Soil Inoculation with Arbuscular Mycorrhizal Fungi Promotes the Growth of Boreal Plant Communities in Gold Mine Overburden

The importance of mycorrhizal partnerships to plant health is well documented. Mycorrhizae are considered drivers of ecosystem processes in boreal forests, which represent some of the most taxon rich arbuscular mycorrhizal fungi (AM) habitats in the world. Methods of inoculating gold mine overburden with AM were evaluated in this study during a 17-week greenhouse trial. Soil inoculation with a commercial strain of Rhizophagus irregularis and the indigenous AM community, isolated from re-vegetated mine rock spoil piles on the mine property, each resulted in increased root colonization and biomass in C. canadensis, E. macrophylla, and F. virginiana. There was no significant difference in the increase in plant biomass between the commercial product and indigenous AM community. When examining the plant community, the commercial AM had greater average hyphal (p = 0.006) and vesicular (p = 0.001) root colonization than the indigenous AM treatment. However, there was no significant variation in arbuscule colonization (p > 0.05) in the plant community following applications of commercial and indigenous AM. The findings suggest that the growth and survival of boreal plant species in mine overburden appears to benefit from AM associations, as the non-AM treatments had very little growth. To our knowledge, this is the first study to date that has contrasted the application of a commercial and indigenous AM community for the restoration of a boreal understory plant community. The results of this study serve as a practical indication that soil inoculation with AM can benefit boreal understory plant growth when applied as an amendment to boreal mine overburden.