Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel

Meijide, Ana; Rúa, Cristina de la; Guillaume, Thomas; Röll, Alexander; Hassler, Evelyn; Stiegler, Christian; Tjoa, Aiyen; June, Tania; Corre, Marife D.; Veldkamp, Edzo; Knohl, Alexander

doi:10.1038/s41467-020-14852-6

Cited by 63 publications

(44 citation statements)

References 74 publications

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“…Annual emission in oil palm plots (5.0 ± 3.7 kg N 2 O ha −1 year −1 ) was above IPCC default value for oil palm plantations on peat (1.2 kg N 2 O ha −1 year −1 , Drösler et al, 2014). Assessments of annual N 2 O emissions in oil palm plantations on peat (Melling et al, 2007;Sakata et al, 2015;Oktarita et al, 2017;Chaddy et al, 2019;Meijide et al, 2020) indicate much higher rates (32 ± 2 kg N 2 O ha −1 year −1 , n 8) than our result and IPCC default value. They also vary greatly according to site, management practices (tillage/no tillage or use of coated vs. conventional nitrogen fertilizers) (Sakata et al, 2015) and presence of hot spots (Oktarita et al, 2017).…”

Section: Spatio-temporal Variability and Controls Of N 2 O Fluxcontrasting

confidence: 66%

“…They also vary greatly according to site, management practices (tillage/no tillage or use of coated vs. conventional nitrogen fertilizers) (Sakata et al, 2015) and presence of hot spots (Oktarita et al, 2017). Emission rates in OP-2007 andOP-2009 were in the range of flux reported by Melling et al (2007) while emissions in OP-2011 were closer to but lower than values reported by Sakata et al (2015), Oktarita et al (2017), Chaddy et al (2019) and Meijide et al (2020). Lower average emission at our site as compared to the literature may arise from low supply of labile carbon as indicated by the ratio of recalcitrant aromatic compounds to labile aliphatic compounds in soil organic matter (Swails et al, 2018) and also potentially from water table levels higher ( Supplementary Table S3) than on average (65 cm, Hergoualc'h and .…”

Section: Spatio-temporal Variability and Controls Of N 2 O Fluxmentioning

confidence: 84%

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Spatio-Temporal Variability of Peat CH4 and N2O Fluxes and Their Contribution to Peat GHG Budgets in Indonesian Forests and Oil Palm Plantations

Swails

Hergoualc’h

Verchot

et al. 2021

Front. Environ. Sci.

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Land-use change in tropical peatlands substantially impacts peat emissions of methane (CH4) and nitrous oxide (N2O) in addition to emissions of carbon dioxide (CO2). However, assessments of full peat greenhouse gas (GHG) budgets are scarce and CH4 and N2O contributions remain highly uncertain. The objective of our research was to assess changes in peat GHG flux and budget associated with peat swamp forest disturbance and conversion to oil palm plantation and to evaluate drivers of variation in trace gas fluxes. Over a period of one and a half year, we monitored monthly CH4 and N2O fluxes together with environmental variables in three undrained peat swamp forests and three oil palm plantations on peat in Central Kalimantan. The forests included two primary forests and one 30-year-old secondary forest. We calculated the peat GHG budget in both ecosystems using soil respiration and litterfall rates measured concurrently with CH4 and N2O fluxes, site-specific soil respiration partitioning ratios, and literature-based values of root inputs and dissolved organic carbon export. Peat CH4 fluxes (kg CH4 ha−1 year−1) were insignificant in oil palm (0.3 ± 0.4) while emissions in forest were high (14.0 ± 2.8), and larger in wet than in dry months. N2O emissions (kg N2O ha−1 year−1) were highly variable spatially and temporally and similar across land-uses (5.0 ± 3.9 and 5.2 ± 3.7 in oil palm and forest). Temporal variation of CH4 was controlled by water table level and soil water-filled pore space in forest and oil palm, respectively. Monthly fluctuations of N2O were linked to water table level in forest. The peat GHG budget (Mg CO2 equivalent ha−1 year−1) in oil palm (31.7 ± 8.6) was nearly eight times the budget in forest (4.0 ± 4.8) owing mainly to decreased peat C inputs and increased peat C outputs. The GHG budget was also ten times higher in the secondary forest (10.2 ± 4.5) than in the primary forests (0.9 ± 3.9) on the account of a larger peat C budget and N2O emission rate. In oil palm 96% of emissions were released as CO2 whereas in forest CH4 and N2O together contributed 65% to the budget. Our study highlights the disastrous atmospheric impact associated with forest degradation and conversion to oil palm in tropical peatlands and stresses the need to investigate GHG fluxes in disturbed undrained lands.

