Date of Award


Document Type


Degree Name

Master of Arts (MA)



First Advisor

Dr. Robert S. Egan


Environmental factors greatly influence what species of lichens may occur in a particular region. Among these factors is nitrogen deposition in the form of ammonia as a result of feedlot operations, which may be manifested by an increase in bark pH. Epiphytic lichens on trees located in close proximity to medium and large-scale feedlot operations in Eastern Nebraska were analyzed for bark pH levels, species composition and species abundance, then compared to trees located at a greater distance from feedlot operations. Five sites were selected based on the presence of trees and accessibility. Ten trees from each site were selected based on uniform diameter at breast height (dbh) and proximity to feedlot operations. In order to determine lichen coverage in cm2, high-resolution digital images were acquired, and then evaluated, employing Leica ERDAS Imagine 8.6, geospatial imagery analysis software. Bark material was collected from within 30 cm x 30 cm quadrats after images were acquired so that lichen species could be identified. Analysis revealed that bark pH was higher near feedlot operations when compared to “control” sites, and that nitrophilous lichen species dominated all sites. A statistically significant increase in nitrophilous lichen coverage was observed on trees near feedlot operations when compared to trees located at a greater distances.


A Thesis Presented to the Department of Biology and the Faculty of the Graduate College University of Nebraska In Partial Fulfillment of the Requirements for the Degree Master of Arts University of Nebraska at Omaha. Copyright 2006 Margaret K. Reed.

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