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Cedrela fissilis is a tree species widely distributed in the tropical biomes of South America. This species has visible annual growth rings and can live for several centuries. The present study aims to (i) develop a chronology of C. fissilis to the Southern Brazilian Plateau using traditional dendrochronological methods, (ii) validate the dendrochronological dating using the radiocarbon (14C) bomb pulse method, and (iii) determine the influence of temperature and precipitation variations and their teleconnections with the tropical Pacific Ocean temperatures on the annual radial growth of this species. The ring width chronology was developed using 24 C. fissilis trees. The Schulman years of 1957, 1962, 1963, 1966, 1969 and 1974 were independently dated using the 14C bomb pulse methodology by accelerator mass spectrometry (AMS). Tree-ring indices were compared with temperature and precipitation records from stations around the study forest. The chronology covers the period 1907–2018 (111 years) and is well replicated (> 10 trees) from 1941 onwards. Statistics commonly used in dendrochronology indicate that the chronology is highly reliable and of good quality (mean series intercorrelation r = 0.49; Rbar = 0.30; EPS = 0.86; MSI = 0.40). The 14C bomb pulse of selected calendar years showed that the trees were accurately dated using the classical cross-dating approach. Precipitation from November to December (wet period) is positively correlated with tree growth (r = 0.36, n = 49; p<0.05). In addition, variations in temperature from May to July are positively correlated with ring width (r = 0.39, n = 49; p<0.05), suggesting that C. fissilis growth is favored by abundant rainfall during the growing season and above-average winter temperatures. Interannual variation in the chronology is partially modulated by El Niño 3.4 (East Central Tropical Pacific Sea Surface Temperature) during Oct-Dec (r = 0.27, n = 68, p<0.05). The growth of C. fissilis trees is directly dependent on climate variability, suggesting that more abundant precipitation and higher winter temperatures, as projected for the future climate of southern Brazil, will have a positive effect on tree growth. However, prolonged droughts and high temperatures during the growing season will have a negative impact on tree growth, even in humid forests with high soil moisture content. [Display omitted] • A 111-year tree-ring chronology (1907-2018) for Cedrela fissilis in Southern Brazil, validated by 14C bomb-pulse method. • Positive relationships between tree growth, rainfall (Nov-Dec), and above-average winter temperatures (May-Jul). • Teleconnections with Pacific (Niño 3.4) and Atlantic SSTs modulate spring rainfall and C. fissilis growth in SE Brazil. • Prolonged El Niño and La Niña events (>2 years) significantly impact growth, indicating climate sensitivity. [ABSTRACT FROM AUTHOR]

Climate variations are influencing the growth dynamics of forests, with direct consequences on their biomass productivity. The scientific community, concerned with refining the understanding of tree-climate interactions, has recently used tree-ring density to elucidate ecological mechanisms that may be overlooked by earlywood, latewood, and total tree-ring widths. In this study, we model the sensitivity of intra-annual wood density in tree-rings for 15 species distributed across a broad bioclimatic and biodiverse gradient in the Mexican Republic. Maximum, minimum, latewood, and earlywood density (MaxD, MinD, LWD, and EWD, respectively) were associated with climatic data through correlation analysis and mixed-effects models. Maximum temperature (T MAX) and precipitation (P) stand out as key drivers of temporal density fluctuations, notably influencing MaxD and LWD as indicators of hydroclimatic regime changes. MinD and EWD are less responsive but prove valuable in gauging environmental sensitivity. Abies religiosa from the Southern Semi-Arid Highlands and Picea martinezii from Mediterranean California were the most responsive species to climate variables. These results open new paradigms for densitometry as a proxy for ecological processes that species face in anticipating dieback phenomena, mortality rates, and resilience mechanisms, with implications for productivity and carbon rates in the face of predicted climate variations. However, the wood density-climate relationship is even more complex, and integrative research combining other proxies (e.g., wood anatomy and chemical composition) is recommended to refine wood density variations and understand the causes of the interspecific differences found in this study. [Display omitted] • Intra-annual wood density represents robust proxies of hydroclimate variability. • Intra-annual wood density responds to climate, regardless of species or ecoregion. • Max temperature is the main factor limiting wood density, followed by precipitation. • Max wood density stands out as one of the most robust tree-ring hydroclimatic proxy. [ABSTRACT FROM AUTHOR]

• We report the first studies of tree growth dynamics of the SDTF of the Marañón valley. • Higher growth rates were found in Cordia iguaguana and Cedrela kuelapensis. • Cedrela kuelapensis presents high growth rates in relation to the congeneric species of the neotropical region. • Populations of endemic species in the area could be mainly of young individuals. Seasonally dry tropical forests (SDTF) currently occupy only 10% of the original area of their natural distribution. In the Marañón river valley, north western of Peru, occurs one of the most important SDTF of the neotropics. It has an endemic woody flora that represent 32% of the species, being threatened by its increasing fragmentation, and the knowledge of the ecology, forestry and conservation of the tree species is scarce. In this context this work presents the result of evaluation of the wood anatomy with emphasis to growth ring analysis, dating trees and stem growth rate determination of four tree species: Anadenanthera colubrina (Vell.) Brenan, Cedrela kuelapensis T.D. Penn. & Daza, Cordia iguaguana Melch. Ex I.M. Johnst., and Esenbeckia cornuta Eng., the last three being endemic and threatened with extinction. Our results determined that Cedrela kuelapensis showed the highest radial growth of the stem in relation to the other congeners of the neotropical region. Lower stem growth was observed for E. cornuta trees, according to the pattern of other tropical species. The results also indicate that populations of C. iguaguana and Esenbeckia cornuta in the zone are mainly composed by young trees exhibiting strong anthropic pressure due to the quality of their timber and, in consequence, more efforts are needed in the management of these resources to guarantee their sustainability. [ABSTRACT FROM AUTHOR]

