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Carbon Flux and its isotopic signature in Arctic regions under climate change (CarIsoA)
IADC_id: 13
active
Call year: 2015
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Permafrost degradation with consequent increase of soil active layer, due to global warming, affects carbon (C) fluxes in Arctic regions, such as Svalbard Islands. Indeed, a huge amounts of organic carbon stored in permafrost soils can be released via soil respiration. On the other hand, climate changes and, in particular, increasing temperature and CO2 concentration may have positive feedback on photosynthetic activity. The balance between photosynthesis and respiration will determine if Arctic regions will act as sink or as source for atmospheric CO2.rnIn this perspective, study the CO2 flux at target species level will be performed along a transect characterized by different levels of permafrost degradation and glacier retreat. In our opinion, not only the balance, but also the distinction in the several components of C flux is of great importance. Our approach to distinguish the several components of the C flux is using carbon stable isotopes. This is possible because of the different signatures of carbon isotope composition in plant material and in soil. These signatures are the results of different biophysical and biochemical fractionation processes occurring to carbon compounds in plant and in soil. The 13C isotope composition will be analyzed both on plant material and soil samples to have an overview of the isotope signature along the continuum plant-soil in different permafrost degradation conditions due to climate change.rnMoreover, it has been shown that volatile organic compounds (VOCs) are associated with protection mechanisms against oxidative stresses, whereas quantitative determination is important to estimate the percentage of C lost by the system in terms of VOCs. Along with CO2 measurements, analysis of VOCs will be done.rnWe will monitor water isotope variations in ecosystem components, too; for this purpose, we will analyze 18O and Deuterium isotope composition on water samples from plant material and soil sample to evaluate ability of plants to take up different kind of water. This will allow determining the contribution during the season of the different kind of water.rnDuring summer 2013 the photosynthetic characterization of 4 plant species (Salix polaris, Saxifraga oppositifolia, Dryas octopetala, Carex rupestris) it has been done, showing differences among the species in the utilization of the light. No differences have been found among the species concerning the CO2 dependence of assimilation rate. Moreover, variations in 13C isotope composition have been found showing different photosynthetic performances, among the species, integrated over the vegetative season.On the base of these preliminary results, a monitoring of carbon flux and 13C isotope composition at plant level is planned for the following years. Together with this, a coupled study of above- and below-ground carbon fluxes is planned to disentangle carbon flux components at ecosystem level.
National/International Cooperation:
Nicoletta Cannone, the Department of Science and High Technology , Università degli Studi dell'Insubria , Varese, Lombardia, Italy
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