The Last Desert Grasslands

Excerpts from a report by the Southwest Environmental Center. Read the full report on the SWEC website.

A unique landscape

Otero Mesa grasslands

Grasslands once blanketed much of the Chihuahuan Desert–a surprising fact given their general absence from the region today. Indeed, the grass was so luxuriant in some places that it was actually harvested commercially for hay. Most of these grasslands have disappeared, converted to desert scrub. Where they still exist, they have generally been reduced to small patches that vary in size from a few acres to a few hundred acres—too small to support the full range of wildlife once associated with these habitats. Otero Mesa is one of the few exceptions.

Located about 40 miles northeast of El Paso, the greater Otero Mesa ecosystem includes about 1.2 million acres in southern New Mexico. Most of it is gently undulating terrain between 4000 and 5600 feet, with a few isolated peaks rising to 7000 feet. The mesa is bounded on the north by the foothills of the Sacramento Mountains, by Crow Flats and the Guadalupe Mountains to the east, and by an escarpment that drops dramatically down to the Tularosa Basin on the west. The mesa gradually descends into the shrubland of west Texas to the south. The western portion of Otero Mesa extends onto the McGregor Range on Fort Bliss Military Reservation. The remainder of the area is a checkerboard of federal, state and private land. The dominant land use is ranching.

Roughly half of Otero Mesa is grassland, dominated by two drought resistant species—black grama (Bouteloua eriopoda) and blue grama (Bouteloua gracilis).1 The swales and valley bottoms are characterized by deeper soils and a cover of tobosa grass (Pleuraphis mutica) and burro grass (Scleropogon brevifolia). Soaptree yucca (Yucca elata) are the only tall plants, except for an occasional tree around a stock tank or ranch house. In contrast to much of west Texas and southern New Mexico, mesquite shrubs (Prosopis glandulosa) are virtually absent.

Otero Mesa’s grasslands are extraordinarily healthy and diverse. The area is home to at least 13 species of grasses, including some that are rare or found nowhere else in the region, such as New Mexico Stipa (Stipa neomexicana) and Hairy Grama (Bouteloua hirsuta).2 In ungrazed areas of Otero Mesa, grass cover as high as 42 percent has been measured. By comparison, rangelands considered to be in “good” condition elsewhere in the region typically have only six or seven species and 10 to 20 percent grass cover.

Looking east across Otero Mesa towards the Guadalupe Mountains.

In addition, the grasslands of Otero Mesa are relatively large and intact. There are no towns on the mesa, nor many roads other than lightly used dirt ranch roads. It is one of the last remaining large tracts of grassland remaining in the Chihuahuan Desert of North America. The lack of developments, the healthy grassland ecosystem, and the scarcity of shrubs make Otero Mesa a truly unique landscape. It is a window into the recent evolutionary past, still home to essentially the same assemblage of plant and animal species that existed when Coronado rode through the region 500 years ago, looking for the Seven Cities of Gold.