Estimating the potential carbon supply from changes in land use: afforestation of grazing lands in the US as a case study

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Third USDA Symposium on Greenhouse Gases C
Sequestration in Agriculture and
Forestry Baltimore, March 2005

• Estimating the potential carbon supply from
  changes in land use afforestation of grazing
  lands in the US as a case study

Sandra Brown Winrock International sbrown_at_winrock.
org
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A key question ..

• What amount of carbon is available and where from
  changing land use and management practices at
  what price?
• Goes beyond just technical potentialalso
  includes economic potential

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Acknowledgements
Winrock Team Timothy Pearson David Shoch Brent
Sohngen John Kadyszewski Jonathan
Winsten California Dept. Forestry Mark
Rosenberg Doug Wickizer Support American Electric
Power Ogelthorpe CA Energy Commission/PIER Electri
c Power Research Institute US DOE
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Overall Methodology

• Identify and locate land classes suitable for
  increasing carbon stocks
• Estimate rates of carbon accumulation for each
  major potential class of project activity for
  each land class
• Assign costs to each contributing cost factor
• Estimate carbon supply

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Regional analyses of carbon supply

• California-WESTCARB partnership
• Southern region-SSEB partnership

Details of analyses are in reports
at www.winrock.org/what/ecosystem_pubs.cfm
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California-WESTCARB Afforestation of rangelands
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Identify and locate land suitable for increasing
carbon stocks

• Determine which rangelands could support
  forestssuitability analysis
• Land-use suitability analysis based on
• Biophysical factor-dependent suitability for
  forest habitats

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Identify rangelands suitable for conversion to
forests

• Analyze the relationship between existing forests
  and several biophysical factors using GEOMOD
  suitability for forest map
• Cross-reference suitability map to areas of
  current rangelands to select areas with
  afforestation potential.
• Product map of rangeland areas suitable to
  support forests

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Prepare factor maps
Inputs to GEOMOD Converted to forest probability
maps based on existing extent in each class
Slope
Mean annual temperature
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Area of existing rangelands suitable for forest
growth
Montane chaparral
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Map of populated places, montane chaparral areas,
and selected populated places with names that
refer to forests or forestrye.g. Pine Grove,
Pine Valley, Pinehurst, Redwoods, Sequoia, Seven
Oaks, Sherwood Forest, Stallion Oaks, Sugarpine,
Tall Timber Camp
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• Map of rangeland areas (in yellow) suitable for
  afforestation
• Represent about 9.3 million ha or 23 of State
  area

Areas where forest crown cover high, suggesting
not suitable
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Afforestation of grazing lands-Estimate rates
of C accumulation and costs
Step 1
Step 2
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Step 1

• Generate carbon sequestration curves from
  establishing forests on grazing lands from
  integration of many data bases

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Potential carbon accumulation in conifer and
hardwood forests (no harvest)
Select species for afforestation based on
incidence of existing forests with same
suitability score/bioregion
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Net carbon accumulation applied to potential
woody-species distributions over three time
periods
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Step 2

• Economic analyses

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Cost of carbon sequestration

• Opportunity costs
• Using the same biophysical factors, a
  multivariate model was used to extrapolate
  STATSGO forage productivity data samples to a
  state-wide coverage.
• Product map forage production
• Economic analysis of forage value derived from
  national databases and field interviews
• Mean annual profit/cow (68/cow)
• Number of cows supported based strongly on
  forage production (1 animal unit month for CA
  791 lbs)
• Net present value analysis of total costs using
  4 discount rate
• Product map total cost

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Estimated forage productivity across rangeland
classes
lbs per acre per year
This map used to estimate number of cows per acre
based on AUM and opportunity cost based on
profitability per cow
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• Combine quantities of carbon accumulation with
  cost data to generate C supply in /t C

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Cost of carbon sequestration through
afforestation of California rangelands
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Carbon supply curves for afforestation activities
for 20, 40 and 80 years
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Take home messages

• Depending on the price, afforestation of grazing
  lands can provide substantial quantity of carbon
  offsets in the US
• Little to no new technology needed, can be
  adopted quickly, and provide other environmental
  benefits
• Protocols and registries for implementing carbon
  sequestration activities in advanced state (e.g.
  CCAR) and markets developing
• Incentive for adoption likely to be driven by
  states rather than feds