Date of Award:

5-2013

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

Eugene W. Schupp

Committee

Eugene W. Schupp

Committee

Thomas A. Monaco

Committee

Karin M. Kettenring

Abstract

The sagebrush-steppe communities of the Great Basin have been dramatically transformed by the invasion of the non-native annual grass cheatgrass. In many areas of the Great Basin, this invasion has resulted in the loss of native plant species and ultimately the conversion to cheatgrass-dominated communities. As healthy sagebrush communities provide multiple ecosystem services such as diverse wildlife habitat, forage for cattle grazing, and water filtration, restoration of these communities is a high priority to landowners and land management agencies. Established perennial grasses can successfully compete with non-native annual grasses and increase the resistance of plant communities to invasion by non-native annual grasses. As such, re-establishing a healthy native sagebrush understory dominated by perennial grasses may be the key to restoring these communities. However, the restoration of native vegetation is difficult and has been met with limited success.

As a result, I was interested in investigating the effects of several restoration treatments intended to increase the success of aerially‐seeded native perennial grasses in cheatgrass-invaded sagebrush communities on perennial seedling emergence and soil seed bank density and composition. The restoration treatments assessed in this study were: 1) vegetation manipulations (50% sagebrush thinning, 100% sagebrush thinning, prescribed burning); 2) imazapic herbicide application (140 g active ingredient ∙ ha‐1, 210 g active ingredient ∙ ha‐1); 3) soil seedbed amendments (activated carbon addition, sucrose addition); and 4) seeding frequency (2 years of seeding, 3 years of seeding).

Herbicide and prescribed burning demonstrated potential for increasing seeded native perennial grass emergence success. Results also suggest that potential exists to increase native perennial grass emergence through an increase in seeding frequency. Additionally, these results suggest that herbicide and sucrose may be useful tools for reducing exotic species richness in cheatgrass-invaded systems. Herbicide also showed potential for reducing cheatgrass seed bank densities. Results also demonstrated that the reductions in cheatgrass seed bank densities observed immediately after fire are still observed 1 year post-burn.

This study increased our understanding of the effects of some commonly used restoration techniques and seeding frequency on seeded native perennial grass success and seed bank dynamics in Great Basin cheatgrass-invaded sagebrush ecosystems.

Checksum

967633a9cd9115f5ab047e0c335056ec

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .