In the present work, post-burning soil N 2O fluxes and related microbial processes were investigated in a Mediterranean shrubland subjected to experimental fires. Nine plots were selected, of which three were used as controls, three were burned with low-intensity fire and three with higher intensity fire. N 2O fluxes, soil humidity and temperature were measured starting 2 days before burning and for 1 year after fire. Potential net nitrification, denitrification enzyme activity, mineral N and organic C were measured from soil samples collected periodically after burning. Cumulative data indicate a doubling of N 2O production in burned plots over 1 year. Burned plots showed an increase of frequency of hot spots of N 2O production. A slight detrimental effect of fire on the analysed biological activities was detected only immediately after burning. After 3 months, both potential net nitrification and denitrification enzyme activity had mostly recovered and potential net nitrification further increased over control levels in the following months. Fire seemed to induce a change in the main source of N 2O, which in control plots was represented by heterotrophic activity (50-75%), whereas in burned plots it was mostly of autotrophic origin, most probably due to the significant increase of soil NH 4+ after burning. © IAWF 2011.
Soil N 2O emissions in a Mediterranean shrubland disturbed by experimental fires
CASTALDI, Simona
2011
Abstract
In the present work, post-burning soil N 2O fluxes and related microbial processes were investigated in a Mediterranean shrubland subjected to experimental fires. Nine plots were selected, of which three were used as controls, three were burned with low-intensity fire and three with higher intensity fire. N 2O fluxes, soil humidity and temperature were measured starting 2 days before burning and for 1 year after fire. Potential net nitrification, denitrification enzyme activity, mineral N and organic C were measured from soil samples collected periodically after burning. Cumulative data indicate a doubling of N 2O production in burned plots over 1 year. Burned plots showed an increase of frequency of hot spots of N 2O production. A slight detrimental effect of fire on the analysed biological activities was detected only immediately after burning. After 3 months, both potential net nitrification and denitrification enzyme activity had mostly recovered and potential net nitrification further increased over control levels in the following months. Fire seemed to induce a change in the main source of N 2O, which in control plots was represented by heterotrophic activity (50-75%), whereas in burned plots it was mostly of autotrophic origin, most probably due to the significant increase of soil NH 4+ after burning. © IAWF 2011.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.