ALBERT

Description: Publication date: Available online 22 March 2016 Source: Dendrochronologia Author(s): Alexander Gradel, Christina Hänsch, Batsaikhan Ganbaatar, Batdorj Dovdondemberel, Ochirragchaa Nadaldorj, Björn Günther The mountain forest steppe and taiga in northern Mongolia have experienced a forest decline in area and quality since the end of the last century. Changes in land use, climate, fire frequency and pest occurrence are considered to be the main drivers of this vegetation shift and desertification. Because this region is the source for major rivers, is home to a unique flora and fauna and represents an important source of timber for Mongolia, the ability of different tree species to respond to these changes and regenerate is of increasing interest. Our contribution focuses on the climate-growth relationship of old and young birch trees from two valleys in the Mongolian province of Selenge Aimag. The research site Bugant, located in the Western Khentey Mountains, was the most important logging centre in Mongolia during socialist times. Today, the vegetation is dominated by succession forests of light taiga. The research site Altansumber, on the border of the Sant and Khushat soum, is dominated by light taiga and mountain forest steppe. Traditional nomads who depend on these forests for different reasons inhabit this area. Wood cores were sampled and chronologies of young and old birch trees at Bugant and Altansumber were created. Climate data were obtained from the Eroo station, which is known in the region for its long and reliable climate record. We analysed the climate-growth relationships of the chronologies from 1962 to 2009. At both sites and in both age classes, correlations with temperature were predominantly negative, particularly in April (Bugant, south- and east-facing slopes) and May (Altansumber, north-facing slopes). Precipitation of the late summer of the previous year (August/September) positively correlated with the growth of birch at Altansumber. We assume that the significant negative correlation between winter precipitation (December/January) and the growth of old birches at both sites is due to positive effects of snow cover on the survival rate of herbivorous insect populations. Our results indicate that during the early vegetation period, younger birch trees are more dependent on water availability than older ones. Negative pointer years were characterized by below-average precipitation during the current summer period and above-average spring temperatures. For the old trees, positive pointer years were characterized by above-average summer precipitation. We conclude that water availability is the most crucial factor for the growth of white birch in northern Mongolia.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Luke J. Amos-Binks, David A. MacLean We used dendrochronological analyses to identify periods of natural disturbance and resulting growth responses in 32 mixed species stands in the Acadian forest. Stands represented five different development patterns, based upon 1946 softwood (SW) content (70–80%, termed SW versus 30–60%, termed mixedwood (MW)) and change in SW content from 1946 to 2006: SW-stable, SW-declining, MW-fluctuating, MW-stable, and MW-declining. Standardized growth chronologies were developed from 1163 increment cores sampled from balsam fir ( Abies balsamea ), red spruce ( Picea rubens ), yellow birch ( Betula alleghaniensis ), and sugar maple ( Acer saccharum ). Growth chronologies clearly identified three spruce budworm ( Choristoneura fumiferana ) outbreaks from 1914 to 1921, 1954 to 1961, and 1975 to 1984, and birch dieback from 1938 to 1948. Stand developmental patterns were caused by species characteristics and multiple interacting disturbances, resulting in mortality, growth reductions, releases, and establishment of new cohorts. Balsam fir was present in all stands, but its tendency to establish and release from advanced regeneration following budworm-caused mortality resulted in cyclical proportions of fir in the canopy. Red spruce was less vulnerable to spruce budworm and longer lived, allowing them to persist and better withstand disturbance. Periodic growth index values less than 0.9 for fir and spruce were correlated with mortality of softwoods caused by defoliation, which resulted in release and growth index values >1.1 for sugar maple. Our results demonstrated substantial variation in mixedwood development patterns over a 60-year period within a small (45 km) area.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Terje Thun, Helene Svarva Nineteen Norwegian grain chests made of Scots pine ( Pinus sylvestris L.) were analyzed by measuring tree-ring widths on photographs and scanned pictures. Seventeen of the chests were successfully dated by dendrochronology. Two of the dates are corrections of an earlier dating; the ages of these two chests were verified by radiocarbon dating. The grain chests were expected to be medieval, but four, all without carvings, proved to be post-medieval. The mean curve constructed from the dated chests matches all regional Scots pine chronologies in central and southern Norway and several from southern Sweden. All the chests were probably constructed in central Norway. Originally only sixteen chests were known, but several new ones were discovered in the course of this project.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Marcelo Pablo Chartier, María Alejandra Giantomasi, Daniel Renison, Fidel Alejandro Roig Soil erosion is a serious problem of land degradation in many parts of the world, and particularly in mountain rangelands. To understand this process it is necessary to develop methods to assess soil erosion rate in a quick, economic and accurate manner. Based on the analysis of exposed Polylepis australis roots, we tested a dendrogeomorphological method for determining soil loss rate in rills and gullies. Few studies considered non-coniferous tree rings in soil erosion analysis and we used, for the first time, an experimental procedure of root exposure and provided a comparison with roots exposed by gully erosion. Our main results showed that as a consequence of soil erosion, exposed roots changed from root-like to a more stem-like wood anatomical structure. The percentage of vessel area per tree-ring area decreases by an average of 22% to 43% during the first and second year after exposure, respectively. Moreover, and during the same time interval, the mean vessel area decreased 32% and 65%, and the number of vessels increased 7% and 48%, respectively. Scars formed at the upper side of the exposed roots are coincident with changes in wood anatomy, and both evidences may be applied to reconstruct an erosion process. This study confirms that the wood anatomy analysis of partially exposed roots can be used to determine the year in which roots are exposed and provides a useful tool to monitor soil erosion rates with a high accuracy.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): P. Šamonil, J. Timková, I. Vašíčková The use of individual-based models in the study of the spatial patterns of disturbances has opened new horizons in forest ecosystem research. However, no studies so far have addressed (i) the uncertainty in geostatistical modelling of the spatial relationships in dendrochronological data, (ii) the number of increment cores necessary to study disturbance spatial patterns, and (iii) the choice of an appropriate geostatistical model in relation to disturbance regime. In addressing these issues, we hope to contribute to advances in research methodology as well as to improve interpretations and generalizations from case studies. We used data from the beech-dominated Žofínský Prales forest reserve (Czech Republic), where we cored 3020 trees on 74 ha. Block bootstrap and geostatistics were applied to the data, which covered five decades with highly different disturbance histories. This allowed us to assess the general behavior of various mathematical models. Uncertainty in the spatial patterns and stability of the models was measured as the length of the 95% confidence interval (CI) of model parameters. According to Akaike Information Criterion (AIC), the spherical model fitted best at the range of ca. 20 m, while the exponential model was best at the range of ca. 60 m. However, the best fitting models were not always the most stable. The stability of models grew significantly with sample size. At 〈500 cores the spherical model was the most stable, while the Gaussian model was very unstable at 〈300 cores. The pure nugget model produced the most precise nugget estimate. The choice of model should thus be based on the expected spatial relations of the forest ecosystem under study. Sill was the most stable parameter, with an error of ±6–20% for ≥1110 core series. By contrast, practical range was the most sensitive, with an error of at least ±59%. The estimation of the spatial pattern of severe disturbances was more precise than that of fine-scale disturbances. The results suggest that with a sample size of 1000–1400 cores and a properly chosen model, one reaches a certain precision in estimation that does not increase significantly with growing sample size. It appears that in temperate old-growth forests controlled by fine-scale disturbances, it is necessary to have at least 500 cores to estimate sill, nugget and relative nugget, while to estimate practical range at least 1000 cores are needed. When choosing the best model, the stability of the model should be considered together with the value of AIC. Our results indicate the general limits of disturbance spatial pattern studies using dendrochronological and geostatistical methods, which can be only partially overcome by sample size or sampling design.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): L. Dinis, M.M. Savard, P. Gammon, C. Bégin, J. Vaive This study investigates Pb isotope ratios at low concentrations (parts per billion; ppb) in tree rings and soils in the Northern Athabasca Oil Sands Region (NAOSR), western Canada, to evaluate if: (1) climatic conditions influence on tree-ring Pb assimilation; and (2) such low Pb content allows inferring the regional Pb depositional history. Our results reflect the influence of winter snow cover and the importance of minimum temperature and precipitation in spring and summer on the bioavailability of Pb and its passive assimilation by trees in sub-arctic semi-humid climatic conditions. Winter conditions can influence the state of root systems that subsequently impacts the following growth period, while spring and summer conditions likely control microbial processes and water source, and may thus impact Pb assimilation by trees. Thus, the results of tree-ring Pb concentrations show interesting correlation with cumulated snow from November of the previous year to February ( ρ = 0.53; P 〈 0.01; n = 36). Likewise, the 206 Pb/ 207 Pb ratios inversely correlate with minimum temperature from April to September ( ρ = −0.67; P 〈 0.01; n = 40) and precipitation from May to August ( ρ = −0.42; P 〈 0.01; n = 36). The isotopic results also suggest that the effects of climatic variations are superimposed by regional industrial Pb deposition: Western North American Aerosols (WNAA) and fugitive dust from the oil sands mining operations appear to be the most likely sources. Importantly, this study suggests that even at low Pb concentrations, tree-ring Pb isotopes are modulated by climatic conditions and potential input of regional and long-range transport of airborne Pb. These interpretations open the possibility of using Pb isotopes as an environmental tool for inferring the pollution history in remote regions, and improving our understanding of its natural cycle through the forest environment.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Douglas J. Stevenson, Thomas B. Lynch, Pradip Saud, Robert Heineman, Randal Holeman, Dennis Wilson, Keith Anderson, Chris Cerny, James M. Guldin Each year severe winter storms (≈ice storms) damage trees throughout the southern USA. Arkansas and Oklahoma have a history of severe winter storms. To extend that history back beyond the reach of written records, a distinctive tree ring pattern or signature is needed. Storm-caused breakage, branch loss and bending stress provide that signature. We found a severe storm signature in shortleaf pine ( Pinus echinata ). We used three published site chronologies, a set of five new site chronologies from a growth-and-yield study conducted by Oklahoma State University and the unpublished Shortleaf Canyon chronology from a master’s thesis at the University of Arkansas. Our method is based on two ring width values for the first and second growing seasons after the storm standardized to the ring widths of the seven growing seasons after the storm. Concordance between storm years predicted by tree ring patterns and actual storm years was tested using Cohen’s Kappa. Concern about confounding of ice storm signals by droughts led us to test concordance between severe storms and drought in July, August and September; results were inconclusive but stand as a warning that these two phenomena cannot be distinguished with certainty in the tree ring record. Damaging severe storms occurred in about 2.8% of all years. Two out of three storms identified as “severe” produced glaze icing.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Julieta Gabriela Arco Molina, Martín Ariel Hadad, Daniel Patón Domínguez, Fidel Alejandro Roig Frost events may damage the cambium and consequently the newly produced tracheids whose cell walls have not yet completed their lignifications, leading to the formation of frost rings. This study deals with the presence of frost rings in Araucaria araucana trees according to cambial age and bark thickness, under the assumption that these factors may be involved in physical or physiological mechanisms that increase resistance to freezing temperatures that impact the cambial tissue. The study was conducted in northern Patagonia at two sites of contrasting geomorphology, and therefore potentially associated with a differential degree of exposure to extreme cold. Wood plus bark cores were extracted from main stems at two heights from the ground and from each of the four cardinal point directions for 30 individuals per site. A Linear Mixed Model and a Generalized Linear Mixed Model were applied in order to relate the bark thickness and the frequency of frost rings in accordance with the different sampling points on the stem. It was observed that as bark becomes thicker with cambial age, the frequency of frost rings decreases, indicating a possible thermal-induced mechanism of bark protection. Consequently, there is an increase in the presence of frost rings at the younger stages of tree life. Although the mechanisms of cold hardiness in trees can be complex, including aspects of the tree physiology, our data indicated that as tree age increases, the thickness of the bark is higher, resulting in a potential effect of isolation and passive protection against the harmful effects of frosts. This mechanism may be relevant in the ecology, conservation and management of forests faced with extreme variability in future climate and changing scenarios.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Dominik Florian Stangler, Martin Mann, Hans-Peter Kahle, Elena Rosskopf, Siegfried Fink, Heinrich Spiecker Studying intra-annual wood formation dynamics provides valuable information on how tree growth and forests are affected by environmental changes and climatic extreme events. This study has the aim to evaluate and to quantify synergetic potentials emerging from a combination of current state of the art techniques used to monitor intra-annual wood formation processes. Norway spruce trees were studied in detail during the growing season 2009 with weekly sampling of microcores, high resolution point-dendrometers and wood anatomical analysis. The combination of the applied techniques allowed us to convert the spatial scales of radial tracheid diameter profiles to seasonal time scales and to synchronize fluctuations in intra-annual cell diameter profiles. This spatiotemporal information was used to validate the recently introduced software MICA ( Multiple interval-based curve alignment ) . In comparison to the conventional approach of averaging profiles of tree ring variables, the MICA aligned profiles exhibit a significantly higher synchronicity of the averaged data points. We also demonstrate two new features in the MICA application that enable to extrapolate spatiotemporal information between intra-annual profiles for the construction of robust mean (consensus) profiles that are representative for the population dynamics. By using a set of complementary techniques in an integrated approach, this study highlights a new methodological framework that can contribute to a better understanding of the environmental control of wood formation during the growing season.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Filipe Campelo, Cristina Nabais, Ana Carvalho, Joana Vieira Here we present the package tracheideR to standardize profiles of tracheid features, using the R computing environment. This package contains a collection of functions to transform the raw data obtained from image analysis into a tracheidogram to better visualize the radial intra-ring variation of histometric parameters. This procedure is crucial when estimating past weather conditions with a sub-annual resolution, since tracheidograms reflect the influence of fluctuations in weather conditions throughout the growing season (such as temperature and soil water content). The main function of this package is tracheider , which takes as input raw tracheidograms and standardizes them using three different methods. The first method standardizes the number of tracheids from different radial files to the mean number of cells, allowing that different annual rings have different number of cells. The second method normalizes the number of cells of different annual rings to the same number. Finally we present a new method to standardize histometric parameters considering the relative position of the cells within the tree ring. This package was tested using two rings of Pinus pinaster to demonstrate variations between the three methods. According to our results species with high intra- and inter-annual variability, as shown by conifers species growing under Mediterranean climate, should be standardized using the “relative position” method. Finally, we suggest that this new method should be applied to other species to check its potential to detect intra-ring fluctuations in tracheid features and to improve our capacity to detect intra-annual climatic signals.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Paolo Cherubini

