Wood Anatomy, Tree-Ring Analysis

Ilopango volcano (El Salvador) erupted violently during the Maya Classic Period (250e900 CE) in a densely-populated and intensively-cultivated region of the southern Maya realm, causing regional abandonment of an area covering more than 20,000 km 2. However, neither the regional nor global impacts of the Tierra Blanca Joven (TBJ) eruption in Mesoamerica have been well appraised due to limitations in available volcanological, chronological, and archaeological observations. Here we present new evidence of the age, magnitude and sulfur release of the TBJ eruption, establishing it as one of the two hitherto unidentified volcanic triggers of a period of stratospheric aerosol loading that profoundly impacted Northern Hemisphere climate and society between circa 536 and 550 CE. Our chronology is derived from 100 new radiocarbon measurements performed on three subfossil tree trunks enveloped in proximal TBJ pyroclastic deposits. We also reassess the eruption magnitude using terrestrial (El Salvador, Guatemala, Honduras) and near-shore marine TBJ tephra deposit thickness measurements. Together, our new constraints on the age, eruption size (43.6 km 3 Dense Rock Equivalent of magma, magnitude ¼ 7.0) and sulfur yield (~9e90 Tg), along with Ilopango's latitude (13.7 N), squarely frame the TBJ as the major climate-forcing eruption of 539 or 540 CE identified in bipolar ice cores and sourced to the tropics. In addition to deepening appreciation of the TBJ eruption's impacts in Mesoamerica, linking it to the major Northern Hemisphere climatic downturn of the mid-6th century CE offers another piece in the puzzle of understanding Eurasian history of the period.

Tree-ring anatomy reflects the year-by-year impact of environmental factors on tree growth. Up to now, research in this field has mainly focused on the hydraulic architecture, with ray parenchyma neglected despite the growing recognition of its relevance for xylem function. Our aim was to address this gap by exploring the potential of the annual patterns of xylem parenchyma as a climate proxy.
We constructed ring-width and ray-parenchyma chronologies  from 1965 to 2004 for 20 Juniperus thurifera trees growing in a Mediterranean continental climate. Chronologies were related to climate records by means of correlation, multiple regression and partial correlation analyses.
Ray parenchyma responded to climatic conditions at critical stages during the xylogenetic process; namely, at the end of the previous year’s xylogenesis (October) and at the onset of earlywood (May) and latewood formation (August).
Ray parenchyma-based chronologies have potential to complement ring-width chronologies as a tool for climate reconstructions. Furthermore, medium- and low-frequency signals in the variation of ray parenchyma may improve our understanding of how trees respond to environmental fluctuations and to global change.

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

This paper studies the relationship between apparent density and some anatomical properties of Eucalyptus nitens such as vessel frequency, vessel area, ring width, fiber cell wall thicknesses, and fiber length. The study involved 29 trees from 10 families of Eucalyptus nitens cut from a 17-yr-old plantation in Southern Chile. The properties were determined along the radial direction of the trees by using X-ray equipment and at selected positions through microscope and fiber quality analyzer equipment. The results showed that the anatomical properties of E. nitens did not change gradually from pith to bark, but they were better described by dividing the tree radius into three different wood-zones referred as

Key message Although the radial diameter and wall thickness of conifer tracheids from dry environments are climatic sensitive across the full ring area, each cell parameter has a specific zone in a ring where its climatic response reaches the maximum. Abstract Seasonal dynamics of the timing and rate in cell production and differentiation imprint climate signals into intra-ring variations of anatomical wood structure (e.g. intra-annual density fluctuations). Despite recent methodological advances in quantitative wood anatomy, our understanding of xylem response to climate at the finest scale of intra-ring resolution is incomplete. The goal of this study is to investigate intra-ring changes of tracheid dimensions (cell radial diameter and wall thickness) controlled by moisture stress. Anatomical wood parameters of Pinus sylvestris and Larix sibirica from two drought-susceptible locations in Khakassia, South Siberia, were analysed. We found that inter-annual variation of tracheid parameters regularly exceeds the variation between radial tracheid files. This suggests that the climatic signal is recorded throughout the entire ring. However, each cell parameter has a specific zone in the ring where its climatic response reaches the maximum. The climatic response of the radial cell diameter has a temporal shift across the ring, which is particularly apparent in pine rings. The climatic response of cell wall thickness at the intra-ring scale has a more complex pattern. Our results facilitate investigation of the climate impact on tree rings at the finest intra-ring scale by quantifying the timing of climatic impact on ring structure and identifying specifically when climate impacts the formation of a particular cell. Keywords Conifer trees · Xylem · Quantitative wood anatomy · Tree-ring structure · Climatic response · South Siberia

