State lines and species divides: Inconsistencies and opportunities in invasive species policies across the eastern United States

Abstract

Invasive species are a threat to ecological and anthropogenic systems. In the United States, policies to coordinate funding and precipitate management action have been slow to emerge at the federal level, and there is a patchwork of regulation and legislation at the state level. This means that managers and policymakers, already facing limited budgets and evolving goals for action on invasive species, also face detrimental policy inconsistencies across states. Although previous research has explored state‐level invasive plant policy, policy relating to invasive invertebrate and vertebrate taxa (and across all three) is understudied. We expand upon previous taxa‐limited examinations of public policy related to invasives, looking across all taxonomic groups, including plants, to explore coherency of state regulations. We expanded the taxonomicscope of a database of policies in 21 contiguous eastern US states and used it to examine (in)consistencies in spatial trends for invasive species listed in policies across and within taxonomic groups. We examined the coherency of neighboring states and regional overlap of named species. We also analyzed correlations between distances among states and the species listed in the policy to examine regional trends. We found 1117 policy segments relevant to invasive species with 448 naming at least one taxon at the genus or species level. Of these, 35.3% were plants, 19.9% were invertebrates, and 44.8% were vertebrates. The distribution of taxa contained within policies varied across states, underscoring high variability in the proportion of taxa listed in the policies of neighboring states. Even lower policy coherency existed at the regional scale, particularly for invertebrate and vertebrate taxa. Our results indicate that policy inconsistency exists across all taxonomic groups, and the lack of attention to invasive invertebrates and vertebrates across state policies is particularly concerning. Policy inconsistency means that proactive states are susceptible to invasion from neighboring states where invasives are not similarly regulated. There is an opportunity to improve coordination between states to reduce vulnerability to invasives due to policy inconsistency.