22 – Arizona/New Mexico Mountains (4 – level 4 ecoregions)
“The Arizona/New Mexico Plateau represents a large transitional region between the drier shrublands and wooded higher relief tablelands of the Colorado Plateaus (20) in the north, the lower, hotter, less vegetated Mojave Basin and Range (14) in the west, and the semiarid grasslands of the Southwestern Tablelands (26) to the east. Higher, forest-covered mountainous ecoregions border the region on the northeast (21) and south (23). Local relief in the region varies from a few feet on plains and mesa tops to well over 1000 feet along tableland side slopes. The region extends across northern Arizona, northwestern New Mexico, and into the San Luis Valley of Colorado. Gunnison prairie dogs are a keystone species in many of the sagebrush ecosystems and their burrows provide habitat for other wildlife including burrowing owls, weasels, badgers, and a variety of snakes. (USGS, 2006; US EPA, 2013)”
22a – San Luis shrublands and hills
• Topography - The San Luis Shrublands and Hills ecoregion includes the higher relief foothill edges and low mountain areas within the basin. It includes the San Luis Hills in the southwest, a rugged mass of hills and tilted mesas. The hills are composed of andesitic volcanic rock and are 500 to 1000 feet higher than the adjacent ecoregions of 22.
• Land Use -
• Soils -
• Vegetation - Vegetation communities represent a transition from the grassland and desert communities of the lower basin to the woodland species found in the surrounding foothills of the Southern Rockies (21). Big sagebrush, rabbitbrush, and winterfat occur, as well as grasslands of western wheatgrass, green needlegrass, blue grama, and needle-and-thread. Areas of pinyon-juniper are found on the tops of the San Luis Hills.
• Other –
Sites to Visit - Culebra Creek, Del Norte, Rt285/17, Saguache Creek, San Acacia, Villa Grove
22b – San Luis alluvial flats and wetlands
• Topography -
• Land Use - Irrigated cropland is common, with barley malt, potatoes, alfalfa, small grains, and hay, and smaller areas of vegetables such as spinach, head lettuce, and carrots.
• Soils -enerally, the soils of this region tend to be less alkaline than the soils of 22c.
• Vegetation - The ecoregion was once dominated by shadscale, saltbush and greasewood, but most of the native vegetation has been removed for agriculture.
• Other - Although precipitation in the San Luis Alluvial Flats and Wetlands ecoregion is low, less than 8 to 10 inches, water availability from mountain runoff, a high water table, and associated springs and wetlands have made cropland irrigation possible. The increasing demand for water throughout this region is an ongoing issue, exacerbated by recent droughts. Increased salt accumulation in soils and groundwater depletion are problems associated with irrigation and the competing uses of available water.
Sites to Visit - Monte Vista National Wildlife Refuge, Rio Grande State Wildlife Area, Sanchez Reservoir
22c – Salt flats
• Topography - The Salt Flats ecoregion includes the alkaline basin that surrounds the San Luis Lakes. The smooth to irregular plains of low to moderate relief have elevations ranging from 7400 to 7700 feet, some of the lowest areas in the San Luis Valley.
• Land Use - Land use is limited to low density livestock grazing and wildlife habitat. Unlike 22b, cropland is more limited within this region due to the more alkaline soils.
• Soils -
• Vegetation - Vegetation is sparse, with greasewood and shadscale dominating along with scattered areas of horsebrush, spiny hopsage, rabbitbrush, saltgrass, alkali sacaton, and small areas of sagebrush at the eastern edges. Some areas are devoid of vegetation.
• Other - Precipitation ranges from 6 to 8 inches annually.
Sites to Visit - Alamosa National Wildlife Refuge, Blanca Wildlife Habitat Area, Russell Lakes, San Luis Lake State Park
22e – Sand dunes and sand sheets
• Topography - Great Sand Dunes National Park and the outlying sand sheets are included in the Sand Dunes and Sand Sheets ecoregion.
• Land Use - Land use in the region is mostly recreation and wildlife habitat, with some limited rangeland.
• Soils - The Great Sand Dunes rise up to 750 feet above the basin and are the tallest dunes in North America. The sand was derived mainly from volcanic rock sediments of the San Juan Mountains that were transported by the Rio Grande, and deposited on the alluvial fan on the west side of the valley. The sand was then blown by the prevailing southwesterly winds, piling up at the base of the mountains.
• Vegetation - The sand sheets consist of low parabolic and longitudinal dunes that are largely stabilized by scrubby vegetation. The dunes are mostly bare, with patches of Indian ricegrass, blowout grass, or lemon scurfpea. Sand sheet plants include rabbitbrush, sand dropseed, spiny hopsage, sand verbena, and prairie sunflower.
• Other –
Sites to Visit - Great Sand Dunes National Park