Alternative to Coring in the Works Paul Jost
August 28, 2009

WI Researchers Study Bristlecone Pine

Cutting-edge research using CT Scan imaging of rare samples of ancient
Bristlecone Pine logs was conducted by Forest and Wildlife Ecology adjunct
professor R Bruce Allison August 12.

Dr. Allison, whose research interest in nondestructive testing of living
tree wood lead him to the Bristlecone Pine National Forest in the Eastern
Sierra region of California in July, returned with two large log specimens
of a tree that came down last summer as a result of a fire at the Schulman
Grove visitor center. This specimen came from the same grove in which the
world's oldest living tree began growing over 4800 years ago!

Dendrochronologists have been studying the Bristlecone Pine for decades to
uncover the records of weather patterns and climate change stored in the
annual rings. Increment borers are drilled into the tree allowing a core
sample to be extracted showing a record of ring variations. Allison has set
as his objective the development of a nondestructive sampling of the trees'
internal structure replacing increment borers with portable x-ray computer
tomography scanning similar to those used in medical imaging. The challenge
is to create the portability to carry the imaging to the living forest. He
has assembled a cooperative cross-disciplinary team including Michael
VanLysel, Associate Professor of Medicine and Medical Physics at the
University of Wisconsin and Dr. Xiping Wang, wood engineer at the US Forest
Products Laboratory plus a visiting scholar from the Northeastern Forestry
and Engineering University of Harbin, China, Li Li.

The first step in developing an x-ray imaging tool is determining the
required resolution, contrast and energy use to view internal wood. The
Bristlecone Pine has the most densely packed annual rings at 100-200 per
inch and therefore offers the greatest challenge for imaging. The group
clustered around the viewing screen of the CT Scanner at the Wisconsin
Institute of Medical Research on this first scanning test of the log samples
gasped in amazement as the first images of the internal wood structure came
into view. The wood pith, annual rings, rays cells, embedded epicormic
branches, worm holes, resin ducts and other anatomical features were clearly
displayed. Data will be analyzed over the next couple of weeks and
additional tests conducted. It is Allison's hope within a few months he will
have determined the feasibility of developing such a device and how to

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