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

Table 13 . Ecological moisture regime classes (Walmsley et al . 1980) . AWSC=available wate rstorage capacity .Moisture Regime Classxeric - very dry, little precipitation or highevapotranspiration, very low AWS Csubxeric - dry, low AWSCmesic - moist, intermediate to high AWSCsubhygric - moist to wet, variable AWSC ,seasonal seepag ehygric - wet, variable AWSC, permanen tseepagesubhydric - wet, variable AWSC, excesswater most of the tim ehydric - very wet, standing waterconstantl ySoil Drainagevery rapidalthough the bases and methods of recognition differ . V .t .s were delineated by tabular compariso n(Mueller-Dombois and Ellenberg 1974) and by both indirect ordination (Wisconsin ordination, Cot -tam et al. 1974) and direct ordination (direct gradient analysis, Whittaker 1973b) . Both serai and climaxv .t .s were recognized . In v .t . names, a hyphen (-) separates species in the same layer ; a virgul e(/) separates layers . Appendix E lists the v .t .s of MRNP and GNP .rapidwell to moderately wel limperfectpoorvery poo rECOREGIONSVegetation is used as the basis for the definition of Ecoregions in the ecological land classification .Ecoregional divisions reflect macroclimate and thus, vegetational features, which primarily reflect climaticfactors, rather than, for example, edaphic factors, are used to define Ecoregions . An Ecoregionis conceptually similar to the zone of Daubenmire (1968), La Roi (1975) and Lea (1980, 1983) ,the biogeoclimatic zone of Krajina (1965) and Utzig et al . (1983), the biophysical region of Lacate(1969), and the forest section of Rowe (1972) . Three Ecoregions are recognized in MRNP andGNP : Interior Cedar-Hemlock, Engelmann Spruce-Subalpine Fir, Alpine (Fig . 6) .INTERIOR CEDAR-HEMLOCK ECOREGIONThe Interior Cedar-Hemlock Ecoregion (ICH) is characterized by v .t.s dominated by Tsuga heterophyllaand Thuja plicata . It occurs from the lowest elevations in the parks, about 550 m in MRNPand about 830 m in GNP, to approximately 1500 m in MRNP and 1450 m in GNP . The upperboundary is a bit lower on cooler, northerly and easterly aspects and a bit higher on warmer, southerlyand westerly aspects. Typical v .t.s include : western hemlock-western red cedar/western yew/oa kfern (C50), western red cedar-western hemlock/devil 's club/oak fern (C51), western hemlock-westernred cedar-(Douglas fir)/mountain lover (C52), and Douglas fir-western red cedar/mountain love r(C53) . Tsuga heterophylla and Thuja plicata typically dominate mature v .t .s, while Pseudotsuga menziesii,Pinus monticola, and Picea engelmannii are usually seral species in the ICH . East of the BeaverRiver in GNP, the climate is drier than in MRNP or the rest of GNP . This is reflected in thevegetation, e.g . by the occurrence of Pinus contorta, which is absent further west and the restrictionof Thuja plicata and Oplopanax horridum to wetter sites .The Interior Cedar-Hemlock Ecoregion corresponds to the Northern Columbia Forest Section (CL .2)of Rowe (1972) . The ICH west of the Beaver River in GNP and in MRNP corresponds largely t othe Wet Interior Cedar-Hemlock Subzone (ICHb) of the biogeoclimatic classification of the Britis hColumbia Ministry of Forests (Utzig et al. 1983) . This also corresponds to the Western Wet Sub -montane Interior Cedar-Hemlock Subzone (ICHw) and Western Wet Montane Interior Cedar-HemlockSubzone (ICHv) described for an area just west of MRNP (Lloyd 1983) . The ICH Ecoregion i nMRNP and west of the Beaver River in GNP appears somewhat drier than the ICHb Subzone . I nparticular, Oplopanax horridum is less common and Vaccinium membranaceum is more common thanindicated by Utzig et al. 1983) .34