Invasive plants continue to threaten ecosystems, reduce biodiversity, and disrupt agriculture on a global scale. The 2022 ASHS workshop provided a collaborative platform for researchers, policymakers, horticulturalists, and conservationists to exchange knowledge, discuss current research, and propose effective solutions. The proceedings document is designed to serve as a valuable resource for professionals in horticulture, agriculture, environmental conservation, and land management.
Worldwide, invasive species (accounting for plants, pathogens, and animals) cause damage valued annually at $1.4 trillion globally (City of Portland, OR, Bureau of Environmental Services 2021;. Approximately 17% of the world's landmass is deemed highly vulnerable to nonnative plant invasions. More than half of the world's flora has been introduced to alien regions for use in gardening, agriculture, medicine, and other purposes, but these non-native ornamentals have caused a loss of biodiversity in native habitats in or near urban areas.
Estimates of the economic ramifications of invasive species (plants, pathogens, and animals) in the United States range from $40 billion to $120 billion annually (City of Portland, OR, Bureau of Environmental Services 2021. Nearly 40% of invasive plants in the United States were originally introduced as ornamentals. These same species affect almost every ecosystem of the country and continue to colonize new areas Vendors selling invasive plants were identified throughout the continental United States, and researchers deduced that this ready availability of invasive species was due to disjointed state regulations that fail to protect both ecosystems and economies. In addition to causing habitat disruption in natural areas, invasive plants are commonplace in horticultural settings (M.A. Schnelle, personal observation) and thus require management in the built environment.
Key Highlights from the Proceedings:
Comprehensive Risk Assessment - Researchers examined high-risk invasive species, assessing their impact on local ecosystems and identifying areas most vulnerable to their spread.
Innovative Control Techniques - The workshop showcased new approaches to control invasive species, including biological, chemical, and manual strategies tailored to specific environmental contexts.
Policy Recommendations - Panel discussions outlined regulatory measures that can support effective management, such as stricter border controls, early detection protocols, and funding for community-based initiatives.
Case Studies - Attendees reviewed successful local and regional programs, highlighting strategies that can be adapted for wider application across the United States.
Many researchers believe humans are responsible for the sixth mass extinction in history as a result of changing global climate, eliminating species directly, spreading pathogens, fragmenting habitats, and introducing nonnative species. University students are exposed to limited plant content, particularly with regard to identification, compared with material focused on animals. Consequently, they argue that fewer plant scientists are being mentored and even fewer scientists are being educated about plants, which they characterize as a self-accelerating cycle coined "the extinction of botanical education
Nearly all scientists agree that it is imperative to identify priorities, targets, and actions for the long-term social and ecological management of invasive nonnative species.. However, as reported in this workshop, native status does not automatically mean a plant will exhibit "good behavior." It is therefore critically important to recognize that some native plants can grow as aggressively-and cause similar damage to diverse ecosystems-as nonnative species.
According to the authors of this report, "Throughout history, the ornamental industry has unintentionally but unequivocally contributed to the rise of invasive species in our natural areas. In response, significant progress has been made in phasing out invasives and replacing them with species and sterile cultivars that are ecologically friendly and more desirable for landscapes and gardens."
Dr. Schnelle is the Shackelford Endowed Professor of Floriculture and Extension Ornamentals-Floriculture Specialist at Oklahoma State University. He works primarily with the Oklahoma greenhouse and nursery industries including the Oklahoma Nursery and Landscape Association (www.oknla.org).
Dr. Wilson is a Professor of Environmental Horticulture at the University of Florida Institute of Food and Agricultural Sciences. Her research focuses on characterizing the invasive potential of ornamental plants and native plant propagation and production.
The full report can be found on the ASHS HortTech electronic journal website at: https://doi.org/10.21273/HORTTECH05285-23
Established in 1903, the American Society for Horticultural Science is recognized around the world as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting and encouraging national and international interest in scientific research and education in all branches of horticulture.
Comprised of thousands of members worldwide, ASHS represents a broad cross-section of the horticultural community-scientists, educators, students, landscape and turf managers, government, extension agents and industry professionals. ASHS members focus on practices and problems in horticulture: breeding, propagation, production and management, harvesting, handling and storage, processing, marketing and use of horticultural plants and products. To learn more, visit ashs.org.
