Recent drought and increasing demands on the water supply emphasize the need to account for climate variability in all aspects of natural resource management. In particular, moisture variability can influence fire occurrence, habitat quality and wildlife distributions. Tree-rings provide a window into past precipitation regimes, yielding critical information on trends in water resources. In 2006 the Teton Research Institute of Teton Science Schools partnered with the University of Arizona - Laboratory of Tree Ring Research to develop a reconstruction of historic streamflows in the Upper Snake River Watershed (USRW). The reconstruction provides a much-needed understanding of historic precipitation patterns in the region. We sampled Douglas fir (Pseudotsuga menziesii) and limber pine (Pinus flexilis) at 5 sites in the Greater Yellowstone Ecosystem. Tree cores and cross-sections from each site were used to develop a proxy for annual precipitation that spans 1125 – 2006 A.D. Our data suggest that the 20th century is probably the wettest this region experienced in a few hundred years. The average flow over the past 100 years is higher than any other average flow estimated from the previous three centuries. Prolonged dry periods are a natural part of the climate regime in this area. Dry-cycles that are longer and more severe than 20th century droughts are likely to occur in the future.

The USRW provides the headwaters for the Snake River, one of the most heavily used rivers in the West. Results from this study will help resource managers better understand natural precipitation variation in the USRW and will facilitate sustainable resource management practices that consider a range of possible climatic conditions. The efficacy of future wildlife management efforts largely depends on changing climate conditions and the underlying natural precipitation variability.

Project Goals


* Data analysis courtesy of University of Arizona - Laboratory of Tree Ring Research

Publications and Presentations

"Tree Rings Indicate Climate Could Get Drier"
Jackson Hole News and Guide, March 18, 2009. (PDF format 293 KB)

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