Moss is increasingly threatened on Earth due to disturbances such as livestock farming, overharvesting, land clearing, and even climate change, which are the greatest threats.
Like a lush green carpet rather than a forest or grassland, this humble species of moss possesses incredible power. No one believes that such a tiny plant can have such a significant impact on the Earth. In a remarkable recent study, researchers have uncovered the importance of this diverse group of plants for ecosystems around the globe.
Moss plays a vital role in ecosystems – (Image: Internet).
David Eldridge, an ecologist at the University of New South Wales, Australia, exclaimed: “We were absolutely amazed to discover that moss is doing all these wonderful things.”
Sampling moss from over 100 sites across 8 different ecosystems, Eldridge and his colleagues estimated the population of this plant species covers an astonishing area of 9.4 million km2 in the types of environments they surveyed. This figure is comparable to the size of China or Canada.
As the ancestors of all currently thriving plant species, these ancient organisms have a simpler structure compared to their descendants, with branches filled with small leaves, often just a single cell thick. But this does not diminish the greatness of moss in any way.
Eldridge stated: “Moss lacks the vascular system that regular plants have. But moss survives by absorbing water from the atmosphere. Some species of moss, like those in the arid regions of Australia, can curl up when they dry out without dying – they live in a long ‘dormant’ state. We have tested curled moss after 100 years, sprayed water on them, and watched them come back to life. Their cells do not decompose like those of regular plants.”
Moss lacks a vascular system that allows vascular plants to grow tall and draw water from below the ground. This keeps them relatively short and they develop a close relationship with the upper soil layers.
Moss has a high absorption capacity and can capture airborne particles. Some of these particles are incorporated into the soil below. It is no surprise that they have a powerful impact on the soil. Researchers compared moss-covered and bare soil in each of their study areas and found that nutrients moved more freely in mossy soils, enhancing the cycling of everything from nitrogen and phosphorus to organic matter. Notably, Eldridge’s team’s modeling suggests that globally, moss stores 6.4 gigatons more carbon than bare soil.
In other words, losing just 15% of the global moss-covered land would be equivalent to the global emissions of carbon dioxide from all land use in a year, such as deforestation and livestock grazing.
Eldridge explained: “You generate types of global emissions from land-use activities such as livestock grazing, clearing vegetation, and other agricultural-related activities. We believe that the area of land with moss is absorbing carbon dioxide six times that amount.”
Furthermore, the research team found that moss seems to suppress potential pathogens. Soil is a massive reservoir of soil-borne pathogens, but the soil beneath moss has a lower rate of plant pathogens. Surveys counted fewer potential plant pathogens in the soil where moss thrives, and antibiotic genes are extremely rare in the microbiome of moss environments compared to areas without vegetation. Moss may help reduce pathogen loads in the soil. This ability may stem from when moss evolved into terrestrial plants.
Eldridge and his colleagues hypothesize in their report: “We believe that the increased carbon content in the soil beneath moss may reduce the competition of microorganisms and the demand for them to produce antibiotic genes.”
The shallow root systems of moss help hold the soil together, creating a stable surface for the continuous growth of plants leading to more complex ecosystems. It can be predicted that long-lived moss species store more carbon in the soil and better control plant pathogens compared to short-lived moss.
After major disturbances like volcanic eruptions, moss is one of the earliest organisms to return and thrive, just after cyanobacteria and algae.
Not All Moss is the Same
The high density of moss carpets and species such as Sphagnum, Hylocomium, and Ptilium contributes most to soil biodiversity and ecosystems, especially in tree-less areas like deserts and tundras.
The ability of moss to support ecosystems or a diverse community of bacteria, fungi, and invertebrates is strongest in sites with abundant carpet and grass-like moss such as Sphagnum, which is widely distributed in northern forests.
Sphagnum has the most positive impact on the diversity of bacteria, fungi, and invertebrates and also provides nutrients in the food chain.
Some moss species wrap around stems to reduce sun exposure.
Moss from the Pottiaceae family is particularly well-suited to survive in dry and harsh conditions. Many species have special structures that allow them to endure water scarcity. They have boat-shaped leaves with long hairs that help channel water to the center of the plant. Some moss species wrap around stems to reduce sun exposure and conserve moisture.
Desert moss also protects the soil from erosion, affects the amount of water moving through upper layers, and even alters the survival chances of seedlings.
Protecting Moss
Eldridge concluded: “What we show in our study is that where you have moss, you have better soil health, such as more carbon and nitrogen. Moss can provide a perfect means to kickstart the restoration of urban and severely degraded natural areas.”
Overall, Eldridge’s team’s research shows that moss impacts critical soil processes and operates similarly to vascular plants. Their impact may not be as strong, but the entire cover of moss is significant when considering the global scale.
However, moss is increasingly threatened on Earth due to disturbances from livestock farming, overharvesting, land clearing, and even climate change, which are the greatest threats.
We need greater recognition of the benefits that moss provides to all life on this planet. This means more education about their positive benefits, identifying and mitigating the main threats they face, and incorporating them into regular monitoring programs.
Moss is found everywhere, but its future is not guaranteed. They have the potential to play an increasingly important role as vascular plants decline under predicted hotter, drier, and more variable global climate conditions.
