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Dendrochronological and dendroclimatic analyses of radial growth of trees in shelterbelts of the dry-steppe subzone are presented. In dry steppe conditions, trees of shelterbelts are very sensitive to climate change and are forced to adapt to extreme conditions, which directly affects their annual increment. The radial growth of trees and their response to climatic factors are determined by their species composition and geographical location within the dry steppe. The rates of radial growth vary significantly among species. Poplars show the highest increment. Larch chronologies are characterized by the lowest rates of radial growth. Birch chronologies are the most sensitive to climatic fluctuations, and pine chronologies are the least sensitive. A statistically significant relationship with precipitation, temperature, area moisture index (with the Selyaninov hydrothermal coefficient), and the Palmer Drought Severity Index (sc-PDSI) is noted. A deficiency of precipitation and increased air temperature most often cause a decrease in the wood increment. A large number of narrow, wedging, and missing reference rings were noted. The analysis of the age structure of the studied trees of shelterbelts showed that they are moving into the senile stage of development. Further increase in climate aridization will inevitably affect the growth of trees of shelterbelts and create additional risks for their existence. [ABSTRACT FROM AUTHOR]

Tree-ring chronologies based on the annual ring width of Scots pine (Pinus sylvestris L.) have been studied at eight test sites in insular pine forests in the north of the Republic of Kazakhstan from the Turgay Depression to the eastern part of the Kazakh Uplands. Analysis of the relationships between radial increment of pine and climate shows that the climatic signal in the chronologies can change depending on geomorphological conditions caused by the edaphic factor, relief, and absolute elevation marks. These features must be taken into account when using tree-ring chronologies for spatiotemporal reconstructions of climate. [ABSTRACT FROM AUTHOR]

It has been studied that the climatic conditions of the Right-bank Forest-Steppe of Ukraine, in particular the amount of precipitation and average monthly temperatures, affect the growth and development of walnut, a characteristic species of this region. The importance of studying the influence of climatic factors on the growth of forest plantations was noted, and the need to take into account these factors when growing walnuts in the climatic conditions of the Right-Bank Forest Steppe, characterized by a high level of precipitation in the first half of the growing season, was emphasized. This factor plays an essential role in ensuring a favorable soil moisture regime. In the second half of the growing season (July-August), on the contrary, a decrease in precipitation was observed, which has an ambiguous effect on the productive reserves of moisture in the soil. In particular, it was found that in May, only during a short period of the years studied (1995-2001), the level of precipitation was optimal - 40-50 mm, over the course of four years (2003, 2004, 2009 and 2013), it decreased slightly – 30- 40 mm. The statistical analysis of annual increments shows their suitability for further analysis since these series have an inter-series correlation coefficient of 0.59 for the plantation forest and 0.55 for the natural forest stand. The sensitivity of the tree-ring chronology of the plantation forest slightly exceeds the average value and is 0.32, while for the natural forest stand on the contrary, it is 0.17 and is lower than the average value. Thus, walnuts under plantation cultivation are more sensitive to variations in environmental conditions compared to natural forest stands. Based on the analysis of the values of radial increment, standard deviation, coefficients of variation, and sensitivity, the walnut growth and development periods are distinguished, characterized by certain features and conditions for plant growth. Based on the value of the sensitivity coefficient, it was found that walnut stands growing in natural forest conditions are more steady-state. It was found that the radial increment of walnuts under plantation cultivation showed a significant negative relationship with precipitation. Conversely, precipitation did not significantly affect the formation of diameter growth in trees growing in natural forest conditions. The correlation analysis for two periods of plant growth (the first period 1994-2003 and the second period 2004-2023) showed that due to climate changes, namely, an increase in air temperature and a decrease in the amount of precipitation (which was irregular and intense) changed growth response both in forest ecosystems and plantations. In the growing season of 2004-2023, with an increase in the intensity and frequency of extreme weather conditions during the vegetative development of plants, such as high air temperatures and moisture deficit, the negative impact of these phenomena on the growth of walnuts was observed. The different response of walnuts grown in plantation and natural forest conditions to climatic changes makes it possible to apply technological measures to mitigate or reduce the manifestation of negative stressful climatic effects.

Abstract: Atmospheric rivers (AR) are critically important to water resources management along the US west coast, driving variability in both droughts and floods across the region. Inter‐annual variability of ARs is well documented in the instrumental record back to the mid‐twentieth century, but long‐term variations in the frequency and landfall location of ARs along the US west coast are poorly understood due to limited records. This limitation impedes the ability to contextualize emerging trends and projections of AR activity. Here we use station‐based records of daily precipitation and tree‐ring records to present novel, spatially explicit estimates of daily AR occurrences in the first half of the twentieth century and annual AR counts over the last 600 years. First, we use neural networks and daily precipitation across Western North America to classify the daily occurrence of AR landfalls in three regions along the US west coast during the cold season back to 1916 CE. Then, we reconstruct the annual frequency of AR landfalls in those same regions back to 1400 CE using a gridded, tree‐ring based reconstruction of the standardized precipitation index and a Poisson regression framework. The skillful reconstruction of daily and annual AR occurrences provides previously unavailable estimates of AR landfall variability and highlights new peaks in AR activity and modes of low‐frequency variability prior to the instrumental record. Our reconstructions suggest that the average latitude of AR landfall has varied considerably on multi‐decadal scales over the last 600 years, but without any discernible trends beyond this quasi‐oscillatory behavior.

