British Columbia Mine Reclamation Symposium

Soil productivity and forest regeneration success on reclaimed oil and gas sites in the Dawson Creek Forest District Bulmer, Charles Ernest; Krzic, Maja; Green, Korey; Suderman, Dale; Radchenko, Garry; Gevatkoff, Paul


We visited 27 reclaimed oil and gas well sites in northeast BC that were decompacted and planted with lodgepole pine between 1994 and 1999. The reclamation work was carried out as part of an effort to gain experience with reforestation as a potential strategy for improving abandoned oil and gas sites. Reclamation techniques included decompaction either with a winged subsoiler or a ripper, seeding a cover crop, fertilizing, and planting to lodgepole pine, which has previously been successful in reclamation of forestry disturbances. Of the 27 sites, three (11.1 percent) had been re-used by drilling rigs, and an additional site was re-used as a forest landing. We evaluated tree growth on 19 of the well sites, and collected detailed information on vegetation cover, ecological and soil conditions. Clay content for the sampled sites ranged from 0 to 40 percent and bulk density from 594 to 1803 kg/m³. Soil chemical properties (C, N, available P, pH) were very similar to conditions found on nearby forest plantations and rehabilitated landings. Values of soil mechanical resistance in the rooting zone during July exceeded values that are expected to be growth-limiting on several plots, but values in June were below the threshold of 2500 kPa. Approximately 50 percent of the plots had stocking levels above 600 stems per hectare. Subplots with subhydric, hygric and subhygric moisture regime appeared to have generally lower stocking levels than subplots with mesic and submesic moisture regime. Average stocking levels for well sites were lower than for rehabilitated forest landings and undisturbed plantations on similar sites in the BWBS, and the trees on the well sites were smaller than trees planted on landings that had similar site conditions. Field observations suggested that factors such as competition from seeded cover crops, moisture regime, selection of tree species, and well site construction / rehabilitation techniques affected seedling survival and growth on individual sites. Where soil and site conditions are suitable, tree planting appears to be a useful technique that would enhance environmental values over the long term. To obtain the maximum benefit from reforestation efforts on well sites, a targeted approach is suggested, where efforts are directed at sites with the highest likelihood of success. This operational reforestation work has provided some key lessons that can be used to improve reforestation success on reclaimed oil and gas sites in the future.

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