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Jean-Philippe Martin, Daniel Germain Dendrogeomorphology has been recognized as a useful tool to reconstruct past snow avalanche chronologies, especially in remote areas where archives are non-existent. In recent years, there have been a multiplicity of snow avalanche studies based on tree-ring analysis. Yet, the dendrogeomorphic procedure applied to snow avalanches still lacks consensus within the scientific community. This paper illustrates four issues regarding this method encountered on a dataset encompassing 293 trees sampled from 4 sites in the White Mountains (New Hampshire, United States). (1) Separating a sample in an upslope and downslope subgroup allowed to reconstruct a more thorough avalanche chronology. (2) On the other hand, a strong response at a site sheltered from any avalanche track was attributed to extreme snow loadings with a return period well above 100 years. (3) In addition to climatic disturbances, ecological disturbances such as windthrows can cause an anatomical response in the trees similar to snow avalanches. An avalanche track might act as a wind tunnel, making the underlying runout zone a suitable site to windfalls. Sampling in transects can assist in determining the limit between avalanche-related and wind-related disturbances. (4) Early-spring torrential floods and avalanche activities at a multi-process site exhibit distinct spatial patterns in the dendrogeomorphological response that allow discrimination between the two processes in the reconstruction of past chronologies. While the dendrogeomorphologist should be cautious of these issues, their acknowledgement is an opportunity to understand the interactions between the different ecological, climatic and geomorphological processes operating on the forested slopes in the alpine–subalpine environment.

Description: Publication date: Available online 23 February 2016 Source: Dendrochronologia Author(s): Irina P. Panyushkina, Alexei A. Karpukhin, Asya V. Engovatova Investigations of interactions between climate change and humans suffer from the lack of climate proxies directly linked to historical or archaeological datasets that describe past environmental conditions at a particular location and time. We present a new set of pine tree-ring records ( Pinus sylvestris L.) developed from burial timbers excavated at the historical center of Yaroslavl city, Russia. A 171-year δ 13 C tree-ring chronology from AD 1430 to AD 1600 evidences mostly wet summers during the 15th century but exceptionally dry conditions of the 16th century at the Upper Volga catchment. According to the tree-ring record there were four major droughts (〈−1.5 σ ) lasting from 9 to 26 years: 1501–1517, 1524–1533, 1542–1555 and 1570–1596, and major pluvials (>+1.5 σ ) lasting from 70 to 5 years: 1430–1500, 1518–1523, 1534–1541, and 1556–1564. We discuss a plausible contribution of these droughts to crop failures and city fires documented with historical chronicles for the Upper Volga catchment. The devastating drought regime of the 16th century corresponds to the loss of independence of the Yaroslavl principality to the Grand Duchy of Moscow and the formation of the centralized Russian State during the reign of Ivan the Terrible (1533–1584) underpinning the emergence of the Russian Empire. This study substantiates the value of archaeological timbers from the oldest Russian cities and inclusion of stable carbon isotope analysis for understanding hydroclimatic regimes across the mid latitudes of East European Plain, and their relationship to the history of Russia. Graphical abstract

Description: Publication date: Available online 4 February 2016 Source: Dendrochronologia Author(s): James H. Speer, Achim Bräuning, Qi-Bin Zhang, Kambiz Pourtahmasi, Narayan P. Gaire, Binod Dawadi, Prabina Rana, Yub Raj Dhakal, Ram Hari Acharya, Dhruba Lochan Adhikari, Shankar Adhikari, Prakash Chandra Aryal, Damodar Bagale, Binod Baniya, Sanjaya Bhandari, Navin Dahal, Suchana Dahal, Narmandakh Ganbaatar, Anjana Giri, D.B Gurung, Yeshey Khandu, Binu Maharjan, Rajan Maharjan, Rayees Ahmad Malik, Cheryl D. Nath, Bikash Nepal, Justine Ngoma, Ramesh Pant, Mitra Lal Pathak, Hari Paudel, Bimal Sharma, Md Sarwar Hossain, Bayarbaatar Soronzonbold, Thida Swe, Ichchha Thapa, Achyut Tiwari The fieldweek associated with the 4th Asian Dendrochronological Association Conference was an excellent opportunity for education, networking, and research. The participants and group leaders worked together for five days in an area that was new to some of the group leaders and new to some of the participants which enabled us to learn about forest ecology around Kathmandu and Nagarkot, Nepal. The fieldweek was an excellent networking opportunity and the group leaders and participants bonded which strengthened international research in dendrochronology and continues to foster new research collaborations. All of the group leaders and participants had the opportunity to learn about tree-ring formation in Pinus roxburghii at 1500 masl elevation, to explore its wood anatomy, and to examine specific research questions in our field area. In the end we developed a better understanding of the stand-age structure of a stand of trees in Nagarkot, explored the erosion history from exposed roots, and investigated tree health issues on closely related sites. We found that P. roxburghii poses some dating issues with false and micro rings at this elevation, but we were still able to develop a tree-ring chronology from this species and make preliminary assessments of stand dynamics and health.

Description: Publication date: Available online 15 March 2016 Source: Dendrochronologia Author(s): Ekaterina Dolgova Although long-lived trees grow in the Northern Caucasus, no single tree-ring chronology has been reported thus far from this area in the International Tree-Ring Data Base (ITRDB), neither has one been published in international journals. Extensive tree-ring studies were conducted over the last decade, and a tree-ring network was developed for the investigated area. The data on the minimum blue intensity based on 33 series of pine ( Pinus sylvestris L.) and fir ( Abies nordmanniana (Steven) Spach) is presented in this study. The minimum blue intensity (BI) chronology covers the period 1596–2011 with EPS value ≥0.85. The BI chronology strongly correlates with the mean June-September temperature (R = 0.74; p 〈 0.05) from the weather station “Kluhorskij Pereval” (1951–2011). Mean June-September temperature anomalies were reconstructed using the rescaling method. Based on the reconstruction provided in this study the twentieth century is characterized by highly increased June-September temperature. According to this study, the minimum blue intensity approach demonstrates a great potential for paleoclimatic research in the Caucasus. Vast spatial coverage of the new BI-based reconstruction based on data from only two locations in the Northern Caucasus provides prospects for reconstruction of temperature variations for a great region in the Middle East and Northern Africa.

Description: Publication date: Available online 14 December 2015 Source: Dendrochronologia Author(s): Anna V. Taynik, Valentin V. Barinov, Orlan Ch. Oidupaa, Vladimir S. Myglan, Frederick Reinig, Ulf Büntgen Tree-ring research in the Altai-Sayan Mountains so far only considered a limited number of well-replicated site chronologies. The dendroecological and palaeoclimatological potential and limitations of large parts of south-central Russia therefore remain rather unexplored. Here, we present a newly updated network of 13 larch ( Larix sibirica Ldb.) tree-ring width (TRW) chronologies from mid to higher elevations along a nearly 1000 km west-to-east transect across the greater Altai-Sayan region. All data were sampled between 2009 and 2014. The corresponding site chronologies cover periods from 440 to 860 years. The highest TRW agreement is found between chronologies ≥2200 m asl, whereas the material from lower elevations reveals overall less synchronized interannual to longer-term growth variability. While fluctuations in average June–July temperature predominantly contribute to the growth at higher elevations, arid air masses from Mongolia mainly affect TRW formation at lower elevations. Our results are indicative for the dendroclimatological potential of the Altai-Sayan Mountains, where both, variation in summer temperature and hydroclimate can be robustly reconstructed back in time. These findings are valid for a huge region in central Asia where reliable meteorological observations are spatially scarce and temporally restricted to the second half of the 20th century. The development of new high-resolution climate reconstruction over several centuries to millennia will further appear beneficial for timely endeavors at the interface of archaeology, climatology and history.

Description: Publication date: November 2015 Source: Dendrochronologia, Volume 36 Author(s): Maryann R. Pirie, Anthony M. Fowler, Christopher M. Triggs Knowing the number of rings from the pith to the last cross-dated ring on incremental cores is important for regional curve standardisation, for constructing the best chronology by excluding rings formed when the tree was young, and for forest stand dynamics and regeneration studies. As the pith is rarely present on the samples an estimate of the distance to the pith is required. The aim of this paper is to assess the accuracy of three commonly used pith offset estimation methods for estimating pith offsets from kauri incremental cores. Literature identifies three main approaches for estimating pith offsets: Duncan’s geometric method, the concentric circles method (CCM), and the radius–length method. The accuracy of geometric and CMM were assessed using virtual cores constructed from an Agathis australis (Kauri) cross-section. Then the estimates for all three methods were applied to a subset of the kauri incremental cores database. The most accurate method for estimating the pith offset for kauri trees was found to be geometric method, followed by CCM. However, these approaches could only be used to estimate the pith offset for a few cores as they require the core to pass close enough to the pith that there is visible curvature on the cores. For most cores the radius–length method is the only method available for estimating the pith offset. This method relies on the assumption that the pith is located at the geometric centre of the tree which may not be a valid assumption for some species.

