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Abstract Mechanical properties of wood–plastic composites are influenced by a particle size and surface morphology of wood flour. Generally various sizes of wood flour are produced from single solid wood even if the single process is used. If the different particle size of wood flour is produced from different wood tissue such as earlywood (EW) and latewood (LW), not only particle size but also density and chemical composition of wood flour might influence the mechanical property of final products. This study aims to investigate the relationship between particle size and their origin; EW and LW. EW and LW were separately milled to produce the EW and LW flour by dry and wet milling. Hyperspectral images ranging 400–1000 nm for each wood flour were used as training data. Discriminant model of EW and LW flour developed by PLS-DA showed over 0.77 of accuracy. Then the EW and LW were dry and wet milled together and screened by three different sieve openings to obtain different particle size wood flour. Discriminant model was applied for the hyperspectral images of each size of wood flour to estimate the EW and LW ratio. The result showed that increasing sieve opening resulted in the increasing ratio of LW for dry milled wood flours. The results suggest that the EW was easily pulverized than LW.

Mechanical properties of wood–plastic composites are influenced by a particle size and surface morphology of wood flour. Generally various sizes of wood flour are produced from single solid wood even if the single process is used. If the different particle size of wood flour is produced from different wood tissue such as earlywood (EW) and latewood (LW), not only particle size but also density and chemical composition of wood flour might influence the mechanical property of final products. This study aims to investigate the relationship between particle size and their origin; EW and LW. EW and LW were separately milled to produce the EW and LW flour by dry and wet milling. Hyperspectral images ranging 400–1000 nm for each wood flour were used as training data. Discriminant model of EW and LW flour developed by PLS-DA showed over 0.77 of accuracy. Then the EW and LW were dry and wet milled together and screened by three different sieve openings to obtain different particle size wood flour. Discriminant model was applied for the hyperspectral images of each size of wood flour to estimate the EW and LW ratio. The result showed that increasing sieve opening resulted in the increasing ratio of LW for dry milled wood flours. The results suggest that the EW was easily pulverized than LW. [ABSTRACT FROM AUTHOR]

The tensile mechanical behavior of water-saturated earlywood (EW) and latewood (LW) within the same growth ring of Masson pine (Pinus massoniana) was investigated in the hydrothermal environment and discussed with respect to the density and microfibril angle (MFA) of the wood specimens. The tensile modulus, tensile strength, and strain at failure of EW and LW in the longitudinal (L) and tangential (T) directions were determined at different temperature levels ranging from 30 °C to 80 °C. Major differences in the tensile mechanical properties were found between EW and LW in the L and T directions. Compared to LW, EW showed a smaller density and a larger MFA, resulting in a lower tensile modulus, lower tensile strength, and higher strain at failure. Compared to the L specimens, the T specimens showed lower tensile modulus, lower tensile strength, and higher strain at failure. As the hygrothermal temperature increased, the MFAs, tensile modulus, and tensile strength of EW and LW specimens decreased, except for the MFAs of LW, while the strain at failure of the specimens showed the opposite trend. Variations in the tensile mechanical behavior between EW and LW were mainly influenced by the density and MFA of the specimens, and are closely associated with the hydrothermal softening properties of wood. These findings contribute to a further understanding of the structural–mechanical relationships of Masson pine wood at the cell wall level, and provide a scientific basis for the better utilization of plantation softwood in the hydrothermal environment. [ABSTRACT FROM AUTHOR]

To reveal the response degree of ring width for earlywood, latewood, and ringwood of Larix olgensis plantation to climate change, 135 sample trees from 27 sample plots in Maoershan Experimental Forest Farm of Northeast Forestry University were taken as data sources, based on the establishment of tree ring chronology, the correlation analysis was used to quantify the relationship between ring width earlywood, latewood, and ringwood and climate factors. Results showed that the ring width of L. olgensis can be divided into two distinct time periods on the time scale. During 1974-1985, the tree growth was mainly affected by the temperature in spring and autumn, while from 1986 to 2019, it was mainly affected by the temperature in summer. During 1974-1985, the highest and lowest temperaturesin winter and spring, especially in January, February, April and May of the previous year and that year, had a negative correlation (P<0. 05) with the growth of earlywood and ringwood, but a positive correlation with the growth of latewood (P<0. 05). The period in April and May of the previous year and the spring of that year had a negative correlation with the growth of ring width of earlywood (P<0. 05). From 1986 to 2019, the highest and lowest temperatures in summer, especially in June and July of the previous year and that year, had a significant positive correlation with the ring width of latewood (P<0. 05). The average temperature in summer, especially in July of the previous year and that year, had a significant positive correlation with the growth of latewood (P<0. 05), but a significant negative correlation with the growth of ring width of earlywood and ringwood (P<0. 05). On the whole, the temperature in the growing season, especially the minimum temperature and average temperature, are the main factors limiting the growth of earlywood and latewood of L. olgensis plantation, the effect of precipitation on the growth ofearlywood and latewood is not significant. [ABSTRACT FROM AUTHOR]

Abstract Key message We elucidated the age trends of narrow-sense heritability and phenotypic/genetic correlations and the age–age genetic correlation of growth ring components of Cryptomeria japonica D. Don by investigating progenies of controlled crossings by soft X-ray densitometry analysis. Wood density in the C. japonica breeding program can be efficiently improved by selecting trees with a higher earlywood density and latewood percentage as early as forest stand ages of 5–9 years. Context Wood density within the trunk is affected by the intra-ring wood density profile and its age trend from pith to bark. Wood density can be efficiently improved by clarifying whether wood density and highly correlated intra-ring components are under additive genetic control. Aims The aim of this study was to elucidate the age trends of narrow-sense heritability and phenotypic/genetic correlations of growth ring components and investigate the possibility of early selection for improving wood density in Cryptomeria japonica. Methods We quantified seven growth ring components (width, density, earlywood/latewood width, average earlywood/latewood density, and latewood percentage) for 5112 annual rings of 342 18-year-old trees derived from 24 controlled pollinated full-sib families of C. japonica plus tree clones by soft X-ray densitometry analysis. Genetic parameters and correlations among the seven growth ring components were analyzed using a linear mixed model and the breedR package. Results Earlywood density and latewood percentage exhibited a higher phenotypic and genetic correlation with ring density than the other ring components at almost all ages. Earlywood density and latewood percentage exhibited a lower correlation with ring width than the other ring components after a stand age of 5 years. The age–age genetic correlation of earlywood density and latewood percentage was 0.70 for a stand age of 17 years and was strong at stand ages of 5 and 9 years. Conclusion Efforts focusing on improving earlywood density and latewood percentage may contribute to improving wood density efficiently in tree breeding programs for C. japonica. Traits related to the ring density of C. japonica trees can possibly be selected as early as stand ages of 5–9 years, and the required period for progeny selection may be substantially shortened when selecting trees with high wood density.

