Fuels Planning: Science Synthesis and

Integration

Environmental Consequences Fact Sheet: 13

Root Disease Analyzer—Armillaria

Response Tool (ART)

United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Research Note

RMRS-RN-23-13-WWW

March 2005

Fuels planning: Science synthesis and integration, an interagency research/management

partnership to support the Ten-Year Fire Plan,

led by Russell T. Graham, RMRS, and Sarah M.

McCaffrey, NCRS.

Synthesizing

Scientific Information

for Fire and Fuels

Project Managers

Environmental Consequences

Team Leader

Elaine Kennedy Sutherland

USDA Forest Service

Rocky Mountain Research Station

Missoula, MT

Geral I. McDonald

Philip D. Tanimoto

Thomas M. Rice

David E. Hall

Jane E. Stewart

Paul J. Zambino

Jonalea R. Tonn

Ned B. Klopfenstein

Mee-Sook Kim

USDA Forest Service

Rocky Mountain Research Station

Moscow, ID

Pacific Northwest

Research Station

Rocky Mountain

Research Station

What is ART?

The Root Disease Analyzer—Armillaria Response Tool (ART)—is a Web-based

tool that estimates Armillaria root disease risk in dry forests of the Western United

States. It uses habitat types to identify sites with high- or low-risk potential for

developing Armillaria root disease, which can reduce productivity and increase

wildfire risk. ART indicates how some fire planning (fuels management) activities may exacerbate Armillaria disease within high-risk stands, and helps determine an appropriate fuels management plan for reducing future damage by

Armillaria root disease.

Resinosis (left) is a common symptom on trees infected with Armillaria root

disease. Tightly attached

mycelial fans (right) are a

definitive sign of Armillaria

root disease, and can be

found beneath the bark on

roots and lower boles of

infected trees. Photos

credit: R.C. Rippy (left) and

J.W. Hanna (right).

Armillaria Root Disease and Fuels Planning

Root rot caused by Armillaria fungi warrants special consideration before fuels

management activities are selected in Western forests. Armillaria species are widely

distributed, and their effects on disease and mortality can increase greatly after

human-caused disturbances. Not all Armillaria species decrease forest productivity. Some nonpathogenic species of Armillaria are beneficial forest decomposers. But in many environments, pathogenic Armillaria fungi cause reduced tree

growth, increased mortality, and predisposition to bark beetle attack. In addition, Armillaria root disease can increase wildfire risk by contributing to fuels

buildup and fuel ladders in affected stands.

Habitat Types, Subseries, and Armillaria Risk

Associations of plant species, known as habitat types, are strong indicators of

site conditions, which are determined by the interaction of topography, soil,

temperature, and precipitation patterns. Data from random Armillaria plots

throughout the Western United States have indicated that distribution of

Armillaria species is strongly correlated with habitat type, which combines overstory series and forest floor vegetation. Habitat types reflect combined temperature-moisture regimes. Subseries, which are groups of habitat types, can be used

as indicators of Armillaria regimes (Armillaria distribution and activity), as well
The Fuels Planning fact sheets are based on preliminary findings. Information from fact sheets will be synthesized in an upcoming publication.

Environmental Consequences Fact

Sheets

Look for fact sheet topics from the Environmental Consequences

Team including information about the effects of fire behavior and

alternative treatment strategies, Wildlife Response Model, weed responses, riparian systems, soil erosion, restoration objectives, treated

spaces, the Fire Effects Information System (FEIS), and the First

Order Fire Effects Model (FOFEM).

Fuels Planning: Synthesis and Integration

This fact sheet is one in a series being produced as part of a larger

project supported by the USDA Forest Service to synthesize new

knowledge and information relevant to fire and fuels management.

Fact sheets address topics related to stand structure, environmental

impacts, economics, and human responses to these factors. Information in the fact sheets is targeted for the dry forests of the Inland

West, but is often applicable across broad regions of the country.

For more information, please visit our Web site at:

www.fs.fed.us/fire/tech_transfer/synthesis/synthesis_index

as fire severity and fire return intervals in coniferous

forests of the Western United States.

Intended Users

• Fuels treatment planners

• Silviculturists

• Resource managers

• National Environmental Policy Act (NEPA)

planners

Intended Uses

ART can help reveal stands with site conditions that

indicate risk for developing Armillaria root disease, if

susceptible host trees are present. It is intended to help

users make predictions and evaluate impacts of alternative fuels treatments. Knowledge about the role of

fire and responses of various species in Western forests

is a good starting point for management considerations.

Each fuels-treatment option must be considered in relation to the habitat type, mix of host species, and other

interacting factors.

Required Inputs

• Stand location (Forest Service Region or National

Forest)

• Habitat type

• Fuels treatment

For effective use of ART, it is essential that stand habitat types have been correctly identified. A GIS-based

extension to ART uses landscape analysis to identify

misclassified stands and stands with differences in slope

and aspect classes that may indicate substands with different habitat types.

What the Model Does

Outputs include:

• Low or high risk for the presence of Armillaria

root disease

• Potential behaviors after fuels treatments

ART presents potential effects of fuels treatments for

high- and low-risk categories. Treatments included in

the tool are:

1. No treatment

2. Thinning

3. Prescribed burning

4. Thinning and prescribed burning

5. Wildfire

To assess the effects of fuels treatments on Armillaria

root disease, it must be determined whether Armillaria

species are likely to exist on the site. As expected, fuels

treatments will have no effect on Armillaria root disease for subseries where Armillaria root disease does

not occur. Where Armillaria can occur, the decision process is more complex and must consider tree species

present, fire regimes, and fuels treatment methods.

For More Information

The ART model and documentation are available online

at:http://forest.moscowfsl.wsu.edu/fuels/art/

ART is currently in the early developmental stage.

The habitat type for this stand is grand fir/ninebark-ninebark phase (Abies

grandis/Physocarpus malvaceus—Physocarpus malvaceus) (ABGR/

PHMA-PHMA). The Armillaria Response Tool would classify this stand

as high risk for the presence of Armillaria root disease. Armillaria root

disease causes mortality that can increase fuels buildup and risk of

wildfire. Photo credit: R. C. Rippy.