|Abstract or Summary
- Using ¹³C cross polarization magic angle spinning nuclear magnetic resonance
techniques on 5 species of dead trees from the northwest (western hemlock, Douglas fir,
Sitka spruce, lodgepole pine and ponderosa pine) I tracked the lignin and cellulose content
over a 22 to 36 year period in order to determine the effects of decay fungi, if any, that is
attacking certain species of tree. I had samples from the wood of the roots, the bark on the
roots and, in some cases, the resin core of the roots. The Department of Forest Science at
Oregon State University has studied this problem by using wet chemical analysis, and
direct visual observation. Mark Harmon and Hua Chen of the Department of Forest
Science believe that white rot occurred most frequently in the lodgepole pine and
ponderosa pine and brown rot was more frequent in the Douglas-fir and Sitka spruce.
Western hemlock seemed to have both brown and white rots active.
The Douglas fir bark sample showed definite decomposition consistent with white rot
during the first 10 years. The ponderosa pine sap showed decomposition consistent with
white rot in the 10 to 22 year period. Sitka Spruce showed some decomposition consistent
with white rot in the bark from 7 to 33 years, and the western hemlock showed some
decomposition consistent with white rot in the sap in the first 10 years.
The decompositions consistent with brown rot were much easier to see in this study.
Virtually all the sap and bark samples showed decomposition consistent with brown rot at
some point. The Douglas fir was the only species, other than lodgepole pine, not to show
any decomposition consistent with brown rot in the bark of the tree, only decomposition
consistent with white rot. The Douglas fir did show a decay consistent with brown rot in
the sap for the first ten years. Ponderosa pine showed evidence of decay that brown rot
would cause for the first 10 years in the sap and the bark. The Sitka spruce species
analysis showed brown rot type decay in the bark for the first 7 years and in the sap for the
entire time studied of 33 years. The lodgepole pine was the only species to not show any
brown rot type decay in the sap or bark for the entire 22 year period studied. The western
hemlock was distinct by not showing any definitive brown rot type decay for the first 10
years, but showed massive decay consistent with brown rot in both sap and bark during the
following 26 years studied.
I used an 8 Tesla magnet and the MAS frequency was at 5 kHz. The recycle time was
1.5 seconds and the contact time was 1 ms. I generally took about 10,000 acquisitions per
sample, which added up to about 4 hours total acquisition time per sample.
Presence of these rots shows that certain species are more susceptible than others, and
also shows that local environmental conditions can contribute to rot susceptibility.