Terrestrial Carbon Sequestration
Jay Angerer
Texas AgriLife Research
Blackland Research and Extension Center
September 3, 2010
Outline




Introduction
Global Carbon Cycle
Plant processes
Terrestrial Sequestration
Forests
 Cropland
 Rangeland
 Disturbed or denuded land

Outline (cont.)




Other Benefits
Potential Pitfalls
Monitoring and Measurement
Decision Support Tools
Where Does Terrestrial Sequestration Fit?
From: http://www.netl.doe.gov/technologies/carbon_seq/overview/ways_to_store.html
Terrestrial Carbon Sequestration
Defined

From Lal et al. (2004):
“Carbon sequestration implies transferring
atmospheric CO2 into long-lived pools and
storing it securely so it is not immediately
reemitted. Thus, soil C sequestration means
increasing Soil Organic Carbon (SOC) and Soil
Inorganic Carbon (SIC) stocks through judicious
land use and recommended management
practices (RMPs).”
Global Carbon Cycle
From: http://www.netl.doe.gov/technologies/carbon_seq/overview/what_is_CO2.html
Plants as “Injectors”
From: http://www.epa.gov/sequestration/local_scale.html
Local Carbon Cycle
Photosynthesis
Photosynthetic Pathway
Differences

C3 Pathway – better able
to acquire CO2 with
increasing CO2 (fertilizer
effect)


C4 Pathway – CO2 is
“pumped” into inner leaf
cells to reduce water loss.



From: http://www.geo.arizona.edu/palynology/
geos462/14rockvarnish.html
Rice, barley, wheat, most
trees
Does not respond as much
to increasing CO2
May be beneficial to C
sequestration in hot, dry
environments
Corn, tropical grasses
Pathways of Terrestrial Carbon
From Lal et al. 2004. Science 304, 1623
Carbon Sequestration: Forests





Reforestation – replanting areas where
trees have been removed
Afforestation – planting trees in cropland
Increasing tree growth – increase
biomass of tree species
Increasing permanence of forest products
– reduce “throw-away” tendencies
Decreasing the loss of current forested
areas
Carbon Sequestration Rates and
Saturation Periods: Forests
From: http://www.epa.gov/sequestration/rates.html
Forest Carbon Sequestration
Programs




Reforestation of degraded lands with fast
growing tree species
Urban tree planting
Fire management of forests and
surrounding areas
Change other management practices (e.g.
logging procedures)
Cropland Carbon Sequestration

Changes in crop management
No-till
 Minimum-till
 Conversion to grassland
 Manure management
 Fertilizers
 Irrigation
 Increased use of legumes

Carbon Sequestration Rates and
Saturation Periods: Ag Lands
From: http://www.epa.gov/sequestration/rates.html
Soil Carbon Dynamics In
Response To Tillage
SOIL CARBON (% OF ORIGINIAL) IN RESPONSE TO CULTIVATION
100
Perennial
Vegetation
Conservation
Tillage
Plowing
50
0
1
years
50
Factors Affecting Sequestration




Soil texture (sand, silt, clay percentages)
Soil profile characteristics (depth, rocks)
Climate (temperature, humidity, rainfall)
Rates can range from:
0 to 150 kg C/ha per year in dry and warm
regions
 100 to 1000 kg C/ha per year in humid and
cool climates

From: Lal et al. 2004. Science 304, 1623
Potential Losses

Soil Erosion


Removal of residues and mulch can increase erosion
Deposition in channels or in aquatic systems



Deposition is 0.4 to 0.6 Gt C/year
0.8 to 1.2 Gt C/year is lost to exposure to atmosphere
Must assess carbon used for crop management




Plowing
Fertilizer application
Chemical Use
These must be accounted for to get the proper offset
From: Lal et al. 2004. Science 304, 1623
Biochar for Improving Ag Soils




Fine grained, highly
porous charcoal
Used as a soil
amendment which
improves soil physical
and chemical
properties
Can increase site
productivity
First used by
Amazonian natives
Rangeland Carbon Sequestration

Rangelands are generally characterized as
grasslands or shrublands that are not suitable
for consistent crop production

Occupy almost 50% of worldwide land area

Carbon sequestration would require changes in
grazing management


Reduced stocking rate or livestock removal
Grazing systems
Rangeland Carbon Sequestration
Improved resource
management



Reduce wildfires
Reduce water and wind
erosion
Restore overgrazed and
denuded areas

Conversion of cropland to
grazingland

Introduce/promote
nitrogen fixing legumes
Carbon Sequestration Rates and
Saturation Periods: Rangelands
From: http://www.epa.gov/sequestration/rates.html
Issues with Rangeland Carbon
Sequestration

Large land area, but relatively low carbon storage

In US, most rangelands are privately owned or are public
lands (e.g. BLM land)

