Sanborn, P., Lamontagne, L. and Hendershot, W. 2011. Podzolic soils of Canada : Genesis, distribution, and classification. Can. J. Soil Sci. 91: 843–880. Podzolic soils occupy 14.3% of the Canadian landmass, and occur in two widely separated areas, eastern Canada (northern Ontario, Quebec, Maritimes) and British Columbia, usually under coniferous forest and on non-calcareous parent materials. Broad climatic control of Podzol distribution and properties is evident at the national scale, with higher organic matter concentrations (Ferro-Humic Podzols) in wetter climates, in contrast to Humo-Ferric Podzols predominating in drier boreal forest regions. Humic Podzols are least abundant and are restricted to the wettest landscape positions. International and Canadian research suggests that a more diverse range of processes is involved in podzolization than was envisioned in the 1960s, and proposed mechanisms must account for observed patterns of organic matter distribution and a diverse array of inorganic amorphous constituents in profiles. Taxonomic concepts of Podzolic soils in the Canadian System of Soil Classification have remained consistent since the late 1970s, and the higher-level criteria defining the order and its great groups have proved to be meaningful in new applications, such as delineating soil carbon stocks across Canadian landscapes. Canadian contributions to pedological research on Podzols declined dramatically after 1990, coincident with shifting research priorities in soil science and diminished activity in soil survey.

This study provides estimates of N2 fixation in biological soil crusts (BSCs) from shrub–steppe grasslands in British Columbia’s Chilcotin plateau. We identify key seasonal periods and environmental conditions during episodes of BSC nitrogen-fixation activity. Predicted nitrogen-fixation activity showed two peak periods: one during late winter and early spring snowmelt events, and the second during summer precipitation events. BSC nitrogen fixation, especially summer activity, was quite variable from year to year. The magnitude of predicted nitrogen fixation at the landscape level was dependent upon the ratio used to convert rates of acetylene reduction to nitrogen fixed. Using a theoretical ratio of 3:1, estimates of average annual BSC nitrogen fixation were 1.0 kg N·ha−1. However, using a conversion ratio of 0.06, obtained from side-by-side measurements of acetylene reduction and 15N uptake, annual estimates are 52 kg N·ha−1. These estimates are based on assessments of the aerial extent of dark BSC communities, which at the Farwell Canyon study site exceeded 50%. The fate of fixed nitrogen, especially during the late winter period, when underlying soils are frozen, remains unclear.

McConkey, T., Bulmer, C. and Sanborn, P. 2012. Effectiveness of five soil reclamation and reforestation techniques on oil and gas well sites in northeastern British Columbia. Can. J. Soil Sci. 92: 165–177. Techniques developed for forestry landing reclamation were applied to five oil and gas well sites in northeastern British Columbia to ameliorate soil and facilitate reforestation. Treatments implemented in fall 2003 and spring 2004 were tillage, wood chip mulch, tillage+wood chip mulch, tillage+incorporated wood chips, brush mats and a control. Lodgepole pine (Pinus contorta var. latifolia) and white spruce (Picea glauca) seedlings were planted. Soil and vegetation were assessed (bulk density, soil mechanical resistance, water content, air filled porosity, water retention, least limiting water range, nutrient availability, seedling survival and growth) throughout 2004 and 2005 growing seasons. Tillage improved soil physical condition, reducing soil mechanical resistance and bulk density; treatments did not affect soil chemical properties. Treatments did not significantly affect species survival; after 6 yr, spruce height and root collar diameter improved with tillage but treatments did not affect pine. Brush mats led to increased spruce growth. Regression relationships between tree performance and soil condition were significant, but generally did not explain large variability. More elaborate soil physical condition measures were no better than bulk density for predicting seedling performance, but relative bulk density and least limiting water range may be useful for evaluating soil productivity.

Dampier, L., Sanborn, P., Smith, S., Bond, J. and Clague, J. J. 2011. Genesis of upland soils, Lewes Plateau, central Yukon. Part 2: Soils formed in weathered granitic bedrock. Can. J. Soil Sci. 91: 579–594. Polygenetic soils have formed on weathered granitic bedrock at high elevation (>1200 m asl) beyond the penultimate glacial limit on the Lewes Plateau in central Yukon Territory. Solum thickness in four Brunisols that were examined exceeds the depths of excavated pits (85–110 cm), but data indicate limited chemical weathering. Clay mineralogy is dominated by vermiculite and kaolinite. Smectite and chlorite are present in horizons derived, respectively, from residuum and colluvium. Sola are strongly cryoturbated, in spite of the lack of permafrost at these sites today. Three scenarios are proposed to explain these soils: preservation of relict soil features beneath cold-based ice, prolonged interglacial soil formation following erosion of till deposited by warm-based ice, and ice-free conditions throughout the Quaternary, with soil evolution shaped by multiple glacial-interglacial cycles.

Dampier, L., Sanborn, P., Smith, S., Bond, J. and Clague, J. J. 2011. Genesis of upland soils, Lewes Plateau, central Yukon. Part 1: soils formed on Pleistocene glacial deposits. Can. J. Soil Sci. 91: 563–578. We describe and interpret nine upland (>1000 m asl) Dystric Brunisols and one Humo-Ferric Podzol formed on till of the McConnell [Marine Isotope Stage (MIS) 2] and penultimate (MIS 4 or 6) glaciations on the Lewes Plateau of central Yukon Territory. Unlike soils formed on correlative glacial deposits at lower elevation in the nearby Tintina Trench, the soils on the Lewes Plateau display only weak age-related differences. Penultimate and McConnell soils have solum thicknesses of 50–75 cm and <50 cm, respectively, but other morphological and chemical properties do not differ between the two age groups. Smectite is present in the McConnell soils; it was previously reported only in soils formed on Early Pleistocene glacial deposits in central Yukon and was interpreted to reflect weathering and soil formation during warm interglaciations. Paleoclimatic interpretations of clay mineralogy in central Yukon may be confounded by differences in parent material provenance and should be reassessed. This study shows that field soil characteristics alone are insufficient to differentiate McConnell and penultimate glacial deposits in upland landscape positions on the Lewes Plateau.