Although most of the world's biodiversity is below ground, surprisingly little is known about how it affects ecosystems or how it will be affected by climate change. New research published this week demonstrates that soil bacteria and the richness of animal species belowground play a key role in regulating the way in which ecosystems function.

In Europe, experts have expressed deep concern over the lack of soil science research and protection for soils, which scientists class as a non-renewable resource due to the amount of time they take to build up. This week, researchers from the University of Copenhagen added their voices to calls for more attention to be paid to the overlooked underworld of worms, bugs and bacteria in the soil.

Ecosystem functions such as carbon storage and the availability of nutrients for crops are linked to the bugs, bacteria and other microscopic organisms that occur in soil. In fact, as much as a third of the variation seen in ecosystem functions can be explained by the biodiversity in the soil. Researchers estimate that plant biodiversity has only a slightly larger impact than soil biodiversity on how well an ecosystem functions.

Aimée Classen from the University of Copenhagen’s Center for Macroecology, Evolution and Climate, who co-authored a study which appeared in the journal Nature Communications this week, said, "Biodiversity below ground is neither very visible nor very cute, but pick up a handful of soil and you might find more species there than all of the vertebrates on the planet. We need to turn our attention towards these organisms, if we are to better understand the ecosystems we depend on for a range of functions.”

Classen’s study is unique in relating soil biodiversity to a whole suite of ecosystem functions rather than focusing on a few. These were combined in an index called ecosystem multifunctionality (EMF).

Dr. Xin Jing from Peking University, who also worked on the study, explained, “Ecosystems have multiple functions which are all important. They store carbon in soil and biomass which has massive implications for climate change, but they also hold back and release various nutrients which have effects on natural areas as well as agricultural yield. Therefore, we need to be concerned with the multiple functions of ecosystems, what controls them and how this might change with climate change.”

The study was carried out at 60 different sites of alpine grassland on the Tibetan Plateau in China which was chosen for its extensive variation in climate across sites. Even though rainfall, temperature and pH varied from place to place, the soil biodiversity always influenced ecosystem multifunctionality.

"The results suggest that the same pattern is likely to be found in other ecosystems around the world. However, our study also shows that the effect of soil biodiversity on ecosystem functions may be greater in areas with higher precipitation. That is important because scientific studies often focus on temperature - not precipitation - when predicting how ecosystems will respond to future changes such as climate change", added Professor Classen.