Forest floor as an amendment in oil sand reclamation

Syncrude Canada Inc. and Suncor Energy Ltd. are two oil sand operators in the Athabasca region. Following surface mining, land reclamation entails re-establishment of functioning ecosystems using salvaged mineral soil materials and organic amendments. While traditional reclamation uses peat, benefits from using the forest floor stripped from pre-mining areas were examined. This study investigated the reclamation techniques in terms of nitrogen (N) fluxes. Specifically, net N nitrogen mineralization rates and microbial biomass were measured in an undisturbed forest and several reclaimed sites at Syncrude and Suncor. Results suggested no significant difference in net N mineralization rates between sites. However, there were differences in microbial biomass possibly related to differences in moisture content. A lab experiment manipulating soil moisture content showed a positive relationship between microbial biomass N and moisture content. No relationship with microbial biomass C was found, possibly due to a shift in microbial community structure.