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Use of wood-anatomical variables of bur oak (Quercus macrocarpa) in the reconstruction of climate
Abstract
A variety of wood-anatomical variables in a ring-porous oak (bur oak, Quercus macrocarpa Michx.) growing in southeastern Nebraska exhibit sensitivity to yearly variations in climate. Factor analysis of these variables reveals the existence of independent sources of variance that can be related to conductivity and vulnerability to water stress. The early and late woods vary in their response to climate, with vessel diameter being related negatively to precipitation in the spring wood and positively in the summer wood. The variables also exhibit sensitivity to temperature during the winter half-year. Ring width varies with summerwood characteristics and exhibits precipitation sensitivity somewhat less than summerwood vessel diameter, results that were found to hold in several other ring-porous species; the precipitation sensitivity of ring width appears to be indirect, being related to the positive association between precipitation and summerwood vessel diameter. Three variables-- summerwood vessel diameter, springwood vessel diameter, and diameter of the largest springwood vessel--are representative of the three axes of variance among the variables and were incorporated into climate-reconstruction models. Multiple-regression models for precipitation October-May, total snow, and heating degree days were developed and tested. Equations incorporating the three diameter-related variables gave unsuccessful results when tested against independent climatic data. Equations for precipitation October-June incorporating summerwood vessel diameter only were successful in reproducing the independent data set (r =.87, p =.001). Vessel diameter of the summer wood thus holds most promise for future reconstruction work. Occurrence of trees with ring-porous wood is related to limiting climatic factors; percentages increase with decreasing precipitation and fall off in the poleward direction where winter temperature extremes become pronounced. Per cent of ring-porous species is a measure that can be applied to fossil floras to yield information on paleoclimates; an analysis of a Sangamon flora fron the Toronto area is an example of the application of this measure.
Subject Area
Pollen|Paleobotany|Paleobotany|Paleoecology
Recommended Citation
Woodcock, Deborah, "Use of wood-anatomical variables of bur oak (Quercus macrocarpa) in the reconstruction of climate" (1987). ETD collection for University of Nebraska-Lincoln. AAI8810337.
https://digitalcommons.unl.edu/dissertations/AAI8810337