Editors' Note

Center for Mediterranean Archaeology and the Environment (CMATE) Special Issue, Joint publication of Radiocarbon and Tree-Ring Research, also cited as Editors' Note. (2014). Radiocarbon, 56(4), V-V.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]

A new tree-ring width, delta-C-13 and C-14 investigation of the two creeks site

We have made isotopic and dendrochronologic measurements on material collected from the Two Creeks site. Radiocarbon dating of outside wood of four logs yielded an average age of 11,760 +/- 100 BP, in good agreement with results of Broecker and Farrand (1963) over 25 years ago. The range of 11,640 +/- 160 to 11,900 +/- 160 BP suggests a period of forest growth of 200-300 years, consistent with a ring-width chronology established by Kaiser (1987). Ring counting of five specimens gave a range of individual tree ages from 110 to 182 years, and width measurements indicate very low year-to-year variation in ring size. However, preliminary cross-dating of five samples produced a 202-year floating chronology. Stable-carbon isotope chronologies on cellulose from five-year ring groups show deltaC-13 scatter among trees typical of that found within modem sites, with some matches of isotopic maxima and minima. Some downward deltaC-13 trends may result from physiological response to rising lake levels (and/or cooling temperatures) at the site, which also produced very narrow rings in the outer ca. 50 +/- 20 years

A 1400-Year Bølling-Allerød Tree-Ring Record from the U.S. Great Lakes Region

Since the late 19th 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. © 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]

Variations of wood δ13C and water-use efficiency of Abies alba during the last century

International audienc

Tree-Ring Investigation of Holocene Flood-Deposited Wood from the Oneida Lake Watershed, New York State

Glacial deposition and fluvial/lacustrine sedimentation interact over terrains in central New York State to preserve a history of geological and hydrological events as well as hydroclimatic transitions. The lower reach of Fish Creek draining the eastern watershed of Oneida Lake, NY, is an area with prominent wood remains. This study explores a collection of 52 logs encased in organic-rich deposits exposed by bank erosion at three locations along Fish Creek near Sylvan Beach, NY, with respect to radiocarbon ages, species, and the crossdating potential of tree rings. Radiocarbon ages and successful tree-ring crossdating document what we interpret as seven major hydrologic episodes ca. 10 ka (i.e. ca. 10,000 cal yr BP), 7.4 ka, 6.8 ka, 6.4 ka, 5.5 ka, 3.1 ka and 2.2 ka cal BP, during which channel aggradation and tree burial may have been associated with abruptly increased flood frequency and/or high water tables. This pilot study establishes four floating tree-ring records: [1] early Holocene hemlock (Tsuga), mid-Holocene [2] walnut (Juglans sp.) and [3] sycamore (Platanus), and [4] late Holocene elm (Ulmus sp.), with sample sizes of 8-14 series of 55-135 years length. Despite the complexity of distribution of radiocarbon ages at each site, the wealth of well-preserved wood demonstrates great promise for understanding the paleoflood history of the Oneida watershed by documenting the magnitude, location, and timing of floods. Further additional systematic sampling can add and strengthen tree-ring dating and tree-ring based flood records, confirm results, and contribute to the Holocene hydrological history of the region. Copyright © 2015 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]

Utilisation des isotopes stables du carbone dans les cernes du bois comme bio-indicateurs des variations environnementales

National audienc

Tree Ring-Based Historic Hydroclimatic Variability of the Baja California Peninsula

The Baja California Peninsula is one of the most arid regions in Mexico, receiving an average of only 168 mm of precipitation annually. Climate change scenarios project drier and warmer conditions in the region at the end of this century driven by anthropogenic emissions of greenhouse gases. The growing demand for limited water supplies and the impacts of climate change pose a challenge to manage the already scarce water resources in the Peninsula. Analysis of historical hydroclimatic variability in the Peninsula is limited because most of the early instrumental climate data collection started only in the 1950s. In this study, we reconstruct past precipitation variability for the Peninsula using two tree ring chronologies from northern (Pinus monophylla) and southern (Pinus lagunae) Baja California. Our two reconstructions document multicentury hydroclimatic variability in the Peninsula, including events that turned out to be more extreme than those captured by modern instrumental records. Drought episodes are longer, more frequent, and more intense in the northern peninsula compared to the southern region. Multiyear dry and wet events in our two reconstructions exhibit broad spatial extent, affecting most of northwest Mexico and the western United States, which are mainly caused by broad-scale atmospheric circulation patterns such as El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). The results of this study allow framing current and projected droughts in a longer-term context, thus providing a better understanding of past climate variability and a basis for robust water resource management in the region. ©2020. American Geophysical Union. All Rights Reserved.6 month embargo; first published: 29 October 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]