Master's Theses

Document Type

Thesis - campus only access

Date of Award

Fall 2003

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Karen Hickman

Abstract

Disturbance of ecosystems by road construction results in habitat fragmentation and edge effects. Studies assessing effect of road construction on the native plant communities and dispersal of exotic plant species have indicated this type of disturbance promotes invasion by exotic plants. I studied the relationship of recent road construction and spread of bull thistle (Cirsium vulgare (Savi) Ten.), a nonnative, invasive plant species found primarily along disturbed roadsides of Bryce Canyon National Park (BRCA) in southern Utah. Additionally, I assessed the effects of road construction and bull thistle on the plant community structure in BRCA. Community and population data were collected along four transects at six different sites. Three of the six sites were designated "disturbed" because of recent road construct ion and the other three sites were designated "undisturbed". Transects at each of these sites were placed at increasing distances from the main park road, Federal Highway 63. I hypothesized that the number of bull thistle individuals would decrease as distance from the road increased. I also hypothesized that the presence of bull thistle and road construction would affect plant community structure by decreasing species richness and diversity. Furthermore, I hypothesized that more non-native plant species would be present at sites that had been disturbed through recent road construction. Bull thistle was found only at Disturbed Sites, with the greatest density found on the transect closest to the road. Results also indicated Disturbed and Undisturbed Sites differed significantly with Undisturbed sites having higher species richness, species diversity, and species dominance relative to Disturbed sites. All parameters at Undisturbed and Disturbed Sites, though, decreased as distance from the road increased. Disturbed Sites were found to have a greater number of nonnative plant species than the Undisturbed Sites.

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Rights

© 2003 Margaret A. Kritsch

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