Southwest Carbon Sequestration

Analyses conducted as part of the Southwest Carbon Sequestration Project - Phase I on terrestrial carbon sequestration potential for the Southwest region clearly showed that there is tremendous potential to increase carbon storage in soils and vegetation through changes in land use and management.

Achieving that potential, however, is constrained by three factors:

  • Low per ha rates of accumulation due to low rainfall and soil fertility
  • Year to year climatic variability that makes local prediction of sequestration  difficult
  • Lack of cost effective carbon measurement systems.

The greatest influence on carbon stocks in the area, without doubt, is yearly variation in precipitation. However, changes in land use and management also greatly influence soil and vegetation carbon fluxes. Broad, landscape scale analysis showed that much of the region would be predicted to accumulate soil carbon at less than 0.1 t/ha/y unless changes in land use occurred, primarily converting cropland to perennial grasses or trees. Land use conversion can result in accumulation rates of up to 1.0 t/ha/y in a limited portion of the region. Given current economic constraints on the ability of land managers to change land use, the potential for conversion is limited.

Southwest Carbon Map

The dominant influence on land use and management in the region is government policy. The impact of federal conservation programs on private land management is prevalent throughout the region. Government programs such as the Conservation Reserve Program (CRP) encourage land conversion from cropland to perennial plant cover and other programs such as the Conservation Security Program (CSP), Environmental Quality Incentives Program (EQIP), Wildlife Habitat Incentives Program (WHIP), etc., provide incentives for land managers to adopt conservation practices on cropland, rangeland and forestland. It is through these land use changes and adoption of management practices that the greatest increases in terrestrial carbon storage will occur.

Crediting changes in terrestrial carbon and assigning them to specific management requires a system of monitoring, measurement and verification that can reliably separate changes in climatically driven fluxes from those due to actions taken by land managers.  The ability to partition changes in carbon stocks is greatly limited by the climatic and edaphic constraints described above.

Objectives

To overcome the constraints described above, we will develop a carbon reporting and monitoring system that functions consistently across hierarchical scales and is compatible with the existing technology underlying the 1605b reporting system.  Our major objectives in developing and implementing this system are as follows:

  • Develop improved technologies and systems for direct measurements of soil and vegetation carbon at reference sites selected within Southwest Carbon Partnership region
  • Develop remote sensing and classification protocols to improve mesocsale (km2) soil and vegetation carbon estimates
  • Construct ecological process (State and Transition) models that reflect soil/vegetation changes resulting from current land use and land use associated with implementation of programs to sequester carbon or reduce carbon losses
  • Develop a regional inventory and decision support tool that integrates information gathered during the course of the Phase I investigation and from Objective 1-3 above

Field NIRS

Regional Terrestrial Pilot Tasks

Task 1: Surface Carbon Measurements

Objective: Develop improved technologies and systems for direct measurements of soil and vegetation carbon at reference sites selected within Southwest Carbon Partnership region (Principal Investigator, Dr. Joel Brown, ARS in collaboration with Dr. Mike Ebbinger of Los Alamos National Laboratory and Jay Angerer of Texas A&M University).

The purpose of Objective 1 is to use advanced instrumentation on the ground to identify and characterize the distribution of soil carbon, then to relate these distributions to the land use practices implemented at the site. Advanced techniques for measuring soil carbon and other nutrients are needed. We will address three tasks for Objective 1:

Subtasks:
1.1 Calibrate and test the newly developed Laser-Induced Breakdown Spectroscopy (LIBS) instrument along with portable Near Infrared Spectroscopy (NIRS) for soil carbon measurements.
1.2 Determine near land surface patterns of soil carbon in a spatially extensive manner.
1.3 Relate near land surface patterns of soil carbon to associated soil profiles, site inventories, and management practices

Task 2 - Remote Sensing Classification Protocols

Objective: Develop remote sensing and classification protocols to improve mesocsale (km2) soil and vegetation carbon estimates (Principal Investigator: Dr. Kris Havstad, USDA ARS)

The purpose of this objective is to identify and refine existing techniques in remote sensing that can detect and link changes in vegetation and soil properties that reflect soil C at a scale consistent with the output from Objective 1. While remotely sensed imagery has been valuable in natural resource management as a tool for inventory and large-scale production estimation, there has been little, if any, application to site-specific management such as land use and management change related to carbon sequestration.

Subtasks:
2.1.  Using results of the spatial characterization of carbon at the selected study sites in Objective 1, determine remote sensing technology(ies) capable of providing appropriate scale and frequency of imagery that could be useful in assessing changes in carbon stocks.
2.2.  Integration of remote sensing data identified in Task 1 above into the state and transition models and regional inventory and decision support tool (Objective 4).

Task 3 - Ecological Process Models

Objective: Construct ecological process (State and Transition) models that reflect  soil/vegetation changes resulting from current land use and land use associated with implementation of programs to sequester carbon or reduce carbon losses (Principal Investigator: Dr. Joel Brown, ARS).

The purpose of this objective is to integrate existing qualitative knowledge about soil/vegetation change in response to management and climate variability and quantitative information gained as a result of Objective 1 into State and Transition Models (STMs) appropriate for the regions represented by our study sites, link to objective remotely sensed land attributes (Objective 2) and provide inputs to improve model estimates (Objective 4).

Subtasks:
3.2 Develop State and Transition Models (STMs) for the range of soil/vegetation combinations represented by the carbon management practices and land uses in the selected study areas.
3.3 Distribute STMs across appropriate soil units within the region.
3.4 Integrate the STMs into the regional inventory and decision support system.

Task 4 - Regional Carbon Inventory

Objective: Develop a regional inventory and decision support tool that integrates information gathered during the course of the Phase I investigation and from Objective 1-3 above. (Principal Investigator: Jay Angerer, Texas A&M University)

The purpose of this objective is the development of a tool that will allow the integration of the spatial and carbon sequestration potential data developed under Phase I of this partnership along with the information and data gathered as part of Tasks 1, 2, and 3 of this effort into a decision support framework that can be used by landholders, service agencies (NRCS), and policy makers. This tool would allow a spatially explicit analysis of carbon sequestration at local scales and allow aggregation of sequestration response under various conditions to regional scales.

Subtasks:
4.1 Build a web-based tool, with a GIS framework, that incorporates the soil, climate, and land use data gathered and processed in Phase I along with the soil carbon, state and transition, and remote sensing data gathered in the Phase II efforts.
4.2 Establish a linkage to the COMET VR tool that will allow the data fields required by COMET VR to automatically filled based on the latitude/longitude, premise boundary, or region input or selected by the user.
4.3 Build a State and Transition Interface that will allow users to examine carbon sequestration under various management practices, government programs, or land uses.
4.4 Design display tools for mapping, data visualization, and reporting in a spatially coherent manner.
4.5 Improve the COMET VR tool for assessing carbon sequestration at the individual field and farm scale for arid and semi-arid rangelands and croplands.
4.6 Develop protocols for updating the system with new data (NASS, NRI) and options for carbon sequestration so that the system will current with relevant government programs and incentives.