Ellenberg’s indicator values provide insights into bryophyte distribution and diversity in Edinburgh, Scotland

•Background: Bryophytes are an important part of urban ecosystems, using both natural and man-made substrates. Climate, habitat availability, pollution and geology influence their distribution. •Aim: To determine the diversity of bryophyte species growing in Edinburgh and evaluate the ecological and climatic factors affecting their distribution, including pollution and urban heat island effects. •Methods: Edinburgh city centre and suburbs were divided into 1 km x 1 km squares (monads) and their bryophyte species and habitats were recorded. Climatic variables and Ellenberg’s indicator values (EIV) were used to elucidate species’ ecological preferences. •Results: We recorded 272 taxa (221 mosses, 50 liverworts, one hornwort). Cluster analysis of monads by their species composition resolved five groups with contrasting climate and EIV. Species-rich monads contained populations with a wider range of EIV than species-poor monads. Light, Reaction and Moisture EIV decreased at both upper and lower ends of their ranges in species-poor monads, while Nitrogen only declined at the least fertile end of the scale. Species with high EIV Nitrogen occur in higher proportions in the city centre. Habitats resolved into two main clusters, with the species composition of G (gardens, parks and grounds) and R (roads, paths and pavements) distinct from the remaining habitats, with significantly higher rainfall and significantly lower Reaction and Nitrogen EIV. All habitats contained unique species. Widespread generalist species are characteristic of warmer, brighter, drier, more alkaline environments with higher Nitrogen values than less widespread species. •Conclusions: Edinburgh is a city rich in bryophytes. Even the most built environments contain unique species. Conservation of species diversity requires a variety of substrates available for colonisation, and protection of precious habitats in open spaces.