The Role of Mycorrhizal Fungi in Carbon Sequestration
Carbon is the main subject of the vast majority of discussions around climate change, as it is a large contributor to the warming of the planet. When addressing climate change, we consistently look to ways to sequester carbon, and often so in ways that rely on natural systems or species that play a significant role in ecology. Plants are an obvious choice for sequestering carbon because they take in carbon during photosynthesis and release carbon into the soil when they decay, but how often do we think about the associated species that make this possible?
Soil ecology essentially serves as the foundation of the communities that grow on the surface, and a key species in this is mycorrhizal fungi, which form symbiotic relationships with a majority of plant species. Boreal forests are a good subject for gaining a better understanding of these interactions because they sequester large net amounts of carbon in the soil by accumulating large amounts of soil organic matter.
Symbiosis between plant roots and mycorrhizal fungi. From BiologyDictionary.net
When considering both regular carbon fixation and additions of carbon through the breakdown of organic matter, it is important to evaluate the extent of the role of mycorrhizal fungi in each to have a more complete understanding of its overall significance. One study, conducted by Clemmensen et al. (2013), examined the chronosequences, or similar ecological sites that differ in age, of forested islands in Sweden to compare the contributions of these two processes to soil carbon content using carbon fixation models. Two categories of island were compared: one had larger islands with more frequent fires, and the other consisted of smaller and infrequently burned islands. By conducting this study, they were able to analyze and compare the contributions of plant litter and fungi processes to soil carbon.
From Clemmensen et al (2013). A) Fungal functional groups associated with soil depths on large, frequently burnt islands (panel 1) and small, infrequently burnt islands (panel 2).
The study found that carbon content was higher in small islands that burned less often, and this was attributed to root-fungi inputs. In the larger islands, it was found that the fungi were absent at the depths where the inputs normally occur. It is explained that this difference was impacted by the greater age and low turnover of the mycelium and in the infrequently burned islands. This finding demonstrates a strong correlation between the presence of mycorrhizal fungi and soil carbon content.
It is ultimately shown that organic matter accumulation on the surface alone does not drive soil carbon content, as many believe. Mycorrhizal fungi carry out the carbon sequestration from plant roots in addition to contributing their own organic matter to the soil. Given this information, those looking to manage carbon storage through soil must take into consideration the state of the fungi communities below the surface in order to truly make a difference in global carbon systems.
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It's so interesting how such large and important processes are controlled by the smallest organisms that we usually wouldn't consider!
ReplyDeleteVery interesting topic and very important too. I like the first paragraph a lot and got me really hooked! I think the paragraphs that describe the methods were a bit less clear, but I liked the way you wrapped it up in the end.
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