Southeast Regional Carbon Sequestration Partnership (SECARB) Volume II

Terrestrial carbon sequestration options are defined as land-resource management actions that have the potential to increase carbon storage, relative to a baseline of unchanging management. This study assesses the potential for terrestrial carbon sequestration options to offset carbon emissions from energy production within the state of Virginia. Using a Geographic Information System (GIS) approach, three options were evaluated by applying two modeling methods. The terrestrial carbon sequestration options evaluated are conversion of marginal agricultural land to long-term forest cover, conversion of tillage practices for row crops, and afforestation of agricultural lands within riparian zones and farmed wetlands; each was evaluated on a statewide basis and within each of the state's 7 Level III ecoregions. Modeling methods applied were the ?Winrock method,? which was intended to develop estimates from a basis comparable to that applied by Winrock International over other portions of the SECARB region, and alternative methods developed at Virginia Tech (?VT method?) which consider additional factors and local conditions. Publicly available data were gathered to develop a spatial database of relevant variables, and that database was manipulated through a variety of GIS analytical techniques to estimate the carbon sequestration for each option. Because the VT methods are based on a more detailed analysis, conclusions regarding the options? carbon sequestration potentials are drawn from the VT method's application. Of the options valuated, afforestation of marginal agricultural lands was found to have the highest carbon sequestration potential (1.4 Tg C yr-1, on average, over the first 20 years if applied on all eligible lands). The areas with greatest opportunity for application of this option are the Ridge and Valley ecoregion of western Virginia (steep, shallow soils) and in the Tidewater area in eastern Virginia (wet soils). Sequestration potential estimates for the afforestation options are for biomass carbon only and do not consider soil carbon, but other investigators? findings indicate a likelihood that consideration of soil carbon changes would increase the estimated carbon sequestration potentials of these options. The analysis indicates that widespread implementation of this option within the near-term would be capable of offsetting about 3 percent of annual energy-related CO2 emissions, on average, over the following 20 years, with sequestration continuing but at declining rates beyond that initial 20-year time frame. Considering societal effects as well as estimated C sequestration rates, we consider the most promising option to be afforestation of marginal agricultural lands in combination with afforestation of selected riparian agricultural lands and management enhancements on residual agricultural lands. The sequestration potential estimates developed through this research are general estimates and do not include carbon losses or gains associated with harvested products, management activities, or any other source/sink of carbon. The estimates presented here are best regarded as potentials that serve as starting points for regional planning projects.

Tags: kmd