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Key message: Terrestrial laser scanning data of trees combined with models of heartwood content proportion of woody disks can provide precise characterization of total aboveground tree sapwood and heartwood volume. Quantifying sapwood and heartwood content of trees is challenging. Previous studies have primarily characterized main stem wood composition, while branches have rarely been studied. Terrestrial Laser Scanning (TLS) can provide precise representations of the entire above-ground tree structure, non-destructively, to help estimate total tree sapwood and heartwood volume. In this study, we used TLS to scan above-ground portions of twenty-four open-grown, urban Gleditsia triacanthos trees on Michigan State University campus. TLS data were used to generate quantitative structure models that provided comprehensive characterizations of the total tree woody surface area (WSA) and volume. A subsample of trees was harvested (after scanning) and main stem and branch woody disks were collected to build models of heartwood content proportion. Models were applied to measurements from TLS to quantify complete heartwood and sapwood volume of each tree, including main stem and branches. From the base to the top of the trees, the largest portion of stem vertical cumulative volume was heartwood, whereas vertical cumulative volume of branches showed the opposite pattern. Absolute heartwood volume declined monotonically toward zero from stem base to stem top, while absolute sapwood volume declined sharply from stem base up to near the crown base and then remained relatively constant within crown. We also found that tree WSA increased with sapwood volume for both branches and main stem. This study developed a novel, general method for quantifying total aboveground sapwood and heartwood volume of trees and provided new insights into urban tree growth and structure. [ABSTRACT FROM AUTHOR]

The characteristics of heartwood and sapwood not only reflect tree growth and site quality but also provide insights into habitat changes. This study examines the natural Populus euphratica Oliv. forest in the Arghan section of the lower Tarim River, comparing the heartwood and sapwood characteristics of P. euphratica at different distances from the river, as well as at varying trunk heights and diameters at breast height (DBH). The objective was to examine the correlation between these characteristics and the physicochemical properties of the soil to better understand the ecological response strategies of P. euphratica in arid environments. Results indicated that heartwood radius, sapwood width, sapwood area, and heartwood moisture content decreased with increasing trunk height, following the pattern: 0.3 m > 0.8 m > 1.3 m. In contrast, heartwood density increased as trunk height increased. Most of the heartwood and sapwood indicators increased with larger tree diameters. In the case of P. euphratica with a DBH of less than 45 cm, the difference in moisture content between heartwood and sapwood was not significant (p > 0.05) at heights of 0.3 m and 0.8 m. However, at a height of 1.3 m, the difference was significant (p < 0.05). Soil analysis revealed that factors such as total nitrogen, available potassium, and water content significantly influenced the physical characteristics of P. euphratica heartwood and sapwood across different sites. Redundancy analysis (RDA) further demonstrated that total nitrogen, available phosphorus, and soil moisture were significantly correlated with the physical properties of P. euphratica heartwood and sapwood, further validating the critical role of soil nutrients in shaping the wood characteristics of P. euphratica. These findings highlighted the specific adaptations of P. euphratica in the lower Tarim River to the arid desert environment, reflected in the observed relationships between soil conditions and the physical characteristics of heartwood and sapwood. [ABSTRACT FROM AUTHOR]

Heartwood, serving as the central constituent of the xylem, plays a crucial role in the growth, development, and resilience of trees. The process of heartwood formation constitutes a complex biological phenomenon influenced by various factors. A thorough examination of the mechanisms underpinning heartwood formation not only enhances our understanding of the growth and developmental paradigms regulating trees but also provides essential theoretical support and practical insights for the timber industry, forestry management, and ecological conservation. This paper offers an overview of the foundational processes involved in heartwood formation in plants. Furthermore, it presents a comprehensive review of the latest research advancements in this domain, covering five key aspects: metabolism, hormonal regulation, transcriptional regulation, cell biology, and environmental influences. This review serves as a valuable basis for future research endeavors in related academic fields. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the influence of age on the colorimetric parameters, chemical composition, and biological resistance of teak heartwood, transition zone, and sapwood. Samples of 13- and 22-year-old trees were collected from fast-growing commercial plantations in Mato Grosso, Brazil. From the heartwood, transition zone, and sapwood sections, we determined the CIEL*a*b* system colorimetric parameters and extractive contents and performed Py-CG/MS analysis and an accelerated degradation assay with the xylophagous fungus Trametes versicolor (L.) Lloyd. The 22-year-old wood presented greater redness and lower yellowness, and the heartwood was darker, with greater redness and lower yellowness than the other radial positions. The average content of total extractives varied between ages: 7.83% (13years) and 8.23% (22years). A total of 119 compounds were identified in teak wood, of which 51 presented areas greater than 1%. Quinones were identified in the heartwood and transition zone, with similar values between ages and approximately 7% in the heartwood. Although the durability increased significantly with age, the magnitude was slight. Wood from 22-year-old trees exhibited a lower average mass loss (10.30%) compared to wood from 13-year-old trees (12.68%). In contrast, differences between regions were more pronounced. Sapwood showed a mass loss of 22.5%, transition zone wood of 10.14%, and heartwood of 1.86%. We concluded that age influenced the colorimetric parameters, chemical composition, and biological resistance of teak wood. Teak heartwood from fast-growing plantations, both from final harvesting (22-years-old) and from thinning (13-years-old), is indicated for uses that require high biological resistance. [ABSTRACT FROM AUTHOR]

Summary Carbon reserves are distributed throughout plant cells allowing past photosynthesis to fuel current metabolism. In trees, comparing the radiocarbon (Δ14C) of reserves to the atmospheric bomb spike can trace reserve ages. We synthesized Δ14C observations of stem reserves in nine tree species, fitting a new process model of reserve building. We asked how the distribution, mixing, and turnover of reserves vary across trees and species. We also explored how stress (drought and aridity) and disturbance (fire and bark beetles) perturb reserves. Given sufficient sapwood, young (< 1 yr) and old (20–60+ yr) reserves were simultaneously present in single trees, including ‘prebomb’ reserves in two conifers. The process model suggested that most reserves are deeply mixed (30.2 ± 21.7 rings) and then respired (2.7 ± 3.5‐yr turnover time). Disturbance strongly increased Δ14C mean ages of reserves (+15–35 yr), while drought and aridity effects on mixing and turnover were species‐dependent. Fire recovery in Sequoia sempervirens also appears to involve previously unobserved outward mixing of old reserves. Deep mixing and rapid turnover indicate most photosynthate is rapidly metabolized. Yet ecological variation in reserve ages is enormous, perhaps driven by stress and disturbance. Across species, maximum reserve ages appear primarily constrained by sapwood longevity, and thus old reserves are probably widespread. [ABSTRACT FROM AUTHOR]

