Search results for "dendrochronology"
showing 10 items of 71 documents
Revising midlatitude summer temperatures back to A.D. 600 based on a wood density network
2015
Annually resolved and millennium-long reconstructions of large-scale temperature variability are primarily composed of tree ring width (TRW) chronologies. Changes in ring width, however, have recently been shown to bias the ratio between low- and high-frequency signals. To overcome limitations in capturing the full spectrum of past temperature variability, we present a network of 15 maximum latewood density (MXD) chronologies distributed across the Northern Hemisphere extratropics. Independent subsets of continental-scale records consistently reveal high MXD before 1580 and after 1910, with below average values between these periods. Reconstructed extratropical summer temperatures reflect n…
δ2H, δ13C and δ18O from whole wood,α-cellulose and lignin methoxyl groups inPinus sylvestris: a multi-parameter approach
2015
Novel tree ring parameters – δ13C and δ2H from methoxyl groups – have been developed to reconstruct palaeoclimate. Tests with δ13C and δ18O derived from whole wood and cellulose samples, however, indicated differences in the isotopic composition and climate signal, depending on the extracted wood component. We assess this signal dependency by analysing (i) δ13C and δ18O from whole wood and cellulose and (ii) δ13C and δ2H from methoxyl groups, using Pinus sylvestris L. growing near Altenkirchen (Germany). Results indicate significant correlations among the time series derived from whole wood, cellulose, and lignin methoxyl groups. Compared with the whole wood samples, δ13C from methoxyl grou…
Changes in climatic signals of English oak tree-ring width and cross-section area of earlywood vessels in Latvia during the period 1900–2009
2012
Abstract We investigated changes in response of wood formation in English oak (Quercus robur L.) to climatic factors since 1900. It was hypothesised that the effect of winter and spring temperatures has weakened, while summer precipitation has become limiting. Increment cores were taken from 40 sites across Latvia. Tree-ring width and cross-section area of earlywood vessels were measured and cross-dated. Regional chronologies were built by pooling time series of trees within two regions of Latvia (western and eastern region), which differed in continentality. Climatic signals differed between the proxies (tree-ring width and earlywood vessel cross-section area) and between regions. Mean cro…
INFLUENZA DEL CLIMA SULLA CRESCITA DEL SUGHERO IN SOPRASSUOLI PRODUTTIVI SICILIANI.
2009
Abstract: Cork oak (Quercus suber L.) is usually dominant in silvopastoral systems in many areas of Sicily, where the trees are debarked periodically for cork production. In spite of the importance of cork and cork oak stands in Sicilian forests and the potential economic scenarios, few research works have been carried out on these systems. Given the importance of cork thickness in cork quality evaluation, the main objective of this work is to study cork growth in cork oak productive stands spread on the north (Nebrodi Mountains) and south-east (Iblei Mountains) of Sicily. Image analysis techniques were used on cork surfaces of transverse sections of planks to measure cork rings. Dendrochro…
On the hidden significance of differing micro-sites on tree-ring based climate reconstructions
2015
Tree-ring chronologies are commonly extended back in time by combining samples from living trees with relict material preserved in man-made structures or natural archives (e.g. lakes). Although spatially close, these natural archives and living-tree-sites often comprise different micro-climates. Inhomogeneous growth conditions among these habitats, which may yield offsets in growth-rates, require caution in data processing. Here we assess species-specific growth dynamics in two micro-habitats and their potential effects on long chronologies by combining tree-ring data from different living-tree-sites with an âartificialâ subfossil dataset. Well replicated (nâ>â80) Norway spruce (…
Filling the Eastern European gap in millennium-long temperature reconstructions
2013
Tree ring–based temperature reconstructions form the scientific backbone of the current global change debate. Although some European records extend into medieval times, high-resolution, long-term, regional-scale paleoclimatic evidence is missing for the eastern part of the continent. Here we compile 545 samples of living trees and historical timbers from the greater Tatra region to reconstruct interannual to centennial-long variations in Eastern European May–June temperature back to 1040 AD. Recent anthropogenic warming exceeds the range of past natural climate variability. Increased plague outbreaks and political conflicts, as well as decreased settlement activities, coincided with tempera…
The triumphal cross of the cathedral of Nevers: painting technique and examination
2019
The large polychrome wooden cross preserved in the Saint-Cyr et Sainte-Julitte cathedral in Nevers was badly damaged during the bombing in July 1944. Restored and put on display on a modern cross in front of the choir, the sculpture suffered a new fall in 2015. The conservation of the work, directed by DRAC-CRMH of Burgundy-Franche-Comté, was preceded by a phase of technical study. Micro-stratigraphic, taxonomic and radiometric analyses and the dendrochronology of the cross were carried out. The dendrochronology of the cross of Nevers and the comparison with radiocarbon dating place the elaboration of the work in the last quarter of the 12th century while confirming the contemporaneousness …
Climate/growth relationships of Brachystegia spiciformis from the miombo woodland in south central Africa
2010
Abstract We present five Brachystegia spiciformis Benth. (BrSp) tree-ring chronologies from the seasonally dry miombo woodland in south central Africa. Between 9 and 34 stem discs were collected from three dry and two wet miombo sites. All samples showed distinct growth rings, which were marked by terminal parenchyma bands. Site chronologies varied in length between 43 and 149 years. An increase in the number of growth ring anomalies in older trees, however, resulted in an increase in dating error and a decrease in between-tree correlations with increase in the chronology length. Annual precipitation variability accounted for some 28% of the common variance in the BrSp chronologies and we f…
Dendro-archaeological contribution to the history of forest exploitation: a case of the Gallo-Roman settlement of Oedenburg (Alsace, France) between …
2011
International audience
Influence of wood harvest on tree-ring time-series of Picea abies in a temperate forest
2012
Tree-ring width data are the prime source of high-resolution climate reconstructions covering recent mil- lennia. Their variations, from year-to-year, are calibrated against regional instrumental data to evaluate the strength of associations with temperature and precipitation records, though the level of variance explained by climatic variables is frequently less than 50%. Among the remaining factors affecting tree growth, the influence of forest management for tree-ring width time-series used to resolve annual climate reconstructions remains relatively unexplored. We here evaluate the impact of conventional single-tree harvesting on tree-ring data using a compilation of circumstantially ma…