Bacterial communities are poorer at urban park entrances in Finland than Russian Tatarstan – Testing the core presumption of the biodiversity hypothesis

Urban green spaces are known to host diverse microbiota and provide beneficial ecosystem services for humans. Several studies have shown that exposure to environmental microbiota is lower among urbanites in Western lifestyle countries than in the former Eastern bloc, which has been linked to differences in lifestyle and urban environmental factors. Surprisingly, no studies have yet investigated whether urban green spaces host similar microbiota between countries which have different socio-economical backgrounds. To fill this gap, we sampled surface soil microbiota at urban park entrances in four cities with similar climates in Finland and Russian Tatarstan. We hypothesized to find richer and more diverse microbiota, core microbiome, and indicator species assemblage in Russian Tatarstan. We also hypothesized that park maintenance practices are different between the two countries, which is connected to soil microbiota. The results confirmed all the hypotheses and since we evaluated park characteristics, we were able to connect the observed differences to park management practices. Switching from intensively manicured green surfaces to non-manicured and benign neglect may favor richer microbiota, including those connected to human health. • Urban green spaces are important sources of environmental microbial exposure for citizens. • Urban park bacteriota varies between countries with differing socio-economic cultures. • The bacteriota was more diverse in Russian Tatarstan urban park entrances. • Finnish urban park entrances indicated more challenging conditions for bacteriota. • Unmanicured urban parks may increase the diversity of environmental microbiota.