POTENTIAL ROLE OF ARBUSCULAR MYCORRHIZAL FUNGI IN THE RESTORATION OF AN ABANDONED SURFACE MINE SITE IN WISCONSIN

摘要

Many warm-season prairie grasses are obligately dependent on arbuscular mycorrhizal (AM) fungi for nutrient acquisition, especially in soils low in available phosphorus. An abandoned surface mine in Wisconsin was sampled to assess populations of AM fungi. The site is dominated by the facultatively mycorrhizal cool-season grasses Phalaris arundinacea and Poa pratensis. Repeated attempts to reclaim the site with native warm-season prairie grasses have failed. To test the hypothesis that inoculation with AM fungi would be beneficial to the growth of warm-season grasses, a mixture of Glomus etunicatum and Entrophospora sp. was used to inoculate seedlings of the native prairie grasses Andropogon gerardii and Sorghastrum nutans. Control plants received no inoculum. For both plant species, biomass and root colonization was not different between inoculated and uninoc-ulated plants. Similarly, root colonization did not differ between inoculated and uninoculated plants. At the conclusion of the experiment, all plants were heavily colonized by Glomus intraradices, a fungus present at the field site, suggesting that this native fungus out-competed fungi in the inoculum mixture. These results suggest that factors other than AM fungi are responsible for the limited success in restoration of native grasses. In this instance, field inoculation with AM fungi is not recommended.