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Species Sensitivity to Hydrologic Whiplash in The Tree-Ring Record of the High Sierra Nevada
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  • Anabel Winitsky,
  • David Meko,
  • Alan Taylor,
  • Franco Biondi
Anabel Winitsky
University of Arizona

Corresponding Author:winitsky@arizona.edu

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David Meko
University of Arizona
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Alan Taylor
Pennsylvania State University Main Campus
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Franco Biondi
University of Nevada Reno
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Abstract

Year-to-year variability of precipitation and temperature has significant consequences for water management decision making. “Whiplash” is a term which describes this variability at its most severe, referring to events at various timescales in which the hydroclimate switches between extremes. Tree-rings in semi-arid environments like the Truckee-Carson River Basin (California/Nevada watersheds with headwaters in the Sierra Nevada) can provide proxy records of hydroclimate as their annual growth is tied directly to limitations in water-year rainfall and temperature, but traditional metrics of reporting explained variance do not distinguish a reconstruction’s sensitivity to whiplash events. In this study, a pool of total ring width indices from five snow-adapted conifer species (Abies magnifica, Juniperus occidentalis, Pinus ponderosa, Pinus jeffreyi, Tsuga mertensiana) were used to develop a series of standardized reconstructions of water-year PRISM precipitation (P12) using stepwise linear regression. A nonparametric analysis approach was then used to determine positive and negative whiplash events in reconstructed and instrumental precipitation records. Hypergeometric distribution of the resulting timeseries datasets illustrates relationships between reconstructions and recorded whiplash events and allows for determination of patterns in tree-ring growth response. The results of this study suggest that ring-width indices from the assessed conifer species in the snow-belt of the Sierra Nevada are often able to record consecutive years of opposing extreme precipitation and report such events through derived models. Negative WL events are tracked more consistently across species in site-specific reconstructions of P12 than positive ones. It appears that residual effects of a preceding year’s drought or pluvial do not necessarily suppress records of WL, though sensitivity to precursor conditions in tracking of WL events may differ across species, and the absolute WL events captured in a reconstruction vary.