The relative decomposition potential of habitats variously affected by surface coal mining

Abstract

In a 20-year-old abandoned surface coal mine area in eastern Ohio, fiber glass litter bags containing leaves of Robinia pseudoacacia, Pinits resinosa, and Acer rubrum were set out in three habitats: a non-vegetated strip-mined area, a strip-mined area dominated by Robinia pseudoacacia, and an adjacent unstripped area dominated by Fagus grandifolia and Acer saccharum. From 1 to 6 months after litter fall, there were statistically significant differences in Robinia and Acer leaf litter dry weight between the bare strip-mined habitat and either of the vegetated habitats, both strip-mined and unstripped. After 6 months of decomposition time, rates of decomposition based on dry weight loss became equalized for all litter types in all habitats except for Robinia leaves between the non-vegetated and the vegetated strip-mined habitats. This indicates that changes in decomposition potential because of strip-mining influence the early stages of litter decay. Calculated values for soil pH, texture, organic carbon content, and trace element content indicated that soils from strip-mined habitats contained greater levels of heavy metal cations and were more acidic. Soils from the control area unaffected by mining contained high percentages of sand-sized particles and low concentrations of trace elements, including metals. Soil respiration data measured by manometric techniques in January and April showed significant differences between the strip-mined habitats and the unaffected habitat. In addition, numbers of soil fungi isolated from soil samples of each habitat were higher in the unstrippedcontrol area than in either of the strip-mined areas. Leaf litter decomposition processes appear to be functionally more resistant to environmental impact than is apparent when structural diversity and complexity of soil populations are considered.