Description: Publication date: Available online 11 January 2016 Source: Dendrochronologia Author(s): Lena Hellmann, Leonid Agafonov, Olga Churakova (Sidorova), Elisabeth Düthorn, Ólafur Eggertsson, Jan Esper, Alexander V. Kirdyanov, Anastasia A. Knorre, Pavel Moiseev, Vladimir S. Myglan, Anatoly N. Nikolaev, Frederick Reinig, Fritz Schweingruber, Olga Solomina, Willy Tegel, Ulf Büntgen Arctic driftwood represents a unique proxy archive at the interface of marine and terrestrial environments. Combined wood anatomical and dendrochronological analyses have been used to detect the origin of driftwood and may allow past timber floating activities, as well as past sea ice and ocean current dynamics to be reconstructed. However, the success of driftwood provenancing studies depends on the length, number, and quality of circumpolar boreal reference chronologies. Here, we introduce a Eurasian-wide high-latitude network of 286 ring width chronologies from the International Tree Ring Data Bank (ITRDB) and 160 additional sites comprising the three main boreal conifers Pinus , Larix , and Picea . We assess the correlation structure within the network to identify growth patterns in the catchment areas of large Eurasian rivers, the main driftwood deliverers. The occurrence of common growth patterns between and differing patterns within catchments indicates the importance of biogeographic zones for ring width formation and emphasizes the degree of spatial precision when provenancing. Reference chronologies covering millennial timescales are so far restricted to a few larch sites in Central and Eastern Siberia (eastern Taimyr, Yamal Peninsula and north-eastern Yakutia), as well as several pine sites in Scandinavia, where large rivers are missing though. The general good spatial coverage of tree-ring sites across northern Eurasia indicates the need for updating and extending existing chronologies rather than developing new sites.

Description: Publication date: Available online 4 February 2016 Source: Dendrochronologia Author(s): Achyut Tiwari, Ze-Xin Fan, Alistair S. Jump, Shu-Feng Li, Zhe-Kun Zhou Population structure and tree recruitment dynamics in the natural treeline ecotone of high mountains are strong indicators of vegetation responses to climate. Here, we examined recruitment dynamics of Abies spectabilis across the treeline ecotone (3439–3638 m asl) of Chimang Lekh of Annapurna Conservation Area in the Trans-Himalayan zone of central Nepal. Dendrochronological techniques were used to establish stand age structure by ring counts of adults, and by terminal bud scar count for seedlings and saplings. The results showed abundant seedling recruitment, higher regenerative inertia and colonization with a consistent range shift of the A. spectabilis treeline. The upward expansion of this sub-alpine treeline was found to be driven by a strong dependence of seedling recruitment and radial growth on snowmelt and precipitation as temperatures rise. The radial growth of A. spectabilis at the alpine timberline ecotone (ATE) and closed timberline forest (CTF) showed sensitivity to spring season (March–May) climate. Tree ring indices of CTF showed a strong positive correlation with spring and annual precipitation, and a significant negative correlation with spring and annual temperature, however, moisture sensitivity was less strong at ATE than CTF.

Description: Publication date: Available online 31 December 2015 Source: Dendrochronologia Author(s): Olga V. Churakova (Sidorova), Aleksandr V. Shashkin, Rolf T.W. Siegwolf, Renato Spahni, Thomas Launois, Matthias Saurer, Marina V. Bryukhanova, Anna V. Benkova, Anna V. Kuptsova, Philippe Peylin, Eugene A. Vaganov, Valerie Masson-Delmotte, John Roden Tree-ring width and stable isotopic composition are widely used for the reconstruction of environmental conditions. Eco-physiological models simulating δ 13 C and δ 18 O provide tools to constrain the interpretation of measured tree-ring variations and their relationships to environmental variables. Here, we apply biochemical models of photosynthesis and a model of stomatal conductance to simulate the intra-annual dynamics of δ 13 C values in photo assimilates and tree-rings. We use these models to investigate the physiological responses of larch trees growing on permafrost to variability in precipitation and permafrost depth associated with regional temperature and precipitation changes. Tree-ring width, δ 13 C and δ 18 O in wood and cellulose were measured in larch ( Larix cajanderi Mayr.) samples from northeastern Yakutia (69°N, 148°E) for the period from 1945 to 2004 and used for comparisons with modeled δ 13 C and δ 18 O data. Mechanistic models that quantify physical and biochemical fractionation processes leading to oxygen isotope variation in organic matter are used to identify source water for trees growing on permafrost in Siberia. These models allowed us to investigate the influence of a variety of climatic factors on Siberian forest ecosystem water relations that impact isotope fractionation. Based on δ 13 C and δ 18 O in tree wood and cellulose measurements as well as outputs from different eco-physiological models, we assume that larch trees from northeastern Yakutia can have limited access to the additional thawed permafrost water during dry summer periods.

Description: Publication date: Available online 20 October 2015 Source: Dendrochronologia Author(s): Vladimir V. Shishov, Ivan I. Tychkov, Margarita I. Popkova, Viсtor A. Ilyin, Marina V. Bryukhanova, Alexander V. Kirdyanov It is generally assumed in dendroecological studies that annual tree-ring growth is adequately determined by a linear function of local or regional precipitation and temperature with a set of coefficients that are temporally invariant. However, various researchers have maintained that tree-ring records are the result of multivariate, often nonlinear biological and physical processes. To describe critical processes linking climate variables with tree-ring formation, the process-based tree-ring Vaganov–Shashkin model (VS-model) was successfully used. However, the VS-model is a complex tool requiring a considerable number of model parameters that should be re-estimated for each forest stand. Here we present a new visual approach of process-based tree-ring model parameterization (the so-called VS-oscilloscope) which allows the simulation of tree-ring growth and can be easily used by researchers and students. The VS-oscilloscope was tested on tree-ring data for two species ( Larix gmelinii and Picea obovata ) growing in the permafrost zone of Central Siberia. The parameterization of the VS-model provided highly significant positive correlations ( p 〈 0.0001) between simulated growth curves and original tree-ring chronologies for the period 1950–2009. The model outputs have shown differences in seasonal tree-ring growth between species that were well supported by the field observations. To better understand seasonal tree-ring growth and to verify the VS-model findings, a multi-year natural field study is needed, including seasonal observation of the thermo-hydrological regime of the soil, duration and rate of tracheid development, as well as measurements of their anatomical features.

Description: Publication date: Available online 30 October 2015 Source: Dendrochronologia Author(s): Vladimir Matskovsky, Andrey Dolgikh, Konstantin Voronin Dendrochronology is usually the only method of precise dating of unsigned art objects made on or of wood. It has a long history of application in Europe, however in Russia such an approach is still at an infant stage, despite its cultural importance. Here we present the results of dendrochronological and radiocarbon accelerated mass spectrometry (AMS) dating of three medieval icons from the 15th–17th century that originate from the North of European Russia and are painted on wooden panels made from Scots pines. For each icon the wooden panels were dendrochronologically studied and five to six AMS dates were made. Two icons were successfully dendro-dated whereas one failed to be reliably cross-dated with the existing master tree-ring chronologies, but was dated by radiocarbon wiggle-matching. Wiggle-matching of radiocarbon dates is the most promising method for dating Russian icons in the absence of a dense dendrochronological network. However, for this case uncertainties connected with the radiocarbon method have to be taken into account and further studies of these uncertainties must be undertaken by comparing dendro-dated and radiocarbon-dated wooden works of art. Our results, moreover, showed that in two cases art-historical dates were by five to ten decades older than the earliest possible time of the creation of the icons, based on dendrochronology.

Description: Publication date: Available online 6 June 2016 Source: Dendrochronologia Author(s): A. Papadopoulos Central Greece is the distribution common area of the endemic fir species Abies cephalonica and Abies borisii-regis . Forests fires and fir decline are some of the problems both species encountered during the past decades, with these problems being exacerbated lately by climate change. The present research investigates tree-ring patterns and climate responses of three fir populations along a latitudinal gradient in Central Greece. All three populations were homogeneous in their dendrometric, silvicultural and site characteristics but were phenotypically different. The analysis of tree-ring widths site chronologies revealed that 59% of their variability interprets common tree-ring patterns whereas another 25% interprets their differences as they appear from a south to north direction. This variability in tree-ring widths is proportional to the variability observed for precipitation, temperature and drought from a south to north direction in this region. The tree-ring to climate relationships revealed that the main climatic factor affecting fir tree-ring width is late spring and summer precipitation to which is positively correlated. Also, tree-ring widths were positively affected by the temperatures of the October and April before the growing season. However, June drought adversely affected tree-ring widths of the northern site while it positively affected them at the beginning of the spring season, especially for the southern site and in September for the northern sites. All dendrochronological statistics, tree-ring patterns and climate-growth relationships show a south to north trend following the climatic and phenotypic (species) variation observed to the same direction for fir populations in Central Greece.

Description: Publication date: Available online 7 June 2016 Source: Dendrochronologia Author(s): Kapoury Sanogo, Aster Gebrekirstos, Jules Bayala, Grace B. Villamor, Antoine Kalinganire, Soro Dodiomon This study aimed to investigate the applicability of dendrochronology for assessing the growth dynamics and response to climate variability and to estimate the aboveground carbon stock and carbon sequestration potential of Vitellaria paradoxa in southern Mali. Twenty stem disks were collected from three land-use types (parklands, fallows and protected areas) in Koutiala and Yanfolila districts. We combined a standard dendrochronological approach with biomass allometric equations to estimate the growth and carbon stocks. The results showed that V. paradoxa forms distinct growth ring boundaries but most of the disks from parklands did not successfully cross-date due to management operations like pruning. The tree-ring width showed a significant standardized coefficient of regression with rainfall (r 2 = 0.66, p 〈 0.001) but insignificant correlation with temperature. One-way analysis of variance showed no significant difference (p > 0.05) for C-sequestration as well as for carbon stocks in aboveground biomass for both land-use types and sites. Mean values of the amount of C-sequestered were 1.13 ± 0.63 Mg C ha −1 yr −1 in parklands, 0.93 ± 0.50 Mg C ha −1 yr −1 in fallows 0.66 ± 0.43 Mg C ha −1 yr −1 in the protected areas in Yanfolila. In Koutiala, the values were 0.73 ± 0.40 Mg C ha −1 yr −1 in the parklands and 0.67 ± 0.52 Mg C ha −1 yr −1 in the fallows. These results clearly indicate that dendrochronology can be applied to assess growth and carbon sequestration potential of V. paradoxa . These results also suggest that climate change could affect the growth and carbon sequestration potential of V. paradoxa . Given the limited size of our sample, figures on the amount of carbon are indicative calling for applying the tested approaches to larger samples and also to other tree species in West Africa.

