Policy perils of ignoring uncertainty in oil palm research

Abstract

Success of the emerging Low Emissions Development paradigm in Southeast Asia depends on mitigating impacts of oil palm (OP) expansion on carbon-dense ecosystems, especially tropical peatlands. To this end, Koh et al. (1) ) (3, 4). We estimate belowground C flux (annualized burning, oxidation, and foregone sequestration) as 15.3-26.9 million MgC ha −1 y −1 , ≈300-400% higher than the mean flux reported by the authors. Their unique use of radar to map OP advances RS methods for regional land-cover inventories. However, this method is inadequate for monitoring "future land-use change driven by oilpalm" to "facilitate. . .sustainable development." In Indonesia, the ≈4.97 million ha of mature plantations mapped by Koh et al. in 2010 missed ≈2.7 million ha of OP evidently too young (<8 y) or in patches too small (<200 ha) to be detected with their methods. RSbased OP monitoring must identify OP expansion in real-time and at spatial resolution commensurate with OP development patterns [e.g., Landsat, Satellite Pour l'observation de la Terre (SPOT)].Finally, the authors markedly overstated potential for rehabilitating ≈2.3 million ha of "clear-felled peatlands." First, most "cleared" areas may already be planted with OP. Recent work in Sarawak (www.sarvision.nl) shows that 65% of peatlands deforested from 2005 to 2010 were planted to OP and are unavailable for restoration. Additionally, rehabilitating deforested tropical peatlands is far more difficult and costly than appreciated (5). Enormous investments are required to raise water levels, control fires, and replant native species within the complex sociopolitical milieu of rural Southeast Asia. Finite dollars for peatland conservation must prioritize protecting forested peatlands, not restoring deforested ones.We laud scientists like Koh et al., who wish to engage policymakers. However, clearly communicating uncertainties and assumptions of policy-oriented research is essential. Instead, the authors oversimplified a complex story, with no sensitivity analysis to explore uncertainty in peatland oxidation emissions or alternative land-cover change pathways preceding OP development. Southeast Asian countries developing emissions reductions strategies face tough choices balancing agricultural expansion with forest protection; proper treatment of uncertainty surrounding emissions from OP will help countries plan for worst-and best-case scenarios and design research aimed at informing policy decisions.

Committed carbon emissions, deforestation, and community land conversion from oil palm plantation expansion in West Kalimantan, Indonesia

“…We assumed that no burning occurs in peatlands planted with oil palm and we did not include peat emissions from draining post-2020. Thus, carbon emissions from oil palm on peatlands were underestimated (22).…”

“…As a result of this extensive deforestation, annual GHG emissions in Indonesia-currently among the top 10 national emitters-are sourced predominantly from land cover/land use change (19). However, the locations, patterns, and land cover sources for oil palm plantation expansion; the extent and distribution of undeveloped oil palm leases pending near-term development; and carbon emissions from oil palm agriculture remain largely undocumented (20)(21)(22).To acquire such datasets for tropical regions requires integrating remote sensing products with interdisciplinary methods and analyses (15). Although optical remote sensing satellites such as Landsat have sufficient temporal (∼20 d) and spatial (≤30 m) resolution to detect small land cover patches and punctuated land cover change, they are hampered by cloud cover and cannot be used to map carbon stocks (23,24).…”

“…As a result of this extensive deforestation, annual GHG emissions in Indonesia-currently among the top 10 national emitters-are sourced predominantly from land cover/land use change (19). However, the locations, patterns, and land cover sources for oil palm plantation expansion; the extent and distribution of undeveloped oil palm leases pending near-term development; and carbon emissions from oil palm agriculture remain largely undocumented (20)(21)(22).…”

Reply to Paoli et al.: Explicit consideration of model uncertainties

“…Paoli et al (1) raise some interesting criticisms of our article (2), but we think that they misinterpret important elements of our study, ignore our consideration of model uncertainties, and fail to recognize the wider significance of our work.…”

Restoration planning of degraded tropical forests for biodiversity and ecosystem services

“…We spatially stratified parameters used in the models (i.e. existing land cover class, mineral or peat soils and peat depth) to allow for better accuracy and to reduce uncertainty (Paoli et al, 2011). For oil-palm plantations occurring on mineral soils, carbon loss was estimated as the loss of above-ground biomass (AGB) of existing vegetation during land clearing while gain was calculated as AGB stored in oil-palm plantations (Equation 5.1).…”