For the majority of humans, soil is often dismissed as mere dirt beneath our feet. However, groundbreaking research has unveiled that soil constitutes a crucial habitat for more than half of Earth’s species—a habitat that is currently under grave threat.

Mark Anthony, a fungal ecologist at the Swiss Federal Institute for Forest, Snow and Landscape Research and co-author of the study, emphasizes the emerging significance of soil: “I think soil’s having a moment. We’re starting to realize that we’ve really messed up our soils at a global scale.”

The study, recently published in Proceedings of the National Academy of Sciences USA, presents a remarkable revelation. It calculates that approximately 59 percent of Earth’s species rely on soil for one or more stages of their life cycle. This figure marks a stark departure from the previous general estimate of around a quarter of all animals. Anthony acknowledges his initial skepticism: “I did come in with expectations that the number would be way higher than everyone was saying because 25 percent felt low. It just felt wrong.”

To arrive at this groundbreaking insight, Anthony and his colleagues embarked on a comprehensive endeavor. They collated existing global estimates of overall species richness and soil biodiversity across the most populous life groups, encompassing bacteria, fungi, plants, insects, and mammals. This effort was not without challenges, given the vast knowledge gaps pertaining to certain groups and their intricate relationships with soil.

Diana Wall, a soil ecologist at Colorado State University, expresses her anticipation for such revelations: “It’s something I’ve been waiting for.” She commends the study’s approach and findings, emphasizing the current state of scientific understanding.

The research sheds light on the varying degrees of soil reliance within different groups. Among the investigated categories, potworms, or Enchytraeidae, stand out with an astonishing 98.6 percent reliance on soil. These creatures, akin to miniature earthworms, spend their entire lives within the soil. On the other hand, mammals exhibit the lowest soil reliance, with only about 4 percent depending on soil for specific life stages. Prairie dogs, for instance, nest underground, exemplifying this limited reliance. Plant species fall within the spectrum, with certain species like air plants thriving far from the soil’s reach.

The revelation that around 59 percent of species are dependent on soil for survival underscores its profound importance. While Anthony anticipates refinements in the exact figures as our understanding deepens, he emphasizes the paramount significance of recognizing the scale of soil reliance. He likens this discovery to a census, advocating for increased conservation and restoration efforts for this undervalued environment.

The study’s findings underscore the urgent need to prioritize soil preservation, recognizing its indispensable role in sustaining the intricate web of life on Earth.

By Impact Lab