Making Some Invasive Plant Lists and Checking Them Twice
Summary written by Bethany Bradley, edited by Annette Evans
Summary
A recent study (Beaury et al. 2021) showed that invasive plant regulations (i.e. invasive plants that are prohibited from sales) are inconsistent across state borders and fail to proactively prevent the introduction of species that could become invasive with climate change. However, the factors leading to this inconsistent and reactive regulatory landscape are unknown. Bradley et al. (2022) take a deeper look at invasive plant risk assessment protocols (i.e. ‘weed risk assessments’) and evaluate invasive species lists across six Northeast states (Connecticut, Maine, Massachusetts, New Hampshire, New York, and Vermont). They ask whether the inconsistent/reactive regulations are more likely driven by differences in the risk assessment protocols or in differences in the sets of species evaluated. Inconsistent sets of regulated species were primarily due to different sets of evaluated species, while reactive regulations stemmed from a lack of emphasis on evaluating range-shifting species. The risk assessments used by each state were quite different in scope and did not contain language that would prevent proactive evaluation and regulation of range-shifting species, although assessors should consider climate change when evaluating the ‘potential’ range and spread of invasive plants. However, all the risk assessments shared a common core set of criteria - thus, completed evaluations could be readily shared across state borders. To support consistent and proactive risk assessments across Northeast state borders, Bradley et al. provide tables of regulated species, evaluated species, and high-impact, range-shifting species.
Take home points
Inconsistent and reactive invasive plant regulations in the Northeast are likely due to different sets of evaluated species rather than fundamental differences in weed risk assessment design.
Risk assessment protocols focus on a common core set of criteria, so sharing risk assessments across state borders would support better regional regulation.
Management implications
The following information in the manuscript and supporting tables can support information sharing to build more consistent and proactive state regulations:
Table 1. A list of common criteria used in invasive plant risk assessments (aka weed risk assessments) across Northeast states.
Table S1. A list of all species that are regulated by one or more Northeast state, including how widespread the species is and whether it is available as an ornamental.
Table S2. A list of all species that have been evaluated for invasiveness (including the outcome of the state’s risk assessment) by one or more Northeast state as of April 2021.
Table S4. A list of high-impact, range-shifting invasive plants that are expanding into Northeast states.
Keywords
Invasive plant, Prioritization, State regulation, Risk assessment, Proactive management, Impact studies, Management Efficacy