Key message: We elucidated the age trends of narrow-sense heritability and phenotypic/genetic correlations and the age–age genetic correlation of growth ring components of Cryptomeria japonica D. Don by investigating progenies of controlled crossings by soft X-ray densitometry analysis. Wood density in the C. japonica breeding program can be efficiently improved by selecting trees with a higher earlywood density and latewood percentage as early as forest stand ages of 5–9 years. Context: Wood density within the trunk is affected by the intra-ring wood density profile and its age trend from pith to bark. Wood density can be efficiently improved by clarifying whether wood density and highly correlated intra-ring components are under additive genetic control. Aims: The aim of this study was to elucidate the age trends of narrow-sense heritability and phenotypic/genetic correlations of growth ring components and investigate the possibility of early selection for improving wood density in Cryptomeria japonica. Methods: We quantified seven growth ring components (width, density, earlywood/latewood width, average earlywood/latewood density, and latewood percentage) for 5112 annual rings of 342 18-year-old trees derived from 24 controlled pollinated full-sib families of C. japonica plus tree clones by soft X-ray densitometry analysis. Genetic parameters and correlations among the seven growth ring components were analyzed using a linear mixed model and the breedR package. Results: Earlywood density and latewood percentage exhibited a higher phenotypic and genetic correlation with ring density than the other ring components at almost all ages. Earlywood density and latewood percentage exhibited a lower correlation with ring width than the other ring components after a stand age of 5 years. The age–age genetic correlation of earlywood density and latewood percentage was 0.70 for a stand age of 17 years and was strong at stand ages of 5 and 9 years. Conclusion: Efforts focusing on improving earlywood density and latewood percentage may contribute to improving wood density efficiently in tree breeding programs for C. japonica. Traits related to the ring density of C. japonica trees can possibly be selected as early as stand ages of 5–9 years, and the required period for progeny selection may be substantially shortened when selecting trees with high wood density. [ABSTRACT FROM AUTHOR]

Scots pine (Pinus sylvestris L.) is an evergreen coniferous tree with wide distribution and good growth performance in a range of habitats. Therefore, wood from P. sylvestris is produced in many managed forests and is frequently used in industry. Despite the importance of pine wood, we still do not fully understand its molecular structure what limits improvements in its processing. One of the basic features leading to variation in wood properties is the presence of earlywood and latewood which form annual growth rings. Here, we characterise biochemical traits that differentiate cell walls of earlywood and latewood in Scots pine. We discover that latewood is less recalcitrant to enzymatic digestion, with galactoglucomannan showing particularly pronounced difference in accessibility. Interestingly, characterisation of lignin reveals a higher proportion of coniferaldehydes in pine latewood and suggests the presence of a different linkage landscape in this wood type. With complementary analysis of wood polysaccharides this enabled us to propose the first detailed molecular model of earlywood and latewood and to conclude that the variation in lignin structure is likely the main determinant of differences in recalcitrance observed between the two wood types in pine. Our discoveries lay the foundation for improvements in industrial processes that use pine wood since we show clear pathways for increasing the efficiency of enzymatic processing of this renewable material. Our work will help guide future breeding of pine trees with desired timber properties and can help link molecular structure of softwood cell walls to function of the different types of xylem in conifers. [ABSTRACT FROM AUTHOR]

Abstract Dynamic mechanical analysis (DMA) measurements of water-saturated earlywood (EW) and latewood (LW) of various wood species in the temperature range from 0 to 100 °C were focused to clarify the differences in thermal softening properties within an annual ring. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in both EW and LW all species. For softwoods, the peak temperatures of tanδ of EW appeared at higher temperatures than those of LW. For hardwoods, in the other hand, the peak temperatures of tanδ were slightly different between EW and LW in the diffuse-porous wood, whereas the temperatures were almost the same in the ring-porous wood. It was found that the difference in peak temperature of tanδ between EW and LW varied greatly among species. The difference in peak temperature between EW and LW was relatively large for softwoods. In addition, the thermal softening properties both in the radial and tangential directions differed depending on the species, so this suggested that there was anisotropy in the thermal softening properties depending on the species.

Scots pine (Pinus sylvestris L.) is an evergreen coniferous tree with wide distribution and good growth performance in a range of habitats. Therefore, wood from P. sylvestris is produced in many managed forests and is frequently used in industry. Despite the importance of pine wood, we still do not fully understand its molecular structure what limits improvements in its processing. One of the basic features leading to variation in wood properties is the presence of earlywood and latewood which form annual growth rings. Here, we characterise biochemical traits that differentiate cell walls of earlywood and latewood in Scots pine. We discover that latewood is less recalcitrant to enzymatic digestion, with galactoglucomannan showing particularly pronounced difference in accessibility. Interestingly, characterisation of lignin reveals a higher proportion of coniferaldehydes in pine latewood and suggests the presence of a different linkage landscape in this wood type. With complementary analysis of wood polysaccharides this enabled us to propose the first detailed molecular model of earlywood and latewood and to conclude that the variation in lignin structure is likely the main determinant of differences in recalcitrance observed between the two wood types in pine. Our discoveries lay the foundation for improvements in industrial processes that use pine wood since we show clear pathways for increasing the efficiency of enzymatic processing of this renewable material. Our work will help guide future breeding of pine trees with desired timber properties and can help link molecular structure of softwood cell walls to function of the different types of xylem in conifers.

Intra-annual density fluctuation (IADF) refers to anatomical changes in the tree ring caused by a sudden change in wood density triggered by a combination of climate variations and various biotic and abiotic influences. To reveal the occurrence of IADFs, we analyze the growth rings of Himalayan cedar (Cedrus deodara) growing over the Kullu region, Himachal Pradesh, western Himalaya. Using 30 increment cores, we precisely dated and developed a 214-year-long tree-ring chronology extending back to AD 1808. The tree–growth–climate relationship using ring-width chronology and observed climate data revealed that cool and moist condition provides favorable condition for Himalayan cedar tree growth. Delving deeper into wood anatomy of growth rings, we revealed the frequent occurrences of IADFs in both earlywood (IADFe) and latewood (IADFl). The formation of IADFs in earlywood (IADFe) is related to the reduced precipitation from April to July, causing moisture stress in the soil and surrounding climate. However, wetter conditions in the late growing season, mainly August–October, activated the formation of IADFs in latewood (IADFl). The study revealed several IADF years in earlywood and latewood, such as 1901, 1902, 1903, 1914, 1915, 1919, 1920, 1923, 1925, 1943, 1958, 1959 and 1937, 1955, 1956, 1988, respectively. These IADF years corresponded with unusual climatic fluctuations that severely affected apple production, the major cash crop in the region. The analyses demonstrated that the IADF chronology of Himalayan cedar would be a valuable proxy to understand abrupt and unusual climatic fluctuations from a long-term perspective for the data-scarce western Himalayan region.

The quantitative description of growth rings is yet incomplete, including the functional division into earlywood and latewood. Methods developed to date, such as the Mork criterion for conifers, can be biased and arbitrary depending on species and growth conditions. We proposed the use of modeling of the statistical distribution of tracheids to determine a universal criterion applicable to all conifer species. Thisstudy was based on 50-year anatomical measurements of Pinus sylvestris L., Pinus sibirica Du Tour, and Picea obovata Ledeb. near the upper tree line in the Western Sayan Mountains (South Siberia). Statistical distributions of the cell wall thickness (CWT)-to-radial-diameter (D) ratio and its slope were investigated for raw and standardized data (divided by the mean). The bimodal distribution of the slope for standardized CWT and D was modeled with beta distributions for earlywood and latewood tracheids and a generalized normal distribution for transition wood to account for the gradual shift in cell traits. The modelcan describe with high accuracy the growth ring structure for species characterized by various proportions of latewood, histometric traits, and gradual or abrupt transition. The proportion of two (or three, including transition wood) zones in the modeled distribution is proposed as a desired criterion. [ABSTRACT FROM AUTHOR]

Dynamic mechanical analysis (DMA) measurements of water-saturated earlywood (EW) and latewood (LW) of various wood species in the temperature range from 0 to 100 °C were focused to clarify the differences in thermal softening properties within an annual ring. The following results were obtained. The peak of tanδ caused by micro-Brownian motion of lignin was observed in both EW and LW all species. For softwoods, the peak temperatures of tanδ of EW appeared at higher temperatures than those of LW. For hardwoods, in the other hand, the peak temperatures of tanδ were slightly different between EW and LW in the diffuse-porous wood, whereas the temperatures were almost the same in the ring-porous wood. It was found that the difference in peak temperature of tanδ between EW and LW varied greatly among species. The difference in peak temperature between EW and LW was relatively large for softwoods. In addition, the thermal softening properties both in the radial and tangential directions differed depending on the species, so this suggested that there was anisotropy in the thermal softening properties depending on the species. [ABSTRACT FROM AUTHOR]

