Implications of climate change on fire and thinning prescriptions

Jessica Halofsky1, 2

Morris Johnson2

1 University of Washington, School of Forest Resources2 U. S. Forest Service, Pacific Wildland Fire Sciences

Laboratory, Seattle, WA

Climate controls ecosystem processes

• The hydrologic cycle

• Plant establishment, growth, and distribution

• Disturbance– Drought– Fire – Flooding– Insect outbreaks

Fire Behavior Triangle

Fuels

Topography Weather

Fire Behavior Triangle

Fuels

Topography Weather

Area burned – Western U.S., 1916 - 2007

Area burned – Western U.S., 1916 - 2007

Fire Suppression Fire Exclusion Fuel Accumulation

Area burned – Western U.S., 1916 - 2007

Fire Suppression Fire Exclusion Fuel Accumulation

Area burned – Western U.S., 1916 - 2007

Fire Suppression Fire Exclusion Fuel Accumulation Lots of Fire Much Less Fire Lots of Fire

Fire area burned and PDO

Cascade Mixed ecoregionCascade Mixed ecoregion

Figure courtesy of J. Littell

Years with fire area > 200,000 acres

Warm-Phase PDO Cool-Phase PDO

Idaho 15 7

Oregon 14 5

Washington 11 2

TOTAL 40 (74%) 14 (26%)

Climate Change and Fire

• Warmer and drier spring conditions =– early snowmelt– lower summer soil and

fuel moisture– longer fire seasons – increased fire

frequency and extent• Fire intensity and severity

may also increase

•Average Area Burned 1970-1979 3,000,000 ac

•Average Area Burned 1980-1989 2,900,000 ac

•Average Area Burned 1990-1999 3,200,000 ac

•Average Area Burned 2000-2007 7,100,000 ac

Trends in Area Burned

• Length of fire season• Fire intensity/severity• Number of fires• Invasive species (cheatgrass)• Time needed to suppress average wildfire• Cost of suppression• Number of structures lost• Strain on fire management resources

Recent trends also show increased:

Analysis of wildfire data since 1916 for the 11 contiguous Western states shows that for a 4°F increase that annual area burned will be 2-3 times higher.

McKenzie et al. (2004), Conservation Biology 18:890-902

How much will area burned increase with climate change?

McKenzie et al. (2004)

Wildfire area burned in Oregon with 2°C warming

McKenzie et al. (2004), Conservation Biology 18:890-902McKenzie et al. (2004)

Wildfire area burned in Washington with 2°C warming

McKenzie et al. (2004), Conservation Biology 18:890-902McKenzie et al. (2004)

Projected changes in area burned in the PNW

Littell et al. 2010

Projected changes in area burned in the PNW

Littell et al. 2010

0.5 M Ac0.8 M Ac

1.1 M Ac

2.0 M Ac

Fire Regimes Vary by Environment

Wet Dry

Warm

Cold

Agee 1993

Gradients of Fire Regime Controls

Adapted from J. Agee

Mixed Severity

Mixed Severity

Low Severity

High Severity

Weather Driven

Fuel Driven

Relative influence of climate and fuels on fire regimes in common western US ecosystems

Fuels

Climate

Boreal

Subalpine

Lodgepole pine

Ponderosa pine (PNW-IM)

Mixed evergreen

Calif. mixed conifer

Ponderosa pine (SW)

Pinyon-juniper

Oak woodland

Sagebrush

Chaparral

PNW-IM = Pacific Northwest and intermountain region of the West SW = American Southwest

Relative influence of climate and fuels on fire regimes in common western US ecosystems

Fuels

Climate

Boreal

Subalpine

Lodgepole pine

Ponderosa pine (PNW-IM)

Mixed evergreen

Calif. mixed conifer

Ponderosa pine (SW)

Pinyon-juniper

Oak woodland

Sagebrush

Chaparral

PNW-IM = Pacific Northwest and intermountain region of the West SW = American Southwest

Relative influence of climate and fuels on fire regimes in common western US ecosystems

Fuels

Climate

Boreal

Subalpine

Lodgepole pine

Ponderosa pine (PNW-IM)

Mixed evergreen

Calif. mixed conifer

Ponderosa pine (SW)

Pinyon-juniper

Oak woodland

Sagebrush

Chaparral

PNW-IM = Pacific Northwest and intermountain region of the West SW = American Southwest

Climate Change

Some energy (climate) limited forests may become water (fuel) limited forests

Littell et al. 2010

Variation in Fire Severity within a General Fire RegimePr

opor

tion

SeverityAdapted from Agee 1993

Low

Moderate

High

Low Mixed High

Initially, with more frequent extreme burning conditions?Pr

opor

tion

Low Mixed HighSeverity

Adapted from Agee 1993

Low

High

Moderate

With eventual drought- and fire-induced reductions in fuel in drier forest types?

Prop

ortio

n

SeverityAdapted from Agee 1993

Low High

Low Mixed High

Moderate

Fire Regimes and Landscape Patterns

Agee 1998

Low-Severity Fire Regime

Mixed-Severity Fire Regime

High-Severity Fire Regime

MIR

OC3

_MED

RES A2 A1B B1

HAD

CM3

CSIR

O_M

K3

percent

Percent change in biomass consumed by fire2051-2100 vs. 1951-2000

R. Neilson et al., USFS and OSU MAPSS Team, Corvallis, OR

Fire interacts with other disturbances and

vegetation/fuel conditions

The Disease Spiral

Manion 1991

McKenzie et al. 2009

Adaptation strategies for natural resource management?

Adaptation strategy #1Increase landscape diversity

Thin forest stands to create lower density, and diverse stand structures and species assemblages that reduce fire hazard and increase resilience to wildfire.

Adaptation strategy #2Increase resilience at large spatial

scales

Implement thinning and surface fuel treatments across large portions of landscapes where wildfires may occur

Orient the location of treatments to modify fire severity and fire spread

Focus the spatial scale of treatments on units of hundreds to thousands of acres

Adaptation strategy #3Maintain biological diversity

Modify genetic guidelines

Experiment with mixed species, mixed genotypes

Assist colonization, establish neo-native species

Identify species, populations, and communities that are sensitive to increased disturbance

Adaptation strategy #4Plan for post-disturbance management

Treat fire and other ecological disturbance as normal, periodic occurrences

Incorporate fire management options directly in general planning process

Adaptation strategy #5Implement early detection / rapid response

Eliminate or control exotic species

Monitor post-disturbance conditions, reduce fire-enhancing species (e.g., cheatgrass)

Adaptation strategy #6Collaborate with a variety of partners

Develop mutual plans for fire and fuels management with adjacent landowners to ensure consistency and effectiveness across large landscapes

Adaptation strategy #7Promote education and awareness about climate change

Facilitate discussion among management staff regarding the effects of a warmer climate on fire and interactions among multiple resources

Educate local residents about how a warmer climate will increase fire frequency and how fuel reduction can protect property