The impacts of biological invasions

The Anthropocene is characterised by a continuous human-mediated reshuffling of the distributions of species globally.
Both intentional and unintentional introductions have resulted in numerous species being translocated beyond their
native ranges, often leading to their establishment and subsequent spread – a process referred to as biological invasion.
Biological invasions are associated with profound changes in the composition, structure, and functioning of recipient ecosystems,
plus substantial financial losses and disruptions to society, culture, and human well-being. These ecological, economic,
and socio-cultural impacts are interrelated, ubiquitous, and detrimental, yet they are often subjectively perceived
or inaccurately quantified. Persistent knowledge gaps remain, however, which limit our understanding of the complex
and multifaceted causes and mechanisms of invasion impacts. To overcome these gaps and comprehensively capture
all related facets pertaining to the nature and diversity of invasion impact, this scoping review of academic studies, grey
literature, and expert reports provides a conceptual model for interpreting invasion impacts, structured around three
interrelated pillars: impact domains, challenges in the study of impacts, and available risk- and impact assessments.
We initially explore the various mechanisms and consequences of ecological, economic, and socio-cultural invasion
impacts and their temporal dynamics, substantiating these with relevant empirical examples. We then review common
challenges and fallacies in studying invasion impacts, including context specificity and inter-comparability of impact
magnitudes, challenges associated with quantifying non-ecological impacts, and research biases, before synthesising
how risks are analysed and impacts assessed, and how these assessments ultimately inform management decisions. Our
review underscores the multifaceted and complex nature of invasion impacts, and that effectively addressing biological
invasions requires more than isolated, reactive interventions; it calls for globally coordinated, proactive action underpinned
by reliable scientific knowledge, sincere political commitment, and broad public engagement. Drawing on nearly
a century of literature and global expert contributions, this work offers a comprehensive, nuanced, and timely overview of
the potential consequences of biological invasions, providing a valuable foundation for informing future research directions,
management interventions, and policy development.