Nitrogen oxides emission from two beech forests subjected to different nitrogen loads

Kaltenburg-Lindau

2005

Sonderdruck

12675S

40000973

We measured nitrogen oxides (N2O and NOx) and carbon dioxide (CO2) emissions from two beech forest soils near Vienna, Austria, which were exposed to different loads of nitrogen input from the atmosphere. The site Schottenwald (SW) was receiving 27 kg and Klausenleopoldsdorf (KL) 15 kg nitrogen via wet and dry deposition. N2O and CO2 emissions were measured with manually operated chambers biweekly (SW) or monthly (KL). Additionally, daily N2O measurements were carried out with an automatic gas sampling system. NOx emissions from soil were detected hourly with an automatic dynamic chamber system. We used the autoregression procedure (time-series analysis) to estimate the relationship between nitrogen oxide emissions and several climate, soil chemistry and N-deposition data. Changes in soil moisture and soil temperature had the most profound effect on CO2 and on nitrogen oxide emissions and could explain up to 94% of the temporal variations of gas emissions. In the two investigation years, annual gaseous N losses ranged from 0.70 to 0.82 kg N2O-N ha−1 y−1 and from 0.34 to 0.61 kg NO-N ha−1 y−1 in SW. In KL significantly lower annual N2O emissions were determined (0.43 and 0.66 kg N2O-N kg ha−1 y−1). In KL measuring campaign, revealed a NO-loss of 0.02 kg, whereas in the same time significantly more NO was emitted in SW (0.32 kg NO-N ha−1 y−1). Higher nitrogen oxides, especially NO emissions from the high nitrogen input site (SW) indicate that atmospheric deposition had a strong impact on losses of gaseous nitrogen from