Assessing GHG Emissions from peatlands      using vegetation as a proxy              John Couwenberg
Peatlands contain a lot of carbonTollund Man, Denmark
drainage mobilises carbon: CO2 (und N2O) emissions                                       Kalimantan, Indonesia
rewetting to reduce emissions                                Peenetal, Germany
Quantifying GHG fluxes:• direct flux measurements (chambers, micrometeorol.)   – combined with indicators / proxies (cf. I...
Measuring over small areas: closed chamber method
For all three GHG (CH4, CO2, N2O)
Measuring over large areas: eddy covariance
Mainly used for CO2, but also for CH4 and N2O
Measurements need to be frequent, long term, intensive
Wide variety of site parameters influencing emissions…peatland types, peat types, spatial heterogeneity,land use, former l...
Measuring is complicated, time consuming, expensive
Measure pilot sites, develop proxiesMeta-analysis: water level main single explanatory variable
CO2 emissions from temperate European peatlandsField measurements: WL is a good proxy                        70           ...
CO2 emissions from temperate European peatlandsSubsidence based emissions: WL is a good proxy                        70   ...
N2O emissions from temperate European peatlandsDirect flux measurements: WL is a good proxy                             10...
CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): WL is a good proxy                 ...
CH4 emissions from tropical and boreal peatlandsDirect flux measurements (hourly flux): WL is a good proxy                ...
Proxy: Water level• many and frequent data necessary• measure a lot (e.g. automatic logger)• modeling using weather data (...
CH4 emissions from temperate European peatlandsWL is not a quantitatively precise proxy                           600     ...
CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): WL + vegetation                    ...
CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): vegetation                         ...
Emissions strongly related to water levelVegetation strongly related to water levelEmissions also related to vegetation U...
Vegetation as indicator of emissions•   Integration of site parameters•   Quick•   Easy•   Cheap•   Reliable … ?          ...
Proxy: Vegetationadvantages• relationship to long-term water level• relationship to other relevant site conditions (nutrie...
Proxy: Vegetationdisadvantages• slow reaction to changing site conditions• must be calibrated for different climate and ph...
Towards GESTs: Vegetation-formsIntegration of flora and environment- Species groups- Presence and absence as indicator    ...
Water level classes (Wasserstufen)     Water level class          long-term median water level (cm)                       ...
GESTs:Greenhouse gas Emission Site Types
Assessing rewetting• N2O fluxes from drained peatlands very erratic• N2O fluxes from rewetted peatlands negligible• N2O fl...
Ostrovskoje: GESTsA: 2009B: 2039 BaselineC: 2039 WiedervernässungA: 7343 t CO2-eq / JB: 7933 t CO2-eq / JC: 3779 t CO2-eq ...
Rewetting• hydrologic analysis necessary: which sub-area will become how wet ?• CH4 emissions may become very high• but un...
Complication: methane spike after rewettingplants not adapted to wet conditions will die off labile carbon pool  anoxic ...
Complication: nutrient enriched soilsLarge methane fluxes may persist (how long ?)                     2005       2006    ...
Peatlands contain a lot of carbonTollund Man, Denmark
peatlands are much more than just carbon…                    • biodiversity                    • water retention          ...
and make it wet !
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Peatland management impacts on carbon/climate regulation - international evidence

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Talk by John Couwenberg at VNN peatland meeting, Leeds 18th January 2012

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Peatland management impacts on carbon/climate regulation - international evidence

