The purpose of this study was to analyze the effects of light, temperature and moisture on the ratio of alga to fungus in the foliose lichen Parmelia sulcata. Chlorphyll-a concentrations were measured as a means to quantify the proportion of the algal component. These concentrations were compared with changing abiotic factors. It was hypothesized that as light intensity increases, chlorophyll content will decrease. Also, as temperature increases, the chlorophyll content will decrease. As humidity increases, we expected chlorphyll levels to increase. Parmelia s. was extracted from Quercus rubra with respect to bearing and height of the lichen. Measurements and extraction took place in Pellston, MI June 4, 1995. It was found that the proportion of algal to fungal component in a lichen is not significantly affected by changes in light, temperature or humidity. Thus we can infer that a more complicated mechanism exists which regulates the balance of growth within the relationship.
http://deepblue.lib.umich.edu/bitstream/2027.42/54593/1/3033.pdf
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