Comparison of Soil Structure Development for Reclaimed, Fire-Disturbed and Undisturbed Forested Soils Using Soil Physical Properties in Northern Alberta, Canada.

An area of recent interest is the development of soil structure in constructed anthropogenic soils.  Modern oil sands reclamation utilizes layering techniques and organic matter inputs to simulate natural pedogenesis processes; however, the innate development of secondary soil structure (aggregation) is still required for nutrient cycles and hydrology to reflect undisturbed sites. Numerous soil physical properties are heavily influenced by soil structure and behave as proxies to its development. Therefore, the objective of this study was to measure soil physical properties among several disturbed and undisturbed boreal sites, and develop a range of normally-occurring values within each treatment. Two reclaimed sites including an overburden dump (RA1 - Canadian Natural Resources Limited) and a tailings pond (Wapisiw Point - Suncor Energy) were selected for this study; both reclaimed sites utilize a two-layer, peat-mineral mix soil cover. In addition, two natural sites – a fire-disturbed and an undisturded forested site – were also chosen. The fire-disturbed site was included to examine the difference between anthropogenic and natural disturbance on a northern boreal landscape. Sampling will follow a stratified random transect design, with ten points being sampled along a linear transect for each treatment. At each point, a soil pit will be dug through the soil cover until the underlying material is reached, and horizontal sampling shelves will be cut into the soil pit for each cover layer. Measurements taken at each shelf will include: field-saturated hydraulic conductivity (K_fs) using a mini-disc infiltrometer, soil strength and an intact soil core (~5 cm diameter). Laboratory experiments using a tension table and pressure plates will derive available moisture capacity and pore-size distribution from the intact soil core. From this study, we hope to reveal the degree of soil structure development in reclaimed, anthropogenic soils, as well as similarities or differences in soil structure between natural and unnatural disturbances.