Swedish University of Agricultural Sciences Uncertainty and verification of soil organic carbon...
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Swedish University of Agricultural Sciences www.slu.se Uncertainty and verification of soil organic carbon change estimates Erik Karltun and Carina Ortiz Swedish University of Agricultural Sciences
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Swedish University of Agricultural Scienceswww.slu.se
Uncertainty and verification of soil organic carbon change estimatesErik Karltun and Carina OrtizSwedish University of Agricultural Sciences
Swedish University of Agricultural Scienceswww.slu.se
Carbon in Swedish soilsCarbon in Swedish soils
- The carbon stock of Swedish forest soils estimated at 2000 Mton carbon (DOM and SOC)
- An annual change of 1 ‰ equates to 2 Mton C or 7 Mton CO2, i.e. > 10% of Swedish national GHG emissions
- Soils are both sinks and sources- Reporting needs monitoring and
verification – do we have appropriate tools?
Swedish University of Agricultural Scienceswww.slu.se
• Integrated with the NFI• Total number of sampled plots
c.4500• DOM and SOC sampled
separately• Soil type according to World
Reference Base• Organic soil=Histosols
Forest Soil InventoryForest Soil Inventory
Swedish University of Agricultural Scienceswww.slu.se
B hor sampled
BC sampled
50 cm
0 cm
DOM
C sampled
Interpol.
Interpol.
E hor.
Swedish University of Agricultural Scienceswww.slu.se
90 91 93 9492 95 96 97 0499 00 01 0298 03 05 06 07 08 09
2nd Soil Survey 3rd Soil SurveyNo data
Extrapol. Extrapol.SampledUNFCCC-Kyoto reporting
ResampledInterpolated
Data
Reporting timelineReporting timeline
Swedish University of Agricultural Scienceswww.slu.se
Two views on soil carbon changeTwo views on soil carbon change
1990 1994 1998 2002 2006T
g C
0
500
1000
1500
2000
2500SOC DOM
1990 1994 1998 2002 2006
Tg
C
-2
-1
0
1
2
3
4
5
SOCDOMTOTAL
Swedish University of Agricultural Scienceswww.slu.se
Models – an alternative wayModels – an alternative way
- Carbon pools and carbon pool changes was estimated using to conceptually different dynamic carbon models, Q and Yasso07
- Carbon pool development simulated from 1926 using climate and litter input data
- Uncertainty of model output determined by parameter uncertainty analysis and Monte Carlo simulation methodology
Swedish University of Agricultural Scienceswww.slu.se
500
1000
1500
2000
2500
3000
3500
1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Stå
en
de
sk
og
sv
oly
m –
m3
Källa: Riksskogstaxeringen, SLU
Standing forest volumeStanding forest volume
Swedish University of Agricultural Scienceswww.slu.se
Swedish University of Agricultural Scienceswww.slu.se
Swedish University of Agricultural Scienceswww.slu.se
ConclusionsConclusions- Small changes in the soil pool can have a considerable
impact on the national GHG balance
- Over a timeperiod of more than 10 years both models and measurement indicate that mineral soil is a sink but uncertainty is high
- The possibility to monitor and verify small changes is limited due to method uncertainty
- Soils seem to respond slowly to increase in forest biomass
- Combination of various approaches (measurements, models valuable)
- Uncertainty reporting must be improved – todays reporting of uncertainty is not relevant to LULUCF
