Indaziflam controls nonnative Alyssum spp. but negatively affects native forbs in sagebrush steppe

Jordan Meyer-Morey,Matthew Lavin,Lisa J Rew,Catherine Zabinski,Jane Mangold

doi:10.1017/inp.2021.31

Jordan Meyer-Morey, Matthew Lavin + Show 3 more

Open Access

https://doi.org/10.1017/inp.2021.31

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Abstract

AbstractNonnative plant invasions can have devastating effects on native plant communities; conversely, management efforts can have nontarget and deleterious impacts on desirable plants. In the arid sagebrush steppe rangelands of the western United States, nonnative winter annual species affect forage production and biodiversity. One method proposed to control these species is to suppress the soil seedbank using the preemergent herbicide indaziflam. Our goal was to evaluate the efficacy of indaziflam to control nonnative annual mustards (Alyssum spp.) and to understand potential nontarget effects of management on the diverse mountain sagebrush steppe plant communities within Yellowstone National Park. Six sites were established along an elevation gradient (1,615 to 2,437 m), each with high and low Alyssum spp. infestations. We applied 63g ai ha−1 of indaziflam in late summer of 2018 and evaluated plant community cover in situ for 2 yr after treatment and emergence of forb species from the soil seedbank ex situ. Indaziflam was highly effective at controlling emergence of Alyssum spp. for 2 yr. Richness and Shannon’s diversity of the nontarget plant community were significantly lower in sprayed plots than in the control, and both decreased along the elevation gradient. These reductions were due to a decrease in perennial forbs and native annual forbs in the sprayed plots; perennial graminoids were not affected. Overall, the aboveground and seedbank community composition was negatively impacted by indaziflam, and these effects were strongest for the native annual forbs that rely on annual regeneration from the seedbank. The effects of this herbicide to the nontarget community should be evaluated beyond the length of our study time; however, we conclude that indaziflam should likely be reserved for use in areas that are severely invaded and have seedbanks that are composed of nondesirable species rather than diverse, native mountain sagebrush communities.

Highlights

Nonnative plant invasions can have devastating impacts on native plant communities (Elton 1958; Mack and D’Antonio 1998; Tilman 1999; Vilà et al 2011)
The sagebrush steppe in the western United States is a diverse ecological community that provides forage for livestock operations and habitat for wildlife species (Beck et al 2012). This semiarid ecosystem is threatened by land use change, climate change, and nonnative plant invasions (DiTomaso 2000; Knapp 1996; Vasquez et al 2010), winter annual grass species that can alter fire regimes and disrupt ecosystem functions (Balch et al 2013; Billings 1994; Young and Fay 1997), creating novel plant communities far less diverse than the native communities they replaced (Allen and Knight 1984)
Our study examined the efficacy of preemergent indaziflam to control nonnative Alyssum spp. and evaluated impacts to the diversity of the nontarget plant community

Summary

Introduction

Nonnative plant invasions can have devastating impacts on native plant communities (Elton 1958; Mack and D’Antonio 1998; Tilman 1999; Vilà et al 2011). The sagebrush steppe in the western United States is a diverse ecological community that provides forage for livestock operations and habitat for wildlife species (Beck et al 2012). This semiarid ecosystem is threatened by land use change, climate change, and nonnative plant invasions (DiTomaso 2000; Knapp 1996; Vasquez et al 2010), winter annual grass species that can alter fire regimes and disrupt ecosystem functions (Balch et al 2013; Billings 1994; Young and Fay 1997), creating novel plant communities far less diverse than the native communities they replaced (Allen and Knight 1984)

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