Can forest management practices enhance carbon storage in Canadian forests?

1
Can forest management practices enhance carbon
storage in Canadian forests? N. Scott1, D.
Layzell2, D. Hollinger3, E. Davidson4, D.B.
Dail5, D. Ray5 1Geography Dept., Queens
University, 2Biology Dept., Queens University,
3USDA-Forest Service, 4The Woods Hole Research
Center, 5University of Maine
CHEMRAWN-XVII and ICCDU-IX, July 11, 2007
2
Can forestry contribute to reducing Canadas CO2
emissions?

• Potential for forestry to help reduce CO2
  emissions
• Case study shelterwood harvest system at
  Howland Forest, Maine

3
Canadas Green Advantage
From David Layzell
National Opportunity and Global Responsibility
4

• 400 Million ha
• 270 M ha (stocked forest productive)
• 130 M ha currently being managed

Stats Canada
Stats canada
5
Stabilization Wedges Modified from National
Round Table on the Environment the Economy
There can be a domestic solution NTREE
2000
Kyoto Commitment Period (2008-12)
1600
Actual Emissions
BAU GHG emissions 1.7/yr
1200
GHG Emissions Mt CO2e/yr
800
Kyoto Target
400
Canadas target if we are to stabilize global CO2
at 2X pre-industrial
0
From David Layzell
2005
2020
2035
2050
1990
Year
Modified from June 2006 Advice on a long term
strategy on Energy Climate Change NRTEE
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What is the potential contribution of forest
management in Canada?

• Existing forest harvest (and regrowth) 250 Mt
  CO2e/yr (70 as roundwood)
• Increase carbon sequestration in forests
  (relative to bau) by 30 to 40 while maintaining
  (or increasing) harvest for wood products or pulp
  paper
• Enhanced carbon storage of 70 Mt CO2e/yr
• BIOENERGY OPTIONS!!

7
Forestry in Canada
http//ecosys.cfl.scf.rncan.gc.ca/disturb/harvesti
ng_e.asp
http//kleercut.net/en/image/tid/32?from0
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Idealized notion of positive management impacts
on forest carbon sequestration
Additional carbon
BAU Biomass Biomass with imp. mgmt BAU
productivity Productivity with imp. mgmt
Biomass (t C/ha)
Productivity (t C/ha/y)
Time (years)
How does structural complexity influence forest
growth and C storage?
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Forest carbon cycle
Mean residence time Where carbon ends up
influences how long it will stay there. Wood
100 y Leaves 1-4 y Mineral soil 10-1000
y Wood products 1-500 y Role of fertilization!
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Disturbance and the Carbon cycle
Disturbance is a key part of the Forest carbon
cycle in Canada
http//www.nrcan.gc.ca/cfs-scf/national/what-quoi/
sof/sof06/InFocus02_e.htmlFigure
Kurz et al. 1993
Thanks to D. Hallett
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Additional carbon benefit of forest
management (floating baseline)
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How forest management alters forest growth and
carbon sequestration

• Change age-class structure
• Change in soil C (e.g. change in CN ratio)
• Replanting
• Fertilization
• Changes in carbon allocation within trees (e.g.
  leaves vs. roots vs. stems)
• Thinning and selective harvesting light
  interception and growth efficiency
• Species composition
• Wood products

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What is needed?

• An integrated system that includes controls to
  establish baseline carbon sequestration rates and
  distinguish between management impacts on carbon
  sequestration and other impacts
• Information on the economic benefits of
  additional C stored to evaluate management
  practices

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Changes in forest management practices in Maine
(1994-1999)
27 of total
Total harvested area in 1999 536,219 acres (6
increase from 1994)
3.5 of total
Maine Forest Service 1999
Shelterwood system 2-3 harvests, 5-15 years
apart, enhances natural conifer regeneration
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Howland Forest control stand

• Commercial spruce-hemlock forest
• GMO Renewable Resources LLC (formerly IP)
• LAI 5.5
• Live tree C 110 Standing dead 10 Down-dead 4
  t C ha-1
• Mineral soil to 1m 100 t C ha-1
• BA43 m2 ha-1
• Age 140 years

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Site age from land use reconstruction

• Near navigable river,
• flat land Colonial use
• Charcoal in soil Site burned
• Soil horizons intact Not plowed, grazed
• Age synchrony Pasture abandoned
• 1860, forest
• age 140
• Old for eastern US!

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Forest Carbon Sequestration

• 2 Approaches to quantifying C sequestration
• Measuring changes in stocks over time
• Direct measurement of fluxes

18
Howland control and experimental eddy covariance
towers (paired tower approach)
Water, energy, carbon dioxide exchange at high
temporal resolution
800m
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Flux data show that forests can switch between
sink source depending on weather

• Mean uptake
• 188 g C m-2 y-1
• High
• variability
• Uncertainty
• 20 g C m-2 y-1

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Shelterwood harvest
Started Nov. 2001 Ended April 2002 Cut to length
and forwarded Removed about 1/3 of basal area
and leaf area
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Carbon pools and harvest C fluxes
Carbon pool Control Harvested (pre-) Harvest C fluxes
Live basal area (m2 ha-1) 43(2.4) 30 (1.7) 22
Live biomass (t C ha-1) 109 (6.6) 77.3 (4.7)
Standing dead (t C ha-1) 10.8 (1.2) 3.3 (0.8)
Down-dead (t C ha-1) 4.1 16.1 (3.9)
Soil 110
Wood removal (t C ha-1) 14.9 (2.1)
AG detritus (t C ha1) 5.3 (1.1)
BG detritus (t C ha-1) 5.2 (0.7)
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Changes in annual increment and net carbon
exchange
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Impact of harvest on carbon uptake
efficiency(growing season)
Whole stand Drops then recovers Per unit
BA Slight drop and then big increase by 3rd year
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Possible mechanisms explaining higher efficiency

