A study published in Science Advances has found that despite being an artificial ecosystem, city parks have a positive impact on our health and the surrounding environment.

Titled ‘Global homogenization of the structure and function in the soil microbiome of urban greenspaces’, the study involved taking soil samples from different types of urban green spaces and comparable neighbouring natural ecosystems in 56 cities across the globe, the study discovered that even roadside verges are beneficial to our wellbeing.

With 68 percent of the global population set to live in cities by 2050, the study suggests that urban green spaces are critically important for promoting mental and physical wellbeing. The study found that urban green spaces from all over the world, including the Beijing Olympic Park, the University of Queensland campus in Brisbane and Retiro in Madrid Spain are very similar.

The study’s Co-author, Professor David Eldridge from the Centre for Ecosystem Science in UNSW Science’s School of Biological, Earth and Environmental Sciences, says parks play a more important role in the health of the wider environment than one might expect.

“Parks are not the homogenised ecological deserts that we think they are – they are living ecosystems that do amazing things,” he says.

“Urban greenspaces harbour important microbes, so if you want to sustain a bunch of ecosystem services, you need to have plenty of parks and green spaces.”

The urban greenspaces studied included Olympic Park in Beijing, the University of Queensland campus in Brisbane, Retiro in Madrid Spain, and the park surrounding Uppsala Castle in Uppsala, Sweden.

Parks and gardens play important roles in curbing pollution, reducing noise, and lowering air temperatures, as well as providing recreational space in our cities. Moreover, human exposure to soil microbes has been shown to be beneficial to human health by promoting effective immunoregulation functions and reducing allergies, with green spaces supporting fast-growing microbes that use fertilisers and irrigation water, and that can colonise bare soils.

On the other hand, the study discovered that many green spaces around the globe harbour a greater proportion of fungal parasites and plant pathogens that are often economically important pests. Green spaces in some countries also host microbes that were linked to human pathogens, such as listeria and diphtheria.

“The really interesting thing is that there was a strong link between a country’s Gross Domestic Product and the abundance of the microbes that caused human diseases,” Eldridge says.

“One of the reasons could be a greater use of antibiotics in developing nations, and therefore greater microbe controlled antibiotic resistance. Sewerage water containing antibiotics is then used to water greenspaces. So while parks are good, there is a warning that some of the soil in these urban green spaces do harbour some of these toxic microbes, particularly in poorer cities.”

Eldridge says the discovery of the benefits of roadside verges is not as big of a surprise as some might think.

“We think of roadsides as being barren, but we found a great variety of different microbes in some roadside verges; they are not barren wastelands at all. Some European cities such as Bern in Switzerland have a policy to protect the natural vegetation along footpaths and roadsides. These pathways then become mini-green spaces, linking larger green spaces. We need lots of different microbes, and to get this, we need a variety of landscapes such as median strips, parks, and nature reserves.”

The international study is part of a series of research looking at the importance of green spaces for ecosystem health. The next study will examine the importance of mosses in urban green spaces for supporting healthy soils and important habitat for microbes.

Jarrod Reedie

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