Close up of fire scars recorded in tree growth. Photo by Tom Swetnam
- In the past, fires often burned with low intensity
- Miller, C. 2010. Review of "Light Burning Versus Forest Management in Northern California." Journal of Forestry 108(1):45-46: This 2010 Journal of Forestry article describes wildland fire back in the early 1900s.
- Wounded trees, didn't kill them
- Those fire wounds can be dated to the year
- Surviving trees are a legacies of past fire occurrence
Ponderosa pine showing many fire-scars in a large catface. Photo by Henri Grissino-Mayer.
- These fire scars are dated to the exact years of the fires that made them by a process called crossdating:
- Matching patterns of wide versus narrow rings across many tree samples
- Often done by skeleton plotting the ring growth onto graph paper
Cross section showing many fire-scars (white arrows). Photo by Chris Baisan.
- Try skeleton plotting for yourself on the Internet
- Graphically represent ring-growth variation
- Match sample marks with those from a master chronology
Example crossdating of sample graph (top) with master graph (bottom). Image by Paul Sheppard.
- Tree-ring fire sites of the Southwest often have several multiple-scarred trees
Example fire graph for Bandelier National Monument, New Mexico. Image by Tom Swetnam.
Laboratory of Tree-Ring Research, University of Arizona
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Comments to Paul Sheppard: sheppard @ ltrr.arizona.edu
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Revised April, 2012