Ectomycorrhizal fungal communities of nursery-inoculated seedlings outplanted on clear-cut sites in northern Alberta

Seedlings from three conifer species (Pinus contorta Doug. ex Loud. var. latifolia Englem., Picea glauca (Moench) Voss, and Picea mariana (Mill.) BSP) were planted on two clear-cut sites in Alberta, Canada, after inoculation in the nursery with strains of six different ectomycorrhizal species (Hebeloma longicaudum, Laccaria bicolor, Paxillus involutus, Pisolithus tinctorius, Rhizopogon vinicolor, and Suillus tomentosus). Five and 6 years after planting, morphological characterization and molecular typing techniques (internal transcribed spacer - restriction fragment length polymorphism (ITS-RFLP) and simple sequence repeat (SSR) markers) were used to identify the ectomycorrhizal fungal communities and to assess the occurrence of the inoculated ectomycorrhizal fungi on host roots. Ectomycorrhizae recovered from the roots of the planted trees on each of the two sites showed little diversity, with a total of 16 and 19 ITS-RFLP patterns corresponding to 11 and 13 ectomycorrhizal taxa, respectively. The most abundant ectomycorrhizal fungi found on colonized roots were ascomycetes and the widespread basidiomycete Amphinema byssoides. Amongst the six introduced fungal strains, only L. bicolor UAMH 8232 was detected on one site after 5 and 6 years, as determined using six SSR markers. Although not detected after 5 years, some of the introduced strains might have had a positive effect on the early growth of the trees before their replacement by competing species, because significant differences in plot volume index were detected between inoculation and control treatments.