Sperow, Mark (West Virginia University, Division of Resource Management, P.O. Box 6108, Morgantown, WV, 26506-6108; Phone: 304-293-4832 ext. 4475; Fax: 304-293-3752; Email: Mark.Sperow@mail.wvu.edu)
M. Sperow *, C. Bouquot
Significant progress has been made to estimate the potential for terrestrial systems to mitigate or off-set GHG emissions through carbon (C) sequestration. All potential terrestrial sinks need to be analyzed, particularly those that may be attained with the least cost. Reclaimed mine land sites represent a C sink that could be achieved at a lower cost than other terrestrial C sequestration activities. Few analyses have captured the C sequestration potential from mine reclamation activities. The objective of this study is to analyze potential C sequestration gains in the soil, litter layer, and above-ground biomass on mine land sites in 7 central and northeastern states (IN, KY, MD, MI, OH, PA, and WV) totaling nearly six hundred thousand hectares. Mine operators have been required to reclaim coal mine sites by restoring the original contours of the landscape and planting a vegetative cover since 1977. Over 81% of the land mined since 1992 was in forest and nearly 10% in pasture in 1992. Therefore, while the analysis considers reclaiming mine sites to cropland and grass, the primary focus is on C sequestration under forest and pasture. The C sequestration potential on reclaimed mine sites is analyzed using estimates of the annual rate of C change derived from published journal articles, conference presentations, unpublished studies, and government publications. Existing studies generally do not provide estimates of the carbon stock on mine land soils at the start of reclamation. The IPCC method assumes that “abandoned/degraded” land has lost 50% of soil carbon present under native vegetation, which is the factor used in most of this analysis. In addition, soils in reclaimed mine sites are assumed to be low activity (low clay content) mineral soils due to the disturbance required during mining activities. The 1992 National Land Cover Dataset (NLCD), State Soil Geographic information (STATSGO), and county boundary GIS shape files are combined with specific data for mine lands in each state in the study area to identify and spatially locate surface mine lands. Surface mine permit data in GIS format are only available for Indiana, Kentucky, Ohio, and West Virginia. Mine areas for the remaining states, are derived from the 1992 NLCD. In order to relate surface coal mine permit area with the 1992 NLCD area, only surface mining permits active during and after 1992 are selected for analysis. With the exception of Maryland, these data indicate that the 1992 NLCD and available GIS data underestimate the extent of mine lands in the study region. The analysis shows carbon sequestration is largest by reclaiming all mine land in the study region to forest (1.0 – 2.7 Tg C yr-1) with most C from above-ground biomass (0.7 – 1.1 Tg C yr-1) and soils (0.4 – 1.7 Tg C yr-1). Reclaiming all mine land in the study area to forest provides a biophysical potential of sequestering 21 - 54 Tg C over twenty years. Mine land in West Virginia and Pennsylvania provide the largest C sequestration potential from forest (10.7 and 5.1 Tg C respectively) over twenty years. Reclaiming mine land in Indiana and Ohio to cropland provides 2.2 Tg C over twenty yeas. This is less than the 6.9 Tg C that could be accumulated over twenty years if land is reclaimed to forest.