The assessment area, referred to in this REA as the Central Yukon (CYR) study area, includes a core of seven ecoregions selected by BLM: Brooks Range (south of the ridge crest), Davidson Mountains, Kobuk Ridges and Valleys, North Ogilvie Mountains, Ray Mountains, Yukon–Old Crow Basin, and Yukon-Tanana Uplands. Ecoregions in this assessment were defined by Nowacki et al. (2001) and represent a unified mapping approach that blends traditional approaches with regionally-specific knowledge and ecological goals. Following BLM guidelines, the study area was formed by buffering the selected ecoregions by any 5th-level hydrologic units that intersected the ecoregion boundaries. Additionally, at the request of the BLM, the assessment boundary includes key lands surrounding the Dalton Highway on the north edge of the study area. Most of the Kotzebue Sound Lowlands are included in the study area because of the buffer region. The buffer region additionally causes the inclusion of small portions of several ecoregions along the southern boundary of the study area: these portions have been modified into a conglomerate unique to this REA referred to as the Tanana-Kuskokwim-Yukon Lowlands.
This region has a boreal climate, with long cold winters and relatively brief but warm summers. Climate varies depending primarily upon elevation, proximity to the coast, and latitude. Although in general the most extreme cold occurs at high elevations, some areas experience localized temperature inversions. With mean annual temperatures below freezing in most areas, but above freezing in others, permafrost is discontinuous. This discontinuity occurs at both fine scales and broader scales.
The Final Report contains the detailed results from the Central Yukon Rapid Ecoregional Assessment. The Central Yukon REA does not include a Manager's Summary document.