Global Warming Affects Soil Microbe Survival: Changing Climate Impacts Farming

First Posted: Jun 28, 2013 11:31 AM EDT

When it comes to global warming, a lot of attention is given to charismatic megafauna like polar bears and whales. Yet rising temperatures could have even more drastic consequences for a smaller creature which could, in turn, drastically affect us. Scientists have discovered that temperature determines where key soil microbes can thrive, which could affect farming practices in the future.

In order to learn exactly how climate change might affect microbial communities, researchers conducted continental-scale surveys of the microbial communities that live in soil crusts. They collected samples from Oregon to New Mexico and Utah to California. They then sequenced the DNA of these microbes in order to study them further.

In a single pinch of soil crust there are thousands of microbes. Yet two species in particular are the most common--cyanobacteria. These bacteria are capable of photosynthesis and without them, the other microbes simply wouldn't be able to exist. The cyanobacteria provide food and energy for the others, forming the "plants" of their system.

The two species are known as M. vaginatus and M. steenstrupii. Both can be found in different locations, affecting the composition of the soil depending where they happen to be. While they look similar, though, these two species are not very closely related. That said, they appear similar since they evolved their shape and behavior to help stabilize soil and form soil crusts.

Yet temperature can drastically affect these microbial communities, changing them for better or for worse. In order to see how climate changes might affect this composition, the researchers considered data about soil types and chemistry, rainfall, climate and temperature. More specifically, they created a mathematical model that showed temperature and explained the separation of M. vaginatus and M. steenstrupii. While M. vaginatus dominate crusts in cooler deserts, the other cyanobacteria dominate southern deserts.

So what does this mean exactly? As temperatures continue to warm, it's likely that the cooler temperature microbe will be pushed off of the map by the one that's better adapted to hotter temperatures. This means that M. steenstrupii could completely dominate the soil crusts throughout the study region.

Exactly how this will affect the deserts is uncertain, but it's likely that it will indeed have an impact. These microbes are hundreds of millions of years old, so a change in soil composition could drive some of them toward extinction. This, in turn, could impact the health of the soil and could even affect farmers.

"This study is relevant beyond desert ecology," said Ferran Garcia-Pichel, microbiologist and professor with ASU's School of Life Sciences, in a news release. "It exemplifies that microbial distributions and the partitioning of their habitats can be affected by global change, something we've long known for plants and animals. This study tells us clearly that we can no longer neglect microbes in our constellations.

The findings are published in the journal Science.

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