Effects of Repeated Herbicide Use for Leafy Spurge (Euphorbia esula L.) Control on Rangeland Functioning
| dc.contributor.advisor | Bennett, Jon | |
| dc.contributor.advisor | Helgason, Bobbi | |
| dc.contributor.committeeMember | Lamb, Eric | |
| dc.contributor.committeeMember | Kutcher, Randy | |
| dc.creator | Malis, Erin | |
| dc.creator.orcid | 0009-0003-0525-144X | |
| dc.date.accessioned | 2023-08-17T20:38:08Z | |
| dc.date.available | 2023-08-17T20:38:08Z | |
| dc.date.copyright | 2023 | |
| dc.date.created | 2023-11 | |
| dc.date.issued | 2023-08-17 | |
| dc.date.submitted | November 2023 | |
| dc.date.updated | 2023-08-17T20:38:09Z | |
| dc.description.abstract | Invasive species management poses a significant challenge to ecosystem restoration. Leafy spurge (Euphorbia esula L.) is an invasive weed in North America that can lead to declines in native plant diversity, forage productivity and have large effects on microbial communities, nutrient cycling, and overall ecosystem functioning. Herbicides are frequently used to control leafy spurge but can have non-target impacts on ecosystems and often need to be re-applied to maintain control, which may worsen effects. The objective of this study was to determine if repeated herbicide applications of a broadleaf specific herbicide (active ingredients: aminocyclopyrachlor and metsulfuron-methyl) for leafy spurge control negatively affects non-target plant species and alters microbial abundance and community structure and nutrient retention. We established an experiment in a leafy spurge infested mixed grass prairie to test the effects of three herbicide rates – never, once, and in two consecutive years – in areas both invaded and uninvaded with leafy spurge, on plant community composition and production, microbial abundance and community structure and soil carbon (C) and nitrogen (N) concentrations. With a single application we found that: leafy spurge was effectively reduced for two growing seasons but was recovering by the third, forbs and broadleaf species richness declined, and plant community composition was altered. A second application worsened these effects and significantly reduced shrubs. There was no improvement in grass production. Herbicide did not have significant effects on bacterial abundance and microbial community structure but with a second application did lead to a decline in fungal and AMF abundance and an increase in the Gram-negative stress indicator. We also saw an initial increase in inorganic N, but a reduction in water-extractable organic carbon (WEOC) with a repeated application. These effects were most likely due to reductions in leafy spurge and native forbs and shrubs. Our results show that herbicides can have detrimental effects on non-target species and the plant community, which can lead to changes in the microbial community and nutrient concentrations and that these effects can be more pronounced with a repeated application. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | https://hdl.handle.net/10388/14894 | |
| dc.language.iso | en | |
| dc.subject | invasive species | |
| dc.subject | plant sciences | |
| dc.title | Effects of Repeated Herbicide Use for Leafy Spurge (Euphorbia esula L.) Control on Rangeland Functioning | |
| dc.type | Thesis | |
| dc.type.material | text | |
| thesis.degree.department | Plant Sciences | |
| thesis.degree.discipline | Plant Sciences | |
| thesis.degree.grantor | University of Saskatchewan | |
| thesis.degree.level | Masters | |
| thesis.degree.name | Master of Science (M.Sc.) |