Terrestrial Carbon SequestrationJay AngererTexas AgriLife ResearchBlackland Research and Extension CenterSeptember 3, 2010
OutlineIntroductionGlobal Carbon CyclePlant processesTerrestrial SequestrationForestsCroplandRangelandDisturbed or denuded land
Outline (cont.)Other BenefitsPotential PitfallsMonitoring and MeasurementDecision Support Tools
Where Does Terrestrial Sequestration Fit?From: http://www.netl.doe.gov/technologies/carbon_seq/overview/ways_to_store.html
Terrestrial Carbon SequestrationDefinedFrom Lal et al. (2004):Carbon sequestration implies transferringatmospheric CO2 into long-lived pools andstoring it securely so it is not immediatelyreemitted. Thus, soil C sequestration meansincreasing Soil Organic Carbon (SOC) and Soil Inorganic Carbon (SIC) stocks through judicious land use and recommended management practices (RMPs).
Global Carbon CycleFrom: http://www.netl.doe.gov/technologies/carbon_seq/overview/what_is_CO2.html
Plants as InjectorsFrom: http://www.epa.gov/sequestration/local_scale.html
Local Carbon CycleFrom: http://www.fao.org/es/esa/pesal/role2.htmlPhotosynthesis
Photosynthetic Pathway DifferencesC3 Pathway better able to acquire CO2 with increasing CO2 (fertilizer effect)Rice, barley, wheat, most treesC4 Pathway CO2 is pumped into inner leaf cells to reduce water loss. Does not respond as much to increasing CO2May be beneficial to C sequestration in hot, dry environmentsCorn, tropical grasses From: http://www.geo.arizona.edu/palynology/ geos462/14rockvarnish.html
Pathways of Terrestrial CarbonFrom Lal et al. 2004. Science 304, 1623
Carbon Sequestration: ForestsReforestation replanting areas where trees have been removed Afforestation planting trees in cropland Increasing tree growth increase biomass of tree speciesIncreasing permanence of forest products reduce throw-away tendenciesDecreasing the loss of current forested areas
Carbon Sequestration Rates and Saturation Periods: Forests From: http://www.epa.gov/sequestration/rates.html
Forest Carbon Sequestration ProgramsReforestation of degraded lands with fast growing tree speciesUrban tree plantingFire management of forests and surrounding areasChange other management practices (e.g. logging procedures)
Cropland Carbon SequestrationChanges in crop managementNo-tillMinimum-tillConversion to grasslandManure managementFertilizersIrrigationIncreased use of legumes
Carbon Sequestration Rates and Saturation Periods: Ag LandsFrom: http://www.epa.gov/sequestration/rates.html
Soil Carbon Dynamics In Response To TillageSOIL CARBON (% OF ORIGINIAL) IN RESPONSE TO CULTIVATION1 50 SOIL CARBON0100PlowingPerennial VegetationyearsConservation Tillage50
Factors Affecting SequestrationSoil 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 regions100 to 1000 kg C/ha per year in humid and cool climatesFrom: Lal et al. 2004. Science 304, 1623
Potential LossesSoil ErosionRemoval of residues and mulch can increase erosionDeposition in channels or in aquatic systemsDeposition 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 managementPlowingFertilizer applicationChemical UseThese must be accounted for to get the proper offsetFrom: Lal et al. 2004. Science 304, 1623
Biochar for Improving Ag Soils Fine grained, highly porous charcoalUsed as a soil amendment which improves soil physical and chemical propertiesCan increase site productivityFirst used by Amazonian natives
Rangeland Carbon SequestrationRangelands 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 managementReduced stocking rate or livestock removalGrazing systems
Rangeland Carbon SequestrationImproved resource management Reduce wildfires Reduce water and wind erosionRestore overgrazed and denuded areas
Conversion of cropland to grazingland
Introduce/promote nitrogen fixing legumes
Carbon Sequestration Rates and Saturation Periods: RangelandsFrom: http://www.epa.gov/sequestration/rates.html
Issues with Rangeland Carbon SequestrationLarge 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
Sequestration Potential for Southwest Region
Uncertainty AnalysisUncertainty 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 localesModels need to be calibrated to these conditions
An uncertainty analysis was conducted using carbon modeling results for southwest region
Assessing Uncertainty for Southwest RegionThe 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 LandsIssues affecting carbonExposure of soil Water ErosionWind ErosionCarbon depleted to point where soil amendments may be required
Sequestration on Disturbed LandsDegraded or denuded land offers opportunity to replace/sequester carbonFast growing tree speciesGrasses or grass/legume mixBiochar?
Potential Sequestration RatesFrom: Lal et al. 2004. Science 304, 1623
Other Benefits of Terrestrial SequestrationImproved Ecosystem ServicesCleaner waterCleaner airImproved soil fertilityImproved biodiversity
Potential for monetary benefitsCarbon trading/offsets
PitfallsInteractions with biofuel productionLand areas may be used for biofuel production rather than C sequestration
Implications for food security/livelihoodsIn the case of livestock producers, may reduce land available for grazingIncreasing population may drive land use change to meet food security needs and negate carbon gains
PitfallsLeakage 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 VerificationMonitoringAre (or where) the contracted practices being applied?VerificationAre the contracted practices sequestering carbonEvaluationIs their leakage? Is there proper accounting?ReportingIs the project meeting contract goals?
Monitoring and VerificationGenerally need to sample large area in multiple places to get a reasonable representation of carbon amountsRangelands with non-uniform vegetation and terrain require more samplingSamples using conventional lab analyses are expensive to processTerrestrial sequestration verification would be too expensive to do with conventional methods.
Measurements of Soil CarbonDevelop improved technologies and systems for direct measurements of soil carbon Two MethodsLaser induced breakdown spectroscopy (LIBS)Near Infrared Reflectance Spectroscopy (NIRS)Allow rapid scans of samples in the fieldExamine correlation of results with other technologiesPrinciples for cost effective sampling
Portable NIRS System
Simulation Models and Decision Support ToolsModels 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 ModelsCENTURY ModelModel and Documentationhttp://www.nrel.colostate.edu/projects/century5/Online tool:http://www.cometvr.colostate.edu/
APEX and EPIC Modelhttp://epicapex.brc.tamus.edu/
COLE (Carbon OnLine Estimator): Web-based Tool for Forest Carbon Analysis http://www.ncasi2.org/COLE/
Carbon Decision Support Tool
HomeworkRead 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
For terrestrial sequestration, we are trying to increase that differential between respiration and photosynthesisThe figure above presents a simplified version of the global carbon cycle. The large arrows represent natural paths of carbon exchange, and the small arrows represent the human or anthropogenic contributions to the carbon cycle. The flow of carbon is measured in billions of metric tons (gigatons).
Move the technology from central lab to mobile lab to full fledged portable, real time monitoring system
Leading into our idea to:(next slide)Framework for decision support tool. ArcGIS server as the primary web-map interface. Map interface will allow user to draw boundaries to the land area to be considered for carbon sequestration. Once land area is chosen, the soil boundary/ecological site boundary for the parcel will be shown. User will then choose baseline land management condition or vegetation state (S&T) depending on whether the current landuse is cropland or rangeland. The user will then choose the carbon sequestration practice he/she wants to implement for the entire parcel or for specific soils/land uses. Decision tool will load spatially explicit soil, climate, and other land management data and then run the model for baseline conditions and then under the carbon sequestration practice scenario. Results will then be displayed in tabular format with the option of producing map output showing spatially explicit results.