8 May 2023

Mosses are an amazing ally for soil health


The University of New South Wales study: mosses promote nutrient accumulation in the soil and carbon sequestration. In degraded areas, moreover, these plants accelerate the regeneration process

by Matteo Cavallito


Mosses are among the most underrated plants on the Planet. Yet they retain a crucial role in protecting soil health, laying the foundation for plant flourishing in ecosystems and contributing to climate change mitigation through carbon sequestration. This is supported by a study conducted by the School of Biological, Earth & Environmental Sciences at the University of New South Wales in Sydney. The investigation, published in the journal Nature Geoscience, was based on the collection of samples from 123 ecosystems around the world and quantified the presence of these plant species on a global scale.

In the observed environments, the researchers remark, the specimens cover 9.4 million km2 of land, an area comparable to that of Canada or China. “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,” explained David Eldridge, professor and co-author of the study in a note released by the Australian university. “We were gobsmacked to find that mosses were doing all these amazing things.”

Mosses are a valuable resource

Unlike vascular plants, mosses have root-like outgrowths called rhizoids, used to anchor themselves to the soil surface, and survive by collecting water from the atmosphere. Some species, such as those found in arid areas of Australia, are able to preserve themselves in a “suspended” state indefinitely without their cells disintegrating as would happen to normal plants.

The fact, Eldridge goes on to explain, is that without mosses, ecosystems would face serious difficulties, being deprived of fundamental services. These species, in particular, contribute to the accumulation of essential elements in the soil such as carbon and nitrogen, and help keep the soil itself tight. Therefore, the loss of mosses as a result of deforestation results in nutrient leakage, also producing erosion and “destabilizing the whole system.”

The research

The survey, the authors explain, represents the first attempt to quantify the contribution of soil mosses in providing eight ecosystem services associated with 24 functional attributes. This makes it possible to assess how and how much these plants contribute to biodiversity and soil functionality on a global scale.

“We found that soil mosses are associated with greater carbon sequestration, pool sizes for key nutrients and organic matter decomposition rates but a lower proportion of soil-borne plant pathogens than unvegetated soils,” the study states.

In detail, the research continues, “soil mosses potentially support 6.43 Gt more carbon in the soil layer than do bare soils.” Moreover, “The amount of soil carbon associated with mosses is up to six times the annual global carbon emissions from any altered land use globally” This level is comparable to the amount of carbon released into the atmosphere due to practices such as deforestation for agricultural expansion and overgrazing. The largest contribution is found in the least productive ecosystems and on sandy and saline soils.

Crucial to the restoration of soils

Among the most significant aspects to emerge from the study is the ability of the plants observed to help restore damaged ecosystems. The researchers analized the area around Mount St Helens volcano in Tasmania, which recorded a devastating eruption in the 1980s. They observed how mosses were among the first life forms to reappear.

“Where you have mosses you have a greater level of soil health, such as more carbon and more nitrogen,” Eldridge explains. “So they’re helping to prime the soil for the return of trees, shrubs, and grasses, that eventually end up getting out-competed in the process. So they’re the first guys that get in there and fix things up and then first to leave.”

This opens the way for new research into the ability of these plants to recreate healthy soils.  Not only in natural areas but also in urban settings. Where the introduction of mosses could accelerate the restoration of degraded soils.