The frequency, intensity, and duration of extreme droughts, with devastating impacts on tree growth and survival, have increased with climate change over the past decades. Assessing growth resistance and resilience to drought is a crucial prerequisite for understanding the responses of forest functioning to drought events. However, the responses of growth resistance and resilience to extreme droughts with different durations across different climatic zones remain unclear. Here, we investigated the spatiotemporal patterns in growth resistance and resilience in response to extreme droughts with different durations during 1901–2015, relying on tree‐ring chronologies from 2389 forest stands over the mid‐ and high‐latitudinal Northern Hemisphere, species‐specific plant functional traits, and diverse climatic factors. The findings revealed that growth resistance and resilience under 1‐year droughts were higher in humid regions than in arid regions. Significant higher growth resistance was observed under 2‐year droughts than under 1‐year droughts in both arid and humid regions, while growth resilience did not show a significant difference. Temporally, tree growth became less resistant and resilient to 1‐year droughts in 1980–2015 than in 1901–1979 in both arid and humid regions. As drought duration lengthened, the predominant impacts of climatic factors on growth resistance and resilience weakened and instead foliar economic traits, plant hydraulic traits, and soil properties became much more important in both climatic regions; in addition, such trends were also observed temporally. Finally, we found that most of the Earth system models (ESMs) used in this study overestimated growth resistance and underestimated growth resilience under both 1‐year and 2‐year droughts. A comprehensive ecophysiological understanding of tree growth responses to longer and intensified drought events is urgently needed, and a specific emphasis should be placed on improving the performance of ESMs. [ABSTRACT FROM AUTHOR]

ABSTRACTAccurate reconstructed series are crucial for studying the differences in regional hydroclimatic variations in Europe over the past millennium. Using hierarchical clustering analysis and stepwise regression methods, we reconstructed yearly time series of the summer standardized precipitation evapotranspiration index (SPEI) for six European regions over the past millennium. Our analysis also revealed prominent regional hydroclimatic differences in multidecadal signals over the past 500 years. For instance, in the 1500s–1570s (from the beginning of the 1500s to the end of the 1570s), drying trends were observed in northern and southeastern Europe, whereas southwestern Europe experienced a wetting trend. Moreover, drying trends were observed in northern and central Europe in the 1640s–1670s. Additionally, wetting trends were observed in western and central Europe during the 1830s–1850s, with drying trends in northern and southeastern Europe. Notably, the hydroclimatic variations in most European regions showed drying trends in the 1920s–1950s, especially in southern Europe. By utilizing large amounts of tree-ring samples and directly comparing regional hydroclimatic variations, our reconstructions provide a consistent and comprehensive dataset for further analysis. The reconstructed dataset is available at https://doi.org/10.57760/sciencedb.07215.

A dendrochronological network of conifers (Pinus leiophylla, Pinus cembroides, Pinus engelmannii) was developed in the Cumbres de Majalca National Park (CMNP) in Chihuahua, Mexico, to reconstruct historical runoff patterns and examine the impact of ocean–atmosphere phenomena. The CMNP plays a vital role as a runoff source for Conchos River tributaries and groundwater recharge for Chihuahua City and nearby populations. The ring-width chronologies displayed a common signal from 1859 to 2021, with the highest association found between P. engelmannii and P. leiophylla (r = 0.65) and the lowest between P. cembroides and P. engelmannii (r = 0.55). The first principal component explained 75.7% of the variance, and among the species, P. leiophylla exhibited the highest correlation (0.624, p < 0.05) with the accumulated streamflow records from the previous November to July, allowing the construction of a bootstrapped model for runoff reconstruction. The reconstructed streamflow spanned from 1859 to 2014, with an average of 2.732 × 108 m3. Periods of low runoff occurred in 1860–1880, 1940–1960, and 1994–2014, while extreme wet years with high runoff occurred in 1865, 1884, and 1987. The interannual streamflow variability correlated significantly with ENSO indices (SOI, MEI, TRI, and sea surface temperature anomalies), particularly during the winter–spring seasons, indicating that warm phases of the ENSO increased precipitation and runoff. The analysis of return periods revealed probabilities for specific runoff volumes, enabling stakeholders to use the information to develop effective strategies for sustainable water allocation and utilization in the region. [ABSTRACT FROM AUTHOR]

