Fire Frequency in Space and Time:
Some Interesting Challenges
Ken Lertzman REM, SFU
Dan Gavin, Oregon; Doug Hallett, Queens;
Emily Heyerdahl, USFS; Geraldine Jordan, Trinity Western
“Climate controls the area-burned through changing the dynamics of
large-scale teleconnection patterns (ENSO/PDO, AO) that control the
frequency of blocking highs over the continent at varying time scales”
Fauria and Johnson (2008)
PDO
regime
shift to
warm
phase
Westerling et al. (2006) Science
Also PNA pattern:
Johnson and Wowchuck, (1993)
Skinner et al. (1999, 2002)
Trouet et al. (2006)
Fauria and Johnson (2006)
Top-Down Controls:
Climate
Middle-Scale
Controls:
Topography
Bottom-Up Controls:
Fuels, Vegetation
Top-Down Climatic
Controls:
Lead to Synchrony
across space and
time
Bottom-Up Local
Controls:
Lead to Asynchrony
across space and time
Sigmoid Curve
“U” Shaped Curve
Arbitrary Scale
Biomass, GPP
Coarse Woody Debris,
Spatial Variability,
Understory Diversity &
Productivity,
NPP
Density
Young
Mature
Old Growth
K. Lertzman, REM-471
Time Since Fire
Ancient
Space, Time, Fire, Climate
• Some definitions
• Temporal and spatial scales of data
• Tree ring-based records: example of
bottom-up controls
• Sediment charcoal records: example of
dynamic top-down controls
• Fraser Valley Fire Period: proxy for the
future?
• Conclusions/Problems
Forest Landscape – a heterogeneous
mosaic of forest stands and
non-forest ecosystems.
Stand – an area of
forest relatively
homogeneous
with respect to
key variables.
K. Lertzman, REM-471
High Severity Fire – Crown Fires
• All or most canopy
trees killed
• 60 - 1000+ year
intervals
• Boreal Forests
• Lodgepole Pine
• Some Coastal Forests
• ESSF
Low Severity Fire
• Few canopy trees killed
• 5 - 25 year intervals
• Ponderosa Pine
• Interior Douglas-fir
• Grasslands
K. Lertzman, REM-471
-
Temporal Precision: Annual/Seasonal
Spatial Precision: a few metres (GPS)
Temporal Extent: 300 – 400 years
Spatial Extent: 30 ha - 3,000 ha
Scars on a Ponderosa Pine
REM-471
Dating 8 PastK. Lertzman,
Fires,
Stein Valley, BC
Fire Frequency in High Elevation Forests
Relative Fire Incidence
Charcoal in Lake Sediments
8
Early Holocene
Xerothermic
Rainforest taxa
assembling
Variable
Glaciers FVFP‘sMWP LIA
advance
6
4
2
- Temporal Precision: 10’s – 100’s of years
- (Coast
Spatial
Precision: 10 – 100 of ha
FL
Range)
- Temporal Extent: 1000’s of years
MBC (North Cascades)
- Spatial Extent: 10 – 100 km2
12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000
P(T)
Age (calendar years BP)
Soil charcoal
D. Hallett et al. 2003
Example 1: Bottom-Up Controls?
Low severity fire regime inferred from fire scars,
Stein Valley, BC
1710
Analysis Period
Heyerdahl, Lertzman, and Karpuk 2007
63% Ponderosa Pine
Mean Fire Interval 14 yrs
75% Douglas-fir
Mean Fire Interval 24 yrs
Heyerdahl, Lertzman, and Karpuk 2007
Middle Stein study area:
Plots and links
N
r
in
e
St
ve
i
R
Data collection plots and midpoints between nearest
neighbours (links):
Scarred plot
Plots
Previous scarred plot
0
1
2 km
Fire boundary
Links
Previous fire boundary
1785
N
Scarred plot
Previous scarred plot
0
1
2 km
Fire boundary
Previous fire boundary
1786
N
Scarred plot
Previous scarred plot
0
1
2 km
Fire boundary
Previous fire boundary
1788
N
Scarred plot
Previous scarred plot
0
1
2 km
Fire boundary
Previous fire boundary
1831
N
Scarred plot
Previous scarred plot
0
1
2 km
Fire boundary
Previous fire boundary
Fire and Boundary Frequencies
Jordan, Fortin, and Lertzman
Boundaries Which are
Significantly Persistent
Jordan, Fortin, and Lertzman
Incidence of Low Severity Fires:
Middle Stein 1785-1937
1930
1920
1910
1900
1890
1880
1870
1860
1850
1840
1830
1820
1810
1800
1790
1
0.8
0.6
0.4
0.2
PDO
% scarred
Jordan et al.
