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

Abstract

Due to the high temporal and spatial variability of N 2O fluxes, estimates of N 2O emission from temperate forest ecosystems are still highly uncertain, particularly at larger scales. Although highest N 2O 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 N 2O 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 N 2O 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)< Gleysols (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 N 2O is emitted from this soil type. Therefore, regional or national N 2O fluxes from temperate forest soils are underestimated if soils characterised by intermediate aeration conditions are disregarded.