(Poster: Luca B. Marchesini) Net Ecosystem Carbon Balance of a tundra ecosystem in the Siberian Arctic Today, we are happy to present the abstract of Luca Belelli Marchesini, Ko van Huissteden, Artem Budishchev, Angela Gallagher, Yan Jiao Mi, T.C. Maximov, R. Petrov and Han Dolman, partners to PAGE21 Project from the University of Amsterdam.

The Arctic exhibits the largest increase in surface temperature occurred in the last century among all the regions in the world and climate change is expected to further accelerate leading to a projected warming effect of 3-4 °C in the next 50 years, more than twice the global mean (IPCC, 2013).

 

Terrestrial arctic ecosystems are considered a hot spot in the global carbon cycle for the massive (1700 Pg) pool of carbon so far stored in the permafrost (Tarnocai et al., 2009) that may be potentially released to the atmosphere as greenhouse gases, in the form of CO2 and CH4, exerting an intense positive feedback on the climate system.

 

However warmer temperatures stimulate at the same time the increase in primary productivity of Arctic vegetation that is at the base of the observed "greening" of the region in the last three decades (Xu et al. 2013).

 

These two contrasting processes make the forecast of the net land-atmosphere carbon flux over the arctic tundra environments in the next decades very uncertain and call for the direct monitoring of GHG fluxes as a mean to produce updated carbon budgets and evaluate how high latitude ecosystems are being reacting to climate warming.

 

Most of the studies developed in this direction have so far quantified the GHG exchange of tundra ecosystems with the atmosphere but only few included lateral fluxes of carbon (inputs or outputs as non gaseous carbon) in the budget which ultimately yield the rate of carbon gain or loss of a given area (Chapin III et al., 2006). In the region of the Siberian tundra the mobilization of carbon as dissolved and particulate organic matter represents the major unknown term of the carbon balance.

Here we present a recent assessment of the net ecosystem carbon budget of a tundra ecosystem in north eastern Russia (Kytalyk, 70°49'N, 147°29'E), based on continuous micrometeorological measurements of CO2 and CH4 vertical fluxes as well as on the quantification of the lateral export of dissolved organic carbon to the river system.

 

Observations covered the period from May to September in 2012 including the snowmelt phase and the whole growing season. The site was found to act as a carbon sink with a magnitude of about 110 gC m-2 resulting substantially from the uptake of 115 gC m-2 of CO2. The net flux of CH4 to the atmosphere (2.7 gC m-2) decreased by only 12% the GHG sink, considering the global warming potential of methane compared with carbon dioxide. Interestingly, the lateral flux of DOC (3.1 gC m-2) represented a non negligible term (3%) of the NECB.

 

To learn more about the research, watch the video prepared as a part of Frostbyte initiative, by Luca B. Marchesini