Tree-ring formation of eastern white-cedar (Thuja occidentalis L.) at a boreal lake in northwestern Quebec, Canada, was monitored using manual band dendrometers to (i) retrace cambial activity phases, (ii) evaluate the effects of flooding on radial growth, and (iii) analyze the relationships with meteorological factors. The daily circumferential activity of four trees at each of two sites, a riparian and an upland site, was recorded during the growing season of 1996, a year with an extreme spring flood. First cambium cell divisions occurred near June 9, followed by a distinct and sustained upward trend in the stem basal area until mid-July that reflected the earlywood formation. The strongly synchronous circumferential activity at both sites suggests no adverse flooding effect on growth of the riparian trees, which is explained by the rapid retreat of the water just before growth initiation in early June. The following month until mid-August was characterized by strong short-term fluctuations caused by alternating drought and rain periods and a slight downward trend of the basal area for six of the eight banded white-cedars. The dendrometers of two trees, the closest to the lake, showed a slight upward trend probably reflecting latewood formation. Pearson correlation with meteorological data indicated that precipitation was positively related to the daily changes in basal area of all trees except during the period of earlywood formation, which probably resulted from the high soil moisture after spring snow-melting. Mean and minimum air humidity were positively related and maximum temperature negatively related to the daily variations in stem circumference during the whole monitoring period, emphasizing the importance of the internal water status on stem size.

La formation des cernes annuels du cèdre blanc (Thuja occidentalis L.) en marge d'un lac boréal du Nord-ouest du Québec au Canada a été suivie au moyen de dendromètres circonférentiels manuels. L'étude avait pour but de (i) retracer les phases d'activité cambiale, (ii) d'évaluer les effets des inondations sur la croissance radiale et (iii) d'analyser l'influence de certains facteurs météorologiques. Les variations diurnes de la croissance ont été suivies chez quatre arbres dans deux sites, l'un en milieu riverain, l'autre supra-riverain durant la saison de croissance de 1996, une année de forte inondation. Les premières divisions cellulaires du cambium se sont produites le 9 juin et elles ont été suivies d'un accroissement soutenu de la surface terrière des tiges jusqu'à la mi-juillet, ce qui correspond à la formation du bois initial. Les dendromètres révèlent une croissance synchrone des arbres des deux sites, ce qui indique que l'inondation n'aurait que peu d'effets sur la croissance des arbres inondés. Cette absence de réponse pourrait être causé par l'abaissement du niveau du lac avant le déclenchement de la croissance en juin. À partir de la mi-juillet jusqu'au début d'août, la croissance connaît des variations reliées surtout à des épisodes d'assèchement des sols alternant avec des périodes de pluie. En août le taux de croissance a considérablement diminué; il s'agit de la période de formation du bois final. Les corrélations de Pearson avec des données météorologiques suggèrent que les précipitations sont le principal facteur influençant la croissance durant la formation du bois final, alors qu'en période de formation du bois initial, le sol demeure humide et les précipitations ont peu d'effet. La moyenne et le minimum journaliers de l'humidité de l'air sont positivement corrélés à la croissance, alors que la température maximale journalière a une relation inverse avec l'activité des dendromètres. Il apparaît clairement que l'eau est le facteur prédominant de la croissance des arbres dans le milieu étudié.

Mots clés: Dendromètr

The growth rings of eastern redcedar (Juniperus virginiana L.) often contain a high frequency of false intra-annual growth bands, which complicates the dendrochronology of this species. However, exactly dated false rings replicated among many trees can reflect major weather changes during the growing season. Sixty-one trees from two sites (Oklahoma and Kansas) were dated and used to compile replicated chronologies of false rings at both locations extending from AD 1700–2000. False-ring events during the modern instrumental era were compared with the daily weather data from nearby stations. Significant false-ring events occurred at both locations during years that experienced a dramatic late-growing season weather reversal, when an extended period of high temperatures and drought was followed by prolonged cool and wet conditions. Synoptic weather maps for these events indicate that all ten replicated false-ring events in the instrumental era occurred during the highly unseasonable penetration of a cold front into the region. However, none of the significant false-ring events occurred in the same year at both sites. These separate false-ring chronologies indicate that there may be phenological differences in the timing of radial growth in redcedar between Kansas and Oklahoma, and that the weather conditions responsible for false-ring formation often occur at the mesoscale and do not often impact central Kansas and northcentral Oklahoma simultaneously.

