Drivers of atmospheric methane uptake by montane forest soils in the southern Peruvian Andes

Sam P. Jones, Torsten Diem, Lidia P. Huaraca Quispe, Adan J. Cahuana, Dave S. Reay, Patrick Meir, Yit Arn Teh

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14 Citations (Scopus)
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Abstract

The soils of tropical montane forests can act as sources or sinks of atmospheric methane (CH4). Understanding this activity is important in regional atmospheric CH4 budgets given that these ecosystems account for substantial portions of the landscape in mountainous areas like the Andes. We investigated the drivers of net CH4 fluxes from premontane, lower and upper montane forests, experiencing a seasonal climate, in south-eastern Peru. Between February 2011 and June 2013, these soils all functioned as net sinks for atmospheric CH4. Mean (standard error) net CH4 fluxes for the dry and wet season were −1.6 (0.1) and −1.1 (0.1) mg CH4-C m−2 d−1 in the upper montane forest, −1.1 (0.1) and −1.0 (0.1) mg CH4-C m−2 d−1 in the lower montane forest, and −0.2 (0.1) and −0.1 (0.1) mg CH4-C m−2 d−1 in the premontane forest. Seasonality in CH4 exchange varied among forest types with increased dry season CH4 uptake only apparent in the upper montane forest. Variation across these forests was best explained by available nitrate and water-filled pore space indicating that nitrate inhibition of oxidation or diffusional constraints imposed by changes in water-filled pore space on methanotrophic communities may represent important controls on soil–atmosphere CH4 exchange. Net CH4 flux was inversely related to elevation; a pattern that differs to that observed in Ecuador, the only other extant study site of soil–atmosphere CH4 exchange in the tropical Andes. This may result from differences in rainfall patterns between the regions, suggesting that attention should be paid to the role of rainfall and soil moisture dynamics in modulating CH4 uptake by the organic-rich soils typical of high-elevation tropical forests.
Original languageEnglish
Pages (from-to)4151-4165
Number of pages15
JournalBiogeosciences
Volume13
Issue number14
DOIs
Publication statusPublished - 21 Jul 2016

Bibliographical note

Acknowledgements. This study is a product of the Andes
Biodiversity and Ecosystem Research Group consortium
(http://www.andesconservation.org/). The authors would like
to acknowledge the agencies that funded this research; the UK Natural
Environment Research Council (NERC; joint grant references
NE/G018278/1, NE/H006583, NE/H007849 and NE/H006753) and
the Norwegian Agency for Development Cooperation (Norad; via a
sub-contract to Yit Arn Teh managed by the Amazon Conservation
Association). Patrick Meir was also supported by an Australian
Research Council Fellowship (FT110100457). Javier Eduardo Silva
Espejo, Walter Huaraca Huasco and the ABIDA NGO provided
critical fieldwork and logistical support. Angus Calder, Michael
Mcgibbon, Vicky Munro and Nick Morley provided invaluable
laboratory support. Thanks to Adrian Tejedor and the Amazon
Conservation Association (http://www.amazonconservation.org/),
who provided assistance with access and plot selection at Hacienda
Villa Carmen. This publication is a contribution from
the Scottish Alliance for Geoscience, Environment and Society
(http://www.sages.ac.uk).

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