US Forests and Carbon Storage Michael G. RyanUSDA Forest ServiceRocky Mountain Research Stationmgryan@fs.fed.ushttp://lamar.colostate.edu/~mryan

GHG Modeling Workshop, Shepherdstown, WV 4/6 -4/9, 2009

Richard A. Birdsey, USDA FS, NRSChristian P. Giardina, USDA FS PSWStith T. Gower, University of WisconsinMark Harmon, Oregon State UniversityLinda Heath, USDA FS, NRSRichard A. Houghton, Woods Hole Research CenterRobert Jackson, Duke UniversityDuncan Mckinley, AAASBrian Murray, Duke UniversityMark Nechodom, USDADiane Pataki, University of California, Irvine

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?

From SOCCR Report: http://www.climatescience.gov

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.

10% is Huge!• To get another 10%:• Convert entire US auto fleet to

hybrid gas mileage• Convert 1/3 current Ag land to

forests.

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.

Forest carbon has a cycle: after disturbance, loss and recovery

Photo by Mike Ryan

Photo by Dan Kashian

Photo by National Park Service

Photo by Mike Ryan

Ecosystems that regenerate forests after disturbance (harvesting, fire,

bugs) will recover all of the carbon lost

Year since fire

0 50 100 150 200 250

Car

bon

(Mg

C/h

a)

0

50

100

150

Carbon inTreesCarbon in

Dead Wood

Total Carbon

Carbon in Soil

Fire

The larger the landscape, the more stable the carbon seems

0

200

400

600

800

1000

1200

1400

0 100 200 300 400

Time (years)

To

tal

C S

tore

s (M

g/h

a)

1 forest stand

10 forest stands

100 forest stands

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

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 Prefire: Total = 16 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 Postfire: Total = 14 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 Prefire: Total = 16 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 100 years postfire: Total = 8 kg C m-2

Lost = 8 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

What happens with no regeneration?Example: Hayman Fire, Colorado, 2002

Photo by Merrill Kaufmann, USFS

What about MPB Outbreak?Example: Colorado, 1998-?

Photo by Merrill Kaufmann, USFS

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 Pre-Beetle: Total = 16 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

Car

bon

Sto

cks

(kg

m-2

)

0

2

4

6

8

10 Post-Beetle: Total = 16 kg C m-2

Soil ForestFloor

DeadWood

FoliageLiveWood

Large temporary carbon source over a large area

But, the ecosystem C recovers the carbon lost as the trees regrow

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

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

Timing is important for economics and our descendents: YNP

-120

-100

-80

-60

-40

-20

0

20

40

1989 2029 2069 2109 2149 2189 2229

Prefire NEP

Total Landscape NEP

Tot

al L

an

dsc

ape

NE

P (

g C

/m2 /

yr- )

-30

-25

-20

-15

-10

-5

0

5

10

Cumulative C Storage

Cu

mu

lative

C S

tora

ge (g/m

2x 1

00

)Recovery of C storage f or Yellowstone Landscape

After 2020, the landscape will be a C sink

But it won’t regain the C lost in combustion andin decomposition of dead trees until ~ 2100

Kashian DM, WH Romme, DB Tinker, MG Turner, and MG Ryan. 2006. Carbon storage on coniferous landscapes with stand-replacing fires. BioScience 7:598-606. Copyright, American Institute of Biological Sciences.

Can forests do more to slow the rate of CO2 increase in

the air’?

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

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

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?

Avoided deforestation: Highest potential, lowest risk

Potential decreases; Risk or uncertainty increases with other

options

US Forest Carbon Balance 1800-1950: Forest Disturbance on a Massive Scale-the Industrial Revolution

-500

0

500

1000

1700 1800 1900 2000 2100

Birdsey, R., K. Pregitzer, and A. Lucier. 2006. Forest carbon management in the United States: 1600-2100. Journal of Environmental Quality 35:1461-1469.

In 1915, emissions from forests were 760 million tons C per year

Photo courtesy of University of Washington Libraries, Special Collections, KIN084.

?

-500

0

500

1000

1700 1800 1900 2000

In 2000, sequestration by forests was ~200 million tons C per year

US Forest Carbon Balance 1950 to 2008: Forest Regrowth on a Massive

Scale

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

Past and current land use change (forest regrowth, woody encroachment

Physiological response (CO2 or

nitrogen deposition

TimeTime

Consequences of Sink Saturation

If the Sink is a Result of:

Sink Strength of US Forests

Sink Strength of US Forests

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.

We are here

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

The Gorilla in the Room:Tropical Deforestation

• 1-2 Petagrams (1015 g)/year – about the same as US fossil fuel emissions

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

• 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.

Further Reading