The results of the dendroarchaeological research carried out on the 16th century altarpiece from the Evangelistas chapel at Seville Cathedral (Spain) are presented. The altarpiece consists of nine panels and was commissioned from the Flemish artist Hernando de Esturmio in AD 1553, who signed the completed work in AD 1555. The research aimed at i) registering information about the processing of the wood and panel making, ii) verifying the AD 1555 construction date, and iii) finding out the provenance of the wood.
Five panels were selected for this research. The observed technological features allowed the reconstruction of the production process from borne (oak wainscots) to the final product and, based on that, two types of panels were described. Dendrochronological results showed that the wood employed in both types of panels represents a rather homogeneous group, implying that the raw material was probably transported to Seville in the same batch, and was prepared and assembled using slightly different methods to meet the requirements stipulated by the contract. Sapwood was identified in 12 of the 33 researched planks. The most recent tree-ring dates in AD 1549. Using a Bayesian approach, we obtained the combined felling date range AD 1549 to 1554 for six of the trees with a 99.7% confidence level. This would allow for a seasoning time of a couple of weeks up to four years, although we cannot discard that some of the other trees were cut earlier and had longer seasoning periods. Interestingly, our research provides evidence that the wood originated from the southwest of Sweden, representing an alternative source to the south-eastern Baltic oak commonly used for panel paintings in northern Europe in the 16th century. This is the first time that such procurement source is reported by dendrochronology in an altarpiece. Wood technological features of the planks and panels are compared to those of Baltic oak wainscots and to contemporary altarpieces in Spain and Portugal. Possible reasons for the use of this alternative procurement source are discussed.

In the Horn of Africa, little is known about temporal changes in hydroclimate owing to the influence of multiple weather systems, the complex terrain, and the sparse instrumental records. Absolutely dated tree-ring records offer the potential to extend our understanding of climate into the pre-instrumental era, but tree-ring studies in this region, and indeed all of tropical Africa, have been rare largely due to lack of an annual climate cycle that reliably produces annual tree-rings. In this study, 40 cores were obtained from 31 Juniperus procera trees growing in the grounds of Ethiopian Orthodox Tewahedo churches in the Gonder region of Ethiopia. The samples were cross-dated using a re-iterative process involving identifying anatomical features from high-resolution images. The tentative ring-width chronologies were revised after the determination of bomb-peak accelerator mass spectrometry radiocarbon dates. Individual series were significantly correlated to the respective master chronologies (r > 0.55; P < 0.05), and expressed population signal values ranged from 0.55 to 0.92. Historical drought years were successfully traced in the chronologies by pointer year analysis. This study confirms that Juniperus procera growing in areas of unimodal precipitation exhibits annual tree-rings and offers the potential as an indirect measure of past climate.

Groundwater is the most important water resource in semi-arid and arid regions such as Iran. It is necessary to study groundwater level fluctuations for managing disasters (such as drought) and water resources. Dendrochronology, that is the use of tree-rings to reconstruct past events such as hydrologic and climatologic events, can be used to evaluate groundwater level fluctuations. In this study, groundwater level fluctuations are simulated using dendrochronology (tree-ring) and artificial neural network (ANN) during 1912-2013. The present study is undertaken by selecting Quercus Castaneaefolia species in the alluvial aquifer of Caspian southern coasts, Iran. Multilayer percepetron (MLP) network is adopted for ANN. Tree-ring diameter and precipitation values are selected as inputs whilst groundwater level is chosen as the output. After the training process, validation to the model is undertaken. The validated network and tree-rings are used to simulate groundwater level fluctuations during the past century. Results show that the integration of dendrochronology and ANN renders high accuracy and efficiency in groundwater level simulation. The simulated groundwater level by dendrochronology can be applied to drought evaluation, drought period prediction and water resources management.

