• Changes In Wood Anatomy In Tree Rings Of Pinus Pinaster Ait. Following Wounding By Flash Floods

      Ballesteros, J. A.; Stoffel, M.; Bodoque, J. M.; Bollschweiler, M.; Hitz, O.; Díez-Herrero, A.; Department of Research and Geoscientific Prospective, Geological Survey of Spain (IGME); Laboratory of Dendrogeomorphology, Institute of Geological Sciences, University of Berne; Climatic Change and Climate Impacts, Institute for Environmental Sciences, University of Geneva; Department of Geosciences, Geography, chemin du Musée 4, University of Fribourg; et al. (Tree-Ring Society, 2010-07)
      This paper analyzes the anatomical response of Pinus pinaster Ait. following wounding by flash floods. A total of 14 wood samples were taken from 14 different scarred trees located on the river banks of the Arroyo Cabrera torrent (Spanish Central System). In addition, 20 increment cores were collected from undisturbed and healthy P. pinaster trees to build a local reference chronology. For the injured trees, analysis focused on growth changes in early earlywood (EE) tracheids, namely on differences in (i) lumen size; (ii) cell-wall percentage and cell-wall thickness; (iii) radial length and tangential width of tracheids; as well as (iv) in the abundance of resin ducts in earlywood (EW) and latewood (LW) following wounding. Results indicate that tissues bordering flash-flood wounds are characterized by reduced growth rates and a decrease of EE tracheid lumen area by 51%. In addition, cell-wall percentage increases by 34% in the increment rings formed after the event and significant changes are observed in the radial length and tangential width of EE tracheids. Observations on resin ducts do not yield any significant results. Based on these anatomical parameters, detecting and dating past flash-flood events in growth rings is now possible for Mediterranean species, specifically P. pinaster.
    • Dendrochronological Analysis Of Subfossil Fraxinus From The Middle And Late Holocene Period In Lithuania

      Vitas, Adomas; Group of Dendroclimatology and Radiometrics, Centre of Environmental Research, Faculty of Nature Sciences, Vytautas Magnus University (Tree-Ring Society, 2010-07)
      Dendrochronological investigations on subfossil European ash (Fraxinus excelsior L.) wood found in two bogs of Western Lithuania are presented. Radiocarbon dating has revealed that Fraxinus grew in the Middle and Late Holocene, from approximately 4700 BC to 1500 BC. It is proposed that the growth of Fraxinus at these bogs was limited by differing hydrological regimes. Rising soil water levels induced a long decline in radial growth followed by a sharp reduction (up to 51%) in ring widths before the trees died. Until now, forest history in Lithuania was mostly based on results from palynological studies. This research demonstrates the potential of using dendrochronology to extend the distribution record of Fraxinus in the Baltic region during different periods of the Holocene.
    • 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.