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Title Impact of land use and soil properties in the Kavango-region of Northern Namibia on N2O emissions and denitrifier communities

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Short title Effects of land use and soil properties on denitrification

Author(s) Hannig, M.(1); Gröngröft, A.(2); Conrad, R.(1); Braker, G.(1)

Presenting author Hannig, Michael

Institution(s) (1) Department of Biogeochemistry, Max-Planck-Institute for Terrestrial Microbiology Marburg; (2) Institute of Soil Science, University of Hamburg

Keywords Land use; denitrification; greenhouse gas N2O; microbial communities

Abstract Different forms of land use in the Kavango-region in Northern Namibia., e.g. crop cultivation, grazing, and burning of woodlands affect biodiversity and consequently also soil properties and vice versa. We focused on the effects of land use and soil properties on soil microbial communities that produce the greenhouse gas N2O via denitrification, an alternative anaerobic respiration. N2O is emitted from soils and has a global warming potential (GWP) of about 300 times higher than that of CO2. Denitrification also leads to a loss of nitrogen from the soil thereby limiting the availability of this nutrient to plant growth.
Our main objective was to analyze the interlinkage of structure and functioning of denitrifier communities and to unravel factors driving their development and activity at these sites. Potential N2O production was measured as a parameter for denitrification activity. On the acres, very low potential N2O production correlated with a generally low level of denitrifier diversity in contrast to the pristine sites that showed higher diversity and activity. However, differences in the community composition and activity do not correspond to a particular form of cultivation but to other as yet unknown environmental factors. In summary, we found a strong impact of the cropping on denitrifier community structure and functioning resulting in reduced diversity and denitrification potential relative to the pristine sites.

Congress Topic Microbiology

Topic No. 7.4
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Ref. No. 515