Conservation at a larger scale: The Arizona / New Mexico Mountains Ecoregion
By New Mexico Staff

It is a natural trait of human beings to try to organize and classify their complex world into categories; shoeboxes, if you will, for storing information. Because of this, we tend to view the universe as being made up of a number of "things." But a broader examination reveals that the cosmos is really composed of "processes." From nuclear fusion to evolution, from volcanism to digestion, and from rivers to sand dunes, the universe is a bewildering array of ongoing, ever-changing, dynamic processes.

This makes our business, that of conserving biodiversity, seem a little more challenging. You can't study natural processes for very long without realizing that everything is, indeed, connected. Nevertheless, viewing the world through the "big lens" of processes helps us do our conservation work more carefully, more efficiently, and more effectively. On the ground, that means looking beyond individual species and natural communities, and beyond our artificial state and international boundaries, to the level of the landscape.

The best science tells us that the best way to view biodiversity, and the processes that shape it, on the landscape is at the level of the ecoregion -- distinct, typically vast areas that are defined by unique combinations of plants, animals, soils, climate, landforms, and geology. Because they are defined by similar ecological boundaries, they provide more relevant geographic units for conservation than political boundaries. Seven ecoregions converge to make the varied landscape we know of as New Mexico: the Colorado Plateau, Colorado Rocky Mountains, Chihuahuan Desert, Central Shortgrass Prairie, Apache Highlands, Southern Shortgrass Prairie, and the Arizona / New Mexico Mountains. Click here to view a map of the ecoregions of the southwestern United States.

The Arizona / New Mexico Mountains Ecoregion encompasses the highlands of eastern Arizona and western and central New Mexico. These are the oldest mountains in the southwest, containing Precambrian igneous rocks as old as 1.5 Billion years. These older volcanics are overlain with more recent sediments (including important fossil deposits from the Jurassic and Triassic) and newer volcanics (including volcanic flows and caulderas from as recently as 1,000 years ago). The result is an extremely diverse physiographic region with elevations ranging from about 5,000 to more than 10,000 feet above sea level. One of the most prominent features of the region is the Mogollon (Mug-ee-yawn) Rim, which stretches more than 300 miles from Silver City, NM to near Flagstaff, AZ. The rim defines the southern edge of much of the ecoregion.

The Arizona-New Mexico Mountains are 30 million elevated acres that belie the parched stereotype of the desert southwest. The mountains contain the headwaters for a number of important streams and rivers including the Little Colorado, the Gila, the Mimbres, and the Verde. Ecologically, the ecoregion is an area of big trees. The single feature that best characterizes the region is ponderosa pine forest; historically the plateau along the Mogollon Rim was an unbroken, majestic stand of ponderosa pine from the base of the San Francisco Peaks to the White Mountains. Extending into New Mexico, the region becomes more broken and rugged, but ponderosa pine forest remains one of its most ubiquitous habitats. At lower elevations, ponderosa pine forest gives way to more open woodlands of pinyon pine and juniper and, at higher, cooler sites, dense stands of mixed coniferous forest prevail-including Douglas fir, white fir, spruce and aspen. At the highest elevations are found the most southerly examples of alpine tundra on the continent.

The ecoregion is one of the ecological treasure-troves of the United States, containing more species of birds and mammals than any other place in the southwest. This landscape is home to more than 100 rare plants and animals, more than 25 of them listed as endangered or threatened by the federal or state governments. Of special concern are some of the most critically imperiled aquatic species in these two states, including the Gila chub, the Chihuahua chub , the Gila trout, the Apache trout, the roundtail chub, the loach minnow, the spikedace, and the Chiricahua leopard frog.

The rugged landscape is subject to the large-scale processes of fire and flood. Winter snows and summer "monsoon" rains feed the river systems. These processes are critically imperiled through long histories of fire suppression, poorly-managed livestock grazing, and stream channelization.

The Nature Conservancy has been involved in projects in the ecoregion for many years, including the Gila River and Mimbres River preserves, the Rio Nutria Preserve, and Sevilleta National Wildlife Refuge in New Mexico, and Hart Prairie in Arizona. However, much of the land in the ecoregion is under federal ownership, especially the U.S. Forest Service. Also included with the boundaries are portions of the nations of the White Mountain Apaches, the Mescalero Apaches, the Navajos, and the Zunis. Successful conservation work here, especially, entails working closely with these and other land management partners.