Description: Publication date: Available online 8 June 2016 Source: Dendrochronologia Author(s): Ruibo Zhang, Yujiang Yuan, Xiaohua Gou, Tongwen Zhang, Chen Zou, Chunrong Ji, Ziang Fan, Li Qin, Huaming Shang, Xinjian Li Schrenk spruce ( Picea schrenkiana Fisch. et Mey.) is widely distributed in the Tianshan Mountains. In this study, four Schrenk spruce trees were continuously monitored with dendrometers from 27 April to 30 September 2014 on the northern slopes of the Tianshan Mountains in northwest China. The goal of this monitoring study was to determine the main growing season of Schrenk spruce and to analyze intra-annual radial growth variability and its relation to daily meteorological factors. Our studies have shown that the critical growing season of Schrenk spruce is from late May to late July and that the rapid growth stage is from mid-June to early July. Meanwhile, in the growing season, changes in the radial growth of Schrenk spruce were negatively correlated with daily temperature, evaporation, sunshine hours and vapor pressure deficit (VPD), and were positively correlated with precipitation and relative humidity (RH). The correlation coefficient between radial growth and RH can be as high as 0.750 (Pearson, p 〈 0.0001, n = 60). Dates in which precipitation occurred corresponded to periods of rapid growth. The results of the climate-growth analysis show that changes in radial growth reflect the effect of water stress on tree growth, whether or not the changes are positively or negatively correlated with the above climatic factors. This indicates that moisture plays a major role in the growth of Schrenk spruce. We suggest that precipitation between late May to late June is a limiting factor for radial growth of Schrenk spruce on the northern slopes of the Tianshan Mountains.

Description: Publication date: Available online 7 June 2016 Source: Dendrochronologia Author(s): Ernst van der Maaten, Marieke van der Maaten-Theunissen, Marko Smiljanić, Sergio Rossi, Sonia Simard, Martin Wilmking, Annie Deslauriers, Patrick Fonti, Georg von Arx, Olivier Bouriaud Dendrometers are measurement devices proven to be useful to analyze tree water relations and growth responses in relation to environmental variability. To analyze dendrometer data, two analytical methods prevail: (1) daily approaches that calculate or extract single values per day, and (2) stem-cycle approaches that separate high-resolution dendrometer records into distinct phases of contraction, expansion and stem-radius increment. Especially the stem-cycle approach requires complex algorithms to disentangle cyclic phases. Here, we present a new R package, named dendrometeR, that facilitates the analysis of dendrometer data using both analytical methods. By making the package freely available, we make a first step towards comparable and reproducible methods to analyze dendrometer data. The package contains customizable functions to prepare, verify, process and plot dendrometer series, as well as functions that facilitate the analysis of dendrometer data (i.e. daily statistics or extracted phases) in relation to environmental data. The functionality of dendrometeR is illustrated in this note.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Dinesh R. Bhuju

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Teodoro Carlón Allende, Manuel E. Mendoza, Diego R. Pérez-Salicrup, José Villanueva-Díaz, Antonio Lara Understanding the effects of climate on the growth of trees is important to project the response of forests to climate change. Dendrochronological analysis offers a “proxy” source for the effects of climatic variation on tree growth at different spatial and temporal scales. To examine influences of temperature and precipitation on radial growth of Pinus pseudostrobus and Abies religiosa , this study combines measurements of radial growth patterns of forest trees in the Monarch Butterfly Biosphere Reserve (MBBR) in central Mexico with temperature and precipitation variables from instrumental records. Dendrochronological samples were collected as cross sections and increment cores by using a chainsaw and increment borers, respectively. Total ring-width chronologies were developed for each site. Principal component analyses (PCA) were used to identify common temperature, precipitation and tree growth variation patterns. Correlation and response function analyses between chronologies and records of temperature and precipitation were used to evaluate the relation of climate variables on tree growth. The months during which tree growth was most strongly affected by precipitation were January, February and October from the previous year; only the temperature of September from the previous year affected the tree growth. In some chronologies, May’s average monthly maximum temperature was negatively correlated with tree growth. PCA and a comparison of PCA factor scores of climatic variables and chronologies showed no significant differences between northern, central or southern portions of the MBBR. Apparently, tree growth in the MBBR is reduced in years of low January–May precipitation combined with high summer (September of the previous year) temperatures, a scenario which is likely to occur as a consequence of global climate change.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Emma Watson, Brian H. Luckman 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.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Peter W. Brewer, Christopher H. Guiterman A wide variety of information or ‘metadata’ is required when undertaking dendrochronological sampling. Traditionally, researchers record observations and measurements on field notebooks and/or paper recording forms, and use digital cameras and hand-held GPS devices to capture images and record locations. In the lab, field notes are often manually entered into spreadsheets or personal databases, which are then sometimes linked to images and GPS waypoints. This process is both time consuming and prone to human and instrument error. Specialised hardware technology exists to marry these data sources, but costs can be prohibitive for small scale operations (>$2000 USD). Such systems often include proprietary software that is tailored to very specific needs and might require a high level of expertise to use. We report on the successful testing and deployment of a dendrochronological field data collection system utilising affordable off-the-shelf devices ($100–300 USD). The method builds upon established open source software that has been widely used in developing countries for public health projects as well as to assist in disaster recovery operations. It includes customisable forms for digital data entry in the field, and a marrying of accurate GPS location with geotagged photographs (with possible extensions to other measuring devices via Bluetooth) into structured data fields that are easy to learn and operate. Digital data collection is less prone to human error and efficiently captures a range of important metadata. In our experience, the hardware proved field worthy in terms of size, ruggedness, and dependability (e.g., battery life). The system integrates directly with the Tellervo software to both create forms and populate the database, providing end users with the ability to tailor the solution to their particular field data collection needs.

Description: Publication date: Available online 22 April 2016 Source: Dendrochronologia Author(s): Deepak K. Kharal, Udya K. Thapa, Scott St. George, Henrik Meilby, Santosh Rayamajhi, Dinesh R. Bhuju Elevation is a strong determinant of local climate and may therefore be an important factor to consider when examining the association between climate and tree growth. In this study, we developed a set of tree-ring width records for Abies spectablis (D.Don Spach) in the Manang Valley of central Nepal Himalaya and tested how tree growth and the relationship between tree growth and climate varied across a 450-m elevation transect. The sampled trees had a median age of 115 years, and the oldest individual specimen, which was located at 3775 m, had more than 212 rings. The common signal shared across the tree-ring series was relatively weak, which is typical for ring-width chronologies from the Himalayas. Even though these forests are located within a semi-arid climate, temperature had a stronger and more consistent influence on Abies growth than precipitation. All three chronologies across the transect exhibited a negative relationship with mean March–June temperatures, which could reflect the impact of warm weather during the early part of the growing season, possibly mediated through its influence on evapotranspiration and soil moisture. While interannual fluctuations in tree growth were synchronous across sites, longer-term trends in growth varied across the transect, with high-elevation trees showing elevated growth during the last two or three decades and lower-elevation trees behaving just the opposite. These disparate trends suggest the factors that control longer-term trends in forest productivity vary substantially with elevation. For studies intending to use tree-ring width records in the Trans Himalaya as climate proxies, it may be preferable to collect specimens at lower forest sites, where the agreement across the population of trees is stronger. Because longer-term trends in ring width can differ substantially from one elevation to another in this region, it may also be necessary to collect a greater number of samples from several positions along an elevation gradient.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Pepa Vasileva, Momchil Panayotov Bosnian pine ( Pinus heldreichii Christ, also known as Pinus leucodermis Antoine) is a relict species found in isolated locations in the mountains of the Balkan Peninsula and Southern Italy. The forests are of high conservational value because they are extremely rich in rare and endemic species of plants and fungi. Yet, the natural history and disturbance regime of P . heldreichii ecosystems is not well understood. Fire traces show that fires played a major role, but there is very limited historical data. Therefore proxy methods to reconstruct past events have to be used. The analysis of tree rings provides such an opportunity. To our knowledge, there have been no attempts to use tree ring cores from P . heldreichii trees to date fire events. Our aim was therefore to test if tree ring cores collected with an increment borer could successfully be used to date fires and verify other tree ring indicators caused by the fire events. We tested an approach that was based on extracting multiple cores from fire-scarred trees and nearby standing trees without injuries. A total of 136 cores from 99 trees were collected from which we dated all 34 cores with fire scars. We found the exact fire years for 29 of the samples, and the remaining 5 samples were approximately dated. Up to 83% of all sampled trees had additional growth reactions, mostly suppressions lasting 5–10 years after the fire years.

Description: Publication date: Available online 20 May 2016 Source: Dendrochronologia Author(s): Yingjun Li, Shangyi Wang, Junjie Niu, Keyan Fang, Yang Chao, Xiaolan Li, Yuhan Li We developed a tree-ring chronology based on 52 ring-width series from 25 Pinus tabulaeformis trees at Tianlong Mountain (TLM) using the signal–free method. TLM is located in the middle reaches of the Fen River, North China, and is influenced by the East Asian monsoon system. Tree growth was highly correlated (0.789) with the Palmer Drought Severity Index (PDSI) from May to July and indicated a drought-stress growth pattern. Therefore, we developed a robust May-July PDSI reconstruction for 1792-2011 that explained 62.3% of the instrumental variance for 1951-2005. Severe drought years determined by the reconstruction are consistent with conditions reported in historical documents. The TLM PDSI reconstruction was consistent with other tree-ring-based hydroclimate reconstructions in North China; thus, it may accurately represent dry/wet changes that occur over a large area. Cyclical spectral peaks at 2-8 years in the reconstructed PDSI may indicate ENSO activity, as suggested by the positive correlation with the western Pacific sea-surface temperatures (SSTs) and the negative correlation with the eastern Pacific SSTs on the inter-annual scale.

Description: Publication date: Available online 1 June 2016 Source: Dendrochronologia Author(s): Andrew M. Lorrey, Tom H. Brookman, Michael N. Evans, Nicolas C. Fauchereau, Cate Macinnis-Ng, Margaret M. Barbour, Alison Criscitiello, Greg Eischeid, Anthony M. Fowler, Travis W. Horton, Daniel P. Schrag One of the longest Southern Hemisphere tree ring chronologies that has potential to provide past climate reconstructions has been produced using New Zealand kauri ( Agathis australis ). Work to date on kauri has been limited to reconstructions from whole-ring width analysis. In this study, we present the first replicated stable oxygen isotopic composition of early season alpha-cellulose from calendar-dated kauri tree rings within the natural growth range of the species. We also use newly established kauri physiology information about stomatal conductance and a mechanistic model to place initial interpretations on kauri δ 18 O signatures. Kauri early season δ 18 O has a range from 26 to 34‰ (V-SMOW) for a site located at Lower Huia Dam in west Auckland, and the mean δ 18 O chronology from that site is significantly correlated (p 〈 0.05) to October-December vapor pressure, May-December relative humidity and other associated hydroclimatic variables. The observed statistical relationships are consistent with mechanistic δ 18 O simulations using the forward model of Barbour et al. (2004) that incorporates a leaf temperature energy balance model to calculate transpiration as forced with local meteorological variables and a range of physiological parameters. The correlation results and mechanistic model simulations suggest kauri δ 18 O early season wood has the potential to provide new quantitative past climate information for northern New Zealand, and also complement whole ring-width reconstructions of past regional climate variability – a component of which is previously established as sensitive to El Niño-Southern Oscillation activity. Additional work is required to determine whether the observed relationships are consistent across the growth range of kauri and what the optimum sample depth is before long isotope-based palaeoclimate reconstructions from modern and sub-fossil kauri sites are undertaken.

