Presentation Transcript
Slide1: Long-term climate variation and fire in western conifer landscapes: relevance to establishing reference conditions
Grant A. Meyer
Jennifer Pierce
Department of Earth and Planetary Sciences
University of New Mexico
Slide2: 2002 fire perimeters Yellowstone:
cool-moist
lodgepole pine-mixed conifer Central Idaho:
warm-dry ponderosa pine Sacramento Mountains:
ponderosa-mixed conifer…
Slide3: Central Idaho ponderosa: presettlement regime of light surface fires,
RI 5-30 yr Yellowstone lodgepole-mixed conifer: large, severe stand-replacing fires,
RI 200-400 yr
Slide4: Rill and channel erosion
(1988 fire, 1989 storm, Yellowstone) Loss of root strength, saturation-failure
of colluvium (1989 fire,
1997 storm, Idaho) Initiation of debris flow-flood events through runoff and sediment bulking
Slide5: 1989 debris flow-dominated event, NE Yellowstone
Slide6: 1989 debris flow older fan sediments 1988 charred litter layer (burned soil surface)
Slide7: burned soil surface layer,
1870 ± 70 14C yr BP probable fire-related debris flow ALLUVIAL-FAN
STRATIGRAPHIC SECTIONS,
NE YELLOWSTONE tape in meters
Slide8: Radiocarbon-dated fire-related sedimentation events, Yellowstone
Yellowstone, Midway Geyser Basin: Yellowstone, Midway Geyser Basin 1871 1971
Slide13: Central Idaho ponderosa: presettlement regime of light surface fires, RI 5-30 yr
Slide14: Central Idaho alluvial fan records frequent (RI 33-80 yr) small fire-induced sedimentation events, 7400-6600 cal yr BP
Slide15: Small events from low-moderate severity fires, Idaho ponderosa calendar year before present (cal. yr BP)
Slide16: fire-related debris flow,
928 ± 34 14C yr BP ALLUVIAL-FAN
SECTION GJ1,
SOUTH FORK PAYETTE RIVER BASIN, IDAHO
Large debris flows from severe fires, Idaho ponderosa: Large debris flows from severe fires, Idaho ponderosa
Distribution of large (orange) vs. small fire-related events, central Idaho ponderosa (Pierce et al. 2004) : Distribution of large (orange) vs. small fire-related events, central Idaho ponderosa (Pierce et al. 2004) Medieval “warm period” or “climatic anomaly”, 900-1300 AD
Tree-ring reconstruction of drought areain the West (Cook et al., 2004): Tree-ring reconstruction of drought area in the West (Cook et al., 2004) (AD)
Slide20: Fire-related debris flows in Yellowstone lodgepole – mixed conifer Tree-ring reconstruction of drought area in the West (Cook et al., 2004) (AD)
Slide21: Frequent small events in Idaho ponderosa
Tree-ring reconstruction of drought area in the West (Cook et al., 2004) (AD)
Comparison of long-term and recent droughts in the West (Cook et al., 2004): Comparison of long-term and recent droughts in the West (Cook et al., 2004)
Sacramento Mountains study area: Sacramento Mountains study area
Slide24: Tributary basin burned in Peñasco fire, with subsequent debris flow
Slide25: Older fire-related debris flow deposit, Rio Peñasco tributary: 1670-1950 AD (??)
Alluvial fan sediments along the Rio Peñasco: Alluvial fan sediments along the Rio Peñasco
Slide28: Northern Hemisphere temperature reconstructions (Briffa and Osborn, 2002) “Medieval Warm Period” “Little Ice Age”
Slide29: constant emissions at year 2000 level emissions required to stabilize CO2 at 550 ppm = 2xCO2
Slide30: Conclusions
Fire regimes are strongly influenced by climate change on millennial timescales
Severe stand-replacing fires may be rare in ponderosa ecosystems, but are not likely outside of natural variability
Along with increased stand densities, 20th-century warming is a major factor in recent catastrophic fires
Future warming and increased drought severity are likely to to further increase the probability of catastrophic fires
Reference conditions based on post-1500 AD tree-ring records and mid-1800s historical information may not accurately reflect important current and future climatic controls