Keywords: Tree-ring, Precipitation, ANN, Caspian southern Coasts.

Branch junctions are mechanically particularly interesting areas of trees, because they have to withstand a combination of static and dynamic loads, from the stem as well as from the branch. In the present work, the local adaptation of material properties at branch junctions was assessed by mapping microfibril angle and tissue density. Images of the density distribution were obtained by computer tomography (CT). Wide angle X-ray scattering (WAXS) was used to determine the microfibril angle distribution with high-resolution around the junctions. The stem tissue around the junctions showed increased density and microfibril angle, which points towards an optimisation for fracture toughness. The tissue at the branch bases showed low density combined with high MFA, which provides deformability and flexibility and might act as protection of the stem against load transmission from the branch.

Wood anatomical features measured in tree-rings are useful indicators of environmental change and wood quality. This study was conducted to investigate the radial variation in tracheid length and growth ring width and to demarcate the boundary between juvenile wood and mature wood of Pinus kesiya Royle ex Gordon grown in Malawi. A total of 90 discs were collected from six families at breast height (1.3 m above the ground) and were measured for tracheid length and growth ring width. The results show that there were statistical significant (P<0.001) differences on tracheid length and growth ring width among the ring numbers in juvenile wood. Tracheid length at first increased rapidly from pith to bark and thereafter increased gradually or remains more or less constant, while growth ring width decreased. However, there were no significant (P>0.05) differences on tracheid length and growth ring width among families across the radius. On the basis of radial variation of tracheid length, the boundary between juvenile wood and mature wood could be marked at ring number 10 from the pith. This should be taken into account when planning for forest management and product manufacturing using Pinus kesiya grown in Malawi.

The mechanistic understanding of isotope fractionation processes is increasing but we still lack detailed knowledge of the processes that determine the isotopic composition of the tree-ring archive over the long term. Especially with regard to the path from leaf photosynthate production to wood formation, post-assimilation fractionations/processes might cause at least a partial decoupling between the leaf isotope signals that record processes such as stomatal conductance, transpiration and photosynthesis, and the wood or cellulose signals that are stored in the paleophysiological record. In this review, we start from the rather well understood processes at the leaf level such as photosynthetic carbon isotope fractionation, leaf water evaporative isotope enrichment and the issue of the isotopic composition of inorganic sources (CO 2 and H 2 O), though we focus on the less explored 'downstream' processes related to metabolism and transport. We further summarize the roles of cellulose and lignin as important chemical constituents of wood, and the processes that determine the transfer of photosynthate (sucrose) and associated isotopic signals to wood production. We cover the broad topics of post-carboxylation carbon isotope fractionation and of the exchange of organic oxygen with water within the tree. In two case studies, we assess the transfer of carbon and oxygen isotopic signals from leaves to tree rings. Finally we address the issue of different temporal scales and link isotope fractionation at the shorter time scale for processes in the leaf to the isotopic ratio as recorded across longer time scales of the tree-ring archive.

Mean sensitivity continues to be used in dendrochronology despite a literature that shows it to be of questionable value in describing the properties of a time series. We simulate first-order autoregressive models with known parameters and show that it is a function of variance and autocorrelation of a time series. We then use 500 random tree-ring data sets with unknown parameters and show that  it is at best equivalent to the standard deviation of a time series in cases without high autocorrelation and is an inefficient estimator of the coefficient of variation. It is hard to justify the use of  mean sensitivity as a useful, descriptive statistic in dendrochronology on theoretical or empirical grounds. It is better to make a thorough evaluation of the time series properties of a data set and we suggest various avenues for doing so including some that are maybe unfamiliar to most dendrochronologists including generalized autoregressive conditional heteroscedasticity (GARCH) models.

