ABSTRACT: Soil characteristics of naturally saline toposequences in the boreal forest.

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Abstract

Boreal forest trees have been found growing on sites with high salinity (> 10 dS/m) at depth (80-100 cm) (Purdy et al. 2005), causing optimism for reclamation of salt affected landscapes in the boreal forest. However, little is known about the soil characteristics or forest productivity in these stands. We examined five naturally saline sites in Northern Alberta and measured soil characteristics along a toposequence from forest edge to forest interior. Soils were classified and described according to the Land Capability Classification System (Leskiw 2004). Soil samples were analyzed for electrical conductivity and sodium absorption ratio in saturated paste extracts, and pH in water. At all sites, salinity and sodicity decreased with increasing distance from the forest edge. Although salinity at depth (50-100 cm) was as high as 23 dS/m under a white spruce (Picea glauca [Moench] Voss) stand and 15 dS/m under aspen (Populus tremuloides Michx.), the salinity in the upper 20 cm in forested soils remained below 4 dS/m in all sites. Sodium absorption ratios as high as 63 for spruce and 17 for aspen, and pH > 8.5 were measured at 50-100 cm. Sodic soil (SAR = 13) was also found in the upper 20 cm under both forest types. Despite the challenging soil conditions that aspen and spruce face in these naturally saline landscapes, reasonable forest stands exist, suggesting that these species have some ability to avoid and/or tolerate salinity and sodicity. Ongoing work at these sites will examine forest productivity, foliar nutrients, root depth and density, and soil nutrients, moisture, and water table levels.

Bibliography of Canadian Geomorphology