Summary: Resource storage is a critical component of plant life history. While the storage of nonstructural carbohydrates in wood has been studied extensively, the multiple functions of mineral nutrient storage have received much less attention. Here, we highlight the size of wood nutrient pools, a primary determinant of whole‐plant nutrient use efficiency, and a substantial fraction of ecosystem nutrient budgets, particularly tropical forests. Wood nutrient concentrations also show exceptional interspecific variation, even among co‐occurring plant species, yet how they align with other plant functional traits and fit into existing trait economic spectra is unclear. We review the chemical forms and location of nutrient pools in bark and sapwood, and the evidence that nutrient remobilization from sapwood is associated with mast reproduction, seasonal leaf flush, and the capacity to resprout following damage. We also emphasize the role wood nutrients are likely to play in determining decomposition rates. Given the magnitude of wood nutrient stocks, and the importance of tissue stoichiometry to forest productivity, a key unresolved question is whether investment in wood nutrients is a relatively fixed trait, or conversely whether under global change plants will adjust nutrient allocation to wood depending on carbon gain and nutrient supply. [ABSTRACT FROM AUTHOR]

Summary: Co‐occurring plants show wide variation in their hydraulic and photosynthetic traits. Here, we extended 'least‐cost' optimality theory to derive predictions for how variation in key hydraulic traits potentially affects the cost of acquiring and using water in photosynthesis and how this, in turn, should drive variation in photosynthetic traits.We tested these ideas across 18 woody species at a temperate woodland in eastern Australia, focusing on hydraulic traits representing different aspects of plant water balance, that is storage (sapwood capacitance, CS), demand vs supply (branch leaf : sapwood area ratio, AL : AS and leaf : sapwood mass ratio and ML : MS), access to soil water (proxied by predawn leaf water potential, ΨPD) and physical strength (sapwood density, WD).Species with higher AL : AS had higher ratio of leaf‐internal to ambient CO2 concentration during photosynthesis (ci : ca), a trait central to the least‐cost theory framework. CS and the daily operating range of tissue water potential (∆Ψ) had an interactive effect on ci : ca. CS, WD and ΨPD were significantly correlated with each other. These results, along with those from multivariate analyses, underscored the pivotal role leaf : sapwood allocation (AL : AS), and water storage (CS) play in coordination between plant hydraulic and photosynthetic systems.This study uniquely explored the role of hydraulic traits in predicting species‐specific photosynthetic variation based on optimality theory and highlights important mechanistic links within the plant carbon–water balance. See also the Commentary on this article by Macinnis‐Ng, 244: 1681–1683. [ABSTRACT FROM AUTHOR]

Compositional and anatomical studies of silicified wood have been carried out extensively all around the world. The classification of silicified wood as such deals with all the forms and phases of silica that come under its umbrella. One such class of silicified wood is fossil wood with a high content of quartz, and there are very limited mentions of this category of fossilized wood. The examined wood belongs to gymnosperm and comes from the Upper Triassic deposits of Madagascar. A fresh approach to such samples is adopted by studying the crystallographic texture of the fossil wood to understand the orientation of the crystals replacing the organic matter within the sample. This work focuses on crystallographic texture analysis based on pole figures measured by X-ray diffraction. The intensity of the pole density maxima on the pole figures measured on the heartwood surface part of the analyzed samples is higher than that on the sapwood. This affirms that the crystallographic texture is sharper at the heartwood part compared to the sapwood. The X-ray tomography study, conducted to understand the difference in mineral distribution within the sample, reveals a greater X-ray absorbing phase on the sapwood of both samples. This is due to the concentration of iron compounds, which both replace the remaining conductive structures of the wood and fill the cavities inside them. We believe that this research on silicified wood is the first research work that encompasses crystallographic texture analysis with pole figures, an approach not previously undertaken in similar studies. We hope that our research can be useful in understanding the processes of replacement of organic matter by minerals. [ABSTRACT FROM AUTHOR]

Olive wood is used in a niche economic context but is attracting growing interest. In this study, the wood anatomy of Olea europaea L. belonging to two cultivars cultivated in the Plain of Gioia Tauro in Calabria (RC) is qualitatively described. Wood samples were obtained along the diameter of wood slices to investigate any anatomical differences between the inner and outer zones of the stem. The microscopic slides were investigated using an optical microscope. The anatomical characteristics observed were compared with existing literature data. The two cultivars show parenchyma rays arranged not only in one to two rows (typical of this species), but also in three rows. Furthermore, in both cultivars, the presence of starch deposits in procumbent parenchyma cells was observed. The Ottobratica cultivar seems to have more starch than the Sinopolese one, but given the high variability of olive wood, further quantitative analysis is needed to determine whether these differences are statistically valid and due to the different cultivars. This work can contribute to a better understanding of the Olea europaea L. species and to a better technical valorisation of its wood. [ABSTRACT FROM AUTHOR]

The commercial value of teak wood is associated with its heartwood, which has a naturally darker color than sapwood. To reduce this color disparity, thermal modification can be used to homogenize the color between sapwood and heartwood by minimizing color differences. This research aimed to assess the effectiveness of thermal modification in making the color of teak sapwood similar to that of heartwood. Thermal modification was carried out at 160, 180, 200, and 220 °C for 150 min. Thermal modification of teak sapwood at 180 °C ensured greater color similarity to the heartwood of a fast-growing 16-year-old plantation. The material darkened with increasing process temperature. There was a change in the content of soluble substances, and hot water extraction had greater correlations with hue angle, lightness, and yellowness. Thermal modification also reduced the number of hydroxyl groups and improved the wood's thermal stability. [ABSTRACT FROM AUTHOR]

