Managed Forest Contribution to

Carbon Sequestration Under a

Rising Carbon Dioxide Regime

Chris A. Maier

Research Biological Scientist

USFS, Southern Research Station - RWU 4160

Forest Genetics and Ecosystems Productivity

Research Triangle Park, NC

919-549-4072

cmaier@fs.fed.us

2014 Southeastern Regional Forest

Landowner and Manager Conference,

Valdosta, GA

SRS-4160 – Forest Genetics and Ecosystems

Productivity

USDA Forest Service

Research and Developmentwww.fs.fed.us/research

Southern Research Station (SRS)

www.srs.fs.fed.us

Mission: To advance the scientific

understanding of the roles of genetics,

environment, and their interactions to

provide guidelines and tools for

improving the sustainable productivity

of southern forest ecosystems.

Research Focal areas:

Genetics and Genomics

Physiological Processes

Carbon and Nutrient Cycling

*

*

SRS-4160: Research Studies

Forest Productivity and

Resource Availability Forest Response to Elevated

CO2 and soil nutrition

Longleaf Pine (P.

palustris) Restoration

Cold tolerance and water

use in short-rotation

Eucalyptus benthamii

Genotype x Silviculture

‘Cross Carbon Study’

Biomass production for

bioenergy and biofuels

SETRES

Managed forest contribution to carbon

sequestration under a rising atmospheric CO2

• Objectives:

– Forest carbon is a cycle

– Define forest carbon sequestration

– Summarize what is known about how rising CO2

affects tree growth and forest health.

– Carbon management under rising CO2. What can

be done to increase or enhance carbon

sequestration?

Atmospheric CO2 is increasing rapidly

Projected to reach 550 ppm by 2050.

The Carbon Bathtub

Forest and grasslands remove about a third of the additional CO2

Atmospheric CO2 is an environmental paradox

(Beedlow et al. 2004)

– CO2 is a substrate for photosynthesis and essential

for all life

• Photosynthesis increases with increasing CO2

• Plant growth benefits from elevated CO2: “CO2 fertilization effect”

– Greenhouse gas

• Rising atmospheric CO2 and other greenhouse gases (e.g. CH4,

CFCs, and others) will most likely occur in conjunction with cyclical or

linear changes in other climatic factors (temperature and precipitation

regimes.

• Changes in climate will be more severe in some areas

• However, only modest changes in temperature and precipitation are

predicted for most of the southern US through 2050.

Can forest management be optimized to

harness the benefits and mitigate the

problems associated with increases in

atmospheric CO2?

Forest Carbon Sequestration:

the absorption and storage of

carbon from the atmosphere in plant biomass,

detritus, soil, and products

Forest management and carbon

sequestration: Approaches

• No management – carbon reserves in old growth

forests

• Extensive management – long rotations, fewer

extractions, maintain forest structure

• Intensive management – shorter rotations,

frequent extractions, substitute wood for durable

products, and bioenergy

Managing forest for C sequestration is supported by

international scientists and policy makers as a

strategy for mitigating anthropogenic CO2 emissions

“In the long term, a sustainable forest management strategy aimed

at maintaining or increasing forest carbon stocks, while producing an

annual sustained yield of timber, fiber, or energy from the forest, will

generate the largest sustained mitigation benefit.”

4th UN Intergovernmental Panel on Climate Change (IPCC) (2007)

“Increasing both forest stocks and timber harvest will buy time while

we learn more about how trees absorb carbon”

Bellassen and Luyssaert, Nature 2014

Paper

Wood

in situ Pools

ex situ Pools

Atmospheric CO2

Below-ground Biomass(including forest floor)

Above-ground Biomass

Overall Major influences: Land Use

Economics

Major influences: Productivity

Rotation length

Major influences: soil type

management

climate

Major influences: Ownership type

Product classes

Economics

CO2

CO2

CO2

CO2

CO2

CO2

Conceptual model of carbon sequestration via

southern pine forestry

Source: Johnsen et al. JOF 2001

Carbon sequestration

must be understood over

multiple rotationsSource: Maier and Johnsen 2007 GTR-SRS-121

Carbon Storage in a Pine

Plantation

The Forest Carbon Cycle Ecosystem Carbon Pools and Fluxes

• Pools:– Foliage, stems, branches

– Roots

– Litter (above-, below-ground)

– soil

• Processes:– Photosynthesis

– Respiration

– Carbon allocation

– Decomposition

• Variables that regulate carbon fluxes and

storage:– Environment: temperature, precipitation, CO2

– Soil nutrition and hydrology

– Species

– Site history

– Pests and pathogens

From: Landsberg and Gower 1997

Photosynthesis: “CO2 fertilization effect"

• Photosynthesis increases with CO2

• 30-50% at 550 ppm

• Elevated CO2 decreases stomatal conductance

and increases water use efficiency

6CO2 + 6H2O + energy C6H12O6 + 6O2

[CO2] (ppm)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Ne

t P

ho

tos

yn

the

sis

(m

ol m

-2s

-1)

0

10

20

30

40

Pinus taeda

Eucalyptus benthamii

sugar

How sensitive are forests to rising CO2?

• Productivity

• Nutrient supply and demand

• Water use

• Competitive relationships

• Seed production potential

• Pathogens and pest relationships

Will CO2 fertilization increase forest carbon sequestration

under all circumstances and/or alter carbon cycling?

