Methane fluxes from Amazonian tropical peatlands

Abstract

Tropical peatlands are one of the largest soil carbon (C) storage ecosystems in the world and are critical in regulating tropical biosphere and atmosphere CH4 C flux. The Amazonian peatlands of the Pastaza-Maranon foreland basin in Peru experience extreme variations in seasonal conditions. To improve our understand of future impacts on these peatland ecosystems this study aimed to quantify CH4 fluxes from five peatland sites, covering four vegetation types (forested, mixed palm Swamp, Mauritia flexuosa palm swamp (MFPS) and pole forest) over two dry season and two wet season periods. Temporal and spatial variations in CH4 emissions are reported among peatlands, vegetation types and times of day and night to quantify some of the first CH4 fluxes from lowland Amazonian peatlands. CH4 fluxes varied among season by vegetation type and trophic status. CH4 fluxes declined across ombrotrophic peatlands. CH4 flux patterns exist among MFPS peatland locations. MFPS peatlands host significant CH4 flux hot spots of ebullition. Peat pH, EC, DO, WTD’s and temperatures were critical in predicting CH4 fluxes on temporal and spatial scales. CH4 fluxes showed seasonal diurnal patterns, with peak fluxes varying between mornings and afternoons, days and nights with multiple peaks in dry season years. Temporal and spatial variations in abiotic and biotic factors and their interactions with peatland vegetation types and nutrient statuses drive CH4 flux variability in Amazonian peatlands. These CH4 fluxes from multiple temporal and spatial perspectives facilitate an initial basic understanding of Amazonian peatland C cycling and its role in the atmosphere-biosphere system. Upscaled CH4 flux for the MFPS peatland vegetation type over the PMFB may begin to close some of the disparity between bottom up and top down basin CH4 estimates.