Plant performance and diversity in roadside and railway habitats

Transport infrastructure is a pervasive feature of modern landscapes, and its ecological significance is increasingly recognised. Road verges constitute novel habitats characterised by traffic impacts and road maintenance activities, such as ground disturbance, vegetation management and dispersal processes. As a result, infrastructure habitats can function as refuges for native species, for example those declining in semi-natural grasslands, while also acting as corridors or entry points for invasive and ruderal plants. Understanding how plants establish, persist and interact with their environment in these habitats is therefore important from both ecological and conservation perspectives. This special issue of Nordic Journal of Botany brings together three studies that examine plant performance, diversity and community composition in roadside and railway environments from complementary perspectives. Frazee et al. (2025) explore plant communities in asphalted parking lots in the USA, representing some of the most extreme forms of human-made habitat. Their study shows how hard surfaces act as strong environmental filters, favouring species with particular dispersal and reproductive traits. By linking plant performance to pollination and propagule traits, the study provides insight into the mechanisms that allow plants to persist in highly altered infrastructure environments. Dániel-Ferreira et al. (2024) focus on road verges of high conservation value in Sweden and assess the impacts of the invasive alien species Lupinus polyphyllus on vascular plant diversity. Their results demonstrate that invasion effects are context-dependent, varying with the composition of the resident plant community. The study underscores the conservation value of road verges while also highlighting the challenges posed by invasive species and the need for targeted management strategies. Wiegmans et al. (2024) examine vegetation patterns along a historic railway corridor in northern Sweden and show that past disturbance events have had lasting effects on the distribution of ruderal plant species, in some cases outweighing contemporary climatic drivers. This long-term perspective emphasises the importance of legacy effects when interpreting present-day vegetation patterns in infrastructure habitats. Taken together, the contributions in this special issue illustrate the ecological complexity of roadside and railway habitats. They highlight the roles of environmental filtering, historical disturbance and invasive species in shaping vegetation in infrastructure-associated habitats. We hope that this collection will stimulate further research on infrastructure habitats and contribute to a more nuanced understanding of their role in changing landscapes.