Species–park networks reflect the spatial structure of urban green infrastructure

As cities expand, natural and semi-natural habitats are increasingly restricted in extent and connectivity, posing major challenges for biodiversity conservation. Urban parks, as nodes of green infrastructure, improve ecological connectivity in the urban landscape, yet their functional role in supporting urban plant communities remains challenging to quantify. This study aimed to investigate whether differences in the functional role of urban parks are reflected by their spatial location within the green infrastructure. We applied a bipartite species-park network approach to assess the role of urban parks in supporting plant species in three historic cities in north-eastern Italy. In 2024, we surveyed 57 parks, recorded vascular plant species in nested plots and measured park attributes including area, distance to the city centre, distance to other parks and tree canopy cover. Species–park networks were used to quantify the functional role of each park through park specialisation, importance, compositional representativeness, and colonisation potential. Statistical models showed that parks further from the city centre supported richer plant communities and hosted species more dependent on individual parks, while parks at intermediate distances from the centre acted as compositional links between parks closer and further from the city centre. Parks with greater tree canopy cover tended to host species that achieved comparatively higher local cover but showed reduced compositional representativeness to other parks. Our results revealed that the functional role of parks in supporting plant communities was strongly associated with their spatial location within the green infrastructure, providing insights for urban biodiversity conservation and landscape planning.