HR: 0800h
AN: B41C-05    [Abstracts]
TI: Immediate Impact of Elevated Nitrogen Input on Trace Gases Emissions in an old-Growth Lowland Forest in Panama
AU: * Wullaert, H
EM: hans.wullaert@gmail.com
AF: Geographical Institute, University of Mainz, Mainz, 55099, Germany
AU: Veldkamp, E
EM: eveldka@gwdg.de
AF: Institute of Soil Science and Forest Nutrition, University of Goettingen, Buesgenweg 2, Goettingen, 37077, Germany
AU: Corre, M D
EM: mcorre@gwdg.de
AF: Institute of Soil Science and Forest Nutrition, University of Goettingen, Buesgenweg 2, Goettingen, 37077, Germany
AB: In tropical areas, nitrogen (N) emission, transport and deposition are projected to increase rapidly in the next decades. In this study, the consequences of elevated N input on trace gases emissions from a tropical lowland forest soil were evaluated. The study site is located in Gigante Peninsula, Panama, which included control and N addition treatments each with four replicate plots. Urea-N was applied twice in 2006 (April 28 and June 6) at a rate of 31.25 kg N ha^-1 each application. Nitrous oxide (N₂O), nitric oxide (NO), carbon dioxide (CO₂) and methane (CH₄) fluxes were intensively measured prior to and until one month after the second N application; this measurement period was within the beginning of the rainy season. We observed significantly higher NO emissions from the N-fertilized than the control plots, but N₂O, CO₂ and CH₄ fluxes did not differ. The increased NO fluxes were largely observed during the first week after the second fertilization, when water-filled pore space (WFPS) has increased as the rainy season progressed. N₂O emissions could possibly increase with N addition when soil moisture further increase into the rainy season. The significant correlation between N₂O + NO fluxes and NH₄⁺ levels and the range of WFPS (40-60%) indicated that N trace gases were possibly predominantly produced by nitrification. The fertilizer- induced N oxide emission was 3% of the applied N. The CO₂ and CH₄ fluxes indicated that initial N addition did not bring detectable change in microbial decomposition and root respiration for CO₂ emissions and in CH₄ consumption and production for CH₄ fluxes, at least during the early rainy season covered in our measurement.
DE: 0419 Biomineralization
DE: 0469 Nitrogen cycling
DE: 0490 Trace gases
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
SC: Biogeosciences [B]
MN: 2007 Joint Assembly