Exotic Plant Management at the Guilford Courthouse National Military Park, Greensboro, North Carolina, with Observations on the Spread and Control of Common Periwinkle (Vinca minor)
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Date
2009-03-18
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Abstract
The proliferation of invasive exotic plants in natural areas and managed systems can negatively impact productivity, biodiversity, and ecosystem function. Within National Parks, invasive exotic plants threaten the integrity of the natural communities that park managers attempt to protect. The National Park Service (NPS) has developed a strategic plan based on the concepts of integrated pest management and adaptive governance to manage invasive plants. Regional Exotic Plant Management Teams (EPMT) have been formed to provide a first response program for invasive plants and to assist park managers with all aspects of invasive plant management. Since 2003, the Southeast Exotic Plant Management Team (SE-EPMT) has worked with 18 parks in the southeastern U.S. to develop site-specific exotic plant management plans. The Guilford Courthouse National Military Park (GUCO) in Greensboro, North Carolina has been the focus of an ongoing invasive plant control program by the SE-EPMT. In addition to regular treatment of invasives, the SE-EPMT has sought to develop a management plan for GUCO that details the extent of exotic plant invasion at the park, prioritizes species for control, and offers recommendations for prevention, treatment, and monitoring of exotics.
This thesis presents an exotic plant management plan produced in coordination with the SE-EPMT for GUCO. It provides some of the basic information, analyses, and recommendations that have been missing or incomplete in exotic plant management at GUCO. An exotic plant census was conducted at GUCO during the summer of 2007; the park-wide distributions of 62 recorded species were later mapped in a geographic information system (GIS). Each species of concern was systematically ranked for control priority based on a suite of biological/ecological characteristics and site-specific conditions. Preventive strategies were identified based on existing and potential threats within and around the park. Treatment and monitoring recommendations were made for each species of concern. This plan should better inform management decisions and thereby increase the efficacy of control efforts and improve the likelihood of meeting long-term management goals.
Two additional studies were conducted on common periwinkle (Vinca minor L.), an exotic vine for which little biological or management information is available. Despite periwinkle’s status as a potentially harmful invasive in the U.S., no studies have directly compared herbicides or timing of herbicide applications for control of this species. Consequently, chemical control recommendations are varied and often conflicting. A study was conducted to determine the efficacy of several herbicides reported to control periwinkle. Two of the most commonly recommended herbicides were applied in the spring and fall to test for seasonal differences in control. After one growing season, fall-applied glyphosate at 4.5 kg ai/a provided 96% control of periwinkle and was the most effective of the 14 treatments tested. Other currently recommended herbicides had little or no effect on periwinkle. Glyphosate was about 20% more effective when applied in the fall. In contrast, triclopyr was about 50% more effective when applied in the spring.
Soil chemical properties have been shown to influence exotic plant invasion, and vice versa. We examined soils within and adjacent to periwinkle patches to determine if infestations were associated with particular soil properties. While we observed differences in soil properties from outside to inside of patches, no consistent patterns emerged across all patches. We concluded that most if not all observed differences in soil properties probably resulted from past human modifications at or around the initial planting site.
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Keywords
exotic plants, invasive plants, management, control, parks, herbicides, soil properties
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Degree
MS
Discipline
Natural Resources
