Using adaptive management to restore grasslands invaded by tall fescue (Schedonorus arundinaceus)

Authors: COON, JAIME - University Of Illinois; LYON, NICHOLAS - Iowa State University; Raynor, Edward; DEBINSKI, DIANE - Montana State University; MILLER, JAMES - University Of Illinois; SCHACHT, WALTER - University Of Nebraska

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2021
Publication Date: 3/16/2021
Citation: Coon, J.J., Lyon, N.J., Raynor, E.J., Debinski, D.M., Miller, J.R., Schacht, W.H. 2021. Using adaptive management to restore grasslands invaded by tall fescue (Schedonorus arundinaceus). Rangeland Ecology and Management. 76:84-94. https://doi.org/10.1016/j.rama.2021.02.001.
DOI: https://doi.org/10.1016/j.rama.2021.02.001

Interpretive Summary: This article evaluates the role of herbicide application, native plant seeding, and grazing management on plant community composition and structure in tall fescue-dominated pastures in Iowa. Tall fescue is a popular non-native forage species used throughout the southeastern United States as well as other regions, where a reliable forage is desired. An examination of grazed and non-grazed sites revealed a one-time herbicide (glyphosate) application in 2015 suppressed tall fescue through 2018. However, non-native grasses other than tall fescue, such as smooth bromegrass, increased on grazed sites after herbicide application. In contrast, a resurgence of native warm-season grass occurred on ungrazed sites which experienced one-time application of herbicide and native seeding. Our findings suggest native warm-season grass (forage) cover in tall fescue-dominated pastures at the eastern edge of the Great Plains can benefit from herbicide application to suppress tall fescue and subsequent rest from grazing.

Technical Abstract: Questions: Invasive grasses reduce habitat quality for multiple taxa and can negatively impact forage quality for livestock. Can a one-time herbicide application suppress the cover of invasive grass tall fescue (Schedonorus arundinaceus) over four years? Does seeding native plants in conjunction with herbicide enhance tall fescue suppression? To what extent will native plant cover return after herbicide and seeding? How are the effects of these treatments changed by grazing? Location: Grand River Grasslands, Ringgold County, IA and Harrison County, MO, USA. Methods: We studied control of tall fescue using a landscape-scale experiment in the eastern Great Plains employing adaptive co-management. The study design included three patches (average 8.7 ha) at each of the seven sites. Treatments included: (1) herbicide (glyphosate), (2) herbicide and native seeding, and (3) control. Four sites were grazed by domestic cattle. We sampled vegetation composition and structure during one pre-treatment year (2014) and four post-treatment years (2015-2018). Results: Tall fescue cover was reduced after a one-time glyphosate application, and this reduction was maintained over four years on grazed and ungrazed sites. We observed increases of warm-season grasses after herbicide and seeding, but only on ungrazed sites. Native grasses did not establish on grazed sites, where there was a resurgence of non-fescue exotic grasses. Percent cover of native forbs was near zero prior to seeding, but ranged from low to moderate levels afterward. Conclusions: Our results indicate a one-time application of herbicide can be used to reduce but not eradicate the invasive grass tall fescue, although other exotic grasses may replace tall fescue, especially on grazed sites. For plant community restoration to be successful, sites should be rested from grazing to give native seedings time to establish. Although eradication of invasive grasses is often infeasible in productive landscapes, restoring at least some native vegetation has the potential to protect ecosystem services provided by grasslands.