orygia
a Forest Vegetation Simulator (FVS) event
pseudotsugae) in Douglas fir and
monitor keyword set which calculates hazard
true firs
using the original criteria in the published
® combined host pine beetle
hazard rating system then summarizes hazard
(Dendroctonus and Ips species)
into | of 4 possible classes:
Please note QMD = quadratic mean diameter,
OC O=No Host Present in Survey or
BA = basal area, DBH = diameter breast
Summary Data
height. All metrics are in English units.
O Lor 1 = Low Hazard
XO Mor 2= Moderate Hazard
O Hor3= High Hazard.
See the Appendix for the keyword sets.
These summary ratings (0, L, M, H) are
displayed in FSVeg for R1 data, available in
the Rl Summary Database analysis tool, and
may be output by FVS.
Spruce Beetle
Spruce beetle outbreaks cause extensive tree populations reach high levels, more relatively
mortality and modify stand structure by healthy trees are attacked.
reducing the average spruce tree diameter,
height, and stand density. Residual trees are In mature stands, larger diameter (> 18"
often slow-growing small and intermediate- DBH) trees usually are attacked first. If an
sized trees which eventually become infestation persists in a stand, smaller
dominant. In the Rocky Mountain West, diameter trees may be attacked.
Engelmann spruce (PIEN, ES) is the species
most often impacted. In the Rocky Mountain area, susceptibility of
a stand to spruce beetle attack is based on the
physiographic location, tree diameter, basal
area, and percentage of Engelmann spruce in
Stand Conditions Conducive To
the canopy. Engelmann spruce stands are
Infestations
highly susceptible if they grow on well-
Endemic spruce beetle populations usually drained sites in creek bottoms, have an
live in wind-thrown trees. When populations average DBH of 16 inches or more, have a
increase to high levels in downed trees, BA greater than 150 square feet per acre, and
beetles may attack susceptible, large- have more than 65 percent spruce in the |
diameter standing trees. Most outbreaks canopy. Since stand physiographic location
originate in wind-thrown trees. Once beetle is not captured in inventory data, it was
omitted in the hazard calculation but could be
added when generating a hazard map.
Hazard Criteria for Spruce Beetle
Low (.5) Moderate (2)
QMD for eee spruce >10 12” < QMD < 16”
| BBA for all species <100ft/ac |1 00<BA<150 ft/ac | 3150 fi2/ac
% of
total BA that is Engelmann spruce
>10” DBH SG 50% < % BA < 65% >65%
Directly Calculated Hazard Values Hazard Rating Multiplicative Index
Calculated Values Hazard Rating
Extremely Low Lo OE
>18
Interpreting Hazard
High hazard stands are those in which large populations may not be as active. Low-
amounts of spruce mortality can be expected hazard stands may have spruce, but are either
once a spruce beetle outbreak occurs. not of high enough quality or in large enough
Moderate and low hazard stands may quantity to allow beetle populations to
experience less beetle-caused mortality; but remain at high levels. Spruce beetle may still
individual large, old spruce might still be cause significant mortality in the spruce
killed. When high-hazard stands are component of low-hazard stands in a
intermixed with low-hazard stands, beetle landscape, but losses will be lower than in a
landscape where high-hazard stands are
clustered.
References
Schmid, J.M., Frye, R.H. 1976. Stand
Holsten, E.H., Their, R.W., Munson, A. S., ratings for spruce beetles. Res. Note RM-
Gibson, K.E. 1999. The spruce beetle. Forest 309. Fort Collins, CO: U.S. Department of
Insect and Disease Leaflet 127. Washington,
Agriculture, Forest Service, Rocky Mountain
DC: U.S. Department of Agriculture, Forest Forest and Range Experiment Station. 4 p.
Service. 12 p.
Munson, S. 2000. Personal communication. Steele, R., Williams, R.E., Weatherby, J.C.,
USDA Forest Service, Forest Health Reinhardt, E.D., Hoffman, J.T., Their, R.W.
Protection Group Leader, Ogden Field 1996. Standard hazard rating for central
Office, Ogden, UT. Idaho forests. Gen. Tech. Rep. INT-GTR-
332. Ogden, UT: U.S. Department of
Randall, C., Tensmeyer, G. 1999. Douglas fir Agriculture, Forest Service, Intermountain
beetle hazard rating system using the Oracle Research Station. 18 p.
database and the Forest Service IBM
platform. Forest Health Protection Report 99-
6. Missoula, MT: U.S. Department of
Agriculture, Forest Service, Northern Region.
by