Variation In Wood Density Research Articles

The altitudinal distribution characteristics of functional traits reflect the resource allocation strategy of Abies georgei var. smithii in southeast Tibet

To explore the adaptation strategies of the aboveground and underground functional traits of alpine plants along an altitudinal gradient, a typical stand of primitive dark coniferous forests (Abies georgei var. smithii.) in southeastern Tibet was taken as the research object in the present study. PCA and correlation analyses were carried out for different organ functional traits (19 key indicators in total), then RDA analysis was done in conjunction with 12 environmental factors. The variation characteristics of the functional traits of leaves, current-year twigs, trunks and fine roots in 6 continuous altitude gradients and the relationships between functional traits and environmental factors were explored. The results showed that soil organic carbon (SOC) may exert a positive effect on the construction of plant defense tissue via changes in functional traits, altitude (Alt) represents the primary influencing factor of wood density (WD) variation, particulate organic carbon (POC) content mainly affected fine root dry matter (RDWC) content and specific root length (SRL), and total potassium (TK) content was the main factor that affected fine root tissue density (RTD). Leaves, current-year twigs, and fine roots exhibited high production or nutrient acquisition capacity at an altitude of 4,000m and showed strong defense and relatively stable water and nutrient transport capacity. In conclusion, the ecological strategy of Abies georgei var. smithii. in Sejila Mountain was more conservative, and the optimal survival area of Abies georgei var. smithii. was located at 4, 000m on the shady slope of Sejila Mountain. It is of paramount significance for exploring the essence of terrestrial ecosystems and their functional processes in extremely high-altitude environments.

Wood density variations of E. urophylla clone among growth sites are related to climate

The Eucalyptus genus is extensively planted in Brazil for industrial use, and with the expansion of forest frontiers and climate changes, studies are needed on how these changes affect wood density (WD). The aim of this study was to evaluate the effect of some climate variables on WD of an Eucalyptus urophylla clone for a 4–5 year period. WD from trees collected in 12 sites were evaluated. Five growth rings were identified using a magnifying glass, X-ray densitometry, and forest inventory. WD was correlated with temperature ( T), precipitation ( P), soil water deficit, ring width, and current annual increment. There was no variation in WD in the first 20 months among sites. From that age on, WD was mainly correlated with T ( r > 0.6). The 1 °C increase in T resulted in a WD reduction of 0.014 g cm−1, and increases of 10 m³ ha−1 in the final volume were related to an increase of 0.004 g cm−1 in WD. Researchers and managers should continue to put efforts into broad experimental networks to assess the effects of climate change on the adaptation and wood quality of Eucalyptus clones. Highlights The influence of climate on E. urophylla wood density was greater after the third year of growth. The mean air temperature was the best correlated climatic variable with E. urophylla wood density. The cross-site climatic gradient was more important in wood density variation of E. urophylla than the variability among the years.

Radial variation of wood density and fiber morphology of two commercial species in a tropical humid forest in Southeastern Peru

Radial variation of wood density and fiber morphology of two commercial species in a tropical humid forest in Southeastern Peru

Xylem anatomical traits determine the variation in wood density and water storage of plants in tropical semiarid climate

Wood density (WD) is a functional trait that integrates hydraulic safety and efficiency, water and carbohydrate storage, and biomechanical properties of plants. The global economic spectrum of wood shows that average WD tends to be higher in dry regions than in humid regions. In this study, we investigated the factors determining WD variation, the maximum water content in wood (WCmax), and their possibly consequences to hydraulic functioning of plants under tropical semiarid climate. Fourteen xylem anatomical traits related to mechanical support, water storage, and hydraulic efficiency and safety were measured in 39 woody species commonly found in a seasonally dry tropical forest in the Brazilian semiarid region. We tested the phylogenetic signal of all traits. The range of WD was 0.24–0.85 g cm−3 (average WD = 0.62 g cm−3). Fractions of vessel wall, fiber wall, fiber lumen, and fiber type highly influenced WD. Septate and gelatinous fibers decreased WD, whereas libriform fibers contributed to the increase in WD. Axial and radial parenchyma, fiber lumen fractions, and septate fibers presence determined WCmax variation. Xylem anatomical traits showed a weak phylogenetic signal. Wood density had a phylogenetic antisignal, indicating a functional convergence independent of phylogenetic proximity, despite species varying in their anatomical patterns. We conclude that the increase in the average WD in the analyzed species was associated with the investment in vessel wall, fiber wall fraction, and libriform fibers (mechanical support structures), which possibly increase hydraulic safety. Thus, we suggest that fiber types are important determinants of WD and WCmax and should receive more attention.

