Tree stem bases are sources of CH4 and N2O in a tropical forest on upland soil during the dry to wet season transition

Welch, Bertie and Gauci, Vincent and Sayer, Emma Jane (2019) Tree stem bases are sources of CH4 and N2O in a tropical forest on upland soil during the dry to wet season transition. Global Change Biology, 25 (1). pp. 361-372. ISSN 1354-1013

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Abstract

Tropical forests on upland soils are assumed to be a methane (CH4) sink and a weak source of nitrous oxide (N2O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH4, and recent evidence from temperate woodlands suggests that tree stems can also emit N2O. Here, we measured CH4 and N2O fluxes from the soil and from tree stems in a semi‐evergreen tropical forest on upland soil. To examine the influence of seasonality, soil abiotic conditions and substrate availability (litter inputs) on trace greenhouse gas (GHG) fluxes, we conducted our study during the transition from the dry to the wet season in a long‐term litter manipulation experiment in Panama, Central America. Trace GHG fluxes were measured from individual stem bases of two common tree species and from soils beneath the same trees. Soil CH4 fluxes varied from uptake in the dry season to minor emissions in the wet season. Soil N2O fluxes were negligible during the dry season but increased markedly after the start of the wet season. By contrast, tree stem bases emitted CH4 and N2O throughout the study. Although we observed no clear effect of litter manipulation on trace GHG fluxes, tree species and litter treatments interacted to influence CH4 fluxes from stems and N2O fluxes from stems and soil, indicating complex relationships between tree species traits and decomposition processes that can influence trace GHG dynamics. Collectively, our results show that tropical trees can act as conduits for trace GHGs that most likely originate from deeper soil horizons, even when they are growing on upland soils. Coupled with the finding that the soils may be a weaker sink for CH4 than previously thought, our research highlights the need to reappraise trace gas budgets in tropical forests.

Item Type: Journal Article
Journal or Publication Title: Global Change Biology
Additional Information: This is the peer reviewed version of the following article: Welch, B., Gauci, V., Sayer, E.J., (2019), Tree stem bases are sources of CH4 and N2O in a tropical forest on upland soil during the dry to wet season transition. Global Change Biology. doi: 10.1111/gcb.14498 which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14498 This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/2300/2304
Subjects:
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 128475
Deposited By: ep_importer_pure
Deposited On: 23 Oct 2018 07:40
Refereed?: Yes
Published?: Published
Last Modified: 20 Sep 2019 01:56
URI: https://eprints.lancs.ac.uk/id/eprint/128475

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