Are nitrous oxide emissions and nitrogen fixation linked in temperate bogs?

作者：Rousk Kathrin^*; Vestergard Mette; Christensen Soren

来源：Soil Biology and Biochemistry, 2018, 123: 74-79.

DOI：10.1016/j.soilbio.2018.05.002

• Acetylene reduction
• Diazotrophs
• Nitrogen fixation
• Nitrous oxide
• Pleurozium schreberi
• Sphagnum

A pre-requisite for denitrification and nitrification is the availability of inorganic nitrogen (N). In many natural ecosystems, atmospheric N deposition as well as moss-associated N-2 fixation are the main sources of 'new' N to the ecosystem N pool and could provide inorganic N to sustain N2O production. While a link between N-2 fixation and N2O emissions is plausible, hardly any attempts have been undertaken to test this link in areas with a moss dominated understory. Here, we report results from a combined field and laboratory study in which we assessed N-2 fixation, net N2O emission under different conditions, and potential nitrification and denitrification in three moss species from a Sphagnum-moss dominated, temperate bog. The three moss species were chosen to represent a gradient of N-2 fixation activity. Sphagnum mosses emitted less N2O than the other two moss species (Pleurozium schreberi, Hypnwn cupressiforme), but at the same time, showed the highest N-2 fixation activity. The lack of a link between N-2 fixation and net N2O emissions in three abundant and common moss species indicates that N transformation processes may be decoupled within the moss carpet. This raises new questions on N supply for N2O production and the fate of fixed N-2 in moss-dominated systems.

• 出版日期2018-8