Abstract
Cities are increasingly recognized as hotspots of biological invasions, yet the dominant body of invasion science has historically focused on rural landscapes, conservation areas and relatively intact ecosystems. As a result, key concepts, frameworks, and management tools were developed with natural systems in mind, then transposed to urban contexts with limited adaptation (Gaertner et al., 2017b; Potgieter et al., 2019; Francis and Chadwick, 2015; Egawa et al., 2026). This transposition has, in some cases, proven adequate, particularly where urban populations resemble their non-urban counterparts in extent, growth rate and impact profile; the more pressing concern is that its adequacy has rarely been tested systematically across the diversity of urban contexts (Catford et al., 2022; Dyderski and Jagodziński 2019).
Within this broader context, invasive alien plants are particularly prominent in cities, both in species richness and in the magnitude of their ecological and social impacts (Kühn et al., 2017; Liu et al., 2025). Urbanization transforms abiotic conditions, disturbance regimes, species pools and human–nature interactions in ways that profoundly reshape plant invasion pathways, establishment filters, impact profiles and feasible management options, although the extent of this reshaping varies considerably with city size, climate, governance capacity and development history (Potgieter et al., 2024; Gaertner et al., 2017). Cities concentrate trade, transport, and human density, so they function simultaneously as entry points for non-native species and as stepping stones across regions that continually feed propagules into surrounding landscapes (Gaertner et al., 2017b). At the same time, urban residents depend on multifunctional green and blue infrastructure (ie water bodies) for recreation, climate regulation, aesthetics and cultural identity, which often involves intentional use of non-native species (Potgieter et al., 2024; Padayachee et al., 2017; Gaertner et al., 2017b).
These features raise a central question: are standard invasion frameworks [e.g., stage/barrier models and Environmental Impact Classification schemes (Kumschick et al., 2024; Blackburn et al., 2011)] and management approaches such as the Unified IAS management framework (Robertson et al., 2020), designed largely for natural systems, fit for purpose in cities?
Emerging urban invasion literature suggests that cities are not well served by frameworks built for natural systems, because urban invasions show distinct dynamics, impacts often combine benefits and harms, and management is shaped by social conflict, stakeholder diversity, and governance complexity (Gaertner et al., 2017; Potgieter and Cadotte, 2020; Gaertner et al., 2016).
This points to a more specific gap: Urban invasion ecology has increasingly documented how propagule pressure, connectivity, environmental filtering, and disturbance differ in cities, but urban management tools have not kept pace. Only a few studies are applying explicit thresholds or decision triggers and many governance frameworks are still adapted from rural or natural systems rather than designed for fragmented, stakeholder-rich urban landscapes (Potgieter et al., 2022; Gaertner et al., 2016; Potgieter and Cadotte, 2020).
This does not imply that natural-system frameworks are inapplicable in cities; stage-based models and impact classification schemes remain a useful starting point for newly detected incursions and clearly harmful species, while conventional eradication or containment remains appropriate where invasions are still limited in extent and management is feasible (Blackburn et al., 2011; Robertson et al., 2020). Rather, the emerging literature indicates that these frameworks require systematic adaptation, not replacement, for the distinct conditions cities present.
In this paper, we advance the argument that urban invasive alien plant management cannot rely solely on the application of natural-area tools at smaller and more fragmented scales, and instead requires explicit reframing as the management of socio-ecological, novel systems, while retaining and adapting elements of conventional practice where these remain effective (Francis and Chadwick, 2015).
Building on existing literature, our contribution does not rest on establishing that urban invasions differ from those in non-urban systems, a point already substantiated by prior reviews (Gaertner et al., 2017; Potgieter and Cadotte, 2020; Cadotte et al., 2021). Instead, we integrate urban-specific ecological processes, ecosystem service and disservice trade-offs, environmental justice, and planning and governance instruments into a single operational decision architecture, and we identify which elements of classical invasion theory require reformulation for urban socio-ecological systems.