Extreme weather variability has long posed difficulties for food, energy, and water systems in the Western US and is only projected to become more variable in a changing climate. The key to understanding weather in the West lies in understanding variability of large-scale weather regimes that dictate regional weather patterns. In this study, we propose a novel, multi-objective optimization and regression-based framework that reconstructs the annual frequency of regional weather regimes based on a gridded, tree-ring based reconstruction of cold season precipitation. The approach optimally smooths and selects the tree-ring based information used in the weather regime reconstruction to enhance out of sample performance and minimize model complexity. Multiple objectives are considered within the optimization to balance the preservation of low and high frequency modes of variability in the multivariate weather regime dynamics. We reconstruct weather regime frequencies back to 1400 CE and show that the reconstructed weather regimes are consistent with previously identified megadroughts and pluvials. Further, the reconstructed weather regimes exhibit significant variability in the 3–15-year frequency band and extend far beyond the bounds of the instrumental period. Overall, the weather regime reconstructions developed here provide important insight into the extent of natural atmospheric variability that can influence Western US weather. [ABSTRACT FROM AUTHOR]

Prof. Dr. Dieter Eckstein (1939-2021) was a leading scientist, teacher, mentor, leader, promoter and motivator in the field of dendrochronology and wood biology. After graduating in wood science and receiving a PhD in dendrochronology, he was professor of wood biology at the University of Hamburg. From 1995-2004, he was Director of the Department of Wood Biology, University of Hamburg, and of the Institute of Wood Biology and Wood Protection at the Federal Research Centre for Forestry and Forest Products in Hamburg, Germany. His work had a decisive influence on the development of wood anatomy, wood biology and dendrochronology and his laboratory was a reference point for dendrochronology worldwide. He supported dendrochronologists throughout Europe and around the world in their pioneering work to establish dendrochronology laboratories and develop dendrochronology in numerous countries, including Slovenia.

Six compartments of burnt areas from different years were studied in larch, pine-larch and larch-pine dwarf shrub-moss-lichen sparse forests and light forests of the Nadym district of the Yamal-Nenets Autonomous Okrug. The new dendroсhronological method of dating of forest fires based on indicators of a variation of parameters of width of year rings is used. It showed that all biocoenoses during the life of trees were repeatedly exposed to fires, which frequency on different areas makes from 1 to 3 in a century. The beginning of the growth of new generations of trees usually comes in the years following the passing of fires and coincides with the phase of enhanced post-fire growth of the surviving instances of older generations. On all of the examined burnt areas, there is a natural regeneration of tree plants: on fresh burns (prescription of the fire 2 years) it is represented only by a vegetatively renewing birch and its self-sowing; on old ones (prescription of the fires 12, 17 and 22 years old) – the undergrowth of conifers prevails. The total number of reliable undergrowth of tree plants of all species varies in different areas from 0.7 to 10.0 thousand pcs / ha. The total number of undergrowth with an increase in the age of burnt area decreases, and older generations begin to dominate in composition. This is due to the restoration of living ground cover, which prevents the germination of tree seeds. The composition of the undergrowth and the ratio of species in it is determined by the presence of seed trees. In sparse forests, where Scotch pine is present in the composition of the remaining stand, it regenerates better than the Siberian larch, which leads to a gradual change of larch stands to pine. If there are mature the Siberian stone pine trees on the site or near it, there is an active natural regeneration of this species in the burned area.

It has recently become a matter of discussion whether it is correct to use regional tree-ring chronologies in spatiotemporal climate reconstructions, since natural and climatic conditions in the regions may be heterogeneous, varying on different scales (from micro to global). We have studied the response of tree-ring width to climate in Scots pine (Pinus sylvestris L.) growing in the steppe zone, in insular pine forest of the Southern Urals and ribbon pine forests of Altai. Regional features and differences between the corresponding tree-ring chronologies obtained in the season of tree-ring formation (May–July) and spatiotemporal asynchrony in the long-term dynamics of tree-ring width in the study regions have been revealed. [ABSTRACT FROM AUTHOR]

Latewood width tree‐ring chronologies from arid‐site conifers in the southwestern United States are correlated with precipitation during portions of the summer monsoon season. The onset date and length of the monsoon season varies across the region, and these regional differences in summer rainfall climatology may impact the strength and timing of the warm season precipitation response of latewood chronologies. The optimal latewood response to summer precipitation is computed on a daily basis using 67 adjusted latewood chronologies (LWa) from the southwestern United States, adjusted to remove correlation with preceding earlywood growth. Most LWa chronologies are significantly correlated with precipitation summed over a period of approximately 4 weeks (29 days) in early summer. This early summer precipitation signal is present in most ponderosa pine chronologies across the study area. It is also evident in Douglas‐fir chronologies, but only from southern Arizona and New Mexico. The Julian date of summer precipitation onset increases from south to north in the instrumental precipitation data for the southwestern United States. The timing of the early summer season precipitation response in most LWa chronologies also tends to occur later in the summer from southeastern Arizona into northern New Mexico and eastern Colorado. Principal components analysis of the LWa chronologies reproduces two of the three most important spatial modes of early summer precipitation covariability seen in the instrumental data. The first PC of LWa is related to the same atmospheric circulation features associated with PC1 of instrumental early summer precipitation, including cyclonic circulation over the southwestern United States and moisture advection from the eastern Pacific. Correlation analyses between antecedent cool season precipitation and early summer rainfall using instrumental and tree‐ring reconstructed precipitation indicates that the tree‐ring data reproduce the multi‐decadal variability in correlation between seasons seen in the instrumental data. [ABSTRACT FROM AUTHOR]