The expected intensification of the dry season, and concentration of rainfall during the wet season, can disrupt tree growth and regional biodiversity in the Cerrado-Pantanal transition zone. Thus, this study aims to assess the climatic responses of Hymenaea stigonocarpa tree growth, a common tree species in this region. Incremental cores were collected at breast height (ca. 1.3 m) from 67 trees to construct a dendrochronological series to correlate annual growth with local meteorological variables and large-scale atmospheric circulation indices from the Pacific and Atlantic Oceans. Significant positive correlations were observed between tree growth and the Pacific Ocean indices. Maximum and average air temperatures of the previous dry season negatively influenced growth, while precipitation at the beginning of the growth season (November) positively influenced growth. Tree growth was not correlated with temperature or rainfall during the wet season. However, at the end of the wet season (February), tree growth was negatively correlated with air temperature and positively correlated with rainfall, but the relationship shifted in the next month (March) suggesting that soil water saturation reduced growth. Our results indicate that dendrochronological studies of H. stignocarpa are useful for assessing the environmental change on the Cerrado-Pantanal ecotone. Furthermore, variations in water availability and temperature associated with changes in large-scale oceanic circulation and local meteorological conditions will impact the growth dynamics of this important Cerrado tree species. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The historical nutrition of a P. taeda forest-plantation was analyzed by μ-XRF techniques. • A method to quantify Fe, Mn, Ca, K, S and P in spots of 1 mm (wide) in wood cores was development. • Tree-ring nutrient trends decrease (Ca, Mn, Fe, P) and increase (K, S) from the pith-bark direction. • Nutrients variability presented strong correlation with the rainier and hotter season. • Fertilization monitored by ring nutrients, Ca/Mn (soil-pH indicator) and K/Ca molar ratios (cambium activity indicator). Abstract Tree-rings are sensitive indicators of soil chemical changes. X-ray fluorescence microanalysis (μ-XRF) can reveal the elemental distribution pattern along these rings. However, reports on quantitative μ-XRF methods targeted to wood analysis are scarce. This study aimed to analyze iron (Fe), manganese (Mn), calcium (Ca), potassium (K), sulfur (S) and phosphorus (P) in annual tree-rings of wood cores cut from 24 trees of 17 year-old Pinus taeda planted in soil amended with six doses of composted pulp-mill sludge (CPMS). The nutrient concentrations were accessed using calibration curves built with spiked P. taeda wood pellets. Calcium and Mn content decreased from the pith to bark direction; K and S decreased from the pith up to 3rd tree-ring and, then, increased to the bark. Iron and P slight decreased from the pith up to the 13–14th tree-ring. Calcium, K and S presented strong and positive correlation with the rainier and hotter season (r > 0.4, p < 0.05). The CPMS increased the Ca, K, Fe and S and decreased Mn and P concentration in P. taeda wood in the 2nd–5th years. Furthermore, the P. taeda annual tree-ring molar ratios of Ca/Mn and K/Ca were good indicators of soil-pH and wood cambium activity. The μ-XRF methodology, as non-destructive method of nutrient concentration analysis in tree-rings, revealed potential uses in monitoring soil fertilizer treatments. [ABSTRACT FROM AUTHOR]

Pinus taeda is a principal conifer tree species and has long been used in forest plantations in Southern Brazil. At the same time, experiments have been carried out in order to determine the wood productivity concerning the economic, social and sustainable forest management practices. In that sense, the organic fertilizers, such as the biosolid residues from pulp and paper industries, are one of the alternatives to achieve this sustainability. Nevertheless, few studies addressing this objective have been reported in Brazil. This study aimed to analyze the growth responses of loblolly pine trees treated with different doses of composted pulp-mill sludge and to propose a management guide based on a wood production simulation. A randomized block design with four replicates for every six treatments - control, 20, 40, 60, 80 and 100 t ha −1 of composted pulp-mill sludge - were carried out in an experimental plantation located in Arapoti, Paraná state, Brazil. Ten 17 year-old-trees for each treatment were selected, the stem variables were analyzed and the stand wood productivity for the optimal dosage was simulated. The trees were significantly influenced by the application of the composted pulp-mill sludge, increasing up to 24, 37 and 127% in stem diameter, height and volume, respectively, and the rotation of the pine plantation control and treated stands was 33 and 21 years, respectively. The forest management applied for a 21-year harvesting cycle (thinning at 7 and 13 years) with 84 t ha −1 of composted pulp-mill sludge resulted in a wood productivity of 11.9 m 3 ha −1 or 5.04 Mg ha −1 per year. The results confirm the potential application of pulp-mill sludge as a fertilizer to improve the wood productivity of forest plantations established in poor-nutrient sites. Also, the forest management plans, using the guide proposed, could be replicated in loblolly pine and other tree species plantations according to the end use of wood. [ABSTRACT FROM AUTHOR]