Linking wood density records of common beech (Fagus sylvatica L.) with temperature and precipitation variability from a temperate lowland site.

European lowland beech stands are under pressure by current climate change and increased drought spells. Climate sensitivity of trees is most commonly studied by examining tree-ring width records and wood density-based time series, yet the potential of the latter is underexplored for hardwoods and beech (Fagus sylvatica L.) in particular. Here, we investigate how variability in radial growth, Maximum Latewood Density (MXD) and intra-annual wood density records in lowland beech are related to monthly and daily temperature (T) and precipitation (P) records, as well as the Standardized Precipitation Evapotranspiration Index (SPEI), during the past 50 years. 45 increment cores were collected from healthy (co-) dominant beech trees in Flanders (northern Belgium). We used X-ray micro-Computed Tomography (XµCT) to obtain wood density and tree-ring width series. By dividing every tree-ring into 4 sectors of equal radial width, we also assessed climatic forcings on intra-annual wood density variability (meanQi, i = 1:4). Water availability (SPEI) is the most important factor limiting radial growth, whereas MXD is correlated with summer temperature (period May-July, r = 0.334). Scanning resolution (110, 60, 20 µm) proves to be an important parameter when interpreting MXD values. We found that to quantify climate signals at the end of the growing season, density values should be representative for a relatively large part of the latewood. Our results also suggest that a sector approach is useful by showing climatic influences during the entire growing season. Wood density at the beginning of the growing season is mainly influenced by water availability (meanQ1∼SPEI, r = 0.416), whereas towards the end of the growing season only significant correlations with temperature were observed (meanQ4∼T, r = 0.347). We recommend to further explore MXD values for hardwood trees in lowland Europe.

Multivariate drought stress response of Norway spruce, silver fir and Douglas fir along elevational gradients in Southwestern Germany

The conifer tree species Norway spruce (Picea abies), silver fir (Abies alba) and Douglas fir (Pseudotsuga menziesii) are important elements in tree species composition and forest management of Central European forests, but their potential to thrive under anticipated climatic changes is still debated controversially. This study contributes a multivariate analysis of resilience components based on increment cores sampled at breast height of Norway spruce, silver fir and Douglas fir trees growing along elevational gradients in Southwestern Germany. We aimed to gain novel insights into the species-specific and elevational response of tree growth and wood density variables during the extreme drought events of the years 2003 and 2018. Our results for Norway spruce corroborate projections of its ongoing decline during climate change as the reductions of wood density and biomass production indicated high drought sensitivity at all elevations. Moreover, resilience indices of mean tree-ring density, maximum latewood density, tree-ring width and biomass production were even lower after the drought of 2018 compared to the previous drought of 2003. Silver fir, a potential substitute tree species for Norway spruce, showed unexpected results with resistance and resilience indices being significantly lower in 2018 compared to 2003 indicating that silver fir might be more vulnerable to drought than previously expected, especially at low elevations. In contrast, the superior growth rates and higher levels of drought tolerance of Douglas fir were especially pronounced during the drought of 2018 and visible across the entire elevational gradient, even though high coning intensity was present for all investigated tree species as a possible confounding factor to exacerbate the drought stress effects in the study region.

Dendroclimatological Analysis of Chinese Fir Using a Long-Term Provenance Trial in Southern China

The Chinese fir, Cunninghamia lanceolata (Lamb.) Hook, is an essential fast-growing timber species that is widely distributed in southern China, producing timber with high economic value. Understanding the climate sensitivity of the tree species and its intra-specific variation would help us to estimate the potential climatic adaptation of the Chinese fir. Consequently, we developed radial growth (tree-ring, earlywood and latewood width) and wood density (earlywood, latewood, minimum and maximum density) chronologies for the period 1981–2013 to evaluate whether Chinese fir provenances varied in their tree-ring characteristics and the strength of their responses to seasonal and monthly climate variables. The results showed that more climatic information was obtainable from the trees’ radial growth than from their wood densities. Moreover, the wood density variables provided additional information about seasonal precipitation, which could not be found in tree-ring widths. Specifically, radial growth was highly sensitive to spring and fall temperature, whereas the wood density (particularly that of maximum density) was mainly limited by spring precipitation. Importantly, each tree-ring chronology of Chinese fir provenances varied in the intensity of its response to climate variables, reflecting population acclimation via genetic adaptation or plasticity to local conditions. By providing a theoretical basis for the climate–growth relationships of Chinese fir provenance within a subtropical climate, one can evaluate future climate change impacts on forests and the feedback of forest systems.

