ALBERT

Description: Available online 4 April 2013 Publication year: 2013 Source: Dendrochronologia The summer North Atlantic Oscillation (SNAO), derived from the first EOF of mean sea level pressure over the extratropical North Atlantic in July and August, has a close association with climate variability over the North Atlantic region, and beyond, on both short and long time scales. Recent findings suggested a teleconnection, through the SNAO, linking climate variability over Northern Europe with that of East Asia in the latter part of the twentieth century. Here we investigate the temporal stability of that teleconnection for the last four centuries using 4261 tree-ring width series from 106 sites and, additionally, ten climate reconstructions from East Asia. Our results showed a great potential in using tree-ring width (TRW) data to extend analyses of the SNAO influence on East Asian climate beyond the instrumental period, but preferably with a denser network. The strongest SNAO-TRW associations were found in central East Asia (in and around Mongolia) and on the eastern edge of the Tibetan Plateau. In addition, the analysis showed that the association between the SNAO and East Asian climate over the last 400 years has been variable, both among regions and at specific sites. Moreover, a clear difference in the SNAO-TRW associations was found on two examined time scales, being stronger on longer timescales. Our results indicate that TRW data can be a useful tool to explore the remote influence of the SNAO on East Asian climate in the past.

Description: Publication date: Available online 26 September 2013 Source: Dendrochronologia Author(s): Stella Bogino In 1931, Krebs and Fischer, published El pluviómetro secular (The centenary pluviometer) an analysis of tree rings of Prosopis caldenia Burkart (caldén) in the central Argentinean Pampas which, according to the date, may be considered as one of the first dendrochronological studies in South America.

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 22 June 2011 X., Arnan , B.C., López , J., Martínez-Vilalta , M., Estorach , R., Poyatos Trees can reach ages that in some cases amount to thousands of years. In the Mediterranean region, olive trees (Olea europaea) have traditionally been considered a particularly long-lived species. The main objective of this study was to assess the age of large olive trees considered to be millenarian and classified as monumental trees in northeastern Spain. We extracted cores of 14 individuals and obtained 8 sections of trees which had already been cut in the area where the largest olive trees in the northeastern Iberian Peninsula are found. The age of the sampled olive trees was assessed by counting the...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 12 June 2011 Filipe, Campelo , Ignacio, García-González , Cristina, Nabais In this paper, we present the package detrendeR, a Graphical User Interface to facilitate the visualization and analysis of dendrochronological data, using the R computing environment. This package offers an easy way to perform most of the traditional tasks in dendrochronology: detrending, chronology building and graphical presentation of time series. The advantage of detrendeR, compared with the program ARSTAN, is the graphical interface that provides the user with an easy way to use R language, rich in graphics and handling routines, with no need to type commands. The detrendeR uses a simple and familiar dialog-box interface and it can read...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 12 June 2011 Marek, Ježík , Miroslav, Blaženec , Katarína, Střelcová , Ľubica, Ditmarová The link between the dynamics of beech (Fagus sylvatica L.) diameter changes, recorded by mechanical dendrometers, and the weather activity was studied at a submontane site in central Slovakia between 2003 and 2008. A new approach was presented by constructing seasonal increment chronologies, dividing them into shorter periods and joining them across several seasons to analyse the main influencing factors. For this purpose, response functions and correlation functions and their intra-seasonal moving variants were calculated. The photoperiod appeared to be synchronising the culmination of the seasonal dynamics of diameter changes; however, the main factors influencing the seasonal dynamics were weather...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 20 May 2011 Anna, Cedro , Mariusz, Lamentowicz A comparison of the tree-ring width of pines growing in areas adjacent to a peat bog and on a Baltic raised bog dome suggests that cambium activity in each tree group is affected by different factors. The study was aimed at pinpointing effects of meteorological factors on two pine populations growing under different hydrological conditions. The study further sought to identify periods during which anthropogenic pressure affected the two populations. The pines growing on mineral soil were characterised by ring-width growth–climate responses typical of this part of Europe, whereas the tree-ring growth of the pines growing on the peat bog...

Description: Publication year: 2012 Source: Dendrochronologia Kathryn Allen, David M. Drew, Geoffrey M. Downes, Robert Evans, Patrick Baker, Michael Grose The great majority of dendroclimatological work in Australia has thus far relied on ring-width chronologies only. We report novel results from a pilot study that show the potential to develop density-based climatically sensitive chronologies from two long-lived conifers endemic to Tasmania: Pencil Pine and Celery Top Pine. Cross-dating of average ring density profiles within each of the two sites examined was comparable with the better replicated ring-width chronologies from the sites. Cross-dating potential for maximum density was also indicated. Correlations between density and climate for both species were stronger and more persistent across a window of several months than correlations between ring width and climate. These stronger correlations suggest that temperature reconstructions based on average density may be possible. The ability to develop high resolution temperature-sensitive chronologies would allow for spatial comparisons across regions such as Tasmania that are affected by multiple broad-scale climate systems. A particularly novel result was the finding that maximum density was significantly related to stream-flow at the end of the growing season. Further work is required to assess the potential to reconstruct temperature, and to reconstruct stream-flow for important Tasmanian catchments over the past 500–800 years.

Description: Publication year: 2012 Source: Dendrochronologia Hannu Hökkä, Hannu Salminen, Erkki Ahti The climate conditions of the current and previous growing seasons have been shown to influence growth of coniferous trees in mineral soils sites. These dependencies may be different in peatlands where growth is generally more dependent on variations in soil water conditions. In the Nordic and Baltic countries, millions of hectares of peatlands and wetlands have been drained in order to enhance forest production. These drainage networks do not guarantee stable soil water conditions for the whole stand rotation. It is thus likely that precipitation in particular may have a different influence on annual growth in peatland to that in mineral soil sites. We studied the effect of precipitation and temperature on the inter-annual diameter growth of Scots pine ( Pinus sylvestris L.) in Finland in drained peatland forests. The diameter growth data were limited to periods when growth response to drainage had levelled out. For comparison, growth data were also collected from adjacent mineral soil trees. The climate variables were monthly mean temperature and precipitation in a given location estimated from observations at the nearest weather stations by means of spatial smoothing. We used mixed linear models in describing the annual diameter growth of individual trees as a function of tree size and stand properties and expressed the residual variation as a function of climate parameters. The peatland and mineral soil growth variations showed different dependence on climate parameters. Peatland trees within 5 m of a ditch showed different climate responses compared to those located further away. Precipitation in July was negatively correlated with the diameter growth of peatland trees but there was no correlation with temperature. Growth of trees in mineral soils was positively correlated with March and April mean temperatures and May and June mean precipitation. The residual growth indices showed largely similar patterns in peatlands and mineral soil sites.

Description: Publication year: 2012 Source: Dendrochronologia Keyan Fang, Xiaohua Gou, Fahu Chen, Yingjun Li, Fen Zhang, Miklos Kazmer Individual tree-ring series may show changed growth trends and divergent climate–growth associations even within a site, highlighting the need to examine tree growth and its climate association before building a chronology. We provided a case study for the stratification and temporal variability of tree growth and its climate associations of individual cores for three mountain ranges in north central China. Tree growth is mainly limited by moisture conditions in previous July–September and current June–August. Repeated sampling and field investigations of Picea wilsonii at Xinglong Mountain over a growth year of 2004 suggested that the growing season is from about the end of April to the end of September. It appears that the moisture conditions in previous and current growing seasons are crucial for tree growth in this region. However, a decrease in drought limitation was observed for a few tree-ring series. We thereby built the pooled chronology and sub-site chronologies with only drought-sensitive tree rings similar climate–growth relationships from the three mountain slopes. Growth disturbances of tree-ring series are detected by checking the occurrence of successively low values of the biweight series, which are treated by fitting a flexible curve.

Description: Publication year: 2012 Source: Dendrochronologia Esther Jansma, Rowin J. van Lanen, Kit Sturgeon, Steve Mohlke, Peter W. Brewer Dendrochronological data formats in general offer limited space for recording associated metadata. Such information is often recorded separately from the actual time series, and often only on paper. TRiDaBASE has been developed to improve metadata administration. It is a relational Microsoft Access database that allows users to register digital metadata according to TRiDaS, to generate TRiDaS XML for uploading to TRiDaS-based analytical systems and repositories, and to ingest TRiDaS XML created elsewhere for local querying and analyses.

Description: Publication year: 2012 Source: Dendrochronologia Igor Drobyshev, P. Charles Goebel, Yves Bergeron, R. Gregory Corace The study of forests dominated by red pine ( Pinus resinosa Ait.), one of the few fire-resistant tree species of eastern North America, provides an opportunity to reconstruct long-term fire histories and examine the temporal dynamics of climate forcing upon forest fire regimes. We used a 300-year long spatially explicit dendrochronological reconstruction of the fire regime for Seney National Wildlife Refuge (SNWR, 38,531 ha), eastern Upper Michigan to: (1) identify fire size thresholds with strong vs. weak climate controls, (2) evaluate effect of landform type (outwash channel vs. sand ridges) in modifying climate–fire associations, and (3) check for the presence of temporal changes in the climate control of large fire events over the time period 1700–1983. We used a summer drought sensitive red pine chronology (ITRDB code can037 ) as a proxy of past fire-related climate variability. Results indicated that fires 〉60 ha in sand-ridge-dominated portions of SNWR and 〉100 ha in outwash channels were likely climatically driven events. Climate–fire associations varied over time with significant climate–fire linkages observed for the periods 1700–1800 (pre-EuroAmerican), 1800–1900 (EuroAmerican settlement) and 1900–1983 (modern era). Although an increase in fire activity at the turn of 20th century is commonly associated with human sources of ignitions, our results suggest that such an increase was also likely a climatically driven episode.

Description: Publication year: 2012 Source: Dendrochronologia Maxim Yermokhin This article presents for the first time Scots pine tree-ring chronology created from historical timber (XVII–XIX cc.) from central Belarus. The chronology includes 59 tree-ring series which were collected from the different wood structures in the Nesvizh castle. This samples show different stages of the castle renovations. The chronology presented in this paper embraces 222 years covering the period between 1608 and 1829.

Description: Publication year: 2012 Source: Dendrochronologia Pavel Pavlovich Silkin, Natalia Victorovna Ekimova This study addressed distribution of calcium and strontium in Siberian spruce ( Picea obovata Ledeb.) and Siberian fir ( Abies sibirica Ledeb.) tree-rings and its dependence on these woody species cell structure. Calcium concentration was found to decrease gradually from earlywood to latewood, whereas strontium showed an opposite trend. However, their trends at the scale of several rings are co-directed in the samples analyzed. A strong linear relationship was identified between the distribution of Sr/Ca concentration ratio and tree-ring density profile for both woody species. Radiographic density of Siberian spruce tree-ring cell walls and Ca and Sr concentrations in them were determined to have negative correlation with cell wall thickness. In earlywood of annual rings of a spruce the radiographic density of cell wall reaches 2.0 g/cm 3 and decreases to 1.2 g/cm 3 in latewood. The hypothesis put forward in this study to explain these strontium and calcium distributions in the tree-rings is that the concentrations of the element ions change with development of different cell wall layers. The high value of radiographic density of a cellular wall in earlywood and its relationship with cell wall thickness can be explained by the presence of ions of calcium in a cellular wall. Ions of calcium absorb X-ray radiation more strongly in comparison with light chemical elements. It can become the reason of observable relationship between radiographic density of cell wall and cell wall thickness.

Description: Publication year: 2012 Source: Dendrochronologia Xiaohua Gou, Fen Zhang, Yang Deng, Gregory J. Ettl, Meixue Yang, Linlin Gao, Keyan Fang Tree-line ecotones are strongly climatically limited and serve as potential monitors of climate change. We employed annual growth increment from tree-rings, and tree density and age structure data derived from two Juniperus przewalskii tree-line sites in the eastern part of the Qilian Mountains, northeastern Tibetan Plateau, to detect the responses of tree growth and population dynamics to climate change. High temperature favors tree growth and is associated with increased tree density at tree-line, and an advance in tree-line position. Significantly positive correlations were found between ring-width and mean monthly air temperatures in current and previous June, July and August. Tree recruitment began to increase rapidly at the two sites after the Little Ice Age, but then decreased starting in the 1970s. The number of trees established coincides with temperature changes. The warming trend after the Little Ice Age favors increases of tree density and an advance of tree-line. The majority of trees established during the period of 1931–1970, which coincides well with the rapid radial growth of the trees.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 1 X. Arnan, B.C. López, J. Martínez-Vilalta, M. Estorach, R. Poyatos Trees can reach ages that in some cases amount to thousands of years. In the Mediterranean region, olive trees ( Olea europaea ) have traditionally been considered a particularly long-lived species. The main objective of this study was to assess the age of large olive trees considered to be millenarian and classified as monumental trees in northeastern Spain. We extracted cores of 14 individuals and obtained 8 sections of trees which had already been cut in the area where the largest olive trees in the northeastern Iberian Peninsula are found. The age of the sampled olive trees was assessed by counting the number of annual growth rings. Tree rings did not cross-date well, neither within nor between individuals, but boundaries between likely annual rings were clearly distinct. We found a linear relationship between DBH and tree age (in years) (Age = 2.11 × diameter(cm) + 88.93, R 2 = 0.80), which was used to estimate the age of unsampled olive trees. The maximum estimated age (627 ± 110 years) is among the greatest ages reported for olive trees around the world (700 years) and among the oldest trees in Mediterranean ecosystems.

