Award Date

5-1-2019

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Committee Member

Scott Abella

Second Committee Member

Dale Devitt

Third Committee Member

Jef Jaeger

Fourth Committee Member

Carolee Dodge-Francis

Number of Pages

89

Abstract

A better understanding of key ecological restoration techniques can inform land management in the Southwest on restoration options for areas infested by invasive grasses that can pose threats to ecosystems, from changes in nutrient cycling to altered fire regimes. In the semi-arid desert of Glen Canyon National Recreation Area (GLCA), several exotic grasses pose risks to local ecosystems: Saccharum ravennae, a relatively new invasive perennial grass, and Bromus rubens and Bromus tectorum, widespread annual grasses. In this study, multiple ecological restoration techniques were implemented to assess their effects on native and nonnative vegetation on sites invaded by the non-native grasses S. ravennae, B. rubens, and B. tectorum. S. ravennae seeds were tested for germinability after periods of water submersion to address how fluctuating water levels of Lake Powell within GLCA may affect the spread S. ravennae. Results showed that S. ravennae populations declined within three months of herbicide treatment and manual removal treatment, but began to return by eleven months post-treatment, suggesting the need for repeated treatments to maintain low populations. Herbicide treatment on B. tectorum and B. rubens did not significantly decrease overall plot non-native cover; however, revegetation treatments yielded higher native plant cover than all other treatments. While shelters and catchments did not significantly affect survival of transplants on all revegetated plots, select plant species had higher survival rates than others. S. ravennae seeds were able to survive up to 16 months underwater, indicating the possibility for S. ravennae to survive periodic flooding and indicating challenges for managing this grass.

Keywords

Brome; Ecological restoration; Invasive species; Land management; Ravennagrass; Revegetation

Disciplines

Biology | Ecology and Evolutionary Biology | Environmental Sciences | Natural Resources and Conservation | Terrestrial and Aquatic Ecology

Language

English


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