Description: Publication date: Available online 6 June 2016 Source: Dendrochronologia Author(s): Justine Ngoma, James H. Speer, Royd Vinya, Bart Kruijt, Eddy Moors, Rik Leemans Climate has been demonstrated to change at different scales for as far back as we have been able to reconstruct it. However, anthropogenic factors have accelerated and are predicted to cause significant changes in temperature and precipitation around the globe. As a consequence, vegetation is being affected. To understand the historical behaviour of individual tree species and have insight on the potential effects of climate change, tree-ring studies have been applied. In this study, we examined a genus new to dendrochronology, namely Baikiaea plurijuga (Spreng.) Harm that dominates the Zambezi teak forests in Zambia with the objective of determining whether B. plurijuga forms annual rings and if so, whether these rings are cross-datable. We further determined the relationship between ring-width of B. plurijuga and climatic variables with the aim of understanding the potential climate change effects on the growth of these species in Zambia. We collected tree-ring samples from three Zambezi Teak forest reserves: Zambezi, Ila, and Masese located in Kabompo, Namwala, and Sesheke study sites respectively. Our examination of wood anatomical structures reviewed that the wood of B. plurijuga is diffuse porous and forms annual rings which were confirmed with samples of known age. The analysis resulted in three strong tree-ring chronologies of B. plurijuga. These chronologies were correlated with climate data from local weather stations which correlated negatively with evaporation and temperature and positively with rainfall. Our regression analysis indicated that evaporation has the highest influence on tree growth at all the study sites compared to temperature and rainfall alone. Evaporation in November and March, for example, explained almost a third of the radii’s variance at the Namwala and Sesheke sites. The likely future temperature increase and rainfall decrease that are projected by IPCC for Southern Africa are likely to adversely affect B. plurijuga in Zambia.

Description: Publication date: Available online 11 June 2016 Source: Dendrochronologia Author(s): Aline Canetti, Patrícia Póvoa de Mattos, Evaldo Muñoz Braz, Pollyni Ricken, Sylvio Pellico Netto The understanding of tree growth pattern under competition in natural forests is important to support strategies and actions of forest management. The objective of this study was to evaluate the retrospective growth and competition among trees of Araucaria forest remnants in south Brazil. Dendrochronology was applied to recover growth information of Podocarpus lambertii Klotzsch ex Endl. from different strata. Rouvenien and Kuuluvainen 2 was the selected index to analyze retrospective competition between trees. It was possible to adjust an equation relating competition and diameter increments. Trees that had reached the forest upper canopy were less subject to competition in the last 30 years and probably throughout their lives. Competition variation of trees from lower strata is much larger, showing greater growth fluctuation in trees that fought for light during their lifetime. We tested this procedure on P. lambertii from Araucaria Forest, but we believe that it will be also useful to analyze growth and competition interactions among other species. Modeling individual trees’ growth with such competition analysis tools will enable the improvement of silvicultural treatments for natural forests management under specific criteria.

Description: Publication date: Available online 20 September 2016 Source: Dendrochronologia Author(s): Liang Jiao, Yuan Jiang, Mingchang Wang, Xinyu Kang, Wentao Zhang, Lingnan Zhang, Shoudong Zhao Tree growth is largely driven by climate conditions in arid and alpine areas. A strong change in climate from warm-dry to warm-wet has already been observed in northwest China. However, little is known about the impacts of regional climate variability on the radial growth of trees along elevations of the eastern Tianshan Mountains. Consequently, we developed three tree-ring width chronologies of Schrenk spruce ( Picea schrenkiana Fisch. et Mey.) ranging in elevation from 2159 to 2552 m above sea level (a.s.l.), which play an important role in the forestry ecosystem, agriculture, and local economy of Central Asia. In our study, the correlation analyses of growth-drought using the monthly standardized precipitation-evapotranspiration index (SPEI) at different temporal scales demonstrated that drought in growing season was the main factor limiting tree growth, regardless of elevation. The relationships between radial growth of Schrenk spruce and main climate factors were relatively stable by moving correlation function, and the trend of STD chronologies and basal area increment (BAI) also showed a synchronous decline across the three elevations in recent decades. And meanwhile, slight differences in responses to climate change in radial growth along elevations were examined. The drought stress increased as elevations decreased. Radial growth at the higher elevation depended on moisture availability due to high temperature, as indicated by the significant negative correlation with mean temperature in the late growing season of the previous year (August-September, p 〈 0.001). However, radial growth at the lower elevation were restricted by drought stress due to less precipitation and higher temperatures, as demonstrated by the significant negative correlation with mean temperature but positive with total precipitation in the early growing season of the current year (April-May, p 〈 0.05). In addition, the decline of radial growth (BAI) at the higher elevation (3.710 cm 2 yr −1 /decade, p 〈 0.001) was faster than that of the middle elevation (2.344 cm 2 yr −1 /decade, p 〈 0.001) and the lower elevation (3.005 cm 2 yr −1 /decade, p 〈 0.001) since 2000, indicating that the trees at higher elevation of a relatively humid environment were more susceptible to the effects of climate change due to their poor adaptability to water deficit. Therefore, the forest ecosystems would be suppressed as a result of increasing drought stress in the future, especially in the high-elevation forests of arid and semi-arid areas.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Takayuki Okochi This paper discusses a dendrochronological approach to studying works of art associated with Shintoism, an indigenous religion of Japan. Chronological studies of Shinto artwork are, by comparison, lagging behind the studies on artwork associated with the other primary religion of Japan, Buddhism. This author believes that a scientific approach, such as dendrochronology, could play an effective part in narrowing this gap. In this experiment, we conducted a series of nondestructive imaging of wooden Shinto sculptures, utilizing a micro-focus X-ray Computed Tomography (CT) system, and performed tree-ring width measurements using digital image measurement software to obtain dendrochronological information. In terms of scanning operations, one of two methods was used according to the size of the object under review. The larger object, a statue of a guardian lion-dog ( Komainu ), was dendrochronologically dated to 1581, and the smaller deity statues were dated 1178. The dendrochronological data gained through this experiment will be an extremely valuable resource for future studies on Shinto artwork in Japan.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Francis Munalula, Melanie Blumentritt, Thomas Seifert, C. Brand Wessels The objectives of this study were to develop and assess a method of using tree ring measurements in standing pruned Pinus patula trees for modelling the knotty core of the pruned section of a tree and to assess variability in knotty core diameters in the tree stem. A total of 170 trees from 17 compartments on a wide variety of growth sites from the Mpumalanga escarpment in South Africa were selected and destructively sampled. We show that ring width measurements at breast height can be used to predict growth in the upper pruned section which in turn can be used to reconstruct the internal knotty core through the full pruned section of the log. Analysis of variation for the entire data set from ring width measurements showed that there was far greater variation in knotty core percentages (the percentage of diameter occupied by knotty core) between different compartments than within compartments. Within a tree, the knotty core percentages between three stem sections, 0.0–2.4 m, 2.4–4.8 m, and 4.8–7 m, differed significantly. As expected the knotty core percentages were found to increase from the bottom section (49.1%) to the top section (65.4%). A comparison of the actual measured knotty core size and the modeled knotty core size of a sub-sample of trees showed only a modest relationship ( R 2 = 0.62). Reasons for this might be variability in pruning quality, inaccurate pruning records, nodal swellings, and the methodology used to measure the actual knotty core sizes. Knowledge of knotty core sizes can be used as a decision aid in the forest and forest products industry.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Mirela Tulik, Szymon Bijak Oak decline, a complex process leading to increased mortality of this species, has been observed in Europe for many years. Previous studies suggest that climate conditions, especially drought, may be one of the most important factors that trigger this phenomenon. The paper investigates the radial growth and wood anatomy features of pedunculate oak ( Quercus robur ) trees of various health status as well as their response to climate conditions. Wood samples including all annual increments were taken at two sites (western and central Poland, 15 trees each). Based on the crown defoliation level, three health groups (healthy, weakened and dead oaks) were distinguished. Cross-sections were prepared with sliding microtome and Cell P image analysis software was used for the measurements. Tree-ring width (TRW), earlywood vessels density (VDen) and non-weighted vessels diameter (VD) were determined and correlated with mean monthly values of temperature, precipitation, vapour pressure, and Palmer Drought Severity Index (PDSI). Radial increment and anatomical parameters were significantly higher for the healthy oaks than for the weakened and the dead trees. TRW showed smaller dependence on climate than analysed anatomical attributes. No obvious pattern of relationship was found between oak radial growth and climate regarding tree health status. Our results revealed that the drought has a weak impact on the process of oak decline on investigated sites in Poland.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Nina M. Datsenko, Dmitry M. Sonechkin, Ulf Büntgen, Bao Yang In order to characterize the main growth modes of high-elevation conifers, such as typical variations inherent to annual tree growth records, we resolved eigen problems related to intra-record correlation coefficient matrices of several large sample sets for (A) very long-lived Chinese junipers and (B) shorter-lived European pines and larches. Such modes allow for the identification of tree growth variations of different origins, i.e., resulting from climate and/or microenvironments as well as origins that are purely biological in nature. We determined that these modes are universal, namely, that they are identical for both ring width (RW) and maximum latewood density (MXD) records. Certain specific shapes found in these main modes were indicative of anomalous tree growth. Cross-correlations between identical modes related to RW and MXD data were determined to be nonessential. This suggests that RW and MXD data likely represent different aspects of tree growth response to varying climatic and environmental conditions.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Dominika Wrońska-Wałach, Mateusz Sobucki, Agata Buchwał, Elżbieta Gorczyca, Joanna Korpak, Piotr Wałdykowski, Holger Gärtner Missing and wedging rings are common features of tree growth. They occur more frequently in roots than in stems and were reported for various species and sites. These rather frequent irregularities in roots make dendrochronological analysis and cross-dating of roots more challenging. The goal of this study was to present a compiled method for a quantitative analysis of ring-growth irregularities. The analysis was conducted on ten spruce ( Picea abies L. Karst) roots taken from the Gorce Mountains (Southern Poland). A four-step cross-dating of these root samples was applied. Three to six cross-sections were analysed within each root and cross-dated with a corresponding stem and site chronology. All ring-growth analyses were conducted on micro sections. Finally, the dating method was evaluated using three control indicators. The study revealed that wedging rings occurring in both, cross-sectional and longitudinal profiles were observed in 17.3% of the rings analysed. The application of a combined zig-zag segment tracing and serial sectioning allowed to significantly reduce, compared to previous methods, the amount of undetected missing rings and revealed them as cross-sectional or longitudinal wedging rings. Thanks to the application of control indicators the irregularities occurring in rings of roots were quantified and compared with different environmental factors such as droughts, air pollution, insect outbreaks and geomorphological processes. Significant positive correlation between root age and the number of radial growth irregularities in roots was demonstrated. A detailed investigation of multiple cross-sections per root enabled to trace all types of ring irregularities in the roots and substantially reduced cross-dating subjectivity.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): A. Costa, I. Barbosa, C. Roussado, J. Graça, H. Spiecker In the Mediterranean climate regions, drought events are expected to affect the growth of forests ecosystems by changing trees growth rates and eventually inducing shifts in their growth patterns. Cork oak ( Quercus suber L.) is a strictly western Mediterranean tree species periodically harvested for its bark, the cork. So far, cork oak has received limited attention for dendroclimatological studies due to its typical faint and erratic tree wood rings. Moreover, its distinct cork rings chronologies have been completely neglected. In this study we introduce an approach using cork ring chronologies dated back 9–10 years for climate response. Despite enhancing interannual variability and increasing statistical response to short-term climatic variability, still poorly understood, this study will possibly allow infer long-term climate response. We analyzed the cork ring chronologies of 55 cork samples collected in mature (under exploitation) trees in three distinct locations in southwestern Portugal. Cork growth recorded a high climate signal, with highly significant and coherent responses to the yearly climate-related sources of variation. We successfully assessed trends of cork growth via correlation analysis including selected climate variables among mean monthly temperature, monthly precipitation and, on an annual basis, eight precipitation indices. The high mean sensitivities and inter-series correlations found for cork ring chronologies combined with the significant variance explained by climate variables suggest that climate is likely one dominant signal that affects cork growth, but local environmental stresses can decisively affect this (climate) signal. Assuming cork growth as a proxy for cork oak growth, it seems conceivable that despite the trees being highly resistant to drought stress, cork oak woodlands in southwestern Portugal would have to face lesser growth in a global warming scenario.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Fabio Natalini, Reyes Alejano, Javier Vázquez-Piqué, Isabel Cañellas, Guillermo Gea-Izquierdo Forest decline and increasing tree mortality are of global concern and the identification of the causes is necessary to develop preventive measures. Global warming is an emerging factor responsible for the increasing tree mortality in drought-prone ecosystems. In the southwestern Iberian Peninsula, Mediterranean holm oak open woodlands currently undergo large-scale population-level tree die-off. In this region, temperature and aridity have increased during recent decades, but the possible role of climate change in the current oak mortality has not been investigated. To assess the role of climate change in oak die-off in managed open woodlands in southwestern Spain, we analyzed climate change-related signals in century-long tree ring chronologies of dead holm oaks. We examined the high/low-frequency variability in growth and the relationship between growth and climate. Similar to other Mediterranean forests, growth was favored by precipitation from autumn of the year prior to ring formation to spring of the year of ring formation, whereas high temperatures during spring limited growth. Since the 1970s, the intensity of the high-frequency response to water availability increased simultaneously with temperature and aridity. The growth trends matched those of climatic changes. Growth suppressions occurred during droughts in the 1970s, 1980s and 1990s. Widespread stand-level, age-independent mortality occurred since 2005 and affected trees that cannot be considered old for the species standards. The close relationship between growth and climate indicate that climate change strongly controlled the growth patterns. This suggests that harsher climatic conditions, especially increased aridity, affected the tree performance and could have played a significant role in the mortality process. Climate change may have exacerbated or predisposed trees to the impact of other factors (e.g. intense management and pathogens). These observations could suggest a similar future increase in oak mortality which may occur in more northern oak open woodlands if aridity further increases.