Description: Publication year: 2012 Source: Dendrochronologia Marc Macias-Fauria, Aslak Grinsted, Samuli Helama, Jari Holopainen Proxy data forms natural time series used to lengthen instrumental climatic records, and may contain a significant portion of autocorrelation. Increased serial correlation limits the number of independent observations, not satisfying the assumptions of conventional statistical methods. We estimate the significance of calibration and verification statistics used in dendroclimatic reconstructions by combining Monte-Carlo iterations with frequency (Ebisuzaki) or time (Burg) domain time series modelling. Significance tests are presented for Coefficient of Determination ( R 2 ), Coefficient of Correlation ( r 2 ), Reduction of Error (RE) and Coefficient of Error (CE) for time series ranging from very low to very high autocorrelation. Increased autocorrelation implies higher occurrences of relatively high but spurious reconstruction statistics. Ebisuzaki time series modelling shows greater robustness and its use is recommended over Burg's method, which penalizes the restriction in the number of autocorrelation coefficients imposed by the Akaike Information Criterion. Positive RE and CE values, traditionally viewed as successful reconstruction statistics, are not necessarily significant and depend on the temporal structure of the time series used. This approach is further implemented successfully to compute confidence intervals based on the temporal structure of the residuals of the transfer function. A Matlab ® package and a Windows executable file for non-Matlab ® users are provided to perform the described analyses.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 1 Kristof Haneca, Vincent Debonne A detailed dendrochronological survey was performed on the medieval roofs of the Church of Our Lady (CoOL) in Damme, Belgium. Seen its complex architectural history, special attention was paid to the identification of consecutive building phases, based on combined architectural historical research and tree-ring dating. In total 64 increment cores were taken throughout the roof structures of the CoOL. All roof timbers are made of European oak ( Quercus robur / petraea ), of which only few have surviving sapwood or bark. Tree-ring dating confirms the late 13th/early 14th century construction date of the roofs. For all chronologies that were composed, the highest correlation values are found with reference chronologies covering the catchment area of the river Meuse. From the dating results of the timbers of the CoOL it becomes clear that the same timber source was used for nearly a century. On several of the examined roof timbers, rafting joints were observed, demonstrating that the timbers were indeed tied together as a raft and floated down the river. By implementing sapwood estimates in a Bayesian chronological model (OxCal), tree-ring series with surviving sapwood from coeval roof structures were combined in order to narrow down the time range for the felling date. Based on the refined interpretation of the felling dates, several consecutive building phases can now be identified and dated, leading to a new interpretation of the architectural history of the CoOL. Intriguingly, a marked interruption in building activities is observed around 1300. Probably this is related to the instable political situation at that time, caused by the armed conflict that emerged between the Count of Flanders and the king of France. Since Damme served as the outport of the riotous city of Bruges, it was alternately seized by the French and Flemish, both consuming considerable amounts of timber and other building materials for military fortifications. Potentially this led to a shortage in building materials and provoked a stop in building activities. This paper demonstrates the power of Bayesian models to refine the interpretation of dendrochronological dates in architectural analyses of medieval historical buildings.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 1 Kristina Sohar, Adomas Vitas, Alar Läänelaid Pedunculate oak ( Quercus robur L.) is one of the widely used and dendrochronologically investigated species in Europe. Still, it is a problematical dating object if its outermost section is missing partly or totally. Thus, we need sapwood estimation of living trees. As sapwood amount varies geographically, numbers of sapwood rings have been published for different regions in Europe but no such estimation has been done for the Baltic States yet. Therefore, this paper deals with the estimation of pedunculate oak sapwood growing in the eastern Baltic region, i.e. in Finland, Estonia, Latvia, and Lithuania. In total, 668 oak core samples of living trees from 43 stands were investigated. Ring widths were measured and the number of sapwood rings was determined according to two criteria: difference of colour and absence of tyloses in earlywood vessels. The samples were divided into two sets, according to the t H -values between site chronologies and the major geobotanical sub-provinces. Thus, the nine Finnish and western Estonian sites were attributed to the western region and the 34 eastern Estonian, Latvian and Lithuanian sites to the eastern region. As the result of a statistical analysis, we explain that the number of oak sapwood rings ranges from 4.09 to 20.85 and 6.45 to 18.02 within 95% confidence limits in the western and eastern regions, respectively. For the three Baltic countries and southern Finland in general, we recommend to consider a sapwood estimate of 6.18–18.71 rings. Regarding earlier studies, the general European trend of decreasing sapwood ring number towards the east was confirmed. A geographical pattern of eastward decrease of the median sapwood ring number was noticed in the Baltics as well. The chronology based upon 668 samples of living oak trees from all sites covered the period of 1631–2008.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 1 Julia Bartens, Henri D. Grissino-Mayer, Susan D. Day, P. Eric Wiseman Live oak ( Quercus virginiana Mill.) is a long lived, broadleaf, evergreen species native to the lower Coastal Plain of the southern and southeastern United States and is frequently planted in the urban environment. However, live oak has received limited attention for its potential for dendrochronological analyses possibly because its growth-ring boundaries may be less defined due to the absence of a distinct dormancy period. The objective of this explorative study was to determine whether live oak rings in both urban and historic trees could be accurately identified and measured for dendrochronological applications. One hundred urban live oaks were assessed as well as four cross-sectional specimens from historic sites in the southeastern United States. Age of all cored live oak ranged from 7 to 29 (average = 16.8 rings), while cross-sections were taken from trees with an average age of 175 years. A chronology was created from cores that had the highest interseries correlations ( n = 27), resulting in an average interseries correlation of 0.654. The analysis of live oak cross sections revealed that the rings on live oak are very faint and barely discernible, delimited mainly by a faint row of earlywood vessels with no or barely visible terminal parenchyma. Rings on these sections were erratic (i.e., fading out along the circumference) and non-concentric (i.e., a particular ring could be both wide and narrow at certain points along the circumference) so that any attempt to measure the rings on opposing radii would have produced meaningless results. However, based on the results of this study, we conclude that the dendrochronological analysis of live oak is possible with careful sample preparation and analysis and that results would be reliable, even for urban trees. Results of this study suggest that urban tree-ring series with higher interseries correlations were more vigorous than those with lower values, suggesting that urban environmental stresses related to individual sites may decrease the usefulness of crossdating techniques for evaluating annual rings on younger, urban trees.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 1 Rob Wilson, C. Richard Bates Following the successful utilisation of lake preserved sub-fossil woody material to extend living Scots pine chronologies in Scandinavia, ongoing research in the Scottish Highlands aims to build a similar multi-millennial long climatically sensitive pine chronology. This paper details explorative research testing the use of sonar methods to facilitate the search for sub-fossil material in lake environments. Although the method clearly identifies elongate anomalies that are consistent with submerged tree stems in water depths 〉1.5 m, it does not allow the identification of sub-fossil wood remnants in shallow water (〈1.0 m) or heavily vegetated bays. Therefore, for the successful survey of lakes, a combination of traditional and sonar methods must be applied. Ongoing research will now explore the utilisation of these methods to more remote locations where boat access is not possible.

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 4 Yongxiang Zhang, Xuemei Shao, Martin Wilmking Knowledge of the spatial pattern and temporal relationships between tree-growth and climatic factors are important not only for the projection of forest growth under varying climate but for dendroclimatology in general. Here, we systematically investigated tree-growth climate relationships of Picea crassifolia at upper treeline in the Qilian Mts., northwestern China. 297 trees from eleven sites, covering a large part of the natural range of this species, show increasing and partly divergent correlations with temperature in the most recent decades. The dominant signal at all sites was a strengthening of negative correlations of annual radial growth with summer temperature. In a subset of trees at six sites, a strengthening positive correlation with summer temperatures existed as well. Wetter and high altitude sites tended to show a higher percentage of trees that are positively correlated with warming temperatures, indicating that some individuals there may take advantage of warmer conditions. Divergent responses between the two sub-populations clustered by their response to climate factor were significantly stronger in the last 30 years compared to earlier time slices. In the same time frame, hydrothermal conditions of the investigation area changed to a drier and warmer combination. Drought conditions, most likely affecting the radial growth of most P. crassifolia , have been intensifying over time and expanding spatially from the middle Qilian Mts. to most of our study area during the last half century. While explanations such as methodological effects due to trend removal or human disturbance at the sampling sites might be able to explain the result at single sites, the spatial and temporal co-occurrence of large scale changes in climate and tree growth suggests a causal link between them.

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 3 Martin de Luis, Klemen Novak, José Raventós, Jožica Gričar, Peter Prislan, Katarina Čufar Research was carried out on the wood formation process and the intra-annual density fluctuations (IADFs) in Mediterranean Aleppo pine ( Pinus halepensis Mill.) trees from the coastal site of Guardamar, and inland Maigmo in south-eastern Spain. Samples taken at breast height of the trees were inspected to define the frequency of tree rings with latewood-like cells in earlywood (E-ring) and with earlywood-like cells in latewood (L-ring). L-rings were generally more frequent, especially on the warmer, dryer, coastal site of Guardamar. Dendrochronological techniques using tree-ring features vs. climate showed that L-rings were formed in Guardamar when August and/or September precipitation was higher than normal and in Maigmo when August precipitation was higher than normal. The formation of E-rings was promoted when winter and early spring were warmer than long term average. By studying intra-annual tree-ring formation at a cellular level, we found that at Maigmo in 2004 (MAI2004) all monitored trees presented a normal ring with normal earlywood and latewood and gradual transition between both. At Guardamar in 2005 (GUA2005) a typical L-ring was formed in the majority of monitored trees. In GUA2005 the wood formation started before February and the transition from early- to latewood occurred in late spring. In summer, the cambial cell production occurred at a very low rate, but an increased production of xylem cells took place in September when the amount of precipitation was twice as high as the long term average. During this period, a band of earlywood-like cells was formed, followed by the production of latewood-like cells that continued until the end of December. The normal ring in MAI2004 was formed because climatic factors triggering IADF did not occur (no precipitation in August 2004). After a modest cell production of cambium in September, only few latewood-like cells were produced. According to the strong agreement of results obtained from studying long-term dendrochronological series and intra-annual information on wood formation, such combined study indicates a high potential for use in explaining the environmental signals registered by a tree during different phases of wood formation.

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 1 Peter H. Nishimura, Colin P. Laroque Despite their suitability for dendroclimatological research, the boreal regions of central and western Labrador remain under-researched. In an attempt to evaluate the growth trends and climatic response of this region's trees, master chronologies have been developed for its four dominant conifer species. Balsam fir ( Abies balsamea (L.) Mill.), white spruce ( Picea glauca (Moench) Voss), black spruce ( Picea mariana (Mill.) Britton, Sterns, Poggenb.) and eastern larch ( Larix laricina (DuRoi) K. Koch) were sampled systematically within a 3 × 4 grid of twelve sites at the intersection of 62°W, 64°W and 66°W longitude, and latitudes 52°N, 53°N, 54°N and 55°N. The two most dominant species at each site were sampled, yielding a total of twenty-four master chronologies, all of which reflected a highly significant common signal at each site. The chronologies were subjected to a response function analysis to determine the nature of the growth–climate relationships in the region. Summer temperature proved to be the predominant limiting factor with regard to radial growth at most sites. The onset of the optimum temperature regime, however, varies across the network of sites, revealing evidence of a gradient of continentality in the data. Growth–temperature correlations indicated a significant relationship with July temperature at most eastern sites, while western sites tended to correlate with May, June and August temperatures. Central sites tended to correlate with June–July temperatures. We interpret these results as demonstrating the bioclimatic gradient of change between coastally proximal, maritime-influenced sites and inland, continentally influenced locales. This transition occurs approximately 330 km inland from the open Labrador Sea.

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 4 S. Szymczak, M.M. Joachimski, A. Bräuning, T. Hetzer, J. Kuhlemann Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope–climate relationships. This study focuses on wood of Corsican Pine trees ( Pinus nigra ssp. laricio ) as this tree species allows to reconstruct the long-term climate evolution in the western Mediterranean. In a pilot study, we concentrated on methodological issues of sample preparation techniques in order to evaluate isotope records measured on pooled whole tree-ring cellulose and whole tree-ring bulk wood samples. We analysed 80-year long carbon and oxygen chronologies of Corsican Pine trees growing near the upper tree line on Corsica. Carbon and oxygen isotope records of whole tree-ring bulk wood and whole tree-ring cellulose from a pooled sample of 5 trees were correlated with the climate parameters monthly precipitation, temperature and the self-calibrating Palmer Drought Severity Index (sc-PDSI). Results show that the offsets in carbon and oxygen isotopes of bulk wood and cellulose are not constant over time. Both isotopes correlate with climate parameters from late winter and summer. The carbon and oxygen isotope ratios of cellulose are more sensitive to climatic variables than those of bulk wood. The results of this study imply that extraction of cellulose is a pre-requisite for the reconstruction of high-resolution climate records from stable isotope series of P. nigra ssp. laricio .

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 3 Annie Deslauriers, Sergio Rossi, Audrey Turcotte, Hubert Morin, Cornélia Krause Continuous measurements of stem radius variation in trees are obtained with automatic dendrometers that provide time series composed of seasonal tree growth and circadian rhythms of water storage and depletion. Several variables can be extracted from the raw data, such as amplitude and duration of radius increase and contraction, which are useful for understanding intra-annual tree growth, tree physiology and for performing growth–climate relationships. These measurements constitute a large dataset whose manipulation needs numerous algorithms and automatic procedures to efficiently and rapidly extract the information. This paper presents a three-step procedure using two SAS routines to extract the time series describing radius variation and associate them with environmental parameters. The first routine organizes and corrects data and generates outputs in the form of files and plots to visualize the results and improve data correction (first step). The second step consists of a reclassification of the hours of contraction or expansion that have been misclassified by the automatic process. The second routine classifies the daily patterns of stem variation into the three phases of contraction, expansion and radius increment and associates the environmental parameters (third step). An example of the procedure is given, with an explanation of the outputs generated. The advantages and shortcomings of the procedure and its importance for the intra-annual analyses of tree growth are discussed.

