Papers

Summary

While most soils in periglacial environments present highfluxes of CO2(FCO2), CH4(FCH4), and N2O(FN2O), few ofthem have a tendency to drain greenhouse gases from the atmosphere. This study aimed to assess greenhousegasfluxes at different sub-Antarctic sites and time periods (at the beginning of thaw and height of summer).To investigate the time of year effect on greenhouse gas emissions, FCO2,FCH4,andFN2Owere measured at twosites tundra-covered (Ti and Th) and Nothofagus forest soil (Nf) on Monte Martial, at the southernmost tip ofSouth America, Tierra del Fuego, Argentina. FCO2ranged from 96.33 to 225.72μgCO2m−2s−1across all sitesand periods, showing a positive correlation with soil temperature (Ts) (4.1 and 8.2 °C, respectively) (r2N0.7;pb0.05). The highest values of FCO2were found at Ti and Th (728.2 and 662.64μgCO2m−2s−1, respectively),which were related to higher temperatures (8.2 and 8.6 °C, respectively) when compared to those of Nf. ForFCH4, the capture (drain) occurred during both periods at Nf (−26 and−79μgC–CH4m−2h−1) as well as Tiand Th (−21 and 12μgC–CH4m−2h−1,respectively).FN2Oalso presented low values during both periods andshowed a tendency to drain N2O from the atmosphere, especially at Nf (−2μgN–N2Om−2h−1). In addition,FN2Owas slightly positive for Ti and Th (0.3 and 0.55μgN–N2Om−2h−1, respectively). Soil moisture did notshow a correlation (pN0.05) with the measured greenhouse gasfluxes. A scenario of increased temperatures might result in changes in the balance between the emissions and drains of these gases from soils, leading tohigher emission values of CH4and N2O, especially for tundra covered soils (Ti and Th), where the highest averagefluxes and thermohydric variations were observed over the year.