Dendroecological research uses information stored in tree rings to understand how single trees and even entire forest ecosystems responded to
environmental changes and to finally reconstruct such changes. This is done by analyzing growth variations back in time and correlating various
plant-specific parameters to (for example) temperature records. Integrating wood anatomical parameters in these analyses would strengthen
reconstructions, even down to intra-annual resolution. We therefore present a protocol on how to sample, prepare, and analyze wooden
specimen for common macroscopic analyses, but also for subsequent microscopic analyses. Furthermore we introduce a potential solution for
analyzing digital images generated from common small and large specimens to support time-series analyses. The protocol presents the basic
steps as they currently can be used. Beyond this, there is an ongoing need for the improvement of existing techniques, and development of new
techniques, to record and quantify past and ongoing environmental processes. Traditional wood anatomical research needs to be expanded to
include ecological information to this field of research. This would support dendro-scientists who intend to analyze new parameters and develop
new methodologies to understand the short and long term effects of specific environmental factors on the anatomy of woody plants.

El carbón vegetal es un insumo energético muy utilizado en diversos segmentos de la industria siderúrgica, metalúrgica, cimientos y otras, presentando importancia económica e histórica en Brasil. Una de las formas de determinar la procedencia del carbón vegetal es identificando este material, lo que permite comprobar la legalidad de explotación, y cual es su posible origen. Este trabajo tuvo como objetivo describir la anatomía de la madera y del carbón de Pouteria macrophylla (A.DC.) Eyma y Micropholis guianensis (A.DC) Pierre, y comparar las características antes y después del proceso de carbonización, con la finalidad de suministrar más información sobre la estructura de estos materiales. Los cuerpos de prueba se carbonizaron en horno de mufla, a temperatura máxima de 450 ºC durante un período de aproximadamente 6 horas y 30 minutos. La elevada contracción de las células de Pouteria macrophylla y Micropholis guianensis durante el proceso de carbonización causó alteraciones dimensionales, que no perjudicaron el aspecto cualitativo de las características anatómicas, siendo posible la distinción de especies, e identificación del leño carbonizado a través de la descripción de la madera.

WODAN is an integrated on-line wood and charcoal database that can be used for archaeological and biological studies and investigations in Ireland and beyond. It will serve both as a digital archive and a powerful tool for scientific research for environmental analysis both within Ireland and Internationally. For the first time, this database will allow specialists and non-specialists alike to search and query charcoal and wood results from excavations in Ireland and beyond. The development of an on-line database application is a fundamental departure from other environmental databases. It makes the catchment area of the database far greater than any previously designed environmental database.

At all times there will only be one, central, updated version available. It was designed with all known methods of charcoal and wood analysis in mind, in order to enable as many people as possible to use it. The database was developed in two stages. Firstly a prototype (alpha product), that served as a test bed for demonstration, amendment and refinement was developed. During this period, the team concentrated on implementing many advanced features that help to illustrate the capabilities of our approach. The second, or beta phase, involved stabilizing the system and ensuring that that overall user experience was successful. The development of the WODAN database and web application has all been carried out using free open source software. The content or data component of the WODAN resides in a MySQL relational database whose schema is based upon the standardised fields. The construction of the web interface to access the WODAN database is carried out using several components including Ruby on Rails (RoR), CSS and HTML.

Most commercial archaeological companies, universities and research institutions in Ireland are keen to use the WODAN database as a permanent digital archive of their wood and charcoal results from Irish excavations. Almost all specialists who have worked on Irish material are currently entering data into WODAN. 24 profiles have been created. Over 370 sites have been added, including approximately 1500 charcoal and 1000 wood samples. The scope for synthesis is immense. The database will be used as a springboard for environmental research. The wide ranging scope and nature of the data collection will mean that it will be possible to address important questions on the nature of woodland throughout Ireland’s history. Standardization of methods was one of the key aims of the WODAN project. This has been achieved through the development of database fields through numerous discussions and workshops. As a result, all specialists working in Ireland currently use the same recording sheets and methods. An international element has been added with wood and charcoal specialists from England, Belgium, Holland, France, Germany, Australia and America, all of whom have played an active role in the creation of the database.