Description: Available online 3 October 2012 Publication year: 2012 Source: Dendrochronologia In order to detect the response of trees to environmental pollution in Shenyang during the last century, tree rings of two 100+ year old Chinese pine ( Pinus tabulaeformis Carr.) were analyzed for nine trace element concentrations (K, Ca, Mg, Mn, Cu, Zn, Al, Pb and Cd) and compared to local environmental change. The concentrations of Cu, Zn and Al had significant ( p 〈 0.01) increasing trends after 1940s and correlated significantly ( p 〈 0.01), with increasing production of nonferrous metal from local industrial processing. Concentrations of nutrient element (K, Ca and Mg) showed significant ( p 〈 0.01) increasing trend from heartwood to sapwood with declines in the last three decades. Significant correlation between climatic factors and element concentration in tree rings were also found, in which the temperature (November to May) and relative humidity in April and May showed significant positive correlation with Ca, Zn and Cu ( p 〈 0.05) as well as Al ( p 〈 0.01) concentrations in tree rings. April rainfall showed significant positive correlation with K and Zn ( p 〈 0.05) as well as Al ( p 〈 0.01) concentration in tree rings. The results suggest that tree rings from Chinese pine in Shenyang are sensitive to environmental change and have the potential to be used as a biomonitor for the environmental pollution. The results also demonstrate the feasibility of applying dendrochemical techniques to areas with limited samples.

Description: Available online 3 September 2012 Publication year: 2012 Source: Dendrochronologia To understand the effect of climate on tree-ring features, such as width or density, tree-ring data have to be calibrated against instrumental records. The high degree of multicollinearity among monthly time series of climate data violates the assumption of independent predictor variables in ordinary least squares regression. Bootstrapped confidence intervals of parameter estimates via regression against the principle components of the predictor variables are a possible solution to that problem. Package bootRes for R implements a flexible interface for bootstrapped response and correlation function analysis and tackles some shortcomings of currently available software. Given the increasing popularity of the free R software for statistical analysis, bootRes should facilitate both using R as a computational environment among tree-ring scientists and implementing new approaches to dendroclimatic calibration.

Description: Available online 23 September 2012 Publication year: 2012 Source: Dendrochronologia The opening of the Silk Road vigorously promoted economic and cultural exchanges between Central Asia, Europe, northern India and China. The easternmost section of the ancient trade route was established during the Qin-Han period (221 BC to 220 AD). Previous research has shown that there were three routes: the first is known as the “Hexi Route”, the second is known as the “Juyan Route” or “Prairie Route”, and the third is known as the “Qinghai Route”. The Qinghai Route has long been viewed as merely an auxiliary line of the Hexi Route which was used when the main Hexi Route was blocked by warfare. Others believe that the Qinghai Route was used during the 5th to 6th century when it was controlled by Tuyuhun Kingdom. Yet, by the 7th to 8th century, after the Tibetan occupation of the region, it was no longer a main trade route. Dendrochronology, the study of tree-rings, is a precise dating method that can be accurate to the year. In this study, wood remains excavated from tombs along the ancient Qinghai Route were studied by the means of dendrochronology in order to determine the date and better understand when Qinghai Route was used. In the tombs a lot of commercial goods such as silk products, pottery, lacquer carpentry were found. The date of the tombs determined by dendrochronology when viewed together with other archaeological data, showed that from the early Tang Dynasty to the High Tang Dynasty (early 7th century to late 8th century), the Qinghai Route was one of the routes of communication between the West and China. This disproves the hypothesis that this route was only used during the 5th to 6th century.

Description: Available online 25 August 2012 Publication year: 2012 Source: Dendrochronologia In dendrochronological dating, we encounter the trouble that some samples cannot be dated due to the occurrence of anomalies in the tree-ring series. When dating subfossil wood for the extension of existing master chronologies, this may be an especially unwanted circumstance as subfossil wood is scarce and each sample is valuable. In Moravia (Czech Republic) outbreaks of the cockchafer ( Melolontha sp.) used to appear with a disastrous effect on agricultural crops, and, for a dendrochronologist, on samples of wood to be dated. Oak ring width reduction caused by cockchafer induced defoliation can superimpose climate induced growth variations and may complicate dating of historical or subfossil samples. For this study, 33 samples of sub-fossil trunks were assessed; 19 of which were attacked by cockchafer. For comparison, we analysed a total of nine living oak trees from the forest district Strážnice-Vracov, recently attacked by the cockchafer. Occurrence of the cockchafer was reported there in 1999, 2003 and 2007. We found clear growth patterns with cyclic narrow rings every 4 years. This allowed us to create an artificial curve expressing the recurring cycles of cockchafer outbreaks which assisted us in the detection of the same pattern in subfossil tree growth. The tree-ring series of the attacked living oak stand as well as the 19 individual tree-ring series from subfossil oak trunks could not be dated using standard chronologies and showed a high resemblance to the cockchafer life cycle. Additionally, we found out that the living oak stand was attacked in 1983, 1987, 1991 and 1995 as well. The results support the hypothesis that the periodical reduction observed in tree-rings at regular increments is caused by cockchafer infestation. This evidence is further supported by characteristic anatomical features in early wood. A mean tree-ring series was created from the individual tree-ring series of subfossil oaks even though radiocarbon dating showed completely different ages of samples. This means that the affected tree-ring series cannot be used for dendrochronological dating and dendroclimatological analyses. These series cannot be used without preceding mathematical and statistical modification.

Description: Publication year: 2012 Source: Dendrochronologia Shuzhi Wang, Xiuhai Zhao The opening of the Silk Road vigorously promoted economic and cultural exchanges between Central Asia, Europe, northern India and China. The easternmost section of the ancient trade route was established during the Qin-Han period (221 BC to 220 AD). Previous research has shown that there were three routes: the first is known as the “Hexi Route”, the second is known as the “Juyan Route” or “Prairie Route”, and the third is known as the “Qinghai Route”. The Qinghai Route has long been viewed as merely an auxiliary line of the Hexi Route which was used when the main Hexi Route was blocked by warfare. Others believe that the Qinghai Route was used during the 5th to 6th century when it was controlled by Tuyuhun Kingdom. Yet, by the 7th to 8th century, after the Tibetan occupation of the region, it was no longer a main trade route. Dendrochronology, the study of tree-rings, is a precise dating method that can be accurate to the year. In this study, wood remains excavated from tombs along the ancient Qinghai Route were studied by the means of dendrochronology in order to determine the date and better understand when Qinghai Route was used. In the tombs a lot of commercial goods such as silk products, pottery, lacquer carpentry were found. The date of the tombs determined by dendrochronology when viewed together with other archaeological data, showed that from the early Tang Dynasty to the High Tang Dynasty (early 7th century to late 8th century), the Qinghai Route was one of the routes of communication between the West and China. This disproves the hypothesis that this route was only used during the 5th to 6th century.

Description: Publication year: 2012 Source: Dendrochronologia Pierre Mérian, Jean-Claude Pierrat, François Lebourgeois Regional chronology and climate–growth relationships assessment are known to be sensitive to sampling effort. To disentangle the respective benefits of increasing whether the number of plots or the number of trees per plot when investigating climate–growth relationships under temperate conditions, we propose to simulate samples from a set of 84 plots established in plantations of Corsican pine ( Pinus nigra Arnold ssp. laricio Poiret var. Corsicana ), within which 10 dominant trees were cored in 1992. The effect of sampling effort was investigated through 20 modalities of sampled plots (from 3 to 84) and 10 modalities of sampled trees per plot (from 1 to 10). Regional chronology was studied using the mean effective correlation and the expressed population signal, while climate–growth relationships were evaluated through correlation functions. The calculation of the correlation functions also allowed testing the effect of sampling effort on various climatic regressors presenting different climate–growth correlation strengths. The accuracy of the dendroecological investigations increased with increasing sample size: estimating climate sensitivity with a regional chronology built from a small sample led to a general under-estimation of the climate–growth correlations. Decreasing sample size also increased the risk of estimating (i) “false” non-significant correlations for the most influencing climatic regressors, and (ii) “false” significant correlations for the less influencing ones. Increasing the number of plots was found of a greater interest than increasing the number of trees per plot to improve the climate–growth relationships assessment. Finally, the analysis revealed that the improvement of the expressed population signal with increasing sampling effort did not linearly mirror the bettering in the climate–growth correlations assessment.

Description: Publication year: 2012 Source: Dendrochronologia Mingxing Cui, Xingyuan He, Nicole Davi, Zhenju Chen, Xianliang Zhang, Junjie Peng, Wei Chen In order to detect the response of trees to environmental pollution in Shenyang during the last century, tree rings of two 100+ year old Chinese pine ( Pinus tabulaeformis Carr.) were analyzed for nine trace element concentrations (K, Ca, Mg, Mn, Cu, Zn, Al, Pb and Cd) and compared to local environmental change. The concentrations of Cu, Zn and Al had significant ( p 〈 0.01) increasing trends after 1940s and correlated significantly ( p 〈 0.01), with increasing production of nonferrous metal from local industrial processing. Concentrations of nutrient element (K, Ca and Mg) showed significant ( p 〈 0.01) increasing trend from heartwood to sapwood with declines in the last three decades. Significant correlation between climatic factors and element concentration in tree rings were also found, in which the temperature (November to May) and relative humidity in April and May showed significant positive correlation with Ca, Zn and Cu ( p 〈 0.05) as well as Al ( p 〈 0.01) concentrations in tree rings. April rainfall showed significant positive correlation with K and Zn ( p 〈 0.05) as well as Al ( p 〈 0.01) concentration in tree rings. The results suggest that tree rings from Chinese pine in Shenyang are sensitive to environmental change and have the potential to be used as a biomonitor for the environmental pollution. The results also demonstrate the feasibility of applying dendrochemical techniques to areas with limited samples.

Description: Publication year: 2012 Source: Dendrochronologia M. Wilmking, M. Hallinger, R. Van Bogaert, T. Kyncl, F. Babst, W. Hahne, G.P. Juday, M. de Luis, K. Novak, C. Völlm Woody plants growing in seasonal climates normally form one growth ring each year. However, under severe stress conditions they may not complete annual wood production all the way down to the root collar resulting in continuously missing outer rings at lower stem sections (CMORs). Here we test whether CMORs occur at different distributional margins of woody plant species, where stress levels are expected to be high. We tested 13 species (202 individuals) of trees and shrubs growing at elevational and latitudinal shrub- and tree-lines, under conditions that are normally associated with a reduction of radial growth such as drought, cold or nutrient deficiency. Samples were collected from Alaska, north western Russia, Central Europe, Scandinavia and south eastern Spain. Annual radial growth was measured along several disks or cores of each individual applying the serial sectioning technique. Individuals of nine species showed CMORs. The proportion of individuals with CMORs within a sampled species and site ranged from 0% to 80%. The number of CMORs within an individual increased with decreasing sampling height on the stem. Significant correlations existed between the amount of CMORs and (i) cambial age, (ii) stem length, (iii) stem proportion/length below peat surface, and (iv) herbivore-caused defoliation intensity depending on the species and sampling location. Our results suggest that CMORs can be associated with a cambium that may be inactive, yet functional, for up to 18 years. We conclude that CMORs can occur in a wide variety of species, growth forms and biomes, suggesting a general strategy of woody plant growth. To avoid miss-dating in dendrochronological studies, we further recommend the use of the serial sectioning technique for woody plants growing in unfavorable environments, above all, when sample size is limited and when no established chronology for cross-dating is available.

Description: Publication year: 2012 Source: Dendrochronologia Martin Worbes, Nils Raschke The rising discussion on carbon balance of tropical forests often does not consider the sequestration potential of secondary dry forests, which are becoming an increasing importance due to land use change and reforestation. We have developed an easy applicable tool for the estimation of biomass increment of tropical secondary forest stands on the base of tree ring analysis. The existence of annual rings was shown by a combination of anatomical examination and radiocarbon estimations. With tree ring analysis, forest inventories and destructive sampling the above-ground biomass increment of secondary forest stands of age between 9 and 48 years in the dry forest region of Guanacaste, Costa Rica were estimated. The above-ground biomass increment of the tree layer varies between 2.4 and 3.2 Mg/ha yr in different stands. Lianas contribute with up to 23% additional production. Differences in productivity among the stands along a chronosequence were not significant. The measured carbon allocation potential of 1.7–2.1 Mg C/ha yr lies in the range of reported values from other tropical dry forests and old growth humid forests as well.

Description: Publication year: 2012 Source: Dendrochronologia D.M. Brown, M.G.L. Baillie In the course of building the 7000 year Belfast long oak chronology a series of depletion problems were encountered. These problems were overcome by 1984 when the completion of the Long Chronology was announced. The solution to the bridging of the various ‘gaps’ in the Irish chronology lay in the use of long sections of oak chronology from Britain. Now that a quarter of a century has elapsed and large numbers of additional oak samples, and site assemblages, have been accumulated it seems reasonable to review the ‘gaps’ in order to see if the Irish chronology could now be constructed without the use of British material. That is, are the depletion periods in the Irish chronology still evident, and if so, what might they imply about past conditions and human populations? The perhaps surprising conclusion is that the original depletions are still evident after 25 years of quasi-random sampling by archaeologists and palaeoecologists throughout Ireland.

