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Boreal forests – a joker in the climate change game? Anders Lindroth

Boreal forests – a joker in the climate change game? Anders Lindroth Department of Physical Geography and Ecosystem Analysis Anders.Lindroth@nateko.lu.se www.lucci.lu.se. Outline. C-sinks in forest ecosystems – how does it work? Today’s role of forests What are the risks? Opportunities?

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Boreal forests – a joker in the climate change game? Anders Lindroth

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  1. Boreal forests – a joker in the climate change game? Anders Lindroth Department of Physical Geography and Ecosystem Analysis Anders.Lindroth@nateko.lu.se www.lucci.lu.se

  2. Outline • C-sinks in forest ecosystems – how does it work? • Today’s role of forests • What are the risks? • Opportunities? • The climate systems’ wish-list up to 2020 Anders Lindroth, Lunds universitet

  3. Principles of forest C-balance NEE = Net ecosystem exchange of CO2= Photosynthesis + Respiration NEE (-) (+) (+) Photosynthesis Autotrophic respiration Heterotrophic respiration Litterfall DOC Root litter Soil carbon = particulate flow = gas flow Anders Lindroth, Lunds universitet

  4. New technology: Ultrasonic anemometer, gas analyzer, computer,in situ, high time resolution (half-hour)) Emission to the atmosphere Uptake from the atmosphere This years result! Measurements Continuousmeasurements Summation over time Anders Lindroth, Lunds universitet

  5. We need towers to deploy our instruments abovethe canopies!

  6. Emission Net Uptake Exemple of annual C-balance in an 30-year-old pine forest in Småland Anders Lindroth, Lunds universitet

  7. Perturbation of Global Carbon Budget (1850-2006) 2000-2006 fossil fuel emissions 7.6 Source deforestation 1.5 CO2 flux (Pg C y-1) atmospheric CO2 4.1 Sink land 2.8 50%? ocean 2.2 Time (y) Le Quéré, unpublished; Canadell et al. 2007, PNAS

  8. …..and in Sweden Ca 29 M ton C (models, fluxdata, inventory data) 18 M ton C = 11 M ton C ( 40 M ton CO2 cf.Sweden’s total emissionof CO2  65 M ton CO2) Anders Lindroth, Lunds universitet

  9. Clearcut Sweden Clearcut Fance Risks & threats So, are disturbances joker no 1?

  10. Opportunities • Changed management practicies • Speeding up processes • More efficient land use

  11. Age & management effects • How does disturbance caused by, e.g, clear-cut (and possible soil treatment) affect the C-balance of forests over a rotation period? • How does the net ecosystem exchange vary over time? • What is the optimum time for harvest seen from maximum C-uptake?

  12. Net carbon uptake as a function of age (and management)in ’clear-cut’ forestry Stand age (yrs) Anders Lindroth, Lunds universitet

  13. Loss of carbon duringthe first 10-15 years Stand age (yrs) Anders Lindroth, Lunds universitet

  14. Initial losses compensated for after 20-30 years Anders Lindroth, Lunds universitet

  15. Average uptake isca 50% of the maximum So, is changed silviculture joker no. 2? Stand age (yrs) • Conclusions • It does exist a potential to increase the sink (by reducing emissions) – but can it be utilized? • Increase from 50 to 60% corresponds 15% Swedens emissions Anders Lindroth, Lunds universitet

  16. Speeding up (and slowing down) processes N! Anders Lindroth, Lunds universitet

  17. 1 kg N = 210 kg C (Magnani et al., 2007. Nature 447 doi:10.1038/nature05847) Anders Lindroth, Lunds universitet

  18. N-efficiency extrapolated to a ’dose’ of 10 kg ha-1: 88 kg C/kg N 188 kg C/kg N N fertilization – efficiency is increasing with smaller amounts! (Data från T. Persson SLU) Anders Lindroth, Lunds universitet

  19. Conclusions: • Fertilization particularly effective at low doses - increased possibilities to avoid negative impacts! • Setting aside 2 M ha for low dose fertilization could increase the sink corresponding to 10% of Swedens emissions! • Creates conflicts of interest – but maybe we have to make a choise? So, is N joker no. 3? Anders Lindroth, Lunds universitet

  20. More efficient use of the land NECC Nordic Centre for studies ofecosystem carbon excange and climateinteractions Anders Lindroth, Lunds universitet

  21. Ranking Anders Lindroth, Lunds universitet

  22. Ranking Anders Lindroth, Lunds universitet

  23. Short-rotation forests? CO2 uptake x 5-10 So, is short-rotation forestry joker no. 4? x 2-3 Anders Lindroth, Lunds universitet

  24. The climate systems’ wish-list up to 2020: • Short-term • Prioritise actions that quickly raises the C-uptake per unit of land-area (short-rotation forests & fertilization)! • Avoid actions with low climate efficiency such as e.g. ethanol - better to plant more efficient ’uptakers’and use products for substitution • Avoid unnecessary emissions from bio-residuals • Long-term • Subsitution of fossil fuels with forest residuals is positive but no quick fix! • Changing silviculture to reduce unnecessary emissions (requires a lot of research) Anders Lindroth, Lunds universitet

  25. N – joker (no. 3) Disturbance (no. 1) Who are the winners? In Sweden: Globally:

  26. Short-rotation forestry (no.4) Changed silviculture (no. 2) Who are the losers? In Sweden & globally:

  27. Thanks for listening! Anders Lindroth, Lunds universitet

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