In southern Spain, the Cazorla Mountains (500-2,100 m a.s.l.) have supplied construction timber from black pine (Pinus nigra Arn.) for buildings and ships since at least the Middle Ages. To establish the age and provenance of wooden cultural heritage originating from this area, well replicated long-span chronologies are needed. Old-living trees occur at high elevations, whereas many historical timbers originated from lower altitudes, hence crossdating possibilities were questionable. To assess the potential of this species for the development of a multi-millennia tree-ring dataset with living trees and historical timbers for the western Mediterranean, we developed four ring-width chronologies along the circa 1,000 m altitudinal range of black pine in these mountains, and examined crossdating patterns and climate-growth responses along with altitude and through time. Teleconnections with other Iberian and Mediterranean tree-ring data were also tested. A well replicated chronology spanning AD 1331-2009 was obtained at the upper site, while lower elevations delivered shorter chronologies. Similarity among chronologies and responses to climate were dependent on elevation. Tree-ring width was negatively related to temperature in previous late summer and positively to February-March, whereas precipitation had an opposite effect; some negative influence of early summer temperature was also observed. However, growth responses were rather unstable throughout the 20th century. These chronologies showed good tele- and heteroconnections with conifer chronologies from Iberia, northern Morocco and Turkey, evidencing the existence of a common macroclimatic signal, which also varied along with elevation. The relevance of these results for dendro-historical studies is discussed.

Sigmoid curve was well known as a general curve to fit the growth behavior of cell, organism, or population in accordance with limitation of genetic, environmental capacity and density in their habitat. Unfortunately, many growth behaviors did not follow the basic sigmoid curve because the prerequisite assumptions were not fulfilled by actual condition. In this study, linear and nonlinear function were used to modify the exponential curve become a new growth curve which could be used in more general cases than available model nowadays. Linear modification developed basic sigmoid curve. Nonlinear functions were proposed to modify the exponential curve in this study were named after: Second order polynomial (quadratic), logarithm and second order logarithm. Basic sigmoid curve and logarithm modification on exponential curve resulted curve which always had one asymptote line so it was suitable for fitting the fiber length data at every growth ring if the samples were completely made from juvenile and mature period. If the samples came from the juvenile period alone or the researcher had not certainly sure yet, quadratic or second order logarithm modification were highly recommended to be used because those equations could result two, one, or none asymptote line. Second order logarithm was generally become the best one among others. Mathematical curve fitting on fiber length growth in this study was successfully pointed the transitional age of juvenile/mature period of Teakwood with high coefficient of determination and low standard deviation. Based on recommended mathematical method, the transitional age of Teakwood was 9-12 years old. It was more precise than visual assessment conducted by 30 undergraduate students in wood science and technology class in Bogor Agricultural University which resulted 7-15 years old. The mathematical method reduced the subjectivity and variability compared to visual assessment.

La madera es un recurso natural renovable que proporciona materia prima para la construcción, generación de energía, fibras para la producción de pulpa y papel, paneles y tableros, y más recientemente para biocombustibles y biomateriales, lo que la hace el quinto producto comercial más importante del Palabras clave: Maderas duras, xilogénesis, expansión celular, pared celular secundaria, expresión genética.

En este trabajo se cuantifica la variabilidad radial y apical de los canales resiníferos de pino radiata (Pinus radiata) de 14 años. Se determinó la frecuencia y el tamaño de los canales resiníferos en muestras microtomadas usando un software comercial. Las muestras fueron extraídas de árboles en pie presentando tres niveles diferentes de resinación externa, es decir, moderada/leve, e intensa. Se evaluó la variabilidad de los canales resiníferos según la posición radial a tres diferentes alturas: base, DAP, y al comienzo de la copa del árbol.

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg−1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg−1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg−1) and bark (6.0 μg kg−1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.

Plant growth in Mediterranean landscapes is limited
by the typical summer-dry climate. Forests in these areas
are only marginally productive and may be quite susceptible
to modern climate change. To improve our understanding of
forest sensitivity to annual and seasonal climatic variability,
we use tree-ring measurements of two Mediterranean evergreen
tree species: Quercus ilex L. and Arbutus unedo L. We
sampled 34 stems of these species on three different types of
substrates in the Peyne study area in southern France. The
resulting chronologies were analysed in combination with
38 yr of monthly precipitation and temperature data to reconstruct
the response of stem growth to climatic variability.
Results indicate a strong positive response to May and
June precipitation, as well as a significant positive influence
of early-spring temperatures and a negative growth response
to summer heat. Comparison of the data with more detailed
productivity measurements in two contrasting years confirms
these observations and shows a strong productivity limiting
effect of low early-summer precipitation. The results show
that tree-ring data from Q.ilex and A.unedo can provide valuable
information about the response of these tree species to
climate variability, improving our ability to predict the effects
of climate change in Mediterranean ecosystems.

