CARBON SEQUESTRATION IN SOILS on REFORESTED COAL MINING SITES IN SOUTHEASTERN KENTUCKY

Soil organic carbon was measured at four locations in Eastern Kentucky in order to assess the impact of surface mine reclamation through reforestation on the soil organic carbon pool. Three surface mines reforested under similar procedures 2, 5, and 14 years ago were sampled, along with soil from an undisturbed forest in the area. Soil was sampled from 4 depths, (0-5, 5-10, 10-25 and 25-50 cm) and samples were analyzed by an isotope ratio mass spectrometer for percent carbon and carbon isotopic signature. The Monte Carlo unmixing equation was used to differentiate geogenic carbon from organic carbon at the mine sites, and coal and litter sample isotopic signatures were used as end-members. Percent carbon was multiplied by the bulk density of soil, one minus the percent rock in the soil, and the maximum depth sampled (50 cm) to obtain the carbon density per unit area at the site. Soil organic carbon content was found to increase with site age. The sequestration rate of the reforested sites is 1.2 Mg C ha^-1 yr^-1, which is comparable to grassland reclaimed sites in the region. Soil organic carbon pools did not recover to levels similar to undisturbed forest soil within 14 years: the 14-year-old site contained 17.2 Mg C ha^-1 while the undisturbed forest contained 78.7 Mg C ha^-1. Additionally, the total terrestrial carbon pool was estimated in the undisturbed forest and compared to regional carbon pool estimates in order to assess how the carbon pool is distributed among soil, living aboveground carbon, coarse woody debris and forest litter. This study quantifies the relative importance of different components of the terrestrial carbon pool, and where there is the largest potential for further carbon sequestration in the forests of Eastern Kentucky surface mined sites. Results suggest that reforestation of mined lands is effective in sequestering soil organic carbon and that the reclaimed sites studied have further potential to uptake CO₂ from the atmosphere.