Water erosion is an important degradation process, which results in loss of soil, reduction in agricultural productivity, and causes severe environmental impact. Dendrogeomorphology has methods in which the structure of the wood of the stem and roots of tree and shrub species affected by sediment deposition or by root exposure is analysed, to establish the chronology of erosive events. The objective of the present work was to describe the modifications and scar formation in Schizolobium parahyba growth rings, attributed to the effect of roots exposure for determining the first year of exposure. The study area presents erosion features, such as gullies, with the consequent exposure of tree roots. The growth rings and the scars formed by the flow of water and soil particles were analysed in cross-sections of exposed roots to date the erosion processes. This paper demonstrates the potential of S. parahyba for dendrogeomorphological studies, validating dendrogeomorphology as a research tool in tropical climate. Scars used for erosion dating in cross-sections have been proven as good indicators of geomorphic processes. The relevance of this work is to become the first attempt in tropical regions to date erosion processes using dendrogeomorphological techniques on exposed roots. [ABSTRACT FROM AUTHOR]

Xerophytic thickets occur along the southwestern part of Madagascar. Although providing a wide variety of resources and services to the local population, this particular vegetation is subjected to deforestation. This study focuses on linking dendroclimatology and dendroecology by examining the spatial and temporal variability of the ecological growth conditions. Information from tree rings was retrieved, on one hand, to identify the problem of the limiting effects of past climate on growth and, on the other hand, to show how local environment takes part in the growth pattern of South Soalara species, in the southwestern part of Madagascar. Methods and principles of dendrochronology were applied on nine species belonging to seven botanical families. A total of 42 stem discs from 3 to 5 trees per species were collected at 30 cm height. All discs exhibited visible tree rings, but anatomical distinctness varied between species. This study highlighted the annual formation of tree rings through successful crossdating techniques. Then, from the nine constructed chronologies, species were grouped into three clusters. Analysis between precipitation and radial growth showed that the response to climate occurred mainly in rainy season. Large-scale climatic drivers such as sea surface temperature (SST 1 1 SST = Sea surface Temperature. ) of ENSO 2 2 ENSO = El-Niño Southern Oscillation. regions revealed a teleconnection with tree growth in cluster 1. Mean radial increments were computed from the measured tree ring width and varied from 0.66 to 1.98 mm year −1 , showing that those species are slow-growing. All species were recorded as having a certain dendrochronological potential, which was ranked as useful for Rhizogum madagascariense and Terminalia gracilipes, poor for Gyrocarpus americanus and problematic for the other species. It is recommended to increase the number of wood samples and to provide more knowledge on the characteristics of the species in order to improve the quality of the chronology and the climatic signal on tree rings. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The development of tree-ring chronologies of tropical trees allows to reconstruct the environmental history of the Neotropics on extensive temporal and spatial scales. This article presents a historic, state-of -the-art overview/review of dendrochronological studies in Perú, a megadiverse country in its flora, types of climate and ecosystems. We reviewed all available information on dendrochronological studies by assessing scientific articles in indexed, and non-indexed journals as well university thesis repositories. Dendrochronological studies began in the late 1980s and have botanically involved 20 families, 34 genera and 52 tree species. The most studied families are Fabaceae (16 studies), Meliaceae (12), Rosaceae (06), and Bignoniaceae (04), and the most studied genera were Cedrela (13), Polylepis (08) and Prosopis (06). The development of chronologies was mainly applied in climatic reconstructions, forest conservation and management. We identify underrepresentation or sampling gaps regarding climatic and geographic complexity. The high tree diversity of Perú constitutes a natural laboratory to develop tree-ring studies to better understand the growth and functioning of tropical tree species, their interaction with climate, and to derive climate reconstructions during the last centuries. This review aims to contribute to the direction of future dendrochronological studies in Perú. [ABSTRACT FROM AUTHOR]

• The extreme drought period in 2014 combined with 37% throughfall reduction was studied. • Potassium (K) fertilization increased changes in vessel traits in response to drought. • After rehydration, K fertilization enhanced the recovery of xylem hydraulic conductivity. • The positive effects of K on tree growth were maintained throughout the rotation. • A 37 % throughfall reduction only affected tree growth for the first 2.5 years after planting. Most Eucalyptus plantations in Brazil are located in regions currently experiencing periods of water shortage, where fertilizers such as potassium (K) are intensively used to achieve high productivity. In a changing environment, improving our understanding of the effects of K nutrition on tree growth rates and xylem plasticity across tree ages as a function of climate is crucial for forest management. The objective of this study was to gain insight into the interactive effects of K fertilization, water availability, and tree age on stem growth and changes in xylem traits of E. grandis trees over a full rotation. Changes in growth and xylem traits in response to a severe drought that occurred in 2014 were also studied. An experimental plantation of E. grandis trees was established in São Paulo, Brazil and monitored over a full 6-year rotation period. The experiment consisted of a split-plot design with two water supply regimes (37 % throughfall reduction vs undisturbed throughfall) and two fertilization regimes (K supply vs control). Basal area increment (BAI) was monitored using band dendrometers at 14-day intervals from 1 to 6 years after planting. Xylem traits including wood density (WD), cell wall fraction (CWF), cell density (CDen), theoretical xylem specific hydraulic conductivity (Kst), vessel diameter (VD), vessel density (VDen), vessel area (VA), and the vulnerability index (VI) were measured in 6-month periods (rainy and dry seasons) throughout the rotation. K fertilization increased BAI by a factor of 3 in plots where throughfall was not disturbed but led to an interruption of tree growth during the severe drought in 2014. The growth patterns showed a positive effect of K for growth recovery following drought. Throughfall reduction affected growth only in K-fertilized trees and up to 30 months of age. K fertilization also increased changes in xylem traits in response to drought in E. grandis trees. The main changes occurred in vessel traits, with a 53 % decrease in Kst during the drought but recovery was rapid after the first rainfall events. High plasticity was also observed for WD, CWF, CDen, and VI. [ABSTRACT FROM AUTHOR]

