Revegetation of disturbed lands: establishing native plant communities on borrow pits in northern Manitoba

The historical occurrence of hydroelectric development in northern Manitoba has resulted in disturbed areas without vegetative cover within the boreal forest. These disturbed areas exhibit conditions detrimental to restoration, including compacted soil lacking in nutrients, and organic matter and possessing low water-holding capacities. Northern climate conditions and short growing seasons further inhibit recovery potential. The study objective was to develop a strategy for encouraging self-sustaining native plant communities on borrow areas in northern Manitoba. Using fertilizer and mycorrhizal inoculations, seeding, transplants and cuttings were carried out using locally sourced plant species. Soil nitrogen, phosphorus, organic matter content, pH and electrical conductivity were analyzed for differences among treatments and the surrounding undisturbed forest to determine the impacts of material extraction on the land. Plant number, height, leaf area, chlorophyll fluorescence, chlorophyll a + b and total proteins as a proxy for stress were used to determine plant suitability for revegetation. Additionally, the height of trees planted by Manitoba Hydro and monitoring of the natural revegetation were performed over the duration of the experiment. Results of this study show transplantation as the most effective planting method due to the lower survival of seeds and cuttings. Successful establishment of Fragaria virginiana and Rubus idaeus transplants was observed. Inorganic fertilizer application resulted in increased leaf area and height of some species. Soil nutrients were significantly higher in fertilized plots although no significant differences were identified in the number or stress of plants between treatments. Differences in soil nitrogen, phosphorus and pH were found between the borrow pits and undisturbed forested areas. Inoculation with Oidiodendron maius increased survival of transplanted Vaccinium uliginosum and Vaccinium vitis-idaea. Natural revegetatio