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Gases desorbed by the vacuum method from the tree rings of discs of deciduous trees are measured. The content of residual gases vacuum-desorbed from tree rings is analyzed with an optoacoustic gas analyzer with a tunable CO2 laser. The chronologies of residual CO2 and (CO2 + H2O) of some deciduous trees growing near the city of Tomsk (Western Siberia) have been derived. All the chronologies are cyclic with pronounced 2–4-year cycles. A correlation was found between the content of gases and summer temperatures and precipitation. We believe that the annual distribution of residual gases in the discs reflects the pattern of annual release of the gases from the stems of the deciduous trees into the atmosphere. [ABSTRACT FROM AUTHOR]

The aim of this study was a comparative retrospective assessment of radiocarbon (14C) as a tracer, caused by operational emissions of Rivne and Chornobyl nuclear power plants (NPPs), which are equipped with different types of nuclear reactors. For this purpose, 14C was studied in annual tree rings of pine taken at a distance of 1.5 km southwest of the Rivne NPP and at a distance of 3.5 km west-northwest of the Chornobyl NPP, near the Yaniv railway station. As a background, we use the 14C in air data (Hua et al. 2013), which we continue for time interval 2009–2020 with our experimental data for pine tree rings. Tree rings were also collected in a rural area 60 km west of Kyiv, where industrial impact, in our opinion, is absent. 14C in wood samples was determined using the conventional method based on liquid scintillation counting. It was found that the 14C excess in the annual tree-ring samples of pine near the Chornobyl NPP during the observed operation period (1984–2000) was 3.0–13.0 pMC, except for the 1986, the year of the Chornobyl accident, when the 14C value rose sharply to 182.7 pMC (14C excess 62 pMC). After 2000, the content of 14C in the air near the Chornobyl nuclear power plant did not exceed the background values within the uncertainty of the measured data. The concentration of 14C in the samples of annual tree rings of pine near the Rivne NPP for the observation period (1986–2019) corresponded to the background levels within the uncertainty of the measured data. The study of environmental traces of 14C emissions from two NPPs equipped with different types of reactors showed significantly lower emissions of Rivne NPP with VVER compared with emissions from Chornobyl NPP with RBMK reactors. [ABSTRACT FROM AUTHOR]

This mini-review is devoted to dendrogenomics, a new interdisciplinary field of research that integrates dendrochronology, dendroecology, dendroclimatology, genetics and genomics. This novel approach allows joint analyses of dendrological and genomic data and opens new ways to study temporal dynamics of forest treelines, to delineate spatial and temporal population structure and, most of all, to study the adaptive genetic potential of forest tree populations. These problems are especially relevant to predicting how climate change will shape distribution of boreal forest species. [ABSTRACT FROM AUTHOR]

The main goal of this study was to evaluate the patterns of diametric increment of open-grown and under competition trees of Pinus taeda L. as an expression of breast height diameter. The dendrometric variables and the diameter increment of these trees were measured. The increments were obtained by measuring tree rings on cores extracted at breast height using a Pressler borer. An allometric model was fitted to describe the percentage periodic annual increment in diameter (PAId%) as a function of the initial diameter (di) for two tree groups. The analysis of covariance (ANCOVA) allowed comparing the effect of intercept (α0) and slope (α1) of the fitted equations between groups. The overall average of PAId5 was 0.83 cm year-1 for open-grown trees and 0.57 cm year-1 for under competition trees. The ANCOVA showed differences in intercept (α0) - (Pr > F = 0.0066) and not in slope (α1) - (Pr > F = 0.8883) for the adjusted regression equations. This finding enabled the development of a singular equation to express the increment, using dummy variables, described as: PAId% = exp [...], with R² = .69 and Syx = 2.4%. The results of this study contribute to highlight the influences of the growth space in the increment of the species, as well as its maximum potential, elements that are very important for the monitoring and decision-making process in silvicultural activities of individual P. taeda trees. [ABSTRACT FROM AUTHOR]

