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

Table 1 . Temperature (°C) ranges of selected western Canadian stations . (Atmospheri cEnvironment n .d.a & n .d .b )StationWarmes tMonthDailyiColdestMonthMeanAnnua lRangeExt .Max .Ext .Min .Ext .RangePrince Rupert 13 .5 1 .7 11 .8 32 .2 -21 .1 53 . 352 mPrince George A 15 .1 -12 .1 27 .2 34.4 -50.0 84 .4676 mRevelstoke 19 .0 -6 .1 25 .1 40.6 -34.4 75 .0456 mMount Fidelity 11 .1 -9.5 20.6 27 .8 -30.5 58 . 31875 mRogers Pass 13 .3 -10 .9 24.2 32.8 -38 .9 71 . 71323 mYNP Boulder Ck . 15 .3 -10 .9 26.2 33 .0 -35 .0 68 .01219 mBanff 14.8 -11 .5 26.3 34 .4 -51 .1 85 . 51397 mEdmonton Intl . A 15 .8 -16 .5 32.3 35 .0 -48 .3 83 .3715 mCLIMATE AND ECOREGIONSAltitude plays a major role in modifying regional climate and its effects are especially noticeable i nmountainous areas (]Chapman 1952) . Vegetation, as a biotic component of an ecosystem, reflects elevationalcontrols on climate . Thus, vegetational features have been used to delimit climatic units .Based primarily on vegetational physiognomy and composition, four units have been delineated : InteriorCedar-Hemlock Ecoregion, Engelmann Spruce-Subalpine Fir Ecoregion with Lower Subalpineand Upper Subalpine portions, and Alpine Ecoregion .INTERIOR CEDAR HEMLOCK ECOREGIO NMost of the climatic data for MRNP and GNP are from the Interior Cedar-Hemlock Ecoregio n(Tables 2 and 3), which is warmest and driest although much wetter than its elevational counterpar t(Montane Ecoregion) in the Rockies. Mean annual temperature is >1°C but the Interior Cedar- -Hemlock experiences the greatest temperature range with extreme minima of -30° to -35°C and mea nminima of -10° to -15°C . Mean maxima are 21° to 28°C and extreme maxima have reached 40°C at th elowest elevations (Table 2) . Summer frost at Glacier is less frequent than at Banff or Radiu m(Atmospheric Environment 1975a), which indicates mild climate . Various inversions (Janz and Storr1977) likely occur . The result, particularly of diurnal inversions common in summer, is cold ai rdrainage to valley bottoms and a thermal belt with warmer temperatures on valley walls . Cold airdrainage is likely pronounced in valleys below glaciers .Mean annual precipitation in the Interior Cedar-Hemlock is 1000 to 1700 mm with most occurring i nwinter (Table 3) . Minimum precipitation occurs in April or May and again in July to August or occasionallySeptember. June precipitation is consistently greater than in other spring and summe rmonths and often equals precipitation of late winter and early fall months . Mean annual snowfall is5