Spatial variations of nitrogen trace gas emissions from tropical mountain forests in Nyungwe, Rwanda

  • Globally, tropical forest soils represent the second largest source of N2O and NO. However, there is still considerable uncertainty on the spatial variability and soil properties controlling N trace gas emission. Therefore, we carried out an incubation experiment with soils from 31 locations in the Nyungwe tropical mountain forest in southwestern Rwanda. All soils were incubated at three different moisture levels (50, 70 and 90 % water filled pore space (WFPS)) at 17 °C. Nitrous oxide emission varied between 4.5 and 400 μg N m−2 h−1, while NO emission varied from 6.6 to 265 μg N m−2 h−1. Mean N2O emission at different moisture levels was 46.5 ± 11.1 (50 %WFPS), 71.7 ± 11.5 (70 %WFPS) and 98.8 ± 16.4 (90 %WFPS) μg N m−2 h−1, while mean NO emission was 69.3 ± 9.3 (50 %WFPS), 47.1 ± 5.8 (70 %WFPS) and 36.1 ± 4.2 (90 %WFPS) μg N m−2 h−1. The latter suggests that climate (i.e. dry vs. wet season) controls N2O and NO emissions. Positive correlations with soil carbon and nitrogen indicate a biological control over N2O and NO production. But interestingly N2O and NO emissions also showed a positive correlation with free iron and a negative correlation with soil pH (only N2O). The latter suggest that chemo-denitrification might, at least for N2O, be an important production pathway. In conclusion improved understanding and process based modeling of N trace gas emission from tropical forests will benefit from spatially explicit trace gas emission estimates linked to basic soil property data and differentiating between biological and chemical pathways for N trace gas formation.

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Author:Nasrin Gharahi Ghehi, Christian Werner, Landry Cizungu Ntaboba, Jean Jacques Mbonigaba Muhinda, Eric Van Ranst, Klaus Butterbach-BahlORCiDGND, Ralf Kiese, Pascal Boeckx
URN:urn:nbn:de:hebis:30:3-243152
DOI:https://doi.org/10.5194/bg-9-1451-2012
ISSN:1726-4189
ISSN:1726-4170
Parent Title (English):Biogeosciences
Publisher:Copernicus
Place of publication:Katlenburg-Lindau [u. a.]
Document Type:Article
Language:English
Date of Publication (online):2012/04/19
Date of first Publication:2012/04/19
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2012/05/23
Volume:9
Issue:4
Page Number:13
First Page:1451
Last Page:1463
Note:
© Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License.
HeBIS-PPN:303695706
Institutes:Geowissenschaften / Geographie / Geowissenschaften
Fachübergreifende Einrichtungen / Biodiversität und Klima Forschungszentrum (BiK-F)
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften
Sammlungen:Universitätspublikationen
Sammlung Biologie / Sondersammelgebiets-Volltexte
Licence (German):License LogoCreative Commons - Namensnennung 3.0