Description: Publication year: 2012 Source: Dendrochronologia Nesibe Köse, Ünal Akkemik, Hasan Nüzhet Dalfes, Mehmet Sinan Özeren, Doğanay Tolunay Pinus nigra Arn. subsp. pallasiana (black pine) is one of the most widely grown tree in Turkey. It is the third most widely distributed tree species after Quercus L. and Pinus brutia Ten. Black pine grows in 20% of all forested areas in Turkey. In this dendroecological study, we identified the most important climate factors affecting radial growth of black pine in western Anatolia and classified its responses to climate. Twenty-eight site chronologies developed by different researchers were used in the analysis. Response functions were calculated for each chronology to identify the effect of climate on radial growth. Hierarchical cluster analysis was used to sort response functions and to classify the chronologies into groups based on climate responses. The individual responses of these chronologies to temperature and precipitation were classified in four main groups. Climatic and phytogeographic differences were the major factors influencing the formation of clusters. The results suggest that the major limiting factor is drought caused by low precipitation, especially in May, in almost all sites. The drought effect is much stronger in the transition region to the steppe, Central Anatolia and Mediterranean Regions than the Black Sea Region. Black pine trees respond positively to higher temperature at the beginning of growing season in almost all areas except in transition region to the steppe.

Description: Publication year: 2012 Source: Dendrochronologia Steen Magnussen, René I. Alfaro Aerial surveys provide valuable information on the scale and severity of defoliation and mortality caused by forest insects. However, methods to estimate the losses in growth using aerial survey data are not available. This study presents a method to link aerial survey data of location and severity of insect defoliation to tree ring series of radial growth in order to quantify potential growth losses due to defoliation. The method includes estimation of potentially confounding effects of climate. As an example we used aerial surveys of hemlock looper defoliation in the Mt. Revelstoke region of British Columbia, and tree ring series of radial growth of 351 western hemlock trees located in 22 plots and exposed to various levels of periodic defoliation. An autoregressive conditional heteroskedasticity time-series model (ARCH) of standardized growth indices identified significant direct and lagged effects of climate and defoliation on radial growth between 1930 and 2005. Defoliation effects were statistically significant in all plots ( P 〈 0.05). The variation in both timing and strength of estimated growth reductions varied considerably among plots. During years of observed defoliation the radial growth was reduced by an average of 10%. Growth reductions attributed to defoliation were most pronounced in the second and third year of a looper outbreak. Our modelling approach linked tree ring data to aerial survey data of defoliation through a logistic distance dependent threshold function and affords a quantitative estimation of regional growth losses.

Description: Publication year: 2012 Source: Dendrochronologia Marina Gurskaya, Martin Hallinger, Jayendra Singh, Leonid Agafonov, Martin Wilmking Tree core samples of larch ( Larix sibirica Ledeb.), spruce ( Picea obovata Ledeb.) and pine ( Pinus sibirica Du-Tour.) from the northern taiga of West Siberia were collected to assess their potential for summer temperature reconstructions in the Ob River region. Bootstrapped response functions showed that annual growth was mainly influenced by May to June temperatures in pine and by June to July temperatures in spruce and larch. Spruce and pine chronologies showed high positive correlations with previous October temperature. June–July temperatures were reconstructed based on spruce (1795–1996) and larch (1615–1999) tree ring chronologies. The pine chronology could not be used for a reliable temperature reconstruction, due to low values of explained May–June temperature variance (11–15%) but the species has a high potential to help clarify the May–June and October climatic influence on ring width observed in all three species. We explained the effect of the early vegetation period (May–July) and the differences in the temperature signals between spruce and larch tree ring chronologies with the influence of previous September and October temperature on tree growth with the warming effect of the Ob River and differences of the species’ photosynthetic possibilities and the activity of chloroplasts and bud meristem tissues.

Description: Publication year: 2012 Source: Dendrochronologia Christian Zang, Franco Biondi To understand the effect of climate on tree-ring features, such as width or density, tree-ring data have to be calibrated against instrumental records. The high degree of multicollinearity among monthly time series of climate data violates the assumption of independent predictor variables in ordinary least squares regression. Bootstrapped confidence intervals of parameter estimates via regression against the principle components of the predictor variables are a possible solution to that problem. Package bootRes for R implements a flexible interface for bootstrapped response and correlation function analysis and tackles some shortcomings of currently available software. Given the increasing popularity of the free R software for statistical analysis, bootRes should facilitate both using R as a computational environment among tree-ring scientists and implementing new approaches to dendroclimatic calibration.

Description: Publication year: 2012 Source: Dendrochronologia Tomáš Kolář, Michal Rybníček, Willy Tegel In dendrochronological dating, we encounter the trouble that some samples cannot be dated due to the occurrence of anomalies in the tree-ring series. When dating subfossil wood for the extension of existing master chronologies, this may be an especially unwanted circumstance as subfossil wood is scarce and each sample is valuable. In Moravia (Czech Republic) outbreaks of the cockchafer ( Melolontha sp.) used to appear with a disastrous effect on agricultural crops, and, for a dendrochronologist, on samples of wood to be dated. Oak ring width reduction caused by cockchafer induced defoliation can superimpose climate induced growth variations and may complicate dating of historical or subfossil samples. For this study, 33 samples of sub-fossil trunks were assessed; 19 of which were attacked by cockchafer. For comparison, we analysed a total of nine living oak trees from the forest district Strážnice-Vracov, recently attacked by the cockchafer. Occurrence of the cockchafer was reported there in 1999, 2003 and 2007. We found clear growth patterns with cyclic narrow rings every 4 years. This allowed us to create an artificial curve expressing the recurring cycles of cockchafer outbreaks which assisted us in the detection of the same pattern in subfossil tree growth. The tree-ring series of the attacked living oak stand as well as the 19 individual tree-ring series from subfossil oak trunks could not be dated using standard chronologies and showed a high resemblance to the cockchafer life cycle. Additionally, we found out that the living oak stand was attacked in 1983, 1987, 1991 and 1995 as well. The results support the hypothesis that the periodical reduction observed in tree-rings at regular increments is caused by cockchafer infestation. This evidence is further supported by characteristic anatomical features in early wood. A mean tree-ring series was created from the individual tree-ring series of subfossil oaks even though radiocarbon dating showed completely different ages of samples. This means that the affected tree-ring series cannot be used for dendrochronological dating and dendroclimatological analyses. These series cannot be used without preceding mathematical and statistical modification.

Description: Publication year: 2012 Source: Dendrochronologia, Volume 30, Issue 3

Description: Publication year: 2012 Source: Dendrochronologia Donald K. Youngblut, Brian H. Luckman We present a network of thirteen annual ring-width chronologies from high elevation whitebark pine ( Pinus albicaulis Engelm.) sites in the western Canadian Cordillera in order to assess the dendroclimatic potential of this long-lived tree species. The temperature signal within the chronologies is complex and strongly influenced by diverging trends in the summer temperature and ring-width records from across the region. A first differences transformation of the tree-ring and temperature records illustrates a loss of frequency coherence in growth response to summer temperatures following reduced radial growth in the 1950s. Prior to reduced growth, we note a positive association with summer temperatures for both first differenced ( r d = 0.60) and traditional ( r = 0.50) records. Following reduced growth, the association at first differences is maintained ( r d = 0.49) whereas there is a change in the lower frequency component of tree growth response to summer temperatures ( r = −0.34). We suggest the cause of this reduced temperature sensitivity is related to the interaction between diurnal temperature and cloud cover patterns, the hydrological regime of snowpack, and site conditions which have been amenable to the initiation of moisture stress during the latter half of the 20th century. Reduced radial growth is coincident with the arrival of white pine blister rust ( Cronatium ribicola J.C. Fisch. ex Raben) into the study region which suggests this infestation may be related to the observed reduction in radial growth. Whitebark pine has considerable potential for the field of dendroclimatology. Unfortunately, the decline of the species due to the combined effects of climate change, white pine blister rust, mountain pine beetle ( Dendroctonus ponderosae Hopk.), and forest fire exclusion practices indicate this potential may remain unfulfilled.

Description: Publication year: 2012 Source: Dendrochronologia Ana I. García-Cervigón Morales, José Miguel Olano Mendoza, Màrcia Eugenio Gozalbo, J. Julio Camarero Martínez In contrast to most high elevation areas, plant growth at Mediterranean mountains is exposed to a summer drought period, which represents an additional climatic constraint to low temperatures. Although arboreal and shrubby conifers coexist at high altitudes, most dendroecological studies have focused on climatic responses of tree species, whereas those of shrubby species remain mostly unexplored. We built tree-ring width chronologies for two conifer species, a shrub ( Juniperus sabina ) and a tree ( Pinus sylvestris ), coexisting at three high-altitude localities of the Iberian System mountains, eastern Spain. We analyzed their climate–growth relationships for the period 1950–2009 using correlation analyses and multiple regressions. Coexisting species responded to year-to-year climatic variability in different ways. Radial growth in junipers and pines responded positively to April and May temperatures, respectively. Summer drought constrained growth in both cases, although its impact was stronger on junipers than on pines. Our findings suggest that junipers respond earlier than pines to spring temperatures due to their prostrate morphology which may enhance a fast warming of their cambial meristems after snowmelt. The higher dependence of J. sabina on summer rainfall as compared with co-occurring pines confirms that drought stress negatively impacts secondary growth in Mediterranean mountains. This sensitivity to water availability may be caused by the juniper shallow root systems, which mainly use superficial soil water. The climatic signal registered in J. sabina allows studying the response of other similar shrubby woody species growing in Mediterranean alpine areas to the ongoing climate warming, which could also reduce water availability.

Description: Publication year: 2012 Source: Dendrochronologia Esther Jansma, Rowin J. van Lanen, Peter W. Brewer, Rutger Kramer Existing on-line databases for dendrochronology are not flexible in terms of user permissions, tree-ring data formats, metadata administration and language. This is why we developed the Digital Collaboratory for Cultural Dendrochronology (DCCD). This TRiDaS-based multi-lingual database allows users to control data access, to perform queries, to upload and download (meta)data in a variety of digital formats, and to edit metadata on line. The content of the DCCD conforms to EU best practices regarding the long-term preservation of digital research data.

Description: Publication year: 2012 Source: Dendrochronologia Santosh K. Shah, Amalava Bhattacharyya This research aimed to evaluate spatio-temporal growth variability of three Pinus species viz. Pinus kesiya (Khasi pine), Pinus merkusii (Merkus pine) and Pinus wallichiana (Blue pine) along with the existence of species differentiation among the taxa in northeast India. Several statistical analyses were used, namely Pearson correlation and multivariate approaches involving UPGMA Cluster Analysis; ordination methods by Principal Component Analysis (PCA) and Non-metric multidimensional scaling (NMDS) on tree-ring width chronologies from 13 sites. The tree growth-climate relationships were assessed with both correlation and bootstrap response function using regional climate datasets of each sampling site prepared by averaging the nearest grid points of 0.5 × 0.5° of CRU TS-2.1 climate dataset. Pronounced species differentiation in the growth pattern among the three Pinus taxa was inferred. The observed spatio-temporal variability revealed inter-species tree growth variations were not uniform suggesting no common factor influenced the radial tree growth in this region, which may be related to anthropogenic impact or non-climatic factors. The tree growth-climate relationship showed that climatic factors limiting the radial growth of Pine are mostly similar for intra-species but diverse in inter-species. This study is extremely relevant in terms of species and site selection for the long-term climate reconstruction and forest management in the Northeast Himalaya.

Description: Publication year: 2012 Source: Dendrochronologia Julia Krepkowski, Achim Bräuning, Aster Gebrekirstos Podocarpus falcatus is an indigenous evergreen conifer species of tropical mountain forests in southeastern Ethiopia, showing potential tree ages of around 500 years. To study the influence of seasonal climate on the growth pattern of P. falcatus , we combined high-resolution electronic dendrometer measurements with wood anatomical investigations of microcores from the outermost stem parts collected in monthly intervals. At any time of the year sufficient rain events are able to cause cambial activity in P. falcatus . This permanent growing readiness leads to irregular wood formation with the formation of intra-annual density fluctuations and missing rings. Wood anatomical studies of microcores collected around the circumference of a mature P. falcatus revealed locally different activity status of the cambium on different lobes of the stem. Tree-ring width measurements of stem disks resulted in tentative tree ages that were confirmed by radiocarbon dating of selected wood samples. Although our efforts to cross-date ring-width series from several stem disks were not successful, further sampling in areas with different rainfall regimes, additional radiocarbon dating and measurements of stable isotopes hopefully would enable the establishment of a multi-century-long tree-ring series for climate reconstruction.

Description: Publication year: 2012 Source: Dendrochronologia David M. Cairns, Charles W. Lafon, Michelle F. Mouton, Rachel L. Stuteville, Amanda B. Young, Jon Moen The annual growth rings of diffuse porous species such as mountain birch are often difficult to distinguish when samples are collected from trees that grow at treeline or in other harsh environments. In this study we document the differences in seedling and sapling ring counts obtained from two methods of analysis: a traditional analysis based on reflected light and low-power microscopy and one based on transmitted light with higher power magnification that uses thin-sections of the samples. Rings are easier to resolve using the more labor-intensive transmitted light method. Small rings are often missed when using the reflected light method, resulting in an underestimation of tree age. The dates estimated by the standard method agreed with those determined using the thin-sectioning method in 9.6% of the cases. Most commonly, the standard method gave a younger age than did thin-sectioning (72.4% of the trees). In only 18.03% of the cases did the standard method result in a greater age than did thin-sectioning. The reflected light method produced age estimations that were on average 1.37 years younger than those determined using the transmitted light method. The difference between the two methods was positively correlated with age and negatively correlated with mean ring-width. Age-class histograms based on the two methods show little difference at coarser aggregation levels (decades and pentads), but annualized age-class histograms have less agreement between the two methods. Therefore, we suggest using the more labor-intensive thin-sectioning method when annualized age counts are necessary in suppressed seedlings and saplings, for example, comparing tree establishment with annual climate conditions at treeline.

