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Date of Award
Master of Science (MS)
Bunn, Andrew Godard
Matthews, Robin A., 1952-
Salzer, Matthew W.
Tree-ring analysis can provide information about the surrounding environment of trees, as ring widths often reflect the variability of the factors that limit their growth. Great Basin bristlecone pine (Pinus longaeva D. K. Bailey) provides crucial tree-ring data to understand paleoclimate, but the growth signals can be difficult to interpret. The bristle- cone record could present a potentially confounding narrative because of its mixed growth signals; in many cases, not all trees at one site are limited by the same environmental variable. Trees that are sensitive to patterns in temperature tend to grow in the alpine upper treeline ecotone, and trees limited by moisture availability have the tendency to grow downslope. At four sites in the Great Basin region, USA, this study uses cluster analysis to find dual-signal patterns in tree growth, and uses topoclimate modeling to better understand bristlecone growth. I found two-cluster patterns at two of those sites; both of these sites included a cluster that correlated well with temperature data and one cluster that correlated with reconstructed drought data. Temperature-limited clusters contained trees growing in colder areas at higher elevations, and moisture-limited clusters contained trees at lower elevation in warmer areas. This study presents models to predict the primary limiting factor of an individual tree based on topoclimate variables in hopes of furthering understanding of mixed-signal growth patterns and improving the accuracy of climate reconstructions using bristlecone pine.
Western Washington University
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Tran, Tyler J., "Cluster Analysis as a Means of Examining Topographically-mediated Bristlecone Pine (Pinus longaeva) Growth in the American Southwest" (2016). WWU Graduate School Collection. 487.