Redevelopment of Soil Carbon Pools on Reclaimed Surface Mine Lands

Soils play a crucial role in the global carbon cycle; they represent a carbon reservoir larger than the atmosphere, they are the site of a number of key carbon transformations (e.g. mineralization and humification), and contain a number of unique carbon pools (e.g. plant litter, humic substances, dissolved organic matter, etc.). Land disturbance associated with surface coal mining results in complete disruption of the soil system, loss of a significant portion of soil carbon content, and disturbance of many of the organisms that play critical roles in the carbon cycle (primary producers and decomposers). One of the challenges of surface mine reclamation is reconstruction of a soil system which functions properly in the impacted ecosystem. The objective of this paper is to report our research findings on the recovery of soil carbon pools in reclaimed surface mined lands. Data from our studies indicate 2 mechanisms are important in the rapid accumulation of C from plant litter into soil: physical protection by soil aggregates and biochemical protection of high lignin content. Examination of chronosequences of reclaimed soils indicates plant litter is rapidly incorporated into soil aggregate structure in most of these soils. Lignin content of reclaimed soils we analyzed were higher than that of nearby undisturbed soils, indicating the recalcitrant nature of soil C in reclaimed soils and/or possibly the slow recovery of lignin degrading organisms, primarily fungi. Assays of potentially mineralizable C indicate concentrations of labile C in reclaimed soils reach amounts similar to those in undisturbed soil within 5 or 6 years after revegetation. Additional