Long-term treatment leads to reduction of tree-of-heaven (Ailanthus altissima) populations in the Buffalo National River

• Published in: Invasive plant science and management 2020-12, Vol.13 (4), p.276-281
• Main Authors: Young, Craig C., Bell, Jordan C., Morrison, Lloyd W.
• Format: Article
• Language: English
• Subjects: Adaptive management; Ailanthus altissima; Case studies; CASE STUDY; Control; eradication; Forests; herbicide; Herbicides; imazapyr; Introduced species; Invasive plants; Invasive species; Land management; monitoring; national park; National parks; point mapping; Populations; project effectiveness; Riparian forests; Rivers; Trees; Triclopyr; Vegetation
• ISSN: 1939-7291; 1939-747X
• DOI: 10.1017/inp.2020.28

In this case study, we used point mapping data to evaluate long-term treatment of invasive tree-of-heaven [Ailanthus altissima (Mill.) Swingle]. This study at the Buffalo National River included 21 project areas ranging in size from 0.02 to 11.3 ha and spanned 5 to 8 yr depending on the site. The control techniques varied depending on the year and included the application of herbicide, which also varied over the course of the study and included imazapyr, triclopyr, and triclopyr+fluroxypyr. Treatments during the first year reduced local A. altissima populations by an average of 66%. Long-term repeated treatments led to decreases of at least 90% in 70% of the project areas and at least 73% in 95% of the project areas. Only one project area was found to support no plants during the final treatment year. Ailanthus altissima increased at most project areas during an unusually wet year and was more likely to increase than decrease in intervals >1 yr with no treatment. Over the temporal and spatial scales of this case study, we observed high levels of control that will likely meet the specified levels and ecological benefits required in many similar efforts. Land managers must, however, make a long-term commitment of resources to achieve lasting control of this invasive species.