12 March 2024

Diversity of soil microbes increases with climate change

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A study from the University of Vienna brings new insights into the microbiome-climate cycle in the soil. Higher temperatures activate dormant bacteria, scientists explain

by Matteo Cavallito

 

Higher temperatures stimulate greater diversity in the population of soil microbes. A phenomenon that suggests a rethinking of the most common hypothesis about the link between climate change and the growth of microorganisms. This is revealed in a new study conducted by researchers at the Centre for Microbiology and Environmental Systems Science (CeMESS) at the University of Vienna.

“Until now, scientists have assumed that higher soil temperatures accelerate the growth of microbes, thus increasing the release of carbon into the atmosphere,” says a statement from the Austria-based university. “However, this increased release of carbon is actually caused by the activation of previously dormant bacteria.”

The interaction between microbes, climate and soil

“Soils are Earth’s largest reservoir of organic carbon,” says Andreas Richter, lead author of the study. And dictating the carbon cycle, the authors continue, are microbes breaking down organic matter and releasing CO2. These emissions increase as temperatures rise, thus accelerating global warming in a continuous interchange between climate and soil.

However, the study says, “Existing knowledge about microbial responses to warming is based on community-level measurements, leaving the underlying mechanisms unexplored and hindering predictions.”

The study

“For decades, scientists have assumed that this response is driven by increased growth rates of individual microbial taxa in a warmer climate,” Richter explains. But is this really the case? To find out, the researchers examined a subarctic grassland in Iceland that had been subject to geothermal heating for more than half a century.

By collecting deep soil samples, “we investigated how active populations of bacteria and archaea responded to elevated soil temperatures (+6°C) and the influence of plant roots,” the scientists explain.

Using specific analysis techniques allowed the authors to measure the growth rates of each microbial species. Thus reaching new conclusions. “Contrary to prior assumptions, increased community growth was associated with a greater number of active bacterial taxa rather than generally faster-growing populations,” the study reads. “We also found that root presence enhanced bacterial growth at ambient temperatures but not at elevated temperatures, indicating a shift in plant-microbe interactions.”

Predicting microbial activities

The results of the study thus highlight the importance of analyzing the diversity of microorganisms in order to fully understand the more complex mechanisms governing the relationship between climate and soil. In-depth studies, therefore, could allow for a better examination of this relationship, thus enabling to make trend predictions in the future.

The response of the soil microbiome to climate change has always been a “‘black box in climate modeling,” says Christina Kaiser, professor and co-author of the study. “This new finding transcends the traditional focus on community-aggregated growth, setting the stage for more accurate predictions of microbial behavior and its consequent effects on carbon cycling in the evolving climate scenario.”