Tropical peat accumulation in Central Amazonia

Abstract

Amazonia has been recently included in discussions on the role of tropical peatlands in the global carbon cycle owing to extensive peatlands up to 7.5 m thick, reported from Western Amazonia (Peru). The aim of this study was to explore peat accumulation in Central Amazonia (Brazil). Of seven field sites, six located in the Negro River basin and one close to the junction of the Negro River with the Amazon, four had a peat deposit from 0.10 to 2.10 m thick. Another two sites had other organic soil type which could not be called peat. Only one site did not have any organic deposit. The loss-on-ignition (LOI), carbon content and dry bulk density, measured for the four peatland sites, varied from 17.7 to 97.4 %, 11 to 59 %, and 0.0002 to 0.572 g cm-3, respectively. All sites were classified as minerotrophic based on pH and peat thickness. The study confirms that Amazonian peatlands are not limited to Western Amazonia but also exist in Central Amazonia. We could not find as thick and extensive peats as in Western Amazonia, which we suggest is due to differences in rainfall and hydrology, tectonic conditions, topography, subsoil type and frequency of fires. © 2013 Society of Wetland Scientists.