INTERACTIONS BETWEEN NATIVE PRAIRIE GRASSES AND INDIGENOUS ARBUSCULARMYCORRHIZAL FUNGI - IMPLICATIONS FOR RECLAMATION OF TACONITE IRON-ORETAILING

In a glasshouse experiment using coarse taconite iron ore tailing as t he substrate, we examined interactions between the warm-season grasses Andropogon gerardii (big bluestem) and Schizachyrium scoparium (littl e bluestem), and the cool-season grass Elymus canadensis (Canada wild rye), and indigenous arbuscular mycorrhizal (AM) fungi from an adjacen t fine tailing basin. Shoot dry mass (DM), P uptake, shoot P concentra tion, root DM, root length, spore density, percentage root length colo nized, and length of external AM fungal hyphae were measured over a gr adient of phosphate availability. Andropogon gesardii was highly depen dent and responsive to inoculation at low P, whereas inoculation had n o significant effect on the growth of S. scoparium. Root DM and root l engths of both warm-season grasses were unaffected by mycorrhizal inoc ulation. Elymus canadensis was responsive only at the lowest P level a nd not dependent on mycorrhizas; in fact, shoot DM, P uptake, root DM and root lengths were all greater in control than inoculated plants at moderate P levels. Despite a growth suppression, colonized root lengt hs for E. canadensis were approximately five times longer than warm-se ason grasses at low P levels, making it suitable as an early successio n species for increasing mycorrhizal inoculum potential and thus enhan cing the successful reclamation of coarse tailing deposits by more per sistent, mycorrhizal-dependent species.