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Lookup NU author(s): Professor Yit Arn TehORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Need for regional economic development and global demand for agro-industrial commodities has resulted in large-scale conversion of forested landscapes to industrial agriculture across South East Asia. However, net emissions of CO2 from tropical peatland conversions may be significant and remain poorly quantified, resulting in controversy around the magnitude of carbon release following conversion. Here we present long term, whole ecosystem monitoring of carbon exchange from two oil palm plantations on converted tropical peat swamp forest. Our sites compare a newly converted oil palm plantation (OPnew) to a mature oil palm plantation (OPmature) and combine them in the context of existing emission factors. Mean annual net emission (NEE) of CO2 measured at OPnew during the conversion period (137.8 Mg CO2 ha-1 yr -1) were an order of magnitude lower during the measurement period at OPmature (17.5 Mg CO2 ha-1 yr-1). However, mean water table depth (WTD) was shallower (0.26 m) than a typical drainage target of 0.6 m suggesting our emissions may be a conservative estimate for mature plantations, mean WTD at OPnew was more typical at 0.54 m. Reductions in net emissions were primarily driven by increasing biomass accumulation into highly productive palms. Further analysis suggested annual peat carbon losses of 24.9 Mg CO2-C ha-1 yr-1 over the first 6 years, lower than previous estimates for this early period from subsidence studies, losses reduced to 12.8 Mg CO2-C ha-1 yr-1 in the later, mature phase. Despite reductions in NEE and carbon loss over time, the system remained a large net source of carbon to the atmosphere after 12 years with the remaining 8 years of a typical plantation?s rotation unlikely to recoup losses. These results emphasise the need for effective protection of tropical peatlands globally and strengthening of legislative enforcement where moratoria on peatland conversion already exist.
Author(s): McCalmont J, Kho LK, Teh YA, Lewis K, Chocholek M, Rumpang E, Hill TC
Publication type: Article
Publication status: Published
Journal: Global Change Biology
Year: 2021
Volume: 27
Issue: 11
Pages: 2361-2376
Print publication date: 01/06/2021
Online publication date: 02/02/2021
Acceptance date: 08/01/2021
Date deposited: 04/12/2024
ISSN (print): 1354-1013
ISSN (electronic): 1365-2486
Publisher: Wiley-Blackwell Publishing Ltd.
URL: https://doi.org/10.1111/gcb.15544
DOI: 10.1111/gcb.15544
Data Access Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.
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