Description: Publication year: 2012 Source: Dendrochronologia Tomáš Kolář, Tomáš Kyncl, Michal Rybníček A prerequisite for successful dating of wooden archaeological finds and historic wooden constructions in a specific territory is the existence of a chronology. In the Czech Republic the species most frequently dated by dendrochronology is oak ( Quercus spp.). There are two territories where oak forests can be found (Bohemia and Moravia/Silesia), which are divided by an area without oak – the Highlands (Vysočina). The previous oak chronology for the Czech Republic from 2005 was extended in 2010, and currently we have a discontinuous oak chronology (CZGES 2010) ranging from 4682 bc to 2006 ad with a large sample size between 760 ad and the present. When comparing this chronology with European chronologies, the highest degree of similarity has been observed with chronologies for Eastern Austria, most of Germany and the Polish part of South Silesia. When comparing the chronologies for Moravia/Silesia (MORGES 2010) and Bohemia (CECHGES 2010) separately with chronologies from the Pannonian Basin, the Moravian/Silesian chronology manifests higher degrees of similarity. The Czech oak chronology enlarges the European network of chronologies, which is necessary for dendroarchaeological applications mainly.

Description: Publication year: 2012 Source: Dendrochronologia Trevor J. Porter, Paul Middlestead Stable isotope dendrochronology is a well-developed field of research, but improvements to methodologies are on-going. We propose an improved method for estimating the precision of stable isotope ratios ( δ ) of tree-ring samples that are processed from whole wood to various end products such as cellulose-nitrate, α-cellulose, or cellulose intermediates. The status quo method for estimating the δ precision of organic solids is to characterise the long-term 2-sigma range of δ values for a ready-made Quality Assurance (QA) standard that is included in each analysis run of samples. While the status quo method is appropriate for characterising analytical uncertainties associated with the mass spectrometer, combustion or pyrolysis system, and analyte specifics, it does not reflect uncertainties associated with sample processing from inadvertent and unrealised operator error (e.g., contamination by airborne particles, incomplete chemical processing, sample storage issues, and other unforeseen errors), although such errors would probably be rare with an experienced operator. The proposed method improves upon the status quo method as it respects the Identical Treatment principle by subjecting QA standards to the same processing steps that samples undergo. As such, analytical uncertainties associated with sample processing would be integrated into the QA standard's δ value and precision estimate. In effect, the proposed method is a system to monitor inter-batch reproducibility and, by the same token, can be used to identify batches that were potentially compromised during processing. A pilot study example is used to demonstrate the proposed method for δ 18 O analysis of α-cellulose samples.

Description: Publication year: 2011 Source: Dendrochronologia, Available online 15 November 2011 Jorge Olivar, Stella Bogino, Heinrich Spiecker, Felipe Bravo Mediterranean environments are of special interest for the study of the relationships between climate, growth and anatomic features. Dendrochronological techniques were applied at eight sampling sites that were selected throughout the natural distribution area ofPinus halepensisin the Iberian Peninsula. The objectives of this paper were: (i) to identify relationships between radial growth and climate for different crown classes of Aleppo pine (P. halepensisMill.); (ii) to quantify the presence of intra-annual density fluctuations (IADFs) according to crown class and cambial age; (iii) to establish the relationships between IADFs and climate. In the more mesic sites, dominant trees showed higher climatic sensitivity than suppressed trees, while in the more xeric sites suppressed trees showed higher sensitivity than dominant trees. Tree-ring growth of both crown classes correlated positively with precipitation during and prior to the growing season. IADFs were more frequent in young than in old stands without differences between crown classes. Precipitation in April and December was positively correlated to the occurrence of IADFs, while precipitation in July correlated negatively. A higher frequency in IADFs occurred in the last 50 years, which coincides with the increase in drought events in the Iberian Peninsula.

Description: Publication year: 2011 Source: Dendrochronologia, Available online 17 November 2011 Kristof Haneca, Vincent Debonne A detailed dendrochronological survey was performed on the medieval roofs of the Church of Our Lady (CoOL) in Damme, Belgium. Seen its complex architectural history, special attention was paid to the identification of consecutive building phases, based on combined architectural historical research and tree-ring dating. In total 64 increment cores were taken throughout the roof structures of the CoOL. All roof timbers are made of European oak (Quercus robur/petraea), of which only few have surviving sapwood or bark. Tree-ring dating confirms the late 13th/early 14th century construction date of the roofs. For all chronologies that were composed, the highest correlation values are found with reference chronologies covering the catchment area of the river Meuse. From the dating results of the timbers of the CoOL it becomes clear that the same timber source was used for nearly a century. On several of the examined roof timbers, rafting joints were observed, demonstrating that the timbers were indeed tied together as a raft and floated down the river.By implementing sapwood estimates in a Bayesian chronological model (OxCal), tree-ring series with surviving sapwood from coeval roof structures were combined in order to narrow down the time range for the felling date. Based on the refined interpretation of the felling dates, several consecutive building phases can now be identified and dated, leading to a new interpretation of the architectural history of the CoOL. Intriguingly, a marked interruption in building activities is observed around 1300. Probably this is related to the instable political situation at that time, caused by the armed conflict that emerged between the Count of Flanders and the king of France. Since Damme served as the outport of the riotous city of Bruges, it was alternately seized by the French and Flemish, both consuming considerable amounts of timber and other building materials for military fortifications. Potentially this led to a shortage in building materials and provoked a stop in building activities.This paper demonstrates the power of Bayesian models to refine the interpretation of dendrochronological dates in architectural analyses of medieval historical buildings.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 28 February 2012 Keyan Fang, Xiaohua Gou, Fahu Chen, Yingjun Li, Fen Zhang, ... Individual tree-ring series may show changed growth trends and divergent climate–growth associations even within a site, highlighting the need to examine tree growth and its climate association before building a chronology. We provided a case study for the stratification and temporal variability of tree growth and its climate associations of individual cores for three mountain ranges in north central China. Tree growth is mainly limited by moisture conditions in previous July–September and current June–August. Repeated sampling and field investigations ofPicea wilsoniiat Xinglong Mountain over a growth year of 2004 suggested that the growing season is from about the end of April to the end of September. It appears that the moisture conditions in previous and current growing seasons are crucial for tree growth in this region. However, a decrease in drought limitation was observed for a few tree-ring series. We thereby built the pooled chronology and sub-site chronologies with only drought-sensitive tree rings similar climate–growth relationships from the three mountain slopes. Growth disturbances of tree-ring series are detected by checking the occurrence of successively low values of the biweight series, which are treated by fitting a flexible curve.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 23 February 2012 Hannu Hökkä, Hannu Salminen, Erkki Ahti The climate conditions of the current and previous growing seasons have been shown to influence growth of coniferous trees in mineral soils sites. These dependencies may be different in peatlands where growth is generally more dependent on variations in soil water conditions. In the Nordic and Baltic countries, millions of hectares of peatlands and wetlands have been drained in order to enhance forest production. These drainage networks do not guarantee stable soil water conditions for the whole stand rotation. It is thus likely that precipitation in particular may have a different influence on annual growth in peatland to that in mineral soil sites. We studied the effect of precipitation and temperature on the inter-annual diameter growth of Scots pine (Pinus sylvestrisL.) in Finland in drained peatland forests. The diameter growth data were limited to periods when growth response to drainage had levelled out. For comparison, growth data were also collected from adjacent mineral soil trees. The climate variables were monthly mean temperature and precipitation in a given location estimated from observations at the nearest weather stations by means of spatial smoothing. We used mixed linear models in describing the annual diameter growth of individual trees as a function of tree size and stand properties and expressed the residual variation as a function of climate parameters. The peatland and mineral soil growth variations showed different dependence on climate parameters. Peatland trees within 5 m of a ditch showed different climate responses compared to those located further away. Precipitation in July was negatively correlated with the diameter growth of peatland trees but there was no correlation with temperature. Growth of trees in mineral soils was positively correlated with March and April mean temperatures and May and June mean precipitation. The residual growth indices showed largely similar patterns in peatlands and mineral soil sites.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 17 February 2012 Christoph Dittmar, Thomas Eißing, Andreas Rothe Tree-ring (TR) chronologies are important instruments for the dating and provenance analyses of historical wood, as well as for climate reconstructions. However, radial growth patterns differ between tree species and growing environments. Therefore chronologies are more or less specific for a certain tree species, region and elevation. Chronologies that are restricted to more confined regions could extend the possibilities for dating, dendroprovenancing and regional climate reconstructions.In Southern Germany, the transport of wood by raft – for the supply of towns and cities with timber – has been documented since early mediaeval times. Consequently, not only local timber from the lowlands was used for construction purposes, but also alpine wood originating from sites up to the timberline. Since pronounced altitudinal gradients cause distinct climate differences, elevation-specific chronologies have the potential to improve dating precision in this region.In this contribution, a model is presented and applied in order to separate elevation-specific provenances of Norway spruce (Picea abiesL. Karst) and Silver fir (Abies albaMill.) in Southern Germany. The model is derived from more than 2100 living TR series originating from sites between 200 and 1710 m above see level. Absolute (mean, maximum) ring-width values and the variation of ring-widths (mean sensitivity) show distinct correlations with their altitudinal provenance, reflecting improvements in growth conditions as well as the increase of their yearly variation from high over intermediate to low elevation sites. Mean ring widths and mean sensitivity values were used as independent parameters in an exponential regression model which exhibits a coefficient of determination (r) of 77% for spruce and 74% for fir. The prediction accuracy of the elevation amounts ±300 m for spruce and ±200 m for fir within the 95% confidence interval.The model was used to estimate the elevation origin of around 5000 historical spruce and 800 historical fir series from buildings located in Southern Germany. The historical TR series covering the AD 990–1800 period were allocated by the model to elevations between 120 and 2090 m. In a second step the individual TR series were combined to elevation-specific chronologies representing low, intermediate, and high altitudinal belts. The chronologies show distinct differences among the altitudinal belts in terms of signatures and pointer years, especially for spruce. Elevation-specific chronologies are assumed to amplify the dating possibilities of ancient timber, to provide valuable evidences for the origin of historical wood, and to offer more specific proxy data for regional climate reconstructions.

Description: Publication year: 2011 Source: Dendrochronologia, Available online 24 October 2011 Rob Wilson, C. Richard Bates Following the successful utilisation of lake preserved sub-fossil woody material to extend living Scots pine chronologies in Scandinavia, ongoing research in the Scottish Highlands aims to build a similar multi-millennial long climatically sensitive pine chronology. This paper details explorative research testing the use of sonar methods to facilitate the search for sub-fossil material in lake environments. Although the method clearly identifies elongate anomalies that are consistent with submerged tree stems in water depths 〉1.5 m, it does not allow the identification of sub-fossil wood remnants in shallow water (〈1.0 m) or heavily vegetated bays. Therefore, for the successful survey of lakes, a combination of traditional and sonar methods must be applied. Ongoing research will now explore the utilisation of these methods to more remote locations where boat access is not possible.

Description: Publication year: 2011 Source: Dendrochronologia, Available online 27 October 2011 Kristina Sohar, Adomas Vitas, Alar Läänelaid Pedunculate oak (Quercus roburL.) is one of the widely used and dendrochronologically investigated species in Europe. Still, it is a problematical dating object if its outermost section is missing partly or totally. Thus, we need sapwood estimation of living trees. As sapwood amount varies geographically, numbers of sapwood rings have been published for different regions in Europe but no such estimation has been done for the Baltic States yet. Therefore, this paper deals with the estimation of pedunculate oak sapwood growing in the eastern Baltic region, i.e. in Finland, Estonia, Latvia, and Lithuania.In total, 668 oak core samples of living trees from 43 stands were investigated. Ring widths were measured and the number of sapwood rings was determined according to two criteria: difference of colour and absence of tyloses in earlywood vessels. The samples were divided into two sets, according to thetH-values between site chronologies and the major geobotanical sub-provinces. Thus, the nine Finnish and western Estonian sites were attributed to the western region and the 34 eastern Estonian, Latvian and Lithuanian sites to the eastern region.As the result of a statistical analysis, we explain that the number of oak sapwood rings ranges from 4.09 to 20.85 and 6.45 to 18.02 within 95% confidence limits in the western and eastern regions, respectively. For the three Baltic countries and southern Finland in general, we recommend to consider a sapwood estimate of 6.18–18.71 rings. Regarding earlier studies, the general European trend of decreasing sapwood ring number towards the east was confirmed. A geographical pattern of eastward decrease of the median sapwood ring number was noticed in the Baltics as well. The chronology based upon 668 samples of living oak trees from all sites covered the period of 1631–2008.

