Germination, growth and gas exchange of selected boreal forest seedlings in soil containing oil sands tailings

Greenhouse experiments were conducted to determine the effects of soil enri ched in fine tailings (FT), produced by the oil sands extraction, on germin ation, seedling growth and physiology of several plant species of the borea l forest. The germination of seeds was initially delayed by 15% FT in dogwo od (Cornus stolonifera Michx) and jack pine (Pinus bankisiana Lamb) but not in white spruce [Picea glauca (Moench) Voss]. In the second set of experim ents we showed that all dogwood seedlings survived 6 months of treatment wi th 15% FT while the survival rates of raspberry, jack pine and white spruce seedlings were reduced to 44, 55 and 94%, respectively. FT reduced root an d shoot dry weights in raspberry seedlings and the number of lateral shoots in jack pine and white spruce seedlings. In raspberry and jack pine seedli ngs, reductions of gas exchange were recorded. The results of our study sug gest that the modifications of soil chemistry, texture and structure by FT may all contribute to the observed phytotoxic effects. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.