Restoring Native Plants to Crested Wheatgrass Stands

Authors

  • Valerie A. Fansler,

    1. Graduate Research Assistant (at time of research), Department of Rangeland Ecology and Management, Oregon State University, Corvallis, OR 97331, U.S.A.
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  • Jane M. Mangold

    Corresponding author
    1. Assistant Professor, Land Resources and Environmental Sciences Department, Montana State University, Bozeman, MT 59717, U.S.A.
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J. M. Mangold, email jane.mangold@montana.edu

Abstract

Crested wheatgrass (Agropyron cristatum (L.) Gaertn.) is a nonindigenous grass introduced to North America for improving degraded rangelands. It is often criticized for forming nearly monotypic stands. Our objective was to determine the feasibility of restoring native plant species to crested wheatgrass-dominated rangeland. We investigated methods for suppressing crested wheatgrass followed by revegetation with a mix of native species. We tested five suppression treatments: undisturbed, low rate of glyphosate (0.25× recommended rate), high rate of glyphosate (recommended rate), 1-pass mechanical (disked once), and 2-pass mechanical (disked twice). Procedures were repeated in two trials in separate years. We sampled density and canopy cover of crested wheatgrass and density of seeded species for three (trial 1) and two (trial 2) years. Mechanical treatments increased crested wheatgrass density by 30–50%, whereas most other treatments were similar to the undisturbed (6.8 plants/m2). Crested wheatgrass cover decreased in mechanical and full herbicide treatments in trial 1 and was variable across treatments in trial 2. Seeded species density in all treatments (29 plants/m2) was greater than in the undisturbed treatment (18 plants/m2) 1 year after seeding in trial 1 and was similar across treatments (26 plants/m2) in trial 2. By the end of the study, though, all treatments resulted in similar seeded species density (<5 plants/m2). Results suggest suppression treatments were not effective and therefore did not improve restoration of native species in crested wheatgrass stands. Native species establishment may require subsequent management to favor persistence of native species and retard crested wheatgrass.

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