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Black pine (Pinus nigra) is a widely distributed tree species across southern Europe and Asia Minor. This article summarizes a dendroclimatological study of subannual P. nigra ring width conducted during an international summer course "Tree Rings, Climate, Natural Resources, and Human Interaction" in 2022. Increment cores were collected from 15 young (oldest 105 years) P. nigra trees in the Araç Forest District inKastamonu Province, Turkey. Site chronologies of earlywood (EW) and latewood (LW) width were developed to investigate climatic signals using correlation analysis. Results show thatEWand LW chronologies are significantly correlated with one another (r = 0.56, n = 105, p < 0.001) and positively correlated with precipitation in the months April-September of the growth year. The month of strongest correlation shifts from April for EW to July for LW. Analysis of seasonally aggregated climate data further shows that EW but not LW responds positively to precipitation in the preceding summer (July-September). These results suggest that future tree-ring studies aimed at tree-growth impact of climate change in the Black Sea region of Turkey exploit the climate signal in subannual ring widths of P. nigra. [ABSTRACT FROM AUTHOR]

Our understanding of land‐based cool season temperature variability over the past millennium is limited by the relative lack of annually resolved temperature proxies, especially in the Southern Hemisphere. Here, we develop the first earlywood (EW) and latewood (LW) width chronologies from Australia based on the Tasmanian endemic conifer Athrotaxis selaginoides in the far southeast of Australia. We also develop total ring width (RW), EW and LW chronologies from a new site in the far south. We compare the climate responses of RW, EW and adjusted LW chronologies of three A. selagnoides sites near the southern extent of the species with three sites of the species near the northern extent of the species. RW and EW at the southern sites are strongly and positively related to cool season temperature (July–October), but in the north, RW and EW are more strongly and positively related with summer (December–February) temperatures. Once adjusted for the influence of the same growing season EW, LW in the north is very strongly negatively correlated with January–February temperatures across southeastern Australia. The new southern RW and EW chronologies can be used to extend one of only two annually resolved regional cool season temperature reconstructions in the Southern Hemisphere back a further 180 years. [ABSTRACT FROM AUTHOR]

The tensile mechanical behavior of water-saturated earlywood (EW) and latewood (LW) within the same growth ring of Masson pine (Pinus massoniana) was investigated in the hydrothermal environment and discussed with respect to the density and microfibril angle (MFA) of the wood specimens. The tensile modulus, tensile strength, and strain at failure of EW and LW in the longitudinal (L) and tangential (T) directions were determined at different temperature levels ranging from 30 °C to 80 °C. Major differences in the tensile mechanical properties were found between EW and LW in the L and T directions. Compared to LW, EW showed a smaller density and a larger MFA, resulting in a lower tensile modulus, lower tensile strength, and higher strain at failure. Compared to the L specimens, the T specimens showed lower tensile modulus, lower tensile strength, and higher strain at failure. As the hygrothermal temperature increased, the MFAs, tensile modulus, and tensile strength of EW and LW specimens decreased, except for the MFAs of LW, while the strain at failure of the specimens showed the opposite trend. Variations in the tensile mechanical behavior between EW and LW were mainly influenced by the density and MFA of the specimens, and are closely associated with the hydrothermal softening properties of wood. These findings contribute to a further understanding of the structural–mechanical relationships of Masson pine wood at the cell wall level, and provide a scientific basis for the better utilization of plantation softwood in the hydrothermal environment.

Thermal modification can increase the physical stability and impact the mechanical strength of wood. It is necessary to understand the effects of modifications on the compressive stress of wood. In this study, Douglas fir (Pseudotsuga menziessi) blocks were modified at 180 °C (TM-180 °C) and 210 °C (TM-210 °C). The compressive stress of pure earlywood (EW), pure latewood (LW), and combined earlywood and latewood (ELW) specimens was measured. The specimens were compressed at 30% of their original thickness, and during the compression test the strain distribution of the ELW was recorded. In addition, the microstructures before and after compression were investigated, complemented with SEM to understand the structural changes taking place. The results showed that the compressive stress of the TM-180 °C specimens was the highest because the thermal modification increased the stiffness of cell walls and the homogenized strain distribution in the ELW specimens. The control specimens had a higher compression set recovery rate than the thermally modified specimens. The tracheid cell walls in the EW and LW specimens were flattened and buckled, respectively, due to compression. In the thermally modified materials, cell wall fissures and wood ray fractures in the EW and LW specimens, respectively, were observed. For the ELW specimens, the structural changes in the latewood were not obvious and the structural changes in the earlywood were less significant than in the full EW specimens. Compared to the EW specimens, the earlywood in the ELW specimens showed higher compression set recovery rates. It seems that structural failure in earlywood is limited when used in combination with latewood, resulting from the homogenized strain distribution in earlywood. [ABSTRACT FROM AUTHOR]

Furfurylated wood has many advantages, such as decay resistance, dimensional stability, hardness, etc. However, furfurylation increases the brittleness and decreases the flexural resistance of wood, which greatly limits its application. Therefore, caprolactam (CPL) is incorporated with furfuryl alcohol (FA) to improve the performance of furfurylated wood. In this study, an FA and CPL combinational modifier was used to treat masson pine (Pinus massoniana Lamb.) earlywood and latewood. The synergistic interaction of both components with the wood cell walls was systematically evaluated via microstructural, chemical, and thermal analysis using scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometry (XPS), and differential scanning calorimetry (DSC). The SEM images showed that polymerized modifiers were distributed in tracheids, ray cells, and pits, with a higher degree of distribution in latewood tissues. The FA-CPL co-treatment led to the highest degree of distribution in cell cavities as well as of cell wall swelling. The results of the weight percentage gain (WPG) of modified wood agreed with the SEM findings that the FA-CPL co-treatment could more effectively increase the WPG than individual modification. The results of FTIR and XPS revealed that FA and CPL might chemically bind with each other as well as react with lignin and hemicellulose in the cell walls during the curing process. In addition, the interactions between modifiers and cell walls were slightly different for earlywood and latewood. DSC analysis indicated that the wood hygroscopicity decreased and the thermal stability improved after modification. [ABSTRACT FROM AUTHOR]

This study investigated the variations in tracheid length of Pseudotsuga menziesii (Mirb.) Franco from three sites in Croatia in relation to cambium age, within- and between-site differences, and growth rate. Tracheids are the main structural element in P. menziesii wood, varying in length following different patterns that should be precisely determined. After the maceration procedure, earlywood tracheid length (EWTL), latewood tracheid length (LWTL), annual growth ring tracheid length (RTL), earlywood ring width (EWW), latewood ring width (LWW), and annual ring width (ARW) were measured in selected annual growth rings. The significant effect of annual growth rings and zone interaction for EWTL and LWTL, as well as of annual growth rings, trees, and sites for RTL, was determined. The results conclude on the differences between the trends in EWTL and LWTL from pith toward the bark. In addition, the correlation analysis between the tracheid length and different growth patterns was investigated, and very weak or no association between the variables was detected. This research contributes to better understanding the degree of wood uniformity of P. menziesii from the technological perspective, as well as the variability factor in the optimization of forest management with favoring overall wood quality. [ABSTRACT FROM AUTHOR]

