Post on 27-Dec-2015
Fire – Climate Relations in the Western Sierra Nevada
Tom Swetnam & Chris Baisan
Colony Mill, Giant Forest
Tree sampled for fire history in 1992Open pine stand
Giant Forest plots
Vegetation, species composition plot data:
Compare pre-settlement compositionestimates with current stand composition.
Relate pre (and post) settlement compositionwith fire regime characteristics among and betweenplots, sites, and transects.
High variability in forest composition between plots
Estimates of b.a. increase from pre-settlement conditionvaried from 0 to 100%. Average increase ~50%.
Giant sequoia fire record in the Circle Meadow areanow extended back prior to ~600BC with some replication.
CEMO (0.15%)
CADE (42.46%)
PIPO (22.69%)PSME (2.48%)
QUCH (12.38%)QUKE (19.84%)
HEL Post83m2/ha
CEMO (0.25%)CADE (15.32%)
PIPO (27.77%)
PSME (2.25%)QUCH (20.90%)
QUKE (33.50%)
HEL Pre49.1m2/ha
Helispot fire history site
Elevation 1350m MFI ~6yrs
Plot species composition
-1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400
CCW 01
CCW 02
CCW 03
CCW 04
CCW 05
LIN 01
CM N 07
CM C 08
CM C 03
G ia nt Fo re st fire -sc a rre d tre e s
1
3
4
1. East Cascades, 2 watersheds, 723 trees, Everett et al. 1999, For. Ecol. & Manage., In press.
2. Blue Mountains, 4 watersheds, 628 trees, Heyerdahl 1998 PhD diss., Univ. Wash.
3. West Slope Sierra Nevada, 4 elevational transects, 49 sites, 446 trees, Swetnam & Baisan, In Press.
4. Southwestern US, 63 sites, 1,215 trees, Swetnam and Baisan 1996, USFS RM-GTR-286:11-32.
2
Four Fire-Scar Networks in Western U.S
Paleo-Fire History Databases – in construction
A. L. Westerling, T. J. Brown, A. Gershunov, D. R. Cayan, and M. D. Dettinger. Long lead statistical forecasts of area burned in western U.S. wildfires by ecosystem province. International Journal of Wildland Fire 11:257-266. 2002
Year
1860 1880 1900 1920 1940 1960 1980-2
0
2
4
6
1700 1720 1740 1760 1780 1800 1820 1840
Sta
ndar
d D
evia
tion
Uni
ts
-2
0
2
4
6 12.3
8.2Observed AreaBurned
Statistical Reconstructionof Area Burned
Fire-Scar Reconstructionof Area Burned
Composite fire scar chronologies from 10 forest stands
In the Jemez Mountains, New Mexico
Fire-scar chronology from Santa Catalina Mountains, Arizona
Fire-scar chronology from Gila Wilderness, in Southwestern New Mexico.
Swetnam and Baisan. In press. Fire and climate history in the Sierra Nevada, California and Southwestern US, Veblen et al., Fire and Climate in the Western Americas, Springer-Verlag, Ecol. Studies Series.
Fire-scar chronology from Sierra San Pedro Martir
from Stephens, Skinner and Gill, in review.
Crown King, AZ August 19, 2002; Joel McMillan
Dead and dying trees from a combination of drought stress and bark beetle attack. Area affected is now > 500,000 acres.
This may become one the largest bark beetle outbreaks in recorded history in North America.Data from USDA FS Forest Health Protection, Arizona Zone, Entomology & Pathology group.