This study investigated the composition, age- and size-structure, and tree-ring relationships for an old-growth, warm-temperate, mixed-evergreen forest at the University of Tokyo Chiba Forest, Japan. A total of 32 tree species were recorded, which was dominated by Abies firma and Quercus acuta. Tsuga sieboldii dominated the recruitment after 1850, followed by Abies firma. After 1920, many individuals of Castanopsis, Cinnamomum, Cleyera and Quercus became established. The temporal pattern of conifer recruitment did not correspond to the record of strong wind events. Basal area increment in Abies firma and Castanopsis sieboldii trees increased throughout their lives, a trend not seen in the ring width index. Mean annual temperature was below the 100-year mean between 1920 and 1940 and 1960–1980, but increased rather abruptly after 1980. Mean annual precipitation decreased after 1960. Tree-ring releases are very common at the study forest, which are indicative of frequent small to moderate-sized disturbances. At least one release was recorded in every decade from 1890 to the present day, which is likely the primary causal factor promoting tree growth and recruitment. Our results suggest that early logging activities coupled with natural disturbances had a great influence on the developmental process and current structure of the study stand and that tree growth is varying in a manner consistent with forest dynamics.

The disastrous Tunguska explosion (TE) in 1908 uprooted trees in a radial pattern. Several trees in this area survived and kept growing in the post-Tunguska environment. We collected samples from surviving trees (14 and 131 years old at the time of the TE) that lived until collection in 2008 and another sample from a control tree farther from the blast epicenter (germination in 1928), which were analyzed by x-ray fluorescence (XRF) and prompt gamma neutron activation analysis. Chemical composition of xylem tracheids of the surviving trees revealed several patterns potentially related to the TE. A calcium peak is associated with the 1908 ring in both of the exposed trees, but additional high concentrations in adjacent rings could represent enhanced translocation of Ca over the whole sapwood as a response to defoliation from the TE. Sr and Mn anomalies near 1908 appeared in one exposed tree but not in the other. High-resolution XRF indicates Ca as well as Zn anomalies are primarily located in the earlywood of the rings, whereas peaks in Mn, Zn and Cu are more associated with the latewood. A directional response was evidenced by a wider zone of elevated Ca in the rings on the southern side toward the airblast, which might have experienced the greatest defoliation and perhaps enhanced root damage as the tree was rocked by the pressure wave. The TE event in the middle of the 1908 growing season must have triggered tree responses to deliver more nutritive resources to the crown in order to hasten restoring new leaves in the crown and to aid in structural repair.

Pinus edulis is one of the most ubiquitous tree species in the US Southwest. It accounts for over a fifth of the total number of trees in New Mexico alone. Its prevalence and relatively long-lived nature makes it an ideal candidate for dendroclimatological studies of the North American Monsoon. The problem occurs with delineating the boundary of the earlywood and latewood for sub-annual reconstructions. In this study, we present a novel method (“the resin duct method”) for delineating the latewood boundary using resin ducts of P. edulis from three sites in New Mexico. The climate sensitivity of partial ring widths of P. edulis is then explored and compared to co-occurring Pinus ponderosa, which has a clear latewood boundary. The method of using resin ducts for delineating latewood in P. edulis resulted in a statistically significant relationship when compared to the latewood widths of co-occurring P. ponderosa. Although we found a similar climate response of P. edulis when compared to P. ponderosa, P. edulis latewood was a poor predictor of North American Monsoon precipitation unlike P. ponderosa. However, P. edulis earlywood has a statistically significant correlation with cool-season precipitation, making it useful for cool-season climate reconstructions in the Southwest.

Since the late 19^th Century, geologists and naturalists working in the US Midwest have reported an abundance of tree macrofossils embedded in glacial and lacustrine deposits formed after the Last Glacial Maximum. The most widely-known of these sites is the Two Creeks type locality in Wisconsin. We report progress on development of a long tree-ring record from this subfossil wood in the US Great Lakes region, employing samples collected during a decade-long series of field campaigns at recently eroded lake shorelines, construction projects, and excavations, along with acquisition of archived samples collected from the 1950s to the 1980s during past lake erosion events. A previously-reported tree-ring chronology from the Two Creeks type locality reached ca. 250 years in length; here we used radiocarbon dates and tree-ring crossdating to develop a 1408-year tree-ring chronology (mainly spruce [Picea spp.] with some tamarack [Larix]) comprising a total of 135 overlapped tree-ring width series in three clusters from nine locations in eastern Wisconsin. The calendar age of the record is estimated with 46 ¹⁴C dates to between 14,500 to 13,100 cal BP. This is currently the oldest and only long tree-ring record in North America from the boreal environments of the Bølling-Allerød warm period during the transition from the Late Glacial to the Holocene.

