How moss makes better soil and helps combat climate change

Mosses are one of the planet's most common – and undervalued – plants. A large new study has finally given moss the recognition it deserves, highlighting its importance in maintaining Earth’s ecosystems and its potential for reducing our carbon footprint.

Mosses are found everywhere, from deserts to arctic regions. Despite their ubiquitousness, mosses are often ignored in favor of vascular plants, whose role in improving the soil, maintaining plant diversity and ecosystems has been well-researched.

Vascular plants have both lignified (wood-like) tissues for transporting water and minerals throughout the plant and non-lignified tissue to aid in photosynthesis. By contrast, mosses are non-vascular plants, absorbing water and nutrients through their surface. Their roots are different, too, with growths called rhizoids anchoring them to the soil surface.

As their name suggests, soil mosses grow on the soil's surface. They’re also among the most widely distributed land plants, but how they influence ecosystems has rarely been studied. Now, the most comprehensive global field study of mosses undertaken, led by researchers at the University of New South Wales Sydney, has examined soil moss in its natural habitat to determine just how important it is to the planet.

“We were originally interested in how natural systems of native vegetation that haven’t been disturbed much differ from human-made systems like parks and gardens – our green spaces,” said David Eldridge, lead and corresponding author of the study. “So for this study, we wanted to look at a bit more detail about mosses and what they actually do, in terms of providing essential services to the environment.”

The researchers collected moss samples growing on soil from more than 123 ecosystems across the planet, from lush rainforests to deserts to icy landscapes. They found that mosses cover an incredible 3.6-million-square-mile (9.4-million-sq-km) area of the Earth, which is close to the size of Canada or China.

The researchers found that soil mosses benefit the soil and neighboring plants in 24 ways, including maintaining soil biodiversity, nutrient cycling, decomposition of organic matter, maintaining microbial populations and controlling soil pathogens.

“We looked at what was happening in soils dominated by mosses and what was happening in soils where there were no mosses,” said Eldridge. “And we were gobsmacked to find that mosses were doing all these amazing things.”

In addition, the researchers found that mosses are crucial to controlling climate-changing carbon dioxide. Globally, soil moss has the potential to draw 7.08 billion tons (6.43 billion tonnes) of carbon dioxide from the atmosphere compared to moss-less soil, they say.

“So you’ve got all the global emissions from land use change, such as grazing, clearing vegetation and activities associated with agriculture – we think mosses are sucking up six times more carbon dioxide, so it’s not one to one, it’s six times better,” Eldridge said.

Based on their findings, the researchers are urging people not to disregard the benefits of moss and to think twice before ripping it out of the garden.

“People think if moss is growing on soil it means the soil is sterile or has something wrong with it,” Eldridge said. “But it’s actually doing great things, you know, in terms of the chemistry of the soil, like adding more carbon and nitrogen, as well as being primary stabilizers when you get lots of disturbance.”

The researchers intend to continue their research to see whether mosses can rejuvenate soils in urban environments as well as they do in natural areas.

“We are also keen to develop strategies to reintroduce mosses into degraded soils to speed up the regeneration process,” said Eldridge. “Mosses may well provide the perfect vehicle to kick start the recovery of severely degraded urban and natural area soils.”

The study was published in the journal Nature Geoscience.

Source: University of NSW Sydney