January 9, 2014
Are Fungi Secret Soldiers In The Battle Against Climate Change?
Ranjini Raghunath for redOrbit.com - Your Universe Online
Most people know fungi as the yeast that makes their bread or the mold that leaves them wheezing at night. But there are hundreds of these creatures working quietly on the sidelines to make the world a better place: from brewing beer to keeping the soil fertile and now, it turns out, combating climate change.
Symbiotic fungi that live inside plants’ roots can trap more carbon than plants alone can. In places where these fungi partnered up with plants, 70 percent more carbon was absorbed from the air and stored in the soil, the study found. The fungi’s ability to trap carbon does not appear to change with changes in rainfall, temperature or soil content.
As long as plants live, they absorb most of the noxious carbon dioxide that humans pump into the air. When they die, however, their they rot and releases carbon into the soil. Some soil microbes use up this carbon for their energy and release CO2 back into the air, effectively canceling out the plant’s good deed.
Here’s where fungi come to the rescue. Living in the plants’ roots, they help their benefactor by taking in nitrogen from the soil needed for the plants’ growth. Soil microbes also need nitrogen for their growth. This competition for nitrogen, between the plant-and-fungi couple and soil microbes, reduces the microbes’ ability to decompose dead matter, and in turn reduces the amount of CO2 pumped back into the air.
Soil contains more carbon than air and plants combined; a small change in the soil’s carbon content could have large ripple effects on the global carbon cycle. Future CO2 levels in the air could depend heavily on how much carbon is trapped in the soil, the researchers believe.
So far scientists have mostly been looking at plants and the climate, and not other creatures in the soil, as the controlling factors for soil carbon content.
“This analysis clearly establishes that the different types of symbiotic fungi that colonize plant roots exert major control on the global carbon cycle, which has not been fully appreciated or demonstrated until now,” said Colin Averill, lead author and University of Texas, Austin graduate student said.
“Trees and decomposers are really connected via these mycorrhizal fungi, and you can't make accurate predictions about future carbon cycling without thinking about how the two groups interact. We need to think of these systems holistically.”