We reconstruct pandora moth (Coloradia pandora Blake) outbreaks and climate from a 1572-year (435–2006 CE) ponderosa pine (Pinus ponderosa Dougl. ex Laws.) chronology from a lava flow in central Oregon. We took samples from 128 living trees and remnant logs and crossdated the samples using skeleton plots and COFECHA for quality control. After cutting out and removing those time periods from the chronology during which insects become the main limiting factor to growth, we examine the response of tree rings to climate. Evidence of species longevity (up to 877 years), presence of periodic pandora moth defoliations (13 total), and a significant relationship with the Palmer Drought Severity Index were observed (R² = 0.34, p < 0.001). Suppressions related to pandora moth outbreaks were recorded back to 618 CE, with a mean return interval of 104 years. Previous-fall to current-spring PDSI was reconstructed over 1376 years (630–2006 CE), where the most prolonged drought periods were 1136–1166 CE and the Dust Bowl 1924–1941. Our research documents longevity of ponderosa pine, resilience in the presence of multiple disturbances, and demonstrates a technique to separate insect outbreak signals from climate reconstructions in long chronologies while embracing the entire signal available in tree rings.

Dendroarchaeology in the Basque country is directed at improving our understanding of the cultural heritage preserved in, or originating from, northwestern Spain. To this end the emphasis is on the compilation of absolutely-dated tree-ring chronologies that can serve as a reference for accurately dating ancient structures such as buildings and shipwrecks. The current study focuses on 41 samples from radially-split oak planks that were mostly stored for reuse in a carpentry workshop in this region. The general consensus among historians is that these planks, and hence the buildings they are part of, date from the 15th and 16th Centuries. Our results show that the trees from which the planks were derived were cut down in the 15^th to 19^th Centuries, thus refuting this narrow time frame. The similarity of the planks’ growth patterns to the annual variations of Basque chronology ARAB4 (AD 1277–1819), which we reworked slightly and renamed ARAB8, confirms that this chronology is well-suited for establishing the age of timbers preserved in the cultural heritage in this region. The inclusion of the new series into ARAB8 significantly improves the replication of this master chronology from ca. AD 1300 onwards and extends it forward to AD 1849.

La dendrochronologie dans le pays Basque vise à améliorer notre compréhension du patrimoine culturel régional ou originaire du nord-ouest de l'Espagne. L'objectif est de rassembler des séries dendrochronologiques datées de manière absolue qui pourront servir de référentiels pour la datation de structures anciennes telles que les bâtiments et les épaves de bateaux. L'étude présentée ici porte sur 41 échantillons de chêne dérivés de planches fendues dans le sens radial, dont la plupart ont été stockés pour être réutilisées dans un atelier de charpenterie de cette région. Il est admis, d'après les historiens, que ces planches, et donc les bâtiments dont ils faisaient partie, datent des XVe et XVIe siècles. Or, nos résultats montrent que les arbres dont les planches ont été tirées ont été abattus du XVe au XIXe siècle, ce qui élargit considérablement la fourchette chronologique. La similitude entre les variations annuelles des cernes sur les planches et celles de la chronologie basque ARAB4 (AD 1277 à 1819), revue par nos soins et renommée ARAB8, confirme que cette chronologie est bien adaptée pour dater les bois du patrimoine culturel de cette région. L'inclusion des nouvelles séries au sein de la moyenne ARAB8 améliore de manière significative la puissance de la moyenne de cette référence de AD 1300 jusqu’à AD 1849.

La investigación dendrocronológica en el País Vasco está orientada a la profundización en el conocimiento del patrimonio cultural originario de la región y del noroeste de España. Una de las prioridades es la recopilación de series dendrocronológicas datadas de forma absoluta, que puedan servir de referencias para la datación de estructuras antiguas como edificios o restos de barcos. El presente estudio consiste en el análisis de 41 muestras procedentes de tablas radiales, extraídas del tronco por inserción de cuñas y rajado a la veta, la mayor parte de las mismas almacenadas por un carpintero de la región para su re-utilización. La hipótesis desarrollada por los historiadores sitúa la utilización de esta técnica (y por tanto los edificios que contienen este tipo de tablas) en los siglos XV y XVI. Sin embargo, los resultados del estudio muestran que los árboles de los que provienen estas tablas fueron talados en fechas comprendidas desde el siglo XV hasta el siglo XIX, alargando considerablemente el uso de esta técnica. La similitud entre los patrones de crecimiento de las tablas y las variaciones anuales de la cronología ARAB4 (1277–1819), que ha sido revisada y re-nombrada como ARAB8, confirma la idoneidad de esta cronología para la datación de elementos en madera del patrimonio cultural de la r

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.

Concern over the effects of removing fire-scarred partial cross-sections may limit sampling of live ponderosa pine to reconstruct fire history. We report mortality rates for ponderosa pine trees 20 to 21 years after removing fire-scarred partial cross-sections to reconstruct fire history. In 2015, following surveys every five years since 2000, we revisited 138 trees that were alive when we sectioned them in 1994/95 and 386 similarly sized, un-sectioned neighbor trees of the same species that were also alive in 1994/95. Between 1994/95 and 2015, a significantly greater proportion of sectioned than neighbor trees died, yielding average annual mortality rates of 3.3% versus 2.2%. However, many of the trees that died were likely killed by prescribed fires in 2002 and 2003 (64 sectioned plus neighbor trees). When we excluded these trees to assess the effect of fire-scar sampling rather than the effect of modern fires, the difference in proportion of dead trees was no longer significant and yielded average annual mortality rates of 2.1% versus 1.4% for sectioned and neighbor trees. We continue to suggest that sampling live, fire-scarred ponderosa pine trees remains a generally non-lethal method of obtaining information about historical fires that can supplement the information obtained from dead fire-scarred trees.