Tree-ring carbon and oxygen isotope ratios from live and recently dead trees may reveal important mechanisms of tree mortality. However, wood decay in dead trees may alter the d 13 C and d 18 O values of whole wood obscuring the isotopic signal associated with factors leading up to and including physiological death. We examined whole sapwood and a-cellulose from live and dead specimens of ponderosa pine (Pinus ponderosa), one-seed juniper (Juniperous monosperma), piñon pine (Pinus edulis) and white fir (Abies concolor), including those with fungal growth and beetle frass in the wood, to determine if a-cellulose extraction is necessary for the accurate interpretation of isotopic compositions in the dead trees. We found that the offset between the d 13 C or d 18 O values of a-cellulose and whole wood was the same for both live and dead trees across a large range of inter-annual and regional climate differences. The method of a-cellulose extraction, whether Leavitt-Danzer or Standard Brendel modified for small samples, imparts significant differences in the d 13 C (up to 0.4%) and d 18 O (up to 1.2%) of a-cellulose, as reported by other studies. There was no effect of beetle frass or blue-stain fungus (Ophiostoma) on the d 13 C and d 18 O of whole wood or a-cellulose. The relationships between whole wood and a-cellulose d 13 C for ponderosa, piñon and juniper yielded slopes of~1, while the relationship between d 18 O of whole wood and a-cellulose was less clear.

This study aimed to investigate in Benin the effect of climate variability on growth dynamics and anatomical features of Strychnos spinosa wood, a wild edible fruit treeter widely spread through tropical Africa to South Africa, which plays several roles in the daily life of rural communities both for humans and animals. We collected stems disks from different climatic zones and different ecosystems (National parks and classified forests,t ecosystems,) in Benin. The stem disks were dried, polished gradually using sand paper of gradually finer grit size from 400-2000. Air cCompressedor air was used to remove the dust. The disks were cut, soaked in water in order to make them soft. Thin sections were then taken using the a sledge microtome and stained using the protocol described by Gärtner et al. (2015). Standard dendrochronological and wood anatomical approaches were then combined to describe the wood features. The First results showed that S. spinosa forms distinct growth ring boundaries and in some cases has exhibits wedging and missing rings. They showed a growth pattern. The species is diffuse porous . It showswith vessels grouped in tangential or radial direction with some solitary vessels. The preliminary results indicate the age range of the studied individuals is mostly about 30 years old.  These preliminary results show that dendrochronology can be apply on S. spinosa to assess its growth and anatomical features but also to assess the effect of climate gradient on these parameters. The study can provide useful informationwill be used for the best individuals identification that could be used for the plant improvement and ideotypes creation for its introduction in the traditional agroforestry systems.to characterize species growth dynamics and response to climate, so that to recommend sustainable management and domestication options into regional traditional agroforestry systems.

Key words: Strychnos spinosa, tropical dendrochronology, wood anatomy, tree-ring, Benin

We reconstructed air temperature for two periods in the growth season from cell dimension and cell number variability in cross-dated tree rings of Larix cajanderi Mayr. from northeastern Siberia. Thirteen tree-ring chronologies based on cell size, cell wall thickness, and cell number were developed for AD . No clear evidence was found of an age-related trend in cell dimensions in the sampled materials, but cell numbers were correlated with cambial age. The chronologies contain strong temperature signals associated with the timing of xylem growth. We obtained reliable reconstructions of mean June temperature from the total cell number and July-September temperature from the cell wall thickness of latewood. June temperature and July-September temperature covaried for most of the period from AD 1642 to AD 1978. After that time, June temperature became cooler relative to July-September temperature. This difference caused disproportional changes in earlywood tracheids because of the late start of growth and cool conditions in June followed by warming during the rest of the season. The identification of this unusual recent change has shown that intraseasonal resolution may be achieved by cell dimension and cell number chronologies.