Re: How do soil microbes affect global warming?

Dear Ditro
I am really sorry for  this late answer...
I was away on a meeting.....
Well I think I answered a little on the role of soil microbes in my previous reply....
Let me elaborate more...

Scientists at the University of Toronto Scarborough have published research findings in the 
prestigious journal, Nature Geoscience, that show global warming actually changes the molecular 
structure of organic matter in soil.
"Soil contains more than twice the amount of carbon than does the atmosphere, yet, until now, 
scientists haven't examined this significant carbon pool closely," says Myrna J. Simpson, principal 
investigator and Associate Professor of Environmental Chemistry at UTSC. "Through our research, 
we've sought to determine what soils are made up of at the molecular level and whether this 
composition will change in a warmer world."
Soil organic matter is what makes dirt fertile and able to support plant life – both of which are 
especially important for agriculture. Organic matter retains water in the soil and prevents 
erosion. Natural processes of decomposition of soil organic matter provide plants and microbes 
with the energy source and water they need to grow, and carbon is released into the atmosphere 
as a by-product of this process. Warming temperatures are expected to speed up this process 
which will increase the amount of CO2 that is transferred to the atmosphere.

Experiments have shown that soil bacteria, not plants, were responsible for large-scale methane 
emissions.

Current models of global climate change predict warmer temperatures will increase the rate that 
bacteria and other microbes decompose soil organic matter, a scenario that pumps even more 
heat-trapping carbon into the atmosphere. 

Carbon is held in soil either in material that is easily degraded by chemical and bacterial action 
(labile soil carbon), or in material that is less easily degraded by microorganisms (resistant soil 
carbon). About one third of the world’s soil carbon is located in high latitudes such as the Arctic, 
and much of this effectively locked away in recalcitrant stores.
If this carbon were ever released into the atmosphere as carbon dioxide, the concentration of 
this ‘green-house gas’ would increase considerably, leading to a substantial increase in global 
warming.
The question that researchers in Austria, Russia and Finland asked was whether increasing global 
temperatures that are already predicted could enable micro organisms to use this carbon. Their 
results are published in this week’s edition of Rapid Communications in Mass Spectrometry.
The researchers incubated soil cores at 2oC, 12oC and 24oC. They found that resistant soil 
carbon was preferentially respired by arctic microbes at higher temperatures, presumably due to 
a shift in microbial populations.
They also found that the change in the relative proportion of different microorganisms in the soil 
was not driven by a depletion of more readily available carbon, but simply by the change in 
temperature.
“This temperature driven change in availability of resistant carbon is of crucial importance in the 
context of climate change,” says co-author Andreas Richter who works at the Institute of 
Ecology and Conservation Biology at the University of Vienna, Austria. “It may be that the whole 
idea of ‘resistant carbon compounds’ in arctic soils may only be relevant within a cool world and 
have no place in a future warmer world.”

It is obvious that soil microbes do play a role in Global warming more than plants do...but also 
soil microbes are important in the decomposition of organic matter in the soil...

So I can sat that they play a dual role, but it is still not completely clear about the impact they 
will have on the current and future prediction of their role in global warming.

Below are some reference that you might be interested.....

Regards
Shashank

 http://www.physorg.com/news146746338.html http://www.scientificblogging.com/news_releases/impact_soil_microbes_global_warming_less_p
reviously_predicted http://www.physorg.com/news4009.html http://www.eurekalert.org/pub_releases/2008-10/uog-shc102808.php