Using GIS to Assess Virginia ’ s Best Options for Sequestering Carbon through Land-Use Management Jeffrey Galang 1, Carl Zipper 1, Stephen Prisley 2, John Galbraith 1 and Randolph Wynne 2 Virginia Tech Department of Crop and Soil Environmental Sciences 1 Virginia Tech Department of Forestry 2

Objectives  Identify the most promising terrestrial carbon sequestration options for Virginia Carbon sequestration rates per ecoregionCarbon sequestration rates per ecoregion Statewide totalsStatewide totals  Develop a statewide database of relevant spatial information Elevation (30m), National Land Cover Data (1992), State Soil Geographic Data, conservation tillage data (NASS/CTIC), National Hydrography Data (med. resolution), and boundaries (county and ecoregion)Elevation (30m), National Land Cover Data (1992), State Soil Geographic Data, conservation tillage data (NASS/CTIC), National Hydrography Data (med. resolution), and boundaries (county and ecoregion)  Assess the regional carbon sequestration potential for three land-use changes Option A: Afforestation of marginal agricultural landsOption A: Afforestation of marginal agricultural lands Option B: Conversion of conventional tillage (CT) crops to no-till (NT) cropsOption B: Conversion of conventional tillage (CT) crops to no-till (NT) crops Option C: Afforestation of agricultural lands within riparian areasOption C: Afforestation of agricultural lands within riparian areas

Level III Ecoregions of Virginia

Methods (Option A – Marginal Lands’ Afforestation )  Identify marginal lands for agriculture: Productivity limitations (e.g. flooding, hydric, rocky, droughty, etc.)Productivity limitations (e.g. flooding, hydric, rocky, droughty, etc.) Highly erodible (Erodibility Index ≥ 8)Highly erodible (Erodibility Index ≥ 8) Steep gradients (frequency distribution, >95%)Steep gradients (frequency distribution, >95%)  Overlay with map of agricultural lands (pasture/hay and row crops)  Obtain C sequestration potentials (20, 40, and 80 years) from STATSGO WOODPROD and empirical yield tables (McClure and Knight, 1984; Brown and Schroeder, 1999)  Overlay C sequest. potentials with marginal ag. lands  Calculate total carbon sequestered by ecoregion

Methods (Option B – Conservation Tillage )  Calculate area (m 2 ) of each county in wheat, soybean, and corn production (NASS)  Adjust to reflect percent of county in conventional tillage (CTIC)  Generalize texture class of each STATSGO map unit (fine, medium, coarse) and apply carbon sequestration potentials (West and Post, 2002)  Overlay with locations of row crops Calculate total C sequest. by ecoregion  Calculate total C sequest. by ecoregion

Methods (Option C – Riparian Ag. Afforestation )  55’ buffer around all medium resolution NHD streams and waterbodies (including hydric soils / wetlands)  Overlay with pasture/hay and row crop locations  Apply the same carbon potentials derived for Option A  Calculate total carbon within each ecoregion

Modeling Results: Total C Sequestration Potential Note: Ecoregions ordered West to East 1.42 Tg yr Tg yr Tg yr -1

Modeling Results: C Sequestration Potential per Hectare Note: Ecoregions ordered West to East

Results – Option A

Results – Option B

Results – All Options 1.62 Tg C yr -1

Agricultural Land (Cropland + Pasture) Defined as “Marginal” Using Three Criteria 16% of state agricultural land base affected by Option A

Significance of modeled terrestrial C sequestration potential for Virginia, relative to Year 2010 emissions measures * Expressed as C, from fossil fuel combustion projected using DOE data.

Conclusions  Provides a valuable tool for planning regional projects.  The afforestation of marginal agricultural lands (Option A) has the highest maximum potential for carbon sequestration (≈5% of state CO 2 emissions)  MACP and R&V have the highest potential rates of sequestration

Questions?