Example 2: Top-Down Controls?
High severity fire regime inferred from lake
sediment charcoal, Coast Range and Kootenays
Climatic driven synchrony across lakes/watersheds?
• Two lakes in the Coast Range, MH
• Two lakes in the E. Kootenays. ESSF
Bridge River tephra
Frozen Lake Plant Macrofossils
Homogenous Forest / Fuel Type for Last 5ka
Years but Variable Fire Frequency
Test for synchrony at multiple temporal scales:
univariate appication of Ripley’s K-function
Example:
Two simulated sites
with fire episodes that
occur within 50 years
of each other.
95% confidence envelope
K-function shows
significant synchrony in
windows up to 150
years.
Gavin et al. (2006) Ecology
Test for synchrony of events across temporal scales: Ripley’s K-function
Frozen and Mt. Barr Cirque lakes, Coast Range
(Overlapping records from 0-7000 cal years BP)
Hallett et al., in prep.
Synchrony Analysis: All Four Sites at 50 degrees N
(Overlapping Portion 0-5000 cal yrs BP)
Hallett et al., in prep.
Mt Barr
Soil
Cirque
Charcoal
Delta C14 Residuals – Frozen
0.2 0.4 0.6
0.8 1 1.2 AMS Ages
0.01 CHAR
0.1
1
Solar Sunspot Minima 0Lake
CHAR
500
1000
Age (calendar years BP)
1500
Maunder
Sporer
Wolf
Oort
Roman
2000
2500
3000
3500
Temp
Proxy
10
0
LIA
500
MWP
1000
1500
RWP
FVFP
Greek
2000
2500
Homeric
3000
Egyptian
3500
4000
4500
5000
5500
4000
4500
Noachan
5000
Sumarian
5500
6000
6000
6500
6500
7000
7500
7000
Jericho
7500
8000
8000
8500
8500
9000
9000
9500
9500
10000
10500
10000
10500
11000
11000
11500
12000
a
20
b
10
Quiet Sun
0
­10
­20
Active Sun
­30
d
c
0 0.1 0.2 0.3 0.4 0.5 0.6
P(T)
11500
e
­37 ­36.5 ­36 ­35.5 ­35 ­34.5 ­34 ­33.5 ­33
Cold
Warm
12000
Age (calendar years BP)
0
GISP
Core 18O
Synchrony test of century-scale solar
maxima from 14C residual data and fire
episode dates at 50 degrees N
Synchrony across
many time scales
Example 3: Fraser Valley Fire Period:
-- a model for the future?
Fire Frequency in High Elevation Forests
Relative Fire Incidence
Charcoal in Lake Sediments
8
Early Holocene
Xerothermic
Rainforest taxa
assembling
Variable
Glaciers FVFP MWP LIA
advance
6
4
2
FL (Coast Range)
MBC (North Cascades)
12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000
P(T)
Age (calendar years BP)
Soil charcoal
D. Hallett et al. 2003
Fraser Valley Fire Period
• ~ 1,200 – 2,400 BP: more fire than any other time
in the last 5,000 years.
• Mountain Hemlock forests are wet, snow
dominated - little modern evidence of fire.
• Well understood meteorological correlates of
fire weather in MH – prolonged summer drought,
blocking high pressure ridge.
• These conditions are driven by regional to
continental scale atmospheric processes.
• Fire in wet, high elevation forests is a sensitive
indicator of regional drought.
Fire Incidence
Fraser Valley Fire
Period
8
MBC
6
4
Lake Sediment Records
FL
2
0.6
Soil Charcoal Records
P(T)
0.4
Marpole Sites
0.2
0
500 1000 1500 2000 2500 3000
Age (calendar years BP)
Lepofsky et al. 2005
Some Things That Need Attention
• Evidence for both top-down and bottom-up
controls on fire.
• Inference from charcoal records useful but
still challenging. Esp link to climate drivers.
• Changing interaction of top-down and
bottom-up control over last 5 k yrs.
• Management responses depend on
bottom-up control.
• FVFP and 2003 “Firestorm” –
a good model for the future?
• Translation of historical records to
future risk scenarios?