Montane Forests of the Southwest

The American Southwest is often imagined as a dry landscape dominated by vast deserts, with only major urban areas such as Phoenix, Tucson, and Albuquerque standing out among the surrounding wilderness. While this perception is partly accurate, the region also contains cooler and wetter environments found at higher elevations, including mountain ranges and elevated plateaus.

Introduction

High-elevation landscapes in the Southwest support montane forests and even snow-covered alpine tundra, such as those found on the San Francisco Peaks in northern Arizona.

These mountain environments contain forests made up of species such as pine trees (Pinus spp.), Douglas-fir (Pseudotsuga menziesii), firs (Abies spp.), spruces (Picea spp.), and quaking aspens (Populus tremuloides). These tree species are more commonly linked with northern Rocky Mountain states like Colorado, Wyoming, and Montana. Beyond forests, these elevated regions also include grasslands, shrub-covered areas, and alpine tundra near the highest summits.

Although montane forests account for only about 8% of the combined land area of Arizona and New Mexico, they play an essential role in the region. From an ecological perspective, they contribute greatly to the Southwest’s remarkable biodiversity by creating specialized habitats within an otherwise dry environment. From an economic standpoint, these forests have long provided valuable resources, including timber, grazing areas, and water supplies. They also support outdoor recreation and tourism while offering some of the most breathtaking scenery in the Southwest.

Distribution of Montane Forests

Montane forests in the American Southwest occur only in high-elevation mountains and plateaus, which results in a scattered and fragmented distribution. Some regions contain large continuous forest areas, including the southern extension of the Rocky Mountains in northern New Mexico and a broad forest belt stretching from west-central New Mexico toward Flagstaff, Arizona.

Other montane forests appear as smaller isolated areas scattered across the desert landscape. Examples include the Santa Catalina and Pinaleño Mountains in southern Arizona and the Animas Mountains in southwestern New Mexico. These isolated high-elevation regions are often called “sky islands” because they rise above the surrounding desert like separate ecological islands.

The easternmost example of montane forest in the Southwest is located in the Guadalupe Mountains of western Texas and nearby parts of New Mexico.

Climate Change and Species Movement

The plant species that make up modern montane forests have experienced many shifts in distribution throughout history as climate conditions changed. Because mountain environments allow species to move relatively short distances up or down slopes, montane plants were often able to adapt more easily to periods of warming or cooling.

Lowland species faced greater challenges because they often needed to travel much farther north or south to find suitable conditions, sometimes crossing areas with unsuitable environments. As a result, mountain regions acted as safe havens for species threatened by climate changes and also served as starting points for species expansion when conditions became favorable.

Research by paleoecologists has shown that species did not always move together as complete ecosystems or communities. Instead, individual species migrated independently over time. Because of this, ancient montane forests were often made up of different combinations of plants compared with the forests found in the Southwest today.