Tuesday, March 29, 2016

Is Climate Change Putting World's Microbiomes at Risk?

Researchers are only beginning to understand the complexities of the microbes in the earth’s soil and the role they play in fostering healthy ecosystems. Now, climate change is threatening to disrupt these microbes and the key functions they provide.

A magnified view of a microbe on Arabidopsis plant roots provides a “window” into the rhizosphere, or root zone. The photo was taken as part of a study by scientists at the U.S. Department of Energy and the Pacific Northwest National Laboratory to examine carbon presence and distribution within the root zone and the impacts on microbial communities' diversity and functions. (Photo Credit: Pacific Northwest National Laboratory) Click to Enlarge.In 1994, scientists at the Pacific Northwest National Laboratory moved soil from moist, high-altitude sites to warmer and drier places lower in altitude, and vice versa. In 2011 they returned to the sites and looked again at the soil microbes and found that they had done little to adapt functionally to their new home.  That's a bad sign, experts say, for a world convulsed by a changing climate. 

"These microbes have somehow lost the capacity to adapt to the new conditions," said Vanessa Bailey, one of the authors of the study, published this month in PLOS One. That not what scientists anticipated, and it "calls into question the resilience of the overall environment to climate change," she said.  "Soil is the major buffer for environmental changes, and the microbial community is the basis for that resilience." 

As snow and ice melt, it's fairly straightforward to grasp what climate change means for the future of, say, polar bears in the Arctic or penguins in Antarctica. But it's far more difficult to understand what is happening to the planetary microbiome in the earth's crust and water, a quadrillion quadrillion microorganisms, according to Scientific American. Yet it is far more important, for microbes run the world. They are key players that perpetuate life on the planet, provide numerous ecosystem services, and serve as a major bulwark against environmental changes. Researchers say that as the planet warms, essential diversity and function in the microbial world could be lost. But they can also cause serious problems — as the world's permafrost melts, microbes are turning once-frozen vegetation into greenhouse gases at a clip that is alarming scientists. 

As vital as they are, we are only beginning to understand microbes and the role they play in the world's ecosystems. The problem is that these fungi, archaea, and bacteria are so small that in a gram of soil (about a teaspoon), there are a billion or so, with many thousands of species. Perhaps 10 percent of the species are known. The Lilliputian communities that these microorganisms create are enormously complex, and their functions difficult to tease out. But in the last decade, new tools have been developed that have begun to change the research game. 
There is a Manhattan Project-like urgency to sussing out these secrets. A paper in the journal Science last year called for a Unified Microbiome Initiative, and experts have held a series of meetings about it at the White House. The Earth Microbiome Project is a massive global effort to collect samples of microbial communities from thousands of ecosystems around the world. Meanwhile, the Global Soil Biodiversity Initiative got underway in 2011 — one-third of the world's biodiversity lives beneath our feet — and it’s focused on preserving the services that healthy soil ecosystems provide, such as a place for plants to grow, the breakdown of waste, and the natural filtration of water. The TerraGenome Project is sequencing the metagenome of soil microbes. 
Interest in microbiomes in the natural world is also exploding because many researchers realize that as the planet warms, essential diversity and function in the microbial world could be lost. Some areas may not be able to grow the same crops they are growing now — in the United States, for instance, no corn in Iowa or wheat in Kansas, because the microbes that currently fix nitrogen for the plants’ roots in the soil will no longer be able to do so. And, as we learn more about how microbes function, there may be ways to put them to work in the service of adaptation — enhancing plant growth, for example, in a warming climate. 

Most urgent, though, is the fact that the earth has locked up a great deal of carbon and should it come unlocked as C02 it could dramatically speed up climate change. "The big question is whether soil will be a sink or source of greenhouse gases in the future," said Jansson. 

Read more at Is Climate Change Putting World's Microbiomes at Risk?

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