Erratum: Large emissions from floodplain trees close the Amazon methane budget.

This corrects the article DOI: 10.1038/nature24639.

Large emissions from floodplain trees close the Amazon methane budget.

Wetlands are the largest global source of atmospheric methane (CH), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH in the tropics, consistently underestimate the atmospheric burden of CH determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH emissions. Here we report CH fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin.

The contribution of trees to ecosystem methane emissions in a temperate forested wetland.

Wetland-adapted trees are known to transport soil-produced methane (CH ), an important greenhouse gas to the atmosphere, yet seasonal variations and controls on the magnitude of tree-mediated CH emissions remain unknown for mature forests. We examined the spatial and temporal variability in stem CH emissions in situ and their controls in two wetland-adapted tree species (Alnus glutinosa and Betula pubescens) located in a temperate forested wetland. Soil and herbaceous plant-mediated CH emissions from hollows and hummocks also were measured, thus enabling an estimate of contributions from each pathway to total ecosystem flux.

Controls on methane emissions from Alnus glutinosa saplings.

Recent studies have confirmed significant tree-mediated methane emissions in wetlands; however, conditions and processes controlling such emissions are unclear. Here we identify factors that control the emission of methane from Alnus glutinosa. Methane fluxes from the soil surface, tree stem surfaces, leaf surfaces and whole mesocosms, pore water methane concentrations and physiological factors (assimilation rate, stomatal conductance and transpiration) were measured from 4-yr old A.

Trees are major conduits for methane egress from tropical forested wetlands.

Wetlands are the largest source of methane to the atmosphere, with tropical wetlands comprising the most significant global wetland source component. The stems of some wetland-adapted tree species are known to facilitate egress of methane from anoxic soil, but current ground-based flux chamber methods for determining methane inventories in forested wetlands neglect this emission pathway, and consequently, the contribution of tree-mediated emissions to total ecosystem methane flux remains unknown. In this study, we quantify in situ methane emissions from tree stems, peatland surfaces (ponded hollows and hummocks) and root-aerating pneumatophores in a tropical forested peatland in Southeast Asia.

Archaeol: an indicator of methanogenesis in water-saturated soils.

Oxic soils typically are a sink for methane due to the presence of high-affinity methanotrophic Bacteria capable of oxidising methane. However, soils experiencing water saturation are able to host significant methanogenic archaeal communities, potentially affecting the capacity of the soil to act as a methane sink. In order to provide insight into methanogenic populations in such soils, the distribution of archaeol in free and conjugated forms was investigated as an indicator of fossilised and living methanogenic biomass using gas chromatography-mass spectrometry with selected ion monitoring.

Investigation of the methanogen population structure and activity in a brackish lake sediment.

The methanogen community in sediment from the edge of a small brackish lake connected to the Beaulieu Estuary (Hampshire, UK) was investigated by analysis of 16S rRNA gene diversity using new methanogen-specific primers plus Archaea-specific primers. 16S rRNA gene primers previously used for polymerase chain reaction (PCR) detection of methanogenic Archaea from a variety of environments were evaluated by in silico testing. The primers displayed variable coverage of the four main orders of methanogens, highlighting the importance of this type of primer evaluation.