US Forests and Carbon Storage

1. US Forests and Carbon Storage Michael G. Ryan USDA Forest Service Rocky Mountain Research Station mgryan@fs.fed.us http://lamar.colostate.edu/~mryan Richard A. Birdsey, USDA FS, NRS Christian P. Giardina, USDA FS PSW Stith T. Gower, University of Wisconsin Mark Harmon, Oregon State University Linda Heath, USDA FS, NRS Richard A. Houghton, Woods Hole Research Center Robert Jackson, Duke University Duncan Mckinley, AAAS Brian Murray, Duke University Mark Nechodom, USDA Diane Pataki, University of California, Irvine GHG Modeling Workshop, Shepherdstown, WV 4/6 -4/9, 2009

2. Synthesis of Science • Issues in Ecology – ESA synthesis for policy and managers; Ecological Applications – Review paper Questions • Can forests do more to slow CO2 increase? • Why are US forests a sink? • Will they remain that way? Will our actions enhance it? For how long? • Can we measure it well enough to give it value?

3. US forests and long-lived wood products offset about 12-20% of fossil-fuel emissions North America Mt = (1012 g) CCSP, 2007. The First State of the Carbon Cycle Report (SOCCR): The North American Carbon Budget and Implications for the Global Carbon Cycle. From SOCCR Report: http://www.climatescience.gov

4. 10% is Huge! • To get another 10%: • Convert entire US auto fleet to hybrid gas mileage • Convert 1/3 current Ag land to forests.

5. Why the Uncertainty? • SOCCR Report includes large estimates for carbon stored in soil (highly uncertain). • Woodbury et al (2007) has a much lower rate for carbon stored in soil.

6. Forest carbon has a cycle: after disturbance, loss and recovery Photo by National Park Service Photo by Mike Ryan Photo by Dan Kashian Photo by Mike Ryan

7. Ecosystems that regenerate forests after disturbance (harvesting, fire, bugs) will recover all of the carbon lost

8. The larger the landscape, the more stable the carbon seems

9. How Does Fire Change Forest Carbon? Fire kills trees, it doesn’t consume them; Fire losses of foliage and forest floor are only ~10-20% of the site carbon Photo by Dan Kashian Photo by AZ Dept Emergency Mgmt

10. What happens with no regeneration? Example: Hayman Fire, Colorado, 2002 Photo by Merrill Kaufmann, USFS

11. What about MPB Outbreak? Example: Colorado, 1998-? Photo by Merrill Kaufmann, USFS

12. Large temporary carbon source over a large area

13. Estimated losses of carbon are ~16 x 1012 gC yr-1 Compared to 27 x 1012 gC yr-1 for fires for all of Canada average 1959-1999 But, the ecosystem C recovers the carbon lost as the trees regrow

14. Forest Ecology – Bottom Line • Disturbance does not cause C loss, unless forest does not regenerate • Carbon is best evaluated over large scales of space and time • The timing isn’t important Photo by Mike Ryan

15. Timing is important for economics and our descendents: YNP

16. Can forests do more to slow the rate of CO2 increase in the air’?

17. Keep forests as forests: Avoid deforestation • Urban/exurban development, conversion to ag use. Important for US, not just tropics • Large potential, low risk, but difficult to credit • No uncertainty about C value, Large uncertainty about US amount • Benefits: • Many co-benefits. • Adverse: • None

18. Afforestation, especially in restoration • Moderate potential, low risk • Benefits: • Depends on how it is done! • Increased biodiversity and soil erosion control • Adverse: • More water use • Loss of ag production • Uncertainties low when re-establishing forests

19. Management: Decrease Outputs (Increase rotation, decrease removals) • Large potential, but must be in areas with active forest management, moderate risk • Risks: increased risk of disturbance loss • Benefits: • Increase structural and bio-diversity • Adverse: • Lower economic return? • Alter species composition?

20. Avoided deforestation: Highest potential, lowest risk Potential decreases; Risk or uncertainty increases with other options

21. US Forest Carbon Balance 1800-1950: Forest Disturbance on a Massive Scale-the Industrial Revolution In 1915, emissions from forests were 760 million tons C per year ? Birdsey, R., K. Pregitzer, and A. Lucier. 2006. Forest carbon management in the United States: 1600-2100. Journal of Environmental Quality 35:1461-1469. Photo courtesy of University of Washington Libraries, Special Collections, KIN084.

22. US Forest Carbon Balance 1950 to 2008: Forest Regrowth on a Massive Scale In 2000, sequestration by forests was ~200 million tons C per year Birdsey, R., K. Pregitzer, and A. Lucier. 2006. Forest carbon management in the United States: 1600-2100. Journal of Environmental Quality 35:1461-1469. Photo by Mike Ryan

23. Consequences of Sink Saturation If the Sink is a Result of: Past and current land use change (forest regrowth, woody encroachment Physiological response (CO2 ornitrogen deposition Sink Strength of US Forests Sink Strength of US Forests We are here Time Time Climate will warm as predicted Climate will warm more rapidly than predicted Canadell, J. G., D. E. Pataki, R. Gifford, R. A. Houghton, Y. Luo, M. R. Raupach, P. Smith, and W. Steffen. 2007. Saturation of the terrestrial carbon sink. Pages 59-78 in J. G. Canadell, D. E. Pataki, and L. F. Pitelka, editors. Terrestrial ecosystems in a changing world. Springer-Verlag, Berlin.

24. Largest Sources of Uncertainty • Current Estimates: • Changes in soil C and dead wood • Land use changes • Disturbance area • Future Estimates • Pace of disturbance, regeneration, recovery • Sink saturation

25. The Gorilla in the Room:Tropical Deforestation • 1-2 Petagrams (1015 g)/year – about the same as US fossil fuel emissions

26. Take Home • Forest Carbon is a cycle:Forests recover what is lost in disturbance if they regenerate • We have a large sink, but it may not last • From a forest ecology perspective: • Keep forests • Restore forests • Encourage regeneration after disturbance NRS Global Change

27. Further Reading • Ryan, Michael G. 2008. Forests and Carbon Storage. (June 04, 2008). U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. http://www.fs.fed.us/ccrc/topics/carbon.shtml • Effects of climate change on agriculture, land resources, water resources and biodiversity http://www.climatescience.gov/Library/sap/sap4-3/final-report/default.htm • State of the Carbon Cycle Report http://cdiac.ornl.gov/SOCCR/ • Carbon and Yellowstone Fires: http://lamar.colostate.edu/~mryan/Publications/Kashian_Romme_Tinker_Turner_Ryan_2006_Bioscience_56_598-606.pdf and http://lamar.colostate.edu/~mryan/Publications/Final_Report_JFSP_03-1-1-06.pdf • US Greenhouse Gas Inventory: http://www.epa.gov/climatechange/emissions/usinventoryreport.html • Jackson, R.B., Schlesinger, W.H., 2004. Curbing the U.S. carbon deficit. Proceedings of the National Academy of Science 101, 15827–15829. • Jackson, R.B., Jobbagy, E.G., Avissar, R., Roy, S.B., Barrett, D.J., Cook, C.W., Farley, K.A., le Maitre, D.C., McCarl, B.A., Murray, B.C., 2005. Trading water for carbon with biological sequestration. Science 310, 1944-1947. • Birdsey, R., Pregitzer, K., Lucier, A., 2006. Forest carbon management in the United States: 1600-2100. Journal of Environmental Quality 35, 1461-1469.