Article

Recreating a Functioning Forest Soil in Reclaimed Oil Sands in Northern Alberta: An Approach for Measuring Success in Ecological Restoration

Dep. of Forest Sciences, Univ. of British Columbia, 3041-2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
Journal of Environmental Quality (Impact Factor: 2.65). 07/2009; 38(4):1580-90. DOI: 10.2134/jeq2008.0317
Source: PubMed

ABSTRACT

During oil-sands mining all vegetation, soil, overburden, and oil sand is removed, leaving pits several kilometers wide and up to 100 m deep. These pits are reclaimed through a variety of treatments using subsoil or a mixed peat-mineral soil cap. Using nonmetric multidimensional scaling and cluster analysis of measurements of ecosystem function, reclamation treatments of several age classes were compared with a range of natural forest ecotypes to discover which treatments had created ecosystems similar to natural forest ecotypes and at what age this occurred. Ecosystem function was estimated from bioavailable nutrients, plant community composition, litter decomposition rate, and development of a surface organic layer. On the reclamation treatments, availability of nitrate, calcium, magnesium, and sulfur were generally higher than in the natural forest ecotypes, while ammonium, P, K, and Mn were generally lower. Reclamation treatments tended to have more bare ground, grasses, and forbs but less moss, lichen, shrubs, trees, or woody debris than natural forests. Rates of litter decomposition were lower on all reclamation treatments. Development of an organic layer appeared to be facilitated by the presence of shrubs. With repeated applications of fertilizers, measured variables for the peat-mineral amendments fell within the range of natural variability at about 20 yr. An intermediate subsoil layer reduced the need for fertilizer and conditions resembling natural forests were reached about 15 yr after a single fertilizer application. Treatments over tailings sand receiving only one application of fertilizer appeared to be on a different trajectory to a novel ecosystem.

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Available from: Sylvie Quideau, Jan 14, 2016
    • "Excessive nutrient supply, commonly resulting from an application of conventional, water-soluble fertilizers, may result in a high concentration of soluble salts in the root zone (Shaviv and Mikkelsen, 1993;Trenkel, 1997). Furthermore, detection of relatively high or low nitrate levels in some fertilized stands in the oil sands region (Rowland et al., 2000) suggests the need to optimize fertilization operations to improve cost efficiency and decrease the risk of nutrient leaching to surface and underground water bodies (McMillan et al., 2007). Steady-state nutrition theory (Ingestad and Lund, 1986) suggests that seedling growth and nutrient uptake can be maximized and leaching losses minimized by supplying nutrient quantities in proportion to plant requirements. "
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    ABSTRACT: Field fertilization during reforestation often yields variable results, particularly on harsh restoration sites. An improved understanding of the recovery of applied nitrogen (N) under different fertilization practices should aid in developing more effective fertilizer prescriptions. We evaluated field establishment of white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuloides Michx.) seedlings as well as N recovery within planted seedlings, soil, and competing vegetation on a mine reclamation site in the oil sands region of northern Alberta in response to immediately available fertilizer (IAF) and polymer-coated controlled-release fertilizer (CRF) applications. 15N-enriched urea was applied as IAF and as a polymer-coated CRF (20gNseedling-1 and 4gNseedling-1, respectively) to each species. Seedling survival, growth, and nutritional status, along with occurrence of competing vegetation and plant and soil 15N recovery were quantified after the first field season. Seedlings receiving CRF exhibited increased diameter and organ dry mass relative to the IAF and control treatments. Both IAF and CRF promoted comparable increases in seedling N status, and fertilizer type did not influence within-seedling 15N allocation. Neither IAF nor CRF affected vegetation cover or dry mass. Recovery of fertilizer-derived 15N was low, with much of the recovered 15N remaining in soils and only small amounts observed in seedlings and competing vegetation for both fertilizer treatments. Findings indicate that directed root zone application of CRF promotes first-year seedling growth and nutritional responses similar to or better than those induced by broadcast IAF applications, but at substantially lower N application rates. Our results suggest that a shift from broadcast IAF to targeted soil applications of CRF may produce similar or improved early seedling growth and nutrient uptake on reclamation sites, while greatly reducing overall quantities of N applied during the regeneration phase, much of which appears to be lost from the site of application regardless of fertilizer type.
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    • "The mean annual precipitation is 418 mm, with 283 mm occurring as rainfall during the growing season (Environment Canada, 2014). Details about reconstruction of soil profiles following oil sand mining can be found in Rowland et al. (2009) and Sorenson et al. (2011b). Briefly, soil profiles were reconstructed with surface salvaged organic and geologic materials removed during oil sands mining, and placed as a 10 cm cap of peat and 40 cm of mineral soil as a clean top layer (peat mineral mix; PMM). "
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    ABSTRACT: Examining the spatial interactions between above and belowground components of terrestrial ecosystems can give meaningful insight into the ecological processes happening at different scales. Understanding spatial dependence in these processes may help to evaluate reclamation success which is crucial for future management of such areas. The aim of this study was to measure the spatial patterns of soil biogeochemical properties in a young aspen stand reclaimed after oil sands extraction and to evaluate how the patterns were related to nutrient availability. Samples were collected from a 14-year old reclaimed site using a spatially explicit protocol with a minimum resolution of 0.5 m. Field-measured variables included forest floor depth and mass, tree cluster (canopy overlap), distance to nearest tree, and resin available nutrients. Soil microbial properties including microbial biomass C and N, basal respiration, and extracellular enzyme activity were measured during an eight-week laboratory incubation experiment. Geo-statistics were applied to examine the spatial patterns and model the space effect. A fine scale (< 10 m) spatial pattern was found for the majority of stand variables, soil microbial properties, and available macronutrients (N, P, S and base cations). Macronutrients such as N, P and S availability had a fine scale cyclic spatial association with soil microbial properties, with an 8–10 m oscillation, which indicated belowground control on these nutrients. Spatial regression models also suggested a stronger microbial influence on the availability of these nutrients when compared to stand characteristics. However, stand characteristics exhibited significant control on base cations and micronutrient availability through the effect of forest floor depth and tree clustering. Although nutrient availability showed strong spatial relationships with belowground processes in the studied reclaimed site, similar relationships with aboveground properties appeared to be weak, and might require further time to develop.
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    • "Coarse-textured TS is generally a poor plant growth medium because of its low water and nutrient holding capacities, which would often cause trees to be under water stress, especially in dry years. In the AOSR, oil companies used different capping depths depending on the substrate placed (Rowland et al., 2009) because there was no standard prescription for soil reconstruction. Placing thick cover soil layers with fine materials over coarse-textured TS layers could increase water holding capacity due to the high organic matter content in the peat material used as a cover soil and decreased infiltration induced by the capillary barrier between layers (Moskal, 1999; Barbour et al., 2007; Li et al., 2014). "
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