Controls over N2O, NOx and CO2 fluxes in a calcareous mountain forest soil

Kaltenburg-Lindau

Copernicus Publications

2005

S. 1423-1455

Artikel aus einer ZeitschriftUnselbständiges Werk

200127682

Biogeosciences Discussions ; (2), S. 1423-1455

We measured nitrogen oxides (N2O and NOx), dinitrogen (N2) and carbon dioxide (CO2) emissions from a spruce-fir-beech forest soil in the North Tyrolean limestone Alps in Austria. The site received 12.1 kg nitrogen via wet and dry deposition. Fluxes of nitric oxide (NO) were measured by an automatic dynamic chamber system on an hourly basis over a two year period. Daily N2O emissions were obtained by a semi-automatic gas measuring system. In order to cover spatial variability biweekly manual measurements of N2O and CO2 emissions were carried out, additionally. For acquiring information on the effects of soil and meteorological conditions and of N-deposition on N-emissions we chose the autoregression procedure (time-series analysis) as our means of investigation. Hence, we could exclude the data's autocorrelation in the course of the time. We found that soil temperature, soil moisture and wet N-deposition followed by air temperature and precipitation were the most powerful influencing parameters effecting N-emissions. Weith these variables up to 89 % of observed temporal variations of N-emissions could be explained. During the two-year investigation period between 2.5 and 3.5 % of deposited N was reemitted in form of N2O whereas only 0.2 % were emitted as NO. At our mountain forest site the main end-product of microbial activity processes was N2 and trace gases (N2O and NO) were only of minor importance.