Browsing by Author "Wragg, Peter"
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Item Categorization of literature pertaining to the use of revegetation in suppressing invasive plant species(2018-05-29) Schuster, Michael; Wragg, Peter; Reich, Peter; schuster@umn.edu; Schuster, Michael JItem Human impacts on how savanna plants interact through fire, resources, and microclimate(2015-08) Wragg, PeterGrasslands and savannas harbor immense plant biodiversity. This biodiversity is threatened by land transformation. Moreover, the biodiversity of even intact ecosystems is affected by widespread human impacts on environmental factors-- particularly resources, fire, and climate-- that underlie interactions among plant species and structure plant communities. This dissertation examines how plants interact by affecting, and responding to, their environment. Much research has examined how plants interact by depleting shared limiting resources such as nitrogen (i.e., resource competition), and how increasing nitrogen deposition causes biodiversity loss; this research has been mainly north-temperate. To widen understanding of this issue, I examined the roles of multiple nutrients in structuring endemic-rich grasslands of conservation concern on highly weathered soils in South Africa, as part of the globally distributed Nutrient Network experiment. It is less clear how plants interact through fire and microclimate. I investigated how grasses differ from other herbaceous plants (forbs) in their effects on fire behavior and resource availability, and how fire and resources in turn affected savanna tree establishment, in a 16-year biodiversity experiment. I also investigated how plant diversity and composition interacted with experimentally simulated global warming to determine microclimate and resource availability, and how microclimate and resource availability in turn affected seedling establishment of 32 savanna herb and tree species. This research on the multiple ways in which plants interact by influencing their environment sheds light on how human actions alter grassland and savanna biodiversity.Item Managing Invasive Buckthorn(University of Minnesota College of Food, Agricultural and Natural Resource Sciences, 2022-06) Bernhardt, Carolyn; Koop, Heather; Larkin, Daniel; Lee, Christine; Morey, Amy; Schuster, Mike; Venette, Rob; Wolf, Tiffany; Wragg, Peter; Minnesota Invasive Terrestrial Plants and Pests Center, College of Food, Agricultural and Natural Resource ScienceThere are two types of invasive buckthorn in Minnesota: Common (European) buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus). Both species were introduced to Minnesota as ornamental plants and have now spread widely across the state. They outcompete native plants, suppress growth of canopy tree seedlings, and reduce habitat quality for wildlife. Both species are listed as restricted noxious weeds in Minnesota (https://www.mda.state.mn.us/plants-insects/minnesota-noxious-weed-list) and both are ranked high on the Minnesota Invasive Terrestrial Plants and Pests Center’s (MITPPC) research priority list (https://mitppc.umn.edu/invasive-species-prioritization). Many landowners in Minnesota work to remove buckthorn from their property by hand-pulling, using removal tools, or treating with herbicide. But preventing buckthorn from coming back remains a challenge. Removing buckthorn increases the availability of key resources like light and nutrients that enhance plant growth. Unfortunately, these resources are often quickly used by new buckthorn plants arising from seed or resprouting from cut stumps. As a result, buckthorn is particularly good at re-invading an area, and often rapidly returns after removal. Meanwhile, native plants are often slow to return because their seed banks have been depleted by buckthorn dominance. In this toolkit: • Current and ongoing buckthorn management research at MITPPC that can help • How to identify glossy and common buckthorns • How to remove buckthorn • How to replant native vegetation to prevent future reinvasion