  1. 1. Assessing GHG Emissions from peatlands using vegetation as a proxy John Couwenberg
  2. 2. Peatlands contain a lot of carbonTollund Man, Denmark
  3. 3. drainage mobilises carbon: CO2 (und N2O) emissions Kalimantan, Indonesia
  4. 4. rewetting to reduce emissions Peenetal, Germany
  5. 5. Quantifying GHG fluxes:• direct flux measurements (chambers, micrometeorol.) – combined with indicators / proxies (cf. IPCC)• CO2 flux also assessed via stock-change approach – standard approach for e.g. forest, mineral soil) – not practicable for organic soilsorganic soil fluxes are based on direct measurement
  6. 6. Measuring over small areas: closed chamber method
  7. 7. For all three GHG (CH4, CO2, N2O)
  8. 8. Measuring over large areas: eddy covariance
  9. 9. Mainly used for CO2, but also for CH4 and N2O
  10. 10. Measurements need to be frequent, long term, intensive
  11. 11. Wide variety of site parameters influencing emissions…peatland types, peat types, spatial heterogeneity,land use, former land use, abiotic conditions, vegetation…
  12. 12. Measuring is complicated, time consuming, expensive
  13. 13. Measure pilot sites, develop proxiesMeta-analysis: water level main single explanatory variable
  14. 14. CO2 emissions from temperate European peatlandsField measurements: WL is a good proxy 70 60 t CO2·ha-1·y-1 50 40 30 20 10 r2 = 0.68, p < 0.01 0 -10 -140 -120 -100 -80 -60 -40 -20 0 20 40 mean annual water level (cm)after Couwenberg et al. (2011)
  15. 15. CO2 emissions from temperate European peatlandsSubsidence based emissions: WL is a good proxy 70 60 t CO2·ha-1·y-1 50 40 30 20 10 r2 = 0.68, p < 0.01 0 -10 -140 -120 -100 -80 -60 -40 -20 0 20 40 mean annual water level (cm)after Couwenberg et al. (2011): ● direct flux, ● site specific subsidence
  16. 16. N2O emissions from temperate European peatlandsDirect flux measurements: WL is a good proxy 100 80 kg N2O·ha-1·y-1 60 40 20 0 -100 -80 -60 -40 -20 0 20 40 60 mean annual water level (cm)Couwenberg et al. (2011), bog sites, fen sites without fertilizer application, fen sites with fertilizerapplication; x treed sites.
  17. 17. CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): WL is a good proxy 600 500 400 kg CH4·ha-1·y-1 300 200 100 0 -100 -80 -60 -40 -20 0 20 40 mean annual water level (cm)Couwenberg et al. (2011)
  18. 18. CH4 emissions from tropical and boreal peatlandsDirect flux measurements (hourly flux): WL is a good proxy 3CH4 emission [mg m-2 h-1] 15 -0,5 2 10 wood peat SE Asia 1 5 0 0 -100 -80 -60 -40 -20 0 20 -100 -80 -60 -40 -20 0 20 water level [cm]Couwenberg et al. (2010) Tropical; Temperate; ∆ Boreal
  19. 19. Proxy: Water level• many and frequent data necessary• measure a lot (e.g. automatic logger)• modeling using weather data (calibrate, monitor)• WL not yet measurable using remote sensing• particularly for CH4 high uncertainty remains
  20. 20. CH4 emissions from temperate European peatlandsWL is not a quantitatively precise proxy 600 500 400 kg CH4·ha-1·y-1 300 200 100 0 -100 -80 -60 -40 -20 0 20 40 mean annual water level (cm)Couwenberg et al. (2011)
  21. 21. CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): WL + vegetation 600 500 r2 = 0.76, p < 0.01 400 kg CH4·ha-1·y-1 300 200 100 0 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 mean annual water level (cm)Couwenberg et al. (2011), sites with aerenchymous shunt species; sites with open vegetation withoutshunt species; x treed sites.
  22. 22. CH4 emissions from temperate European peatlandsDirect flux measurements (annual flux): vegetation 800 700 600 kg CH4·ha-1·y-1 500 400 300 200 100 0 0 500 1000 1500 2000 2500 aerenchymous leaves (n m-2)After Drösler (2005)
  23. 23. Emissions strongly related to water levelVegetation strongly related to water levelEmissions also related to vegetation Use vegetation as indicator for emissions!
  24. 24. Vegetation as indicator of emissions• Integration of site parameters• Quick• Easy• Cheap• Reliable … ? Greenhouse Gas Emission Site Types (GESTs)
  25. 25. Proxy: Vegetationadvantages• relationship to long-term water level• relationship to other relevant site conditions (nutrient status, pH, land use, …)• influences fluxes itself (substrate quality, aerenchyma)• can be mapped on relevant scale (1:2,500 – 1:10,000)• can be mapped using remote sensing (good for €)
  26. 26. Proxy: Vegetationdisadvantages• slow reaction to changing site conditions• must be calibrated for different climate and phytogeographic regions• not suitable when not there (e.g. ‘black deserts’)
  27. 27. Towards GESTs: Vegetation-formsIntegration of flora and environment- Species groups- Presence and absence as indicator site factor gradient species groups site factor classes 1 2 3 4 5 subunits 1 2 1 2
  28. 28. Water level classes (Wasserstufen) Water level class long-term median water level (cm) wet season dry season7+ upper sublitoral +250 to +140 +250 to +1406+ lower eulitoral +150 to +10 +140 to +05+ wet (upper eulitoral) +10 to -5 +0 to -104+ very moist -5 to -15 -10 to -203+ moist -15 to -35 -20 to -452+ moderately moist -35 to -70 -45 to -852- moderately dry Water supply deficiency: < 60 l/m²3- dry Water supply deficiency: 60–100 l/m²4- very dry Water supply deficiency: 100–140 l/m²5- extremely dry Water supply deficiency: > 140 l/m²
  29. 29. GESTs:Greenhouse gas Emission Site Types
  30. 30. Assessing rewetting• N2O fluxes from drained peatlands very erratic• N2O fluxes from rewetted peatlands negligible• N2O fluxes can only decline upon rewetting• reduction cannot be quantified• disregard N2O: conservative estimate of reductions
  31. 31. Ostrovskoje: GESTsA: 2009B: 2039 BaselineC: 2039 WiedervernässungA: 7343 t CO2-eq / JB: 7933 t CO2-eq / JC: 3779 t CO2-eq / J
  32. 32. Rewetting• hydrologic analysis necessary: which sub-area will become how wet ?• CH4 emissions may become very high• but unlikely higher than previous CO2 emissions
  33. 33. Complication: methane spike after rewettingplants not adapted to wet conditions will die off labile carbon pool  anoxic conditions  methanedirect flux measurements rare or lackingavoid: remove plants, possibly even enriched upper soil
  34. 34. Complication: nutrient enriched soilsLarge methane fluxes may persist (how long ?) 2005 2006 2007kg CH4 ha-1 a-1 2521 4934 2376 additional problem: litter import Augustin & Chojnicki, 2008
  35. 35. Peatlands contain a lot of carbonTollund Man, Denmark
  36. 36. peatlands are much more than just carbon… • biodiversity • water retention • nutrient retention • local cooling • tourism • production (paludicultures) avoid one-dimensional approach to rewetting
  37. 37. and make it wet !

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