Soil bacteria and fungi respond differently to urbanization

Urbanization is reshaping more than just skylines. As cities expand and natural landscapes give way to concrete and park lawns, the soil beneath our feet is changing too.

The diversity of life underground – especially among bacteria and fungi – is responding to the pressures of urban development in surprising ways.

New research now shows that, while bacterial communities are becoming more alike across cities, fungal communities are holding onto their unique identities.

This new study comes from scientists at Shanghai Jiao Tong University, the University of Helsinki, and other international institutions.

The researchers studied soil microbial communities in boreal, temperate, and tropical biomes. They looked at sites ranging from undisturbed forests to urban parks of various ages.

Their findings reveal a striking contrast in how bacteria and fungi have responded to urbanization.

Soil bacteria reshaped by urbanization

The researchers found that bacteria in urban soils tend to behave like generalists. They adapt quickly and can thrive in a range of conditions.

In fact, the similarity between bacterial communities rose from 79% in forests to 85% in younger urban parks. About 90% of urban soil bacteria were generalists.

Fungi, on the other hand, proved to be more resistant to change. Roughly 83% of fungi remained specialists – organisms that stick to very specific environmental conditions.

Their evolutionary pace is slower than that of bacteria and they don’t share genes as easily. This keeps them more rooted to particular niches.

“Urbanization is a powerful force reshaping soil microbial communities, yet bacteria and fungi respond in strikingly different ways. Bacteria swiftly adapt to urban conditions, whereas fungi retain their ecological specialization, highlighting the complex interplay between microbial adaptation and ecosystem resilience,” noted Dr. Nan Hui, the study’s corresponding author.

What makes bacteria and fungi different?

The contrasting responses of bacteria and fungi to urbanization stem from their fundamental biological differences.

Bacteria are single-celled organisms with relatively simple structures and rapid reproduction cycles. They readily exchange genetic material through processes like horizontal gene transfer, allowing them to adapt quickly to new or stressful environments.

Fungi, by contrast, are more complex. Many are multicellular, forming extensive underground networks known as mycelia. These structures connect them intimately to their surroundings, making them less mobile and less genetically flexible than bacteria.

Fungi also tend to evolve more slowly and rely heavily on specific environmental conditions and host relationships.

These inherent traits explain why bacteria can act as generalists in urban soils – adapting and thriving across varied settings – while fungi often remain tied to particular ecological niches.

Soil bacteria adapt to urbanization

Despite their different strategies, both bacteria and fungi are essential for the same big job: keeping the soil healthy. They break down organic matter and recycle nutrients.

The study shows that even though the fungi and bacteria populations shift differently, their shared functional traits help maintain these vital services in urban soils.

This redundancy in ecological roles means cities aren’t necessarily doomed to poor soil health. The resilience is built in. And that’s good news for city planners and environmental managers looking to protect urban green spaces.

It also suggests that microbial soil communities can adapt to disturbance without losing their core functions. With the right support, urban soils can continue to thrive – even in heavily modified environments.

The future of city soil resilience

Soil microbes are often overlooked in discussions about biodiversity, especially in cities. But this study makes it clear that they play a vital role in sustaining life above the surface. Understanding their behavior under the stress of urbanization is a step toward building more resilient cities.

Future research could explore how certain design choices – like the age of green spaces or the types of plants used – shape these microbial communities.

Microbial studies like this one are essential for designing urban environments that support biodiversity, climate resilience, and long-term sustainability.

The more we learn about what keeps urban soils alive, the better equipped we’ll be to nurture the ecosystems that support us – even in the heart of the city.

The full study was published in the journal Environmental Science and Ecotechnology.

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