The durability of small-diameter larch wood was studied with respect to its treatments with wood tar and wood vinegar in three environments-- underground, underwater, and outdoors--for 53 months. This study involved assessing wood cell wall deterioration using optical microscopy, X-ray computed tomography imaging, and X-ray diffraction, along with evaluating various physical and mechanical properties using Korean standards. Severe deterioration was observed in vinegar-treated sapwood after being buried underground. Collapsed cells were often found in untreated and wood vinegar-treated wood buried underground. Noticeable decreases in the physical and mechanical properties were observed in the sapwood of wood vinegar-treated wood buried underground. The wood tar-treated wood buried underground remained relatively intact with minimal changes in its physical properties. No significant degradation was observed in the wood discs submerged in water, and there was no difference in density, shrinkage, hardness, and shear strength between the untreated and preserved wood submerged in water. Under outdoor conditions, wood vinegar-treated wood showed less degradation of the wood discs than untreated and wood tar-treated wood. In conclusion, wood tar enhanced the durability of the wood when it was buried in soil, whereas the wood vinegar treatment provides an advantage when exposed to outdoor conditions.. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment of wood, particularly steaming with saturated water steam, is often used to achieve a more intensive and homogenous wood color or to vary its hue. However, information on pear wood (Pyrus communis L.) steaming is limited in the available literature. This paper investigates the influence of steaming on the color of pear wood. Green, water-saturated samples of pear wood heartwood and sapwood were steamed with saturated water steam for 24 h at 98 °C. The color of the heartwood and sapwood was assessed both visually and with a standard three-stimulus colorimeter using the CIEL*a*b* system, and compared to the natural color of pear-wood. Additionally, FT-IR spectrometry was employed to analyze chemical changes in the wood samples. The results showed that both heartwood and sapwood experienced a decrease in lightening (L*), an increase in redness (a*), and a decrease in yellowness (b*) during steaming. Furthermore, a trend toward the equalization of L*, a*, and b* parameters between heartwood and sapwood over time was observed. FT-IR spectroscopy revealed that the chemical changes during steaming were primarily related to extractives and hemicelluloses, with no significant changes in cellulose and lignin. The obtained results suggest that pear wood color can be equalized to some extent by steaming and that the extent of the color change to darker tones is dependent on steaming time. [ABSTRACT FROM AUTHOR]

Sorting of sawn timber batches is crucial for efficient kiln-drying. This study aimed to verify the hypothesis of different drying attributes of 25 mm thick sapwood and mixed Scots pine boards sawn from a group of butt, second, and top logs and assess the effects of kiln-drying. Three options dry-bulb temperature were taken into account. The drying results were evaluated based on the final moisture content distribution, changes in the cross-sectional dimensions of the sawn timber, drying time, and unit heat consumption. Correlations between sawn timber features, drying temperature, and drying results were analyzed using non-parametric statistical tests. The study proved the dependence of the initial moisture content and wood density variation of Scots pine sawn timber on the log type and the position on the round timber cross-section. The variation of drying attributes of the sapwood and mixed 25 mm Scots boards is insignificant in the final moisture content distribution and cross-sectional dimensions. However, green sorting may have only a beneficial effect on drying time and heat consumption. [ABSTRACT FROM AUTHOR]

Ray parenchyma cells are involved in the initiation of heartwood formation. The position within a ray influences the timing of ray parenchyma cell differentiation and function; however, there is little information concerning the positional influence on the cellular changes of ray parenchyma cells from sapwood and heartwood. In this study, radial variations inmorphology, size, and ultrastructure of ray parenchyma cells were studied by combined transmission electron microscopy and optical microscopy. Results showed that cellular traits of ray parenchyma cells in Populus tomentosa were all affected by both radial position in the secondary xylem and position within a ray. Specifically, radial variations in cellular traits weremore evident in isolation cells, which were not adjacent to vessel elements. Both cell length and cell width/length ratio of isolation cells were bigger than contact cells, which contacted adjacent vessel elements via pits. Moreover, the secondary wall thickening and lignification of contact cells developed in the current-year xylem, much earlier than isolation cells. Secondary walls in contact cells were in a polylamellate structurewith a protective layer on the inner side. No alteration in the ultrastructure of contact cells occurred in the sapwood-heartwood transition zone, except that most contact cells died. By contrast, in the transition zone, isolation cells still lived. A thin secondary wall began to deposit on the thick primary wall of isolation cells, with two isotropic layers on the inner side of the primary wall and secondary wall respectively being characteristic. Meanwhile, starch grains in isolation cells were depleted, and dark polyphenolic droplets lost their spherical shape and flowed together. Furthermore, the intercellular spaces of isolation cells became densified in the transition zone. Overall, cellular changes suggested that the positional information of ray parenchyma cells appeared to be an important factor in the transformation from sapwood to heartwood. Unlike contact cells, isolation cells were more elongated, specialized in radial transport, had a delayed formation of secondary walls, and were involved in the synthesis of heartwood substances. Our result promotes the elucidation of the involvement of xylem rays in heartwood formation. [ABSTRACT FROM AUTHOR]

The importance of maintaining a healthy indoor climate has recently increased, as has the durability of building structures, and for this issue, we need to predict mould growth. To prepare this model under real conditions is challenging, and this work aimed to contribute data to this model. This article presents the findings of a laboratory study investigating the effects of fluctuations in the relative humidity and temperature conditions on mould growth on pine and spruce. The study compared the results to a previous steady-state experiment, demonstrating that fluctuations in relative humidity and temperature prolonged the onset of mould growth. The mould growth observed depended on the type of wood with pine or spruce wood exhibiting different growth patterns compared to heartwood or sapwood. In sapwood, mould growth was found to be almost independent of the direction of the fiber. The first microscopic indications of mould growth on pine sapwood were observed around day 76, with the first macroscopic indications observed around day 90. On the contrary, spruce sapwood demonstrated a limit for mould growth. The mould growth was only visible under the microscope with the first indications observed between the 72nd and 80th day. Furthermore, heartwood was found to be unsuitable for mould growth under fluctuating conditions. [ABSTRACT FROM AUTHOR]

