COS 87-7
Ectomycorrhizal fungal inoculum potential of surface reclamation materials in oil sands mining
In the Canadian boreal forest, surface mining for oil deposits has disturbed 715 square kilometers requiring subsequent reclamation. During this landscape level disturbance, critical mutualisms important for the growth and survival of boreal trees are disrupted. Specifically, ectomycorrhizas, the association between roots of most coniferous trees and ectomycorrhizal fungi, are severed during mining activities. Land reclamation nears completion with the placement of cover soils from substrates locally available and shown to vary in propagules of plant species present. The ectomycorrhizal fungal inoculum potential of these cover soils in combination with host specificity has not been investigated. Towards this goal we used field and growth chamber experiments to test the inoculum potential of three commonly used cover soils: selectively salvaged forest floor material, peat, and subsoil. Into each of these materials we planted seedlings of Pinus banksiana, Picea glauca, or Populus tremuloides, tree species common in this region of the boreal forest. We characterized the ectomycorrhizal fungal community colonizing roots of seedlings using Sanger sequencing, along with measuring seedling growth and nutrient acquisition.
Results/Conclusions
Ectomycorrhizal fungal community composition on seedlings was partitioned by host species regardless of cover soil in the field, and by both host species and cover soil in the growth chamber. Amphinema spp. and Hebeloma spp. were recovered from both field and growth chamber experiments. Cenococcum spp., Tuber spp., and Tomentella spp. were found colonizing roots of seedlings grown in the greenhouse, while Wilcoxina spp., Rhizopogon spp., and Thelephora terrestris were found on roots of seedlings grown in the field. Amphinema spp. was found to only associate with P. glauca and Thelephora terrestris with P. banksiana, while other ectomycorrhizal fungi were found to associate with 2 or 3 hosts. Average percent fungal colonization of roots and ectomycorrhizal fungal richness per seedling across both studies were similar and relatively low (~23% and 1-2, respectively). Results imply that host species selection is more important for recovering ectomycorrhizal fungal diversity than the selection of the cover soil in the field, while both host and cover soil are important for recovering ectomycorrhizal fungi in the greenhouse. Forest restoration practices might want to consider broadening the selection of native species established on reclamation areas for the recovery of a diverse community of important belowground mutualisms, while continuing to monitor the influence of cover soil over time.