Abstract Dynamic mechanical analysis (DMA) and small angle X-ray scattering (SAXS) measurements of water-saturated wood of Douglas fir (Pseudotsuga menziesii) in the temperature range of 0 ℃ to 100 ℃ were focused to clarify microstructural changes within an annual ring. The following results were obtained. Thermal softening behavior caused by micro-Brownian motion of lignin was observed in both earlywood and latewood. The peaks of tanδ were found at around 95 ℃ for earlywood and at around 90 ℃ for latewood. These results suggested that the structures of lignin in the cell wall were different between earlywood and latewood. SAXS measurements of water-saturated earlywood and latewood in water were performed with precise temperature control. The scattering intensity increased with increasing temperature, indicating that the density of the matrix was reduced at higher temperature. One-dimensional SAXS intensity at the equator, which approximately represents cellulose microfibrils arrangement in the matrix, was intensively analyzed using the WoodSAS model. The result of this model fitting showed that the cellulose microfibril diameter of latewood was higher than that of earlywood. In addition, the value of interfibrillar distance decreased monotonically in the earlywood, while it decreased rapidly in the latewood from 60 ℃ to 90 ℃. The changes in the cellulose microfibril (CMF) diameter and the interfibrillar distance with increasing temperature between earlywood and latewood by SAXS measurement were different. The differences in CMF diameter and inter-fibril distance between earlywood and latewood measured by SAXS also support the hypothesis that lignin structure differs between earlywood and latewood based on the results of DMA measurements.

The increase in the atmospheric carbon dioxide concentration promotes its accumulation in trees by regulating the synthesis and transportation genes for endogenous hormones, such as IAA and GA, which are key factors in regulating various life activities, including growth rings. To explore the impact of changes in endogenous hormone levels such as IAA and GA on the growth of tree rings, and to provide a basis for improving the management of hybrid larch clonal forests, we investigated the effects of exogenous indole-3-acetic acid (IAA), gibberellic acid 3 (GA3), and their combination on tree-ring growth in hybrid larch. IAA, GA3, and a combination treatment were sprayed on the leaves of one clone of a hybrid larch seedling every three days. Small blocks were collected at the base stems for sequential anatomical observations. The phytohormone type, instead of the concentration, had a more significant effect on wood formation. Specifically, IAA treatment at 300 mg L−1 significantly increased latewood (LW) layers until 90 days after treatment (DAT). The 500 mg L−1 treatment significantly increased the wall radial thickness (WRT) of latewood (LW) cells. GA3 treatment at 100 mg L−1 significantly decreased the layers and width of total wood (TW), LW, and earlywood (EW). The 300 mg L−1 treatment significantly increased the WRT of EW. The IAA 100 mg L−1 + GA3 100 mg L−1 combination treatment significantly increased the layers and width of TW and LW by inducing cambium activity and increasing the rate of wood cell development. The WRT and lumen radial diameter (LRD) of EW or LW in this treatment were similar to those observed with the corresponding single phytohormone treatment. These results indicate that combination treatment at 100 mg L−1 + 100 mg L−1 was a better way to promote tree-ring growth. Our study suggests that changes in phytohormone levels and ratios are important factors that affect tree-ring formation. Hormone levels and ratios should be regarded as important indicators to guide the improvement of management practices in hybrid larch clonal plantations. [ABSTRACT FROM AUTHOR]

The strain variations in Elm earlywood and latewood during drying were studied with digital image correlation method. Also, the moisture contents of different water states were quantified based on time-domain nuclear magnetic resonance technique to reveal the strain-water relationships. Although the shrinkage strains gradually increased with increasing drying time, there was a significant difference in the strain distribution of the earlywood and latewood. Owing to latewood large stress, the earlywood was pulled by it to shrink together, and the earlywood maximum shrinkage appeared in the early/latewood junction, while the maximum shrinkage of latewood happened in its middle part. Wood shrinkage strain increased fast in the early-drying stage, mainly influenced by moisture content variation; in the mid-drying stage, the shrinkage increased slowly due to the synergistic effect of free and bound water migration; in the late-drying stage, the bound water variation led to a mild shrinkage. [ABSTRACT FROM AUTHOR]

The study material of Scots pine sample trees originated from five different forest site types (Cladonia, Calluna, Myrtillus, natural raised bog and drained raised bog) in Estonia. Altogether, 60 trees were sampled from 10 stands. From these, test disks and sample blocks (1.2 m in length) were cut at 1.3 m height, 1/2 of tree height and 3/4 of tree height. We analysed the effect of forest site type on the growth of tree ring width, proportion of late- and heartwood, oven-dry density, bending and compression strength and wood hardness. Wood properties in stands of the same age showed great variability. Significant differences were found in the wood properties between site types. Wood density and strength characteristics were higher in samples from heath site types than from the sites more optimal for pine (e.g., Myrtillus). The quality of the wood from peatland stands was lower than from trees grown on mineral soil. The decreasing trend in strength properties towards the top of trees was steeper in the wood formed under poor nutrient conditions. Latewood proportion increased with tree age. However, in the case of equal latewood percentages, heartwood density was higher than sapwood density.

Plantation forests were originally established in South Africa to meet an increasing demand for solid wood products as there was a limited supply from native forests. The majority of the commercial softwood plantations were established with Mexican Pinus patula. Since growing conditions are known to impact tree growth, tree form, and wood quality of P. patula, sample plots were established over a cross-section of plantations in the Lowveld Escarpment and Highveld forestry regions of South Africa that covered an array of geologies and altitudes. Each sample plot was classified according to soil properties, rainfall, and temperature, and trees within the plots were measured for growth, form, and wood properties. Soil, growing days, and temperature were found to have little impact on tree form and wood properties. However, rainfall and specifically, spring rainfall, was found to have a highly significant impact on late wood formation, proportion of juvenile core, and wood density. In addition, tree height was found to be strongly correlated with maximum annual temperature. [ABSTRACT FROM AUTHOR]

Hydroclimate affects the radial growth responses of trees, but the drivers of their spatial and population variability are not sufficiently understood. We addressed this issue by sampling several conifer populations located at the same latitude, but at different longitude and elevation in western (W) and eastern (E) Mexican regions. We used dendroecology to disentangle how earlywood width (EW), latewood width (LW) and adjusted LW (LWadj), i.e. the residuals after removing EW influences on LW, responded to climate variables (temperature and precipitation), climate indices (Southern Oscillation Index, SOI, Ni~no 3.4, Pacific Decadal Oscillation, PDO) and a drought index (Standardised Precipitation-Evapotranspiration Index, SPEI). The W species (Pinus herrerae Martínez, Pinus durangensis Martínez, Abies durangensis Martínez and Cupressus lusitanica Mill.) showed lower growth rates than the E species (Pinus hartwegii Lindl., Picea mexicana Martínez, Pseudotsuga menziesii (Mirb.) Franco and Abies vejari Martínez). Growth in W benefits mostly from high precipitation in the prior winter and current spring and it is limited by high temperatures in spring, whereas growth in the E showed similar but weaker responses. Furthermore, positive (negative) correlations were found in radial growth with the Ni~no 3.4 (SOI) and the PDO from the prior to current autumns, which were again stronger in absolute terms in the W than in the E regions, excepting SOI in summer. In the W, P. durangensis and C. lusitanica were the least and most responsive species to spring drought, respectively; whilst P. menziesii and A. vejari were very responsive to spring drought compared to P. hartwegii in the E. Our results suggest greater responsiveness to hydroclimate and atmospheric patterns in the W than in the E region. These findings allow better interpretations of future changes in growth and composition in Mexican conifer forests, considering that climate models forecast warmer spring conditions and increased water shortage. [ABSTRACT FROM AUTHOR]

