|Brumme, R; Borken, W: N2O emission from temperate beech forests soils in Brumme, R. and Khanna, P.: Ecological Studies, Functioning and Management of European Beech Ecosystems, Springer, 208, 353-367 (2009)|
The interest on N2O emission has increased since the late 1980s after realizing that N2O is an important greenhouse gas (Lashof and Ahuja 1990; Bouwman 1990a) which destroys ozone in the stratosphere by catalytic reactions (Crutzen 1970). The high global warming potential (GWP) of N2O has increased the scientific research effort on assessing N2O fluxes from soils of terrestrial ecosystems (Andreae and Schimel 1989; Bouwman 1990a; Granli and Bøckman 1994) because soils are the largest natural source of N2O (IPCC 2001). Studies in the 1980s suggested that tropical forests are larger sources for N2O than temperate and boreal forests, whereas recent studies have indicated that beech (Fagus Sylvatica L.) forests can have N2O fluxes similar to those observed in tropical forests (Brumme and Beese 1992; Papen and Butterbach-Bahl 1999; Zechmeister-Boltenstern et al. 2002). Beech forests with high annual N2O fluxes have a seasonal emission pattern with high N2O fluxes in summer and low N2O fluxes in winter. However, most temperate forests (beech, spruce, oak) have low background N2O emissions during the year which lack any seasonal trend (Brumme et al. 1999). There are some questions which need to be answered to understand the importance of forests with a seasonal emission pattern for the global balance of N2O (Brumme et al. 2005). In this chapter, temporal and spatial variations of N2O emissions from a beech forest ecosystem with a seasonal emission pattern will be provided, leading to a discussion on the mechanisms and processes responsible for seasonal and background patterns of N2O emissions. Attempts will be made to assess the effect of temperature change, forest management practices (harvesting, liming, soil compaction), and nitrogen inputs on N2O emissions.