Carbon loss associated with land-use change in tropical peatlands: methods and estimates


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During the past decade, Southeast Asian peat swamp forests have been deforested at double the rate of any other forest type. This deforestation is driven by wood production and demand for land on which to establish agriculture, including oil palm and timber plantations. In this presentation given in Vietnam on September 2011 at the annual REDD-ALERT meeting, CIFOR scientist Kristell Hergoualc'h shows how she and other CIFOR scientists assessed carbon losses from wildfires and land conversion in virgin peat swamp forests. They found that peat carbon loss contributes more than 63% to total carbon loss, demonstrating the urgent need to protect tropical peat swamp forests from land-use change and fires in the fight against climate change.

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Carbon loss associated with land-use change in tropical peatlands: methods and estimates

  1. 1. Carbon loss associated with land-use changein tropical peatlands: methods and estimates Kristell Hergoualc’hTHINKING beyond the canopy 29 September 2011 – REDD-ALERT annual meeting, Da Lat, Vietnam
  2. 2. Methodological approachesStock change approach Flux change approach Before After Before After Cin F Cout F Cin OP Cout OP CF COP ΔCF ΔCOP = Cin F – Cout F = Cin OP – Cout OPC loss = CF - COP C loss rate = ΔCF - ΔCOPC loss rate = C loss / life time C loss = C loss rate × life time THINKING beyond the canopy
  3. 3. Carbon loss estimatesLiterature review Southeast Asian peatlands C stocks, peat C fluxes 56 studiesTwo publications Murdiyarso D, Hergoualch K & Verchot LV 2010, ‘Opportunities for reducing greenhouse gas emissions in tropical peatlands’, PNAS, vol 107, no 46, pp. 19655-19660 Hergoualc’h K & Verchot LV 2011, ‘Stocks and fluxes of carbon associated with land-use change in Southeast Asian tropical peatlands: a review’, Global Biogeochemical Cycles, vol 25, GB2001. THINKING beyond the canopy
  4. 4. Carbon loss from wildfiresStock change approachLand-use type C stock loss (Mg C ha-1)before fire Burnt vegetation Burnt peat TotalIntact forest 152 ± 36 285 ± 67 436 ± 77Logged forest 35 ± 36 285 ± 67 320 ± 77Oil palm plantation 32 ± 9 285 ± 67 316 ± 67Acacia plantation 28 ± 2 285 ± 67 313 ± 68C loss: 65 – 90% from peat THINKING beyond the canopy
  5. 5. Peat forest conversion to oil palmCombination of the two methodological approachesStock change approach: Aboveground biomass C lossFlux change approach: Peat C lossPeat C stock changes: Difficulties and Limits Peat depth (up to 20 m), compaction, limited number profiles Presence logs, high water table level  bulk density? How to select the right ‘before land use change’ site? How to address peat compaction, shrinkage and decomposition caused by land-use change? THINKING beyond the canopy
  6. 6. C fluxes into and out of the peat Heterotrophic soil Litterfall respiration CH4 Land clearing fireRoot mortality Soluble & physical removalHeterotrophic soil respiration = peat oxidation = peat decompositionHeterotrophic soil respiration = Total soil respiration - root respiration THINKING beyond the canopy
  7. 7. Peat C balances in the forest and in the oil palm plantation Before AfterLitterfall 7.4 Soil heterotrophic respiration 6.9 CH4 0.03 Soil heterotrophic respiration 9.3Root mortality 1.5 Land clearing fire 4.5 Soluble & Litterfall 1.5 Physical CH4 -0.0002 Removal 1 Root mortality 3.6 Soluble & Physical Removal 1 Cpeat F = Cin peat – Cout peat Cpeat OP = Cin peat – Cout peat = 1.0 Mg C ha-1 y-1 = - 9.8 Mg C ha-1 y-1 = 25 Mg C ha-1 25 y =THINKING Mg C ha-1 25 y - 245 beyond the canopy
  8. 8. Peat forest conversion to oil palm plantation Before AfterCpeat F = 25 Mg C ha-1 25 y Cpeat OP = - 245 Mg C ha-1 25 y - 270 Mg C ha -1 25 yCAbvgrnd biomass F = 182 Mg C ha-1 CAbvgrnd biomass OP = 24 Mg C ha-1 -158 Mg C ha-1 25 y C loss = 428 Mg C ha-1 over 25 years  C loss: 63 % from peat THINKING beyond the canopy
  9. 9. Conclusions Very large carbon loss C loss: 60-90% from the peat REDD mechanism should prioritise peat swamp forests Gaps knowledge on C cycle in tropical peatlands Greenhouse gas accounting methods: heterotrophic soil respiration (N inputs), allometric models specific to peat swamp forestsGeneral misunderstanding : Peat heterotrophic soil respiration  Peat C loss N2O: Global warming potential 300 Increase in N2O emissions due to land-use change in tropical peatlands? THINKING beyond the canopy
  10. 10. Thank CIFOR advances human well-being, environmental conservation, and equity by conducting research to inform policies and practices that affect forests in developing countries. THINKING beyond the canopy