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In this dissertation, I describe some of the role that lichens play in the New Jersey Pinelands ecosystem. I begin with a review of worldwide lichen communities, and discuss some mechanisms through which lichen communities have previously been found to be influential in the ecosystems where they occur. In the first chapter, I have quantified the structure of the lichen communities where extensive lichen mats are present. I found that extensive lichen mats occur in areas with low soil organic matter content, that have experienced no recent fires, and that exhibit wide ranges of canopy cover. Most lichen mats communities were similar to each other in composition, except for the southernmost site, the Manumuskin River Preserve. In my second chapter, my collaborators and I investigated the influence of these lichen mats on trends in soil moisture, soil chemistry, soil microbial community activity, and soil arthropod presence, through a transplant experiment. We found that the influence of lichens on soils varies with soil conditions and with climate conditions. In low moisture conditions lichens contribute to soil retention of moisture, and when soils have higher inorganic phosphorus availability, lichens significantly reduce extractable phosphorus concentrations. Lichens also promoted higher densities of collembolans in the summer. The microbial community activity did not respond dramatically to lichens; although lichens are known to leach phenolic compounds into the soil, lichens did not promote increased production of any enzymes associated with degradation of recalcitrant carbon compounds. The lichens did not have significant effects soil ammonium or nitrate levels or on microbial community activity. My third chapter tests whether lichens can mediate human-induced environmental changes by investigating how lichens process excesses of nitrogen; we found that at high loads of nitrogen, lichens can depress the quantities of total nitrogen delivered to the soil and to the groundwater that leaches through it. Lichens prevent ammonium from being accumulated in the soil although not significantly more than any aboveground cover. Results from these studies clarify some of the functional significance of temperate forest lichens.

ETD_7168

Ph.D.

Includes bibliographical references

by Natalie Madeleine Howe

doi:10.7282/T39P33TX

ETD doctoral

The author owns the copyright to this work.