Fuels Planning: Science Synthesis and

Integration

Environmental Consequences Fact Sheet: 10

The Understory Response Model

United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Research Note

RMRS-RN-23-10-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

Steve Sutherland

USDA Forest Service

Rocky Mountain Research Station

Fire Sciences Laboratory

Missoula, MT

Melanie Miller

USDI Bureau of Land Management

Missoula, MT

What is the Understory Response Model?

The Understory Response Model was developed by Steve Sutherland (USDA

Forest Service) and Melanie Miller (USDI Bureau of Land Management) at the

Fire Sciences Laboratory in Missoula, Montana. It is a species-specific computer

model that qualitatively predicts change in total species biomass for grasses, forbs, and shrubs after thinning, prescribed fire, or wildfire. The model examines the effect of fuels management on plant

survivorship (the survival, growth, and colonial

growth of plants present at the site before treatment)

and reproduction (establishment and growth of plants

from stored seeds and onsite and offsite colonization).

Intended Users

The Understory Response Model was created as a planning tool to assist project

or National Environmental Policy Act (NEPA) planners in evaluating the effect

of alternative fuels treatments on understory plants.

Intended Uses

The Model predicts the effect of alternative fuels treatments or wildfire on understory plant survivorship and reproduction at 1, 5, and 10 years posttreatment.

It is left to the user to set management goals and objectives, compare alternative

fuels treatments, and determine if the predicted changes in understory vegetation are acceptable.

What the Model Does

The Model provides qualitative data on the effects of alternative fuel treatments

on understory grasses, forbs, and shrubs for 1, 5, and 10 years postfuels treatment. The output provides a listing of input values, followed by qualitative effects for the survivorship and reproduction pathway for each treatment.

Pacific Northwest

Research Station

Rocky Mountain

Research Station
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

What the Model Does Not Do

The Understory Response Model does not predict quantitative changes in biomass, competitive interactions,

or new species invasions. It should be used for comparing the effect of alternative fuels treatments or wildfire

on target species and not for cross-species comparison.

Required Inputs

Treatments to Compare

• Thinning and broadcast burning

• Thinning and pile burning

• Prescribed fire

• Wildfire

Initial Stand Conditions

• Size of treatment area

• Starting canopy cover

• Duff depth

Plant Life History Traits

• Life span

• Life form

• Shade tolerance

• Root location

• Bud location

• Vegetative reproduction

• Weediness

• Sprouting ability

• Preferred light levels

• Seed dispersal

• Seed bank

• Fire stimulated seeds

• Presence onsite or offsite

Thinning Effects

• Canopy cover after thinning

• Mineral soil exposed by thinning

• Timing of thinning and prescribed fire

Fire Effects

• Canopy cover after fire

• Fuel and duff moisture

Outputs

Survivorship Pathway

• Thinning mortality

• Fire mortality

• Nutrients

• Clonal growth

• Weed

• Canopy effect

• Shrub damage

• Survivorship sum, which is a qualitative measure

of change in plant biomass from pretreatment

conditions

Reproduction Pathway

• Stored seeds

• Onsite colonization

• Offsite colonization

• Weeds

• Mineral soil

• Canopy effect

• Reproduction sum, which is a qualitative measure

of the potential for a plant to colonize or recolonize an area after fuels reduction.

How to Obtain the Model

The Understory Response Model and other related tools

can be found at: http://forest.moscowfsl.wsu.edu/fuels/