High degree of uncertainty in sequestration estimates for
most regions

Need large land areas to be attractive to potential buyer
or as an offset

May require development of government programs for
assisting farmers/ranchers in joining carbon
sequestration programs
Assessing Carbon Sequestration
Potential for Programs
GIS Phase
Precipitation
Classification
COMET VR
Phase
Carbon Sequestration
Potential
Classification
Land Tenure Status
Soil Organic Carbon
Classification
Wind Erosion/Calcium
Carbonate
Classification
Major Land Resource
Area Designation
Land Cover
Assessment within
Carbon
Sequestration
Potential Classes
Target Areas for
Programs/
Interventions
Defined
Define USDA Program
Available for
Sequestration
(e.g. CRP)
Conduct COMET VR
Simulations for Base and
Program Scenarios
Assess Potential
for Carbon
Sequestration
under Regional
Program
Sequestration Potential for
Southwest Region
Uncertainty Analysis

Uncertainty in prediction of carbon
sequestration on agricultural lands can be high,
especially on rangelands



Lack of quantitative information on carbon
sequestration for various practices and locales
Models need to be calibrated to these conditions
An uncertainty analysis was conducted using
carbon modeling results for southwest region
Assessing Uncertainty for
Southwest Region

The estimated amount of carbon
sequestered and its associated uncertainty
were mapped

A weighted averaging procedure was used
based on soil texture, soil map unit, major land
resource area, and county.

Spatially explicit maps of the carbon
sequestered and uncertainty were produced
Sequestration on Disturbed
Lands

Issues affecting
carbon
Exposure of soil
 Water Erosion
 Wind Erosion
 Carbon depleted to
point where soil
amendments may be
required

Sequestration on Disturbed
Lands

Degraded or denuded land offers
opportunity to replace/sequester carbon
Fast growing tree species
 Grasses or grass/legume mix
 Biochar?

Potential Sequestration Rates
From: Lal et al.
2004. Science
304, 1623
Other Benefits of Terrestrial
Sequestration

Improved Ecosystem Services
Cleaner water
 Cleaner air
 Improved soil fertility
 Improved biodiversity


Potential for monetary benefits

Carbon trading/offsets
Pitfalls

Interactions with biofuel production


Land areas may be used for biofuel production
rather than C sequestration
Implications for food security/livelihoods
In the case of livestock producers, may reduce
land available for grazing
 Increasing population may drive land use
change to meet food security needs and negate
carbon gains

Pitfalls

Leakage

The IPCC Special Report (2000) defines
leakage as "the unanticipated decrease or
increase in greenhouse gas (GHG) benefits
outside of the project's accounting boundary as
a result of project activities."

Example: For a forest under a C sequestration
program, logging may be displaced to an area
outside the Project area. The CO2 emissions
that result from the displaced logging could
partially or completely negate the benefits of
avoiding CO2 emissions in the protected forest.
Monitoring and Verification

Monitoring


Verification


Are the contracted practices sequestering
carbon
Evaluation


Are (or where) the contracted practices being
applied?
Is their leakage? Is there proper accounting?
Reporting

Is the project meeting contract goals?
Monitoring and Verification

Generally need to sample large area in
multiple places to get a reasonable
representation of carbon amounts
Rangelands with non-uniform vegetation and
terrain require more sampling
 Samples using conventional lab analyses are
expensive to process
 Terrestrial sequestration verification would be
too expensive to do with conventional
methods.

Measurements
of Soil Carbon

Develop improved technologies and
systems for direct measurements of soil
carbon

Two Methods
Laser induced breakdown spectroscopy (LIBS)
 Near Infrared Reflectance Spectroscopy (NIRS)
 Allow rapid scans of samples in the field

Examine correlation of results with other
technologies
 Principles for cost effective sampling

LIBS System
Portable NIRS System
Simulation Models and Decision
Support Tools

Models can be used to assess carbon
sequestration potential for a given area

Provide the ability to examine different
management alternatives for carbon gain

Allow examination of other outputs such
as erosion and water quality under the
selected practice
Simulation Models

CENTURY Model

Model and Documentation
http://www.nrel.colostate.edu/projects/century5/


APEX and EPIC Model


Online tool:
http://www.cometvr.colostate.edu/
http://epicapex.brc.tamus.edu/
COLE (Carbon OnLine Estimator): Web-based
Tool for Forest Carbon Analysis

http://www.ncasi2.org/COLE/
Carbon Decision Support Tool
Map Driven User Interface
Carbon Practice Selection
(State and Transition [S&T] interface)
Climate
Data
Carbon
Sampling
Decision Support
Engine (Comet-VR,
Carbon Potential
Assessment, Spatial
Queries, etc.
S&T
Data
Remote
Sensing
Data
Soils
Data
Other Ag
Data
Web Soil
Survey
Map Output
Report
Output
Homework

Read two journal articles:

Soil Carbon Sequestration Impacts on
Global Climate Change and Food Security
R. Lal (11 June 2004) Science 304 (5677), 1623.

Soil carbon sequestration to mitigate climate
change and advance food security.
R. Lal, et al. Soil Sci 172 no12 D 2007
Questions?