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Section: Spatio-temporal Variability and Controls Of N 2 O Fluxcontrasting

confidence: 66%

Section: Spatio-temporal Variability and Controls Of N 2 O Fluxmentioning

confidence: 84%

Spatio-Temporal Variability of Peat CH4 and N2O Fluxes and Their Contribution to Peat GHG Budgets in Indonesian Forests and Oil Palm Plantations

Swails

Hergoualc’h

Verchot

et al. 2021

Front. Environ. Sci.

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“…Only very recently have studies using EC started to report net carbon flux from oil palm plantations (Meijide et al, 2020), with only one monitoring oil palm cultivation on tropical peat (Kiew et al, 2020). The Kiew et al (2020) study monitored a mature oil palm plantation on peatland in Sarawak, Malaysia and reported a mean annual net emission of 36.4 Mg CO 2 ha −1 year −1 , three times the Meijide et al (2020) estimate for oil palm on mineral soils and double the emissions seen in even the most disturbed PSF reported in Hirano et al (2012). Kiew et al (2020) echoed Meijide et al (2020) in calling for more EC studies on peatland plantations, particularly in the early years of conversion where net emissions are expected to be at their highest but are, as yet, unreported.…”

Section: Introductionmentioning

confidence: 99%

“…Kiew et al (2020) echoed Meijide et al (2020) in calling for more EC studies on peatland plantations, particularly in the early years of conversion where net emissions are expected to be at their highest but are, as yet, unreported. The implications of this lack of EC monitoring of different age classes of peatland oil palm is significant; Meijide et al (2020) state they were unable to perform a full carbon life cycle assessment (LCA) as a result, despite the need for better quantification being highlighted in earlier LCA studies of palm oil production (Mattsson et al, 2000; Schmidt, 2015).…”

Section: Introductionmentioning

confidence: 99%

Short‐ and long‐term carbon emissions from oil palm plantations converted from logged tropical peat swamp forest

McCalmont

Kho

Teh

et al. 2021

Global Change Biology

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Need for regional economic development and global demand for agro‐industrial commodities have 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 year−1) was an order of magnitude lower during the measurement period at OPmature (17.5 Mg CO2 ha−1 year−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 year−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 year−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 emphasize the need for effective protection of tropical peatlands globally and strengthening of legislative enforcement where moratoria on peatland conversion already exist.

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“…For example, studies assuming palm oil cultivation on tropical forest and/or peat land in Malaysia and Indonesia estimated DLUC emissions in the range of 150–530 g CO 2 eq. MJ −1 [ 64 , 69 , 70 , 124 ]. On the other hand, studies on palm oil in Colombia and Thailand considered increase in the carbon stock due to LUC, assuming that the expansion of oil palm cultivation would occur in shrublands, savannahs, paddy fields and other agricultural lands [ 52 , 56 , 71 ].…”

Section: Environmental Impacts Of Biofuelsmentioning

confidence: 99%

Environmental sustainability of biofuels: a review

2020

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Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can—on average—have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

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Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel

Cited by 63 publications

References 74 publications

Spatio-Temporal Variability of Peat CH4 and N2O Fluxes and Their Contribution to Peat GHG Budgets in Indonesian Forests and Oil Palm Plantations

Spatio-Temporal Variability of Peat CH4 and N2O Fluxes and Their Contribution to Peat GHG Budgets in Indonesian Forests and Oil Palm Plantations

Short‐ and long‐term carbon emissions from oil palm plantations converted from logged tropical peat swamp forest

Environmental sustainability of biofuels: a review

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