Bio

mass

Present

550 ppm CO2 - Scenario II

550 ppm CO2 - Scenario I

Increase Initial growth rate, carrying capacity, or both?Groninger et al. 1999

Time

current year, Julyambient CO2

amb+200 CO

unfertilized fertilized

As

at(

mo

l m

-2s

-1)

0

2

4

6

8

unfertilized fertilized0.0

0.1

0.2

0.3

0.4

0.5

0.6

An

nu

al S

tem

Gro

wth

(kg

C m

2gr

ou

nd

)

A

E

AE

On this very nutrient poor site:• Elevated CO2 increased photosynthetic rate in

unfertilized and fertilized foliage.

• Elevated CO2 only increased growth when trees were fertilized.

Source: Oren et al. 2001 Nature

Source: Maier et al. 2002 Tree Physiology

SETRES: Elevated CO2A – ambient CO2

E – elevated CO2

AA

E

E

POPFACE : European FACE

Experiment on Poplar Plantations

Oak Ridge (ORNL) CO2 Enrichment

of SweetgumDuke University FACE – Loblolly Pine

Free Air Carbon Enrichment (FACE) Experiments

Norby and Zak 2011

Rhinelander, WI

Tuscania, Italy

Duke Free Air Carbon Enrichment (FACE) Experiments

• Wind carries CO2 into the stand

• Elevated CO2 (ambient +200 ppm CO2).

Duke FACE: Elevated CO2

Sustained increases in biomass

production with CO2

Averaged 28% greater NPP in elevated

treatments

Source: McCarthy et al. 2010 New Phytologist

Source: McCarthy et al. 2010 New Phytologist

Duke FACE: Elevated CO2

Stand growth increased under

elevated CO2, but the extent is

dependent on soil fertility.

Oak Ridge (ORNL) Air Carbon Enrichment (FACE)

Experiments (L. styraciflua)

Elevated CO2

Ambient CO2

Source: Norby et al. 2010 PNAS

• Early large increase in NPP response to CO2

• Increased NPP was not sustained

• Soil N availability declined faster under elevated CO2

Forest Response to Elevated CO2

Source: Norby et al.2005 PNAS; Norby and Zak 2011

NPPa (g C m-2)

500 1000 1500 2000 2500

NP

Pe

(g

C m

-2)

500

1000

1500

2000

2500

Populus tremuloides

P. trem/B. papyrifera

P. alba

P. nigra

P. x euramericana

Pinus taeda

L. styraciflua

Median NPP stimulation of 23±2 %

At high LAI,

enhancement

due to increased

light use

efficiency (i.e.

photosynthesis)

At low LAI,

enhancement due

to increased light

absorption

Will increasing atmospheric CO2 increase carbon

sequestration under all circumstances and/or alter carbon

cycling?B

iom

ass

Present

550 ppm CO2 - Scenario II

550 ppm CO2 - Scenario I

Increase Initial growth rate, carrying capacity, or both?

Groninger et al. 1999

Do forest use less water under

elevated CO2?

• Theory suggests that rising CO2 concentrations

should decrease stomatal conductance and reduce

forest water use.

• Direct effects of elevated CO2 on canopy or stand

water use are more difficult to assess.

• Data indicates that closed-canopy forests reduce

water use 4-11% under elevated CO2

• Response in younger stands is uncertain

Fecundity and Pest

Relationships

• Elevated CO2 increased seed production (Duke), flowering, and

seed mass, germination rate, and seedling vigor (Rhinelander).

• Resin production is important for

defense against bark beetles

• Duke FACE – increased elevated CO2

enhanced resin flow in loblolly pine

• Hypothesis: elevated CO2 increases photosynthesis more than

growth; therefore extra carbohydrate supply will be invested in

reproduction and defensive compoundsSource: Novick et al. 2012 Tree Phys.

Resin

flo

w

Competitive

Relationships

• Species and genotypes express differences in the degree of

response to elevated CO2 that could affect competitive relationships.

• Base on a comparison of 18 FACE experiments, forest ecosystems

appear to be more responsive to CO2 than grassland ecosystems.

• Invasive species?

Source: Nowak et al. 2002

Summary of Elevated CO2 Research

• Rising atmospheric CO2 will likely

increase forest productivity in southern

forests

• The magnitude of this response will be

limited by resource availability

(nitrogen and water)

• Forest may use less water under certain conditions

• Competitive relationships?

• Increased carbohydrate availability under elevated CO2

may impart increased forest resilience:

– Increased production of secondary defensive compounds

– Increased fecundityB

iom

ass

Present

550 ppmCO2 - Scenario II

550 ppm CO2 - Scenario I

Time

Management Implications• Should a forest manager base management decisions based on the certainty of rising CO2

concentrations? Probably not directly.

• Management decisions (e.g. species, genotypes, fertilization, weed control), environmental

variability, and disease will likely have a much larger impact on forest growth than elevated

CO2.

• However, the potential positive effects of CO2 should not be ignored.

– Forest process models suggest potential increases of 20% over the next 30 years from

elevated CO2

– Leverage CO2 fertilization effect through good silviculture

– Increase the efficiency of fertilizer use, primarily nitrogen

– Good weed control

– Maintain soil organic matter

– Utilize genetically improve seedlings (MCP, varietals)

Good Forest Management is Good Carbon Management

Resources

www.fs.usda.gov/ccrc/

www.taccimo.sgcp.ncsu.eduwww.pinemap.org

www.floridaclimateinstitute.org/

www.nc-climate.ncsu.edu/

www.seclimate.org/