Fluvial organic carbon fluxes from oil palm plantations on tropical peatland
<p>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 Southea...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-12-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/7435/2018/bg-15-7435-2018.pdf |
| Summary: | <p>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<sup>−2</sup> yr<sup>−1</sup> to 57.7 %,
16.3 g C m<sup>−2</sup> yr<sup>−1</sup> (± 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 CO<sub>2</sub> emissions
from the peat surface, in studies of tropical peatland land conversion.</p> |
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| ISSN: | 1726-4170 1726-4189 |