B129-02
Intensive greenhouse gas fluxes from Peruvian peatlands under various environmental drivers
Thursday, 17 December 2020: 07:04
Virtual
Jaan Pärn1, Kaido Soosaar1, Thomas Schindler1, Katerina Machacova2, Waldemar Alegria Muñoz3, Lizardo Fachin4, José Luis Jibaja Aspajo5, Robinson I Negron Juarez6, Jhon Rengifo4, Ricardo Zarate Gomez4, Danika Journeth Garay Dinis5, Adriana Gabriela Arista Overslujs5, Rodil Tello Espinoza3, José David Urquiza Muñoz3, Tedi Pacheco Gomez3 and Ulo Mander7, (1)University of Tartu, Department of Geography, Tartu, Estonia, (2)Global Change Research Institute CAS, Department of Ecosystem Trace Gas Exchange, Brno, Czech Republic, (3)National University of the Peruvian Amazon - UNAP, Forestry Science Faculty, Iquitos, Peru, (4)Instituto de Investigaciones de la Amazonia Peruana, Iquitos, Peru, (5)National University of the Peruvian Amazon, Forestry Science Faculty, Iquitos, Peru, (6)Lawrence Berkeley Natl Lab, Berkeley, CA, United States, (7)University of Tartu, Institute of Ecology & Earth Sciences, Department of Geography, Tartu, Estonia
Abstract:
Amazonian swamp forests sequester carbon to trees and peat. However, in some cases, respiration may outweigh it. Anaerobic decomposition of peat yields methane. Suboxic processes release nitrous oxide. Both have high global warming potential. The balance between the greenhouse gases is delicate. We measured carbon dioxide, methane and nitrous oxide effluxes from the peat and their potential environmental factors in three current or former palm swamps in Iquitos, Peru from September 2019 to March 2020: a natural one, a young forest on toe-slope and a slash-and-burn cassava field. Additionally in the natural swamp we measured greenhouse gas fluxes on stems.
Peat respiration was positively related to water table depth. Thus, the toe-slope and the cassava field respired the largest amounts of carbon dioxide in positive relationship to water table depth. Carbon dioxide efflux from tree stems equalled a quarter of soil respiration. The swamps emitted large amounts of methane in correlation with carbon dioxide efflux from the stem. Concomitantly the palm-stem methane efflux was reversely correlated with peat methane emission, implying competition between the pathways. The waterlogged swamp peat produced a large amount of nitrous oxide from the highly available ammonium. The lack of oxygen and nitrate implied either anammox or co-denitrification as the pathway in the top soil layer. In deeper soil, the oxygen supplied by aerenchymous palm roots may have driven incomplete nitrification with the produced nitrate immediately used up by plants and microbes. In conclusion, the richness of favourable environmental conditions produced a complex pattern of greenhouse gas emissions in the Peruvian Amazon peatlands.