• Eucalyptus growth was recorded biweekly over two years on a tropical soil. • Sewage sludge application, based on N criteria, with P, promoted higher production. • Tmin, rainfall, and PET influenced Eucalyptus growth. • Lower growth occurred in the dry winter compared to the hot summer. • Sewage sludge applied with B sustained Eucalyptus growth during the dry winter. Sewage sludge (SS) application to Eucalyptus urograndis plantations can result in wood yields rivalling those achieved when mineral fertilizers are used. While climatic conditions determine Eucalyptus growth and wood production, the use of fertilizers containing boron (B) can mitigate the impact of drought on Eucalyptus growth. We hypothesized that SS application supplemented with P and B would improve growth and wood production of Eucalyptus planted in the Cerrado region of Brazil. We evaluated wood production and the influence of two years of meteorological seasonality on trunk cross-sectional area (TCSA) growth of Eucalyptus planted on an infertile Oxisol treated with SS. The experiment was conducted on a 54-month-old Eucalyptus urograndis plantation. The treatments were: i) control; ii) two levels of mineral fertilization; iii) seven SS treatments with or without P and/or B. SS application, based on tree N requirement, supplemented with P, resulted in wood production like those produced under mineral fertilization. Within climate variables, rainfall, potential evapotranspiration, and minimum air temperature had the largest influence on Eucalyptus TCSA growth. There was lower accumulated TCSA growth in the cold and dry winter season compared to the hot and rainy summer. However, SS application supplemented with B promoted TCSA growth, enhancing Eucalyptus tolerance to drought periods. In summary, SS supplemented with P and B is a valuable option as an organomineral fertilization management in Eucalyptus plantations, as it improved trunk growth during drought periods as well as wood volume production. [ABSTRACT FROM AUTHOR]

Long-term analysis of tree growth using annual tree rings is increasingly in demand for tropical tree species. The basis of these studies has traditionally been the anatomical identification of the annual ring boundary. However, the structure of these annual rings has been sparsely explored for complementary physical and chemical wood traits. Here, we explore the relationships among wood density features and chemical elements (S, K, Ca, Mn) involved in the annual tree ring formation of 12 tropical tree species from non-flooded forest in the southern Amazon basin. Transverse wood sections were used for each species to determine: 1) macroscopic distinction (radial growth and wood density), 2) microscopic analyse of vessels, axial and ray parenchyma (anatomy) and 3) X-ray densitometry (physical) and X-ray fluorescence (chemical). For some species, the profiles of wood density, and Ca and Mn content showed intra- and inter-annual patterns that allowed to define and characterize the growth boundary of tree rings. Ca, K and S were mainly distributed in axial parenchyma cells, and around vessels, whereas, Mn was mainly distributed in fibres. Our results showed significant species-specific correlations between tree-ring width, density and concentrations of Ca, K and Mn. The anatomical characterization and the complementary information provided by the density and chemical profiles in some Amazonian species can represent a valuable proxy to improve the definition of annual ring-boundaries and improve the understanding of long-term growth and physiological patterns. [Display omitted] • Physical and chemical parameters for tropical tree-rings delimitation are analysed. • Novel techniques of wood anatomy, X-ray densitometry and X-ray fluorescence were used for tree-ring microanalysis. • Wood density and elements patterns are associated to growth rings anatomical markers. • Anatomical, physical and chemical parameters show inter-correlations related to the type of ring. [ABSTRACT FROM AUTHOR]

• 3-year of 80% throughfall reduction reduced basal area by 73% and height by 95%. • After water stress ended, trees showed high growth recovery ability. • After water stress ended, trees grew 97% more in basal area than control trees. Eucalyptus plantations are already planted in - or expanding to - water-limited regions with a high risk of severe drought. In future drier and more variable climate including extreme events, the ability of trees to recover after severe droughts emerges as a crucial for the sustainability of forest plantations. An original experiment involving 80% reduction in throughfall was set up in Brazil to gain insight into the responses of Eucalyptus grandis trees to prolonged (3-year) extreme water deficit and the ability of this species to recover following water stress. Our study focused on the changes in basal area, stem radius, and total height measured by high-temporal resolution dendrometers and periodical surveys of trees affected by 80% throughfall reduction (treatment group) and in a control group. The differences in basal area, stem radius, and total height growth rate were compared between groups over (i) 37 months of 80% throughfall reduction and (ii) 31 months following the end of 80% throughfall reduction. The correlations among growth rates, stem radius fluctuations, and meteorological variables in each group were determined to gain insights into the trees' responses to environmental conditions and stem water status. The 80% reduction in throughfall over 3 years significantly reduced tree growth rates by 73% in basal area and 95% in total height. However, under normal water availability following throughfall reduction, the basal area growth rate of water-stressed trees was 97% higher than that of the control trees while total height growth rate was only 8% higher. Despite the severe water stress, no tree mortality was observed. Trees recovered 51% of their basal area over the 31-month recovery period. In contrast, only 5% of total height was recovered. In the treatment group, rapid responses to variation in rainfall events were observed during the 80% throughfall reduction period. Also, correlations between stem radius fluctuations and vapor pressure deficit indicate increased transpiration following the end of throughfall reduction. These relationships indicate high conservation of the integrity of the xylem vascular system over the 3 years of 80% throughfall reduction, a key factor in the increased resilience of the trees. In the absence of tree mortality, our results suggest the 80% throughfall reduction had a severe impact on tree growth but demonstrate great recovery ability of Eucalyptus grandis trees in basal area growth following such a severe water deficit. [ABSTRACT FROM AUTHOR]