Ophiostoma haidanensis is described as a new species of the Ophiostoma piceae complex isolated from yellow-cedar (Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little) sapwood in the Haida Gwaii island archipelago and the North Coast of British Columbia, Canada. The fungus is characterized by the production of a typical sporothrix-like asexual morph but is distinguished morphologically from other members of the O. piceae species complex by its large, multiseptate primary conidia. Phylogenetic analysis of DNA sequences from the nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and the β-tubulin (BTUB) and translation elongation factor 1-α (TEF1) genes supports the inclusion of O. haidensis as a distinct member within the O. piceae complex. To our knowledge, this is the first report of a blue stain fungus infecting yellow-cedar, an ecologically, culturally, and economically important conifer naturally distributed along the coastal forests of the Pacific Northwest in North America. [ABSTRACT FROM AUTHOR]

The smoke from Combretum hartmannianum and Terminalia laxiflora sapwood and fermented heartwood (nikhra) are used in body smoke baths and homemade skincare products in Sudan, which are believed to have various health benefits. In this study, the volatiles of sapwood and nikhra were collected using two extraction techniques: a Mono-TrapTM sampling technique (at low temperature) and a smoke trapping system (at high temperature). After GC-MS analysis, the chromatogram of each sample revealed numerous peaks. The detected peaks were identified using the DIST08 mass spectral library database, resulting in known and unknown compounds. The results showed that 1,2,4,5-tetrachloro-3,6-dimethoxybenzene was the major compound in the Mono-Trap and smoke extracts from nikhra samples of C. hartmannianum and T. laxiflora. In contrast, the dominant compounds in the Mono-Trap extracts of C. hartmannianum and T. laxiflora sapwoods were acetonyldimethylcarbinol and cadina-1(10),4-diene, respectively. The largest peaks in the chromatograms of the sapwood smoke extracts of both species corresponded to unknown compounds. Some of the detected compounds are known for their aromatic and pharmaceutical properties. Identifying these aromatic compounds in nikhra and not in sapwood might prove the traditional Sudanese beliefs, and it could potentially improve the manufacturing of health products. [ABSTRACT FROM AUTHOR]

The combination of different wood-modification technologies to obtain improved performance is increasingly receiving attention in research. In this study, Scots pine (Pinus sylvestris) sapwood was impregnated with furfuryl alcohol (FFA) in pure aqueous 20, 40, and 60% solution strength without adding any catalyst. In a second step, the FFA was polymerized while simultaneously performing thermal modification in a closed system at 130, 150, or 180 °C. After leaching and ageing tests, the nine different combinations were tested in use class 4 applications (in contact with or very close to the ground and frequently wet) according to CEN/TS 15083-2 (2005) decay laboratory test. It was noted that even the minimum-intensity combination of 20% FFA at 130 °C resulted in maximum durability class (DC) 1 performance. On the contrary, DC 4 was assigned to thermally modified control samples, even at the maximum intensity of thermal modification. Similarly, for FFA modifications, previous research has suggested that an uptake of 35% solution strength is required to obtain an adequate durability performance in use class 4 applications. High levels of resistance against termites were also noted by corresponding termite lab tests. Moisture studies showed the combined treatments resulted in improved stability and reduced moisture uptakes. Thus, the results obtained by this study revealed synergistic performance effects, which originate from the combined thermo-chemical modification approach, and which were higher than simple accumulation of the individual performance of purely thermally or chemically modified wood. Thus, the presented findings have provided positive implications for industrial applications of thermo-chemical modification techniques and offers an array of new research opportunities. [ABSTRACT FROM AUTHOR]

Abstract The material properties of sapwood and heartwood vary within various wood species and even they can show significant differences within a single tree. Scots pine (Pinus sylvestris L.), a species that plays a crucial role in timber production for joinery and building construction applications, is among those that show a notable distinction between its heartwood and sapwood. To examine the influence of moisture content (MC) on the impact behaviour of the sapwood and heartwood of pine, we tested specimens with two distinct moisture levels: a low moisture content (LMC) group with 12% MC and a high moisture content (HMC) group with 45% MC. In our study, we investigated deflection, normal strain and force development of the specimens during the short period of an impact, and also calculated the impact bending strength (IBS) of samples, using an impact testing machine equipped with a high-speed camera and digital image correlation method. Our results indicate that the differences between sapwood and heartwood at LMC were insignificant in the case of maximum deflection and normal strain, thus there is no need for differentiation; however, these differences became more pronounced, and non-negligible, with an increase in MC. We also evaluated the IBS of both heartwood and sapwood and found that, at LMC, heartwood had greater impact bending strength than sapwood, making it a preferable choice as a material subjected to impact loadings. Conversely, at HMC, both heartwood and sapwood would be equally strong against impacts, indicating that pine green wood shows no sensitivity to the ratio of sapwood to heartwood in the tree.

Abstract This work deals with the influence of different heat treatment temperatures (140, 150, 160, 170, 180, 190, 200, and 210 °C) on changes in sapwood and red heartwood of European beech (Fagus sylvatica L.). According to the results of wet chemistry methods, HPLC (high-performance liquid chromatography), FTIR (Fourier transform infrared spectroscopy), SEC (size exclusion chromatography), the wood constituents in sapwood and red heartwood behaved similarly to heat treatment, but the individual proportions were different. The loss of hemicelluloses and the increase in extractives with increasing temperature were more pronounced in sapwood. The amount of cellulose in sapwood and red heartwood showed similar behaviour with increasing temperature. Thermal treatment causes changes in cellulose crystallinity, and the formation of aromatic structures, mainly in beech sapwood. However, the increase in the lignin content of red heartwood was significantly lower than that of sapwood due to its auto condensation, and formation of pseudo-lignin. Among the carbohydrates, the most significant changes were observed in xylose content, which was almost twice as high in red heartwood as in sapwood. Other carbohydrates (glucose, mannose, galactose, and arabinose) reached similar values in sapwood and red heartwood.

