Exchange of trace gases between soils and the atmosphere in Scots pine forest ecosystems of the northeastern German lowlands 1. Fluxes of N2O, NO/NO2 and CH4 at forest sites with different N-deposition

摘要

This study summarizes the results obtained from measurements of the exchange rates of N2O-N, NO-N, NO2-N and CH4 between Scots pine forest soils of the northeastern German lowlands and the atmosphere in the years 1995-1998. In order to further identify the effects of atmospheric N-deposition on the magnitude of N- and C-trace gas fluxes, five Scots pine forest sites with different loads of atmospheric N-input (15-22 kg N ha(-1) per year) were investigated. The measurements show an increase in NO and N2O fluxes at the higher N-affected sites (mean values, NO: 21-39 mug NO-N m(-2) h(-1), N2O: 16-32 mug N2O-N m(-2) h(-1)) as compared to the sites with moderate atmospheric N-input (mean values, NO: 3-9 mug NO-N m(-2) h(-1), N2O: 5-10 mug N2O-N m(-2) h(-1)). In addition, it could be demonstrated that atmospheric N-deposition did not only effect N-trace gas fluxes at our study sites, but also the magnitude of atmospheric CH4-uptake by the forest soils, since at the pine forest sites with moderate atmospheric N-deposition CH4-uptake rates were approximately two- to five-fold higher (mean values: -140 to -165 mug CH4 m(-2) h(-1)) than at the sites with high atmospheric N-input (-24 to -77 mug CH4 m(-2) h(-1)).