BACKGROUND - Canadian Rockies: Including Banff and Jasper National Parks - page 500

arch” is formed as the clear air clashes with the warmer cloud-laden winds. The
phenomenon is most common in southern Alberta but occurs to a lesser degree as
far north as the Peace River Valley. Pincher Creek, the gateway to Waterton Lakes
National Park, experiences about 35 chinooks each winter.
Flora
Botanists divide the Canadian Rockies into three distinct vegetation zones (also called bio-
mes ): montane, subalpine, and alpine. The boundaries of these zones are determined by
several factors, the most important being altitude. Latitude and exposure are also factors,
but less so. Typically, within any 1,500 meters (4,920 feet) of elevation change, you'll pass
through each of the three zones. These changes can be seen occurring most abruptly in
Waterton Lakes National Park. Conifers (evergreens) predominate in the montane and sub-
alpine, whereas above the tree line, in the alpine, only low-growing hardy species survive.
MONTANE
The foothills, along with most major valleys below an elevation of about 1,500 meters
(4,920 feet), are primarily cloaked in montane forest. Aspen, balsam poplar, and white
spruce thrive here. Lodgepole pine is the first species to emerge after fire. Its hard seed
cones are sealed by a resin that is melted only at high temperatures. When fire races
through the forest, the resin melts and the cones release their seeds. The lodgepole is
named for its straight, slender trunk, which natives used as a center pole for tepees. On
dry, south-facing slopes, Douglas fir is the climax species. Where sunlight penetrates the
forest, such as along riverbanks, flowers like lady's slipper, Indian paintbrush, and saxi-
frage are common. Large tracts of fescue grassland are common at lower elevations. The
montane forest holds the greatest diversity of life of any vegetation zone and is prime
winter habitat for larger mammals. But this is the habitat where most development occurs
and therefore is often much changed from its natural state.
SUBALPINE
Subalpine forests occur where temperatures are lower and precipitation higher than in the
montane. In the Canadian Rockies, this is generally 1,500-2,200 meters (4,920-7,220 feet)
above sea level. The upper limit of the subalpine zone is the tree line. Approximately