This experiment was conducted in the pine woods of central Europe at a research area established in 1951. The experimental area of 1.35 ha was set up in a 14-year-old pine tree stand, which was divided into lots, and the pruning procedure took place in different variants. Some lots constituted control lots without pruned trees. The trees were pruned in four variants, reducing the living tree crown by 1/4, 1/3, 1/2, and 2/3 of its length. The study's main aim was to determine the influence of pruning forest trees on the tree tissue. Moreover, the study attempted to answer whether pruning was a significant procedure for wood valorisation, and if yes, then which variant was the optimal one for Scots pine growing on the European plain. The results indicated a significant impact of pruning young pine tree stands on the properties of wood tissue, which differed regarding the adopted pruning variant. Significant differences in the width of annual rings, the size of the particular areas of the annual rings (latewood or earlywood), and the wood density depending on the pruning variant were observed. Furthermore, the results indicated that pruning induced numerous processes, which optimised the physiological and mechanical functions of the tree trunks. The outcome of this optimisation was, among others, the diversification of the vascular and strengthening area of the annual ring as well as the wood density, which was a reaction to reducing a part of the assimilation apparatus. From the technical wood value viewpoint, the optimal pruning variant for pine was between 1/3 to 1/2 of the living crown. [ABSTRACT FROM AUTHOR]

Bark beetle outbreaks frequently kill large areas of loblolly pine (Pinus taeda). Resin production is the main defense against these insects and resin duct metrics and areas are correlated with both resin flow and tree survival post bark beetle attack. Whether the number, area, or size of resin ducts is increase when trees grow faster or whether there is a tradeoff between tree growth and resin ducts is currently debated. We determined the impacts of water availability (ambient vs 30 % throughfall reduction), nutrient availability (fertilized vs non-fertilized), and thinning on vertical resin duct count (ducts per 5 mm strip of annual ring), density (ducts mm−2), area (duct area per 5 mm strip of annual ring), relative area (% duct area per ring), and average duct size (mm−2) in planted stands of loblolly pine (ages 6–13) in southeastern Oklahoma. Fertilization increased diameter growth (10 %) and metrics that scale to ring width, i.e., duct count (15 %) and duct area (22 %), but also duct relative area (8 %). Throughfall exclusion decreased diameter growth and duct count in some years, increased duct density, and reduced duct average size (8 %). The net effect was that fertilized stands with ambient water availability had the greatest resource availability among treatments in this study and had the greatest duct count, duct area, and duct relative area as well as average duct size greater than the throughfall exclusion treatments. During the post thinning period, i.e., ages 10–13, thinning increased diameter growth from 9.63 to 12.05 mm year−1, duct count from 9.69 to 12.22, duct area from 0.384 to 0.514 mm2, duct relative area from 1.67 % to 1.84 %, and average duct size from 0.0396 to 0.0428 mm2. Earlywood composed approximately 2/3 of the annual ring, but latewood had almost 5 times greater duct density such that there were more ducts and greater duct areas in the latewood. Our assessment of duct metrics provides a link between tree growth rate, resource availability, and duct metrics associated with resistance to bark beetles. Therefore, silvicultural practices used to increase tree growth likely also increase resistance to bark beetles. • Effect of drought, fertilization, and thinning on vertical resin duct metrics were measured for loblolly pine. • Fertilization increased diameter growth, duct count, duct area, and duct relative area. • Throughfall exclusion decreased diameter growth and duct count in some years, increased duct density, and reduced duct size. • Thinning increased diameter growth, duct count, duct area, duct relative area, and average duct size. [ABSTRACT FROM AUTHOR]

The quantitative description of growth rings is yet incomplete, including the functional division into earlywood and latewood. Methods developed to date, such as the Mork criterion for conifers, can be biased and arbitrary depending on species and growth conditions. We proposed the use of modeling of the statistical distribution of tracheids to determine a universal criterion applicable to all conifer species. Thisstudy was based on 50-year anatomical measurements of Pinus sylvestris L., Pinus sibirica Du Tour, and Picea obovata Ledeb. near the upper tree line in the Western Sayan Mountains (South Siberia). Statistical distributions of the cell wall thickness (CWT)-to-radial-diameter (D) ratio and its slope were investigated for raw and standardized data (divided by the mean). The bimodal distribution of the slope for standardized CWT and D was modeled with beta distributions for earlywood and latewood tracheids and a generalized normal distribution for transition wood to account for the gradual shift in cell traits. The modelcan describe with high accuracy the growth ring structure for species characterized by various proportions of latewood, histometric traits, and gradual or abrupt transition. The proportion of two (or three, including transition wood) zones in the modeled distribution is proposed as a desired criterion.

Hydroclimate affects the radial growth responses of trees, but the drivers of their spatial and population variability are not sufficiently understood. We addressed this issue by sampling several conifer populations located at the same latitude, but at different longitude and elevation in western (W) and eastern (E) Mexican regions. We used dendroecology to disentangle how earlywood width (EW), latewood width (LW) and adjusted LW (LWadj), i.e. the residuals after removing EW influences on LW, responded to climate variables (temperature and precipitation), climate indices (Southern Oscillation Index, SOI, Niño 3.4, Pacific Decadal Oscillation, PDO) and a drought index (Standardised Precipitation-Evapotranspiration Index, SPEI). The W species (Pinus herrerae Martínez, Pinus durangensis Martínez, Abies durangensis Martínez and Cupressus lusitanica Mill.) showed lower growth rates than the E species (Pinus hartwegii Lindl., Picea mexicana Martínez, Pseudotsuga menziesii (Mirb.) Franco and Abies vejari Martínez). Growth in W benefits mostly from high precipitation in the prior winter and current spring and it is limited by high temperatures in spring, whereas growth in the E showed similar but weaker responses. Furthermore, positive (negative) correlations were found in radial growth with the Niño 3.4 (SOI) and the PDO from the prior to current autumns, which were again stronger in absolute terms in the W than in the E regions, excepting SOI in summer. In the W, P. durangensis and C. lusitanica were the least and most responsive species to spring drought, respectively; whilst P. menziesii and A. vejari were very responsive to spring drought compared to P. hartwegii in the E. Our results suggest greater responsiveness to hydroclimate and atmospheric patterns in the W than in the E region. These findings allow better interpretations of future changes in growth and composition in Mexican conifer forests, considering that climate models forecast warmer spring conditions and increased water shortage.

Tree-ring latewood is a key proxy for the reconstruction of climate, especially for temperature. The mechanisms of latewood formation and its responses to climates remain uncertain. Given that the tree-ring latewood of the taproot is absent belowground under conditions of low temperature gradients, we thus hypothesize that low diurnal temperature ranges (DTRs) may be one determining factor for latewood production. To evaluate this hypothesis, we designed experimental investigations by adding heat-protecting layers to the trunks of Pinus massoniana Lamb. to lower DTRs and simulate the environmental conditions underground in the Fuzhou area of humid subtropical China (HSC). We found that a decreased DTR induces a significant decline in latewood cell thickness and a slight reduction in latewood cell number and latewood density. DTRs played an important role in the formation of tree-ring width (TRW) and latewood width (LWW) rather than precipitation. Our study highlighted the effects of DTRs on tree growth and wood anatomical changes and provided a possible explanation for the "divergence problem" in dendroclimatology. [ABSTRACT FROM AUTHOR]