The radiocarbon (14C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties. [ABSTRACT FROM AUTHOR]

Drought-triggered declines in forest productivity and associated die-off events have increased considerably due to climate warming in the last decades. There is an increasing interest in quantifying the resilience capacity of forests against climate warming and drought to uncover how different stands and tree species will resist and recover after more frequent and intense droughts. Trees form annual growth rings that represent an accurate record of how forest growth responded to past droughts. Here we use dendrochronology to quantify the radial growth of different forests subjected to contrasting climatic conditions in Spain during the last half century. Particularly, we considered four climatically contrasting areas where dominant forests showed clear signs of drought-induced dieback. Studied forests included wet sites dominated by silver fir (Abies alba) in the Pyrenees and beech (Fagus sylvatica) stands in northern Spain, and drought-prone sites dominated by Scots pine (Pinus sylvestris) in eastern Spain and black pine (Pinus nigra) in the semi-arid south-eastern Spain. We quantified the growth reduction caused by different droughts and assessed the short-and long-term resilience capacity of declining vs. non-declining trees in each forest. In all cases, drought induced a marked growth reduction regardless tree vigor. However, the capacity to recover after drought (resilience) at short- and long-term scales varied greatly between declining and non-declining individuals. In the case of beech and silver fir, non-declining individuals presented greater growth rates and capacity to recover after drought than declining individuals. For Scots pine, the resilience to drought was found to be lower in recent years regardless the tree vigor, but the growth reduction caused by successive droughts was more pronounced in declining than in non-declining individuals. In the black pine forest an extreme drought induced a marked growth reduction in declining individuals when accounting for age effects on growth rates. We demonstrate the potential of tree-ring data to record short- and long-term impacts of drought on forest growth and to quantify the resilience capacity of trees.

Every so often, the results obtained from investigations into the effects of varying environmental conditions on the tree growth rate at the same sites and on the change in the carbon balance in plants, using traditional methods, are found to differ widely. We believe that the reason for the ambiguity of the data has to do with failure to account for the role of the residual CO2 (and H2O) in the tree wood exhibiting a climate response. In our earlier work, the results of a laser photoacoustic gas analysis of CO2 and H2O vacuum-desorbed from disc tree rings of evergreen conifer trees were presented. In this paper, laser photoacoustic measurements of tree ring gases in deciduous conifer trees and CO2 carbon isotope composition determined by means of a mass spectrometer are given. Conclusions are made regarding the response of annual larch CO2 disc tree ring distributions to climatic parameters (temperatures and precipitation). The data about the CO2 disc content for different sites are compared.

Drought-induced growth decline is a phenomenon widely described in forests growing in regions subjected to seasonal water shortage such as the Mediterranean Basin. However, how tree species react to drought by modifying their growth pattern across the species distribution range is a question that remains to be answered. We investigate this question using a network of 27 Aleppo pine forests distributed across the eastern Spain and encompassing diverse site characteristics and climatic conditions. Using dendrochronology we quantify the radial growth responses of this Mediterranean tree species in 1994–1995, when the most severe drought after 1950 affected the study area. We quantify the variation between trees and sites in terms of growth resilience to drought, i.e. the resistance to the drought event and the recovery after it. Then, we quantify the relationship of these responses to tree traits (tree diameter and height, tree age, sapwood area) at the individual tree level, and to site characteristics (climate conditions, stand structure–tree density, basal area and the presence of co-dominant tree species) at the site level. We found that 1994–95 dry spell strongly impacted tree growth since 25 out of 27 sites and about 88% of trees showed a marked growth reduction of around 60% in radial growth. Climatic conditions were by far more important than tree traits on explaining resilience indices. In particular, the resistance to drought decreased with the increase in drought intensity, whereas the post-drought recovery was linked to site precipitation. Trees from dry sites were less resistant but recovered faster than trees from wet sites. We demonstrate that the reaction of different tree populations to drought is structured according to local climate conditions. If droughts become more severe and frequent as predicted in the Mediterranean region where climate warming is forecasted, Aleppo pine stands growing in the driest regions will be increasingly more sensitive to intense dry spells. [ABSTRACT FROM AUTHOR]

