Biology ETDs

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Chlorophyll concentration and reflectance of bark samples of Populus tremuloides Michx. growing at various elevations in the Sangre de Cristo mountain range of New Mexico indicate the appearance of greener barked trees at higher elevations is due to the reflectance characteristics of a bloom of dead periderm cells and not to increased chlorophyll concentrations. Chlorophyll concentration in aspen bark were, in fact, inversely correlated (p=.001) with altitude.

The higher concentration of chlorophyll at lower elevations is effectively masked by a white bloom which is also characteristic of exposed site trees. At higher elevations the bloom is yellow-brown and more translucent thus allowing the chlorophyll layers beneath to show through. Therefore, trees at higher elevations appear greener even though they have lower corticular chlorophyll concentrations.

The ecological significance of attitudinal variations in chlorophyll concentrations and reflectance of aspen bark is discussed.



Document Type


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Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

James Roman Gosz

Second Committee Member

Loren David Potter

Third Committee Member

Gordon Verle Johnson

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Biology Commons