The Cerro Montosa Pinyon-Juniper site has been the location of major Sevilleta LTER research since 1989. Meteorological trends, net primary productivity, rodent and ground-dwelling arthropod populations, mycorrhizal responses to fertilizer, pinyon-juniper fruit and nut production, and pinyon mortality are all being investigated at this site. Previous studies have included analyses of pinyon tree rings for regional climate reconstruction.
The vegetation is New Mexico Pinyon-Juniper Woodland, dominated by Colorado pinyon (Pinus edulis) and one-seed juniper (Juniperus monosperma), and accompanied by gray oak (Quercus grisea). There is a diverse shrub component, including scrub live oak (Q. turbinella), mountain mahogany (Cercocarpus montanus), broom snakeweed (Gutierrezia sarothrae), sacahuista (Nolina microcarpa), red barberry (Mahonia haematocarpa), Apache plume (Fallugia paradoxa), tree cholla (Opuntia imbricata), skunkbush (Rhus trilobata), and banana yucca (Yucca baccata). Grass diversity is also high, and open spaces between trees are dominated by blue grama (Bouteloua gracilis), with hairy and sideoats grama (B. hirsuta and B. curtipendula) and black grama (B. eriopoda) also being significant. Other common grasses include purple threeawn (Aristida purpurea), wolftail (Lycurus phleoides), mountain and ring muhly (M. montanus and M. torreyi), and New Mexican porcupinegrass (Heterostipa neomexicana). Common forbs include small-flowered milkvetch (Astragalus nuttallianus), white sagebrush (Artemesia ludoviciana), Fendler’s arabis (Arabis fendleri), Fendler’s sandmat (Chamaesyce fendleri), New Mexico thistle (Cirsium neomexicanum), false pennyroyal (Hedeoma oblongifolia), bastard sage (Eriogonum wrightii), pingüe rubberweed (Hymenoxys richardsonii), large four o’clock (Mirabilis multiflora), Fendler's penstemon (Penstemon fendleri), and globemallows (Sphaeralcea hastulata and S. wrightii).