Microbes are the ‘active engineers’ in the earth’s rock-to-life cycle

The name “critical zone” may conjure up pleasant thoughts of the 1980s, but it is a term that scientists use to refer to the area of ​​the earth responsible for sustaining life. A relatively small part of the planetary system, it extends from the rock beneath the earth’s surface to the lower atmosphere.

“Think of it as the skin of the Earth,” said Jon Chorover, head of the Department of Environmental Sciences at the University of Arizona College of Agriculture and Life Sciences. “Sometimes it’s called the place where rocks meet life.”

Most people—even geologists—don’t think about rock as the basis for life or how life can change rock, but that gets to the heart of important science, Chorover said.

A new framework for approaching the global sciences, the key area connects researchers across disciplines to better understand how the delicate web of physical, chemical and biological processes intertwine. creating Earth’s life system.

As a biogeochemist, the whole-systems approach is a way of thinking that comes naturally to Chorover, who has spent much of his career working to unravel the ways in which chemical and mineral weathering drives material change. each from the soil microbiome to carbon. circuit.

Together with Qian Fang, a postdoctoral researcher from Peking University in Beijing, Chorover recently published the results of nearly 10 years of data collected at the Santa Catalina-Jemez River Basin Critical Zone Observatory—covering altitude and climate. on the rocks. northern New Mexico and southern Arizona.

Their findings, according to Chorover, provide a “smoking gun” between the activities of carbon-eating microbes and the transformation of rock into soil that sustains life in an important area.

An open, living laboratory

In the past, measuring something like the weathering of minerals was often less interesting—think researchers breaking up rocks and watching them dissolve in beakers back in the lab. But looking at that process in a natural ecosystem is a different story.

At the Santa Catalina-Jemez River Basin Critical Zone Observatory, towers that measure the exchange of water between the forest and the atmosphere, soil instruments that measure the transfer of energy and gases, and many other environmental instruments give scientists a view of see. of complex systems within a critical domain.

The site is part of the National Science Foundation’s larger Critical Zone Observatory program, which instead of traditional brick-and-mortar sites provides a network of scientifically-equipped ecosystems across the United States.

Temperature, humidity and gas sensors on site collect measurements every 15 minutes, and after collecting and correlating the data, “What we found was a strong correlation between speed that the rock was heated to create soil and microbiome activity underground,” said Chorover, principal investigator at the Catalina-Jemez observatory.

Breaking the rock-to-life cycle

“Minerals, microbes and living things are some of the most important elements on earth,” Fang said. “They constantly work together to provide all life on earth with nutrients, energy and suitable habitats.”

These precious minerals are constantly attacked by microbes, organic acids and water, Fang explained. As minerals break down, microbes in the soil consume the new organic matter and turn it into nutrients for plants and other organisms, while releasing carbon dioxide.

Previous studies suggest that microbial decomposition of soil organisms can be enhanced when other “new” organisms – such as plants – are introduced into the soil system. This process is called the “priming effect” by soil experts. However, the relationship between mineral weathering and microbial priming remains unclear.

“Our research shows, for the first time, how these important soil processes are linked, and these two processes continue to influence soil structure, CO.₂ Emissions and global climate,” Fang said. “The relationships can be linked to long-term mobility and the rapid transformation of carbon and nutrients in the world.”

While it’s easy to see the flourishing of plants and microbes as fortunate environmental conditions, Chorover says this study proves that even the smallest parts of an important landscape have a big role to play. .

“It shows that life is not just a passive passenger in evolution, but actually an active engineer in determining the direction and direction of how the Earth’s crust changes,” Chorover said.

The work is published in the newspaper Nature Communication.