Local gardening practices shape urban lawn floristic communities

The large number of green space lawns in cities means that they shelter a high proportion of wild urban species, but the roles of landscape and management on the level of biodiversity in these spaces are little understood. We performed floristic inventories in 100 lawns in the southeast corner of Paris, France and linked their floristic diversity and composition to: (1) the characteristics of urbanization given by the Land Use Pattern and the distance from the centre of Paris, (2) local factors including luminosity and size of the lawn and (3) the type of management, including pesticide and fertilizer use, animal and public access, and mowing frequency. A total of 79 species were identified, of which 9% were naturalized. Distribution of the species was largely conditioned by the management methods applied to the green spaces: specific management strategies were associated with specific community traits and composition. As expected, the highest species richness and/or rarity were found in lawns submitted to private management, low use of pesticides and limited public access. But surprisingly high diversity was also sometimes found in small public lawns. The results establish relationships between human practices and characteristics of plant communities. We use them to make several recommendations on how best to optimize management of lawns with a view to conserving urban biodiversity.

► We analyzed floristic communities of 100 urban lawns submitted to various management practices and located in different districts of Paris (France).
► Local factors (use of pesticides, mowing frequency, public access and ownership) had a stronger effect on lawn floristic diversity than landscape factors.
► Only less than 10% of the lawn species recorded were exotics, that is relatively low considering the common pattern observed in cities.
► Specific management strategies were associated with specific community composition and traits.
► These quantitative results highlighted the benefits associated with ongoing differential management programmes in cities.