Nutrient distribution in sandy soils along a forest productivity gradient in the Athabasca Oil Sands Region of Alberta, Canada

Brunisolic soils developed on sandy deposits comprise a significant portion of the land disturbed by surface mining in the Athabasca Oil Sands Region. These soils support forest communities ranging from nutrient limited jack pine to more productive aspen stands. The objective of this study was to determine if and how the physical properties of these sandy soils influence the accumulation and distribution of soil nutrients. Sixteen sites, selected to capture the natural range in forest productivity of the area, were characterized to assess particle size distribution, total and available nutrient stocks in forest floors, total C and N, and extractable nutrients in B horizons. Under jack pine, relatively small decreases in sand content of the upper soil profiles, from 97% to 88%, were associated with greater total nutrient stocks and lower C/N ratios in the forest floors. In soils under aspen, forest floor nutrient stocks related most strongly with texture of the B horizons, with finer B horizons (from 94% to 78% sand) leading to larger forest floor nutrient stocks. These results indicate that textural characteristics play an important role in nutrient cycling of these sandy soils and should be a primary focus during their reclamation.