The Shortgrass Steppe (SGS) LTER project studies an ecosystem that has persisted under a regime of semi-arid extremes, with high inter- and intra-annual variability in precipitation and temperature. The 340 mm of annual precipitation falls primarily during spring rainstorms over several days as well as during a period of summer rains from more localized thunderstorms. Further, the system is well-adapted both to grazing by large herbivores and to smaller-scale disturbances caused by animals like prairie dogs. The shortgrass prairie ecosystem in Colorado currently exists as a mosaic of land use including native prairie, recovering prairie (some in the federal Crop Reserve Program (CRP)), rangeland, tilled and irrigated farmland, and urban and exurban development. Tillage for row-crops, especially under irrigation, provides the largest-scale disturbances on the SGS ecosystem. Our research focuses on three primary determinants: climate, disturbance and land use, and physiography.

Our research examines processes that may allow us to determine whether the system will continue to persist under global change, including alterations in timing and intensity of rainfall, habitat fragmentation caused by land use differences, and the possibility of invasion by exotic species. Because of complex interactions between determinants and the importance of belowground processes, we use soil moisture as a master variable that integrates the effects of determinants on the current state of the system and its potential to respond to global change. Additionally, the SGS LTER project addresses scientific initiatives important to our region, conducts synthetic modeling that includes the global scale, and is initiating new experiments to investigate potential responses to global change. We integrate our research across multiple scales of measurement from molecular analyses of soil microbial communities to landscape-scale remote sensing of soil moisture and annual net primary productivity.