The field site is located south of the rapidly developing Salt Lake City area, also near Provo and Logan, anchoring this arid urban-rural megatransect.
Site history & management
The Onaqui-Benmore area has been grazed by domestic livestock since settlement. By the 1980's, the U.S. Forest Service instituted a light to moderate fall and winter grazing regime that continues today.Fire has always been a component of sagebrush steppe, one of the dominant vegetation types in the area. However, the invasions of exotic annual vegetation, especially Bromus tectorum, also known as drooping brome or cheatgrass, have dramatically shortened fire return intervals. The invasion-fire feedback has resulted in the loss of native perennial species from extensive areas of the region. The restoration of sagebrush at Onaqui-Ault after the cheatgrass invasion and woodland expansion creates an opportunity to collect data on the changes related to invasive or non-invasive species advancement, as well as the dynamics of rodents and hantavirus.
Onaqui is located in the Intermountain Region, between the Sierra Nevada and Cascade ranges in the West and the Rocky Mountains to the east, which is among the driest regions of the U.S. In winter, western North American climate is dominated by a westerly flow of cool, moist air from the northern Pacific. The Sierras and Cascades cast a rain shadow across the Intermountain Region, leading to low precipitation in the basins. Monsoonal flow from the subtropical eastern Pacific becomes more important in the summer, but most of the Intermountain Region is currently beyond the monsoon's typical northern limits. In the Intermountain West, dust resulting from urban and agricultural land use change is transported over long distances. When deposited on the mountain snowpack, it alters the snow albedo, affecting snowmelt timing, seasonal hydroperiods, and alters local land surface feedbacks to climate. Sites in the Great Basin (D15) and Central Rockies-Colorado Plateau (D10, D13) are located to examine these effects of dust.
Dominant vegetation at Onaqui is characterized by sagebrush and western juniper. In particular, the tower site is an area of extensive sagebrush steppe (Artemisia tridentata) transitioning into juniper woodland. In general, this domain is broadly characterized by combinations of lower-elevation, sagebrush steppe and higher-elevation montane forests. This complex topography impacts climate, hydrology, and species distributions, with montane zones exerting a disproportionate influence.