The Island Research Natural Area Prineville District , BLM Blue Mountains, Oregon Ecoregion Cell(s): Western juniper/big sagebrush-bitterbrush/bluebunch wheatgrass and Idaho fescue

Access is tightly controlled. Permission and permits from the Prineville BLM office are required. Paved roads lead to a parking area near the RNA, and a steep, undeveloped, rocky trail leads up to the plateau.

The Island is a basalt plateau at the confluence of the Crooked and Deschutes Rivers located near Madras, Jefferson County, Oregon. At 730 m, the 81 ha RNA is isolated from the surrounding topography of alternating ash beds, gravels, and basalt lava flows by steep cliffs. Soils in the RNA include Degner gravelly loam and Era loam. The cool desert climate has an estimated 26 cm of annual precipitation (Madras weather station). The plant community on the plateau is primarily big sagebrush/bluebunch wheatgrass (Artemisia tridentata/Pseudoroegneria spicata) with Idaho fescue (Festuca idahoensis) and antelope bitterbrush (Purshia tridentata). Western juniper (Juniperus occidentalis) is scattered or clumped throughout. This RNA, managed jointly by the BLM and Forest Service, was selected for its pristine botanical plant community that was briefly grazed only once, in the 1920s. Periodic lightning-caused fires are a normal occurrence, generally burning only small areas. The area was popular for recreational hiking until closed to the general public in 1997. Noxious weeds, especially medusahead (Taeniatherum caput-medusae), are a concern. Numerous permanent plots have been established, including plant community studies (beginning early 1960s to present), a BLM reference area, bitterbrush research, microbiotic crust studies, and USFS forest inventory plots. Additionally, there have been investigations into carbon dioxide enrichment of the atmosphere and dendrochronological work with western juniper. In 2004, a description of the RNA was published in Kalmiopsis, the journal of the Native Plant Society of Oregon.