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Soil nitrous oxide gas (N2O) emissions

Terrestrial and aquatic nitrogen losses across several tropical forest sites in the DRC

Matti Barthel, Laura Summerauer, Johan Six

The Congo Basin Rainforest is the second largest rainforest in the world covering an area of 3.7 million square kilometres. However, due to political instability and infrastructure, this vast forest ecosystem was mainly inaccessible for environmental scientist. Thus, it remains a blank spot concerning its role in global biogeochemistry, despite representing one of the most important terrestrial ecosystems in the world.
Manual chambers placed on the forest floor in Kahuzi-Biéga National Park to measure temporal and spatial dynamics of greenhouse gas emissions. Photo: Matti Barthel
The understanding of the carbon (C) and nitrogen (N) cycles in these forests are of utmost importance as they are associated with the release and uptake of radiatively active trace gases, namely CO2, CH4, and N2O. Therefore, it is crucial to obtain a solid scientific understanding of the underlying biogeochemical mechanisms driving natural greenhouse gas exchange between land and atmosphere as they can offset anthropogenic emissions and thus mitigate climate change. While there is a dense network of long-term observatory sites for greenhouse gas fluxes in industrialized countries, observations on the African continent are very sparse. So far, there are only about fifteen CO2 flux sites running across the African continent (compared to 550+ globally) and only a handful datasets exist which include in situ N2O emissions from African tropical rainforests.
For the above mentioned reasons, the Sustainable Agroecosystems group at ETH Zurich established, in a concerted effort between the University of Ghent (Belgium) and the University of Bukavu (DRC), a greenhouse gas monitoring network in the DRC. Further, for a better understanding of the potential variability in the fluxes, underlying microbial processes of production and consumption of N2O are going to be elaborated, using isotopic techniques combined with new state of the art methods measuring abundance and diversity of key microbial groups involved in N-cycling and N2O production.
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