High CH4 and N2O emissions from soil and stems of disturbed swamp forests in Peruvian Amazon

0544635 - ÚVGZ 2022 DE eng A - Abstract
Pärn, J. - Soosaar, Kaido - Schindler, Thomas - Macháčová, Kateřina - Muñoz, A.W. - Malaverri, F.M.L. - Aspajo, J.L.J. - Juarez-Negron, R. - Marin, R.E.J. - Espinoza, T.R. - Horna, C.S. - Gómez, P.T. - Muñoz, U.D.J. - Mander, Ülo
High CH4 and N2O emissions from soil and stems of disturbed swamp forests in Peruvian Amazon.
EGU General Assembly 2020. on line: European Geosciences Union, 2020.
[EGU General Assembly 2020. 04.05.2020-08.05.2020, online]
Institutional support: RVO:86652079
Keywords : methane * nitrous oxide * tropical peatland * amazon * flux * tree stems * palm * soil * swamp forest * cassava field * plantation * environmental factors
OECD category: Plant sciences, botany
www.egu2020.eu

With an objective to clarify the greenhouse gas budget of tropical peatlands, we held a measurement campaign in Iquitos, Peruvian Amazon in September 2019. We observed fluxes of CH4, N2O and CO2 using opaque chambers and measured potential environmental factors in three sites under various disturbance histories: 1) a Mauritia flexuosa palm-dominated swamp forest, 2) toe-slope swamp forest grown in 12 years on fallow pasture and banana plantation, and 3) slash-and-burn cassava field. The toe-slope swamp respired the largest amounts of CO2 while site differences were small and may have been offset by photosynthesis (which we did not measure). The wet swamp forest sites, especially palm trunks, emitted large amounts of CH4. The dry slash-and-burn cassava field emitted little CH4 The CH4 emissions were strongly correlated with nitrogen (N) content of the peat. Previous literature links high soil N content with lability of soil organic carbon and high microbial activity. The swamp forest floor emitted an average of 390 μg N2O-N m–2 h–1 after torrential rainfall. The downpour may have carried just enough O2 into the peat to trigger N2O production by nitrification or hamper the full pathway of denitrification to N2. High peat Ca++ and Mg++ content and pH>4 favoured nitrification. High NH4 +-N concentration in the swamp peat (190 mg kg–1), which can be related to N2 fixation and litter from three species of leguminous trees, formed a solid base for nitrification. The slash-and-burn cassava field emitted a sizable 37 μg N2O-N m–2 h–1. In conclusion, the variety of disturbances produced an interesting pattern of greenhouse gas emissions in relationship with environmental conditions.
Permanent Link: http://hdl.handle.net/11104/0321468