Implications of Climate Change on Fire and Thinning

download report

Transcript Implications of Climate Change on Fire and Thinning

Implications of climate change on
fire and thinning prescriptions
Jessica Halofsky1, 2
Morris Johnson2
1 University
of Washington, School of Forest Resources
2 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
Weather
Topography
Fuels
Fire Behavior Triangle
Weather
Topography
Fuels
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
Lots of Fire
Fire Exclusion
Much Less Fire
Fuel Accumulation
Lots of Fire
Fire area burned and PDO
Cascade 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
40 (74%)
14 (26%)
TOTAL
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
Trends in Area Burned
•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
Recent trends also show increased:
• 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
How much will area burned
increase with climate change?
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)
McKenzie et al. (2004), Conservation Biology 18:890-902
Wildfire area burned in Oregon with 2°C warming
McKenzie
McKenzie et al. (2004), Conservation Biology 18:890-902
et al. (2004)
Wildfire area burned in Washington with 2°C
warming
McKenzie
McKenzie et al. (2004), Conservation Biology 18:890-902
et al. (2004)
Projected changes in area burned in
the PNW
Littell et al. 2010
Projected changes in area burned in
the PNW
2.0 M Ac
1.1 M Ac
0.8 M Ac
0.5 M Ac
Littell et al. 2010
Fire Regimes Vary by Environment
Warm
Cold
Wet
Dry
Agee 1993
Gradients of Fire Regime Controls
Mixed Severity
High Severity
Weather Driven
Mixed Severity
Fuel Driven
Low Severity
Adapted from J. Agee
Climate
Relative influence of climate and fuels on fire
regimes in common western US ecosystems
Boreal
Subalpine
Lodgepole pine
Ponderosa pine (PNW-IM)
Mixed evergreen
Calif. mixed conifer
Ponderosa pine (SW)
Pinyon-juniper
Oak woodland
Sagebrush
Chaparral
Fuels
PNW-IM = Pacific Northwest and intermountain region of the West SW =
American Southwest
Climate
Relative influence of climate and fuels on fire
regimes in common western US ecosystems
Boreal
Subalpine
Lodgepole pine
Ponderosa pine (PNW-IM)
Mixed evergreen
Calif. mixed conifer
Ponderosa pine (SW)
Pinyon-juniper
Oak woodland
Sagebrush
Chaparral
Fuels
PNW-IM = Pacific Northwest and intermountain region of the West SW =
American Southwest
Climate
Relative influence of climate and fuels on fire
regimes in common western US ecosystems
Boreal
Subalpine
Lodgepole pine
Ponderosa pine (PNW-IM)
Mixed evergreen
Calif. mixed conifer
Ponderosa pine (SW)
Climate Change Pinyon-juniper
Oak woodland
Sagebrush
Chaparral
Fuels
PNW-IM = Pacific Northwest and intermountain region of the West SW =
American Southwest
Some energy (climate) limited forests may
become water (fuel) limited forests
Littell et
al. 2010
Variation in Fire Severity within a
General Fire Regime
Low
High
Proportion
Moderate
Low
Mixed
High
Severity
Adapted from Agee 1993
Initially, with more frequent extreme
burning conditions?
Proportion
High
Low
Moderate
Low
Mixed
High
Severity
Adapted from Agee 1993
With eventual drought- and fire-induced
reductions in fuel in drier forest types?
Proportion
Low
High
Moderate
Low
Mixed
High
Severity
Adapted from Agee 1993
Fire Regimes and Landscape Patterns
Low-Severity
Fire Regime
Mixed-Severity
Fire Regime
High-Severity
Fire Regime
Agee 1998
HADCM3 MIROC3_MEDRES
A1B
B1
CSIRO_MK3
A2
percent
Percent change in biomass consumed by fire
2051-2100 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 #1
Increase 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 #2
Increase 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 #3
Maintain 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 #4
Plan 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 #5
Implement early detection / rapid response
Eliminate or control exotic species
Monitor post-disturbance conditions, reduce fireenhancing species (e.g., cheatgrass)
Adaptation strategy #6
Collaborate 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 #7
Promote 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