The article analyzes tree-ring chronologies of contemporary pines growing on different hypsometric marks in relation to the modern level of the Andreevskoe lakes, on the low-ridges of terrace-like formations, floodplain lowlands and riams. The tree-ring chronologies from these areas, their correlation, dependence of the width of the rings on various natural factors, such as fires, harmful insects and fluctuation of groundwaters itself, reflecting the level of lakes in the Andreevskoe lake system are described. As a result of the study, 8 tree-ring chronologies were made, ecological and biological regularities were found out determining the formation of annual pine rings in the lake area due to a change in its level. The longest chronology of the lake coast for 197 years (since 1821) confirmed low water level in the lake, recorded on the map of surveyor Vasily Filimonov, created in November 1829. The use of chronologies was analyzed based on the difference in width of the annual pine rings according to the principle of contrasting biotopes (high — low, dryland — peatland), limited possibilities for reconstructions of this type based on individual ring chronologies are shown. A 174-year-old difference chronology (since 1843) was created, verified by a number of historical evidence, results of studies of lakes in the south of Western Siberia and cartographic material of the recent decades. The difference created chronology is recommended as a basis for reconstruction of the lake's level regime (possibly in combination with certain ring chronologies), although the fluctuation amplitudes can be specified for further dendrochronological reconstructions using old construction timber and fossil wood (in peat bogs).

The dynamics of radial wood increments have been analyzed according to the three tree-ring chronologies ALT (1463–2017), TUV (1715–2012), and MON (1663–2017) obtained for the southern regions of the Altai Mountains, southwestern regions of Tuva, and northern regions of Mongolian Altai, respectively. Chronologies demonstrate similar annual and long-term temporal variability. Cyclic changes in wood growth with periods of 10–14 and 29–33 years have been revealed. The limiting factor of growth is the air temperature in June–July (r > 0.7). At the same time, the chronologies are sensitive to the variation in circulatory, hydrological and glaciological parameters. [ABSTRACT FROM AUTHOR]

Prof. Dr. Dieter Eckstein (1939 - 2021) significantly influenced the global development of dendrochronology and the underlying science of wood biology. Eckstein's research areas included dendroclimatology, xylogenesis, ecophysiology, and quantitative wood anatomy. His personal and collaborative work continues to improve our understanding of both the natural environment and human cultural development. The techniques he developed and championed resolved long-standing difficulties in the application of tree-ring science to understand both natural processes and human effects on tree and forest development. As importantly, he nurtured and promoted both the careers and the lives of many fellow scholars and students around the world. Here we present a systematic bibliography of more than 280 publications that illustrates the development of tree-ring research in Europe and elsewhere throughout the almost 50 years of Eckstein's career. Throughout his scientific career, Eckstein pioneered, developed, and promoted research opportunities with his students and co-workers at the University of Hamburg and beyond. His greatest legacy for his students and colleagues, and which we are challenged to continue, is to continue to build the international spirit of a "dendrofamily". [ABSTRACT FROM AUTHOR]

Rainfall and river levels in the Amazon are associated with significant precipitation anomalies of opposite sign in temperate North and South America, which is the dominant mode of precipitation variability in the Americas that often arises during extremes of the El Niño/Southern Oscillation (ENSO). This co-variability of precipitation extremes across the Americas is imprinted on tree growth and is detected when new tree-ring chronologies from the eastern equatorial Amazon are compared with hundreds of moisture-sensitive tree-ring chronologies in mid-latitude North and South America from 1759 to 2016. Pan-American co-variability exists even though the seasonality of precipitation and tree growth only partially overlaps between the Amazon and mid-latitudes because ENSO forcing of climate can persist for multiple seasons and can orchestrate a coherent response, even where the growing seasons are not fully synchronized. The tree-ring data indicate that the El Niño influence on inter-hemispheric precipitation and tree growth extremes has been strong and stable over the past 258-years, but the La Niña influence has been subject to large multi-decadal changes. These changes have implications for the dynamics and forecasting of hydroclimatic variability over the Americas and are supported by analyses of the available instrumental data and selected climate model simulations.

We present a new 1104-year tree-ring chronology for south-eastern Tuva. The chronology was built based on larch samples (Larix sibirica Ldb.) of living trees and rests of the trunks from the upper timberline (2200-2300 m). Correlation coefficient analyses between tree-ring indices and weather station data revealed prevailing influence of June-July air temperature on tree growth variability. This allow to obtained summer temperature reconstruction for south-eastern Tuva during the last 800 years.