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 22 March 2011 Yongxiang, Zhang , Xuemei, Shao , Martin, Wilmking Knowledge of the spatial pattern and temporal relationships between tree-growth and climatic factors are important not only for the projection of forest growth under varying climate but for dendroclimatology in general. Here, we systematically investigated tree-growth climate relationships of Picea crassifolia at upper treeline in the Qilian Mts., northwestern China. 297 trees from eleven sites, covering a large part of the natural range of this species, show increasing and partly divergent correlations with temperature in the most recent decades. The dominant signal at all sites was a strengthening of negative correlations of annual radial growth with summer temperature. In a...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 22 February 2011 Martin, de Luis , Klemen, Novak , José, Raventós , Jožica, Gričar , Peter, Prislan , ... Research was carried out on the wood formation process and the intra-annual density fluctuations (IADFs) in Mediterranean Aleppo pine (Pinus halepensis Mill.) trees from the coastal site of Guardamar, and inland Maigmo in south-eastern Spain. Samples taken at breast height of the trees were inspected to define the frequency of tree rings with latewood-like cells in earlywood (E-ring) and with earlywood-like cells in latewood (L-ring). L-rings were generally more frequent, especially on the warmer, dryer, coastal site of Guardamar. Dendrochronological techniques using tree-ring features vs. climate showed that L-rings were formed in Guardamar when August and/or September precipitation was higher...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 2 March 2011 Ute, Sass-Klaassen , Clifton R., Sabajo , Jan, den Ouden The earlywood–vessel area of ring-porous species is related to environmental factors that prevailed during the time of vessel formation. However, limited knowledge is available on the time window during which environmental factors such as temperature, precipitation or flooding can be recorded in vessel area. The susceptibility of vessel area to capture these environmental signals is likely to be related to the timing and duration of vessel formation. Ring-porous species are known to have their new earlywood vessels formed before buds break to guarantee efficient water transport through the large earlywood vessels in the outermost tree ring. However, as leaf phenology...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 2 March 2011 Jožica, Gričar , Cyrille B.K., Rathgeber , Patrick, Fonti

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 25 March 2011 [No author name available]

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 23 March 2011 B., Wagner , H., Gärtner , S., Santini , H., Ingensand Ring width of a given year can be highly variable throughout the cross section of a stem. This is especially true for roots. Therefore, the entire circumference of tree rings is often needed for studies focusing on specific reactions of individual trees on certain environmental conditions. Also, ring reconstructions are of interest for biomass calculations estimated by the cross-sectional area. The aim of the study is thus to reconstruct tree rings of cross sections within a 3D root-surface model, which will be the basis for an upcoming 3D root-development model. A FARO ScanArm was used for the acquisition of the...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 24 March 2011 R. Stockton, Maxwell , Joshua A., Wixom , Amy E., Hessl Crossdating is the core principle of dendrochronology. Our study compared two techniques for measuring and crossdating tree rings using Juniperus virginiana L. (eastern redcedar) as a case study. We used a pseudo 2×2 study design comparing the traditional skeleton plot/sliding measuring stage technique to a semi-automatic image analysis program across two technicians. Crossdating was evaluated in COFECHA. Raw measurements of total, earlywood, and latewood widths from the two methods were analyzed using the Verify for Windows program, ANOVA, and correlation matrices. Total ring width and earlywood width were well correlated between techniques and technicians but questionable ring boundaries from image...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 17 February 2011 Annie, Deslauriers , Sergio, Rossi , Audrey, Turcotte , Hubert, Morin , Cornélia, Krause Continuous measurements of stem radius variation in trees are obtained with automatic dendrometers that provide time series composed of seasonal tree growth and circadian rhythms of water storage and depletion. Several variables can be extracted from the raw data, such as amplitude and duration of radius increase and contraction, which are useful for understanding intra-annual tree growth, tree physiology and for performing growth–climate relationships. These measurements constitute a large dataset whose manipulation needs numerous algorithms and automatic procedures to efficiently and rapidly extract the information. This paper presents a three-step procedure using two SAS routines to extract the time series...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 16 February 2011 H., Vavrčík , V., Gryc The processes of xylogenesis are very often studied with use of repeated micro-sampling method. Microcores are taken throughout the growing season. After paraffin embedding and cutting on a rotary microtome permanent microslides are prepared. The numbers of cells (tracheids) are counted for each of the three zones – radially enlarging (G), maturing (D) and matured (T) zone of the developing growth ring. These numbers of cells are an input for the R script named WCDcalc that was developed for the calculation of durations and timing of cell differentiation in developing growth rings of softwoods. WCDcalc produces a plain text file...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 16 February 2011 Alessio, Giovannelli , Giovanni, Emiliani , Maria Laura, Traversi , Annie, Deslauriers , Sergio, Rossi This paper describes a procedure to analyze non-structural carbohydrates (NSC) and starch in xylem and cambial region extracted by the scraping method. An application on woody logs of 2-year-old Populus×canadensis Mönch ‘I-214’ during tree-ring formation is reported. Samples are freeze-dried in liquid nitrogen and, successively, the bark is removed. After drying, the breaks between bark and xylem take place in correspondence of differentiating xylem cells. The cambial region with the differentiating phloem and xylem is gently scraped with a razor blade from the inner side of the bark and the outermost side of the stem, respectively. Additionally the mature xylem...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 18 February 2011 Jean-Daniel, Bontemps , Jan, Esper Dendrochronological methods have greatly contributed to the documentation of past long-term trends in forest growth. As these methods primarily focus on the high-frequency signals of tree ring chronologies, they require the removal of the ageing trend in tree growth, known as ‘standardisation’ or ‘detrending’, as a prerequisite to the estimation of such trends. Because the approach is sequential, it may however absorb part of the low-frequency historical signal.In this study, we investigate the effect of a sequential and a simultaneous estimation of the ageing trend on the chronology of growth. We formerly developed a method to estimate historical changes in...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 16 February 2011 Katarina, Čufar , Martina, Cherubini , Jožica, Gričar , Peter, Prislan , Stefano, Spina , ... Cambial activity and the dynamics of xylem and phloem formation were monitored during the 2008 growth season in five chestnut (Castanea sativa) trees growing near Viterbo, Italy. The study was based on microscopic observations of micro-cores taken from stems at weekly intervals from mid-April until mid-October 2008. These observations allowed us to identify the timing of xylem and phloem formation. Cambial divisions, xylem and phloem formation had already started before the first sampling. By the end of April, the first earlywood vessels were already lignified and in early phloem the first formed sieve cells had finished postcambial growth. Formation of...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 17 February 2011 Cyrille B.K., Rathgeber , Fleur, Longuetaud , Frédéric, Mothe , Henri, Cuny , Gilles, Le Moguédec Studies of intra-annual dynamics of cambial activity and wood formation share very similar data because they are based on classic concepts of xylem development and well-documented techniques of sample preparation. However, the way the data are produced is specific to each study or group of authors because there is not a real agreement or consensus about critical variable definitions and data processing. The consequence is that despite very similar data, these studies are difficult to compare. In order to improve this point, we proposed objective definitions of the main phenological events (critical dates) occurring during wood formation, i.e. the beginning...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 22 January 2011 Thomas, Wieloch , Gerhard, Helle , Ingo, Heinrich , Michael, Voigt , Philipp, Schyma A novel device for the chemical isolation of α-cellulose from wholewood material of tree rings was designed by the Potsdam Dendro Laboratory. It allows the simultaneous treatment of up to several hundred micro samples. Key features are the batch-wise exchange of the chemical solutions, the reusability of all major parts and the easy and unambiguous labelling of each individual sample. Compared to classical methods labour intensity and running costs are significantly reduced.

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 20 July 2011 Keith L., McDougall , Matthew T., Brookhouse , Linda S., Broome Developing an understanding of the impact of climate on Australia's alpine flora is critical in anticipating the impacts of climate change. The dendroclimatological analysis of the Australian mainland's only alpine conifer, Podocarpus lawrencei Hook.f., may have particular significance in this regard. Unfortunately, eccentric tree-ring widths and frequent ring wedging have previously prevented dendroclimatic investigation of the species using core samples. In this study, we overcome this limitation by using full stem cross-sections collected from individuals killed during wildfire in 2003. Despite this advantage, ring wedging and poor circuit uniformity meant that crossdating was successful for portions or complete sections of...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 26 May 2011 S., Szymczak , M.M., Joachimski , A., Bräuning , T., Hetzer , J., Kuhlemann Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope–climate relationships. This study focuses on wood of Corsican Pine trees (Pinus nigra ssp. laricio) as this tree species allows to reconstruct the long-term climate evolution in the western...

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 7 January 2011 Rashit, Hantemirov , Stepan, Shiyatov , Ludmila, Gorlanova For the first time, Siberian juniper (Juniperus sibirica Burgsd.) has been dendroclimatologically analyzed. Siberian juniper is a small shrub growing in the larch-forest – tundra ecotone in Polar Urals. The 636-year juniper ring-width chronology presented here is based on samples prepared from living and dry branches. Here we prove that this chronology is suitable for dendroclimatic reconstructions. The juniper chronology contains a mean May, June and July temperature signal in contrast to June–July signal in spruce and larch ring-widths. Dendroclimatic reconstructions can be based on Siberian juniper chronology as well as on combined juniper and larch chronology.

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 15 January 2011 S.R., Managave , M.S., Sheshshayee , R., Ramesh , H.P., Borgaonkar , S.K., Shah , ... Results of interannual variations in cellulose oxygen isotopic composition (δ18O) of four teak (Tectona grandis L.F.) trees (one from western India, two from central India and one from southern India) are presented. Cellulose δ18O of teak trees from western and central India show a significant positive correlation with the amount of rainfall, which is contrary to expectation. We propose that this correlation is caused by longer duration of the growing season in years of higher rainfall. Teak from southern India shows a significant negative correlation with the amount of rainfall and this relationship is used to reconstruct rainfall back to...

Description: Publication year: 2011 Source: Dendrochronologia, Volume 29, Issue 1, 2011, Page 65 [No author name available]

Description: Publication date: Available online 10 December 2013 Source: Dendrochronologia Author(s): Inga Labuhn , Valérie Daux , Monique Pierre , Michel Stievenard , Olivier Girardclos , Anaïs Féron , Dominique Genty , Valérie Masson-Delmotte , Olivier Mestre A main concern of dendroclimatic reconstruction is to distinguish in the tree ring proxy the influence of the climate variables of interest from other controlling factors. In order to investigate age, site and climate controls on tree ring width and cellulose δ 18 O, measurements have been performed in nearby groups of young (145 years old) and older (310 to 405 years old) oak trees in south-western France, covering the period 1860-2010. Within a given site, inter-tree deviations are small, pointing to a common climatic signal. Despite a similar inter-annual variability, the average level of cellulose δ 18 O in the young tree group is ∼0.8‰ higher than in the old trees. Such offsets might be caused by different soil properties and differences in the fraction of the source water used by trees from different depths. The δ 18 O of water in the top soil layer is directly related to the current growing season precipitation, while deeper water can have a lower and more constant δ 18 O. Local cave drip waters at 10 m depth indeed show a constant isotopic composition, which corresponds to pluri-annual mean precipitation. A 2‰ increasing trend is observed in cellulose δ 18 O of young trees in the first 30 years of growth, during a period when no trend is visible in older trees. This increase can be quantitatively explained by humidity gradients under the forest canopy, and a changing microclimate around the crown as trees grow higher. While relationships between tree ring width and climate appear complex, the isotopic composition of cellulose is strongly correlated with summer maximum temperature, relative humidity and evapotranspiration (r ≈ 0.70). Weaker correlations (r ≈ 0.40) are identified with precipitation δ 18 O from a 15-year long local record and from the REMOiso model output. These results imply that leaf water enrichment has a stronger control on the inter-annual variability of cellulose δ 18 O than the δ 18 O of precipitation. This study demonstrates the suitability of oak tree ring cellulose δ 18 O for reconstructing past summer climate variability in south-western France, provided that the sampling and pooling strategy accounts for the fact that trees from different sites and of different age can introduce non-climatic signals.

Description: Publication date: Available online 11 January 2014 Source: Dendrochronologia Author(s): Andrea Klein , Sebastian Nemestothy , Julia Kadnar , Michael Grabner In the present study, 208 furniture and 168 coopered vessels from three Austrian museums were examined. Dendrochronology was used to date objects and to extract further information such as the necessary time for seasoning, wood loss through wood-working and methods of construction. In most cases sampling was done by sanding the cross section and making digital photographs using a picture frame and measuring digitally. The dendrochronological dates of the sampled furniture range between 1524 and 1937. The group of furniture includes cupboards, chests, tables, benches, commodes and beds. In many cases furniture was artfully painted and sometimes even shows a painted year. With the help of dendrochronology it was proved that some objects had been painted for some time after construction, or had been over-painted. Most furniture, however, was painted immediately after completion. In this case the seasoning and storage time of the boards and the wood loss due to shaping can be verified. As an average value, 14 years have passed between the dendrochronological date of the outermost ring and the painting. The time span includes time of seasoning and storage and the rings lost by wood-working. This leads, on the one hand to a short storage time of less than ten years and on the other hand to very little wood loss due to manufacturing. Those boards being less shaped turned out to be back panels of cupboards, therefore they are recommended to be sampled for dating. Coopered vessels were dated between 1612 - 1940. There was evidence that staves were split and not sawn in many cases. The staves were often split out of the outermost part of the tree and hardly any wood was worked away which was proved by the close dendrochronological dates of the single staves of a vessel. Since there is a short time of storage and only little wood loss through wood-working, dating of objects without a waney edge becomes reasonable.