Aprovechando la formación de anillos anuales de crecimiento en los hospedadores y que el sistema haustorial de los muérdagos va quedando sincrónicamente embebido en el xilema del hospedador, analizamos características edad dependientes de la historia de vida y del establecimiento de Misodendrum punctulatum cuando infecta a dos especies deciduas de Nothofagus en el noroeste de la Patagonia, Argentina. La determinación de la edad de establecimiento de las infecciones fue realizada examinando el número de anillos anuales de crecimiento del hospedador, en cortes transversales de ramas o troncos principales de Nothofagus, atravesados por el haustorio más profundo. Concomitantemente, se registró el número de eventos anuales de crecimiento (índice de edad aérea) y el diámetro basal de los tallos de los muérdagos. Los anillos de crecimiento de los hospedadores precedentes al establecimiento de los muérdagos fueron usados para determinar la edad las ramas o troncos principales al ser infectados. La relación entre la edad haustorial y el índice de edad aérea indican que: (1) el recuento de los eventos de crecimiento de los tallos es un método no destructivo adecuado para estimar la edad de este muérdago mientras que el diámetro basal es un método menos eficiente, (2) al inicio del desarrollo M. punctulatum presenta un período de incubación holotrófico, de varios años, antes de producir estructuras aéreas, (3) la duración del período de incubación es sitio y/u hospedador dependiente siendo más extenso (4 a 6 años) en bosques subalpinos de Nothofagus pumilio y más corto (2 años) en matorrales de N. antarctica en bajas altitudes ,(4) cuando los muérdagos viven en bosques subalpinos de Nothofagus pumilio en sitios desfavorables crecen más lento y son más longevos que cuando están en matorrales de N. antarctica en bajas altitudes. Misodendrum punctulatum infecta principalmente ramas jóvenes (< 4 años) sugiriendo una fuerte limitación mecánica del haustorio para penetrar cortezas de mayor espesor. Cuando se observaron infecciones de M. punctulatum en los troncos principales de Nothofagus y se analizaron, la edad total del sistema haustorial no reveló infecciones vegetativas (invasión sistémica) durante la etapa juvenil de los hospedadores. Múltiples y discretos eventos de renovación del sistema endofítico, con una duración de aproximadamente 24 años cada uno, posiblemente estén relacionados con el mantenimiento de una conexión apropiada con el xilema funcional del hospedadorTaking advantage of host annual ring formation and synchronic embedding of the mistletoe haustorial system within the host xylem, we analyzed age-dependent life history traits and establishment conditions of Misodendrum punctulatum (Misodendraceae) infecting two deciduous species of Nothofagus in northern Patagonia, Argentina. Absolute determination of infection ages was performed by examining the number of host tree rings traversed by deepest haustoria in slices/cross-sections of parasitized branches/main trunks. Concomitantly, the number of branching events and basal stem diameters were taken from emerging aerial parts of the mistletoes. Host rings preceding the infection were used to determine branch trunk ages-1 during infection. Relationships between haustorial and aerial age indices indicate that: (1) branching events are good non-destructive estimators of mistletoe age while basal diameters were poor estimators of age, (2) early development of M. punctulatum includes a multiyear holotrophic incubation period before producing aerial shoots, (3) the incubation period span is site and/or specie dependent being longer (4-6 yr) on the subalpine Nothofagus pumilio, and shorter (2 yr) on the lower altitude shrub N. Antarctica, (4) Mistletoes infecting subalpine trees of Nothofagus pumilio in the harsher sites grew slower and were longer-lived than mistletoes infecting lower altitude shrubs of N. antarctica. M. punctulatum infected only young host branches (< 4 yr) suggesting strong limitations of mechanically penetrating thicker bark. When M. punctulatum shoots were present on Nothofagus trunks, absolute aging of haustorial systems in cross-sections revealed non-vegetative infections when trees were saplings. Multiple discrete events of renewal of the endophytic system spanning each about 24 yr are probably related to the maintenance of appropriate connections with functional host xylem