Description: Publication date: Available online 2 April 2016 Source: Dendrochronologia Author(s): Michal Bosela, Patrizia Gasparini, Lucio Di Cosmo, Barbara Parisse, Flora De Natale, Stanislao Esposito, Ľubomír Scheer European National Forest Inventories (NFIs) are well established in most of the European countries. In some NFIs, core samples are taken to estimate volume increments at annual resolution. However, the potential of the NFI for dendroecological investigations has not been evaluated so far. Therefore, the aim of this study was to test the potential of dendrochronological data collected during the Italian NFI in 2006. Silver fir was selected as a test species. Core samples were taken from eighty-one trees including one sample per inventory plot (IP). The 81 IPs were distributed across the Italian Alps and the northern Apennine thus well representing the site conditions of the study area. The effects of the detrending method and sample size on detecting middle- to long-term growth trends and high-frequency climate signals were tested. Further, cluster analysis was applied to find dissimilarities among tree-ring width (TRW) series. Results suggest the detrending method to be the most important factor for detecting growth trends, but not for identification of high-frequency climate signals. Samples size essentially influences the final mean chronology, but it does not bring new information when larger than 30 series. Two groups of trees were recognised with distinct middle-term TRW patterns, although being the same in terms of climate sensitivity. Results are mostly in line with recent findings of other authors, which suggest the potential of the NFI data for dendroecological investigations.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Elena A. Babushkina, Eugene A. Vaganov, Alexi M. Grachev, Nataliay V. Oreshkova, Liliana V. Belokopytova, Tatiana V. Kostyakova, Konstantin V. Krutovsky The genetic mechanisms underlying the relationship of individual heterozygosity (IndHet) with heterosis and homeostasis are not fully understood. Such an understanding, however, would have enormous value as it could be used to identify trees better adapted to environmental stress. Dendrochronology data, in particular the individual average radial increment growth of wood measured as the average tree ring width (AvTRW) and the variance of tree ring width (VarTRW) were used as proxies for heterosis (growth rate measured as AvTRW) and homeostasis (stability of the radial growth of individual trees measured as VarTRW), respectively. These traits were then used to test the hypothesis that IndHet can be used to predict heterosis and homeostasis of individual trees. Wood core and needle samples were collected from 100 trees of Siberian larch ( Larix sibirica Ledeb.) across two populations located in Eastern Siberia. DNA samples were obtained from the needles of each individual tree and genotyped for eight highly polymorphic microsatellite loci. Then mean IndHet calculated based on the genotypes of eight loci for each tree was correlated with the statistical characteristics of the measured radial growth (AvTRW and VarTRW) and the individual standardized chronologies. The analysis did not reveal significant relationships between the studied parameters. In order to account for the strong dependence of the radial growth on tree age the age curves were examined. An original approach was employed to sort trees into groups based on the distance between these age curves. No relationship was found between these groups and the groups formed based on heterozygosity. However, further work with more genetic markers and increased sample sizes is needed to test this novel approach for estimating heterosis and homeostasis.

Description: Publication date: June 2016 Source: Dendrochronologia, Volume 38 Author(s): Songlin Shi, Zongshan Li, Hao Wang, Xing Wu, Shuai Wang, Xiaochun Wang, Guohua Liu, Bojie Fu Although recent studies have demonstrated that annual growth rings are present among perennial forbs species at high northern latitudes, little is known about whether there are demarcated growth rings of perennial forbs in the Loess Plateau of China where plant growth is strongly limited by dry climate conditions and severe soil erosion. In this study, we collected the main roots of 11 perennial forbs species along the precipitation gradient in the Loess Plateau, and analyzed the growth rings in the secondary root xylem. We found that ten species showed distinct annual growth rings, and the anatomical patterns, including vessel size and density, varied considerably among different families. Our results suggest, for forbs species in the Loess Plateau, that vessel diameter in the root xylem was strongly correlated with growth rate of the forb’s roots. Ring widths of the forbs showed a significant declining trend, reflecting the deteriorating signal of growth condition with age. In comparison to other families, forb species of Fabaceae usually have the evidently larger vessels that link directly to higher hydraulic capacity and growth rate. In terms of annual ring width patterns, this study provides an applicable approach to detecting effects of limited climatic conditions and life history strategies on herbaceous vegetation in the Loess Plateau.

Description: Publication date: Available online 9 March 2016 Source: Dendrochronologia Author(s): Narayan Prasad Gaire, Madan Koirala, Dinesh Raj Bhuju, Marco Carrer Alpine treelines act as bio-indicators and bio-monitors of environmental change impacts in high elevation forests. This dendro-ecological study carried out in treeline ecotones in the Sagarmatha (Mt. Everest) National Park (SNP), eastern Nepal Himalaya, aimed to assess treeline dynamics and to understand the response of treeline forming Abies spectabilis (D. Don, Mirb) and Betula utilis (D. Don) to environmental change. At three treeline sites we placed two to four belt transects (size: 20 m wide, variable length) which bisected the treeline as well as the tree species limit. The results revealed spatio-temporally heterogeneous regeneration with a higher regeneration of A. spectabilis compared to B. utilis . Warm temperatures during summer (JJA) growing seasons combined with sufficient moisture favored the growth of A. spectabilis while moisture stress during spring seasons (MAM) mainly limited the growth of B. utilis . The regeneration of A. spectabilis was favored by high temperatures throughout the year with sufficient moisture. The climatic response of the regeneration of B. utilis was spatiotemporally different and variable. Results predict a changing community structure in the treeline in response to future environmental change. During the past 200 years, A. spectabilis shifted upward by about 0.93 m/yr and B. utilis by 0.42 m/yr, with stabilization during the second half of the 20th century at the majority of the sites. The recent stability in treeline position of both species at most sites indicated that in addition to favorable climate, species-specific competitive abilities during the recruitment phase, recruitment suppression in the Krummholz and dwarf scrub belts, and grazing determine regeneration success and treeline position in the region.

Description: Publication date: Available online 19 March 2016 Source: Dendrochronologia Author(s): Alexander V. Kirdyanov, Olga N. Solomina, Eugene A. Vaganov, Ulf Büntgen

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Hanxue Liang, Lixin Lyu, Muhammad Wahab Long-term summer temperature records are important for climate studies on the Tibetan Plateau (TP). Here, we used tree-ring maximum latewood density (MXD) to develop a well-replicated regional chronology back to the year 1630 for the southeastern TP. The MXD chronology is positively related to the observed August mean minimum temperatures (AMMT) in the period 1961–2011. Therefore, the AMMT was reconstructed from the MXD chronology. The reconstruction explained 42.6% of the total variance in the observed AMMT. During the past 382 years, warm periods were found during 1646–1694, 1770–1805, 1930–1971 and 1992–2011, and cold periods were found during 1630–1645, 1695–1749, 1806–1825, 1889–1929 and 1972–1991. Extreme cold summers (≤mean − 2 SD) occurred in the years 1701, 1777, 1810, 1817, 1835, 1843, 1857, 1871, 1911, 1914, 1915, 1939, 1983 and 1984, whereas the warm summers (≥mean + 2 SD) occurred in the years 1786, 1788, 2003, 2004 and 2005. A comparison with temperature records in surrounding regions showed general agreements, indicating the fidelity of our reconstruction and its ability to represent summer temperature variations over a broad geographic extent. Conspicuous in-phase relationships between our reconstruction and the Atlantic Multidecadal Oscillation (AMO) indicated a strongly positive association between large-scale climate circulations and summer temperature variability on the southeastern TP at multidecadal scales.

Description: Publication date: Available online 25 March 2016 Source: Dendrochronologia Author(s): Magdalena Opała, Tadeusz Niedźwiedź, Oimahmad Rahmonov, Piotr Owczarek, Łukasz Małarzewski Millennial long tree-ring records are crucial for better understanding temperature and hydroclimatic variability over the globe. Juniper is one of particularly long-lived species, which can provide more than a thousand-year record, especially in Central Asia. However, there is a lack of dendrochronological series from the Pamir Mountains. Here we report the first 1010-year (AD 1005–2014) juniper tree-ring chronology from the mountain ranges of north-western Tajikistan, the western Pamir-Alay. We present the potential of Juniperus semiglobosa and Juniperus seravshanica in developing millennia-long records. We sampled three study sites at the elevations from 2200 to 3500 m. In general, the climate-growth analyses show that radial growth of the Himalayan pencil juniper is positively correlated with the winter precipitation and spring temperature. At some sites tree rings were also positively correlated with summer temperature. Our findings demonstrate the importance of developing the tree-ring data network for the Pamir-Alay and its potential for reconstruction of hydroclimatic variability over the last thousand years in this region.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): I. Panyushkina

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Amanda B. Young, David A. Watts, Alan H. Taylor, Eric Post We examined the suitability of two deciduous arctic shrubs ( Salix glauca L. and Betula nana L., hereafter Salix and Betula , respectively) for dendroclimatological analysis at two sites in West Greenland. Chronologies were successfully cross-dated, and the oldest covered the period 1954–2010 (Expressed Population Signal [EPS] > 0.85, 1977–2010). Distinctive pointer years, also called micro-rings, including those from a known outbreak of the irruptive moth Eurois occulta L. (Lepidoptera: Noctuidae) that peaked in 2005, assisted in the dating process. Climate-growth analyses were performed in two ways: first, using correlation analysis between residual site-level chronologies and monthly and seasonal climate data, and second, using linear mixed effects models (LMM) with seasonal climate data and standardized chronologies for each individual. We used climate data for the current and previous years for a given growth ring for both analyses. Both analyses revealed differences in climate-growth response among species and among sites of contrasting topography. Salix ring widths from south facing slopes correlated positively with current year’s summer temperatures, while those on gentle slopes associated negatively with current year’s spring precipitation. Betula was only sampled at one site (flat), and displayed associations with temperature and precipitation in spring. Results from the LMM largely corroborated the correlations for Betula and Salix on south facing slopes. Salix at the flat site displayed significant associations with a large number of climate variables, most strongly previous year’s summer and autumn temperatures, though precipitation in multiple seasons of the current and prior year did a better job of accounting for the variation in the data. Many dendrochronological studies in the Arctic illustrate clear summer temperature responses, but the majority were conducted on a single topographic position. Due to the heterogeneity of West Greenland’s landscapes, it is important to examine individuals from varying topographies. We found that samples collected from south facing slopes do appear to respond positively to summer temperatures, while those on shallow slopes respond to a wider array of seasonal temperature and precipitation parameters. Accounting for these species and topographic differences, when sampling, is imperative for improving our understanding of how plant communities in the Arctic will respond to ongoing and expected warming.

