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Contributed Talk

Session: : Forests: Tropical 2

COS 61-4 - Soil and Stem Carbon Dioxide and Methane Fluxes of an Amazonian Palm Peatland

Tuesday, August 8, 2023
8:45 AM – 9:00 AM PDT
Location: D140
Abstract: South America is the largest area of tropical peatlands representing 46% of the total global tropical peatland area. Tropical peatlands are one of the largest natural sources of atmospheric methane (CH4) and are keystone ecosystems that play a significant role in regional and global carbon budgets. However, little is known about carbon budgets, particularly about soil and tree contribution to ecosystem scale carbon dioxide (CO2) and CH4 fluxes. Here we aim to partition net ecosystem carbon fluxes and to quantify soil and stem carbon fluxes in a tropical palm swamp peatland located near the city of Iquitos, Peru. We established an automatic chamber-based system to measure CO2 and CH4 fluxes from soil and tree stems. We established six collars on the soil covering the spatial variability of the measurement plot and installed stem chambers at 50 cm from the soil surface on the three dominant species on the site: Mauritia flexuosa, Mauritiella armata and Tabebuia insignis. In addition, we installed two chambers at 90cm from the soil surface on two of the studied M. flexuosa to evaluate vertical stem flux variability. The data that we have covers two wet seasons (Jun-Sep 2022 and Nov 2022-Feb 2023) and one dry season (Sep-Oct 2022). We observed a drastic increase in soil CO2 fluxes during the dry season (p-value < 0.05. Fluxes 1.58±0.02 g m-2 h-1 and 0.23±0.002 g m-2 h-1 dry and wet season respectively) and a decrease in soil CH4 fluxes (p-value < 0.05. Fluxes 62.82±0.64 mg m-2 d-1 and 93.43±0.62 dry and wet season respectively). Average stem CO2 fluxes increased during the dry season in all studied species (p-value < 0.05). However, average stem CH4 fluxes, did not show differences between the dry and wet seasons. Our preliminary results points towards no significant diel patterns or spatial heterogeneity on soil carbon fluxes. However, CO2 fluxes might show a diel pattern on stems. These novel results highlight the contribution of stem fluxes to the global C budget and the need for more studies on soil and stem fluxes on tropical palm swamp peatlands.