Description: Publication date: Available online 11 October 2013 Source: Dendrochronologia Author(s): Johannes Edvardsson , Thomas W.D. Edwards , Hans Linderson , Dan Hammarlund Comparison between growth variability, based on ring-width (RW) analysis, and moisture-sensitive signals in tree-ring carbon and oxygen stable-isotope composition provides increased understanding of how climate and hydrology influenced bog pines (Pinus sylvestris L.) at two sites in southern Sweden during the mid- and late Holocene. Tree-ring sequences from two subfossil trees collected at raised bogs having different hydrology and catchment size were analysed to probe the stable-isotope signals associated with two bog-wide episodes of growth depression, one during the Holocene Thermal Maximum and the other during the Neoglacial Transition. The occurrence of lower whole-wood δ 13 C and cellulose δ 13 C and δ 18 O values immediately prior to the onset of growth depression in both trees, suggesting increased atmospheric relative humidity, is consistent with the notion that excessive effective moisture impeded tree growth. Correlation analysis indicates that the growth response lagged about three years behind the decline in δ 13 C and δ 18 O values in each tree, possibly reflecting relatively slow rise in the local water table in response to wetter climate.

Description: Publication date: Available online 4 October 2013 Source: Dendrochronologia Author(s): Holger Gärtner , Sandro Lucchinetti , Fritz Hans Schweingruber The variability of wood anatomical features in the rings of trees and shrubs is known to be dependent on multifaceted environmental parameters. The ability to determine anatomical variations over longer time periods as decades or centuries is a step forward in dendroecological and dendroclimatological research. In this regard micro sectioning is still one of the basic requirements but sectioning devices (microtomes) designed for wood anatomical purposes are rarely available. We present an affordable heavy duty, but light-weight microtome operated with removable blades. This portable device enables the production of large sections for dendroclimatological reconstructions as well as various types of common sections for wood anatomical studies.

Description: Publication date: Available online 11 October 2013 Source: Dendrochronologia Author(s): Yun Zhang , Igor Drobyshev , Lushuang Gao , Xiuhai Zhao , Yves Bergeron We used dendrochronological methods to study disturbance history of a mixed Korean pine ( Pinus koraiensis Siebold et Zuccarini) dominated forest on the northern slope of Changbai Mountain, North Eastern China, over 1770-2000. Frequent small-scale canopy gaps and infrequent medium-scale canopy disturbances dominated natural disturbance regime in the forest, which didn’t experience stand-replacing disturbances over the studied period. Percentages of growth releases in subcanopy trees were below 6% in most decades, suggesting that disturbances initiating these releases were of low intensity. Strong winds were likely cause of moderate disturbance events. Two episodes with increased disturbance rates (19% and 13%) were dated to the 1920s and 1980s, timing of the 1980s event was consistent with a hurricane occurred in 1986 on the western slope of the Changbai Mountain. Age structure and growth release analyses revealed species-specific regeneration strategies of canopy dominants. Shade-intolerant Olga bay larch ( Larix olgensis Henry) recruited mainly before the 1860s. Recruitment of moderately shade-tolerant P. koraiensis occurred as several regeneration waves (1820s, 1850s, 1870-1880s, 1930s, and 1990-2000s) of moderate intensity. Shade-tolerant Jezo spruce ( Picea jezoensis Carr. var. komarovii (V.Vassil.) Cheng et L.K.Fu) and Manchurian fir ( Abies nephrolepis (Trautv.) Maxim.) regenerated continuously over the last 220 and 130 years, respectively. Enhanced recruitment of P. koraiensis , P. jezoensis , and A. nephrolepis was observed during the 1930s and 1990s, coinciding with increased growth release frequency in the 1920s and 1980s, and suggesting disturbance events of moderate intensity. Our results indicate that the current disturbance regime of the mixed Korean pine dominated forest maintains coexistence of light-demanding and shade-tolerant species and that change in wind climate may be particularly important for future forest composition.

Description: Publication date: Available online 21 March 2014 Source: Dendrochronologia Author(s): Melissa Dick , Trevor J. Porter , Michael F.J. Pisaric , Ève Wertheimer , Peter deMontigny , Joelle T. Perreault , Kerry-Lynn Robillard The early settlement history of Canada's National Capital Region, including Ottawa (Ontario) and Gatineau (Québec), was shaped in large part by the towering eastern white pine ( Pinus strobus ) forests that once covered the Ottawa Valley and fuelled a lucrative lumber export industry spanning the 19 th and much of the 20 th century. Some of the first dwellings and farmsteads of this era are still standing and serve as reminders of this history. A crucial piece of information in the assessment of a structure's heritage value is its date of construction. Unfortunately, this information is not always known and is approximated based on construction styles and other sources of information. In this study, dendroarchaeology methods are applied to constrain the construction dates of six historic structures in the National Capital Region of 19 th century vintage. A multi-century (AD 1670-2009) eastern white pine ring-width chronology was developed for dating the study structures using cross sections from sunken logs recovered from the Ottawa River and cores from live trees from the Petawawa Research Forest. The tree-ring inferred construction dates for the six structures ranged from 1830 to 1878. For most structures, historical records about the property or first inhabitants were available to corroborate the results. The ring-width chronologies of the individual structures were well correlated with the regional chronology (r avg = 0.63, p ≤ 0.01), and this regional coherence clearly demonstrates the value of tree-rings for heritage structure assessments and reconstructing the settlement history of this region.

Description: Publication date: Available online 29 March 2014 Source: Dendrochronologia Author(s): Mark D. Spond , Saskia van de Gevel , Henri D. Grissino-Mayer We sampled Rocky Mountain junipers (RMJ) to produce a multi-century tree-ring chronology from a relict lava flow, the Paxton Springs Malpais (PAX), in the Zuni Mountains of western New Mexico. Our objective was to assess crossdating potential for RMJ growing on the volcanic badlands of the region, investigate potential relationships between climate and RMJ growth, and investigate temporal variability in relationships identified between climate and RMJ growing at our site. We hypothesized that, similar to other drought stressed-conifers growing on the lava flows, RMJ responds to climate factors that influence and indicate moisture availability. We found a high average mean sensitivity value (0.53), which indicated the PAX chronology exhibited enough annual variability to capture fluctuations in environmental conditions. The average interseries correlation (0.74) indicated confident crossdating and a significant association of annual growth among trees within the stand. The positive correlation between the PAX chronology and total precipitation for the local water year was significant (r = 0.53; P 〈 0.001). Significant positive correlations also were identified between monthly PDSI, monthly total precipitation, and RMJ radial growth. Analyses of temporal stability indicated that the positive relationship between RMJ growth at the PAX site and monthly PDSI was the most stable relationship during the period of analysis (1895–2007). More importantly, we identified a unique inverse relationship between radial growth and monthly mean temperature during periods of the preceding year and current growing year, the first such finding of a strong temperature response for a low-mid elevation tree species in the American Southwest. Our results confirm that RMJ samples collected on the Paxton Springs Malpais are sensitive to climate factors that affect moisture availability, further suggesting that RMJ may be suitable for use in dendroclimatic research at additional locations across the broad distribution of the species.

Description: Publication date: Available online 30 March 2014 Source: Dendrochronologia Author(s): Tongwen Zhang , Yujiang Yuan , Qing He , Wenshou Wei , Mamatkanov Diushen , Huaming Shang , Ruibo Zhang Three tree-ring width chronologies were developed from 75 Picea schrenkiana trees ranging from low- to high-elevation in the mountains surrounding the Issyk-Kul Lake, Northeast Kyrgyzstan. The reliable chronologies extend back to the mid-18th and late-19th centuries. Spatial correlation analysis indicates that the chronologies for the relatively high-elevation trees contain large-scale climatic signals, while the chronology at relatively low elevation may reflect the local climate variability. The results of the response of tree growth to climate show that these chronologies contain an annual precipitation signal. Furthermore, the influence of temperature indicates mainly moisture stress that is enhanced with rising elevation. The tree-ring records also captured a wetting trend in eastern Central Asia over the past decades. These new tree-ring width chronologies provide reliable proxies of precipitation variability in Central Asia and contribute to the International Tree-Ring Data Bank.

Description: Publication year: 2012 Source: Dendrochronologia Valery A. Tartakovsky, Victor I. Voronin, Anna N. Markelova A set of δ 18 O-tree-ring series obtained from larch trees growing in three different ecotopes near Lake Baikal are analysed together with the relevant meteorological data. It has recently been proposed that the external forcing factor, as a characteristic of the total investigated territory, must cause a certain similarity of the essential properties of the simple processes induced by this forcing. The similarity is the main point of this investigation and is the basis for a constructive definition of the intersection of the sets of these induced processes as data sets. We specify the elements of the intersection of the sets as the “common signals” for each process (set). The common signals are computed by a new algorithm of “co-filtering”, which is based on the trigonometric Fourier transform. We call the output of this algorithm the “co-filtered common signals” (CCS). We discovered that the CCS gave substantial contributions to the variances of the initial isotope series, which are more weakly correlated than their CCS. Next, we found that synchronous variations of the CCS of the temperature and precipitation for April–May and June–August induce synchronous variations in the CCS of the δ 18 O-tree-ring series. Furthermore, the characteristics of such synchronism vary with time. We concluded that the CCS of the δ 18 O-tree-ring series clearly express the external forcing factor even when there are significant differences in the vegetation conditions.

Description: Publication year: 2012 Source: Dendrochronologia A. Genries, I. Drobyshev, Y. Bergeron We used tree-ring data from a major North American boreal tree species, Jack pine ( Pinus banksiana Lamb.), to decipher spatial and temporal tree-growth responses to climate variability within the area of northwestern Quebec and northeastern Ontario. Fifteen sites with clay soils were selected and grouped into North and South sub-regions at approximately 49°N and 50°N, respectively. Tree-ring chronologies were analyzed through a response function for the years 1951–2000 to identify growth-limiting climate factors. Increased precipitation in June in the previous year and a warm month of April this year favored radial growth whereas higher temperature in September and increased precipitation in October, both of the previous year, and current June precipitation were negatively related to growth. There was a clear difference in climatic response between the southern and northern sub-regions: southern sites were more responsive to temperature dynamics while on northern sites Jack pine growth appeared negatively influenced by an excess of precipitation. Soil conditions, with larger areas covered by less water permeable clay deposits in the northern sub-region, explain this result.If recently observed trends towards warmer springs continue, Jack pine may increase its radial growth in the study area. However, increases in fall precipitation, also predicted under the future climate, may offset the positive effect of previous years weather on clay sites.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 23 February 2012 Kathryn Allen, David M. Drew, Geoffrey M. Downes, Robert Evans, Patrick Baker, ... The great majority of dendroclimatological work in Australia has thus far relied on ring-width chronologies only. We report novel results from a pilot study that show the potential to develop density-based climatically sensitive chronologies from two long-lived conifers endemic to Tasmania: Pencil Pine and Celery Top Pine. Cross-dating of average ring density profiles within each of the two sites examined was comparable with the better replicated ring-width chronologies from the sites. Cross-dating potential for maximum density was also indicated. Correlations between density and climate for both species were stronger and more persistent across a window of several months than correlations between ring width and climate. These stronger correlations suggest that temperature reconstructions based on average density may be possible. The ability to develop high resolution temperature-sensitive chronologies would allow for spatial comparisons across regions such as Tasmania that are affected by multiple broad-scale climate systems. A particularly novel result was the finding that maximum density was significantly related to stream-flow at the end of the growing season. Further work is required to assess the potential to reconstruct temperature, and to reconstruct stream-flow for important Tasmanian catchments over the past 500–800 years.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 17 February 2012 Samuli Helama, Margaret S. Devall

Description: Publication year: 2011 Source: Dendrochronologia, In Press, Corrected Proof, Available online 2 June 2011 Peter, Hietz I present a new software that links a program for image analysis (SigmaScan), one for spreadsheets (Excel) and one for statistical analysis (R) for applications of tree-ring analysis. The first macro measures ring width marked by the user on scanned images, stores raw and detrended data in Excel and calculates the distance to the pith and inter-series correlations. A second macro measures darkness along a defined path to identify latewood–earlywood transition in conifers, and a third shows the potential for automatic detection of boundaries. Written in Visual Basic for Applications, the code makes use of the advantages of existing programs...

Description: Publication year: 2011 Source: Dendrochronologia, Available online 16 September 2011 Julia Bartens, Henri D. Grissino-Mayer, Susan D. Day, P. Eric Wiseman Live oak (Quercus virginianaMill.) is a long lived, broadleaf, evergreen species native to the lower Coastal Plain of the southern and southeastern United States and is frequently planted in the urban environment. However, live oak has received limited attention for its potential for dendrochronological analyses possibly because its growth-ring boundaries may be less defined due to the absence of a distinct dormancy period. The objective of this explorative study was to determine whether live oak rings in both urban and historic trees could be accurately identified and measured for dendrochronological applications. One hundred urban live oaks were assessed as well as four cross-sectional specimens from historic sites in the southeastern United States. Age of all cored live oak ranged from 7 to 29 (average = 16.8 rings), while cross-sections were taken from trees with an average age of 175 years. A chronology was created from cores that had the highest interseries correlations (n = 27), resulting in an average interseries correlation of 0.654. The analysis of live oak cross sections revealed that the rings on live oak are very faint and barely discernible, delimited mainly by a faint row of earlywood vessels with no or barely visible terminal parenchyma. Rings on these sections were erratic (i.e., fading out along the circumference) and non-concentric (i.e., a particular ring could be both wide and narrow at certain points along the circumference) so that any attempt to measure the rings on opposing radii would have produced meaningless results. However, based on the results of this study, we conclude that the dendrochronological analysis of live oak is possible with careful sample preparation and analysis and that results would be reliable, even for urban trees. Results of this study suggest that urban tree-ring series with higher interseries correlations were more vigorous than those with lower values, suggesting that urban environmental stresses related to individual sites may decrease the usefulness of crossdating techniques for evaluating annual rings on younger, urban trees.

