Are vascular epiphytes in urban green areas subject to the homogenization of biodiversity? A case study in the Brazilian Atlantic Forest

Urbanization is a disturbance process that can select species and result in biodiversity homogenization. Despite this, urban green areas shelter nature and are also important to human welfare. Epiphytes are an important functional group present in such areas, that are rarely studied. We evaluated the vascular epiphytic component in 26 urban green areas in the Brazilian Atlantic Forest and tested hypotheses related to the anthropogenic disturbances: 1) the community of epiphytes in urban green areas presents low richness and diversity of species; 2) there is low beta diversity due to flora homogenization represented by a reduced set of more tolerant species to disturbance. A total of 2288 trees (1563 representing phorophytes) and 110 epiphytic species were sampled. Six species were dominant, resulting in low diversity values, but some green areas had relatively high richness. The similarity found between the majority of the sampled areas suggests that epiphytic flora is subject to homogenization due to environmental filters. We found a high richness of species without adaptations to the epiphytic lifeform (accidental epiphytes) (42% of total sampled). Some results suggest that more comprehensive ecological and/or floristic studies about the epiphytes in the urban environment are necessary, such as Orchidaceae as the second richest family (since it is often poor in urban areas). More information about the species distribution patterns are necessary, both regarding the anthropized environments and the relationships with exotic or native phorophytes, as well as to enhance the knowledge of the ecological functions played by the epiphytes in these places.