The Sevilleta LTER was initiated as the Sevilleta National Wildlife Refuge, a former Spanish land grant now administered by the U.S. Fish and Wildlife Service (FWS). The research area encompasses approximately 3,600 square kilometers and ranges from Rio Grande riparian forests (bosque) and Chihuahuan Desert up to subalpine forests and meadows. Because the Sevilleta LTER is a transition zone for a number of biomes, the area cannot be easily or conveniently characterized. This convergence of biomes, however, has created an important research area for geology, hydrology, archeology, atmospheric science, biology, and ecology for many decades.