When you think of a forest, you might imagine towering trees, their ancient trunks reaching for the sky. Perhaps you envision birds nesting in their branches or moths making homes in their bark.

You might also picture the soft, lush moss coating the trunks, creating an ancient, almost mystical atmosphere. If you’re lucky, you’ve had the chance to rest on a bed of moss, feeling its comforting softness beneath you.

But beyond its beauty and comfort, have you ever wondered why moss—and other bryophytes—might be more important than we realize?

Mosses are the unsuspecting heroes of forests. Because bryophytes are so diverse, they contribute greatly to the biodiversity in forest ecosystems. They also play an important role in succession, nutrient fixation, water reservation, and preventing erosion. Despite their importance, they often remain overlooked in forest management, ecological planning, and biodiversity surveys.

Plagiothecium undulatum. Photo by Nils Cronberg

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Role of Bryophytes in Types of Forests

Forests can be broadly divided into three different types: boreal, temperate, and tropical. The role of bryophytes has primarily been studied in boreal and temperate forests, where their presence has been known to be vital for productivity. However, bryophytes are poorly studied in tropical forests, so their importance may be understated in current scientific literature.

Role in Succession

Bryophytes are key to primary succession because they can grow on substrates that are unfavorable to other land plants. By growing on the substrate, they contribute to soil formation and moisture accumulation, allowing other species to grow.

Hypnum cupressiforme. Photo by Nils Cronberg 

After disturbances such as fires and clear-cutting, bryophytes are among the first to grow on exposed soil. By binding water and fixing nutrients, they help repair the environment, allowing other plants the opportunity to grow (Glime, 2024).

Role in Water Balance

Bryophytes are vital for maintaining the water balance in forest environments. Although the amount of water absorbed by bryophytes differs depending on species, bryophytes can survive periods of drying out better than other species, so when it rains, they can sequester water and release it back into the environment, along with nutrients. Furthermore, they slow the water flow and allow more time for other plants to absorb it. As they absorb water, they also serve as a temperature regulator in the soil and surrounding environment (Glime, 2024).

Ptilium crista-castrensis. Photo by Nils Cronberg

Role in Nutrient Fixation

Many bryophytes harbor important fungi and bacteria that are important for fixing nitrogen, which is a nutrient often lacking in soil, especially in boreal forests. They also redistribute nutrients such as potassium and magnesium (Glime 2024).

Competition

Although bryophytes clearly serve many important roles, it is important to mention how bryophytes compete with other species, including trees. Due to their growth form, they can, in some cases, smother and prevent the emergence of tree seedlings. Despite their size, they also compete with trees for nutrients and send chemical signals that limit the growth and reproduction of trees! For example, as boreal forests age, when trees age or become stressed, bryophytes can begin to deprive the trees of nutrients, shifting the demographic towards bryophytes.

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Despite bryophytes’ clear role in forest communities, there is a deficit of studies exploring their complexity in these ecosystems. By understanding the role of each species in the forest, we can better understand how to conserve the world’s beautiful forests and all of their benefits.

Author: Eliza Hayse

References

Glime, J. M. 2024. Roles of Bryophytes in Forest Sustainability—Positive or Negative? Sustainability 16: 2359.