Every so often, the results obtained from investigations into the effects of varying environmental conditions on the tree growth rate at the same sites and on the change in the carbon balance in plants, using traditional methods, are found to differ widely. We believe that the reason for the ambiguity of the data has to do with failure to account for the role of the residual CO2 (and H2O) in the tree wood exhibiting a climate response. In our earlier work, the results of a laser photoacoustic gas analysis of CO2 and H2O vacuum-desorbed from disc tree rings of evergreen conifer trees were presented. In this paper, laser photoacoustic measurements of tree ring gases in deciduous conifer trees and CO2 carbon isotope composition determined by means of a mass spectrometer are given. Conclusions are made regarding the response of annual larch CO2 disc tree ring distributions to climatic parameters (temperatures and precipitation). The data about the CO2 disc content for different sites are compared. [ABSTRACT FROM AUTHOR]

Despite the progress made during the past 20 years, searching dendrochronological potential in tropical and subtropical tree species, tropical dendrochronology, is still in a development stage. The aim of this research was to determine the potential of C. odorata for dendrochronological studies in the Selva Central of Perú. The tree-ring anatomical characteristics were carefully examined and we were able to develop a 215 year (1 795-2 009) tree-ring chronology and correlate it with precipitation records. The tree-ring chronology was developed based on 47 series of 27 trees. Tree rings are clearly delimited by large pore diameters in earlywood and small ones in latewood associated with marginal and paratracheal parenchyma. The tree-ring chronology was related to precipitation records from Satipo and significant correlations were found with the previous rainy season and late dry season of the current growth period. Moreover, we found close relationship between tree growth and total precipitations of the hydrological period (December to September) for the interval 1 990-2 009. These results demonstrate the influence of rainfall at different stages of C. odorata radial growth. The good discrimination of annual rings, strong relationship with precipitation, the wide range and longevity of trees (200 years) make C. odorata a very promising species for dendrochronological studies in tropical and subtropical forest of America. [ABSTRACT FROM AUTHOR]

The properties of El Niño-Southern Oscillation (ENSO), such as period, amplitude, and teleconnection strength to extratropical regions, have changed since the mid-1970s. ENSO affects the regional climatic regime in SW Europe, thus tree performance in the Iberian Peninsula could be affected by recent ENSO dynamics. We established four Quercus robur chronologies of earlywood and latewood widths in the NW Iberian Peninsula. The relationship between tree growth and the Southern Oscillation Index (SOI), the atmospheric expression of ENSO, showed that only latewood growth was correlated negatively with the SOI of the previous summer-autumn-winter. This relationship was non-stationary, with significant correlations only during the period 1952-1980; and also non-linear, with enhanced latewood growth only in La Niña years, i.e. years with a negative SOI index for the previous autumn. Non-linear relationship between latewood and SOI indicates an asymmetric influence of ENSO on tree performance, biassed towards negative SOI phases. During La Niña years, climate in the study area was warmer and wetter than during positive years, but only for 1952-1980. Winter temperatures became the most limiting factor for latewood growth since 1980, when mean regional temperatures increased by 1°C in comparison to previous periods. As a result, higher winter respiration rates, and the extension of the growing season, would probably cause an additional consumption of stored carbohydrates. The influence of ENSO and winter temperatures proved to be of great importance for tree growth, even at lower altitudes and under mild Atlantic climate in the NW Iberian Peninsula. [ABSTRACT FROM AUTHOR]

