Effects of substrate on dendrochronologic streamflow reconstruction: Paria River, Utah with fractal application to dendrochronology.

Abstract

Two piñon (Pinus edulus) tree-ring chronologies developed on each of three substrates (sandstone, shale, and alluvial fan deposits) in southern Utah for the period 1702 to 1997 demonstrate that geologic substrate affects dendrochronologic streamflow reconstructions. Chronologies from alluvial fan deposits explain the most variance of cool-season (October 1 to May 31) flow with an adjusted coefficient of determination (Rₐ²) equal to 0.59. Chronologies from sandstone deposits account for 52 percent of the variance, while those on shale deposits account for 45 percent. Correlation coefficients among the three substrates are significantly different at the 95% confidence level. The highest single-site annual discharge reconstruction (October 1 to September 30), Rₐ² = 0.25, is provided by chronologies from shale deposits. The highest substrate-pair annual discharge reconstruction, Rₐ² = 0.27, is provided by chronologies from alluvial fan deposits. The highest summer discharge reconstruction(July 4 to September 3), Rₐ² = 0.14, is provided by chronologies from sandstone. Over 90 percent of the summer reconstructions are below Rₐ² = 0.10.