Culminating Project Title
Managing Spotted Knapweed (Centaurea stoebe) Using Restoration Methods
Date of Award
Culminating Project Type
Biological Sciences - Ecology and Natural Resources: M.S.
College of Science and Engineering
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Keywords and Subject Headings
invasive species, spotted knapweed, ecological restoration
This thesis project addressed the effectiveness of integrating ecological restoration into traditional mechanical and chemical methods of invasive species control. Spotted knapweed, an abundant invasive plant species at Camp Ripley Military Training Site, is capable of prolific reproduction, and therefore, causes great ecological distress to the native community it invades. The purpose of this research was to determine if spotted knapweed can be controlled by re-introducing native prairie grasses to the disturbed sites at Camp Ripley, and ideally, apply these findings to the methods of invasive species control in native prairies across central Minnesota. Furthermore, the sequence of the application of selective, broadleaf herbicide (Milestone) and native grass seeding was varied in order to determine the sequence of treatments most likely to decrease the density of spotted knapweed, increase the density of target native grass species, and decrease the percentage of bare soil visible. Three research plots were used in the experiment: two of which received the native grass seeding in conjunction with the selective, broadleaf herbicide in varied order, one of which received only broadleaf herbicide. Data analysis, at the conclusion of the experiment in October 2016, showed that ecological restoration as an integrated method of control did not effect the spotted knapweed density, nor did the varied sequence of treatment applications. The broadleaf herbicide, Milestone, was solely responsible for the decrease in spotted knapweed density. A negative consequence of using Milestone was a decrease in species richness, including a negligible amount of target native grass species and increase in nonnative grasses and forbs. Finally, bare soil visible was not decreased in the experimental plots receiving both native grass seed and herbicide application. A supplemental greenhouse experiment was conducted January through March 2017 in order to determine if Milestone was responsible for lack of native grass growth at the end of the field experiment. Similar experimental methods were used, with the addition of an experimental group that lengthened the amount of time between herbicide and grass seed application to four weeks. Data analysis after ten weeks of growth showed that Milestone negatively affected native grass seedlings, regardless of treatment sequence or length of time between applications. Due to the nature of native prairie restoration, it is recommended that the site continue to be monitored over subsequent years for potential target grass population growth. Also, further research is recommended to determine a more appropriate chemical to integrate into a restorative method of control. Ecologists and land managers play a critical, cooperative role in determining control methods that allow native prairies to remain healthy and intact in order to resist invasive species known to degrade them.
Jacobs, Kelly R., "Managing Spotted Knapweed (Centaurea stoebe) Using Restoration Methods" (2017). Culminating Projects in Biology. 23.
I would like to thank my advisor, Dr. Jorge Arriagada, for his support and assistance throughout my research. Dr. Arriagada gave me a chance and took me on as his advisee, and for that I am thankful. The amount I’ve learned as his student is immeasurable. Next, I would like to thank my committee members, Dr. Anthony Marcattilio and Mr. Paul Hamilton, for their guidance and knowledge. I would also like to thank the Environmental staff at Camp Ripley, especially Jason Linkert, for allowing me the time and resources to complete my research, as well as direction and expertise with the technical aspect of land management. I am extremely thankful for the opportunity to have learned, first-hand, the process of invasive species management. For their assistance in the execution and data collection portions of my research, I would like to thank St. Cloud State University graduate and undergraduate students Laura Donahue, Joseph Weaver, and Jordan LeClair. I would also like to thank Dr. Leland Jacobs for his statistical analysis consultation. Last, but not least, I would like to thank my husband, Brian, for the encouragement to pursue my passions, the willingness to lend a hand at any moment of need, and the confidence he has in me to make a difference.