Variation in Growth, Wood Density, and Stem Taper Along the Stem in Self-Thinning Stands of Sassafras tzumu.

Silvicultural practices greatly improve the economic value of wood products from forests. Stem dimensions, wood density, and stem form are closely linked to end-product performance. This research aimed to examine the effects of stand density and stem height on variables that reflect ring growth and wood properties of Sassafras tzumu stands during the self-thinning phase. Between the ages of 10 and 40 years, the number of stems per hectare has declined from 1,068 to 964 due to density-dependent mortality. As the relative stand density decreased, there were significant reductions in the average tree ring width (5.07–3.51 mm) and increases in latewood proportions (49.88–53.49%) and the density of the annual growth ring (165.60–708.58 kg/m3). Therefore, ring density, earlywood density, and latewood density increased with decreasing relative stand density after self-thinning occurred. Ring width, earlywood width, and latewood width significantly increased from the base to the apex of the stem. Stand density and stem height had additive effects on S. tzumu wood properties during the self-thinning phase. A shift in the growth allocation along the longitudinal stem in response to self-thinning resulted in decreasing radial growth, increasing wood density, and improved stem form. In summary, we found a significant influence of stand density on tree ring growth, wood quality, and stem form of S. tzumu trees during the self-thinning phase.

Assessing intraspecific wood density variations of Syzgium sp. in tropical forest of Southwest Sabah

Wood density (WD) is a critical determinant of estimating forest above-ground biomass (AGB) and carbon stock. Thus, heterogeneity in WD on individuals within species trees needs to be scrutinized, and acquisition of fixed WD value is essential to estimate carbon stock with confidence. This study investigated intraspecific variation in WD of Syzgium sp., also known as “Jambu” or “Kelat”. It is the most occurring species in study areas, and is regarded as an economically important species. Firstly, one half-diameter drilling from bark-to-pith measurement was taken per tree using Rinntech Resistograph R650-ED at breast height. Meanwhile, 5.15 mm-diameter core was sampled at 1.30 m above-ground, with DeWalt DCF899HP2 20V impact wrench 950 Nm and Haglöf increment borer. WD was estimated for each core sample using a dimensional method. Drilling resistance (DR) profiles were processed using DECOM 2.38m1 Scientific (c), and several independent variables were extracted from the resistogram. All resistogram-derived variables were positively correlated with field WD (R: 0.2 – 0.70). In addition, variability on WD in Syzgium sp. population is predominantly explained by the Resistograph amplitude, expressed as mean raw scale of adjusted DR (DR adj.RawSC) in a regression model. Given that intraspecific variation in WD is a crucial conjecture in forest AGB estimation, it is recommended to analyze with larger samples, and in-depth exploration on Resistograph-based variables is deemed to improve the accuracy of WD prediction models.

Ignoring variation in wood density drives substantial bias in biomass estimates across spatial scales

Rapid development of remote sensing and Light Detection and Ranging (LiDAR) technology has refined estimates of tree architecture and extrapolation of biomass across large spatial scales. Yet, current biomass maps show significant discrepancies and mismatch to independent ground data. A potential obstacle to accurate biomass estimation is the loss of information on wood density, which can vary at local and regional scales, in the extrapolation process. Here we investigate if variation in wood specific gravity (WSG) substantially impacts the distribution of above-ground biomass (AGB) across a range of scales from local plots to large regions. We collected wood cores and measured tree volume in 341 forest sites across large altitudinal and climatic gradients in Colombia. At all spatial scales, variation in WSG was substantial compared to variation in volume. Imputing study-wide average values of WSG induced regional biases in AGB estimates of almost 30%, consequently undervaluing the difference between forest areas of low and high average wood density. Further, neither stem size nor climate usefully predicted WSG when accounting for spatial dependencies among our sampling plots. These results suggest that remote sensing- and LiDAR-based projections to biomass estimates can be considerably improved by explicitly accounting for spatial variation in WSG, necessitating further research on the spatial distribution of WSG and potential environmental predictors to advance efficient and accurate large-scale mapping of biomass.

