Biodiversity flourishes in treetops, the deep sea and on coral reefs - but nowhere is it teeming with species like beneath our feet. Soils are the world's most species-rich ecosystem, reports a research team from Switzerland in the "Proceedings" of the US National Academy of Sciences ("PNAS"). The researchers estimate that 59 percent of all known species live there, and not just 25 percent as previously thought.
For example, the team points to springtails, a primordial form of six-legged creatures that are not classified as insects. These include Holacanthella spinosa, which is up to 17 millimeters long and is found in New Zealand, or Dicyrtomina minuta, which is only one or two millimeters long, spherical in shape and pale golden in colour. Springtails contribute to the formation of humus in the soil. Many of them have a jump fork on their body and can jump out of the dust when danger approaches.
The team looked at bacteria, viruses, fungi and a number of other creatures. Many of these are important for nutrient cycling or carbon storage. Others are pathogens or partners of the trees. According to estimates, only 3.8 percent of all known species of mammals live in the soil. But it's 90 percent for fungi, 86 percent for plants and their roots, and around 20 percent for molluscs like snails. The assessment of bacteria and viruses is difficult, write lead author Mark Anthony from the Swiss Federal Institute for Forest, Snow and Landscape Research WSL in Birmensdorf and colleagues.
Study should contribute to better soil protection
They did not dig for the study themselves, but combed through the specialist literature, as the WSL reports. Researchers from the University of Zurich and the agricultural research institute Agroscope were also involved in the study. There are often large gaps in knowledge, they write. The percentage of bacteria living in the soil ranges from 25 to 88 percent, depending on the region. Your study is only a first attempt, further research is needed.
The study is intended to contribute to decisions about better soil protection. "Soils are under tremendous pressure, be it from agricultural intensification, climate change, invasive species and much more," the WSL quoted Anthony as saying. "Our study shows that the diversity in the soil is large and correspondingly important and that it should therefore be given much more consideration in nature conservation."