What Do Tiny Worms Reveal About Our Urban Soils?

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Imagine starting your day in a quiet forest. The soil beneath your feet is soft, dark, and full of life — a bustling underground world of roots, fungi, and millions of microscopic creatures. Now picture walking slowly toward the city. Trees give way to lawns, lawns to sidewalks, sidewalks to streets. The soil hardens, the hum of life changes. But what exactly happens beneath the surface as the city takes over?

Nearly twenty years ago, soil ecologist Mitchell Pavao-Zuckerman set out to explore that very question. Together with colleague David Coleman at the University of Georgia, he followed a simple but powerful idea: if we trace the soil from the forests surrounding Asheville, North Carolina, all the way into the heart of the city, we might see how urban life reshapes the smallest forms of life — the nematodes, or microscopic roundworms that inhabit every handful of soil.

These tiny worms — actually beneficial nematodes and key players in soil ecosystems — are like voices in a hidden choir. Some feed on bacteria (bacterivores), some on fungi (fungivores), and some are predators — together, they form the micro–food web that keeps soil ecosystems running. By listening to their “song,” scientists can tell whether the soil community is healthy, stressed, or recovering.

After sampling soils along this urban–rural transect, Pavao-Zuckerman found something unexpected. The number of nematodes didn’t change much from forest to city — but their roles did. In the forest, the soil community was balanced: predators, decomposers, and recyclers all working together. In the city, the balance shifted. The tough, fast-growing nematodes — the ones that thrive on disturbance — took over. The sensitive ones, those that depend on rich organic matter and stable food webs, almost disappeared. It was like a symphony that had lost its softer instruments — louder, simpler, still active, but missing its full harmony.

This story is powerful because it shows that soil health is about more than just counting species. A soil may appear “healthy” when looking at biodiversity numbers alone, but the real measure lies in what those species are doing. Ecosystem functions — nutrient cycling, pest regulation, decomposition, and organic‑matter processing — can be compromised even when species counts seem high. By studying nematodes, we gain insight into the functional health of soils and see how urbanization shifts life beneath our feet.

The message was clear: urbanization reshapes soil life, not by erasing it, but by changing how it works. The soil’s microscopic orchestra was still playing — just in a different key. Today, that insight continues to inspire research and education efforts around the world. It reminds us that soil health is more than chemistry and texture — it’s a living system that mirrors the history and stress of its environment.

At nemaBiodiversity, we follow that same curiosity. By studying nematode communities across farms, gardens, and urban spaces, we can read the subtle stories of soil health and resilience. Every handful of earth tells a tale — and nematodes are its storytellers.

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This article summarizes and interprets findings from Pavao-Zuckerman & Coleman (2007) for educational and outreach purposes under fair dealing.

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—Further Reading

• Pavao-Zuckerman, M. A., & Coleman, D. C. 2007.Urbanization alters the functional composition, but not taxonomic diversity, of the soil nematode community. Applied Soil Ecology, 35, 588–595.