APPLICATIONS OF TREE-RING SERIES WITHIN THE BEAR RIVER RANGE, NORTHERN UTAH TO RECONSTRUCT DROUGHT VARIABILITY

Population centers in semi-arid northern Utah are sensitive to drought due to their dependence on winter precipitation for water supply. However, relationships between precipitation and Pacific Ocean conditions such as the Pacific Decadal Oscillation and El Niño Southern Oscillation are complex in this region and limited by short instrumental records compared to decadal-scale climate variability. Tree-ring series collected from moisture sensitive sites can be used to extend precipitation and stream discharge records (Carson and Munroe, 2005; Knight et al., 2010). However, there are no published tree-ring reconstructions from the Bear River Range of northern Utah. The goals of this research are to 1) create an up to date tree-ring chronology using moisture sensitive Douglas fir trees and 2) use this chronology to reconstruct precipitation patterns in northern Utah. High elevation Douglas fir trees were sampled from rocky, south and west facing slopes on Mt. Naomi in the Bear River Range, Utah. The tree-ring widths were measured and standardized. These standardized values were compared to, and used to update, an existing tree-ring chronology created by Woodhouse (1989). Results indicate a correlation between these chronologies and sufficient sample depth to extend the combined chronologies back 700 years before present. Preliminary results relating these tree-ring data to precipitation, and potentially stream discharge, will be presented.