The role of nutritional impairment in carbon‐water balance of silver fir drought‐induced dieback

Rear‐edge populations at the xeric distribution limit of tree species are particularly vulnerable to forest dieback triggered by drought. This is the case of silver fir (Abies alba) forests located in Southwestern Europe. While silver fir drought‐induced dieback patterns have been previously explored, information on the role played by nutritional impairment is lacking despite its potential interactions with tree carbon‐water balances. We performed a comparative analysis of radial growth, intrinsic water‐use efficiency (iWUE), oxygen isotopes (δ18O) and nutrient concentrations in leaves of declining (DD) and non‐declining (ND) trees in silver fir in four forests in the Spanish Pyrenees. We also evaluated the relationships among dieback predisposition, intraspecific trait variation (wood density and leaf traits) and rhizosphere soil physical–chemical properties. The onset of growth decline in DD trees occurred more than two decades ago, and they subsequently showed low growth resilience against droughts. The DD trees presented consistently lower foliar concentrations of nutrients such as P, K, Cu and Ni than ND trees. The strong effects of foliar nutrient status on growth resilience indices support the key role played by mineral nutrition in tree functioning and growth before, during and after drought. In contrast, variability in wood density and leaf morphological traits, as well as soil properties, showed weak relationships with tree nutritional status and drought performance. At the low elevation, warmer sites, DD trees showed stronger climate–growth relationships and lower δ18O than ND trees. The uncoupling between iWUE and δ18O, together with the positive correlations between P and K leaf concentrations and δ18O, point to deeper soil/bedrock water sources and vertical decoupling between nutrient and water uptake in DD trees. This study provides novel insights into the mechanisms driving silver fir dieback and highlights the need to incorporate tree nutrition into forest dieback studies.

Measuring Radial Variation in Basic Density of Pendulate Oak: Comparing Increment Core Samples with the IML Power Drill

To determine the appropriate final use of wood from a particular tree species, it is first necessary to know its properties. Methods that use wood samples taken directly from the trunk of a growing or felled tree are very time-consuming and require a great deal of manual work. Non-destructive methods may be more effective and much faster, thanks to the use of advanced technologies. The resistance drilling can be used to determine the variation in wood density along the radius of the stem. The main aim of the present study was to determine the basic density of the wood on a cross-section of the trunk of oak trees and to investigate the correlation of the results with those obtained by drilling the same trees with the IML RESI-PD 400. The results of Spearman’s correlation test showed strong positive correlations between all examined properties. We observed a trend whereby the density of the wood and Resi amplitude increased in direct proportion to the width of the annual rings. The results of linear regression show a strong relationship between examined properties. This study provide evidence that the Resi is an appropriate tool for non-destructive determination of wood density.

Variation in Wood Density and Mechanical Properties of Acacia mangium Provenances Planted in Vietnam

ABSTRACT There is a growing interest in improving wood properties through the appropriate selection of seed provenances within species. In this study, wood density and mechanical properties were investigated for Acacia mangium trees from six different provenances, planted in Quang Tri, Vietnam. Radial and among provenance variation in stress wave velocity (SWV), wood density (WD), dynamic modulus of elasticity (MOEd), modulus of rupture (MOR), and modulus of elasticity (MOE) were determined on a total of 480 small clear specimens (20 × 20 × 300 mm) cut from 30 trees (five per provenance). SWV and selected wood properties near the pith were significantly lower than those near the bark. Differences in all selected mechanical properties among provenances were significant. The highest static properties (MOR and MOE) were found for the Long Thanh provenance indicating its potential suitability for breeding programs in Vietnam focused on improving A. mangium wood quality. A high positive correlation coefficient was found between MOEd and MOE (r = 0.93, P < 0.001) and our results indicate that the stiffness of A. mangium can be predicted using stress wave method provided the density of measured element is known.

Assessing the Dependencies of Scots Pine (Pinus sylvestris L.) Structural Characteristics and Internal Wood Property Variation

Wood density is well known to vary between tree species as well as within and between trees of a certain species depending on the growing environment causing uncertainties in forest biomass and carbon storage estimation. This has created a need to develop novel methodologies to obtain wood density information over multiple tree communities, landscapes, and ecoregions. Therefore, the aim of this study was to evaluate the dependencies between structural characteristics of Scots pine (Pinus sylvestris L.) tree communities and internal wood property (i.e., mean wood density and ring width) variations at breast height. Terrestrial laser scanning was used to derive the structural characteristics of even-aged Scots pine dominated forests with varying silvicultural treatments. Pearson’s correlations and linear mixed effect models were used to evaluate the interactions. The results show that varying silvicultural treatments did not have a statistically significant effect on the mean wood density. A notably stronger effect was observed between the structural characteristics and the mean ring width within varying treatments. It can be concluded that single time terrestrial laser scanning is capable of capturing the variability of structural characteristics and their interactions with mean ring width within different silvicultural treatments but not the variation of mean wood density.

