Tree-Ring Bulletin, Volume 41 (1981)
ABOUT THE COLLECTION
Tree-Ring Research is the peer-reviewed journal of the Tree-Ring Society. The journal was first published in 1934 under the title Tree-Ring Bulletin. In 2001, the title changed to Tree-Ring Research.
The Tree-Ring Society and the Laboratory of Tree-Ring Research at the University of Arizona partnered with the University Libraries to digitize back issues for improved searching capabilities and long-term preservation. New issues are added on an annual basis, with a rolling wall of five years.
Contact the Editor of Tree-Ring Research at email@example.com.
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Test of a New Method for Removing the Growth Trend from Dendrochronological DataTests of the compound increment function, introduced by Warren (1980) as a means for removing the growth trend from dendrochronological data, are herein reported. In particular, the inter- and intra-site correlations of the residuals generated by the new method are compared with those generated by standard exponential fits. It is also shown that, in the presence of non-climatically induced responses, such as might arise from thinning, exponential fits can lead to spuriously high intra-site correlations. Accordingly, and because the new method's virtual elimination of negative and very low positive correlations, it appears to be the more satisfactory for portraying the growth trend.
The Smoothing Spline: A New Approach to Standardizing Forest Interior Tree-Ring Width Series for Dendroclimatic StudiesA new approach to removing the non-climatic variance of forest interior tree-ring width series, using the smoothing spline, is described. This method is superior to orthogonal polynomials because it makes no assumptions about the shape of the curve to be used for standardization. Also, because the spline curve can range continuously from a linear least squares fit to cubic interpolation through the data, it is far more flexible than polynomials and provides a more "natural" fit. For computing the spline, we found that specifying the Lagrange multiplier p which appears in the calculus of variation solution rather than the residual variance as suggested by Reinsche was both practical and more efficient. In effect, the smoothing spline is a one-parameter family of low-pass filters defined by p. We describe the general characteristics of these filters in the time and frequency domains and compute the response functions for several of them. The smoothing spline is an excellent tree-ring standardization method because its filtering characteristics are well defined. Its utility for dendroclimatology should be considerable since, outside of semiarid environments, sites similar to forest interiors predominate.
Dendroclimatic Calibration and Verification Using Regionally Averaged and Single Station Precipitation DataThe average ring-width index of two published chronologies from the eastern Tennessee climatic division was used as a single predictor variable in linear regression to reconstruct May June precipitation. Regression equations obtained using regionally averaged precipitation data from stations within the climatic division were compared with regressions obtained using single-station (Knoxville, Tennessee) data for comparable periods. The (regionally averaged) division data always provided the better calibration statistics for the regression equations. When the regressions calibrated using division data were verified with independent data for the climatic division and for Knoxville, the better results were always obtained for the division data. When regressions calibrated using single-station data were verified, the independent division data once again provided better results than the independent Knoxville data. Regionally averaged precipitation data also provided more satisfactory results than single- station data in a similar experiment for central Iowa, and probably provides better results in general for this type of dendroclimatic experiment.
Statistical Significance and Reproducibility of Tree-Ring Response FunctionsThis paper is concerned with the overall significance and reproducibility of the response function. A test of significance is devised which is based on the Binomial distribution. Combined with other tests, the method is then used to compare two different response functions to examine the reproducibility of climate-chronology response. Two approaches are used: the first compares two response functions covering the same period from the same site, based on independent chronologies of the same species; the second compares the response of a single chronology over two equal non-overlapping time periods. The results suggest that the response in the examples used is statistically reproducible on a site, and statistically stable over periods of time.
Principal Components Analysis of Tree-Ring SitesA principal components model for analyzing tree-ring data is presented which allows one to examine site heterogeneity and to compose chronologies of a new kind in a conceptually unified and computationally efficient manner. Using this model, one can develop chronologies that correlate better with local climate data than the standard chronology for a site and which can be tested for time stability within the framework of the model. The numerical procedures are described and applied to a specific tree site to illustrate their use and their usefulness. The tree-ring width data tested is from a white spruce (Picea glauca [Moench.] Voss) site in the forest-tundra ecotone of Yukon Territory. The results from the study of this and other sites indicate that more climatic information can be extracted using these techniques.