Masters Theses

Date of Award

8-1985

Degree Type

Thesis

Degree Name

Master of Science

Major

Botany

Major Professor

David K. Smith

Committee Members

B. E. Wofford, P. S. White

Abstract

Epiphytic bryophytes were intensively sampled on 13 yellow buckeyes (Aesculus octandra Marsh.) located in a cove hardwood forest in the Great Smoky Mountains National Park. Cover and frequency values for the epiphytes were obtained with the use of a 14 x 14 cm quadrat.

The four cardinal compass points (north, east, south, and west) were sampled by four vertical transects centered on these exposures of the phorophyte. The transects extended from the tree base upward to a height of 1.5 m. At each of the four compass points the width of the vertical transect was defined by the distance circumscribed by a 20° arc of the tree's circumference with the center of the arc located at the compass point.

The vertical distribution of the epiphytes on each of the four aspects sampled was examined using ordination (DECORANA) and classification (TWINSPAN) techniques. These two complementary approaches revealed the presence of distinct vertical distribution patterns among the epiphytes. Thamnobryum alleqhaniense, Anomodon ruqelii, Metzqeria conjuqata, Eurhynchium hians, and Thuidium delicatulum occurred in the lower region of the transects while Brachythecium oxycladon occurred in the lower and middle regions but was most abundant in the lower region. Anomodon attenuatus and Anomodon rostratus were ubiquitous species on all four aspects. Radula obconica, Anomodon minor, and Lejeunea ulicina were present in low cover in the middle region of the transects. Cololejeunea biddlecomiae occurred sporadically throughout the transects on each of the four aspects. Forsstoemia trichomitria, Frullania brittoniae, Porella platvphylloidea, Radula complanata, Schwetschkeopsis fabronia, Neckera pennata, Homalotheciella subcapillata, Haplohymenium triste, and Dicranum viride were present in the upper and middle regions of the transects. Ulota crispa, Amblysteqium varium, Leucodon julaceus, and Frullania eboracensis were restricted to the upper region of the transects.

The information generated on the vertical distribution patterns of epiphytes by ordination and classification techniques demonstrated that the aspectual effect was most pronounced on the south aspect presumed to be due to the presence of drier microclimatic conditions. Species occurring in the upper and middle regions of the transects on the north, east, and west aspects extended further down the transects on the south aspect, possibly the result of a reduction in competition with other species, primarily the ubiquitous Anomodon attenuatus and Anomodon rostratus. The cover of many of the epiphytes on the south aspect was also considerably reduced as compared to the other three aspects.

A comparison of means (i.e., mean cover/tree/aspect) showed that the north, east, and west aspects were not significantly different from each other yet all had significantly greater cover than the south aspect. Coefficients of community, calculated for all possible two-aspect combinations, also revealed that the north, east, and west aspects were more similar to each other than they were to the south aspect.

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