Montane Forests

Two large mountain ranges, the Sierra Nevada and the Rocky Mountains, dominate western North America. Significant differences arise between the vegetation developing on slopes with northern and southern exposures: the band representing each zone extends farther upward on south-facing slopes, whereas the same band dips downward on north-facing slopes where conditions are relatively cooler. A community dominated by ponderosa pine marks the lowest zone in the Montane Forest. Douglas fir represents the climax vegetation in the upper part of the Montane zone. Large, naturally treeless sites known as mountain parks are scattered throughout the forests of the Rocky Mountains. The Black Hills are a mountainous “blister” arising in isolation on the northern Great Plains, but geologists nonetheless consider the formation as part of the Rocky Mountains. In Montane forests, and in their huge range, red squirrels rely on large caches of cones for their winter food supply.