Description: Publication date: March 2016 Source: Dendrochronologia, Volume 37 Author(s): Coralie Mathaux, Jean-Paul Mandin, Christine Oberlin, Jean-Louis Edouard, Thierry Gauquelin, Frédéric Guibal Juniperus phoenicea is a tree that can grow on vertical cliff faces in dry and warm Mediterranean climate conditions. These trees are adapted to extreme growing conditions where the main constraints are verticality, compact hard limestone, and low water supply. They respond to these constraints via various specific features and high longevity. The objective of this study is to confirm whether or not their tree-rings are annual in order to specify growth strategies and accurately date these trees. Trunk morphology, anatomical wood anomalies and radial growth were analyzed on 53 trees in the Ardèche canyon. Crossdating of the ring widths using traditional dendrochronological techniques was unsuccessful, so radiocarbon dating of tree pith was used to assess tree age, and wiggle-match dating was used to test for differences between number of rings counted and radiocarbon dates. Radiocarbon dates span the period 2520–685 BP. Minimal difference between radiocarbon dates and ring counts was apparently small—missing rings occur, but not in large numbers. Tree-ring formation is annual and radial growth is low, which creates stunted old trees. Such old living trees are uncommon in the Mediterranean basin, especially at low elevation. They can provide long tree-ring chronologies back to 792–524 cal BC. Results from the radiocarbon dating indicate that accurate annual dating of these rings may be possible by crossdating. J. phoenicea growing on cliffs offer a valuable model to better understand cliff population ecology and the functional responses of trees that can live in harsh environmental conditions.

Description: Publication date: Available online 19 November 2016 Source: Dendrochronologia Author(s): Alejandro Venegas-González, Pedro H.S. Brancalion, Alci Albiero, Matheus Peres Chagas, Claudio R. Anholetto, Gilles Chaix, Mario Tomazello Filho In tropical forest, landscape fragmentation and the consequent degradation of disturbed forests increase the incidence of light and dry hot winds, causing a disturbance on natural regeneration. Under these conditions, lianas (woody vines) development is stimulated instead of other species, which are more suited to mature forest and under less influence of the edge effect. For this, lianas colonization is an important variable for assessing the disturbance level of a forest. In this context, it becomes important to understand the nature of the competitive relationships between hyper-abundant lianas and ring growth of the host trees. Here, we selected trees with occupation or absence of lianas from two tropical species − Pinus caribaea var. hondurensis (Caribbean pine) and Tectona grandis (teak) − localized in a semideciduous forest fragment in southeastern Brazil, aiming to compare growth, climatic response, anatomy (vessels and intra-annual density fluctuations), wood density and carbon, by tree-ring analysis. The results showed that the lianas caused a change in tree-ring anatomy of host trees in last 10 years, mainly. We observed that trees occupied by lianas had a decrease the radial growth and carbon in the two species, an increase of the vessels size in teak and a decrease of the IADF frequency in Caribbean pine. In teak, the climate-tree relationship indicated that trees with lianas had lower response to rainfall and higher response to temperature in the summer (rainy and hottest period); in Caribbean pine, we observed that trees with lianas had a 2-month delay in the radial growth response to rainfall in the dry season. In the teak group, we observed that host trees had higher wood density values than liana-free tree in the outer rings, and the opposite was showed for pine. These findings show that tree-ring growth of host trees are a strong bioindicator of forest disturbance caused by aggressive colonization of lianas. We believe that these methods are applicable to future studies relating to the effects of habitat fragmentation and forest degradation on biodiversity and ecosystem services, particularly in the context of global climate change.

Description: Publication date: Available online 23 November 2016 Source: Dendrochronologia Author(s): Maegen L. Rochner, Hudson W. Kelley, Christopher S. Wilson, Tim Bennett, Henri D. Grissino-Mayer The Timothy and Lucretia (Jones) Warner Homestead is located in Brighton, Michigan. For over eight years, a descendant of the Warner family has been excavating the site and restoring the Greek Revival house located on the property. Although already listed on the National Register of Historic Places (NRHP), a dendrochronological study of the property provides independent scientific evidence to verify the dating of the house and present a possible construction timeline for the homestead. A total of 13 timber samples, 10 from the Warner House and three saved from a previously destroyed barn, were sent to us for dendrochronological dating. Eight of the samples, six from the house and two from the barn, crossdated statistically with each other and were used to build a floating 181- year tree-ring chronology. Using a white oak ( Quercus alba L.) reference chronology (Cranbrook Institute in Michigan, MI005.crn) available from the International Tree-Ring Data Bank, we absolutely dated the tree-ring chronology from the Warner House and barn to the period 1718 to 1898 (r = 0.45, n = 181 years, t = 6.74, p 〈 0.0001). The two crossdated white oak samples from the barn indicated harvest between fall 1876 and spring 1877. Five samples from the Warner House indicated tree harvesting occurred between fall 1853 and spring 1855, which corroborates the year of construction (1855) determined by documentary analysis for the NRHP. Findings also support one phase of construction for the house, rather than multiple phases, which had originally been postulated based on architectural details. One sample that dated to 1899 also suggests a later renovation with the erection of a dividing wall. The two samples from the barn post-date the construction of the house, supporting the progressive farm model that suggests that large barns were built only after a timber frame home was erected. The dates returned for the barn support the WPA Rural Property Inventory that states the barn was built around 1880. Even with relatively few samples, this study demonstrated how tree-ring dating can corroborate and elaborate on documentary evidence of construction dates of multiple structures at one historic site.

Description: Publication date: Available online 5 October 2016 Source: Dendrochronologia Author(s): Tatiana Kostyakova, Marina Bryukhanova

Description: Publication date: Available online 5 October 2016 Source: Dendrochronologia Author(s): Álvaro Camisón, Fernando Silla, J. Julio Camarero Quantifying climate-growth associations is needed to evaluate how forest productivity will respond to climate change. Year-to-year fluctuations in forest productivity and radial growth are partly explained by local climatic conditions driven by large-scale atmospheric patterns. This is illustrated by Iberian forests in the western Mediterranean Basin, which are subjected to complex climatic and atmospheric influences such as Atlantic and Mediterranean cyclogenesis. The North Atlantic Oscillation (NAO) is one of the major atmospheric circulation patterns affecting Iberian forests since positive winter NAO phases lead to dry and warm conditions. The Western Mediterranean Oscillation (WeMO) may also explain Iberian forest growth in some areas since this index captures Mediterranean cyclogenesis and WeMO negative phases are linked to warm and wet spring to summer conditions. Here, we analyze the associations between atmospheric patterns, climate and tree growth and we determine if they are changing through time. We use dendrochronology to relate radial growth of four tree species (Pyrenean oak, Sweet chestnut, Maritime pine and Scots pine) growing in western Spain to climate conditions and the NAO and WeMO indices. Winter and early spring temperatures increased since the 1950s in the area whereas the negative association between winter precipitation and the NAO strengthened since then. However, mean temperature rise was particularly evident since the 1970s. Growth was reduced by dry conditions during the growing season (spring and summer), but also by cold and dry conditions during the previous autumn and winter. This explains why the NAO January and the WeMo April indices were negative to growth of three species excluding Pyrenean oak. The early 1970s reflected an inflection point in the instability of climate-growth associations in the study area. We conclude that the winter NAO is a relevant driver of forest growth in the western Iberian Peninsula forests but additional atmospheric patterns (WeMO) also affect, albeit to a minor extent, these forests.

Description: Publication date: Available online 6 October 2016 Source: Dendrochronologia Author(s): Henri D. Grissino-Mayer, David J. Hally The King site is a Late Mississippian (ca. 1400–1540 CE) aboriginal town located in northwestern Georgia along the Coosa River associated with the Coosa Chiefdom. The site was settled ca. 1530 but was occupied for perhaps only 50 years or so based on the lack of horizontal stratigraphy. The site was visited by members of either or both the Hernando de Soto expedition in 1540 and the Tristan de Luna expedition in 1560. In 1974, archaeologists discovered and removed 36 sections of subterranean charred pine posts from six house features. Our objectives were to determine if the tree rings on these posts could be dendrochronologically dated to verify the dates of site occupation and confirm the construction sequence of several houses determined originally via stratigraphic and archaeological evidence. We were able to graphically and statistically crossmatch 13 measurement series representing 10 posts from 5 of the 6 structures, yielding a 157-year floating chronology (average interseries correlation = 0.60). We were unable to absolutely crossdate this floating chronology with the only regional reference chronology long enough (back to 1378 CE) to reach the 16th century, an eastern red cedar chronology from eastern Tennessee. Archaeological evidence indicated Houses 8 and 23.4 were built later in the King site occupancy, confirmed by the tree-ring dates as both houses have the youngest tree rings of the five structures. House 14 had the oldest outermost tree rings but archaeological evidence suggests this house also was likely constructed late in the King site occupancy. We propose some posts were salvaged and reused from abandoned houses as the King site became rapidly depopulated in the last 10–20 years of site occupancy, thus explaining the age of posts used in House 14. We urge archaeologists working in the Southeastern U.S. to consider developing a more formal process for exhuming and preserving charcoalized wood remains from archaeological sites so that these samples can be evaluated using dendrochronological techniques.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): Margarita Kisternaya, Valery Kozlov, Irina Grishina, Marina Leri Data on the quality of timber used for building chapels – small buildings for public worship, enabled determination of visual criteria used for the selection of timber in the Republic of Karelia, located in the north-western part of the Russian Federation. It was revealed that as for the majority of timber structures in the region, Scots pine ( Pinus sylvestris L.) logs were selected for the chapels. Trees perceived as 'Holy' such as spruce ( Picea abies Kr.), were not used in these worship structures, in contrast to practices in the neighboring Leningrad Region. The age of the logged trees was 100–150 years, with a high proportion of young trees. Data obtained proved convincingly that compared with huge parish churches, selection of timber for these small chapels was not so strict. Multivariate analysis of variance showed that an ethnological factor played a significant role in the selection of wood for the buildings. Mature trees with narrow tree rings were preferred for worship structures preserved in villages populated by Karelians – the Baltic-Finnic tribe living in the region since ancient times. In villages with a dominantly Russian population, young pines with wide annual rings were dominantly used. A correlation between the height of the structures and the average diameter of the logs used was found with the coefficient of determination high in Karelian villages and lower in Russian villages.