The legacy of the extinct Neotropical megafauna on plants and biomes

Large mammal herbivores are important drivers of plant evolution and vegetation patterns, but the extent to which plant trait and ecosystem geography currently reflect the historical distribution of extinct megafauna is unknown. We address this question for South and Central America (Neotropical biogeographic realm) by compiling data on plant defence traits, climate, soil, and fire, as well as on the historical distribution of extinct megafauna and extant mammal herbivores. We show that historical mammal herbivory, especially by extinct megafauna, and soil fertility explain substantial variability in wood density, leaf size, spines and latex. We also identified three distinct regions (‘‘antiherbiomes’’), differing in plant defences, environmental conditions, and megafauna history. These patterns largely matched those observed in African ecosystems, where abundant megafauna still roams, and suggest that some ecoregions experienced savanna-to-forest shifts following megafauna extinctions. Here, we show that extinct megafauna left a significant imprint on current ecosystem biogeography.

Wood Density and Ring Width in Quercus rotundifolia Trees in Southern Portugal

Quercus rotundifolia Lam., known as holm oak or evergreen oak, occurs naturally in the western Mediterranean region, mainly as part of the agroforestry or agrosilvopastoral systems in Portugal (“montado”) and Spain (“dehesa”), and is economically important for acorn production. Less attention has been given to Q. rotundifolia wood, and its density variability is not known, namely related to tree growth. The wood density of 20 Q. rotundifolia trees was measured along the radial direction by X-ray densitometry and the factors responsible for ring width and wood density variation within and between trees were investigated at two sites located within the main species region in southern Portugal. Ring width was significantly different between sites, with an average of 1.81 mm and 1.55 mm. Wood density was very high and averaged between 888 kg/m3 and 914 kg/m3 but not significantly different between sites. Ring width and wood density showed a positive and significant correlation at both sites. Cambial age was the main source of variation for ring width and wood density, while between-tree effects accounted for a considerable proportion of wood density variation. The results are an important contribution for the species valorisation aiming at high-value wood products, also adding knowledge on the species growth of interest for tree selection and sustainable management.

Genetic influence on components of wood density variation in white spruce

Abstract Conifer breeding programmes are increasingly selecting for wood quality in addition to growth so to ensure a sufficient flow of high-quality fibre from future forest plantations. As wood density is one of the most frequently used indicators of wood quality, there is a growing interest to consider this trait in selection, and thus enhance the properties of end-use products from planted trees. However, wood density varies at different scales within trees, with pith-to-bark patterns and year-to-year fluctuations representing two important sources of variation. From both physiological and end-use points of view, it is desirable to produce stems with limited pith-to-bark and year-to-year wood density variation. In the present study, we assessed patterns of pith-to-bark and year-to-year variation in 2196 wood density patterns and evaluated the genetic control of traits characterizing this variation. The experimental data came from a 15-year-old white spruce genetic trial representing 93 full-sib families replicated in two contrasting environments in Quebec, Canada. To separate pith-to-bark from year-to-year variation, non-linear models were developed to describe pith-to-bark patterns of variation in the mean ring density (MRD) of individual trees as well as for latewood density (LWD) and latewood proportion. We observed that pith-to-bark variation was more under genetic control than year-to-year variation, for which only LWD and proportion of latewood width to overall ring width reached moderate genetic control. Little genotype-by-environment interaction was observed although wood density patterns differed significantly between sites. The present approach could help identify trees or families that tend to have limited pith-to-bark and year-to-year variation in wood density as part of tree genetic improvement programmes to provide future trees with more uniform and desirable wood attributes.

