They’re invertebrates that live in the dirt, but in a sense, they’re the real backbone of Earth’s carbon cycle.
Thousands of species of mites and springtails live in soils around the world, providing a vital service by chewing organic matter such as leaf litter and wood, transferring planet-warming carbon into the soil and releasing nutrients that help new plants grow.
but now, New analysis Combined data from 38 different studies of these creatures show that droughts in parts of the world, often driven by climate change, are wiping out the creatures at an alarming rate.
“It’s especially important to look after these organisms because we know so little about them,” said Ina Schaefer, a soil invertebrate ecology researcher at the University of Göttingen in Germany.
While some microbes live deep in the soil, others spend most of their lives wandering around on the surface. Scientists don’t fully understand how they break down decaying organic matter, but New molecular study shows springtails Actually has special genes for the job.
(That’s not their only talent: Some springtails are the size of grains of sand and can Take to the air like a circus acrobatspinning 500 times per second. Scientists think this may be a way to escape predators.)
Despite their importance, mites and springtails have not been extensively studied, but scientists do know that some soft-bodied organisms are very sensitive to moisture in their environment.
When soil dries out during dry periods, they too dry up, shrivel and die, with their numbers slumping by 39 percent on average during extended periods without rain, according to the analysis. Published this month in Global Change Biology.
The more severe the drought, the greater the decline, said Philip Martin, one of the study’s lead authors and a researcher at the Leo Abasque Climate Change Centre in Spain. In extreme conditions, “the loss is much more than the 39% figure,” Dr. Martin said.
Previous studies have shown that springtail populations are closely linked to high temperatures: for every 1 degree Celsius increase in temperature, springtail populations drop by nearly 10 percent. According to the 2023 analysis.
“They are in real trouble,” Gerard Martínez-De León, a doctoral student in terrestrial ecology at the University of Bern in Switzerland, said of springtails during heat waves. “If the heat lasts for a week, two weeks or a month, it will directly affect them. It can be as bad as a lack of water.”
Drought can also alter and reduce the abundance of fungi in the soil. Research published in Januarywhich is also the main food of springtails.
However, there are some factors that work in favor of soil organisms.
In general, mites fare better than springtails in hot weather, research shows Some springtail species are better than others When the going gets tough, some invertebrates dig deeper into the soil or head for wetter areas around them, like under rocks. Others pick up new diets and adjust their preferences.
And the impacts of climate change will not be the same around the world. A 4-degree Celsius temperature increase and a 20 percent drop in soil moisture will have different effects on a mid-latitude desert, a high-latitude peatland or a tropical forest, says Zoë Lindo, a soil biodiversity expert at the University of Western Ontario. research shows Different combinations of warming and wetting, and drying and cooling, affect soil communities differently.
Dr Lindo said: “Many different components interact in constantly changing ways” which all “simultaneously influence the richness, abundance and composition of soil biodiversity”.
It is worth noting that with climate change, some regions will experience more droughts, while other regions are expected to experience more abundant rainfall.
There are more than 12,000 known species of oribatid mites and more than 9,000 known species of springtails, but scientists think these numbers may represent only 20% of the global species richness.
Lack of information is perhaps the biggest problem facing soil invertebrates. More than half of Earth’s biodiversity is Somewhere beneath our feetIn addition to mites (which belong to the class Arachnida) and springtails (once classified as insects but now in their own class, called springtails), soil is home to about 430 million species of bacteria, nearly 6 million species of fungi, and about 20,000 species of worms.
But data are scarce for many large areas of the planet, and because we don’t fully understand how each species contributes to an ecosystem, we don’t know what would happen if we lost them.
“Soil is like a black box,” said Leticia Pérez-Izquierdo, a terrestrial ecosystems researcher at Spain’s Basque Center for Climate Change, who was involved in this month’s study. “We are now starting to open it up.”