• Elemental distribution images in wood surface of tropical tree species were built. • Parenchyma, fiber and vessel present different trace element compositions. • Element accumulations in heartwood and sapwood are different from the same species. The distribution of trace elements in tree rings although poorly known may be useful to better understand environmental changes, pollution trends, long-term droughts, forest dieback processes, and biology of trees. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used for imaging micronutrients and potentially toxic elements distribution, allowing the investigation of trace elements at high spatial resolution within the tree rings. To ensure a more efficient determination of micronutrients and potentially toxic elements, LA-ICP-MS instrumental conditions were optimized and carbon, a major element in wood, is used as an internal standard during analysis to correct for random fluctuations. Spatial distributions maps of Ba, Cu, Fe, Mn, Ni, and Pb in growth layers of six tropical tree species were built-up using the LA-iMageS software, namely: Amburana cearensis (Fabaceae), Cedrela fissilis (Meliaceae), Hymenaea courbaril (Fabaceae), Maclura tinctoria (Moraceae), Parapiptadenia zehntneri (Fabaceae), Peltogyne paniculata (Fabaceae). A correlation between the trace element composition and different cell types (parenchyma, fiber, and vessel) was distinctly observed. It was observed a general pattern of Ba, Cu, Ni, Mn, and Pb accumulation mainly in the axial parenchyma and vessels. But the elemental composition of xylem cells is strongly species dependent. The multivariate analysis also points to a distinct accumulation of minerals between heartwood and sapwood in the same species. Imaging both essential and deleterious element distributions in the tree rings may improve visualization and can effectively contribute to understanding the lifetime metabolism of trees and evaluating the effects of environmental changes related to climatic seasonality, pollution, and future paleoclimate reconstructions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A protocol for obtaining long histological sections of medium-high-density wood is presented. • A multi-proxy approach is used to analyse growth-ring boundaries in six tropical species. • Visualization, delimitation and characterization were improved at a microscopic scale. • Our methodology opens new perspectives for dendrochronological studies in the tropics. Recent methodological advances have opened new perspectives for tropical dendrochonological studies by facilitating the visualization, delimitation, and analyses of tree-rings. One of those improvements was brought by X-ray densitometry, which allows building radial wood density profiles at microscopic scale. Furthermore, recent methods allow for cutting long histological sections to study anatomical variations along the entire radius of trees. These techniques have mainly been applied to low wood-density species from temperate and Mediterranean regions, with only limited applications in the tropics. Here we provide an improved protocol that allows for obtaining long histological sections of tropical woods, apply it to six species with varying wood densities 0.45−0.85 g cm−3 (Eucalyptus grandis , Tectona grandis , Acacia mangium , Cedrela fissilis , Hymenaea courbaril, and Copaifera duckei), and explore potential applications for tree-ring analyses. We provide instructions on core-microtome knife adjustments, procedures for softening and sectioning long histological samples of high wood-density species. We also present a multi-proxy approach that combines X-ray density profiles with the histological sections that improve the characterization and distinction of the various and complex tropical growth rings anatomical markers (fibre zone, marginal parenchyma, and ring porosity). This multi-proxy approach also opens the door for obtaining quantitative anatomy and physical parameters of tropical species with (intra-annual resolution. Our proposed approach is thus not only an additional tool to improve ring-boundary delimitation of tropical species, but it also paves the way to more innovative, borderline approaches in tropical dendrochronology. [ABSTRACT FROM AUTHOR]

• Over six years, sodium supply reduces the wood density. • The potassium and sodium supply slightly enhances the fiber length. • Sodium as a substitute for potassium leads to lower wood volume and quality. • Potassium increases stem volume without substantial losses in wood quality. • Under 37% throughfall reduction, wood density is not altered by potassium supply. In Brazil, most Eucalyptus plantations are located in regions experiencing periods of water shortage, where fertilizers such as potassium (K) are intensively used to achieve high productivity. Recently, sodium (Na) has also been considered a potential nutrient in K-deficient soils. K and Na supply can increase water stress in Eucalyptus grandis trees, which could negatively impact forest productivity over prolonged droughts. Wood properties are determinants of the quality and yield of products. They are important factors to consider when measuring the impacts of silvicultural practices and water deficit on forest productivity. However, alterations in wood properties due to interactions between K/Na fertilization, water availability, and stand age are not well documented. Through annual sampling of E. grandis trees throughout a complete rotation (6 years) in Brazil, we evaluated the interactive effects of K/Na fertilization, water availability, and stand age on stem volume, sapwood/heartwood ratio, wood density, fiber, and vessel features. We also evaluated the relationships between growth rate, wood density, and fiber and vessel features. The split-plot experimental design consisted of two water supply regimes (37% throughfall reduction versus undisturbed throughfall) and three fertilization regimes (K, Na, and control). Until six years of age, K and Na fertilization increased stem volume by 3 and 2-fold, respectively, and only K-fertilized trees affected stem volume by 37% throughfall reduction. Both K and Na detrimentally affected wood density and beneficially affected fiber length. The sapwood/heartwood ratio was highly and negatively related to the growth rate of trees. Wall thickness was not affected by either K or Na. As expected, K and Na affected vessel size due to an increase in basal area growth. However, the effects of Na were more pronounced than those of K. Significant interactions between fertilization and water availability suggest that, under water deficit, wood density will not be affected by K fertilization. In contrast, the effect of Na and control treatments were invariable regardless of water availability. The effects of fertilization on wood properties changed over time, with non-significant effects in the first year and stronger effects from two years of age of trees. The variations in wood density were strongly related to variations in the fiber wall thickness. High increases in basal area growth promoted by K and Na were not related to significant decreases in wood density, but they were related to increases in fiber length. These findings highlight the significant effects of K addition on stem volume without significant losses in wood quality, even under water stress over a complete rotation. The negative impacts observed on wood density and lower productivity in commercial E. grandis plantations with the use of Na as a substitute for K should be considered. [ABSTRACT FROM AUTHOR]

