More than 500 invasive plant species are currently taking root across the U.S., a number that is expected to increase as climate change allows invasive species to shift their growing ranges and move northward. Because invasive plants are a leading driver of native biodiversity loss, the ecological toll of these invasions promises to be severe. According to a new article in the Journal of Applied Ecology authored by a team including NE CASC Principal Investigator Bethany Bradley and NE CASC Fellows Evelyn Beaury and Emily Fusco, this problem is compounded by inconsistent regulations within the U.S., where varying state restrictions on invasive species undermine governmental efforts to respond adequately to this threat.
Despite this bleak situation, the team contends that states are equipped with an effective mechanism to combat invasive species--namely prohibited plant lists--which are compiled and maintained by state and county-level officials to prevent intentional introductions of known invasive and weedy plants. Unfortunately, the authors say, a lack of overall coordination imparts a patchwork quality to efforts at controlling invasive plants. Their study found significant disparities in the number of invasive plants regulated by individual states, where anywhere between 0 and 162 plants may be prohibited. Importantly, contiguous states often regulate very different sets of species: on average, only 20% of the plants listed as invasive in one state will show up on their neighbors’ lists. Moreover, states rarely anticipate new plant invasions: 90% of the time states only list a plant as invasive once it has already become present in their state, making it more difficult to eradicate.
“We’re missing an opportunity to prevent invasions before the species are widespread,” said Emily Fusco, an NE CASC researcher and one of the study's coauthors. “Our work shows that states are not creating prohibited plant lists in a proactive way.”
Fortunately, though, this approach can be improved. “It’s not that the states are doing a bad job,” said Evelyn Beaury, lead author of the study and an NE CASC Fellow. “We don’t need to reinvent the wheel – we just need to have more conversations about what happens across state borders. We need to give managers the infrastructure and resources to work together.”
Such an approach is evident in the work being undertaken by the Regional Invasive Species and Climate Change (RISCC) Management Network, which is facilitating coordinated, multi-state action against invasive species through the development of a regional invasive species council comprised of invasive species managers from New England and New York. “State officials want to improve coordination and share resources across borders,” says Bradley, who is a cofounder of the RISCC Management Network. “They are thrilled to have more ways to exchange information.”