Although studies on stable-carbon isotopes in trees from temperate zones provide abundant paleoclimatic data, tropical trees are still understudied in this context. Therefore this study examined the variability of intra- and inter-annual stable-carbon isotopic pattern in several tree species from various tropical climates. The δ¹³C values of samples of 12 broadleaved trees (seven species) from various paleotropical and neotropical sites along a climatic moisture gradient were investigated. The inter-annual variability between species and sites was studied. Further the relationship between δ¹³C and precipitation time series was analyzed. Results show that tropical tree species show a similar variability in carbon isotopic composition as temperate tree species. Significant correlations between annual precipitation and tree-ring δ¹³C time series were negative. Successful crossdating of a tree-ring δ¹³C time series highlights the potential of carbon isotope measurements for tropical tree-ring analytical studies. Tropical broadleaved trees are able to capture a carbon isotopic signal in their annual rings even under everwet conditions and show good potential for paleoclimatic research.

The performance of the Hugershoff curve on fitting the growth trends of tree-ring series was tested using ring-width series with different starting years. The fitted values tend to be biased by tree-ring series close to pith, a phenomenon that was referred to as the “start-fitting problem”. We determined three parameters with specific biological age-related meanings for the Hugershoff growth curve, i.e. the maximum growth, the maximum slope and the maximum changing ratio of slopes. A set of modified Hugershoff curves with different starting years was proposed to mitigate the start-fitting problem. Behavior of the modified Hugershoff curves on tree-ring series standardizations was tested and discussed. The “end-fitting problem” suggests that deviations in one interval could bias the fitted values of other time periods by using the Hugershoff curve.

In recent decades, agencies charged with managing historic structures and sites have found dendroarchaeological studies increasingly valuable, given the ability of such studies to verify (or refute) accepted dates of construction. The Ximénez-Fatio House has well-documented historical and cultural significance for the state of Florida, as it is one of St. Augustine's oldest, best-preserved, and most studied historic properties. According to documentary sources, the two-story coquina-stone main house was reportedly built around 1797–1798, and included a one-story wing of warehouses, giving the house a distinctive “L” shape. Documentary evidence also suggests that a second story was added above the wing sometime between 1830 and 1842. However, after studying the building fabric itself, historical architects now believe the entire wing of the house was remodeled two decades later in the 1850s. Our goals were to: (1) determine the probable construction years for the original house and wing using tree-ring dating techniques, and (2) verify the probable construction year for the remodeling that occurred in the wing section of the house. A total of 74 core samples were extracted from longleaf pine (Pinus palustris P. Miller) timbers used to construct the house. Twenty-six were confidently crossdated both visually and statistically against each other to produce a 185-year floating tree-ring chronology. A statistically significant (p < 0.0001) correlation between our chronology and a longleaf pine chronology from Lake Louise, Georgia, anchors our chronology between 1673 and 1857. No cutting dates were obtained from the main house, but the lack of any tree rings that post-date 1798 supports the 1797 construction date. Furthermore, cutting dates obtained from beams in the first-floor wing revealed that the extensive remodeling of the wing likely occurred in the period 1856 to 1858 soon after the house had been purchased by Louisa Fatio in 1855.

A simple, quick, and inexpensive technique to improve visualization of aspen (Populus tremuloides) tree rings under the microscope, the ‘shadow technique’, is described. The technique assumes appropriate preparation of increment cores or cross-sections and works well on the lighter portions of the sample with fungus- and bacteria-free wood. The shadow technique was used successfully to elucidate tree-ring boundaries in small diameter (<5 cm DBH) aspen from northern Utah that commonly had >100 annual rings. Crossdating verified whether the elusive rings were missing or false rings. Aspen tree-ring measurement will be greatly enhanced with the shadow technique and preliminary investigation suggests it could be used on other species such as curlleaf mountain mahogany (Cercocarpus ledifolius).

It is important to acknowledge the essential and tireless work of all Associate Editors over the last eight years (names appear on the back cover of this issue), who have solicited reviewers and guided the review process on manuscripts received at Tree-Ring Research. Although Assoc. Editor Henri Grissino-Mayer has stepped down at the end of 2009, I am very pleased to welcome two new Assoc. Editors, Håkan Grudd (Sweden) and Alex Kirdyanov (Russia). Of course, the linchpin of our editorial process rests with expert reviewers, to whom I express the gratitude of the whole dendrochronology community. Below are reviewers for the period 2002–2009, some of whom have done more than one (5 or more in two cases!). Great apologies if we might have inadvertently omitted any of our valued reviewers.