• Evaluation Of Goodness-Of-Fit Statistics From PRECON To Estimate The Strength Of Multivariate Tree Growth-Climate Associations

      Leblanc, David C.; Dept. of Biology, Ball State University (Tree-Ring Society, 2010-07)
      Although the primary purpose of response function analysis is to identify climate variables that have significant associations with tree radial growth, many researchers are also interested in assessing the strength of these associations. Existing response function programs use a liberal criterion to determine how many climate variables should be included in the analysis. The resulting response function models include a large number of predictor variables. The objective of this analysis is to determine if these response function models are over-fitted to the data used to calibrate them, resulting in over-estimation of strength of associations. PRECON was used to produce response functions for white oak chronologies from n = 149 sites, with separate response functions using 34 monthly climate variables or 10 seasonal climate variables. An analysis of goodness-of-fit statistics for response function calibration provided strong evidence of over-estimation of strength of associations. The degree of over-estimation was greater when 34 monthly climate variables were included in the models compared to models with10 season variables. There was much less evidence of over-fitting for the R-verif statistic that reflects strength of association between predicted and actual tree-ring indices that were not included in model calibration. The PRECON R-verif statistic is the best measure of the strength of multivariate growth-climate associations currently available.
    • Gender-Related Climate Response Of Radial Growth In Dioecious Fraxinus Mandshurica Trees

      Gao, Lushuang; Zhang, Chunyu; Zhao, Xiuhai; Gadow, Klaus; Key Laboratory for Silviculture and Conservation, The Ministry of Education, Beijing Forestry University (Tree-Ring Society, 2010-07)
      This paper presents an analysis of tree-ring growth patterns of male and female Fraxinus mandshurica trees from 1931 to 2007. The specific object was to study the response of radial growth to climate variables separately for male and female trees. The results show that the growth patterns in the two genders were similar during the mid-1950s to 1970s but different in the periods 1931–1940s and 1980–2007. In the period 1980–2007, the mean sensitivity and mean widths of the tree rings were significantly different between the genders (p < 0.05). The climate-growth response in female and male trees was also different. Female trees are sensitive to precipitation in November of the previous year, whereas male trees respond to mean temperature in November of the previous year. The results confirm that climatic sensitivity in male and female trees of dioecious species is different, yet this difference is not stable through time.
    • In Memoriam- Laurent Misson (1971–2010)

      Guiot, Joel (Tree-Ring Society, 2010-07)
    • In Memoriam- Marvin A. Stokes (1927–2010)

      Swetnam, Tom (Tree-Ring Society, 2010-07)
    • Lack Of Gender Bias In Citation Rates Of Publications By Dendrochronologists: What is Unique About This Discipline?

      Copenheaver, Carolyn A.; Goldbeck, Kyrille; Cherubini, Paolo; Department of Forest Resources and Environmental Conservation, Virginia Tech; University Libraries, Virginia Tech; Swiss Federal Institute for Forestry, Snow, and Landscape Research (WSL) (Tree-Ring Society, 2010-07)
      Most academic disciplines have a gender bias that exists in the recognition of research publications: women’s publications are cited at lower rates than men’s publications. In this paper, we examined whether a similar gender bias existed for publications by dendrochronologists. Tree-ring research is a fairly small field where males outnumber females, and therefore the sample size was limited to 20 female dendrochronologists and 20 male dendrochronologists. It was determined that native language (English or non-native English speaker), current employment (government or academic), and gender of the first-author do not significantly influence a paper’s probability of being cited. However, years since dissertation completion was a good predictor of a paper’s citation rate. We suggest that the high productivity of female dendrochronologists and a pattern of co-authoring with male colleagues bring the work of females to the attention of their male colleagues and thus eliminate the gender bias in citation of women’s work common to other disciplines.