N2O and CH4 fluxes in undisturbed and burned holm oak, scots pine and pyrenean oak forests in central Spain

Abstract

We investigated N 2 0 and CH 4 fluxes from soils of Quercus ilex, Quercus pyrenaica and Pinus sylvestris stands located in the surrounding área of Madrid (Spain). The fluxes were measured for 18 months from both mature stands and post fire stands using the static chamber technique. Simultaneously with gas fluxes, soil temperature, soil water content, soil C and soil N were measured in the stands. Nitrous oxide fluxes ranged from -11.43 to 8.34 ug N 2 0-N m~2 h" 1 in Q.üex, -1.1 A to 13.52 ug N 2 0-N m -2 h _1 in Q. pyrenaica and -28.17 to 21.89 ug N 2 0-N m~2 h" 1 in P. sylvestris. Fluxes of CH 4 ranged from -8.12 to 4.11 ug CH 4 -C m~2 h" 1 in Q.üex, -7.74 to 3.0 ug CH 4 -C m 2 h l in Q. pyrenaica and -24.46 to 6.07 ug CHzL-Cm^h-1 in P. sylvestris. Seasonal differences were detected; N 2 0 fluxes being higher in wet months whereas N 2 0 fluxes declined in dry months. Net consumption of N 2 0 was related to low N availability, high soil C contents, high soil temperatures and low moisture content. Fire decreased N 2 0 fluxes in spring. N 2 0 emissions were closely correlated with previous day's rainfall and soil moisture. Our ecosystems generally were a sink for methane in the dry season and a source of CH 4 during wet months. The available water in the soil influenced the observed seasonal trend. The burned sites showed higher CH 4 oxidation rates in Q. ilex, and lower rates in P. sylvestris. Overall, the data suggest that fire alters both N 2 0 and CH 4 fluxes. However, the magnitude of such variation depends on the site, soil characteristics and seasonal climatic conditions.

Soil greenhouse gas fluxes from different tree species on Taihang Mountain, North China

“…They considered aerobic denitrification by heterotrophic nitrifiers as a possible pathway, denitrifying bacteria might use atmospheric N 2 O as an alternative electron acceptor to nitrate when the latter was in short supply. Moreover, Inclán et al (2012) demonstrated that N 2 O sink was possibly attributed to high total dissolved organic carbon content and high SM, combined with low levels of SM and nitrogen. However, N 2 O sinks have often been overlooked and the driving factors for these sinks are poorly understood (Goldberg and Gebauer, 2009;Stewart et al, 2012).…”

“…Soil water status thus appear to be important driving factors for N 2 O capture (Goldberg and Gebauer, 2009;Peichl et al, 2010;Gundersen et al, 2012). Forest soils serving as sinks for atmospheric N 2 O have been reported across a broad spectrum of studies (Chapuis-Lardy et al, 2007;Kellman and Kavanaugh, 2008;Peichl et al, 2010;Eickenscheidt and Brumme, 2012;Inclán et al, 2012;Ma et al, 2012;Stewart et al, 2012). Rosenkranz et al (2006) pointed out that the negative N 2 O fluxes were mainly due to very low N availability and high soil C content.…”

Seasonal changes of CO2, CH4 and N2O fluxes in different types of alpine grassland in the Qinghai-Tibetan Plateau of China

“…We assumed that the parameters explaining best the variation of N 2 O fluxes were soil temperature and soil water content. N 2 O production in soils is primarily driven by microbial processes, including nitrification and denitrification, which are related to soil temperature (Inclan et al, 2012). High soil water content can not only stimulate soil microbial activities, but also restrict oxygen diffusion and reduce oxygen concentration in soils, resulting in higher denitrification rates under anaerobic conditions .…”

“…The majority of studies have focused on the exchange of the most important greenhouse gas, CO 2 . However, N 2 O and CH 4 are associated with long-wave solar radiation and play important roles in climatic warming (Inclan et al, 2012). For example, CH 4 is approximately 25 times more powerful in warming the atmosphere than CO 2 for the horizon of 100 years (Chen et al, 2013).…”

“…For example, CH 4 is approximately 25 times more powerful in warming the atmosphere than CO 2 for the horizon of 100 years (Chen et al, 2013). Studies have documented that global atmospheric concentrations of N 2 O and CH 4 have increased markedly as a result of human activities since 1750 and have exceeded the peak values in the pre-industrial period (Inclan et al, 2012). Therefore, information on the CH 4 and N 2 O budgets of terrestrial ecosystems can improve our understanding of both their annual budget and their potential effects for climatic variation (Kato et al, 2011).…”