Araucaria angustifolia is an endangered species that occurs in the high and cold regions of southern Brazil. This species has economic importance due to its wood and seeds, as well as playing a fundamental ecological role for the southern fauna and flora. Climate change can affect its distributional area and conservation, making it urgent to investigate the effect of climate on its development. The objective of our study was to investigate how growth rates of A. angustifolia vary in relation to interannual precipitation, temperature, frost and snowfall events. For this purpose, we used two samples obtained from each of 33 individual trees from a forest fragment on the Santa Catarina plateau, Brazil. Classical dendrochronological methods were applied for the preparation and dating of the samples. The tree rings were measured using specialized software. Superposed Epoch analysis was used to test the snow accumulation events. The climatic variables were tested by means of a correlation analysis. The Superposed Epoch analysis was used to test the snow accumulation events. Our results indicate that the species shows significant sensitivity to the climate, with the maximum and minimum absolute temperatures respectively correlated with positive and negative growth rates. Snowfall also reduced growth of A. angustifolia. Overall, extreme cold events are threats to the conservation of the species. [ABSTRACT FROM AUTHOR]

• The wood formation appears to be more affected by growth site than rainfall reduction. • Our findings indicated that there was a difference in performance as to growth and hydraulic adjustments between eucalyptus species. • E. urophylla (A1) was productive clone with respect to volume and radial growth under water restriction. • The xylem of E. grandi s × E. camaldulensis (C3) had greater hydraulic adjustments compared to E. urophylla. The increase in global temperature results in changes in rainfall patterns and can cause structural and functional changes in trees. Each plant is forced to face hydraulic safety limits and adopt a behavior to regulate its water status. The objective of this work was to evaluate the changes in the hydraulic architecture of the xylem of commercial eucalyptus clones in order to distinguish the hydraulic adjustments in a wide gradient of water availability. Eucalyptus urophylla (A1) and E. grandis × E. camaldulensis (C3) clones at six years old at 4 sites in Brazil distributed in a rainfall gradient and in two water conditions were analyzed: control (100% of total local rainfall) and rainfall reduction (RR). Xylem traits were evaluated at annual intervals and averaged over the entire growth period of the seven trees sampled at each site and water condition. The sites influenced the clones, with the greatest effect being the rainfall reduction treatment in C3 on the vessel wall diameter, area and thickness, double wall thickness, conduction area, vessel composition index, theoretical and potential hydraulic conductivities, vessel implosion resistance and vulnerability. The rainfall reduction provided an increase of 12% in vessel density, 8% in the double vessel wall, and 27% in theoretical hydraulic conductivity in the drought-tolerant C3 clone. The vessel wall thickness in the A1 clone was more responsive with a 3% increase in rainfall reduction, with an effect on double-wall thickness and vessel implosion resistance. Other hydraulic adjustment strategies were observed, such as the highest occurrence of tylose and a tradeoff between vessel diameter and frequency for the C3 clone. The greater variation in wood density was explained by variations in the lumen area of the xylem vessels and by vessel implosion resistance. [ABSTRACT FROM AUTHOR]

Sustainable forestry requires accurate ecological information such as species composition, growth rates and recruitment dynamics. Tree growth rates are usually obtained through long-term periodic re-measurements of individual trees or through the analysis of tree growth rings in stem cross sections. However, tree growth ring analysis was traditionally thought to be only possible in biomes with strong seasonality such as those found in high latitude temperate regions. A lack of data on the occurrence and characteristics of tree rings in tropical trees may be due to a lack of investigations. Here we characterise the growth rings of 183 tree species from seven forest types across an altitudinal gradient in northern and central Perú at macro- and microscopic levels. A correspondence analysis showed an association between phylogenetic relatedness and the level of distinctiveness in the growth rings. Deciduous species of seasonally dry tropical forests were associated with distinct growth rings and mainly delimited by marginal parenchyma, while indistinct growth rings were associated with evergreen trees from lowland Amazonian and pre-montane wet forests. Additionally, for the first time the presence of growth ring boundaries defined by marginal phloem is reported in two tropical tree species, Gallesia integrifolia (Spreng.) Harms and Vochysia mapirensis Rusby. This contribution represents the most exhaustive record to date of the occurrence and anatomy of growth rings in trees of the Peruvian tropics, which can be used to inform future dendrochronological studies. [ABSTRACT FROM AUTHOR]

