Restoration of soil function on coal mine sites in eastern Tennessee 50 years after mining

Services provided by an ecosystem are dependant upon the level at which ecosystem processes function. One potential measure of the success of restoration is to measure the level at which various processes function. We assessed sites in the Cumberland mountains of eastern Tennessee that were mined for coal 40-50 years ago, planted with pine or left to revegetate naturally.  These were compared to adjacent forest that was not disturbed by mining. Field soil respiration rates, tree species composition, basal area and growth rate, root biomass, laboratory microbial soil respiration in root free soil, decomposition rate, soil chemistry and composition of soil macrofauna were measured. Our results suggest that above-ground forest productivity is greater on mined sites than in the un-mined forest, based on tree basal area and on the site index of a common local species, yellow poplar (Liriodendron tulipifera). However tree species composition differs from that of the un-mined area. Areas planted to pine have undergone succession, and pine now comprises less than 10% of the total basal area. Field soil respiration rate in mined areas did not differ between planted and naturally regenerated areas, and both were significantly lower than in the un-mined area.  Field respiration was related to fine root biomass which was highest in un-mined area followed by areas revegetated naturally by hardwood. Soil microbial respiration in root free soil was higher in undisturbed site and pine, and lower in naturally regrowth hardwood. Initial results suggest that recovery of below ground ecosystem processes occurs more slowly than that of above-ground processes.