Tree -ring characteristics are studied within and among stems of four Pinus ponderosa Laws. located at several semiarid sites in northern Arizona. Analyses are made of changes associated with certain physiological, height, and age gradients within the tree. Rings are grouped into twenty or forty-year intervals, are classified in four different arrangements, and the characteristics for the intervals are averaged and plotted to represent the gradients within the tree stem. Tree-rings are widest near the base and central portions of the stem. Ring width decreases with increasing age of the cambium, with increasing height within the young stem, with decreasing terminal growth, and with increasing environmental stress. Double (false or intra-annual) rings occur most frequently in the wide rings near the base and in the younger portions of the stem, or in the upper stem and branches of older trees. The frequency of rings which are locally absent (partial rings) is inversely related to ring width, and directly related to the potentiality for water stress conditions in the site or within the tree. Correlations among the year-to-year ring-width patterns throughout the tree generally increase with increasing tree age and frequency of water stress. They are high within the lower and central bole portions of older trees, but in the upper stem, in lateral branches, and in trees on the most extreme sites correlations among ring-width patterns are somewhat lower. Relative variability in widths of adjacent rings increases with decreasing ring width, increasing age, increasing height in the stem, and increasing environmental stress. First order serial correlation is frequently highest in older trees on semiarid sites. Many of these changes in ring characteristics within the tree are attributed to specific gradients or changes in auxin, food, and water supplies. A wide sampling of annual rings from the base of many semiarid site trees appears more appropriate for evaluating past fluctuations in climatic factors than an intensive sampling of rings at several heights in only a few trees.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/259791 |
| Date | 11 1900 |
| Publisher | Tree-Ring Society |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | Article |
| Rights | Copyright © Tree-Ring Society. All rights reserved. |
| Relation | http://www.treeringsociety.org |
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