Interspecific variations in mangrove stem biomass: A potential storehouse of sequestered carbon

Variations in stem biomass and carbon density in 12 mangrove species were studied to understand the potential of carbon storage in the live biomass of Bhitarkanika mangrove ecosystems, South-East Coast of India. The results highlighted significant inter-species variations (p<0.01; ANOVA) in the stem wood density and carbon content and could be attributed to the spatial variations in soil fertility, adaptation, freshwater supply, genus identity as well as properties of the fibre lumen and wall. Among the studied species, Avicennia officinalis showed the highest carbon density and Corg/Ntot ratios followed by Heritiera fomes. Further, the higher carbon sequestration capacity of these two mangrove species was confirmed through Principal Component Analysis (PCA). Corg, Corg/Ntot and cellulose/protein ratio were strongly associated with the wood density of the studied mangrove species. Mangrove stem diameter (at breast height; DBH), wood density and tree height were used to estimate the above-ground biomass of all the species, which showed remarkably higher biomass for Avicennia officinalis. Possible adaptation of these species under extreme environmental conditions in addition to variations in vessel wall thickness caused by differential carbon fixation and storage in the form of biomass could explain the variability in elemental properties of mangrove stem wood. Heritiera littoralis and Kandelia candel with relatively higher lignin to cellulose content showed greater potentials to sustain biotic and abiotic stresses and indicated higher carbon sequestration as recalcitrant biomass. The lowest carbon density and highest ratio of cellulose/lignin in the Sonneratia apetala and Sonneratia caseolaris species indicated faster plant growth compared to the other studied species. FTIR analysis evidenced that the increase in the 1728–1733 cm −1 band height assigned to cellulose and decrease in the 1517–1519 cm −1 band height assigned to lignin.

Anatomical properties of Hibiscus macrophyllus and its mature wood development

Abstract The Hibiscus macrophyllus tree is widely planted in Indonesia especially on Java Island. It has several advantages to be developed commercially as a community or plantation forest compared to the famous introduced species Falcataria moluccana and Anthocephalus spp., including faster growth, higher wood density, and better stem morphology (straighter, more rounded, and lesser branches). However, information about the basic properties of this wood grown in plantations is limited. This study aimed to investigate the anatomical properties of H. macrophyllus and their variation at three ages (8, 12 and 16 years old), as well as to predict the mature wood development by using radial variation in fiber length, microfibril angle (MFA), and wood density from pith toward the bark as the indicators. The wood samples were obtained from a community forest area at Ciamis Regency, West Java Province. Furthermore, anatomical characteristics were examined through wood slides following the IAWA List, while fibre and vessel element dimensions were measured through macerated specimens prepared by modified Franklin’s method. The MFA was determined by X-Ray Diffraction, while wood density was measured in line with British Standard 373-57. The results showed that the anatomical structures were not influenced by tree age, except for wood porosity, and fibre and vessel element dimensions. The 16-year-old tree tended to be semi-ring-porous, the younger trees were diffuse-porous, while the fiber and vessel element length, as well as the diameter, were decreased. Meanwhile, the wall thickness was increased. The fibre length, MFA, and wood density were useful indicators for wood maturity that seemed to be developed at about 11 years of age.

Sources of phenotypic variation of wood density and relationships with mean growth in two Eucalyptus species in Argentina

Aims of the study: To describe the radial patterns of wood density, and to identify their main sources of variation, and the potential tradeoffs with mean tree growth, in two Eucalyptus species. Area of study: Mesopotamian (Corrientes and Entre Ríos provinces) and Pampean region (Buenos Aires province) of Argentina. Materials and methods: Eucalyptus grandis and Eucalyptus viminalis, growing in genetic trials installed in two sites per species were studied. X-ray wood microdensity profiles were developed from core samples. Each profile was proportionally divided in 10 sections. Mean, maximum, minimum and the standard deviation of wood density, for each section were computed. Mean annual growth was used to study the relationships with wood microdensity variables. A linear mixed-effects model computed the significance of different sources of phenotypic variation. Pearson´s correlation computed the relationships between variables. Main results: The pattern of radial variation in E. grandis showed a decrease in wood density from pith to bark, mainly due to the decrease in minimum wood density, while in E. viminalis, wood density increased towards the outer wood. In both species, the standard deviation of the wood density increased along the radial profile from pith to bark. Significant variation in wood density was explained by site, provenance and clone/family effects. In E. grandis mean, maximum and minimum wood density were negatively correlated with mean growth, whereas in E. viminalis correlations were positive but close to zero. Research highlights: Both the pattern of radial variation of wood density and the relationship between wood density and mean growth were different in the studied Eucalyptus species, and they varied within species depending on the site they were growing and genetic provenance. Keywords: wood microdensity profile; wood properties; wood products; phenotypic plasticity; Eucalyptus grandis; Eucalyptus viminalis.