Location: Natural Resource Management ResearchTitle: Plant community and target species affect responses to restoration strategies Author
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2010
Publication Date: 7/1/2010
Citation: Hendrickson, J.R., Lund, C.B. 2010. Plant community and target species affect responses to restoration strategies. Rangeland Ecology and Management. Interpretive Summary: Increases in Kentucky bluegrass and smooth brome on northern Great Plains rangelands have impacted seasonal forage distribution, lowered plant diversity and increased carbon and nitrogen losses from the ecosystem. We evaluated five different restoration strategies for reducing the amounts of these invasive perennial grasses in rangelands. We found that fire and herbicide caused the greatest reduction in Kentucky bluegrass but mowing and raking reduced smooth brome the most. Community composition and time following treatment application impacted the results. Our results suggest that a single restoration strategy is not applicable for both these invasive species and successful strategies will need to incorporate both the invasive species and the community in their planning.
Technical Abstract: Increases in Kentucky bluegrass and smooth brome on northern Great Plains rangelands have the potential to negatively impact ecosystem function, lower plant diversity and alter seasonal forage distribution, but control strategies are lacking in the region. A project was initiated on a heavily invaded 16 ha grassland that had not been grazed or hayed for at least 20 years. Five restoration treatments and a control were initiated in 2003 on communities dominated by 1) smooth brome (Bromus inermis Leyss.), 2) Kentucky bluegrass (Poa pratensis L.), 3) native grasses, 4) a mix of introduced species and 5) smooth brome and Kentucky bluegrass. Restoration treatments were 1) late-April burn, 2) late-April burn followed by imazapic at 17.3 oz. ai ha-1, 3) imazapic only at the same rate, 4) mowing, 5) mowing followed by litter removal and 6) control. We found that treatment responses were affected by target species and community. Generally, burning followed by imazapic reduced Kentucky bluegrass in the species composition but smooth brome was reduced by mowing followed by raking. In both instances, the treatment that reduced the amount of one invasive species in the species composition tended to result in the other increasing. In 2005, responses of Kentucky bluegrass, other invasive species and native grasses to restoration treatment differed depending on community. Burning followed by imazapic reduced live grass biomass in all communities except the native in the year following treatment. This response disappeared by the third year of the study. The reduction in live grass biomass may limit the use of burning followed by imazapic for producers. Our data emphasized that effective control of perennial invasive grasses will incorporate community and species responses.