Amichev, Beyhan (Virginia Tech , Blacksburg, VA228, Cheatham Hall (0324), Department of Forestry, Blacksburg, VA, 24061; Phone: 540-231-6958; Email: bamichev@vt.edu)

 

Forest Soil Carbon Spatial Variation and Precision Accounting on Mined Land

 

B.Y. Amichev*, J.A. Burger

 

Carbon accreditation of forest development projects is an essential approach to sequestering atmospheric C under the provisions of the Kyoto Protocol. Standard soil C accounting methods tend to largely overestimate the C contained in soil-incorporated organic matter on mined lands. This study was conducted (i) to determine the distribution pattern and variation of soil C stock down the soil profile and across space and (ii) to compare two methods of precision soil C accounting on mined land. We measured the soil C content on 9 mined sites reclaimed to pastureland in the period after the passage of Surface Mining Control and Reclamation Act of 1977 (SMCRA). Mine soil samples of the surface soil layer (topsoil) and the subsurface overburden material (mine spoil) were collected; chemical and physical soil properties were determined on the less-than-2mm fine sample fraction. Soil C stock maps were generated using common geostatistical procedures in ArcGIS 8.2 software. Our results show that the soil C variation across space was greater in the mine spoil (CV of 35% to 81%) compared to the topsoil (CV of 31% to 53%). Bulk density of the fine fraction (BD), C:N ratio (CN), coarse fragment content (CFC) and electrical conductivity (EC) explained between 54% and 91% of the variation of mine spoil C stock. Percent sandstone (SS), CN, and BD explained between 33% and 92% of the variation of topsoil C stock. The mean soil C stock computed as the average of collected soil samples was greater than that derived from the soil C stock maps. On average the C content decreased 30% for every 10 cm down the mine soil profile. There was no evident pattern in the vertical distribution of soil C most likely due to irregular alterations of soil properties down the soil profile during the many years of mine spoil weathering.