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Aspen probe widens

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Las Conchas: Samples from the fallen tree are too charred

By John Severance

Officials are still working on the autopsy of the infamous aspen tree that caused the largest wildfire in New Mexico history and threatened the Los Alamos National Laboratory and Town Site.
Last month, Bob Parmenter, Dennis Trujillo, and Rebecca Oertel from the Valles Caldera, and Craig Allen, Collin Haffey, and Leanna Lucore from Bandelier, discovered the tree lying across the power line right-of-way on a ridge-top about a quarter mile west of Las Conchas.
The 75-foot tall tree, located about 13 miles west of Los Alamos, had fallen southward through a gap in the standing fir, the only trajectory that would have allowed it to snag the power line. The tree was on private land and it fell to the south and hit the power line, sparking the fire that burned more than 150,000 acres.
In an email Friday, Parmenter said they will be heading back to the infamous tree.
“We’ll be going back to find a better Ponderosa pine trunk to sample, as the one we cut was too charred on the outside (the fire burned away the outer years of the trunk, so it couldn’t tell us about local fires in the last 200 years).
“So, the story has some unfinished chapters, but we’re making progress.”
According to the report from the University of Arizona, scientists sanded the lowest (oldest) section of the aspen.
“The best estimate for the aspen pith date (when the tree started growing) at this point is 1913 (+/-5 yrs).  The reasons for the imprecise date are the following: (1) the ring boundaries are not clear throughout the piece (i.e., false and wedging or locally absent rings) and (2) the ring-width variability of much of the aspen in the Jemez is driven by factors other than rainfall (e.g., tent caterpillar outbreaks, temperature, competition) so it does not cross-date well with the precipitation sensitive conifers.
“Therefore, without other nearby aspen samples to compare with, this may be the best we can do.  The other sections of the tree have been cut and are drying. They might provide some validation of the tricky rings and a more precise pith date.”
The report stated that the Los Griegos fire history may be the closest to the location of the accused aspen.  The last fire recorded by multiple samples is 1892.  A single tree recorded fire scars in 1898 and 1925, and injuries in 1913 and 1918.
The report concluded, “So, it seems that the locally collected fire scarred piece is too old and the last fire recorded by multiple trees at LOG was over 20 years before the estimated aspen pith date.
“Based on the current evidence, the accused aspen may be too young to be confidently linked to a fire date.”