Dynamic mechanical analysis (DMA) and small angle X-ray scattering (SAXS) measurements of water-saturated wood of Douglas fir (Pseudotsuga menziesii) in the temperature range of 0 ℃ to 100 ℃ were focused to clarify microstructural changes within an annual ring. The following results were obtained. Thermal softening behavior caused by micro-Brownian motion of lignin was observed in both earlywood and latewood. The peaks of tanδ were found at around 95 ℃ for earlywood and at around 90 ℃ for latewood. These results suggested that the structures of lignin in the cell wall were different between earlywood and latewood. SAXS measurements of water-saturated earlywood and latewood in water were performed with precise temperature control. The scattering intensity increased with increasing temperature, indicating that the density of the matrix was reduced at higher temperature. One-dimensional SAXS intensity at the equator, which approximately represents cellulose microfibrils arrangement in the matrix, was intensively analyzed using the WoodSAS model. The result of this model fitting showed that the cellulose microfibril diameter of latewood was higher than that of earlywood. In addition, the value of interfibrillar distance decreased monotonically in the earlywood, while it decreased rapidly in the latewood from 60 ℃ to 90 ℃. The changes in the cellulose microfibril (CMF) diameter and the interfibrillar distance with increasing temperature between earlywood and latewood by SAXS measurement were different. The differences in CMF diameter and inter-fibril distance between earlywood and latewood measured by SAXS also support the hypothesis that lignin structure differs between earlywood and latewood based on the results of DMA measurements. [ABSTRACT FROM AUTHOR]

Thermal modification can increase the physical stability and impact the mechanical strength of wood. It is necessary to understand the effects of modifications on the compressive stress of wood. In this study, Douglas fir (Pseudotsuga menziessi) blocks were modified at 180 °C (TM-180 °C) and 210 °C (TM-210 °C). The compressive stress of pure earlywood (EW), pure latewood (LW), and combined earlywood and latewood (ELW) specimens was measured. The specimens were compressed at 30% of their original thickness, and during the compression test the strain distribution of the ELW was recorded. In addition, the microstructures before and after compression were investigated, complemented with SEM to understand the structural changes taking place. The results showed that the compressive stress of the TM-180 °C specimens was the highest because the thermal modification increased the stiffness of cell walls and the homogenized strain distribution in the ELW specimens. The control specimens had a higher compression set recovery rate than the thermally modified specimens. The tracheid cell walls in the EW and LW specimens were flattened and buckled, respectively, due to compression. In the thermally modified materials, cell wall fissures and wood ray fractures in the EW and LW specimens, respectively, were observed. For the ELW specimens, the structural changes in the latewood were not obvious and the structural changes in the earlywood were less significant than in the full EW specimens. Compared to the EW specimens, the earlywood in the ELW specimens showed higher compression set recovery rates. It seems that structural failure in earlywood is limited when used in combination with latewood, resulting from the homogenized strain distribution in earlywood.

This study investigated the variations in tracheid length of Pseudotsuga menziesii (Mirb.) Franco from three sites in Croatia in relation to cambium age, within- and between-site differences, and growth rate. Tracheids are the main structural element in P. menziesii wood, varying in length following different patterns that should be precisely determined. After the maceration procedure, earlywood tracheid length (EWTL), latewood tracheid length (LWTL), annual growth ring tracheid length (RTL), earlywood ring width (EWW), latewood ring width (LWW), and annual ring width (ARW) were measured in selected annual growth rings. The significant effect of annual growth rings and zone interaction for EWTL and LWTL, as well as of annual growth rings, trees, and sites for RTL, was determined. The results conclude on the differences between the trends in EWTL and LWTL from pith toward the bark. In addition, the correlation analysis between the tracheid length and different growth patterns was investigated, and very weak or no association between the variables was detected. This research contributes to better understanding the degree of wood uniformity of P. menziesii from the technological perspective, as well as the variability factor in the optimization of forest management with favoring overall wood quality.

Furfurylated wood has many advantages, such as decay resistance, dimensional stability, hardness, etc. However, furfurylation increases the brittleness and decreases the flexural resistance of wood, which greatly limits its application. Therefore, caprolactam (CPL) is incorporated with furfuryl alcohol (FA) to improve the performance of furfurylated wood. In this study, an FA and CPL combinational modifier was used to treat masson pine (Pinus massoniana Lamb.) earlywood and latewood. The synergistic interaction of both components with the wood cell walls was systematically evaluated via microstructural, chemical, and thermal analysis using scanning electron microscopy (SEM), infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometry (XPS), and differential scanning calorimetry (DSC). The SEM images showed that polymerized modifiers were distributed in tracheids, ray cells, and pits, with a higher degree of distribution in latewood tissues. The FA-CPL co-treatment led to the highest degree of distribution in cell cavities as well as of cell wall swelling. The results of the weight percentage gain (WPG) of modified wood agreed with the SEM findings that the FA-CPL co-treatment could more effectively increase the WPG than individual modification. The results of FTIR and XPS revealed that FA and CPL might chemically bind with each other as well as react with lignin and hemicellulose in the cell walls during the curing process. In addition, the interactions between modifiers and cell walls were slightly different for earlywood and latewood. DSC analysis indicated that the wood hygroscopicity decreased and the thermal stability improved after modification.

Brown rot fungi cause a type of wood decay characterized by carbohydrate degradation and lignin modification. The chemical and physical changes caused by brown rot are usually studied using bulk analytical methods, but these methods fail to consider local variations within the wood material. In this study we applied hyperspectral near infrared imaging to Scots pine sapwood samples exposed to the brown rot fungi Coniophora puteana and Rhodonia placenta to obtain position-resolved chemical information on the fungal degradative process. A stacked-sample decay test was used to create a succession of decay stages within the samples. The results showed that the key chemical changes associated with decay were the degradation of amorphous and crystalline carbohydrates and an increase in aromatic and carbonyl functionality in lignin. The position-resolved spectral data revealed that the fungi initiated degradation in earlywood, and that earlywood remained more extensively degraded than latewood even in advanced decay stages. Apart from differences in mass losses, the two fungi produced similar spectral changes in a similar spatial pattern. The results show that near infrared imaging is a useful tool for analyzing brown rot decayed wood and may be used to advance our understanding of fungal degradative processes. [ABSTRACT FROM AUTHOR]

Brown rot fungi cause a type of wood decay characterized by carbohydrate degradation and lignin modification. The chemical and physical changes caused by brown rot are usually studied using bulk analytical methods, but these methods fail to consider local variations within the wood material. In this study we applied hyperspectral near infrared imaging to Scots pine sapwood samples exposed to the brown rot fungi Coniophora puteana and Rhodonia placenta to obtain position-resolved chemical information on the fungal degradative process. A stacked-sample decay test was used to create a succession of decay stages within the samples. The results showed that the key chemical changes associated with decay were the degradation of amorphous and crystalline carbohydrates and an increase in aromatic and carbonyl functionality in lignin. The position-resolved spectral data revealed that the fungi initiated degradation in earlywood, and that earlywood remained more extensively degraded than latewood even in advanced decay stages. Apart from differences in mass losses, the two fungi produced similar spectral changes in a similar spatial pattern. The results show that near infrared imaging is a useful tool for analyzing brown rot decayed wood and may be used to advance our understanding of fungal degradative processes.

