Arizona/New Mexico Mountains ecoregion

The Arizona/New Mexico Mountains ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency (EPA) in the U.S. states of Arizona and New Mexico, with a small extension into the Guadalupe Mountains in Texas.^[2] The World Wildlife Fund named this ecoregion Arizona Mountains forests, and classified it as a temperate coniferous forests ecoregion.^[3] The ecoregion has a rich variety of woodland habitats and wildlife.

Arizona/New Mexico Mountains ecoregion
Aspen forest below Humphreys Peak
The Arizona/New Mexico Mountains ecoregion (23)
Ecology
Realm	Nearctic
Biome	Temperate coniferous forests
Borders	Colorado Plateau shrublands Chihuahuan Desert Sonoran Desert
Bird species	208[1]
Mammal species	123[1]
Geography
Area	109,100 km2 (42,100 sq mi)
Country	United States
States	Arizona New Mexico Texas
Rivers	Gila River
Conservation
Habitat loss	0.307%[1]
Protected	73.78%[1]

Setting

The region is a transition region from the lower elevation Sonoran Desert (81) to the southwest and Chihuahuan Desert (24) southeast; the west is bordered by the mid-elevation Mojave Desert (14).

The north is bordered by the east–west Arizona/New Mexico Plateau (22), ecoregion which is part of and is the southern region of the Colorado Plateau. The north region of the Colorado Plateau covers eastern Utah/western Colorado and is the Colorado Plateaus (ecoregion) (20). The extreme southern perimeter of the Colorado Plateaus ecoregion extends east–west along the border regions of Arizona-New Mexico.

The ecoregion landscape of steep mountains and high stony plateaus with rocky outcrops from the Kaibab Plateau in northern Arizona south to the Mogollon Plateau, extending eastwards into southwestern New Mexico and into the Trans-Pecos region of West Texas. Elevations range from 1,370 to 3,000 meters (4,490 to 9,840 ft), with some peaks higher than that. Specific areas include the Gila Wilderness in New Mexico. ^[3]

Subregions

Chihuahuan Desert Slopes (23a)

The Chihuahuan Desert Slopes are found on the Guadalupe and Sacramento Mountains. The lower slopes of these mountains represent a continuation of the Chihuahuan Desert ecosystem; soils and vegetation in much of ecoregion 23a are similar to those in the low mountains and bajadas of the Chihuahuan Deserts. The lower slopes were once mostly grasslands overgrazed in the late 19th century and subsequently invaded by desert shrubs. Yucca, sotol, lechuguilla, ocotillo, and cacti now dominate the rocky slopes below 5,500 feet (1,700 m). Grasslands persist near alluvial fans and on gentle slopes with deeper, sandstone-derived soils. Water is scarce; the few streams that originate from springs at higher elevations do not persist beyond the mouths of major canyons.^[4]

Madrean Lower Montane Woodlands (23b)

Juniperus deppeana in the Mogollon Mountains

The Madrean Lower Montane Woodlands ecoregion covers the slopes of the Guadalupe, Sacramento, Mimbres, Big Burro, and Mogollon Mountains, extending into the Mogollon Transition in Arizona. The ecoregion generally lies between 5,500 to 7,200 feet (1,700 to 2,200 m) in New Mexico and 4,200 to 7,000 feet (1,300 to 2,100 m) in Arizona, with densities of juniper, pinyon pine, and oak varying according to aspect. There are some similarities to ecoregion 23e; however, this has milder winters, wetter summers, and inclusions of alligator juniper and Madrean evergreen oak species, such as Gray and Emory oak. At middle elevations, dense thickets of shrubs such as desert ceanothus, alderleaf mountain mahogany, turbinella oak, manzanitas, and catclaw mimosa form chaparral communities. Other areas are grassy and park-like with mixed gramas and scattered trees. A few small areas of ponderosa pine, Douglas-fir, or southwestern white pine occur at the highest elevations, outliers of ecoregions 23c or 23f. In the west, the Gila River and tributaries have many endemic aquatic organisms including fish, amphibians, and insects.^[4][5]

Montane Conifer Forests (23c)

The Montane Conifer Forests are found west of the Rio Grande at elevations from about 7,000 to 9,500 feet (2,100 to 2,900 m). Ponderosa pine and Gambel oak are common, along with mountain mahogany and serviceberry. Some Douglas-fir, southwestern white pine, and white fir occur in a few areas. Blue spruce may occasionally be found in cool, moist canyons. The influence of the Sierra Madre flora is seen mostly in the southern mountains and diminishes to the north. In the far south, other oaks appear, such as silverleaf oak, netleaf oak, Arizona white oak, and Emory oak. The summer rains are especially important for herbaceous plants. The region is geologically diverse with volcanic, sedimentary, and some intrusive and crystalline rocks. Endemic Gila trout occur in some of the region’s streams. Livestock grazing, logging, and recreation are the primary land uses. Wildfire is an important feature influencing the forested ecosystems in this region.^[4]

