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P A L E O - F I R E C L I M A T O L O G Y
Photograph: Kurt Schierenbeck
Main methods used to reconstruct fire history from tree rings
Fire scars
Tree and forest stand ages
Tree mortality dates
Ring-width growth changes
Combinations of evidence
Sequoia fire scars
Photograph: Tom Swetnam
Pinus sylvestris tree rings and fire scars, Siberia
Photograph: Tom Swetnam
Low Moderate High
Fire intensity
Extensive
Limited
Fire evidence
Low Moderate High
Fire intensity
Extensive
Limited
Fire evidence
No scars No trees
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
Spatial scales of fire history studies
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
Spatial scales of fire history studies
TreeVery fine scale, local pa!erns that determine first scar (and later scars)
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
Spatial scales of fire history studies
StandFine-scale vegetation, fuels, wind, microclimate
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
Spatial scales of fire history studies
Watershed Topographic and elevation e"ects on fire spread
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
Spatial scales of fire history studies
Regional Climate, broad-scale human land use
1ONEFIRE AMONG THE GIANTS
h!p://esp.cr.usgs.gov/data/atlas/li!le/
Photograph: Byron Hetrick
Photograph: Kai Schreiber
... public concern led to a temporary suspension of the prescribed fire program, a review by a panel of scientists, and a call for more detailed fire history studies in the groves.
“”
Swetnam et al., Fire Ecology, 2009
Photograph: Ma!hew Fern
Photograph: Tom Swetnam
Julio Betancourt Tom Swetnam
?Source: Swetnam et al., Fire Ecology, 2009
?At what frequency, seasonality, and extent did surface fires formerly burn within the Giant Forest?
Source: Swetnam et al., Fire Ecology, 2009
?At what frequency, seasonality, and extent did surface fires formerly burn within the Giant Forest?
What role did climate variations play in determining these fire regime characteristics?
Source: Swetnam et al., Fire Ecology, 2009
?Given the fire and climate history of the past 3000 years, what lessons and insights might we draw from this history as a guide to present and future fire management?
At what frequency, seasonality, and extent did surface fires formerly burn within the Giant Forest?
What role did climate variations play in determining these fire regime characteristics?
Source: Swetnam et al., Fire Ecology, 2009
Source: Tom Swetnam
Photograph: Miguel Viera
And see this ring right here, Jimmy? ...That’s another time when the old fellow
miraculously survived some big forest fire.“
”
Source: Swetnam et al., 2009
Photograph: J. Dieterich
Photograph: J. Dieterich
Photograph: Henri Grissino-Mayer
Photograph: Tom Swetnam
Tom Swetnam and Chris Baisan sampling eye socket fire scars at Big Stump, Kings Canyon NP
Photograph: Tom Swetnam
Source: Tom Swetnam
Source: Swetnam et al., Fire Ecology, 2009
Fire interval = Number of years between fire events
Source: Swetnam et al., Fire Ecology, 2009
The earliest fire date recorded by a growth release was in 181 B.C.E., and the earliest fire scar date was in 56 B.C.E. The latest fire date (recorded by a scar) was in 1915 C.E.
“”
Swetnam et al., Fire Ecology, 2009
Fire frequency = Number of fire events per 50-year period
Source: Swetnam et al., Fire Ecology, 2009
However, these distributions provide only relativistic estimates of fire free intervals (or fire frequencies) within the scales, locations, and time periods described, and not absolute estimates of area burned.
“”Swetnam et al., Fire Ecology, 2009
Source: Swetnam et al., Fire Ecology, 2009
By 1890, NM had more than 5 million sheep in 1.5 million ca!le.
Photograph: Charles Kaiser
Fire scars, other tree-ring indicators, and charcoal in wet meadow sediments from the Giant Forest and other sequoia groves show that the “normal” condition of these fire regimes is one of highly frequent surface fires.
“”
Swetnam et al., Fire Ecology, 2009
The most recent century and a half (since circa 1860 C.E.) of fire suppression by people is the most anomalous, low-fire frequency period in at least the past 3000 years.
