Garlic Mustard (Alliaria petiolata) Management Effectiveness and Plant Community Response

• Main Author: Coates-Connor, Erin
• Format: Others
• Published: ScholarWorks@UMass Amherst 2019
• Subjects: Garlic mustard; Alliaria petiolata; invasive plant; native communities; Invasive plant management; land management; Forest Biology; Forest Management; Weed Science
• Online Access: https://scholarworks.umass.edu/masters_theses_2/764; https://scholarworks.umass.edu/cgi/viewcontent.cgi?article=1823&context=masters_theses_2

The control and eradication of the invasive biennial herb garlic mustard (Alliaria petiolata) and the restoration of invaded forest habitats present important linked challenges to land managers in North America. Removing garlic mustard by hand and by glyphosate herbicide application have both been used as eradication strategies with mixed results. Each method has advantages and disadvantages, but they are rarely compared for effectiveness and community impact across multiple years of management. Some previous studies have shown improvements in species diversity and plant community composition following management, while others have found no differences. To better understand both garlic mustard population and native plant community responses to these two methods across a broad geographic range, we tested these two management methods for four years in seven northern hardwood forests in Massachusetts and New York State. We found that pulling juvenile and adult garlic mustard plants for four years significantly reduced adult abundance, while spraying had no effect compared to invaded control plots. In the plant community, we found no negative impacts of garlic mustard on species diversity nor increased diversity in managed plots following three consecutive years of management. Our results suggest that increased diversity should not be the primary goal of garlic mustard management at these sites and plant community monitoring at the site-specific scale should be explored. This study highlights how complicated decisions can be for managers when deciding which invasions to prioritize and how to measure plant community recovery.