The material properties of sapwood and heartwood vary within various wood species and even they can show significant differences within a single tree. Scots pine (Pinus sylvestris L.), a species that plays a crucial role in timber production for joinery and building construction applications, is among those that show a notable distinction between its heartwood and sapwood. To examine the influence of moisture content (MC) on the impact behaviour of the sapwood and heartwood of pine, we tested specimens with two distinct moisture levels: a low moisture content (LMC) group with 12% MC and a high moisture content (HMC) group with 45% MC. In our study, we investigated deflection, normal strain and force development of the specimens during the short period of an impact, and also calculated the impact bending strength (IBS) of samples, using an impact testing machine equipped with a high-speed camera and digital image correlation method. Our results indicate that the differences between sapwood and heartwood at LMC were insignificant in the case of maximum deflection and normal strain, thus there is no need for differentiation; however, these differences became more pronounced, and non-negligible, with an increase in MC. We also evaluated the IBS of both heartwood and sapwood and found that, at LMC, heartwood had greater impact bending strength than sapwood, making it a preferable choice as a material subjected to impact loadings. Conversely, at HMC, both heartwood and sapwood would be equally strong against impacts, indicating that pine green wood shows no sensitivity to the ratio of sapwood to heartwood in the tree. [ABSTRACT FROM AUTHOR]

This work deals with the influence of different heat treatment temperatures (140, 150, 160, 170, 180, 190, 200, and 210 °C) on changes in sapwood and red heartwood of European beech (Fagus sylvatica L.). According to the results of wet chemistry methods, HPLC (high-performance liquid chromatography), FTIR (Fourier transform infrared spectroscopy), SEC (size exclusion chromatography), the wood constituents in sapwood and red heartwood behaved similarly to heat treatment, but the individual proportions were different. The loss of hemicelluloses and the increase in extractives with increasing temperature were more pronounced in sapwood. The amount of cellulose in sapwood and red heartwood showed similar behaviour with increasing temperature. Thermal treatment causes changes in cellulose crystallinity, and the formation of aromatic structures, mainly in beech sapwood. However, the increase in the lignin content of red heartwood was significantly lower than that of sapwood due to its auto condensation, and formation of pseudo-lignin. Among the carbohydrates, the most significant changes were observed in xylose content, which was almost twice as high in red heartwood as in sapwood. Other carbohydrates (glucose, mannose, galactose, and arabinose) reached similar values in sapwood and red heartwood. [ABSTRACT FROM AUTHOR]

Hydraulic traits are major determinants of plant fitness, thus exerting control over vegetation structure, function and distribution. Yet it remains unclear whether and how hydraulic traits respond to environmental stimuli (i.e. phenotypic variation of hydraulic traits; PVHT) and if the coordination between different hydraulic traits and the trait–climate relationship are affected by PVHT.Here, we synthesized data of PVHT (maximum hydraulic conductivity and water potential inducing 50% loss of hydraulic conductivity) and potentially related morphological and anatomical traits (e.g. sapwood density, branch Huber value, mean and hydraulic weighted conduit diameter). We analysed the magnitude, direction and source of variation of the plastic response, as well as the influence of environmental factors on trait coordination. Additionally, we compared the intra‐ and inter‐specific variation between key hydraulic traits and climate metrics (mean annual precipitation and mean annual temperature) at the site of growth, as well as across the population range.PVHT was highly variable in both magnitude and direction, which was contingent on the environmental factor. The variation in PVHT mainly occurred at high taxonomic levels (i.e. family and genus), whereas phenology explained little variation for PVHT. Despite the high variability, trait correlation remained robust in the presence of environmental stimuli. Moreover, trait–climate relationships differed at inter‐specific and intra‐specific levels. The intra‐specific variation of hydraulic traits in most species showed no correlation with climate metrics compared with the high correlation of hydraulic traits with climate metrics across species.Our findings suggest that the high variability of PVHT does not affect the trait correlation which may be valuable in predicting vegetation dynamics under varying environments. The distinct trait–climate relationships highlight the need to unravel the driving force of PVHT, as well as the adaptive strategy across populations. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Paraserianthes falcataria, locally known as Batai, is a non-native, fast-growing species selected by Malaysia's forest plantation programme. Limited empirical studies have been conducted regarding this species, specifically the one planted domestically. A comprehensive understanding of its wood properties is essential to effectively introduce and utilise this species commercially. Thus, a study was conducted to evaluate the physicomechanical properties of Batai and their correlation with age and position variation. In this study, P. falcataria was harvested from a forest plantation in Kuala Krai, Kelantan, Malaysia, encompassing three different age variations: 2.5, 5 and 8 years. Five replicates were felled for each age, and the logs were segmented into three 2 m portions representing variations along the vertical axis: top, middle and bottom. Additionally, radial variation was examined by distinguishing between heartwood and sapwood. Subsequently, samples were tested with static bending and compression tests following standard protocols (ISO 13061-3: 2014, ISO 13061-4, and ISO 13061-17: 2017). The results revealed statistically significant physico-mechanical properties among different ages and within-tree sections. This study provides valuable documentation on P. falcataria wood properties, contributing to the field's knowledge. Moreover, it exposes the harvesting determinants towards the planters and wood industry, facilitating better utilisation of P. falcataria wood across various applications. [ABSTRACT FROM AUTHOR]

Pterocarpus erinaceus, sourced from natural stands, is famed for producing naturally durable heartwood for several outdoor wood products, which has contributed to overharvesting and threats of extinction. The species coppices could offer essential strategy in curbing timber over-exploitation towards sustainable management. This study aimed to establish confidence in utilizing the coppiced wood in accordance with the EN 252 standard (European Committee for Standardization). Mass loss of wood specimens and appearance grading were used to evaluate termite resistance within the coppiced and non-coppiced stems. Mass loss due to termites was much lower in heartwood than in sapwood, this was true for wood coming from the non-coppiced and coppiced stands. It generally decreased from the butt to the top/crown of both trees. Heartwood and sapwood along each tree species would be highly and moderately resistant against termite attack respectively. Due to their high durability, the rosewood trees would be suitable for engineering applications. Thus the promotion of the coppiced P. erinaceus wood production would supplement the use of its non-coppiced counterpart to increase the wood market base. [ABSTRACT FROM AUTHOR]

