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High Methane Emission From Palm Stems and Nitrous Oxide Emission From the Soil in a Peruvian Amazon Peat Swamp Forest

2022; Frontiers Media; Volume: 5; Linguagem: Inglês

10.3389/ffgc.2022.849186

2624-893X

Kaido Soosaar, Thomas Schindler, Kateřina Macháčová, Jaan Pärn, Lizardo Manuel Fachín-Malaverri, Jhon Rengifo, Waldemar Alegría Muñoz, José Luis Jibaja-Aspajo, Robinson Negrón‐Juárez, Ricardo Zárate Gómez, Danika Journeth Garay-Dinis, Adriana Gabriela Arista-Oversluijs, Rodil Tello-Espinoza, Tedi Pacheco-Gómez, Ülo Mander,

Peatlands and Wetlands Ecology

Tree stems in tropical peat swamp forests are known as considerable methane (CH 4 ) emitters; however, little is known about their carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) exchange. Differences between species, especially the role of palm stems in the exchange of greenhouse gasses, have remained largely unknown. We measured stem CO 2 , CH 4 , and N 2 O fluxes from the different heights of widely spread aguaje palms ( Mauritia flexuosa ) and boarwoods ( Symphonia globulifera ) and the soil beneath the same trees in a Peruvian Amazon palm swamp using a static closed chamber technique from September 2019 to March 2020. The tree stems were the net emitters of CO 2 and CH 4 but occasionally showed low N 2 O uptake. We found the highest stem CH 4 emissions (average ± SE) from palm stems of the height of 80 cm (1,601 ± 165.9 μg C m –2 h –1 ), which are more than 300 times greater compared to the highest fluxes from boarwood stems, at the height of 30 cm (5.12 ± 1.27 μg C m –2 h –1 ). The average soil CH 4 flux was 3,618 ± 465 μg C m –2 h –1 . Whereas N 2 O fluxes from the stems were negligible, the average N 2 O fluxes from soils beneath the same trees were relatively high, ranging from 53.75 ± 24.04 (close to boarwood trees) to 143.4 ± 68.43 (close to palms) μg N m –2 h –1 . While roughly upscaling tree-level fluxes to the stand level of 27,732 km 2 of palm swamp in the Pastaza-Marañon foreland basin, these forests are net annual emitters of CH 4 and N 2 O (897 Gg C y –1 and 24 Gg N y –1 , respectively). These results highlight the necessity to study this kind of ecosystem more intensely.