geog3839.17, paleo-fire climatology

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