More like a green carpet than a forest or pasture, the humble moss has incredible strength for such a small plant. In a surprising new study, researchers have discovered how important this diverse group of small herbaceous plants is to ecosystems around the world.

“We were stunned to see that algae do all these wonderful things,” says ecologist David Eldridge of the University of New South Wales in Australia.

After sampling algae from more than a hundred sites in eight different ecosystems, Eldridge and colleagues estimated that plant populations covered an astonishing 9.4 million square kilometers in the habitat types studied. This is comparable to the size of China or Canada.

These ancient organisms, the ancestors of all modern living plants, have a more simplified structure than their more modern descendants; twigs are full of small leaves, usually only one cell thick. But that doesn’t make them any less powerful.

“Algae don’t have the water pipes that a normal plant has, called xylem and phloem, to transport water,” says Eldridge.

“But the algae survives by collecting water from the atmosphere. And some algae, like those found in arid regions of Australia, curl up when they dry but don’t die – they stay suspended forever. After 100 years, we took the algae out of the bag, sprinkled them with water, and watched them regenerate. It doesn’t fall apart like that.”

The researchers compared mossy and mossy-free soils at each of the study sites and found that nutrients move more through the mossy soil, increasing the cycling of everything from nitrogen and phosphorus to organic matter. The algae also acts as a storage reservoir for nutrients, including carbon, which now holds about 6.43 billion metric tons of this vital but currently problematic element from our supersaturated atmosphere.

“You have all the global emissions from land use changes, such as animal grazing, vegetation clearing, and agriculture-related activities,” Eldridge explains.

“We think algae absorbs six times more carbon dioxide, so it’s six times better, not one to one.”

Moreover, the team discovered that algae harbor potential pathogens. Studies have found fewer potential plant pathogens in mossy soils, and incredibly antibiotic-resistant genes were less common in the microbiomes of mossy habitats than in plant-free areas.

“We believe that increased soil carbon under mosses may reduce microbial competition and the need to generate antibiotic-resistant genes,” Eldridge and colleagues write in their paper.

The shallow root balls of mosses help hold the soil together, provide a stable surface for successive plant growth, and result in more complex ecosystems. Algae also helps maintain the surface microclimate.

High-density wicker and turf mosses such as Sphagnum, Hylocomium and Ptilium contribute the most to soil biodiversity and ecosystems, especially in tree-free areas such as deserts and tundra.

And after major disturbances such as volcanic eruptions, one of the first organisms to return, after cyanobacteria and algae, is algae.

“We showed in our research that where there is algae, you have better soil health, as more carbon and nitrogen,” Eldridge said.

“Mosses can be an ideal tool to initiate the restoration of severely degraded urban and natural soils.”

This research was published in Nature Geoscience.