Abstract

In recent years, the importance of sagebrush to shrub-steppe ecosystems and associated plant and animal species has been recognized. The historical removal of herbaceous species by excessive and uncontrolled livestock grazing on many of our sagebrush ecosystems has resulted in a stagnant state where dense, competitive stands of sagebrush prevent herbaceous species from recovering. Most early research on sagebrush control was directed toward eradication to increase herbaceous forage for livestock production, rather than sagebrush thinning to improve shrub vigor and understory production for wildlife habitat and community diversity. Mechanical treatments have the ability to retain shrub and herbaceous components, while improving diversity within degraded sagebrush communities. This study evaluated the effects of 6 mechanical treatments and revegetation of a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) community in northern Utah that were treated in the fall of 2001 and spring of 2002 (aerator only). Disking and imprinting killed 98% of the sagebrush and significantly (p < 0.05) lowered cover and density of sagebrush more than any other treatment. Disking and imprinting was the only mechanical treatment to reduce cover and density of residual understory species, but also to successfully establish seeded grasses. One-way Ely chaining, 1-way and 2-way pipe harrowing, and aerating in the fall and spring reduced sagebrush cover from greater than 20% to less than 5% and reduced density by about half. Two years after mechanical treatment surviving sagebrush had greater leader and seed stalk growth than untreated sagebrush. Choice of a mechanical treatment to increase and diversify the perennial herbaceous component and retain the shrub component of sagebrush communities depends on the amount of residual herbaceous species, as well as economics. Chaining is potentially most economical for diversifying communities with a residual herbaceous perennial component. It is uncertain whether successful revegetation from disking and imprinting was a result of significant reduction in sagebrush, residual perennial herbaceous species, or both. Response of sagebrush communities with a very limited perennial herbaceous understory needs to be tested to determine how much and what kind of mechanical reduction in sagebrush is needed for successful revegetation.

Degree

MS

College and Department

Life Sciences; Biology

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2005-03-11

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd718

Keywords

rangeland revegetation, habitat restoration, sagebrush steppe, chaining, harrowing, imprinting, aerating

Language

English

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