Nitrous oxide emissions from mineral and organic soils of a Norway spruce stand in South-West Germany

Due to the high temporal and spatial variability of N2O fluxes, estimates of N2O emission from temperate forest ecosystems are still highly uncertain, particularly at larger scales. Although highest N2O emissions with up to 7.0 kg N ha(-1) yr(-1) were mainly reported for soils affected by stagnant water, most of the reported gas flux measurements were performed at forest sites with well-aerated soils yielding mostly to low mean annual emission rates less than 1.0 kg N ha(-1) yr(-1). This study compares N2O fluxes from upland (Cambisols) and temporally water-logged (Gleysols, Histosols) soils of the Central Black Forest (South-west Germany) over a period of 2 yr. Mean annual N2O fluxes from investigated soils ranged between 0.2 and 3.9 kg N ha(-1) yr(-1). The fluxes showed a large variability between the different soil types. Emissions could be clearly ranked in the following order: Cambisols (0.26-0.75 kg N ha(-1) yr(-1)) < Gle (1.37-2.68 kg N ha(-1) yr(-1)) < Histosol (3.66-3.95 kg N ha(-1) yr(-1)). Although the Cambisols cover two-thirds of the investigated area, only about half of the overall NO is emitted from this soil type. Therefore, regional or national N2O fluxes from temperate forest soils are underestimated if soils characterised by intermediate aeration conditions are disregarded. (c) 2006 Elsevier Ltd. All rights reserved.