An urban bryophyte hotspot in an industrial city: the case of Ostrava Zoo (Czech Republic).

Bryophytes disperse efficiently via wind-borne spores, yet long-distance transport alone does not guarantee successful establishment at the deposition site. Species-rich hotspots are expected to arise where a sustained regional diaspore supply coincides with a high diversity of suitable substrates, creating both safe sites for colonization and stepping-stone nodes for further dispersal. Here, we use the Ostrava Zoo, located in the core of a heavily industrialized city in the Moravian-Silesian region (Czech Republic), as a case study to examine how these processes shape bryophyte diversity in an urban landscape. Between 2021 and 2024, we recorded 129 bryophyte taxa (18 liverworts, 111 mosses) within the Zoo, a species richness comparable to that of nearby protected areas in the Moravian-Silesian Beskids. The assemblage includes several regionally rare taxa and a pronounced epiphytic component (38 epiphytic species), indicating both improved air quality and the importance of old, healthy tree stands. Analyses of species occurrence across habitat categories demonstrate that the exceptional diversity of the Zoo is underpinned by high substrate and microhabitat heterogeneity, spanning remnants of beech forest, wetlands, disturbed soils in animal enclosures and a wide range of artificial structures. Back-trajectory modelling of air masses during the main vegetation season further shows that prevailing winds frequently connect the Zoo with bryophyte-rich reserves in the Beskids, supporting the hypothesis that the Zoo functions as a recipient and secondary source of diaspores in a fragmented urban matrix. Our results highlight that large urban green areas such as zoological gardens can act as bryophyte refugia and stepping-stone sites of conservation importance within industrial regions.