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Fire History from Tree Rings. Justification: Wildfires in Montana and Idaho …. Justification: Wildfires in Florida and Georgia …. Justification: Wildfires in California …. Justification: Wildfires in Arizona …. Justification: Wildfires in Arizona ….
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The fire-scar record from tree rings. ponderosa pine, El Malpais National Monument, New Mexico Southwestern white pine and ponderosa pine, Mt. Graham, Arizona
The fire-scar record from tree rings. Giant sequoia stump, Sequoia National Park, California
The fire-scar record from tree rings. Table Mountain pine snag, Brush Mountain, Virginia
The fire-scar record from tree rings. Catface on Table Mountain pine log, Reddish Knob, Virginia
The fire-scar record from tree rings. Fire scars on freshly-cut Table Mountain pine, Brush Mountain, Virginia
The fire-scar record from tree rings. Fire scars on ponderosa pine, El Malpais National Monument, New Mexico
The fire-scar record from tree rings. Fire scars on sugar pine, Sequoia National Park, California
The fire-scar record from tree rings. Fire scars on giant sequoia, Sequoia National Park, California
Seasonality of past fires from tree rings. Fire scar on southwestern white pine, Mt. Graham, Arizona
Seasonality of past fires from tree rings. Detail of fire scar on ponderosa pine, El Malpais National Monument, New Mexico
Fire regimes: • Fire frequency: how often • Mean Fire Return Interval, Weibull Median Probability Interval • Fire seasonality: when fires occur throughout the year • Early season versus late season • Fire severity: effects on forests • Age structure, stand composition, stand structure • Fire extent: spatial aspects • Patchy fires versus landscape level fires • Fire variability: changes in fire over time and space • Climatic or human-driven?
Each line = 1 tree Sample IDs Dash lines = non-recorder years Begin/end symbology Each tic = fire scar Solid lines = recorder years Composite axis Interpreting Fire History Charts Years on x-axis Period of Reliability: 1896 to 1944
Spatial Temporal
Stand age and composition: • Core all species in your study area • Core all trees in your study area • Record tree and stand information • Provides information on effects of fire in forests = severity • Were fires low-severity or high-severity? • Was this a mixed-severity fire regime?
Cohort establishment, with surviving trees, then little fire for 20 years = moderate severity fire in 1853 Cohort establishment, with surviving trees = moderate severity fire in 1926 Brush Mountain Fire History Period of Reliability: 1758–1934 All-scarred class: MEI: 3 yrs; LEI: 1 yr; UEI: 8 yrs 10%-scarred class: MEI: 8 yrs; LEI: 2 yrs; UEI: 19 yrs 90% DE fires, 10% MLA fires
Cohort establishment, with surviving trees, after 1887-1890 complex of fires, 1890 = moderate severity? Cohort establishment, with surviving trees, after 1926 fire = moderate severity fire Griffith Knob Fire History Period of Reliability: 1810–1934 All-scarred class: MEI: 2 yrs; LEI: 1 yr; UEI: 4 yrs 10%-scarred class: MEI: 4 yrs; LEI: 1 yr; UEI: 12 yrs 72% DE fires, 28% MLA fires
Analyzing the Climate/Wildfire Relationship: • Done using Superposed Epoch Analysis • Originally developed to study the preconditioning controls of natural events. Examples? • Takes climate prior to, during, and after fire events, averages them together. • Where does climate information come from before climate records were kept?
