The CO2 detective
Top image: Stefano Ponti checks the machine that measures CO2 fluxes in the ground in Adventdalen. Photo: Eva Therese Jenssen/UNIS.
Are the plants and soil in Adventdalen absorbing more CO2 than they are emitting into the atmosphere? Stefano Ponti (23) from Italy investigates the matter every day this summer.
5 August 2013
Text and photos: Eva Therese Jenssen / UNIS
More carbon is stored in the world’s soils—including peatlands, wetlands and permafrost—than is present in the atmosphere. However, the effects of climate change on global soil carbon stocks are still unclear, with potentially positive feedbacks if warming accelerates soil carbon decomposition, and conversely negative feedbacks if plant-derived carbon inputs exceed decomposition.
Carbon sinks or sources?
It is becoming increasingly important to understand whether climate change will turn cold ecosystems from large long-term carbon sinks into carbon sources, a topic that is still hotly debated because of the great potential for ecosystem-mediated feedbacks to the climate.
Stefano is taking a master in environmental sciences at the University of Varese in Italy. The fieldwork is conducted in Adventdalen, close to Mine 6, and will hopefully shed some more light on the sink-or-source issue.
– My master project is to measure of carbon fluxes from the ground in correlation with different kinds of vegetation and different kinds of soils, Stefano explains as he turns on the little machine that is hovering above a cluster of flowers and moss in Adventdalen.
Both plants and soils, including permafrost, are key environmental components determining ecosystem CO2 flux; moreover, their C cycling processes (primary production, decomposition, and respiration) are influenced by climate change through increases in temperature, permafrost thaw, and soil moisture.
– We aim to analyse the spatial variability of soil CO2 emission measured under different active layer (thickness and thermal regime) and vegetation conditions in the Adventdalen area to assess whether active layer conditions, vegetation type and soil conditions may influence the spatial variability of CO2 fluxes, he elaborates.
The machine Stefano is using is measuring how much CO2 the ground is emitting or absorbing. Every day he is out in the valley to do his measurements at the different plots he has chosen. He started up in the beginning of July and will continue his fieldwork until October.
During the summer it seems that the CO2 emission has decreased and CO2 absorption has increased.
– Every plot I measure emitted more CO2 in the beginning of my field period. Now, the soil and plants are absorbing more CO2 because of increased photosynthesis. In other words, the microorganisms in the soil and the plants are “eating” up more CO2 than they are “breathing” out in the atmosphere, Stefano explains.
However, that might change if the Arctic continues to warm up.
– If the ground temperature increases, we expect more respiration of CO2 by the bacteria in the soil, Stefano says.
– I have to figure out who wins this summer; photosynthesis by the plants (absorption) or respiration by the bacteria.