The Sevilleta (SEV) Long Term Ecological Research Site: Drivers of Variability in Drylands

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The Sevilleta (SEV) Long Term Ecological Research Program, (SEV), established in 1988, advances scientific knowledge to inform the conservation and management of dryland ecosystems. Drylands constitute the world’s largest terrestrial biome and have increasingly been recognized for their substantial contributions to global biogeochemical cycling and global change. Recent work revealed that semiarid ecosystems control year-to-year variation in the carbon sink strength of the global terrestrial biosphere. Despite their prominence, drylands feature as one of the least understood of the major biomes.

At the heart of the SEV is the 3,600 km² Sevilleta National Wildlife Refuge, positioned at the confluence of five quintessential dryland biomes: Chihuahuan Desert grassland and shrubland to the south, Great Plains grassland to the north, conifer-dominated woodlands in the upper elevations, Colorado Plateau shrub-steppe to the west, and a riparian corridor along the middle Rio Grande Valley. These biomes are characterized by high spatio-temporal variability in population, community, and ecosystem dynamics. Thus, current research is guided by the question: how do abiotic drivers affect the variability of dryland populations, communities and ecosystems? Long-term observations assess the relative importance of alternative abiotic drivers of biotic variation, stability, and resilience. Companion experiments isolate single and factorial abiotic mechanisms. Our long-term observational and experimental research has yielded a new conceptual model for plant-microbe interactions (the fungal loop hypothesis) as well as a novel hierarchical, multi-scale model of aridland pulse dynamics. Together, these research approaches confront and integrate the primary global change stressors for drylands: precipitation amount and variability, fire, nitrogen deposition, and warming temperatures. Broader impacts include intensive, research-centered learning through our undergraduate REU site program and K-12 Schoolyard LTER Bosque Ecosystem Monitoring Program (BEMP), professional training in collaboration with the Geographic Information Technology and Natural Resources Programs at the Southwest Indian Polytechnic Institute (SIPI), mentoring partnerships with ESA SEEDS, and public outreach programs through the National Wildlife Refuge.