Emission of Gaseous Nitrogen Oxides in Soils of Boreal Forests (Review)

Denitrification losses of nitrogen-containing gases in the biome of boreal forests are discussed. In the soils of coniferous and deciduous forests of Western Europe, 0.57 +/- 0.2 and 1.0 +/- 0.2 kg N-N2O/ha/year are lost during denitrification. In North America this figure was 0.35 +/- 0.29 kg N-N2O/ha/yr for all stands. The emission of N2O from forest soils correlated with the input of nitrogen from the atmosphere with r = 0.47 in coniferous forests and with r = 0.68 in deciduous plantations, returning to the atmosphere up to 30% of the nitrogen supplied with atmospheric precipitation. With a high input of nitrogen from the atmosphere, the emission of nitrogen-containing gases reached 20 kg N/ha/yr. Of these, NO, N2O, and N-2 accounted for 21, 15, and 64%. Measurements of NO and especially N-2 emissions remain very rare, leading to incomplete estimates of denitrification losses. Denitrification remains the most complex process in the nitrogen cycle, with no definitive methods for measuring it.