• There was difference between Astronium fraxinifolium trees located in impacted and non-impacted areas. • Wood anatomical features could be influenced by stress and sexual dimorphism in non-impacted areas. • Indicative that the disturbed environment exerted pressure on Astronium fraxinifolium , which expressed features in response. The survival of plants is linked to their capacity to respond to environmental selection. Plants may show different wood anatomical features related to survival, such as an increase in parenchyma and decrease in diameter of vessels. The aim of this study was to investigate the wood anatomical features of male and female Astronium fraxinifolium trees growing in environments characterized by degraded and non-degraded soil. It was expected that the trees to present: (i) a response to environment that would allow better hydraulic conductivity, and (ii) a wood anatomy difference according to the species' gender. The results showed that the wood anatomy differed significantly between male and female plants only in the non-degraded area. The male trees had larger rays and fibre lumens, but the fibre wall thickness and length did not differ significantly. Neither nor did the diameter and density of vessels. Comparing the areas, the wood of the impacted area showed vessels of larger diameter and lower density, larger rays and fibres with smaller lumens and thicker walls, but no significant difference in the fibre length. Some wood anatomical features in the impacted area, such as greater vessels, supported by larger rays and thicker fibre walls, were probably influenced by stress at the site. The anatomical features of female trees presented lower values than the male ones in the non-impacted area. [ABSTRACT FROM AUTHOR]

• Bamboo was thermo-mechanically densified using different processing parameters. • A new test apparatus was adapted to simulate an open thermo-mechanical system. • An optimization approach was used to achieve the best dimensional stability. • Densification degree, temperature, compression rate, and relaxation time were studied. Due to its reliability, strength, and ease of access, bamboo has become an attractive material for engineering applications. However, heterogeneous properties and durability issues still hinder the widespread use of bamboo as a building material. Thermo-mechanical treatment is a method to decrease the heterogeneity of bamboo culms and enhance mechanical properties and durability, but it may negatively impact dimensional stability. The objective of this study was to achieve the minimum spring back, water absorption, and thickness swelling for densified bamboo. Accordingly, the behavior of bamboo samples subjected to different thermo-mechanical (TM) treatments using a two-step analysis was investigated. In the first step, the optimum TM treatment for achieving the highest critical densification degree (DD) without shear failure was determined. In the second step, the three key elements of dimensional stability were studied for this optimum case. According to the first step results, the maximum achievable DD in which no shear failure happens and the texture is not disturbed is about 43.6%, and it can be obtained at 200 °C with a compression rate of 2 mm/min. X-ray densitometry analysis confirmed that DD of around 50% achieved the highest value of density, 1.30 g.cm−3. The results of step 2 revealed that the lowest values of spring back, water absorption, and thickness swelling, 4.72%, 23.80%, and 17.70% respectively, for densified bamboo occur when the densification process is conducted at 200 °C and adopting a compression rate of 6.7 mm/min. In conclusion, by manipulating and optimizing process parameters, the dimensional stability and final quality of densified bamboo can be improved, opening new opportunities for this class of material. [ABSTRACT FROM AUTHOR]

• Tree nutrient contents were assessed by non-destructive and quantitative XRF method. • A procedure to manufacture wood based pellets for XRF calibration is provided. • Instrumental parameters were evaluated to obtain higher sensitivity and precision. • XRF method was compared to digestion techniques used in plant nutritional studies. X-ray fluorescence spectroscopy (XRF) offers rapid, multi-elemental, low cost and non-destructive elemental analysis. Different studies have used this technique to investigate distribution and concentration of essential and deleterious elements in vegetation. Special emphasis has been recently placed on the key aspects concerning sampling processes, laboratory protocols and calibration methods for quantitative analysis. The aim of the present study was to develop a quantitative methodology to determine the nutrient content in Pinus taeda tree-rings by XRF. Using a 1 mm X-ray excitation beam from a Rh X-ray tube at 30 kV and 600 μA, and dwell time of 20 s, we present calibration curves for P, S, K, Ca, Mn and Fe based on multi-elemental standard addition using wood matrix of 17-year-old Pinus taeda trees. Satisfactory recoveries of our XRF approach for Ca, P, Mn, S and K (<115%), and tolerable for Fe (123%) were obtained compared to inductively coupled plasma optical emission spectrometry results. The non-destructive and quantitative XRF method allows assessing annual element concentrations of P. taeda trees, in order to provide tools for monitoring the nutrient dynamic in an experimental plantation. Furthermore, a method for elemental quantification based on multi-elemental standard addition using wood matrix is described as a useful procedure for future applications. [ABSTRACT FROM AUTHOR]

Highlights • Growth rings are relevant ecological indicators of historical environmental changes. • Edge effects reduced the basal area increment of the trees for at least 10 years. • Release events did not reflect higher growth of edge trees compared to interior trees. • The resumption of the common growth pattern was related to edge evolution. Abstract Although the Amazon Forest comprises the world's largest rainforest, providing fundamental ecosystem services to human well-being, vicissitudes imposed by deforestation, climate change, widespread use of fire and development of new infrastructure make the region critically vulnerable to the consequences of the creation of new forest edges. In this forest fragmentation scenario, temporal assessment of edge effects influences throughout the life of the trees become necessary for a better understanding of how species are affected and react when exposed to altered environments. In this study, we evaluated the temporal influence of the edge effect on the growth dynamics of Scleronema micranthum (Ducke) Ducke by tree-ring analysis based on basal area increment and release events. This species is one of the most frequent tree species of terra firme type of forest in Central Amazonia at the Biological Dynamics of Forest Fragment Project (BDFFP) study sites. The results showed that edge effects changed the growth dynamics of the trees for at least 10 years after the disturbance, inducing an 18% reduction in tree growth during this period, and records of increased release events. We concluded that growth rings of edge trees are a valuable bioindicators for evaluating the temporal extent of edge effects, and therefore, they must be considered as relevant ecological indicators of historical environmental changes and forest fragmentation, promoting new insights into the resilience ability of trees when exposed to forest fragmentation processes. [ABSTRACT FROM AUTHOR]

