Soil-atmosphere greenhouse gases (CO2, CH4 and N2O) exchange in evergreen oak woodland in southern Portugal
A. Shvaleva, R. Lobo-do-Vale, C. Cruz, S. Castaldi, A.P. Rosa, M.M. Chaves, J.S. Pereirahttps://doi.org/10.17221/223/2011-PSECitation:Shvaleva A., Lobo-do-Vale R., Cruz C., Castaldi S., Rosa A.P., Chaves M.M., Pereira J.S. (2011): Soil-atmosphere greenhouse gases (CO2, CH4 and N2O) exchange in evergreen oak woodland in southern Portugal. Plant Soil Environ., 57: 471-477.
A 10–20% decrease in annual precipitation is predicted in the Mediterranean basin, and in particular to the Iberian Peninsula, with foreseen effects on the exchange of soil-atmosphere greenhouse gases (GHGs; CO2, CH4, and N2O). To simulate this scenario, we setup an experimental design in the particularly dry period of 2008–2009 using rainfall exclusion and irrigation, to obtain plots receiving 110% (538 mm), 100% (493 mm) and 74% (365 mm) of the natural precipitation. Soil CO2 fluxes showed a strong increase from summer to autumn as a consequence of increasing soil heterotrophic respiration that resulted from rewetting. Fluxes of N2O were negligible. According to our data, soil was a permanent CH4 sink independent of the soil water content (in the range between 6–26% WFPS – water-filled pore space) and of soil temperature (in the range of 7–28°C), supporting the concept that seasonally dry ecosystems (Mediterranean) may represent a significant sink of atmospheric CH4. The study provides evidence that the 26% decrease or 10% increase in the ambient rainfall from annual precipitation of ca 500 mm did not significantly affect soil functionality and had a limited impact on soil-atmosphere net GHGs exchange in evergreen oak woodlands in southern Portugal.Keywords:
climate change; drought; Mediterranean; precipitation