Hi everybody! Can someone provide me some info regarding soil CO2 dynamics within continental climate areas?
For example in Mediterranean areas soil respiration is influenced by i) soil water content in the dry period and ii) by soil T°C in the rest of the year. What about Continental or sub-alpine climate soils?
CO2 production in soils comes from two sources: decomposition from organic matter (heterotrophic respiration, Rh) and from the respiration of root tissue (autotrophic respiration, Ra). Decomposition rate is driven by the quality of the substrate, the number and type of organisms doing the decomposing, and the conditions (temperature and moisture). Autrophic respiration can also covary with environmental conditions below ground but also is related to above ground activity of the plants. Regardless of where we are (desert to tropics) these factors all have a role. In a situation you describe, low temperatures, perhaps non-liquid soil moisture AND plant dormancy will certainly result in less soil CO2 production. As temperatures warm, as water is readily available in the soil (but not affecting O2 availability), and as roots are active and photosynthates are flowing from roots to fungi to microbes you'll see peak CO2 production. The issue is trying quantifying this:) Good luck, measure many locations and measure frequently, and you'll find some answers... as well as lots of new questions!:)
It is essentially the same in subalpine soils and permafrost areas, though there can be actual sequestering of carbon dioxide after permafrost has thawed, e.g., along the south shores of Hudson Bay. This is due to the greatly increased plant (herbs, shrubs and bryophytes) when the ground is wet and warmer.
Stuart.
In regions with seasonal soil freezing gas emission in some seasons will be controlled by also a process of freezing and thawing. Especially if the soil is wet.
We see seasonal variation in CO2 flux in temperate climates. Mainly associated with soil temperature but also root respiration during the growing season. However, I have measured soil respired d13C-DIC in snowpack in mid winter at high altitudes. Snowpack seems to insulate the soil and maintaining a small flux to the overlying snowpack.
CO2 production in soils comes from two sources: decomposition from organic matter (heterotrophic respiration, Rh) and from the respiration of root tissue (autotrophic respiration, Ra). Decomposition rate is driven by the quality of the substrate, the number and type of organisms doing the decomposing, and the conditions (temperature and moisture). Autrophic respiration can also covary with environmental conditions below ground but also is related to above ground activity of the plants. Regardless of where we are (desert to tropics) these factors all have a role. In a situation you describe, low temperatures, perhaps non-liquid soil moisture AND plant dormancy will certainly result in less soil CO2 production. As temperatures warm, as water is readily available in the soil (but not affecting O2 availability), and as roots are active and photosynthates are flowing from roots to fungi to microbes you'll see peak CO2 production. The issue is trying quantifying this:) Good luck, measure many locations and measure frequently, and you'll find some answers... as well as lots of new questions!:)
Seasonal dynamics of soil respiration may be also affected by "substrate limitation" and "microbial priming". Some references can be found here:
https://www.researchgate.net/publication/263033059_Explaining_the_seasonal_cycle_of_the_globally_averaged_CO2_with_a_carbon_cycle_model
Article Explaining the seasonal cycle of the globally averaged CO2 w...
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