To study climate variability/change, the tree-ring width index chronologies of two species ( Cedrus deodara and Pinus roxburghii ) of the western Himalaya was determined. The first principal component (PC1) prepared using the three-site tree-ring width chronologies of the western Himalaya was found to be negatively correlated with the heat index and positively with the Palmer Drought Severity Index (PDSI) and moisture index from February to May as representative of the regional climate. The correlation coefficient of PC1 with the heat index, PDSI, and moisture index for the period 1901–1988 was estimated to be −0.60, 0.37, and 0.59, respectively, which were highly significant at 0.1% level. The result shows that increasing the heat index may enhance transpiration and evaporation over the western Himalaya, which may cause insufficient moisture at the root zone of the trees. Based on the tree-ring data, the heat index of spring season (February–May) was reconstructed back to AD 1839. The reconstructed heat index showed the longest warm periods during 1952–1963 and 1966–1976 in the 20th century. [ABSTRACT FROM AUTHOR]

Mexico has suffered a long history and prehistory of severe sustained drought. Drought over Mexico is modulated by ocean-atmospheric variability in the Atlantic and Pacific, raising the possibility for long-range seasonal climate forecasting, which could help mediate the economic and social impacts of future dry spells. The instrumental record of Mexican climate is very limited before 1920, but tree-ring chronologies developed from old-growth forests in Mexico can provide an excellent proxy representation of the spatial pattern and intensity of past moisture regimes useful for the analysis of climate dynamics and climate impacts. The Mexican Drought Atlas (MXDA) has been developed from an extensive network of 252 climate sensitive tree-ring chronologies in and near Mexico. The MXDA reconstructions extend from 1400 CE–2012 and were calibrated with the instrumental summer (JJA) self-calibrating Palmer Drought Severity Index (scPDSI) on a 0.5° latitude/longitude grid extending over land areas from 14 to 34°N and 75–120°W using Ensemble Point-by-Point Regression (EPPR) for the 1944–1984 period. The grid point reconstructions were validated for the period 1920–1943 against instrumental gridded scPDSI values based on the fewer weather station observations available during that interval. The MXDA provides a new spatial perspective on the historical impacts of moisture extremes over Mexico during the past 600-years, including the Aztec Drought of One Rabbit in 1454, the drought of El Año de Hambre in 1785–1786, and the drought that preceded the Mexican Revolution of 1909–1910. The El Niño/Southern Oscillation (ENSO) is the most important ocean-atmospheric forcing of moisture variability detected with the MXDA. In fact, the reconstructions suggest that the strongest central equatorial Pacific sea surface temperature (SST) teleconnection to the soil moisture balance over North America may reside in northern Mexico. This ENSO signal has stronger and more time-stable correlations than computed for either the Atlantic Multidecadal Oscillation or Pacific Decadal Oscillation. The extended Multivariate ENSO Index is most highly correlated with reconstructed scPDSI over northern Mexico, where warm events favor moist conditions during the winter, spring, and early summer. This ENSO teleconnection to northern Mexico has been strong over the past 150 years, but it has been comparatively weak and non-stationary in the MXDA over central and southern Mexico where eastern tropical Pacific and Caribbean/tropical Atlantic SSTs seem to be more important. The ENSO teleconnection to northern Mexico is weaker in the available instrumental PDSI, but analyses based on the millennium climate simulations with the Community Earth System Model suggest that the moisture balance during the winter, spring, and early summer over northern Mexico may indeed be particularly sensitive to ENSO forcing. Nationwide drought is predicted to become more common with anthropogenic climate change, but the MXDA reconstructions indicate that intense “All Mexico” droughts have been rare over the past 600 years and their frequency does not appear to have increased substantially in recent decades. [ABSTRACT FROM AUTHOR]

Variations in mountain snowpack in the western Canadian Cordillera have widespread and important impacts on ecosystems, environmental processes and socio-economic activities (e.g. water availability downstream). Historical records of snowpack generally span only the latter half of the 20th century offering a limited perspective on the causes and uniqueness of recently observed changes across the region. This paper explores the potential utility of a network of low elevation Douglas-fir ( Pseudotsuga menziesii) and ponderosa pine ( Pinus ponderosa) tree ring-width chronologies to reconstruct past snowpack variations. Correlation coefficients between the tree-ring chronologies and a set of snow water equivalent (SWE) records are calculated and mapped. Separate analyses were carried out for total ring- width (TRW) and partial-ring measurements (earlywood and latewood; EW and LW). A set of Adjusted LW chronologies was also developed; in these, the relationship between LW and the preceding EW width has been removed. The ring-width chronologies exhibit moderately strong relationships with SWE records from the western Canadian Cordillera and these relationships vary in sign across the region. Distinctive regional groups are identified where chronologies exhibit same-sign correlations with SWE, in possible accordance with the elevation and characteristics of the tree-ring chronology sample sites. The EW chronologies correlate more strongly and consistently with SWE records in regions where the growth relationship with SWE is negative. The LW chronologies, and particularly the Adjusted LW chronologies, exhibit a greater number of positive correlations with the set of SWE records. Collectively these results offer valuable insights for developing a targeted sampling and/or reconstruction strategy that can exploit these different relationships with SWE to generate more robust estimates of pre-instrumental snowpack for the region. [ABSTRACT FROM AUTHOR]

