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Fluvial organic carbon fluxes from oil palm plantations on tropical peatland

Lookup NU author(s): Dr Mark Henry Garnett, Professor Yit Arn TehORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

Intact tropical peatlands are dense long-term stores of carbon. However, the future security of these ecosystems is at risk from land conversion and extensive peatland drainage. This can enhance peat oxidation and convert long-term carbon sinks into significant carbon sources. In Southeast Asia, the largest land use on peatland is for oil palm plantation agriculture. Here, we present the first annual estimate of exported fluvial organic carbon in the drainage waters of four peatland oil palm plantation areas in Sarawak, Malaysia. Total organic carbon (TOC) fluxes from the plantation second- and third-order drains were dominated (91 %) by dissolved organic carbon (DOC) and ranged from 34.4 ± 9.7 C m−2 yr−1 to 57.7 %, 16.3 g C m−2 yr−1 (± 95 % confidence interval). These fluxes represent a single-year survey which was strongly influenced by an El Ninõ event and therefore lower discharge than usual was observed. The magnitude of the flux was found to be influenced by water table depth, with higher TOC fluxes observed from more deeply drained sites. Radiocarbon dating on the DOC component indicated the presence of old (pre-1950s) carbon in all samples collected, with DOC at the most deeply drained site having a mean age of 735 years. Overall, our estimates suggest fluvial TOC contributes ∼ 5 % of total carbon losses from oil palm plantations on peat. Maintenance of high and stable water tables in oil palm plantations appears to be key to minimising TOC losses. This reinforces the importance of considering all carbon loss pathways, rather than just CO2 emissions from the peat surface, in studies of tropical peatland land conversion.


Publication metadata

Author(s): Cook S, Whelan MJ, Evans CD, Gauci V, Peacock M, Garnett MH, Kho LK, Teh YA, Page SE

Publication type: Article

Publication status: Published

Journal: Biogeosciences

Year: 2018

Volume: 15

Issue: 24

Pages: 7435-7450

Print publication date: 21/12/2018

Online publication date: 06/12/2018

Acceptance date: 04/12/2018

Date deposited: 13/06/2019

ISSN (print): 1726-4170

ISSN (electronic): 1726-4189

Publisher: Copernicus GmbH

URL: https://doi.org/10.5194/bg-15-7435-2018

DOI: 10.5194/bg-15-7435-2018


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Funding

Funder referenceFunder name
2049.0317
R010913000
X402NE53

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