Biology ETDs

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Usnea tillandsioides, an aboreal lichen, was observed in great numbers on spruce and fir at an elevation of 11,200 feet in the Sangre de Cristo Range, New Mexico. The amount of fallen lichen material per hectare was estimated. When usnic acid was extracted from lichen thallus, it was demonstrated that the quantity of usnic acid was less in summer lichens than in fall lichens. By soaking lichens in water, it was possible to extract a small amount of usnic acid. However, an examination of rainwater did not indicate that usnic acid was being leached from lichens by rainfall. Soil and litter samples were then analyzed for usnic acid content. The small amount of usnic acid present in litter samples suggested that decomposition of usnic acid must by taking place. Soil fungi and bacteria from the study area were isolated and classified. By culturing these microorganisms in a liquid medium containing usnic acid, each organism’s ability to degrade usnic acid, each organism’s ability to degrade usnic acid was measured. The importance of soil microflora in degrading usnic acid was extrapolated from these data. Coniferous seeds were also subjected to usnic acid and compared for their ability to germinate and form roots under various concentrations. Further experimentation with young trees indicated that usnic acid may be extremely damaging when applied to roots in a concentration of 0.2 mg/ml ethyl acetate. The significance of these results is presented in view of the forest ecology.



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Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

James Roman Gosz

Second Committee Member

Gordon Verle Johnson

Third Committee Member

Clifford Smeed Crawford

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Biology Commons