Arbuscular mycorrhizae in mine revegetation as affected by fungal source, plant species, and abiotic stress

Arbuscular mycorrhizae (AM) are plant-fungal symbioses that contribute to plant growth through a variety of functions, including enhanced phosphorus uptake. My research examines the role of AM in promoting plant growth in mine waste-contaminated soils. Through a series of greenhouse and field experiments, I examined effects of AM on plant growth while varying the AM fungal source, nonmycorrhizal microbial community, soil abiotic characteristics, and plant species. The AM fungal sources were (1) sterilized inoculum (nonmycorrhizal), (2) inoculum from a metals-contaminated site (possibly adapted to abiotic stress), and (3) inoculum from an uncontaminated site (potentially more diverse and beneficial to plant communities). In most cases, AM from metals-contaminated soils significantly increased plant growth, although effects varied from no difference to a 9-fold increase in biomass. Enhanced biomass in one of the experiments corresponded with phosphorus uptake by plants, but not with tissue metal (Cd, Cu, Fe, Pb, Zn) levels, indicating AM benefits were general mycorrhizal benefits, rather than direct alterations to plant metal-resistance. The microbial amendment (without mycorrhizae) from a metals-contaminated soil eliminated the positive biomass effect seen with the addition of metals-contaminated soil AM fungi. Soil abiotic characteristics were varied in two experiments: a greenhouse experiment including a series of limed tailings treatments, and a field experiment with compost-amended mine wastes. In the greenhouse, AM effects were most pronounced with a low level of lime addition, and in the field, plants growing in compost-amended wastes showed the greatest response to AM fungi. Positive AM effects were much more pronounced for metals-sensitive plant species than metal-resistant species, suggesting that AM inoculation may potentially increase the number of plant species used for revegetation. These experiments show that AM can increase plant success in mine revegetation, but AM effects vary with fungal inoculum source, plant species, and soil abiotic conditions.; In addition to my scientific research, I completed an E.P.A.-sponsored internship focused on incorporating academic research into restoration management strategies. My final chapter summarizes my internship experience, including a discussion of impediments to and strategies for increasing information transfer between academic scientists and restoration managers.