Enhanced Revegetation and Reclamation of Oil Sands Disturbed Sites Using Actinorhizal and Mycorrhizal Biotechnology

C.W. Greer
N. Onwuchekwa
Janusz Zwiazek
A. Quoreshi
S. Roy
Francis Salifu
Damase Khasa
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A functional soil microbial community is crucial for plant growth and survival and a key component for successful land reclamation. Mycorrhizal fungi, a component of the microbial community, play an essential role in plant nutrient uptake, water relations, and buffer plants against biotic and abiotic stresses to enhance ecosystem establishment. Actinorhizal bacteria, such as Frankia spp., another component of the soil microbial community, help plants establish in nutrient poor soils by supplying plants with atmospherically fixed nitrogen. Newly reconstructed landscapes after oil sands exploitation may be characterised by low soil organic matter, high salinity and alkalinity, low nutrient status, and limited microbial activity. Several organic amending materials are used to cap reconstructed soils in order to support plant community establishment. However, landscape disturbance may result in destruction of mycorrhizal fungal networks and affect actinorhizal bacterial numbers in soil. Therefore, ensuring the development of functional symbioses in trees and shrubs during greenhouse production before outplanting, is an important biotechnological approach to the reclamation of oil sands disturbed lands. In the present study, actinorhizal alders (Alnus viridis ssp crispa and A. incana ssp. rugosa) and ectomycorrhizal fungi (ECM) inoculated Jack pine (Pinus banksina Lamb.) and White spruce (Picea glauca (Moench) Voss) seedlings were outplanted on the Suncor MD5 reclaimed overburden site. The study was designed to evaluate the impact on survival and growth of inoculating plants prior to outplanting. The seedling volume index (SVI) or plot volume index (PVI) were used to evaluate field performance and compare inoculated verses uninoculated plants. In all cases inoculated plants outperformed uninoculated plants. Inoculated alders had a SVI that was 3- to 4-fold greater than uninoculated plants. In addition, alder rhizosphere bacterial populations showed increases in diversity and catabolic activity. There were significant increases in the PVI of ECM inoculated white spruce and jack pine seedlings when compared with uninoculated controls. These preliminary results, after two growth seasons, show promise in the use of pre-inoculated seedlings in enhancing growth and establishment of alders and conifers on oil sands reclamation sites. Knowledge gained from this research will increase our understanding of actinorhizal and ECM symbioses with forest seedlings on reclamation sites and their ability to accelerate successful revegetation and reclamation.