Wood constitutes a unique and valuable material that has been used from ancient times until nowadays in a wide variety of applications, in which the surface quality of wood often constitutes a critical factor. In this study, the influence of different wood areas and therefore, of different anatomical characteristic areas of chestnut wood (Castanea sativa Mill.) on the surface quality, was thoroughly studied, in terms of surface roughness. Five different chestnut tree trunks were harvested, from which five different disks were obtained corresponding to five different trunk heights. Surface roughness was measured on these disks on the transverse, radial, and tangential planes, on the areas of sapwood and heartwood, measuring the roughness in each point both vertically and in parallel to the wood grain. The results revealed that the examined roughness indexes (Ra, Rz, Rq) follow a parallel path to one another. In the case of all surfaces (transverse, radial, tangential) of the disks examined, when the measurement was implemented perpendicularly to the wood grain, a significantly higher roughness was recorded, compared to the wood grain measurements being implemented in parallel with the wood grain. Significant differences between heartwood and sapwood roughness were not demonstrated, although sapwood often appeared to exhibit a higher surface roughness than heartwood sites. Among the roughness values of the three different surfaces, the highest roughness in the vertical-to-wood-grain measurements was recorded by tangential surfaces, with slightly lower values on the transverse surfaces and the lowest roughness on radial surfaces. Meanwhile, for the measurements in parallel with the wood grain, the transverse surfaces presented significantly higher roughness values compared to the tangential and radial surfaces. Significant roughness differences were not detected among the surfaces at different trunk heights. Although, significant differences in roughness were recorded among different trees, it was observed that all the studied trees align with the identified and described within-tree trends. [ABSTRACT FROM AUTHOR]

This study aimed to investigate and compare the non-anatomical characteristics of six Korean oak wood species (Quercus variabilis, Q. serrata, Q. mongolica, Q. dentata, Q. aliena and Q. acutissima) to provide identification keys and quality indices for the effective utilization of these species. Non-anatomical characteristics, including heartwood fluorescence, fluorescence and color of water and ethanol extracts, froth test, chrome azurol S test and burning splinter test, were evaluated according to the International Association of Wood Anatomists (IAWA) lists. None of the six Korean oak species displayed heartwood fluorescence or fluorescence in the ethanol extract. Only Q. serrata exhibited bright blue fluorescence in the aqueous extract. Each species showed distinct colors in both water and ethanol extracts, and the water extract of all species was darker than that of the ethanol extract. A weak positive reaction in the froth test was observed only for Q. serrata. Furthermore, Q. variabilis and Q. acutissima showed positive reactions to both heartwood and sapwood in the chrome azurol S test. The burning splinter test revealed that only Q. acutissima was transformed into charcoal. Thus, water extract fluorescence and color, ethanol extract color, froth test, chrome azurol S test, and burning splinter test can be used to identify the six Korean oak species. [ABSTRACT FROM AUTHOR]

Hypoallometric (slope<1) scaling between metabolic rate and body mass is often regarded as near-universal across organisms. However, there are compelling reasons to question hypoallometric scaling in woody plants, where metabolic rate is directly proportional to leaf area. This leaf area must provide carbon to the volume of the metabolically active sapwood (V MASW). Within populations of a species, variants in which V MASW increases per unit leaf area with height growth (e.g. ⅔ or ¾ scaling) would have proportionally less carbon for growth and reproduction as they grow taller. Therefore, selection should favor individuals in which, as they grow taller, leaf area scales isometrically with shoot V MASW (slope=1). Using tetrazolium staining, we measured total V MASW and total leaf area (LAtot) across 22 individuals of Ricinus communis and confirmed that leaf area scales isometrically with V MASW, and that V MASW is much smaller than total sapwood volume. With the potential of the LAtot– V MASW relationship to shape factors as diverse as the crown area–stem diameter relationship, conduit diameter scaling, reproductive output, and drought-induced mortality, our work indicates that the notion that sapwood increases per unit leaf area with height growth requires revision. [ABSTRACT FROM AUTHOR]

In this study, heartwood, sapwood, and copper-chromium-boron (CCB) impregnated sapwood samples of various tree species, including Scots pine (Pinus sylvestris L.), Caucasian spruce (Picea orientalis (L.) Peterm), European beech (Fagus orientalis L.) and common alder (Alnus glutinosa subsp. barbata), with dimensions of 20x20x300 mm, were investigated. These samples were subjected to soil contact, specifically under conditions of hazard class 4 according to EN 252, for a period of 3 years. The study was conducted in four different provinces of Turkey, namely Trabzon, Muğla, Çanakkale and Elazığ, which are characterized by different climatic conditions. The climatic index and soil structures of the sites were studied. The visual decay, weight loss and density values of the samples collected from the test sites were evaluated. Samples from Elazığ had the lowest visual decay rate, the lowest weight loss and the highest density. More negative values were observed in Çanakkale, Muğla and Trabzon. In terms of climate type, it was found that the Scots pine and Caucasian spruce wood samples have higher resistance than the European beech and common alder samples. In particular, the heartwood of conifers was found to be more durable than the sapwood. In addition, no deformation was observed in any of the impregnated wood samples. All impregnated wood samples exhibited very good durability. [ABSTRACT FROM AUTHOR]

This paper aims to quantify the surface roughness after the CNC milling of selected wood species. Optimization of the essential milling parameters, rotational speed, and feed speed is desirable for reducing surface roughness. Both technological parameters significantly contribute to the amount of feed per tooth, affecting surface roughness. In the experiment, three economically important wood species were compared – beech, oak, and spruce wood. In addition, the zones of sapwood, mature wood, and false heartwood were evaluated in beech wood. The surface roughness after milling was assessed using the Keyence VHX7000 digital microscope. The main result of the experiment is represented by the determination of the combination of the parameters mentioned above that produces the lowest roughness. In addition, roughness measurements were supplemented by microscopic analysis to explain roughness changes occurring on the surface. [ABSTRACT FROM AUTHOR]

Background The mechanisms leading to dieback and death of trees under drought remain unclear. To gain an understanding of these mechanisms, addressing major empirical gaps regarding tree structure–function relations remains essential. Scope We give reasons to think that a central factor shaping plant form and function is selection simultaneously favouring constant leaf-specific conductance with height growth and isometric (1:1) scaling between leaf area and the volume of metabolically active sink tissues ('sapwood'). Sapwood volume–leaf area isometry implies that per-leaf area sapwood volumes become transversely narrower with height growth; we call this 'stretching'. Stretching means that selection must favour increases in permeability above and beyond that afforded by tip-to-base conduit widening ("ultra-widening permeability"), via fewer and wider vessels or tracheids with larger pits or larger margo openings. Leaf area–metabolically active sink tissue isometry would mean that it is unlikely that larger trees die during drought because of carbon starvation due to greater sink–source relationships as compared to shorter plants. Instead, an increase in permeability is most plausibly associated with greater risk of embolism, and this seems a more probable explanation of the preferential vulnerability of larger trees to climate change-induced drought. Other implications of selection favouring constant per-leaf area sapwood construction and maintenance costs are departure from the da Vinci rule expectation of similar sapwood areas across branching orders, and that extensive conduit furcation in the stem seems unlikely. Conclusions Because all these considerations impact the likelihood of vulnerability to hydraulic failure versus carbon starvation, both implicated as key suspects in forest mortality, we suggest that these predictions represent essential priorities for empirical testing. [ABSTRACT FROM AUTHOR]

