Native Plant Productivity and Litter Decomposition in Reclamation of Taconite Iron Ore Tailing

Abstract

Aboveground production and shoot and root litter decomposition rates were measured in amended coarse taconite tailing plots over the second and third growing seasons of a 3-yr study. Plots were seeded with a mixture of native prairie species that included Andropogon gerardii Vitm., Schizachyrium scoparium (Michx.) Nash, Elymus canadensis L., Bromus kalmii Gray, and Lespedeza capitata Michx. Reclamation treatments included inoculation with indigenous mycorrhizal fungi, three rates of fertilizer, and three rates of composted yard waste. Aboveground plant biomass in plots amended with 44.8 Mg ha -1 compost increased from 150 g m -2 in the second season to 330 g m -2 in the third season. The litterbag technique was used to assess the influence of reclamation treatments on the decomposition of plant litter. Shoot litter placed on the surface lost 60 to 70% of its original mass after 15 mo and was unaffected by treatment during the first season but was slower in plots amended with 44.8 Mg ha -1 composted yard waste in the second season. Buried root tissue lost 40% of its original mass after 15 mo and was unaffected by treatment. By significantly increasing plant biomass and reducing litter decomposition rate in tailing, additions of 44.8 Mg ha -1 compost should result in the continued accrual of soil organic matter and begin to meet reclamation goals to establish self-sustaining native plant communities on tailing deposits.