Soil biodiversity could counter negative health impacts of urbanization

Biodiversity is the variety of animals, plants, fungi, and microorganisms that gather in one area and work together to create an ecosystem that balances and supports life. In a new study, scientists from China, Europe and Australia have examined how urbanization has affected an often overlooked area of biodiversity, soil biodiversity, and how it has impacted human health.

It is anticipated that, by 2050, 70% of the Earth’s population will live in cities. The rapid urbanization of the planet poses a risk to biodiversity through the loss of green spaces and natural habitats, and increasing pollution. But another important environmental player is often overlooked as a contributor to biodiversity: soil.

“The potential for improving human health by enhancing soil biodiversity is an important yet little understood field of fundamental and applied research,” said Professor Xin Sun, who leads the Urban Soil Ecology Group at the Institute of Urban Environment at the Chinese Academy of Sciences and was the lead author in the study.

Soil contributes to human health in various ways: providing food for humans and animals, supplying important health-related resources like antibiotics and pharmaceuticals, and regulating the immune response in humans.

Unbalancing the soil-based ecosystem can lead to an increase in opportunistic bacteria and parasitic worms, increased greenhouse gas emissions, nutrient leaching, and reduced plant growth.

“Unfortunately, land management linked to urbanization, surface sealing, compaction, pollution and removal of vegetation can adversely affect soil biodiversity which traditionally have been one of Earth’s largest reservoirs of biological diversity,” says Dr Craig Liddicoat, a contributor to the study from Flinders University in South Australia.

An issue the researchers considered was the impact of soil biodiversity on immunity in humans. There is evidence to suggest that the reduced exposure to biodiversity that comes with city living may cause the immune system to be overly sensitive to things like dust particles and pollen.

They cited previous studies which showed that children who grew up on farms, compared to urban areas, had a reduced frequency of allergies. In particular, a long-term Finnish study of children in urban daycare showed that introducing plants and soil into daycare yards enhanced the growth of good bacteria and suppressed bad bacteria on the skin and in the guts of the children.

After examining the negative and positive links between soil biodiversity and human health, the researchers concluded that human health should be prioritized by conserving and restoring soil biodiversity in urban areas.

They also point to the added benefit that providing more parks, gardens and forests would have in fostering a sense of community.

“We need to revisit strategies to rebuild the quality and exposure to soils via restoration and work on more creative ways of greening and rewilding our cities to improve not only the environment, but also our own health,” said contributing author Associate Professor Martin Breed.

The study was published in NPJ Urban Sustainability.

Source: Flinders University via Scimex

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