Tree phenology and wood traits are considered of foremost importance in understanding species' responses to the influence of climate change, thus the existence of a link between tree phenology and wood traits has become increasingly appealing in forestry research. The aim of this study was to explore the relationship between leaf flushing and wood traits (basic wood density, tree ring width, tree ring phenology, sapwood width and number of sapwood rings) in sessile oak (Quercus petraea (Matt.) Liebl.). We investigated trees with distinctive phenological behaviour (early flushing and late flushing) from three peripheral populations, one non-peripheral population and one sessile oak comparative trial close to the species eastern distribution range in the Eastern Carpathians. Covariance analysis, partial correlations, nonparametric statistics, and Principal Component Analysis were used to investigate the link between tree phenology, wood density, and some structural metrics. It was statistically confirmed that, at comparable ages and radial growth, the sessile oak trees exhibiting late leaf flushing had lighter basic wood density and greater density differences between sapwood and heartwood than early flushing trees. Independent of age, trees with intermediate flushing have wider rings, the formation of which is much earlier than in early flushing trees. At the same age, late trees from geographically peripheral populations have a higher number of sapwood rings. Also, the results revealed that peripheral populations had lower basic wood density, while this was not the case for peripheral provenances tested in the comparative trail established in an ecologically optimal area. These findings help us enlarge our understanding of the relationship between leaf flushing and wood traits, which could be useful for improving sessile oak management strategies near the eastern limit of the sessile oak natural range, which is becoming more and more critical in the context of the current climate changes. [ABSTRACT FROM AUTHOR]

This study aimed to determine the influence of increased temperature on the mass loss, chemical composition, and colour of pine wood because of the lack of such information. The colour was measured on samples of wood, extracted sawdust, holocellulose, and lignin isolated from the extracted sawdust of pine heartwood and sapwood. A wood sample labelled 20 °C was considered as wood with the original composition. Subsequently, we verified the measured values with the proposed mixing colour model. Pine heartwood and sapwood samples were thermally treated at temperatures of 100, 150, 200, 220, 240, and 260 °C for 1, 3, and 5 h. It was found that sapwood degraded faster than heartwood. The thermal treatment of wood increases lignin content and decreases holocellulose content, especially at 260 °C. The maximum extractive content of 3.60% was at 1 h and a temperature of 260 °C for both parts of the wood. Lightness values decreased with increasing temperature and time of treatment. The coordinate a* of heartwood showed a positive slope until one hour of treatment duration and a temperature of 240 °C. Then, it decreased for the subsequent duration of treatment. The same course was shown for the coordinate b* of sapwood at a temperature of 200 °C. The proposed model of mixing colours proved that changes in both parts of a wood-extracted substance, holocellulose, and lignin content, were responsible for the changing colour of extracted wood. [ABSTRACT FROM AUTHOR]

Both Ceratocystis lukuohia and C. huliohia have been associated with Rapid ʻŌhiʻa Death (ROD), an emerging threat to ʻōhiʻa (Metrosideros polymorpha), a keystone forest tree species. The vascular wilt disease caused by C. lukuohia has been recently described and is responsible for the widespread ROD epidemic on Hawai'i Island. However, the role of C. huliohia in ROD development and tree death is not clear. Artificial inoculation of field‐grown ʻōhiʻa with C. huliohia and dissections of naturally infected, early symptomatic forest trees were conducted to confirm pathogenicity on field grown trees and the pattern of internal colonization. In two trials, crowns of trees with main stems inoculated with C. huliohia were visually healthy at the time of tree harvest after 43–55 days in the first trial, and after 91 days in the second trial. However, elliptical inner bark cankers underlain by reddish‐brown xylem were associated with the inoculation points. Similar canker and stain symptoms were found on stems and branches of ʻōhiʻa (24–26 cm trunk diameter) naturally infected by C. huliohia. This xylem stain manifested as multiple distinct elliptical cankers or the coalescing of multiple cankers. The pathogen was commonly isolated from the perimeter of the stained outer sapwood and to a depth of 4 cm. The coalescence of multiple cankers was associated with the crown symptoms observed on the naturally infected forest trees that were dissected. Multiple C. huliohia infections that lead to coalescing cankers which subsequently girdle stems likely occurs over one or more years compared to the shorter time (e.g., months) required for C. lukuohia‐caused death to occur. [ABSTRACT FROM AUTHOR]

This work presents the results of the homogenization of the color of sapwood and false heartwood Fagus sylvatica L. into a uniform color shade due to the influence of the temperature of saturated moist air and saturated water steam in individual steaming modes. The results of analyses of the influence of temperature within 24 h point out the different changes in the color of the sapwood and the wood of the false heartwood when the uniform color of the beech wood is achieved by the steaming process. By steaming beech wood with a false heartwood saturated with moist air at a temperature of tI = 95 °C during τ = 24 h, the color of the sapwood does not merge with the color of the wood of the false heartwood. The sapwood darkens and, on the other hand, the wood of the false heartwood slightly lightens, while the significant color contrast is removed, but the color homogenization in the individual zones does not occur. The unification of the colors in individual zones occurs during the steaming process at a temperature of saturated water steam tII ≈ 105 °C in 18 h, where the resulting brown color is identified in the color space CIE L*a*b* by the values of the lightness L* = 61.3 ± 2.2 and of the red color a* = 12.4 ± 1.3 and yellow color b* = 19.5 ± 1.4. The most pronounced homogenization of the color occurs through the steaming process at a temperature of saturated water steam tIII ≈ 120 °C, where the wood acquires a uniform dark brown–gray color in a time of τ ≈ 9 h steaming. The coordinates of the color-homogenized steamed beech wood are L* = 55.9 ± 1.9, a* = 12.3 ± 1.2, and b* = 19.6 ± 1.3. The unification of the colors by the steaming process is achieved by darkening both the sapwood and the wood of the false heartwood. In the overall color homogenization, the sapwood and the wood of the false heartwood do not participate equally in the steaming process. While the total color difference between the sapwood and a color homogenized state is quantified by the value ∆EtI* = 8, ∆EtIII* = 22.7, the total color difference in the wood with a false heartwood is only ∆EtI* = 1.9, ∆EtIII* = 11.8. [ABSTRACT FROM AUTHOR]

