Although previous findings suggest that soil microbes possess adaptability to climate change, a new study reveals that these organisms - which exert a huge influence over Earth's carbon cycle - may not be as effective at this process as previously believed.
When carbon is stored in soil, it is essential for bacteria, fungi and other microbes to convert it into carbon dioxide and other gases, expelling them into the atmosphere and keeping environmental changes in effect.
"Soil is the major buffer system for environmental changes, and the microbial community is the basis for that resilience," said author Vanessa Bailey of the Department of Energy's Pacific Northwest National Laboratory. "If the microbial community is not as resilient as we had assumed, then it calls into question the resilience of the overall environment to climate change."
The team came to their conclusions by examining two sets of soil stemming from a 17-year study on transplanting soils on a mountain in eastern Washington state and comparing them to controls. During the course of the study, some samples were moved to a warm, dry climate, whereas the others were moved to a cool, moist climate.
The microbes in the two experimental soil samples were analyzed in terms of their make-up, enzyme activity and respiration rates. The results showed less adaptability than expected.
The microbial make-up of the samples remained almost unchanged, and the microbes in both of the samples possessed many of the same traits that they exhibited in their "native" climate, including their original rate of respiration, suggesting that they did not properly adapt to the climate change they experienced.
Despite the surprise of the findings, the team makes it clear that these results don't mean that all microbes will respond in the same way.
"We can't assume that soils will respond to climate changes in the ways that many scientific models have assumed," said study co-author and Joint Global Change Research Institute scientist Ben Bond-Lamberty, although he admitted that "the fact that the soils' native environment continued to exert profound influence on microbial activity 17 years later is quite surprising."
Our current changing climate will expose microbes to new environmental conditions, making further research into this topic necessary to determine just how effective various microbes will be at dealing with these changes and the effects that these coping skills will have on Earth's ecosystems.
"With our changing climate, all microbes will be experiencing new conditions and more extremes," said Bailey. "This study gives us a glimpse of how microbes could weather such changes under one set of conditions. They may be constrained in surprising ways."
The findings were released in the March 2 issue of PLOS One.
