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Fire Regimes and Forestsof the
Klamath Mountains
Carl N. SkinnerScience Team Leader
USFS Pacific Southwest Research StationSilviculture Lab
Redding, CA
“Of the hundreds of persons who visit the Pacific slope in California every summer to
see the mountains, few see more then the immediate foreground and a haze of smoke which even the strongest glass is unable to
penetrate.”
C. Hart Merriam1898 Visit to Siskiyou CountyChief, Division of Biological Survey
From: Morford 1984
Long-term History
Fires have been an integral PROCESS
in forested ecosystems of northern California and southwestern
Oregon for millennia.
Much longer than the 3000-4000 years of current forest assemblages.
KlamathMountainsBioregion
X
XX
X
Mixed-severity Fire Regimes?
Somewhere betweenMostly Low-severity
and Mostly High-severity
Severity Patternsin the
Klamath Mts
Spatial Context
NOT Random
Environmental ControlsEnvironmental Controls
• Climate
• Substrate
• Topography
• Vegetation
• Climate
• Substrate
• Topography
• Vegetation
- Climate -
• MEDITERRANEAN• Cool/wet Winters
vegetation/fuel• Warm/dry Summer
annual fire season• Lightning• Inter-annual Variability
Environmental Influence on Fire Regimes
- Climate -
• Fire Frequency –Temperature
• Fire Extent --Moisture
Climate Variation?
- Substrate -
• Site Productivity• Ultramafics• Limestone• Fuel Breaks
-Topography-
• Topographic position• Ridge tops• Aspect• Riparian Areas
- Vegetation -- Vegetation -
• Fuel• Quantity• Spatial pattern
Tree-ring Evidence
Tree-ring Evidence of Fires
-Fire Characteristics-
• Mixed-severity fire regimes
• Generally frequent – occur at least several times in the lives of the dominant tree species.
• Generally dominated by low and moderate severityeffects.
Hayfork Study Area
Cave Junction Vicinity
Fire Suppression
Effect
LSOG StandLSOG Stand
2
3
4
5
2 3 4 5Number of 60 yr Age Classes
Fires / Age Class
Taylor & Skinner 1998
Fires and Age StructureThompson Ridge
Tree-ring Evidence of Fires
- Landscapes -
• Forests of variable structure
• Mostly more open than today
• Stands of large, old trees common in the lower slopes and on north and east facing slopes.
Fire Severity DistributionFire Severity Distribution
0%
25%
50%
75%
100%
Biscu
it 02
Dillon
94
Hayfo
rk 8
7
Thom
pson
Rid
ge
HighModerateLow
USDA Forest Service 2003Taylor & Skinner 1998Weatherspoon & Skinner 1995
Fire Severity Patterns
Fire Severity Patterns
High Complex1999
Shasta-Trinity NFs
High Complex1999
Shasta-Trinity NFs
Fire Severity DistributionThompson Ridge
North & EastSouth & West
0%
25%
50%
75%
100%
Low
er
Mid
dle
Upper
Upper
Mid
dle
Low
er
HighModerateLow
Taylor & Skinner1998Slope Position
Fire Severity PatternsFire Severity PatternsUpper SlopeUpper Slope
Greater %Greater %High SeverityHigh Severity
Mid SlopeMid SlopeIntermediateIntermediate
Lower SlopeLower SlopeGreater %Greater %
Low SeverityLow Severity
Taylor & Skinner 1998
Temperature InversionsTemperature Inversions
Topography &
Fire Regimes
Topography &
Fire Regimes
Fire OccurrenceGroups
Fires were limited by topographic features(ridgetops, streams, aspect changes, etc.)
Taylor & Skinner 2003
Topography &
Fire Regimes
Topography &
Fire Regimes
Taylor & Skinner 2003
Fire OccurrenceGroups
Fires were limited by topographic features(ridgetops, streams, aspect changes, etc.)
Reduction in Size of Forest Openings
0.01
1
100
1944 1985
Skinner 1995
Acres (log scale)
Changes in Fuel Continuity
Skinner 1995
11
2233
11
2233
Spotted Owls & FireSpotted Owls & Fire
• LSOG• North Slopes• Lower Canyons
• LSOGon North Slopes
• LSOGin Lower Canyons
Nesting
Fire
Spotted Owls & FireSpotted Owls & Fire
• Open for flying/hunting
• Woodrats• Thickets/Shrubs
• Generally open stands
• Thickets/Shrubs: edge
Foraging
Fire
Typical Patternin mixedlow-moderateseverity fire regimeswith frequent fires.
Typical patternin high severity fire regimes.
LandscapePatterns
Topography &
Fire Regimes
Topography &
Fire Regimes
Taylor & Skinner 2003
Fire OccurrenceGroups
Fires were limited by topographic features(ridgetops, streams, aspect changes, etc.)
Fire Severity PatternsFire Severity PatternsUpper SlopeUpper Slope
Greater %Greater %High SeverityHigh Severity
Mid SlopeMid SlopeIntermediateIntermediate
Lower SlopeLower SlopeGreater %Greater %
Low SeverityLow Severity
Taylor & Skinner 1998
Fire Severity Patterns
More Severe Fuels TreatmentsMore Severe Fuels Treatments
Mid SlopeIntermediateMid SlopeIntermediate
Least Severe Fuels TreatmentsLeast Severe Fuels Treatments
Taylor & Skinner 1998Taylor & Skinner 1998
Thank You!Thank You!