ABSTRACT Recent studies have pointed out the statistical occurrence of dual-season droughts detected in tree-ring chronologies over the southwestern US region that is not well described by instrumental observed records of the 20th century. In this study, a multi-statistical approach that evaluates persistent dual-season drought using a mode-of-variability oriented approach is proposed, considering a new network of tree-ring earlywood ( EW)- and latewood-adjusted ( LWadj) chronologies from throughout southwestern North America. To determine dominant patterns of spatiotemporal variability, empirical, orthogonal functions, canonical correlation analysis, and multi-taper-method singular value decomposition analyses were applied, with focus on variability from inter-annual to centennial periods and highlighting the multi-decadal signals inherent to proxy record network. During the instrumental period, we demonstrate that EW and LWadj networks of tree-ring chronologies are able to capture the associated precipitation responses of cool and warm season atmospheric teleconnections. Considering the four-century period of the complete tree-ring network, we explore the possibility of a dual summer-winter variability signal in the low-frequency climate regime. EW and LWadj seem to be coherent in-phase at the very low-frequency scale (50-100 years spectral band). This provocative result is supported by major historic documented multi-year droughts of the region since 1650. Thus, the temporal variation of these chronologies time series and its associated spatial pattern strongly suggest that this low-frequency mode might represents an important spatiotemporal variation of droughts in the Southwest; however, the source of this signal is still an open question and of great interest for drought planning and resource management in the region. [ABSTRACT FROM AUTHOR]

The study has assessed the interdecadal cyclicity in upper and lower tree-line growth variations in the tree-ring chronologies used to reconstruct the June-July air temperatures since 1715 with the Teeli meteorological station data and May-June water discharges of the Buyant River (Mongolia) since 1474. The cycle detection verification with the instrumental hydrometeorological data allowed us to come to a conclusion about the climatic causality of 21- to 45-year cyclic variations in tree-ring growth. [ABSTRACT FROM AUTHOR]

For the first time we identify the peculiarities of the effect of the most powerful (VEI > 5) volcanic eruptions on the regional climate of the Murmansk region on the basis of Kola Peninsula dendrochronological data for a period of more than 560 years. The analysis was based on the tree-ring chronology covering the period from 1445 to 2005. This chronology was derived from Pinus sylvestris samples collected near the northern tree line at Loparskaya station (68°37′ N; 33°14′ E). The data were processed using modern techniques adopted in dendrochronology (cross dating and standardization). We reveal a significant decrease in the radial tree-ring growth over 8 years (on average) after the eruptions; then its value is restored to the normal level. This finding will help evaluate the response of the regional climate system to external climate forcings in this economically important region for Russia. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Anderson, SallyRose, Glenn Tootle, and Henri Grissino-Mayer, 2012. Reconstructions of Soil Moisture for the Upper Colorado River Basin Using Tree-Ring Chronologies. Journal of the American Water Resources Association (JAWRA) 48(4): 849-858. DOI: 10.1111/j.1752-1688.2012.00651.x Abstract: Soil moisture is an important factor in the global hydrologic cycle, but existing reconstructions of historic soil moisture are limited. We used tree-ring chronologies to reconstruct annual soil moisture in the Upper Colorado River Basin (UCRB). Gridded soil moisture data were spatially regionalized using principal components analysis and k-nearest neighbor techniques. We correlated moisture sensitive tree-ring chronologies in and adjacent to the UCRB with regional soil moisture and tested the relationships for temporal stability. Chronologies that were positively correlated and stable for the calibration period were retained. We used stepwise linear regression to identify the best predictor combinations for each soil moisture region. The regressions explained 42-78% of the variability in soil moisture data. We performed reconstructions for individual soil moisture grid cells to enhance understanding of the disparity in reconstructive skill across the regions. Reconstructions that used chronologies based on ponderosa pines ( Pinus ponderosa) and pinyon pines ( Pinus edulis) explained more variance in the datasets. Reconstructed soil moisture data was standardized and compared with standardized reconstructed streamflow and snow water equivalent data from the same region. Soil moisture and other hydrologic variables were highly correlated, indicating reconstructions of soil moisture in the UCRB using tree-ring chronologies successfully represent hydrologic trends. [ABSTRACT FROM AUTHOR]

