Understanding how soil and plants cope with climate change

Managing carbon in the soil is complex, and chemical reactions are essential to trigger responses to help plants grow and develop. Understanding how soil and plants cope with climate change logically leads to questioning the necessary terrestrial ecosystem carbon balance that will be sustainable under future climate-change scenarios.

CO2Land org has previously discussed ‘soil bugs’ under ‘Bugs to cure our climate ills’, on 21 Aug 2012 and more recently further information as been sent on findings that have been on public release (30 Aug 2012 ): “Unexpected finding shows climate change complexities in soil.  While it is hard to describe the finding as surprising it is more evidence of underground organisms ability to play complex roles with greenhouse sequesting.

Presented by mick_kulikowski@ncsu.edu of North Carolina State University  in a paper published in the Aug. 31 edition of Science, “North Carolina State University researchers show that important and common soil microscopic organisms, arbuscular mycorrhizal fungi (AMF), play a role in sequestering carbon below ground, trapping it from escaping into the atmosphere as a greenhouse gas…. Yet at the same time, the study shows, elevated levels of atmospheric carbon dioxide also increase a number of underground decomposing interactions that cause carbon to be released back into the atmosphere as a greenhouse gas. This greenhouse gas release essentially offsets any carbon sink benefits, the researchers found…AMF have a win-win relationship with plants. The fungi take carbon from plants and provide nitrogen and other useful soil nutrients that plants need in order to grow and develop. Present in the roots of about 80 percent of plants that grow on land, AMF help hold this carbon in the ground by putting the brakes on the decomposition of soil organic matter, which prevents the carbon in the decomposing material from escaping into the atmosphere as a greenhouse gas”.

What was so complex in that action you might ask?  The paper says different experiments yielded different results. However all concluded AMF spur other soil micro-organisms to help fill the plant’s need for ammonia. To do so, soil micro-organisms decompose soil organic matter, which allows the carbon to escape into the atmosphere.

Quoting the paper: “We showed that the fungi previously thought to control carbon in the soil can increase carbon decomposition when atmospheric carbon dioxide levels are elevated. ” The study lead Dr. Shuijin Hu, associate professor of plant pathology at NC State and the corresponding author of the paper to say: “But if we effectively manage x, we have a chance to manage carbon sequestration in the soil.”

What CO2Land org reads of this is that regardless, we humans can manage the need for change and anthropogenic change can affect the extent to which terrestrial ecosystems will interact and need the sequester carbon to mitigate climate change is a matter of debate. And to quote the study again “The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric carbon dioxide (CO2) has been assumed to be a major mechanism facilitating soil carbon sequestration by increasing carbon inputs to soil and by protecting organic carbon from decomposition via aggregation. We present evidence from four independent microcosm and field experiments demonstrating that CO2 enhancement of AMF results in significant soil carbon losses. Our findings challenge the assumption that AMF protect against degradation of organic carbon in soil and raise questions about the current prediction of terrestrial ecosystem carbon balance under future climate-change scenarios”.



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