Graduate Thesis Or Dissertation
 

¹³C-CP MAS NMR study of decomposition of five coniferous woody roots from Oregon

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  • 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.
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