Plant Functional Composition, Ecological Niche Distribution, and Biodiversity Measures Across Urban Grasslands of Different Size, Localisation, and Type

Abstract

Urban grasslands (UGs) are among the most abundant type of green infrastructure in cities worldwide. They deliver a range of ecosystem services and perform numerous ecosystem functions. To ensure the multifunctionality of UGs, enhancing their biodiversity is crucial; however, owing to urbanisation effects and inappropriate management, UGs often have low species richness. While urban vegetation has been studied in general, detailed ecological insights into the patterns of vegetation functional, ecological, and compositional attributes across different size, localisation, and type of UGs are still lacking. Better ecological knowledge regarding UGs vegetation will facilitate management aimed at increasing their biodiversity and multifunctionality. In the city of Wrocław, Central Europe, we surveyed 244 UG patches which differed in size (small, medium, and large), type (lawns, embankments, road verges, and UG in parks), and locality (city centre and periphery). Functional traits composition, ecological niches distribution, and biodiversity measures were assessed based on plant species composition and information obtained from open databases, including disturbance indicator values for plants. The results showed that the main trade-offs in functional traits composition and species niche distribution were related to biomass loss associated with mowing frequency. The examined factors (patch size, locality, and type) significantly affected UG vegetation, with each having distinct influences on biodiversity and multifunctionality. Many factors related to urban expansion (e.g., urban heat islands, soil reaction change, landscape fragmentation, biological invasions) are difficult to mitigate. However, proper management, such as extensive mowing, could help moderate the negative impacts of urbanisation. Increasing or maintaining a high proportion of forbs in vegetation would also enhance the multifunctionality of UGs.