Arizona/New Mexico Subalpine Forests (23d)

Subalpine forest at 10,000 feet (3,000 m) on slopes of Mount Taylor

The Arizona/New Mexico Subalpine Forests occur west of the Rio Grande at the higher elevations, generally above 9,500 feet (2,900 m). The region includes parts of the Mogollon Mountains, Black Range, San Mateo Mountains, Magdalena Mountains, and Mount Taylor. The peak elevations are mostly above 10,000 feet (3,000 m). Although there are some vegetational differences from mountain range to mountain range within this ecoregion, the major forest trees include Engelmann spruce, corkbark fir, blue spruce, white fir, and aspen. Some Douglas-fir occurs at lower elevations. The ecoregion has a mixed geology of mostly Tertiary volcanics and intrusives, with only minor areas of Precambrian rocks in the Black Range.^[4]

Conifer Woodlands and Savannas (23e)

The Conifer Woodlands and Savannas ecoregion is an area of mostly pinyon-juniper woodlands, with some ponderosa pine at higher elevations. It often intermingles with grasslands and shrublands. Although elevations are higher than surrounding ecoregion 22 areas, the boundaries tend to be transitional. The region is generally cooler, with more uniform winter and summer seasonal moisture compared to ecoregion 23b. It lacks the milder winters, wetter summers, chaparral, Madrean oaks, and other species of ecoregion 23b.^[4]

Rocky Mountain Conifer Forests (23f)

The Rocky Mountain Conifer Forests are found at elevations from about 7,000 to 9,600 feet (2,100 to 2,900 m) in the mountains east of the Rio Grande. Similar to Ecoregion 23c, ponderosa pine and Gambel oak are common, with mountain mahogany and a dense understory. Some Douglas-fir, southwestern white pine, and white fir occur in a few areas. Blue spruce may occasionally be found in cool, moist canyons. In the Sandia and Manzano Mountains, white fir and Douglas-fir are more extensive than in other parts of the region. Current forests have been shaped by fire and fire suppression. It differs from Ecoregion 23c by some of the flora, fauna, and water quality characteristics that more closely resemble the Southern Rockies. The region is geologically diverse with volcanic, sedimentary, and some intrusive and crystalline rocks.^[4]

Flora

Trees of higher elevations of the area include Ponderosa pine, Blue spruce, Engelmann spruce, White fir, Rocky Mountain Douglas-fir, and Quaking aspen. The lower elevations have a mixed woodland with species such as Alligator juniper, Single-leaf pinyon, Colorado pinyon, Gambel oak, Emory oak, and Arizona white oak. Finally the rivers and their banks are important habitats for specific wildlife and fish.

Fauna

Wildlife found here include the miniature northern saw-whet owl and many birds and reptiles that are common in Mexico further south, such as the secretive Montezuma quail. The caves of the Guadalupe Mountains are a specific habitat for beetles, centipedes and other invertebrates.

Threats and preservation

This is a fairly stable ecoregion with about 25% of original habitat still intact although vulnerable to logging and overgrazing. Pollution and reduction of rivers are threatening specific plants and animals including Fremont cottonwood (Populus fremontii) and Goodding's willow (Salix gooddingii), the threatened Gila trout (Oncorhynchus gilae), and the endangered southwestern willow flycatcher (Empidonax traillii extimus). Logging continues to remove habitat of the Mexican spotted owl (Strix occidentalis lucida) and the northern goshawk (Accipiter gentalis).

Large blocks of remaining habitat include: the Aldo Leopold Wilderness/Gila Wilderness/Blue Range Wilderness and the El Malpais National Monument and Conservation Area in southwestern New Mexico; the Kaibab National Forest, Blue Range Primitive Area, Grand Canyon National Park, the Mazatzal Mountains including Four Peaks, Superstition Mountains, Sycamore Canyon, Red Rock-Secret Mountain Wilderness, Hellsgate Wilderness, Pinal Mountains in the Tonto National Forest and the Galiuro Mountains in Arizona; the Chuska Mountains on Navajo lands; and the Guadalupe Mountains including the Carlsbad Caverns in southeastern New Mexico and western Texas. Much of this is linked and well-protected within national parkland.^[3]

See also

• List of mountain ranges of Arizona
• List of mountain ranges of New Mexico
• Ecoregions defined by the EPA and the Commission for Environmental Cooperation:
  • List of ecoregions in North America (CEC)
  • List of ecoregions in the United States (EPA)
• The conservation group World Wildlife Fund maintains an alternate classification system:
  • List of ecoregions (WWF)
  • List of ecoregions in the United States (WWF)