3. 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
9. Spatial scales of fire history studies
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
10. Spatial scales of fire history studies
Very fine scale, local pa erns that
Tree determine first scar (and later scars)
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
11. Spatial scales of fire history studies
Fine-scale vegetation, fuels, wind,
Stand microclimate
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
12. Spatial scales of fire history studies
Topographic and elevation effects on
Watershed
fire spread
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
13. Spatial scales of fire history studies
Regional Climate, broad-scale human land use
Swetnam, T. W. and C. H. Baisan. 1996. USDA Forest Service General Technical Report RM-GTR-286.
18. “ ... 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
22. ?
At what frequency, seasonality, and extent did
surface fires formerly burn within the Giant Forest?
Source: Swetnam et al., Fire Ecology, 2009
23. ?
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
24. ?
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?
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?
Source: Swetnam et al., Fire Ecology, 2009
38. “ 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
39. Fire frequency = Number of fire events
per 50-year period
41. “ 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
45. “ 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
46. “ 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
54. “ 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
57. “ 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
61. “ Very broadscale synchrony (at >104 km 2 scales) is
typically related to climate variability affecting 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
65. SUPERPOSED
EPOCH
ANALYSIS
Reference: Baisan and Swetnam, Canadian Journal of Forest Research, 1990
66. 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
67. time
wet wet wet
dry dry dry dry dry
FIRE
Reference: Baisan and Swetnam, Canadian Journal of Forest Research, 1990
70. Fire year PDSI = -1.7
Source: Swetnam and Brown, Dendroclimatology, 2010
71. Fire year -1 PDSI = +0.2
Fire year PDSI = -1.7
Source: Swetnam and Brown, Dendroclimatology, 2010
72. Fire year -3 PDSI = +0.5
Fire year -1 PDSI = +0.2
Fire year PDSI = -1.7
Source: Swetnam and Brown, Dendroclimatology, 2010
73. Fire year -3 PDSI = +0.5
Fire year -1 PDSI = +0.2
Fire year PDSI = -1.7
Fire year +1 PDSI = -0.4
Fire year +2 PDSI = +0.4
Source: Swetnam and Brown, Dendroclimatology, 2010
74. Average
Palmer Drought
Severity Index
Source: Swetnam and Betancourt, Journal of Climate, 1998
75. Average
Palmer Drought
Severity Index
Source: Swetnam and Betancourt, Journal of Climate, 1998
76. “ 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
77. “ 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
78. Reading
Swetnam et al. (2009), Multi-millennial fire history
of the Giant Forest, Sequoia National Park,
California, USA. Fire Ecology 5, 120-150.
