Seed germination in tailings cake and cake-reclamation substrate mixtures with oil sands process water

Abstract

We investigated the germination of 13 species commonly used in oil sands mining reclamation of boreal forest as influenced by substrate type (potting soil, tailings cake and mixtures of cake-sand, cake-peat and cake-forest floor mineral mix (FFMM)) and water quality (0, 50 and 100% oil sands process water). Germination responses clustered into three groups with trees and graminoids exhibiting the highest germination (84-99%), followed by shrubs and forbs with intermediate germination (46-69%), and the native forb species, Chamerion angustifolium, Achillea millefolium and Galium boreale, with the lowest germination (7-18%). Among substrates, potting soil supported the highest germination (69%), followed by cake mixed with peat (64%) or FFMM (63%), cake-sand (60%) and cake (57%). Concentrations of ions, e.g. sodium and chloride, were higher in cake and cake-sand than in cake-peat or cake-FFMM suggesting that mixing cake with FFMM or peat can alleviate salt stress and encourage germination. Process water had little or no effect on germination especially on cake and cake amendments possibly due to the high ionic content of these substrates. There were major differences in germination response among species. Trees and graminoids may be well suited for reclaiming oil sands tailings whereas native forbs may perform poorly when used for revegetating tailings.