Ecological Land Classification of Mount Revelstoke and Glacie r ...

and Al, has accumulated . Two of the three Podzolic great groups are well to moderately well draine dand occur in MRNP and GNP . Humo-Ferric Podzols have podzolic Bf horizons (generally >0 .6%pyrophosphate-extractable Fe + Al and 5% organic carbon) . It is often difficult todistinguish the two great groups without laboratory data .Humo-Ferric Podzols are the most extensive of the two great groups, occurring with codominant o rdominant Dystric Brunisols tinder forest vegetation, with codominant Dystric and Sombric Brunisol sand, less often, Humic Regosols, under avalanche vegetation, and with codominant Dystric andSombric Brunisols under Alpine and Upper Subalpine vegetation . Well drained areas with few or noPodzolic soils are recent landscapes with incipient soils ; landslides with rubbly, coarse textured andfragmental soils ; Alpine colluvium derived from Lardeau Group rocks ; and at low elevations in th eInterior Cedar-Hemlock Ecoregion on southwesterly aspects above Revelstoke townsite and on th eeast wall of the Beaver River valley . The latter areas are the warmest and driest in MRNP and GNP ,based on vegetational features . This mesoclimate coupled with certain parent material features - re -cent eolian veneers in the Revelstoke area and colluvium or till derived from Horsethief Creek Grou pstrata in the Beaver River area - are less conducive to podzolization than elsewhere in the parks .Orthic Humo-Ferric Podzols, the predominant subgroup, generally have friable or very friable podzolicB horizons underlain by thick, weak BC horizons that are transitional to noncalcareous C horizonswhich begin at depths often >1 m . Sometimes, Bm horizons occur between Bf and BC horizons. Thin (10 cm) Ah horizons, likely had the horizon thickened physically by pedoturbation .Orthic Ferro-Humic Podzols are related to the above subgroups . They occur, as codominants or accessorysoils, in Alpine and Upper Subalpine landscapes under tundra and meadow vegetation and inavalanched terrain . Bhf horizons of varying thickness frequently develop under Ah and Ahe horizon sand often have higher cation exchange capacity (CEC) than horizons above or below . Occasionally, athick Ah horizon (Sombric Ferro-Humic Podzols) may occur . In some landscapes however, differentiatingAh from Bhf is difficult . Under forest, Orthic Ferro-Humic Podzols occur most often as accessorysoils where soils are shallow to bedrock . Illuvial humus appears to accumulate above the bed -rock contact, occasionally in sufficient amounts to be classed as a Bhf horizon . In a few shallowsoils, discontinuous layers of black humus (H horizon) 3 cm thick, the horizon isortstein, labelled Bfc (occasionally Bhfc) and the soil is an Ortstein Humo-Ferric Podzol (occasionall yOrtstein Ferro-Humic Podzol) . Ortstein Humo-Ferric Podzols are codominant in Lower Subalpinemorainal landforms derived from Hamill Group bedrock . They are subdominant on the same materialin the Interior Cedar-Hemlock and on morainal landforms in the Interior Cedar-Hemlock an dLower Subalpine of MRNP (Shuswap Metamorphic Complex) . In the Upper Subalpine on the samematerials, Ortstein Humo-Ferric Podzols are less common, occurring as accessory soils . Cementedsoils occur sporadically on stable fluvial landforms and are rare in colluvial landscapes .27