Climate change is taking its toll on mites and springtails, according to new analysis

They are invertebrates that live on land, but in a sense, they are the true backbone of the Earth’s carbon cycle.

Thousands of species of mites and springtails, living in soil around the world, provide a crucial service by chewing up organic matter like fallen leaves and wood, transferring their planet-warming carbon to the soil, and releasing nutrients that help new ones grow. floors.

But now, a new analysis combining data from 38 different studies on the organisms suggests that drought in some parts of the world, often burdened by climate change, is killing them at an alarming rate.

“It’s important to take care of these particular bugs because we know so little about them,” said Ina Schaefer, a soil invertebrate ecology researcher at the University of Göttingen in Germany.

While some of these organisms live deep in the soil, others spend most of their lives sneaking around on the surface. Scientists don’t understand exactly how they break down decaying organic matter, but new molecular research shows that springtails actually have special genes for this job.

(That’s not their only talent: Some springtails are the size of a grain of sand and can launch themselves into the air like circus acrobats, spinning up to 500 times a second. Scientists think it could be a way to escape predators.)

Mites and springtails have not been widely studied, despite their importance, but scientists do know that some of the soft-bodied creatures are very sensitive to the humidity of their environment.

When the soil dries out during dry times, they too can dry out, wither and die. On average, their populations decline by a whopping 39 percent during long periods without rain, according to the analysis, which was published this month in Global Change Biology.

And the more severe the drought, the more severe the reduction in their abundance will be, said Philip Martin, a researcher at the Basque Center for Climate Change in Leioa, Spain, and one of the study’s lead authors. In extreme conditions, “a lot more than that 39 percent figure is lost,” Dr. Martin said.

Previous research has indicated that the abundance of springtail populations is largely related to heat. Every degree Celsius increase in temperature corresponds with a drop in springtail populations of almost 10 percent, according to a 2023 analysis.

“They’re really doing poorly,” Gerard Martínez-De León, a doctoral candidate in terrestrial ecology at the University of Bern in Switzerland, said of springtails during heat waves. “If there are very high temperatures for, say, a week, two weeks, a month, this affects them directly. “Probably as much as the lack of humidity.”

Droughts also change and reduce populations of soil-dwelling fungi, according to research published in January, which is what springtails predominantly feed on.

However, there are some factors that work in favor of the soil’s inhabitants.

Mites generally do better in heat than springtails, and studies suggest that some species of springtails handle heat and dryness better than others. When times get tough, some invertebrates will go deeper into the soil or travel to wetter places in their environment, for example, under a rock. And others will adopt new diets and modify their preferences.

And the effects of climate change are not the same around the world. A temperature increase of, say, 4 degrees Celsius and a decrease in soil moisture by 20 percent will have a different effect in a mid-latitude desert, a high-latitude peat bog or a tropical forest, according to expert Zoë Lindo. in soil biodiversity at the University of Western Ontario. Her research has shown that different combinations of heating and wetting, and drying and cooling affect soil communities differently.

“Many different components interact in constantly changing ways,” Dr. Lindo said, and they all affect “the richness, abundance and composition of soil biodiversity, all at the same time.”

It’s also important to note that while some areas will experience more drought as the climate changes, others are expected to see heavier rainfall.

There are more than 12,000 known species of oribatid mites and about 9,000 species of springtails, but scientists believe those numbers may represent only 20 percent of their global species richness.

That lack of information could be the biggest problem facing soil invertebrates. More than half of the planet’s biodiversity is found under our feet. In addition to mites, which are arachnids, and springtails, which used to be classified as insects but now have their own group called springtails, there are about 430 million species of bacteria, almost 6 million species of fungi, and approximately 20,000 types of worms. on earth.

But there is a dearth of data for several large areas of the planet. Because we don’t fully understand how each species contributes to the ecosystem, we don’t know what could happen if we lose them.

“The soil has been like a black box,” said Leticia Pérez-Izquierdo, a terrestrial ecosystems researcher at the Basque Center for Climate Change in Spain who worked on this month’s study. “And now we’re starting to open it up.”

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