page_title: Ecology of the Rocky Mountains
section_title: Treeline vegetation
hierarchical_section_title: Ecology of the Rocky Mountains / Biotic zones / Treeline vegetation
caption_attribution_description: Abies lasiocarpa English: Subalpine fir twisted by wind and weather (en:Krummholz). Glacier National Park, Montana, US.
context_page_description: The ecology of the Rocky Mountains is diverse due to the effects of a variety of environmental factors. The Rocky Mountains are the major mountain range in western North America, running from the far north of British Columbia in Canada to New Mexico in the southwestern United States, climbing from the Great Plains at or below 1,800 feet to peaks of over 14,000 feet. Temperature and rainfall varies greatly also and thus the Rockies are home to a mixture of habitats including the alpine, subalpine and boreal habitats of the Northern Rocky Mountains in British Columbia and Alberta, the coniferous forests of Montana and Idaho, the wetlands and prairie where the Rockies meet the plains, a different mix of conifers on the Yellowstone Plateau in Wyoming and in the high Rockies of Colorado and New Mexico, and finally the alpine tundra of the highest elevations.
context_section_description: Treeline is the elevation above which trees cannot grow. It is controlled by a complex of environmental conditions, primarily soil temperatures and the length of the growing season—which becomes shorter with higher elevations. The elevation of treeline rises steadily at the rate of 100 metres (330 ft) per degree of latitude from the northern to the southern Rocky Mountains. Dominant treeline species, including spruces, firs, and white pines, often have a shrublike form in response to the extreme conditions at the elevational limits of their physiological tolerance; such dwarfed trees are called krummholz. Krummholz islands may actually move about 2 centimeters per year in response to the wind; they reproduce by vegetative layering on their lee sides, while dying back from wind damage on their windward sides. Under favorable climatic conditions, krummholz can assume an upright treelike form or can increase their cone crops and seedling establishment.
caption: A subalpine fir near treeline in Glacier National Park, twisted into an unusual shape
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