Studies in Central Asia (Altai-Sayan region, northwest and central Mongolia) have shown that trees growing in arid conditions of mountain forest-steppes have a mixed and unstable climatic response. It is obvious that this nature of the climatic response of trees prevents the use of tree-ring chronologies for climate reconstruction. In this connection, it is necessary to separate the climatic signal of tree-ring chronologies, i.e., extract the signal for moisture. This paper proposes a method for separating the climatic signal of tree-ring chronologies of mountain forest-steppes, and reports estimates of its reliability by two independent methods. Analysis of the chronologies obtained after separation of the signal, based on meteorological and hydrological data, has shown that these chronologies can be used for climate reconstructions. [ABSTRACT FROM AUTHOR]

The results of studies on the radial increment of larch and pine in central Yakutia are presented. The application of dendroclimatological methods to the study of tree-ring chronologies has made it possible to evaluate tree growth response to the dynamics of climatic factors over the past 120 years. The results of analysis of radial tree increment show that the onset of the growing season has shifted to earlier dates by the end of the 20th century. [ABSTRACT FROM AUTHOR]

Results of an investigation of radial growth of Larix cajanderi Mayr and Pinus sylvestris L. in Central Yakutia are presented. The time span of the constructed tree-ring chronologies is more than 200 years. Dendroclimatological analysis revealed a close relationship of tree growth on permafrost soils with climatic factors and soil hydrothermal conditions. A significant correlation of radial growth of larch and pine trees in Central Yakutia with soil temperature and moisture at various depths was found for the first time by statistical analysis. [ABSTRACT FROM AUTHOR]

Abstract: Tree-ring series collected from different parts of Arctic (Fennoscandia, Kola Peninsula and Northern Siberia) are investigated by means of the multi-taped method (MTM) of spectral analysis. Results of spectral analysis allow us to select the main periods of solar variability (22-, 30–33- and 80–90-year solar cycles) in Kola and Fennoscandia tree-ring chronologies. Besides it was found that only periodicities of around 20 years are present in Siberian and Stockholm series, respectively. With respect to 11-year periodicity, which is the most prominent one in sunspot number spectrum (Schwabe cycle) it may be said that it hardly appeared in Arctic tree-ring series. Although the 22-year cycles in climatic records are perceivable (it is also evident from our and other results), any physical mechanisms by which a reversal in the solar magnetic field could influence climate are still missing. To our mind, a potential cause of this phenomenon seems to be a variation of stardust flux inside the solar system. The most recent observations in frame of the DUST experiment on board the Ulysses spacecraft have shown that stardust level inside of the solar system was trebled during the recent solar maximum (Landgraf et al., 2003. Penetration of the heliosphere by the interstellar dust stream during solar maximum. Journal Geophysical Research 108, 8030). It is possible that the periodic increase of stardust in the solar system will influence the amount of extraterrestrial material that rains down to the Earth and consequently down to the Earth''s atmosphere and may affect climate through alteration of atmospheric transparency and albedo. [Copyright &y& Elsevier]

Abstract: Previous studies have used tree-ring chronologies from several species to develop reconstructions of precipitation, temperature, streamflow and glacier mass balance for sites in Banff National Park, Alberta. This study examines the variability in a >300-year summer streamflow reconstruction for the Bow River at Banff in conjunction with changes in the major contributors to streamflow (glacier melt, winter and summer pecipitation). Reconstructed winter mass balance for Peyto Glacier is used as a surrogate for winter precipitation and April–August precipitation is reconstructed for Banff. Streamflow variability correlates most highly with winter precipitation and periods of high flow follow above average snowfall in the previous winter (high winter balance) and in some cases also with above normal summer precipitation. A clear response to changes in summer mass balance at Peyto Glacier (i.e. summer glacier melting) cannot be identified in this summer discharge record. Problems developing physically realistic flow reconstructions for snowmelt dominated rivers from summer sensitive tree-ring chronologies are also discussed. [Copyright &y& Elsevier]

Abstract: Earlywood ring-width chronologies derived primarily from Douglas-fir trees were used to reconstruct winter–spring (November–May) precipitation and fall–spring (September–June) streamflow volumes for the period 1765–1993 in the forested upper Nazas watershed in Durango, Mexico. The tree-ring data were obtained from mixed conifer stands within or adjacent to the upper Nazas watershed. Precipitation data were derived from one of the longest regional records. The streamflow data were obtained from a guage located in the upper Nazas watershed. The Principal Component 1 (PC1) of nine residual earlywood chronologies accounted for 73% of the variance in November–May precipitation 1967–1993, and 64% for the total period with available data 1941–1993. The mean of three residual earlywood chronologies from Douglas-fir explained 51% of the normalized streamflow at Sardinas from 1971–1992. The 20th century was characterized by severe droughts, especially between 1950 and 1963 that also affected other regions of Mexico and the southwestern United States. Additional droughts of similar or greater magnitude occurred in the 1790s, 1810s, 1860–1870s and 1890–1910s. Similar periods of low flow occur in the September–June streamflow reconstruction between 1765 and 1993. These results indicate that tree-ring chronologies from this region document a high percentage of the precipitation and streamflow variance. Spectral analysis detected significant high periodicities in both records at peaks of 4 and 7 years that could be related to the ENSO frequency bands (approximately 4.0 and 6.25 years). Analysis of the reconstructed records show strong influence of ENSO on precipitation and streamflow amounts on an interannual basis. These results can provide significant inputs to decisions regarding management of water resources that are used to irrigate land in the Comarca Lagunera: specifically they indicate that water budgeting should be managed over longer time periods to account for this ENSO-related variability rather than on the year-to-year basis that is presently used. [Copyright &y& Elsevier]

