Intra-annual patterns of tracheid size in the Mediterranean tree Juniperus thurifera as an indicator of seasonal water stress

Because climate can affect xylem cell anatomy, series of intra-annual cell anatomical features have the potential to retrospectively supply seasonal climatic information. In this study, we explored the ability to extract information about water stress conditions from tracheid features of the Mediterranean conifer Juniperus thurifera L. Tracheidograms of four climatic years from two drought-sensitive sites in Spain were compared to evaluate whether it is possible to link intra-annual cell size patterns to seasonal climatic conditions. Results indicated site-specific anatomical adjustment such as smaller and thicker tracheids at the dryer site but also showed a strong climatic imprint on the intra-annual pattern of tracheid size. Site differences in cell size reflected expected structural adjustments against cavitation failures. Differences between intra-annual patterns, however, indicated a response to seasonal changes in water availability whereby cells formed under drought conditions were smaller and thicker, and vice versa. This relationship was more manifest and stable at the dryer sit

Capture the time when plants reach their maximum body size by using the beta sigmoid growth equation

Of the many mathematical models proposed for capturing the dynamics of plant growth, the beta sigmoid function (BSF) is the newest and consequently is not well known to ecologists. A recent software package based on the Microsoft Excel macro, LEAF-E, was designed to promote the use of BSF, even though the performance of BSF and other growth models had not been compared. We developed R functions for fitting the BSF with a freer option for choosing the parametric number, and illustrated their performance using simulated data generated by four equations (the exponential, logistic, Gompertz, and von Bertalanffy equations), as well as dry weights of six crop species measured in growing seasons. Compared to other growth models, the BSF allowed for both symmetric and asymmetric growth curves, and thus the simulated data modeled the actual data quite well. It was demonstrated that the BSF was better than the above four traditional growth equations. In addition, the R functions developed here can facilitate future data fitting and model comparison for capturing plant growth dynamics. And the time when plants reach their maximum body size can be accurately obtained by using the BSF

Dendrochronological dating of wood from the Fountain of Youth Park Archaeological site (8SJ31), St. Augustine, Florida, U.S.A.

Settled in 1565 by the Pedro Mene´ndez de Aviles expedition, St. Augustine, Florida, holds great educational, historical, and anthropological interest for current researchers as the oldest continuously occupied European community in the continental United States. Archaeological excavations produced two large (ca. 20 cm diameter) posts from the Fountain of Youth Archaeological Park site. Our objective in this project was to use tree-ring dating to determine the outermost dates of the two posts and to use these dates to assist archaeological interpretations. Sample 8SJ31-2741 was pine and contained tree rings that were successfully crossdated using the Lake Louise reference chronology from southern Georgia to AD 1620–1668. Sample 8SJ31-2766 was a cypress sample that we could not crossdate using a nearby reference chronology from the Altamaha River in southern Georgia. The date for sample 8SJ31-2741 places its cutting and deposition within the Mission Period occupation and verifies that the Nombre de Dios mission village was still active and building after 1668 into the late 17th Century. Furthermore, the dendrochronological date confirmed the stratigraphic interpretation, suggesting that disturbance of the upper layers of the surface in this part of the site was perhaps not as disruptive to the soils as originally assumed. This project demonstrates the feasibility of dating wood extracted from sites from the historic Spanish-era period in the Southeastern US.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

Using Dendrochronology to Investigate the Historical and Educational Value of two Log Structures at Bear Paw State Natural Area, North Carolina, USA

During May 2013, the Bear Paw State Natural Area near Boone, North Carolina acquired an 11.5 ha tract of land and two log cabins from David Wray of Blowing Rock, North Carolina. Work was soon underway to determine the historical nature of these two buildings and to evaluate them for consideration for the National Register of Historic Places. A historic structure report, completed as a collaboration between Appalachian State University and the North Carolina Division of Parks and Recreation, was unable to discover much about the history of the two log cabins except that they were both likely moved to their current location in the early 20th Century. To determine when the cabins were built, we extracted core samples from logs in both cabins and compared the tree-ring patterns to region-wide, precisely-dated reference chronologies. We dated the tulip poplar tree-ring chronology from the Big Cabin to the period 1675-1859. Cutting dates on several of the logs revealed tree harvest likely occurred between fall 1859 and spring 1860. Some logs had outermost rings that dated to 1857 and 1858. Still, these logs may have been harvested a few years earlier, or some of the outer rings may have been lost during construction or sampling. We were unable to absolutely date an 81-year long American chestnut chronology from the Small Cabin. Our results confirmed that the Big Cabin was an Antebellum Period structure (pre-American Civil War) and therefore has potential historical significance. Because we still cannot tie this cabin to a historical figure or a historical event, the cabin cannot be nominated yet for inclusion in the National Register of Historic Places, but the identification of an original construction date for the cabin may contribute to further assessment for inclusion on a local or national register. In the meantime, we intend to use this cabin in annual summer workshops for undergraduate students taking courses at Appalachian State University so that more students can be exposed to the hands-on nature of scientific inquiry and can learn the value of dendrochronology for understanding human and environmental history. © 2017 by The Tree-Ring Society.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

Dendrochronological dating of the historic McKenzie Home, Meigs County, Tennessee, USA

The McKenzie Home is a one-story log structure located in Meigs County, Tennessee. The land tract where the cabin was originally built was purchased by the McKenzie family ca. A.D. 1820 to 1828, which makes the suspected construction date for the home sometime after 1820. Our objective was to date oak (Quercus spp.) cross-sections taken from original logs to accurately determine the year when the trees were cut and therefore when the structure was built. We created a master chronology from measurements taken along 12 radii from five oak sections using program COFECHA to first confirm internal crossdating among the measured radii and then using program ARSTAN to create a floating master chronology. Interactive detrending identified two likely disturbances that affected tree growth on all five oaks and these trends were subsequently removed using 32-year splines. The McKenzie floating chronology was then compared with a composite reference chronology created from four oak chronologies located in Tennessee, Kentucky, and Alabama. An interseries correlation coefficient of 0.412 (n  =  169 years, t  =  5.84, p < 0.0001) was obtained between the floating chronology and the anchored reference chronology, indicating a single year of tree harvesting in A.D. 1876. Cutting dates for the five samples indicate harvesting began in the early part of the growing season in 1876 and lasted until the end of the growing season or possibly into the dormant season of 1876–1877. The graphical and statistical crossdating evidence and cutting dates that confirm 1876 as the year of construction matches historical property and district records, which state the land was purchased by E.G. McKenzie, Sr. from his brother on 1 February 1876. The log structure has since been renamed the “E.G. McKenzie, Sr. Home.”This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]