Soil microbes affect carbon levels

Posted Sep 15, 2014 by Tim Sandle
The life-cycle of soil microbes in warmer temperatures appears to affect soil carbon storage. The slower the rate of growth, the more carbon that is released into the atmosphere. A new study suggests that a change is taking place.
The finding is important because soil dwelling microbes consume organic carbon compounds in soil. Some of the utilized carbon is released into the atmosphere as carbon dioxide. The new study indicates that the rate at which microbes in warmer climates are surviving and reproducing is slowing, and that this could be leading to a rise in carbon dioxide levels in the soil and less released into the atmosphere.
The conventional theory is that due to the increase in temperature of the soil, carbon dioxide levels in our atmosphere increase, the mean average temperature of the Earth is rising. However, the new study suggests that this may not be the case. The reason for this is that higher temperatures leads to the soil microbes growing faster, but they also die faster. The net result could be less carbon emitted.
For the research, scientists incubated soil from a peatland and a forest in Minnesota at different temperatures and measured the efficiency with which soil bacteria grew. To track what was happening, the researchers added small amounts of sugar and studied how individual atoms in this sugar were turned into carbon dioxide. Because bacteria process sugars researchers can predict which carbon atoms in sugar molecules end up as carbon dioxide, and which are used to build new microbes.
Whilst the research points towards warmer temperatures leading to faster growing microbes and thus to less carbon release, further research is required and for this new experimental models will be required.
The study was led by Shannon Hagerty and Paul Dijkstra from Northern Arizona University. The findings have been published in the journal Nature Climate Change. The paper is headed “Accelerated microbial turnover but constant growth efficiency with warming in soil”.
Relationships between soil, forests and climate change are complex. In a related story, Digital Journal has considered the impact of deforestation in the Amazon on microbial communities and carbon levels.