At present, reforestation has focused on native forests with anthropogenic intervention and eroded soils. There is interest in producing Nothofagus seedlings which can overcome adverse conditions encountered on reforestation sites. It is necessary to find new fungi that can be utilized as mycorrhizal inoculants and that enable the seedlings to increase their tolerance to adverse conditions. Two ectomycorrhizal strains of the fungus Descolea antarctica (D1 and D2) were cultured at different temperatures, pH levels and the activities of amylases, cellulases, and phosphatases were determined. In greenhouse and nursery trials, the growth responses of inoculated Nothofagus obliqua seedlings were evaluated. D1 and D2 exhibited the highest growth rates at 23ºC. Both strains grew at pH levels from 4 to 11. The highest enzymatic activities were registered for amylase (57.2 mg glucose/ml * g of mycelium * hr) and acid phosphatases (58.1 mg p-nitrophenol/ml * g of mycelium * hr) at 37ºC, and acid phospatases (1.720 mg p-nitrophenol/ml * g of mycelium * hr) and alkaline phosphatases (1.360 mg p-nitrophenol/ml * g of mycelium * hr) at pH 4 and pH 11, respectively. We conclude that suitable N. obliqua seedlings for use in reforestation were obtained using D2 as inoculant.