Unmanicured urban green spaces and natural surfaces in children’s play environments provide more diverse microbial exposure in urban areas
Two recent studies show that natural surfaces and unmanicured green areas in urban environments can increase microbial diversity while also promoting beneficial microbial exposure for citizens. Both the management practices of green spaces and the surface materials used in playgrounds influence the types of bacterial communities that urban environments can host.
Less maintenance, more microbes: comparing urban green spaces in Finland and Tatarstan
The first study compared surface soil microbiota at the entrances of urban parks in Finland and Tatarstan (Russia). All the samples were collected before COVID-19 pandemics and the Ukraine war. The aim of the study was to investigate whether the diversity of bacterial communities in urban green spaces differs between countries with contrasting socioeconomic backgrounds and significantly different prevalence of immune-mediated diseases. Previous research has indicated that people in Russian Karelia are exposed to a more diverse environmental microbiota, which may protect against immune-mediated diseases. However, differences between countries had not been investigated from the perspective of urban green parks, even though parks are the most important sources of natural microbiota for citizens.
The results were clear: the surface soil microbiota at the entrances of Tatarstan urban parks was significantly more diverse compared to Finnish ones. The differences were explained by the level of unmanicured areas and the associated increase in organic matter in the surface soil. The findings suggest that benign neglect, shifting from intensively mowed lawns and heavily maintained parks toward lighter maintenance, could enhance microbial diversity, including microbes linked to human health. Such an approach could also provide more cost-effective green space management solutions for cities.
Artificial surfaces reduce microbial diversity in children’s play environments
The second study focused on the surface materials used in children’s play environments. Previous research has shown that soils rich in organic matter host abundant and diverse microbial communities, making direct comparisons with rubber mats less meaningful. Instead, the study selected two surfaces with similar characteristics, specifically hard and dry surfaces actively used by children: artificial rubber mats and natural rocks.
The study found that natural rock surfaces hosted higher bacterial abundance and diversity than artificial rubber mats. One of the most interesting findings was that although bacterial abundance and diversity were lower on rubber mats, the bacteria formed significantly more interconnections with other bacteria on these surfaces. Previous research suggests that such complex networks arise in stressful environments, where bacteria develop symbiotic and interdependent relationships to survive. The results support the view that human-made artificial surfaces, such as rubber mats in children’s play environments, create more challenging environments for natural microbial communities.
Both studies point in the same direction: natural and unmanicured urban environments support microbial diversity far better than artificial or intensively managed areas. Diverse microbial communities not only enhance ecosystem services in cities but also provide health-beneficial microbial exposure to citizens.