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Thermokarst dynamics and their underlying causes are investigated and reconstructed on the basis of Muzhy weather station records (Western Siberia) of air temperature, precipitation and snow cover, and a tree-ring chronology analysis of Siberian stone pine (Pinus sibirica Du Tour). The results indicate that the development of thermokarst over the last 50 years has depended primarily on increasing precipitation rather than increasing air temperature. Reconstruction of past thermokarst borderlines shows that the rate of thermokarst expansion in the second half of the 20th century increased to 7.4 cm/year, as compared to past rates ranging from 4 to 8.1 cm/year. [Copyright &y& Elsevier]

The article discusses comparison of tree-ring chronologies and repeated timber inventories as forest monitoring tools. Topics discussed include dendrochronological data quantifying annual xylem growth of individual trees over whole life span, growth rates of large pines declined more than those of small pines, and systematic differences in absolute values of basal area increments computed from repeated forest inventories.

Improvement of dendrochronological crops yield reconstruction by separate application of earlywood and latewood width chronologies succeeded in rain-fed semiarid region. (1) Background: Tree-ring width chronologies have been successfully applied for crops yield reconstruction models. We propose application of separated earlywood and latewood width chronologies as possible predictors improving the fitness of reconstruction models. (2) Methods: The generalized yield series of main crops (spring wheat, spring barley, oats) were investigated in rain-fed and irrigated areas in semiarid steppes of South Siberia. Chronologies of earlywood, latewood, and total ring width of Siberian larch (Larix sibirica Ledeb.) growing in forest-steppe in the middle of the study area were tested as predictors of yield reconstruction models. (3) Results: In the rain-fed territory, separation of earlywood and latewood allowed increasing variation of yield explained by reconstruction model from 17.4 to 20.5%, whereas total climatic-driven component of variation was 41.5%. However, both tree-ring based models explained only 7.7% of yield variation in the irrigated territory (climate inclusion increased it to 34.8%). Low temperature sensitivity of larch growth was the main limitation of the model. A 240-year (1780–2019) history of crop failures and yield variation dynamics were estimated from the actual data and the best reconstruction model. (4) Conclusions: Presently in the study region, breeding of the environment-resistant crops varieties compensates the increase of temperature in the yield dynamics, preventing severe harvest losses. Tree-ring based reconstructions may help to understand and forecast response of the crops to the climatic variability, and also the probability of crop failures, particularly in the rain-fed territories. [ABSTRACT FROM AUTHOR]

In spite of enormous diversity in tree species, dendrochronological records in the tropical Andes are very scarce. Therefore, it is necessary to increase the search for new tree species with high dendrochronological characteristics in the tropical Andes, including the humid Puna of Peru. We present the first tree-ring chronology from Polylepis rodolfo-vasquezii , a recently described tree species in the Central Andes of Peru between 4000 and 4400 m elevation. Fifty trees were sampled in the district of Comas, Peru. After establishing the anatomical characteristics that delimit the annual growth rings, we developed a ring-width chronology by applying conventional dendrochronological techniques. The chronology covers the period 1869–2015 (157 years) and is well replicated from 1920 to present (> 20 samples). The statistics used to evaluate the quality of the chronology indicate that the P. rodolfo-vasquezii has similar values of MS, RBAR and EPS to those shown by other Polylepis spp chronologies. To determine the main climatic factors controlling the growth of P. rodolfo-vasquezii , we compared our chronology with local and regional temperature and precipitation records. Growth season temperature (November to May) seems to be the main climatic factor modulating inter-annual variations in the growth of this species. The sensitivity to inter-annual temperature variations highlights the potential of P. rodolfo-vasquezii to provide climatically sensitive dendrochronological records in the Central Andes. To our knowledge, this is the first tree-ring record in South America displaying significant relationships with temperature over the tropical Atlantic Ocean. [ABSTRACT FROM AUTHOR]

So-called annual banding has been identified in a number of speleothems in which the number of bands approximates the time interval between successive U-series dates. The apparent annual resolution of speleothem records, however, remains largely untested. Here we statistically compare variations in band thickness from a late Holocene stalagmite in Carlsbad Cavern, Southern New Mexico, USA, with three independent tree-ring chronologies form the same region. We found no correspondence. Although there may be various explanations for the discordance, this limited exercise suggests that banded stalagmites should be held to the same rigorous standards in chronology building and climatic inference as annually resolved tree rings, corals, and ice cores. [Copyright &y& Elsevier]