Land use change and climate change have been increasingly contributing to loss or reduction of biological and economic productivity of arid lands. The dry climate and physiographic characteristics of the Peninsula of La Guajira on the Colombian Caribbean coast are considered to be crucial drivers of the loss of vegetative cover and soil erosion; however, little knowledge exists on long-term changes in climate in the area. This study presents a tree-ring chronology from Parkinsonia praecox (18 trees, 45 radii) that allows the reconstruction of local and global climate drivers spanning the last 63 years. Tree-ring width was strongly correlated with rainfall and wind data, indicating that annual tree growth was closely related to local climatic variability. The chronology also strongly correlated with an index of ENSO severity (El Niño Southern Oscillation), suggesting that large-scale climatic phenomenon also have important influence on Parkinsonia growth. To further investigate rainfall-growth relationships, climate data series of annual rainfall and rainfall from September to November (SON), the rainiest months, were reconstructed using transfer functions. These data series did not exhibit a clear trend of change in rainfall over the last 63 years. The transfer functions reconstructed the total annual rainfall ( R2 = 0.8), and SON ( R2 = 0.7). This study constitutes the first attempt to reconstruct climatic patterns in Colombia with techniques of dendrochronology, and demonstrates the potential of Parkinsonia praecox for studying climatic patterns along the American subtropics, ranging from Mexico to Argentina. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Abstract: Tree ring scientists have generally ignored the use of dendrochronological techniques to assess growth impacts of cultural treatments for the major horticultural trees in plantations. In this study, we investigated differences in radial growth between orange (Citrus) trees, a non-native subtropical species, growing in plantations in northern Costa Rica and southern Nicaragua that were either treated or untreated with the fungicide Benlate 50 DF (benomyl), which has potential phytotoxic effects. This region of Central America experiences prolonged and severe drought from January through April each year, during which an average of only 10% (about 260mm) of the annual rainfall occurs. Basal cross-sections taken from the citrus trees reveal distinct annual tree rings that closely match the ages of the trees. The rings are reasonable concentric and have good circuit uniformity. An analysis of 111 tree cores indicates that Benlate 50 DF treated trees had significantly slower radial growth during their first 6 years (averaging 4.54mm/year) than untreated trees (averaging 10.76–11.84mm/year). After year 6, the treated trees had a similar growth rate (11.27mm/year) to the untreated trees. Four cores taken from each of 10 citrus trees at cardinal directions around the stem reveal that the mean growth rate from any one aspect did not differ significantly from the mean growth per tree. Further analysis of these cores indicates that taking one or two random cores per tree produced a similar average growth calculation. The results of this study suggest that young citrus trees produce distinct annual tree rings in a seasonally dry tropical environment, that trees treated with Benlate 50 DF had slower radial growth during their first 6 years, and that, with proper replication, taking one core per tree was adequate to assess radial growth. But this latter point needs to be determined by researchers on a case-by-case and species-by-species basis. The approach used in this study to determine growth impacts following chemical application may have widespread application for other agricultural practices in a variety of horticultural woody plants worldwide. [Copyright &y& Elsevier]

There is a limited knowledge about the El Niño–Southern Oscillation (ENSO) effects on the Amazon basin, the world's largest tropical rain forest and a major factor in the global carbon cycle. Seasonal precipitation in the Andean watershed annually causes a several month-long inundation of the floodplains along the Amazon River that induces the formation of annual rings in trees of the flooded forests. Radial growth of trees is mainly restricted to the nonflooded period and thus the ring width corresponds to its duration. This allows the construction of a tree-ring chronology of the long-living hardwood species Piranhea trifoliata Baill. (Euphorbiaceae). El Niño causes anomalously low precipitation in the catchment that results in a significantly lower water discharge of the Amazon River and consequently in an extension of the vegetation period. In those years tree rings are significantly wider. Thus the tree-ring record can be considered as a robust indicator reflecting the mean climate conditions of the whole Western Amazon basin. We present a more than 200-year long chronology, which is the first ENSO-sensitive dendroclimatic proxy of the Amazon basin and permits the dating of preinstrumental El Niño events. Time series analyses of our data indicate that during the last two centuries the severity of El Niño increased significantly. [ABSTRACT FROM AUTHOR]