Rocky Mountains - Ecology and Climate

Ecology and Climate

There are a wide range of environmental factors in the Rocky Mountains. The Rockies range in latitude between the Liard River in British Columbia (at 59° N) and the Rio Grande in New Mexico (at 35° N). Prairie occurs at or below 1,800 feet (550 m), while the highest peak in the range is Mount Elbert at 14,440 feet (4,400 m). Precipitation ranges from 10 inches (250 mm) per year in the southern valleys to 60 inches (1,500 mm) per year locally in the northern peaks. Average January temperatures can range from 20 °F (−7 °C) in Prince George, British Columbia to 43 °F (6 °C) in Trinidad, Colorado. Therefore, there is not a single monolithic ecosystem for the entire Rocky Mountain Range.

Instead, ecologists divide the Rocky Mountain into a number of biotic zones. Each zone is defined by whether it can support trees, and the presence of one or more indicator species. Two zones that do not support trees are the Plains and the Alpine tundra. The Great Plains lie to the east of the Rockies, and is characterized by prairie grasses (below roughly 1,800 feet (550 m)). Alpine tundra occurs in regions above the treeline for the Rocky Mountains, which varies from 12,000 feet (3,700 m) in New Mexico to 2,500 feet (760 m) at the northern end of the Rocky Mountains (near the Yukon).

The USGS defines ten forested zones in the Rocky Mountains. Zones in more southern, warmer, or drier areas are defined by the presence of pinyon pines/junipers, ponderosa pines, or oaks mixed with pines. In more northern, colder, or wetter areas, zones are defined by Douglas-firs, Cascadian species (such as western hemlock), lodgepole pines/quaking aspens, or firs mixed with spruce. Near treeline, zones can consist of white pines (such as whitebark pine or bristlecone pine); or a mixture of white pine, fir, and spruce that appear as shrub-like krummholz. Finally, rivers and canyons can create a unique forest zone in more arid parts of the mountain range.

The Rocky Mountains are an important habitat for a great deal of well-known wildlife, such as elk, moose, mule and white-tailed deer, pronghorns, mountain goats, bighorn sheep, black bears, grizzly bears, coyotes, lynxes, and wolverines. For example, North America's largest herds of moose is in the Alberta-British Columbia foothills forests.

The status of most species in the Rocky Mountains is unknown, due to incomplete information. European-American settlement of the mountains has adversely impacted native species. Examples of some species that have declined include western toads, greenback cutthroat trouts, white sturgeons, white-tailed ptarmigans, trumpeter swans, and bighorn sheep. In the United States portion of the mountain range, apex predators such as grizzly bears and gray wolves had been extirpated from their original ranges, but have partially recovered due to conservation measures and reintroduction. Other recovering species include the bald eagle and the peregrine falcon.