Description: Publication year: 2011 Source: Dendrochronologia, Available online 27 December 2011 Mariano M. Amoroso, María Laura Suarez, Lori D. Daniels This research examines the regeneration dynamics ofNothofagus dombeyiandAustrocedrus chilensisinA. chilensis-dominated forests growing near the eastern limit ofN. dombeyiwhere precipitation is limiting. In these forests the widespread decline and mortality of overstoryA. chilensistrees, known as ‘mal del ciprés’ (cypress sickness), generates large canopy gaps in which new individuals establish. Our objective was to study the population dynamics ofN. dombeyiandA. chilensisin these forests to investigate the influences of overstory tree death and climatic variation on establishment. We sampled 6 symptomaticA. chilensisstands and used dendrochronological techniques to reconstruct basal area development and regeneration establishment over time. Bivariate event analysis was performed to examine the temporal relationships between tree establishment and mortality events and climatic variation. OverstoryA. chilensistrees established as post-fire cohorts, with subsequent establishment ofA. chilensisandN. dombeyiduring the past 50–60 years. Regeneration in the past two decades was primarilyN. dombeyi.The establishment of bothA. chilensisandN. dombeyiwas synchronous with overstory tree mortality events, but it was more consistent among stands and prolonged forN. dombeyi. Establishment ofA. chilensiswas not associated with climatic events butN. dombeyiestablishment was synchronous with droughts, possibly related to climate-driven mortality creating canopy gaps or reducing competition within gaps. We have demonstrated thatN. dombeyihas the ability to establish in post-fireA. chilensis-dominated forests resulting in mixed-species, uneven-aged forests. The ongoing increase in the abundance ofN. dombeyirelative toA. chilensisrepresents a shift in composition and increased complexity in stand structure driven by ‘mal del ciprés’ and climatic variation.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 4 January 2012 Maxim Yermokhin This article presents for the first time Scots pine tree-ring chronology created from historical timber (XVII–XIX cc.) from central Belarus. The chronology includes 59 tree-ring series which were collected from the different wood structures in the Nesvizh castle. This samples show different stages of the castle renovations. The chronology presented in this paper embraces 222 years covering the period between 1608 and 1829.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 13 January 2012 Xiaohua Gou, Fen Zhang, Yang Deng, Gregory J. Ettl, Meixue Yang, ... Tree-line ecotones are strongly climatically limited and serve as potential monitors of climate change. We employed annual growth increment from tree-rings, and tree density and age structure data derived from twoJuniperus przewalskiitree-line sites in the eastern part of the Qilian Mountains, northeastern Tibetan Plateau, to detect the responses of tree growth and population dynamics to climate change. High temperature favors tree growth and is associated with increased tree density at tree-line, and an advance in tree-line position. Significantly positive correlations were found between ring-width and mean monthly air temperatures in current and previous June, July and August. Tree recruitment began to increase rapidly at the two sites after the Little Ice Age, but then decreased starting in the 1970s. The number of trees established coincides with temperature changes. The warming trend after the Little Ice Age favors increases of tree density and an advance of tree-line. The majority of trees established during the period of 1931–1970, which coincides well with the rapid radial growth of the trees.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 4 January 2012 Alar Läänelaid, Samuli Helama, Ain Kull, Mauri Timonen, Jaak Jaagus The common growth signal and spatial synchrony of nine chronologies of tree rings (Pinus sylvestrisL.) from the Baltic Sea region were studied using moving correlations with time windows of 50 and 100 years. Drifts from synchrony to asynchrony and again back to synchrony across several centuries were observed. The chronologies showed higher (or lower) coefficients of correlations and correspondingly gentler (or steeper) declines in spatial synchrony in certain periods. In accordance with research into other ecological phenomena, the origin of the spatial synchrony was found to relate to the intensity of the westerly circulation over the Atlantic and Europe as described by the North Atlantic Oscillation (NAO) index. The tree rings from all of the analysed subregions were found to be wider, identifying faster periods of growth, when there was a positive NAO during the extended winter season from December to March that preceded the period of growth. Previous studies showed that the NAO index can be linked with the growth of tree rings because of factors in the local climate that affect growth, such as temperature and precipitation. Moreover, the spatial synchrony showed multidecadal fluctuations that were correlated with variations of a similar scale in the reconstructed NAO index. However, a high degree of spatial synchrony was observed during the 20century in the presence of values of NAO index that were strongly negative. A more detailed view was provided by maps of the correlations in which spatial changes were demonstrated in the growth of pines between the 12and the 20century. These results could be used as background information in the development of improved proxy-based reconstructions of the NAO index (or other similar meteorological variables), which could also be inferred from tree ring data relating to earlier centuries.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 12 January 2012 Marc Macias-Fauria, Aslak Grinsted, Samuli Helama, Jari Holopainen Proxy data forms natural time series used to lengthen instrumental climatic records, and may contain a significant portion of autocorrelation. Increased serial correlation limits the number of independent observations, not satisfying the assumptions of conventional statistical methods. We estimate the significance of calibration and verification statistics used in dendroclimatic reconstructions by combining Monte-Carlo iterations with frequency (Ebisuzaki) or time (Burg) domain time series modelling. Significance tests are presented for Coefficient of Determination (R), Coefficient of Correlation (r), Reduction of Error (RE) and Coefficient of Error (CE) for time series ranging from very low to very high autocorrelation. Increased autocorrelation implies higher occurrences of relatively high but spurious reconstruction statistics. Ebisuzaki time series modelling shows greater robustness and its use is recommended over Burg's method, which penalizes the restriction in the number of autocorrelation coefficients imposed by the Akaike Information Criterion. Positive RE and CE values, traditionally viewed as successful reconstruction statistics, are not necessarily significant and depend on the temporal structure of the time series used. This approach is further implemented successfully to compute confidence intervals based on the temporal structure of the residuals of the transfer function. A Matlabpackage and a Windows executable file for non-Matlabusers are provided to perform the described analyses.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 13 January 2012 Pavel Pavlovich Silkin, Natalia Victorovna Ekimova This study addressed distribution of calcium and strontium in Siberian spruce (Picea obovataLedeb.) and Siberian fir (Abies sibiricaLedeb.) tree-rings and its dependence on these woody species cell structure. Calcium concentration was found to decrease gradually from earlywood to latewood, whereas strontium showed an opposite trend. However, their trends at the scale of several rings are co-directed in the samples analyzed. A strong linear relationship was identified between the distribution of Sr/Ca concentration ratio and tree-ring density profile for both woody species. Radiographic density of Siberian spruce tree-ring cell walls and Ca and Sr concentrations in them were determined to have negative correlation with cell wall thickness. In earlywood of annual rings of a spruce the radiographic density of cell wall reaches 2.0 g/cmand decreases to 1.2 g/cmin latewood. The hypothesis put forward in this study to explain these strontium and calcium distributions in the tree-rings is that the concentrations of the element ions change with development of different cell wall layers. The high value of radiographic density of a cellular wall in earlywood and its relationship with cell wall thickness can be explained by the presence of ions of calcium in a cellular wall. Ions of calcium absorb X-ray radiation more strongly in comparison with light chemical elements. It can become the reason of observable relationship between radiographic density of cell wall and cell wall thickness.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 25 January 2012 Igor Drobyshev, P. Charles Goebel, Yves Bergeron, R. Gregory Corace The study of forests dominated by red pine (Pinus resinosaAit.), one of the few fire-resistant tree species of eastern North America, provides an opportunity to reconstruct long-term fire histories and examine the temporal dynamics of climate forcing upon forest fire regimes. We used a 300-year long spatially explicit dendrochronological reconstruction of the fire regime for Seney National Wildlife Refuge (SNWR, 38,531 ha), eastern Upper Michigan to: (1) identify fire size thresholds with strong vs. weak climate controls, (2) evaluate effect of landform type (outwash channel vs. sand ridges) in modifying climate–fire associations, and (3) check for the presence of temporal changes in the climate control of large fire events over the time period 1700–1983. We used a summer drought sensitive red pine chronology (ITRDB codecan037) as a proxy of past fire-related climate variability. Results indicated that fires 〉60 ha in sand-ridge-dominated portions of SNWR and 〉100 ha in outwash channels were likely climatically driven events. Climate–fire associations varied over time with significant climate–fire linkages observed for the periods 1700–1800 (pre-EuroAmerican), 1800–1900 (EuroAmerican settlement) and 1900–1983 (modern era). Although an increase in fire activity at the turn of 20th century is commonly associated with human sources of ignitions, our results suggest that such an increase was also likely a climatically driven episode.

Description: Publication year: 2012 Source: Dendrochronologia, Available online 2 January 2012 Johannes Edvardsson, Hanns Hubert Leuschner, Hans Linderson, Hans W. Linderholm, Dan Hammarlund Dendroclimatic investigations of subfossil Scots pine (Pinus sylvestris) from two raised bogs in southern Sweden yielded a continuous floating 1492-year long tree-ring record. By cross-dating with bog-pine chronologies from Lower Saxony, Germany, the South Swedish record was assigned an absolute age of 5219–3728 BC. The cross-match between ring-width chronologies from these two regions, separated by 500–700 km, is remarkably strong and the correlation positive, which indicates that large-scale climate dynamics had a significant impact on the growth of bog pines during the Holocene Thermal Maximum (HTM) when bog-pine distribution reached a maximum in both regions. However, local population dynamics were also influenced by peatland ontogeny and competition, as shown by differences in replication and mean tree age between the Swedish and German records. Comparisons with chronologies developed from modern bog pines in southern Sweden indicate that more coherent climate was controlling pine growth on natural peatlands during warm periods in the past. This study demonstrates the usefulness of Swedish subfossil bog-pine material as a climate proxy, with particular potential for decadal- to centennial-scale reconstructions of humidity fluctuations.

Description: Publication date: Available online 2 October 2014 Source: Dendrochronologia Author(s): Katarina Čufar , Matjaž Bizjak , Manja Kitek Kuzman , Maks Merela , Michael Grabner , Robert Brus Castle Pišece, located in SE Slovenia near the border with Croatia, is thought to have been built in the 12 th /13 th century as one in the line of Salzburg fortresses on the then SE border of the Holy Roman Empire. During thorough restoration that started in 2005, its wooden constructions became accessible for dendrochronological investigations. We collected representative samples from floor or ceiling constructions in most of the rooms in the castle. Dendrochronology helped us to identify felling dates of wood and to propose probable years of reconstructions in 1515, 1578, 1644, 1697, 1752, 1758, 1775 and 1878. The dating showed that the constructions in the presumed Romanesque and Renaissance parts of the building were not as old as expected, whereas those in the supposedly Baroque part of the castle were older than assumed. The selection of wood species used for constructions varied over time. Constructions with end dates 1515-1697 were made of oak ( Quercus petraea and Q. robur ), those dated to 1752 of silver fir ( Abies alba ), those dated to 1758 of sweet chestnut ( Castanea sativa ) and those dated to 1878 of common beech ( Fagus sylvatica ). Comparison of forestry archives and vegetation in the area showed that most of the timber could have originated from nearby forests; only silver fir had to be transported from sites that were at least 20 km away from the castle. Cross-dating of tree-ring series of oak elements with two reference chronologies from Slovenia and two from Austria confirmed the great likelihood that the wood used mostly originated from Slovenia. This indicates that dendroprovenancing, not used in the area before, could also be used SE of the Alps. Both the existing archival documents and dendrochronology indicate that woodworks have taken place every few decades in some periods. The dendrochronological dates can be partly linked to reports on earthquakes (especially the devastating one in 1511), rebellions and year marks carved on the stone plaques. Graphical abstract

Description: Publication date: Available online 1 September 2014 Source: Dendrochronologia Author(s): Martin Hroš , Hanuš Vavrčík The differences in the microscopic structure of wood based on the variables of earlywood vessel area and tree ring width were analysed in 6 trees of Pedunculate oak (Quercus robur L.) and 6 trees of Sessile oak (Quercus petraea (Mattuschka) Liebl.) in the same forest stand at a site in the Vizovice Highland (Czech Republic). The aim of this paper was to assess any differences between the two oak species when grown in the same location. Also the effect of tree-ring width and the effect of age on earlywood vessel variables were analysed. Mean values of tree-ring widths were not different between species. Earlywood vessel area chronologies were synchronised well between species. The mean values of earlywood vessel area (average vessel area, average vessel area of the first row of vessels, area of the largest vessel) showed a significant difference. Finally, we can conclude that there were differences in vessel features between these oak species.

Description: Publication date: Available online 21 November 2014 Source: Dendrochronologia Author(s): Pearce Paul Creasman , Christopher Baisan , Christopher Guiterman More than 200 ships were built, and thousands serviced, at Charlestown Navy Yard (Boston, MA) in its 174 years of service for the U.S. Navy (1800–1974 C.E.). Recent redevelopment of portions of the former yard revealed an historic timber pond where hundreds of unfinished naval-quality ship timbers were intentionally sunk and remained buried until ca. 2008. Many of these timbers were offered to the Henry B. du Pont Preservation Shipyard (Mystic Seaport, CT) for their restoration of Charles W. Morgan . Courtesy of Mystic Seaport, thirty-eight specimens from the Charlestown yard (mostly Quercus sp.; including live [evergreen] oak and white oak) were selected for dendrochronological analysis. Most of the white oak specimens could be sourced with confidence to Ohio. Dates clustered in the late 1860's, suggesting late-Civil War or Reconstruction Era activities. This paper discusses the dates, origin, and other findings derived from this collection.