Climate change is predicted to cause asymmetric warming and increased precipitation variability across different seasons. These changes and their effects may be captured in subannual seasonwood measures of tree growth (i.e., earlywood, latewood). Longleaf pine is a foundational tree species throughout the broad southeastern U.S. Its latewood growth may be more variable and sensitive to climate change than earlywood, but prior studies have geographical and ecological sampling limitations. Here, we use dendroecological methods to develop ring-width and seasonwood (earlywood, latewood, and adjusted latewood) chronologies and analyze climate-growth relationships for longleaf pine from eight sites in the Southern Coastal Plain of Florida, USA. Sites spanned a range of environmental conditions to generate an ecologically representative dataset. We evaluated chronology strength and variability and determined monthly and seasonal correlations with precipitation and temperature. We furthermore evaluated climate-growth stationarity using a moving response function and bootstrapped transfer function stability tests. We found adjusted latewood chronologies were most climatically sensitive although totalwood chronologies had higher interseries correlations. Totalwood measurements were more variable than early- or latewood year to year. Tree growth was positively correlated with summer precipitation at six out of eight sites and negatively correlated with late summer maximum temperatures at six out of eight sites. Negative relationships between growth and maximum temperature occurred earlier in the year at southern sites and the positive effect of June precipitation on tree growth was notable, found at six out of eight sites. However, the strength and significance of climate-growth relationships were non-stationary through space and time, with shifts largely occurring post-1950s. Longleaf pine at its southern range extent was less sensitive to climate than more northern populations, which may indicate non-linear responses to warming captured at the species' range margin. Our results highlight dynamic climate-growth relationships related to the broad range of environmental conditions where longleaf pine is found. • Unique dendroecological methods show new insights in longleaf pine climate response. • Longleaf pine seasonwood chronologies exhibit differing climatic sensitivities. • Adjusted latewood chronologies were more sensitive to climate than other measures. • Climatic sensitivity in tree ring growth decreased in southern longleaf pine. • Climate-growth relationships are nonstationary in ecologically representative trees. [ABSTRACT FROM AUTHOR]

Defoliating insects' outbreaks play a critical role in trees' carbon cycle. The pine processionary moth (PPM; Thaumetopoea pityocampa) is the major defoliating insect of Mediterranean coniferous forests. The frequency and intensity of PPM outbreaks is projected to increase as winter temperatures become milder due to climate warming. An accurate evaluation of this projection requires a wide spatial baseline of the historical PPM incidence. PPM outbreaks affect tree secondary growth leading to narrow rings, providing a tree level signal. However, PPM defoliation rings can be confounded with drought rings, the most frequent cause of narrow rings in Mediterranean environments. Thus, an accurate identification of PPM rings demands the consideration of additional tree ring traits. Here, we introduce a multiproxy approach to identify and distinguish PPM and drought events. We sampled four Pinus nigra (3) and P. sylvestris (1) stands in Spain. We identified and verified years of PPM defoliation using remote sensing analysis and field observations of Regional Forest Service. We identified drought events through the combination of climatic data with radial growth reductions. We considered climate growth residuals, among-trees growth variability, latewood percentage (%LW), intrinsic water-use efficiency (iWUE) and minimum blue intensity (BI) to discern between droughts and PPM outbreaks. In comparison with drought rings, PPM rings showed 1) more negative residuals in climate growth models, 2) higher secondary growth variance, 3) higher percentage of latewood and 4) lower iWUE. Minimum BI did not differ between drought and PPM rings, but was lower than in the rest of the rings. The combination of these traits provides a signature to identify PPM rings, opening the opportunity to reconstruct PPM incidence on a broad spatio-temporal scale. [ABSTRACT FROM AUTHOR]

With the crisis awareness of global warming and natural disasters, utilization of local wood has drawn increasing attention in achieving the Sustainable Development Goals (SDGs). It is necessary to investigate the deformation and fracture of the structural tissue in wood in order to improve the safety and reliability of wood application. However, deformation and fracture mechanisms of the structural tissue in each annual ring are unknown. The mechanical characteristics of wood are reflected in the properties of earlywood and latewood. In the present study, microstructural observation and tensile tests were conducted to examine the relationship between the mechanical properties and fracture behavior of latewood in the growth direction in Japanese cedar. Brittle fracture behavior of the latewood specimen was confirmed based on the tensile stress–strain curve and features of the fracture surface. Moreover, two fracture modes, tensile fracture and shear fracture, were recognized. Weibull analysis of tensile strength in each fracture mode was performed to evaluate the reliability and utility of brittle latewood. Lastly, two fracture mechanisms were discussed based on the failure observation findings by a scanning electron microscope. [ABSTRACT FROM AUTHOR]

Studies linking wood properties of the southern pines to climate parameters and/or irrigation treatments have generally used seedlings or mid-rotation age trees, the latter comprised primarily of juvenile wood. To investigate possible drought-induced effects on mature wood physical properties, densitometry data from 50-year-old slash (Pinus elliottii Engelm.), longleaf (Pinus palustris Mill.), and loblolly (taeda L.) pine trees were matched with annual soil moisture values. Each of two growth ring groupings per increment core had a two-year period of ample moisture followed by a two-year period of drought; these were centered at ages of 20 and 38 years. For slash pine, the latewood width was 30% lower (p = 0.011) for the drought period at age 20. Seemingly similar results were obtained for longleaf pine, but the probability (p = 0.051) just exceeded the threshold for significance (α = 0.05). No differences were observed for either earlywood or total ring widths. Ring specific gravity (SG) values that were 11% lower for slash pine and 7% lower for longleaf pine can be attributed to drought-related reductions in latewood formation. Unlike other studies with younger trees, both percent latewood and ring SG values for mature loblolly pine were unaffected by drought. [ABSTRACT FROM AUTHOR]

A dendroecological study of the annual ring parameters of Scots pine (Pinus sylvestris L.) trees growing in the forest-steppe and steppe zones of Eastern Transbaikalia has been carried out. Using the methods of digital anatomy of annual rings, two (Nov and Tz) tree-ring chronologies based on four parameters (annual ring width, earlywood width, latewood width, and latewood optical density) have been constructed for the studied territory for the first time. A comparative analysis of the chronologies has made it possible to evaluate tree growth parameters under conditions of the forest-steppe (Nov) and steppe (Tz) zones and reveal the presence of reliable relations between them. The calculation of moving correlation coefficients reveals period*s when correlation coefficients fell below reliable values, indicating the impossibility of constructing a generalized regional chronology for the forest-steppe and steppe zones of Eastern Transbaikalia. A comparison of the chronologies with the weather parameters (ground air temperature and precipitations), as well as with the calculated drought and moisture indices (Selyaninov's hydrothermal coefficient, Ped's drought index, and Palmer drought severity index (PDSI)) reveal the most sensitive characteristics of annual rings in the studied area. In the forest-steppe zone, the highest correlation coefficients are obtained between the average annual precipitation and the annual ring width (r = 0.59) or the earlywood width (r = 0.59), as well as between the average air temperature for a hydrological year and the latewood width (r = 0.51). For the trees from the steppe zone, the most significant correlation is revealed between the annual precipitation and the annual ring width (r = 0.43) or earlywood width (r = 0.43), as well as between the PDSI for June–September and the earlywood width (r = 0.52). [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the influence of day and night meteorological parameters (air temperatures and dew points, relative humidity, wind speed and precipitation) on the radial growth of pine latewood in northern taiga, in typical conditions of its growth. The study was conducted in the north of the Arkhangelsk region (Russia). A total of 63 cores were selected from seven most representative sites. Meteorological parameters were obtained from the WMR 918 H digital weather station (Huger GmbH, Germany), located directly on the study area and operating in monitoring mode. The analysis used meteorological data for the period 2008–2015. Correlation with night and day air temperature in June and July (0.72–0.77) was revealed in blueberry type. In all the stands studied, a reliable correlation with wind speed was established, direct (0.77–0.88) and inverse (−0.7 to −0.99), but each sample plot had an individual dependence. A reliable correlation with the humidity of August and September (0.64–0.87) and an inverse correlation with precipitation in May and August (−0.63 to −0.75) were established. In general, pine in blueberry, cowberry and pine on swamp types have a similar reaction to the variability of meteorological factors, the most important of which is the temperature regime of air and wind speed. [ABSTRACT FROM AUTHOR]