• Tree growth and wood density of C. fissilis are limited by precipitation between january and march. • Wood traits (ring width and density) were constrained by severe droughts lasting from 1 to 24 months. • Increasing water limitation during the dry season shifts growth thresholds and long-term resilience. • In the short- and long-term, the development and plasticity of the xylem are influenced by the intensity of droughts. During the last two decades the tropical Amazon forests have been impacted by frequent and severe droughts. However, little is known about the impacts of these extreme events on wood traits. In this study, we quantified long- and short-term impacts on growth and wood density response and resilience strategies under extreme droughts, analyzing the wood trait trends and correlations with climate variables (temperature, precipitation, and the SPEI drought index). Then, we simulated tree-ring formation and its responses to soil moisture using the process-based VS-Lite growth model. Our results showed how climate anomalies and dry spells increased since 1990s in the southern Amazon region and have affected the growth and wood density of C. fisillis. Ring width, latewood width and minimum wood density experienced the highest sensitivity to drought. C. fissilis showed wider (narrower) and more (less) dense rings during wetter (drier) years, respectively, suggesting that the species undergoes functional plasticity in the formation of its wood in order to adapt to dry conditions. Changes in water limitations during the dry season modify growth thresholds and long-term resilience, leading to decrease growth and increase wood density, enhancing the vulnerability of C. fissilis to projected climate warming scenarios. The short-term resilience is evidenced more in wood density than in the ring width, indicating the species' ability to adapt to short drought periods. This study is a first attempt to evidence the characteristics of the annual growth rings of C. fissilis trees in relation to climate sensitivity and resilience to drought, based on long-term data from the seasonal moist tropical forest of the Amazon. [Display omitted] [ABSTRACT FROM AUTHOR]

Modifications to a pellet manufacturing process must be made based on the characteristics of raw material used. The purpose of this work was to determine the alternations required to a wood pellet manufacturing process and the quality of the pellets produced using this process from five energy crops. Quality measurements include: the caloric value, the loss of moisture content in each production stage, the efficiency index of particle-pellet, ash content and quality as defined using the quantity of cracks and the transversal density and longitudinal density determined using X-ray radiography. The crops analyzed were rhizomatous plants, with caloric values ranging between 17.1 and 20.3 MJ kg −1 . This work determined that it was possible to produce pellets with Gynerium sagittatum and Phyllostachys aurea using the same production process for wood; however, Arundo donax and Pennisetum purpureum needed pre-air-drying and the Sorghum bicolor required mechanical dewatering before drying. A. donax , P. purpureum and G. sagittatum provided the highest efficiency index. When evaluating the pellet quality P. aurea and G. sagittatum hard a large quantity of cracks, unlike A. donax , P. purpureum and S. bicolor . The transversal and longitudinal pellet density varied from 1129 to 1294 kg m −3 . The highest values of bulk density were obtained in A. donax and P. purpureum , followed by G. sagittatum and P. aurea , and the lowest bulk density was obtained in S. bicolor . Althogh out, some species produced cracks and high ash content, this work demonstrated that it is possible to produce pellets with moderate quality. [ABSTRACT FROM AUTHOR]

• All C. multijuga trees produce oleoresin. • Non-productive trees not produce oleoresin in sufficient quantities for storage. • Productive and non-productive trees differ in anatomy only by the vessels diameter. • The heartwood area, near the pith, stands out as the location of oleoresin storage. • The oleoresin is transported from secretory canal to heartwood vessel via ray cells. The objective of this study was to identify and describe differences in the anatomical structure of productive and non-productive trees of Copaifera multijuga Hayne, and to understand the anatomical basis for production and non-production of oleoresin. We also studied how oleoresin is produced, transported and stored. The study was carried out on a primary forest area (2° 57′ 43′′ South, 59° 55′ 38′′ West) and at a 33 year-old plantation (2° 35′ 51.28′′ South and 60° 02′ 10.57′′ West), both located near Manaus, Amazonas, Brazil. A total of 27 trees were selected, including productive and non-productive trees from both areas. Wood was sampled using destructive methods (3 trees in plantations) and non-destructivly (with 2 bores from 24 trees, each giving a 5 mm radial sample). Macroscopic analysis: samples were polished until all cellular elements could be seen, then examined under a stereoscopic microscope. Microscopic analysis: Semipermanent histological sections (15 μm thick) were made in the transverse, tangential and radial longitudinal planes. Sections were also made of macerated material. In general, anatomical observations made agree with previous published studies, and show similarities to other species in the genus Copaifera. With the exception of vessel diameter, which was always higher in trees with oleoresin production (Kruskal-Wallis: p < 0.001), no qualitative or quantitative anatomical differences were observed between productive and non-productive trees. Both types of trees had oil-containing cellular elements, including the marginal parenchyma cells, rays and vessels. However, the quantity of oil-bearing cells was much higher in productive trees. Secretory canals, present in the marginal parenchyma, were mostly unobstructed (without oleoresin). However, ray cells and vessels were always filled with oleoresin, suggesting that, although oil synthesis occurs in the secretory cannals epithelial cells, its transport occurs via the ray cells to the vessels, in the heartwood region, where it is stored. [ABSTRACT FROM AUTHOR]