“”
Swetnam et al., Fire Ecology, 2009
TWONORTHERN FIRES2
Photograph: Kurt Schierenbeck
Low Moderate High
Fire intensity
Extensive
Limited
Fire evidence
No scars No trees
Miron ‘Bud’ Heinselman
“Remaining virgin forest of the BWCA” Heinselman, 1973
We have long known that fire was a factor in the ecology of the Great Lakes conifer forests, but an ecosystem view of its influence was hampered by lack of knowledge of the historical role of fire in a complete functioning natural ecosystem such as the Canoe Area’s.
“
”Heinselman, Quaternary Research, 1973
280-yr red pine stand near Ramshead Lake Heinselman, 1973
Inferred area burned Heinselman, 1973
A natural fire rotation of about 100 yr prevailed in prese!lement times, but many red and white pine stands remained largely intact for 150-350 yr, and some jack pine and aspen-birch forest probably burned at intervals of 50 yr or less.
“
”Heinselman, Quaternary Research, 1973
THREEFIRE AND CLIMATE3
Very broadscale synchrony (at >104 km2 scales) is typically related to climate variability a"ecting the co-occurrence of ecological events in many places, because most ecological disturbances or processes are not capable of physically spreading over such large areas.
“
”Swetnam and Brown, Dendroclimatology, 2010
Source: Swetnam and Brown, Dendroclimatology, 2010
Cook et al., 2007, Earth Science Reviews
Source: Swetnam and Brown, Dendroclimatology, 2010
SUPERPOSEDEPOCH
ANALYSIS
Reference: Baisan and Swetnam, Canadian Journal of Forest Research, 1990
Superposed Epoch Analysis is used to illustrate the sequence of environmental changes that usually precede and follow a specific type of event.
Reference: Baisan and Swetnam, Canadian Journal of Forest Research, 1990
Reference: Baisan and Swetnam, Canadian Journal of Forest Research, 1990
drywet
FIRE
drywet
dry dry drywet
time
Source: Swetnam and Brown, Dendroclimatology, 2010
Source: Swetnam and Brown, Dendroclimatology, 2010
Source: Swetnam and Brown, Dendroclimatology, 2010
Fire year PDSI = -1.7
Source: Swetnam and Brown, Dendroclimatology, 2010
Fire year PDSI = -1.7
Fire year -1 PDSI = +0.2
Source: Swetnam and Brown, Dendroclimatology, 2010
Fire year PDSI = -1.7
Fire year -1 PDSI = +0.2
Fire year -3 PDSI = +0.5
Source: Swetnam and Brown, Dendroclimatology, 2010
Fire year PDSI = -1.7
Fire year -1 PDSI = +0.2
Fire year -3 PDSI = +0.5
Fire year +1 PDSI = -0.4
Fire year +2 PDSI = +0.4
Source: Swetnam and Betancourt, Journal of Climate, 1998
AveragePalmer DroughtSeverity Index
Source: Swetnam and Betancourt, Journal of Climate, 1998
AveragePalmer DroughtSeverity Index
Results of SEA from the Southwest regional data confirm that, on average, the larger fire years occurred during drought years and La Niña events, and that the small fire years occurred during the opposite pa!erns of pluvial years and El Niño events.
“
”Swetnam and Brown, Dendroclimatology, 2010
Interestingly, SEA also o#en shows that there were significant lagging relationships in climate/ecosystem dynamics, with fire years typically following 1–3 years of wet conditions.
“”
Swetnam and Brown, Dendroclimatology, 2010
ReadingSwetnam et al. (2009), Multi-millennial fire history of the Giant Forest, Sequoia National Park, California, USA. Fire Ecology 5, 120-150.
International Multiproxy Paleofire Database
Source: Emily Heyerdahl and Don Falk
Exercise!Use the North American Drought Atlas to explore the spatial pa!erns of droughts associated with extensive regional fires.
Source: Kurt Kipfmueller
Exercise!Due April 19
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