This research investigates the sub-annual climate response of ten Pinus lambertiana and eight Pinus jeffreyi from Yosemite, and ten Pinus monticola and ten Pinus jeffreyi from Sequoia. We investigate the potential of using resin ducts to measure the earlywood and latewood of P. lambertiana and P. monticola and compare this growth with co-occurring, traditionally measured P. jeffreyi. Correlation analyses of ring widths with average monthly temperature, vapor pressure deficit (VPD), and precipitation were conducted. Our results show that the resin duct method performed poorly at both sites but better with P. lambertiana at Yosemite. Species at both sites generally have a positive correlation with precipitation. Earlywood and latewood correlations with climate were relatively weak. Temperature and VPD correlations were generally positive in the spring and negative in the summer months at both sites for all three species. These results reveal that future increases in temperature and VPD will leave these trees vulnerable to future droughts. More samples are needed throughout the Sierras to determine if the resin duct method can be used for subannual climate reconstructions, if these results can be generalized, and if sub-annual reconstructions are possible for these three species. [ABSTRACT FROM AUTHOR]

The study material of Scots pine sample trees originated from five different forest site types (Cladonia, Calluna, Myrtillus, natural raised bog and drained raised bog) in Estonia. Altogether, 60 trees were sampled from 10 stands. From these, test disks and sample blocks (1.2 m in length) were cut at 1.3 m height, 1/2 of tree height and 3/4 of tree height. We analysed the effect of forest site type on the growth of tree ring width, proportion of late- and heartwood, oven-dry density, bending and compression strength and wood hardness. Wood properties in stands of the same age showed great variability. Significant differences were found in the wood properties between site types. Wood density and strength characteristics were higher in samples from heath site types than from the sites more optimal for pine (e.g., Myrtillus). The quality of the wood from peatland stands was lower than from trees grown on mineral soil. The decreasing trend in strength properties towards the top of trees was steeper in the wood formed under poor nutrient conditions. Latewood proportion increased with tree age. However, in the case of equal latewood percentages, heartwood density was higher than sapwood density. [ABSTRACT FROM AUTHOR]

The inter- and intra-annual variability in radial growth reflects responses to climatic variability and water shortage, especially in areas subjected to seasonal drought. However, it is unknown how this variability is related to forest productivity, which can be assessed by measuring changes in canopy greenness and cover through remote sensing products as the Normalized Difference Vegetation Index (NDVI). We combine xylogenesis with measurements of inter-annual changes in seasonal wood production (earlywood width, adjusted latewood width) and NDVI to improve the understanding of climate and drought impacts on growth and forest productivity in a Pinus teocote stand located in northern Mexico. Cambial dynamics accelerated in March and a high production of radially enlarging and thickening tracheids were observed from April to October and from June to October, respectively. Tracheid maturation was very active in October when latewood production peaked. Wet conditions in winter-spring and summer-autumn enhanced earlywood and latewood production, respectively. Earlywood and latewood were constrained by long (4–10 months) and short (2–3 months) droughts, respectively. The earlywood production depended on April soil moisture, which agrees with the peak of radially enlarging tracheid production found during that month. Aligning drought proxies at inter- and intra-annual scales by using growth and productivity measures improves our understanding of conifer forest responses to water shortage. [ABSTRACT FROM AUTHOR]

Global warming is affecting tree growth and forest productivity, especially in the Northern boreal ecosystems. Wood quality, which is largely determined by anatomical traits of wood, is vital for the forest industry and global carbon sequestration. Cambium activity, wood density, fiber length and microfibril angle are the anatomical traits that determine wood quality, depending on market demands. Within the global warming scenario, a comprehensive understanding of these traits is still lacking and urgently required for both the forest industries and ecological researches. In this review, we identify that large proportions of mature wood, high wood density, longer fiber or tracheid length and low microfibril angles are the anatomical traits closely related with high wood quality. Higher temperatures could trigger onset and ending of cambial cell division, thus affecting wood quality by modulating duration of the growing season. Climate warming could also affect wood quality by impacting earlywood and latewood formation, as well as changing wood density, fiber length and microfibril angle depending on different species and growing conditions. In addition, this review indicates that the anatomical traits involved in wood quality are diverse and depend on the intended use. Improving our knowledge about the underlying mechanisms of how the wood anatomical traits respond to a changing environment with extreme climate events is thus still a crucial topic in the forest sciences. Selection of species and provenances best adapted to climate warming will be necessary to improve quality without sacrificing volume. Studies on wood traits and their relation to climate should therefore focus on a multitude of aspects including the physiology and genetics of boreal tree species.

This experiment was conducted in the pine woods of central Europe at a research area established in 1951. The experimental area of 1.35 ha was set up in a 14-year-old pine tree stand, which was divided into lots, and the pruning procedure took place in different variants. Some lots constituted control lots without pruned trees. The trees were pruned in four variants, reducing the living tree crown by 1/4, 1/3, 1/2, and 2/3 of its length. The study’s main aim was to determine the influence of pruning forest trees on the tree tissue. Moreover, the study attempted to answer whether pruning was a significant procedure for wood valorisation, and if yes, then which variant was the optimal one for Scots pine growing on the European plain. The results indicated a significant impact of pruning young pine tree stands on the properties of wood tissue, which differed regarding the adopted pruning variant. Significant differences in the width of annual rings, the size of the particular areas of the annual rings (latewood or earlywood), and the wood density depending on the pruning variant were observed. Furthermore, the results indicated that pruning induced numerous processes, which optimised the physiological and mechanical functions of the tree trunks. The outcome of this optimisation was, among others, the diversification of the vascular and strengthening area of the annual ring as well as the wood density, which was a reaction to reducing a part of the assimilation apparatus. From the technical wood value viewpoint, the optimal pruning variant for pine was between 1/3 to 1/2 of the living crown.

Tree-ring latewood is a key proxy for the reconstruction of climate, especially for temperature. The mechanisms of latewood formation and its responses to climates remain uncertain. Given that the tree-ring latewood of the taproot is absent belowground under conditions of low temperature gradients, we thus hypothesize that low diurnal temperature ranges (DTRs) may be one determining factor for latewood production. To evaluate this hypothesis, we designed experimental investigations by adding heat-protecting layers to the trunks of Pinus massoniana Lamb. to lower DTRs and simulate the environmental conditions underground in the Fuzhou area of humid subtropical China (HSC). We found that a decreased DTR induces a significant decline in latewood cell thickness and a slight reduction in latewood cell number and latewood density. DTRs played an important role in the formation of tree-ring width (TRW) and latewood width (LWW) rather than precipitation. Our study highlighted the effects of DTRs on tree growth and wood anatomical changes and provided a possible explanation for the “divergence problem” in dendroclimatology.

Wood and phloem formation databases are important for understanding the effects of climate change and extreme weather events on species composition, tree vitality, wood production and wood quality in Slovenian forests. In this paper, we present the latest results on the radial growth of Norway spruce (Picea abies (L.) Karst.) at two sites in Slovenia, Panška reka (PAN – 400 m a. s .l.) and Menina planina (MEN – 1200 m a. s .l.) in 2009–2011. The focus was on the seasonal dynamics of early and latewood, and early and late phloem formation. We found that site conditions greatly affected the seasonal dynamics of wood and phloem formation, which was reflected in the width and structure of annual increments. At the higher elevation MEN site, the growing season was about a month shorter (about 4 months long), which resulted in 39% and 15% narrower wood and phloem increments, respectively. At MEN, the transition from early to latewood was observed on average only a week later than at PAN, while the transition from early to late phloem occurred on average 20 days later at MEN than at PAN. Information on the impact of site conditions on radial growth of spruce and wood quality is important for all stakeholders in the forest-wood value chain, as it can help to take appropriate management measures of adaptation to changing conditions.