Ecological Zones of the Canadian Rockies
Just like traveling from the equator to the north pole, we experience changing climatic conditions when we travel higher into the mountains. Perhaps you’ve experienced this for yourself, noticing that the temperature on a high mountain peak is colder than far below at the trailhead. In the Canadian Rockies, the changing conditions result in three different ecological zones; the montane, sub-alpine, and alpine zones. Each of these zones is home to its own complement of plants and animals, which sort themselves according to where their needs may be best met. In a place like the Canadian Rockies where there are multiple unique habitats found at different elevations, we experience an increase in species diversity within a relatively small region.
While some species are specialized and will only be found in one zone, others are capable of existing in a wide range of conditions and you’ll find them almost anywhere. Knowing about each of the three ecological zones will help you find plants and animals of particular interest.
Montane ZoneThe montane zone comprises the base of the Canadian Rockies, from the foothills to the lower slopes and valleys. Generally, this zone is known for thick forests and woodlands, which are broken up by sprawling meadow systems and winding rivers. Here you’ll find trees like lodgepole pine, Douglas fir, white spruce, and aspen in abundance. Meadow environments are favorites of songbirds, black bears grazing on berries and wandering elk herds. Wetlands are also common here, home to critters like moose, beaver, bald eagles and waterfowl. Larger predators like wolf, coyote and mountain lion all inhabit this zone, mastering the ebbs and flows of their prey.
On the western slope, the mountains receive more precipitation than in the east. Naturally, we see a slight change in composition of the plant life here, especially on the cooler and darker slopes. Trees like mountain hemlock have become more common, thriving thanks to snow patches lingering into early summer. The increased moisture also creates a special type of community known as the Columbia forest. These forests host trees which are atypical of the Rockies as a whole, such as red cedar and cottonwood, as well as a lush understory of shrubby plants and berry bushes like devil’s club and thimbleberry.
The montane zone makes up less than 10% of the region, yet has over-weighted importance for myriad creatures compared to higher elevation zones. For instance, these lands are critically important to wildlife during the winter. Elk, woodland caribou, mule deer, bison and bighorn sheep congregate in areas with less snow, followed closely by predators like wolves and mountain lions. The presence of aspen woodlands plays an especially vital role for elk in the wintertime, who regularly eat the photosynthetic bark when they don’t have easy access to grasses.
Humans and our infrastructure create challenges for montane areas. Towns like Banff, Jasper, and Canmore are located here, as well as the railroad and highway system. Two major natural events compete with development interests. The first is wildfire. Fire is an important feature in this region and is critical to the health of the ecosystem. Fire recycles nutrients in meadows and contributes to the existence of shrubs and grasses (important food and nesting resources for wildlife) within otherwise tree-choked forests.
The second natural event is traveling and migrating wildlife. Human infrastructure results in fragmentation of habitat, resulting in undesirable effects for wildlife, both seasonally as well as on a day-to-day basis. Balancing the needs of the natural world against our own is a necessary and ongoing conversation between municipalities, the parks, private citizens and corporations.
Subalpine ZoneTraveling higher in elevation, either by trail or road, you’ll enter the sub-alpine zone. Damp forests of spruce and fir dominate here, feeling much different from the relatively warm forests below. Tamarack shows up in this zone as well, notable for being a conifer that loses its needles each autumn, but not before entire forests turn a dazzling golden hue for several weeks. Subalpine forests are home to lynx, snowshoe hare, pine marten and owls. In some locations, woodland caribou may make an appearance, and even the mysterious wolverine is spotted on occasion.
Intermixed with forested stands are subalpine meadows. A favorite denizen of these open environments is the rotund hoary marmot, which spends significant portions of its day basking on rocks in the sunshine. Bighorn sheep and mountain lion can also be found here, as well as grizzly bears feeding on sedges and berries. Elk are present too, happily grazing in both the forest and meadow areas. Moose are particularly fond of meadows containing small creeks and streams, as willows–their preferred food–are found in abundance in riparian zones.
The upper limit of the subalpine zone is better known as treeline, where trees no longer grow. Trees in this zone are limited by water, wind, temperature and lack of nutrients in the poor soils.
On average, treeline is around 7,500 feet in the Canadian Rockies, and higher as you travel south. In reality, it’s a fuzzy line, where geology and climate meld and merge in an erratic intermingling fashion, either favoring or foiling the growth of trees. You can see this gradient for yourself as you travel higher in elevation. Notice how trees become stunted and grow lower to the ground. This is a good indication that those trees are nearing the upper limit of where they can eke out a living. If you enjoy using interesting words to describe nature, then try out the ecological term krummholz, a German word that translates to “crooked wood,” referring to the twisted, diminutive shapes of trees near treeline.
Alpine ZoneVisiting the alpine zone demands a sense of adventure, if not a decent level of fitness. By human standards, it is a harsh environment. It is windy, exposed, and often cold, trading lush forests for sheer rocky cliffs and craggy peaks. Snowfields linger well into the summer, thanks to the cold temperatures, and there are many small glaciers tucked about. The presence of all that snow and ice keeps nearby soils cool and moist year-round when they aren’t completely frozen. Other soils, particularly on steeper slopes, are sandy and rocky, with very little water at all.
Plants and wildlife, however, still thrive. Species exist here not despite the conditions, but because of them, flourishing where others cannot. They have evolved specifically for the alpine environment and are just as comfortable here as you would be in your own home.
Notable wildlife includes mountain goat and bighorn sheep, elk, bears, golden eagle, wolverine, least weasel and the always amusing pika. Pika are an adorable mammal related to rabbits, spending their days eating and storing grasses and forbs. When wandering along meadow edges, particularly in rocky areas, you’ll hear their alarm calls- high-pitched chirps–that will alert you to their presence. Pika are especially sensitive to heat, and often hide in their subterranean dens in the middle of the day even at these high elevations. They are much better adapted to the cold than the heat.
The dominant vegetation communities of the alpine zone are tundra and alpine meadows, each characterized by stunning wildflowers and flowering shrubs. But you’ll need to get down on your belly to truly appreciate them. That’s because most of the plants in the alpine zone exhibit dwarfism. They are small cousins to plants of lower elevations. It makes good sense to be small in this high mountain environment; it’s easier to stay protected from desiccating winds, less food and water are required to grow, and there are lower energetic demands for reproducing in such a short growing season. These plants are genetically hard-wired to grow in their dwarfed forms. Even if cultivated in a low-elevation greenhouse they will always stay small and low to the ground. In the alpine zone, you just might be looking at an old-growth forest that is only a few inches high!
Despite the small stature of these plants, they have outsized importance in that they offer food, shelter, and nesting opportunities for a rich diversity of wildlife living in the high mountains. Colorful wildflowers provide nectar for countless insects, while the insects themselves assure each plant is properly pollinated. Lemmings rely on seeds as their main source of food, and use the protection of lichens and dwarf-shrubs to evade predators like northern harrier and coyote. Rosy finches and horned lark forage for seeds for food. Other small birds rely on small fruiting shrubs such as bilberry, while the plants rely on the birds for seed dispersal. Even larger animals like mountain goat rely on pint-sized alpine plants as food. In these ways, the alpine ecosystem, despite it seeming like a difficult environment, is beautifully in harmony at the roof of the Rockies.