Description: Publication date: Available online 28 October 2016 Source: Dendrochronologia Author(s): Āris Jansons, Roberts Matisons, Silva Šēnhofa, Juris Katrevičs, Jānis Jansons The plasticity of climate-growth relationships of trees is one of the main factors determining the climate-induced changes in forest productivity and composition. In this study, high-frequency variation of tree-ring width (TRW) of four native and three alien tree species and two hybrids of Populus L. growing in Latvia (hemiboreal zone) was compared using a principal component analysis based on TRW indices for the period 1965–2009. The effect of climatic factors was assessed using a bootstrapped correlation analysis. Influence of common climatic factors related to the length of the vegetation season, winter temperature, and water regime in summer was traced in the TRW of the studied species and hybrids. The combination and effect of the identified factors differed by species (and hybrids), to a certain extent explaining the diversity of TRW patterns. Nevertheless, some similarities among the species were also observed, suggesting the plasticity of growth response. Scots pine was generally sensitive to winter temperatures, but Norway spruce was mainly sensitive to summer water regime, while black alder was sensitive to winter temperatures and precipitation in spring. In contrast, silver birch showed the lowest sensitivity to the tested climatic factors (demonstrating sensitivity to winter precipitation in a few sites), suggesting tolerance to weather fluctuations. The TRW of the alien species was primarily sensitive to climatic factors related to water regime in the summer of the year preceding the formation of tree-ring, implying differences in mechanisms regulating wood increment. Nevertheless, temperature in the dormant period was significant for European larch in a few sites, suggesting sensitivity to cold damage. The variation of TRW of Populus hybrids diverged from others, as their growth was negatively correlated with the temperature in autumn, spring, and summer and positively correlated with water balance. Although the annual water balance in Latvia is positive, the effect of water deficit on tree growth was apparent.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): Somaru Ram, H.P. Borgaonkar 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.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): Fabio Natalini, Reyes Alejano, Javier Vázquez-Piqué, Marta Pardos, Rafael Calama, Ulf Büntgen Climate warming and increasing aridity have impacted diverse ecosystems in the Mediterranean region since at least the 1970s. Pinus pinea L. has significant environmental and socio-economic importance for the Iberian Peninsula, so a detailed understanding of its response to climate change is necessary to predict its status under future climatic conditions. However, variability of climate and uncertainties in dendroclimatological approach complicate the understanding of forest growth dynamics. We use an ensemble approach to analyze growth-climate responses of P. pinea trees from five sites along a latitudinal gradient in Spain over time. The growth responses to April-June precipitation totals were stronger in the north than in the south. Since the 1950s, the sensitivity of growth to April-June precipitation increased in the north and decreased in the south. Meteorological drought usually started in May in the southern sites, but in June-July in the northern sites. The water deficit in the southern sites is thus greater and more limiting for tree growth, and this likely accounts for the lower growth sensitivity during these months. Our results indicate that P. pinea has a high degree of plasticity, suggesting the species will withstand changing climatic conditions. However, growth response to drought regimes varies among P. pinea populations, suggesting that different populations have different capacities for acclimation to warmer and drier climate, and this may influence future vegetation composition.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): Jernej Jevšenak, Tom Levanič Studies focused on tree ring—climate relationships usually use linear methods to find the optimal transfer function. In our study, three sites with three different tree species from the Western Balkan region were selected to compare linear and artificial neural network (ANN) nonlinear models and to see whether linear models can be potentially replaced with ANN in climate reconstruction. For each site, one linear and two different ANN models were calculated. For all analysed sites, we were able to find a better fit using the advanced technique of ANN. All calibration and verification statistics were in favour of ANN models. A climate variable was reconstructed for a selected site using linear and nonlinear ANN methods. We demonstrated that ANN is always a more effective method, which always produce better results than linear models. The key to success is a properly selected training algorithm, which prevents overfitting and is able to find the optimal transfer function, also linear, if that is the case.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): Lidio López, Ricardo Villalba Given the scarcity of instrumental climatic data in the South American tropics, it is valuable to explore the dendrochronological potential of the numerous tree species growing in the region. In this paper, we assessed for the first time the dendrochronological characteristics of Schinopsis brasiliensis , an arboreal species from the dry-tropical Cerrado and Chaco forests in Bolivia and adjacent countries. Similar to most woody species in the Cerrado and Chaco regions, growth rings of S. brasiliensis are delimited by the presence of thin but continuous lines of marginal parenchyma. Based on 22 samples from 15 trees, we present the first ring-width chronology for this species covering the period 1812–2011 (200 years). Additionally, a 106-year floating chronology from S. brasiliensis was developed using cores from four columns from the church of San Miguel, Santa Cruz, built in the period 1720–1740. Standard dendrochronological statistics indicate an important common signal in the radial growth of S. brasiliensis . The comparison of variations in regional climate and ring widths shows that tree growth is directly related to spring-summer rainfall and inversely related to temperature. Following the winter dry season, rainfall in late spring and early summer increases soil water supply, which activates tree growth. In contrast, above-average temperatures during the same period increase evapotranspiration, intensify the water deficit and reduce radial growth. The dependence of S. brasiliensis growth on water supply is evidence of its dendrochronological potential for reconstructing past precipitation variations in the extensive tropical Cerrado and Chaco forest formations in South America. Using wood from historical buildings opens the possibility of extending the chronologies of S. brasiliensis over the past 400–500 years.

Description: Publication date: Available online 13 September 2016 Source: Dendrochronologia Author(s): Feng Chen, Huaming Shang, Yujiang Yuan Cores of Schrenk spruce from seven sites of eastern Tien Shan were used to develop a regional tree-ring chronology to extend the climate record. We developed a August–July Standardized Precipitation Evapotranspiration Index (SPEI) reconstruction that spans AD 1725–2013 based on the regional tree-ring chronology. The reconstruction model accounts for 45.3% of the SPEI variance from 1959 to 2013. The SPEI reconstruction agrees reasonably well with the dry and wet periods previously estimated from tree rings in northern Xinjiang. The correlation analysis revealed that temperature plays an important role in regional drought variability, and some extreme wet years also coincide with the volcanic eruptions.

Description: Publication date: December 2016 Source: Dendrochronologia, Volume 40 Author(s): O. Prokop, T. Kolář, U. Büntgen, J. Kyncl, T. Kyncl, M. Bošeľa, M. Choma, P. Barta, M. Rybníček Although Slovakia is largely forested and rich in historical buildings, it is one of the few European countries without a millennium-long tree-ring chronology. In this study, we gather all available oak ring width data from Slovakia, establish a new composite chronology and assess its climate sensitivity. The nation-wide oak network includes 276 samples from historical buildings and 1028 modern series from material that was randomly collected at sawmills and wood submission sites across Slovakia. The final composite oak record covers the period from CE 967–2013, reflects a distinct hydroclimatic signal from late spring to early summer, and is highly correlated with other oak chronologies from surrounding countries. Although this study reveals a high degree of growth coherency and climate sensitivity inherent to the new Slovakian oak ring width chronology, changes in sample size at the transition from modern to relict material and further back in time limit any applicability to palaeoclimatic analysis.

Description: Publication date: Available online 30 November 2016 Source: Dendrochronologia Author(s): Trevis J. Matheus, Justin T. Maxwell, Joshua Oliver, Michael Thornton, Michael Hess, Grant L. Harley Spring Mill was an important pioneer village in Lawrence County, Indiana during the 19th century, with its three-story gristmill serving much of the region. Due to the historical and regional importance of Spring Mill to pioneers, the state of Indiana recreated the original village in the 1930s. While most wooden structures were recreated using donated logs from historic structures around the state, three original nearby structures were relocated to the park. The history of Spring Mill is well documented, but less is known about the three original structures, which are the oldest wooden structures in the village. We used dendroarchaeological methods to determine the construction history of the three original pioneer structures. We found the cutting dates of logs from two of the structures (Granny White and Sheeks Houses) confirmed colloquial construction dates, while the Todd House was believed to be constructed fifteen years earlier than the cutting dates suggested. We also found the preferred wood for pioneer homes was L. tulipifera, as most of the logs used in the original construction of the homes were from this species. Using dendroarchaeological methods provided a means to determine the construction history of pioneer cabins in southern Indiana and our findings suggest that these methods can be used throughout the Midwest where reference chronologies are available.

Description: Publication date: Available online 11 December 2016 Source: Dendrochronologia Author(s): Oliver Konter, Paul J. Krusic, Valerie Trouet, Jan Esper

Description: Publication date: Available online 14 December 2016 Source: Dendrochronologia Author(s): Grant L. Harley, Justin T. Maxwell, David Holt, Christopher B. Speagle The Deason House is located in the heart of the Piney Woods region in the town of Ellisville, Mississippi. During the American Civil War, the Deason House became the epicenter for an event that started a rebellion against the Confederate government. On 5 October 1863, a Confederate deserter named Newton Knight allegedly shot and killed Confederate Major Amos McLemore in the Deason House, which eventually lead to the formation of the Free State of Jones. Despite the historical importance of the house, oral accounts and written documents have failed to provide accurate construction history of the structure. We coupled techniques of dendrochronology and geophysical survey to better understand the construction history of the Deason House and cultural activities of its inhabitants. We extracted 35 Pinus palustris (Mill.) timbers along the west-facing exterior weatherboards and from various logs within the second-floor attic, 25 of which were successfully crossdated against a P. palustris reference chronology located 15 km south in De Soto National Forest (1742–2013). The Deason House chronology anchored against the De Soto time series during the period 1742–1875 ( r = 0.55, t = 4.01, p 〈 0.0001) and extended the reference chronology back to the year 1680 CE. Clustering of cutting- and near-cutting dates from timbers revealed 3 possible stages of construction. First, the house likely existed as a single-pen structure built in the winter of 1835/1836, based on two timbers with wane/bark that were affixed to the original chimney made of clay bricks fired on the homestead. Second, based on the clustering of 1855 cutting dates, we suggest this was the most likely time the original structure was expanded with a vestibule, porch, and larger 4-room house. Finally, six timbers revealed a back addition was constructed in the year 1866. Ground penetrating radar (GPR) helped provide evidence mentioned in written records that the back addition (1866) existed as the detached kitchen then was affixed to the structure ca. 1890. The GPR data revealed geophysical anomalies that indicated the original sites of the detached kitchen, water well, livestock pen, privies, and trash pit. Through the use of dendrochronological analyses and geophysical survey, we were able to provide an updated history of the Deason House construction dynamics and cultural activities of its inhabitants beyond the historical record.

Description: Publication date: Available online 28 December 2016 Source: Dendrochronologia Author(s): Jonathan G.A. Lageard, Peter A. Thomas, Jianquan Cheng In the early twentieth century the woodland at Heald Brow, north-west England, was largely a tree-less pasture, but changing land management practices lead to natural tree colonization and the development of a mixed deciduous woodland with ash ( Fraxinus excelsior ), oak ( Quercus robur ), yew ( Taxus baccata ) and small-leaved Lime ( Tilia cordata ) the main components. The research focused on T. cordata due to its rarity and conservation value, and aimed to investigate the timing of its appearance, rates of reproduction by layering and the effects of competition on its longer-term survival. A small, 0.32 ha area of woodland was mapped using standard field-based survey methods and increment cores were taken to provide minimum age estimates for living stems of all species present. The spatial and temporal data generated led to the development of a new micro-GIS animation method, using ArcGIS software, that visually highlighted secondary woodland establishment and development, and gave novel insights into the competitive interactions that governed the development. Results showed T. cordata colonization in the 1940s and layering developing in the 1960s. The later appearance and rapid establishment of T. baccata with its light-excluding canopy produced high competition scores and undoubtedly restricted further development of the main T. cordata canopy aided by F. excelsior at the periphery. This animation method and associated GIS analyses have potential application in both dendrochronological, wider ecological research and in conservation management.