• Increase in leaf area (per tree)
• Enhanced N availability and N in foliage
• Physiological changes

• Key change is in water use efficiency

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Forest Vegetation Simulations (FVS)
David Ray, U. Maine
Changes in structure present challenges both for
measurements (e.g. leaf area distribution) and
modeling (stand- and landscape-scale)
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FVS simulations
Basal area
Merchantable volume
Carbon (tons/a)
David Ray, U. Maine
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Future work Stand measurements LA distribution,
more foliar N measurements, coarse root
decay Evaluate other management systems in
Canada based on comprehensive literature
review Remote sensing of forest structure
(sensor fusion) Analysis and adaptation of
forest carbon models to accommodate structural
complexity (e.g. growth and yield models,
WUE) Can we manage for enhanced C sequestration?
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Summary

• Canada has enormous potential to use its
  biological capital to help mitigate rising GHG
  emissions
• With improved management, Canadas forests might
  be able to sequester up to 70 Mt CO2e y-1 with a
  30 enhancement of C stocks
• Shelterwood management systems enhance forest
  growth rates due in part to changes in water-use
  efficiency whether they will store more C
  remains to be seen
• An integrated system that allows for separation
  of management vs. other impacts on forest
  growth is required that can be deployed at a
  range of spatial scales

This research was supported by Office of Science
(BER), US Department of Energy under Interagency
Agreement No. DE-AI02-00ER63028 to the USDA
Forest Service, by Grant No. DE-FG02-00ER63002
to WHRC and DE-FG02-00ER63001 to U. Maine and by
the USDA Forest Service NE Research Station
29
We acknowledge the U.S. Department of Energy
Office of Science and NSERC for support of this
research
Courtesy of Chuck Rodrigues
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6 sprays per season 3 kg/ha N per spray
18 kg N per ha. Load 1 15N as either NO3 or NH4
Courtesy Brian Dail
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Inventory-based measurement of carbon
sequestration (2001 2003)
Control 1.99 Mg C ha -1 y-1 (95
CI0.5) Harvested 1.79 Mg C ha -1 y-1 (95
CI0.5)
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Summary (NAFEW)

• Mature, relatively undisturbed forests at
  Howland, Maine sequester about 1.9 t C ha-1 y-1,
  primarily in bole wood
• Shelterwood harvest removed about 30 of
  biomass, created 10 t C ha-1 detritus, but
  lowered growing-season C uptake after harvest by
  18
• Annual carbon storage in vegetation almost
  recovers to pre-harvest levels 3-4 years after
  harvest
• Recovery of C uptake due in part to a
  post-harvest increase in forest growth efficiency
  (per tree)
• Will C storage in the harvested stand exceed that
  in the control stand??

This research was supported by Office of Science
(BER), US Department of Energy under Interagency
Agreement No. DE-AI02-00ER63028 to the USDA
Forest Service, by Grant No. DE-FG02-00ER63002
to WHRC and DE-FG02-00ER63001 to U. Maine and by
the USDA Foest Service NE Research Station
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Mechanisms behind differences in
efficiency (Physiological changes (water-use
efficiency)
Stand-level changes in WUE
Tree-ring isotope data suggests decline in
WUE What happens with drought?
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How will we achieve these benefits?

• Identify management practices that enhance carbon
  storage
• Fertilization
• Species management
• Selective harvesting
• Thinning
• Manage for different products
• Implement an integrated system that includes
  controls to establish baseline carbon
  sequestration

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Simulated carbon losses following harvest (with
and without wood products)
Measured net uptake for 20040.70 0.25 t C
ha-1y-1
Without harvest 54 Mg C ha-1 (30y) With
harvest, assuming no enhanced uptake 34 Mg C
ha-1 (30y) With harvest, 40 enhancement in net
uptake 54 Mg C ha-1 (30y)
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Recent trends in atmospheric carbon dioxide
concentrations
Keeling and Whorf 2005
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The impact of a harvest on forest C sequestration
depends on several things

• What happens to C uptake loss in the remaining
  forest?
• How does photosynthesis change? Compensation?
• How does soil respiration change? Reduction?
• How much slash is produced how quickly does it
  decay?
• Belowground versus aboveground losses
• How much wood is removed and what is its fate?

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C Storage in US Forests - 1992(Birdsey et al.
1995)

• 298 million ha (lower 48, 246 million ha)
• 54.6 Gt C (lower 48, 38.6 Gt)
• Sequestration
• 0.29 Gt y-1
• US emissions 1.6
• Mostly due to
• forest regrowth

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Future C Storage in US Forests (Birdsey et al.
1995)

• Predicted US Forest C sequestration expected to
  decrease
• Cause is aging
• forests age
• related decline
• in productivity

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• Reconstructed diameters indicate a mean tree
  sink of 164 g C m-2 y-1
• Uptake decreas-ing by 1 g m-2 y-1

• Tree C sink not correlated with variations in
  tower flux, but consistent with tower data

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Carbon consequences of forest management
How quickly does forest growth recover?
Wood products
Paper products
Sawdust
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Fate of harvested wood Wood products produced,
and their longevity, affects the net C balance
of the shelterwood harvest regime
Product Wet mass (tons) total Half-life (y)
Boltwood 232 2 20
Chipwood 364 3 3.5
Groundwood 199 2 3.5
Logs 4771 40 45
Pulp 4265 36 3.5
Studs 463 4 45
Tree length 1511 13 3.5
Skog and Nicholson 1998