A sapwood tree is a species in which the sapwood does not differ significantly from the heartwood and cannot be classified by shades of color. It is generally accepted that heartwood has a higher economic value than sapwood, but most of the studies related to heartwood formation have focused on heartwood trees, with less research on sapwood trees. In this paper, we take the sapwood tree Schima superba as the research object and analyze the physiological and biochemical changes in the process of heartwood formation by studying the anatomical structure of parenchyma cells, and then further explore the main categories of metabolites and compositional changes. The results showed that during heartwood formation, the parenchyma cells become inactive and the nucleus disappears, while at the same time, the storage substance starch is gradually degraded under the action of enzymes and transformed into secondary metabolites, which include terpenoids, phenols and alkaloids. The accumulation of white and colorless compounds in large quantities in the heartwood, which has some effect on the heartwood color, is an important reason why the heartwood in Schima superba shows normal formation but no difference in color from the sapwood. This study fills a gap in the mechanism of heartwood formation in sapwood trees. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the combined effect of steaming and heating on the equilibrium moisture content (EMC) of Turkey oak (Quercus cerris L.) wood over a nine-year period. The study also aimed to determine the impact of steaming on water absorption and water permeability, crucial for the durability of the species against environmental factors. The specimens underwent thermal modification with and without steaming, then were stored under laboratory conditions for ten years. The mass of the specimens was monitored throughout the ten-year period. To measure the water uptake capacity, the specimens were soaked in water for 120 hours. The water permeability of the specimens was assessed using a pressurised chamber. The results showed that the moisture content of thermally-modified oak was constant under laboratory conditions after nine years, further improved by steam treatment. The research also revealed that the steamed wood absorbed more water during water submersion compared to the unmodified wood. When the steaming treatment was applied, there was a significant increase in permeability in the sapwood compared to the heartwood, due to anatomical variations. Despite this, statistical noise, and material variability, alongside tylosis presence, underline the need for examining more specimens in future studies. [ABSTRACT FROM AUTHOR]

Background and Aims Heartwood plays an important role in maintaining the structural integrity of trees. Although its formation has long been thought to be driven solely by internal ageing processes, more recent hypotheses suggest that heartwood formation acts as a regulator of the tree water balance by modulating the quantity of sapwood. Testing both hypotheses would shed light on the potential ecophysiological nature of heartwood formation, a very common process in trees. Methods We measured quantities of heartwood and sapwood, xylem conduits and the width and number of growth rings on 406 stems of Pericopsis elata with ages ranging from 2 to 237 years. A subset of 17 trees with similar ages but varying growth rate were sampled in a shaded (slower-growth) site and a sun-exposed (faster-growth) site. We used regression analysis and structural equation modelling to investigate the dynamics and drivers of heartwood formation. Key Results We found a positive effect of growth rate on the probability of heartwood occurrence, suggesting an earlier heartwood onset in faster-growing stems. After this onset age, heartwood area increased with stem diameter and age. Despite the similar heartwood production per unit stem diameter increment, shaded trees produced heartwood faster than sun-exposed trees. Tree age and hydraulics showed similar direct effects on heartwood and sapwood area of sun-exposed trees, suggesting their mutual role in driving the heartwood dynamics of sun-exposed trees. However, for shaded trees, only tree hydraulics showed a direct effect, suggesting its prominent role over age in driving the heartwood dynamics in limited growing conditions. The positive relationship between growth rate and maximum stomatal conductance supported this conclusion. Conclusions Heartwood area increases as the tree ages, but at a slower rate in trees where water demand is balanced by a sufficient water supply. Our findings suggest that heartwood formation is not only a structural process but also functional. [ABSTRACT FROM AUTHOR]

Tectona grandis L. f. (teak) is highly valued in the international market, but its volume and properties vary depending on its genetic material and planting site. Evaluating these factors is crucial for promoting new plantations. Therefore, this study aimed to assess the impact of genetic material (clones TG1 and TG3 and seminal material) and planting site (Nova Maringá and Água Boa, Mato Grosso, Brazil) on morphological parameters (heartwood, sapwood, bark, pith proportions, and pith eccentricity), physical properties (shrinkage and air-dry density), and mechanical properties (static bending strength—fm, compressive strength—fc0, Janka hardness—fH90, and shear strength—fv0). For this purpose, we sampled five trees aged 13 years per genetic material from commercial plantations. In Nova Maringá, trees exhibited, on average, 56.07% heartwood, while in Água Boa, this value was less than 50%. Seminal material showed the lowest percentage of heartwood (49.2%). The pith percentage was significantly greater in Água Boa than in Nova Maringá, regardless of the genetic material. We observed the highest standard deviation (5.61) in pith eccentricity for the seminal material. Both the planting site and genetic material influenced the air-dry density (~12% moisture content), which ranged from 0.535 to 0.618 g·cm−3. Trees grown in Nova Maringá produced wood with higher dimensional stability than those from Água Boa, exhibiting a 14% lower radial shrinkage and a 6% lower volumetric variation. In Nova Maringá, the wood from the seminal material exhibited greater resistance. On the other hand, in Água Boa, that material showed lower resistance (fv0, fm, and fc0), or there was no significant difference (fH90) compared to the clonal materials. When comparing the clonal materials (TG1 and TG3) at each planting site, they demonstrated similar mechanical properties. The variability in physical and mechanical properties among different genetic materials and planting locations highlights the need to select appropriate teak genetic materials for each region. We concluded that more productive teak clones can be selected without compromising the physical and mechanical properties of the wood. [ABSTRACT FROM AUTHOR]

Heat treatment effectively inhibits the water absorption recovery of compressed wood. To elucidate this phenomenon, we prepared compressed pine and thermally compressed pine (heartwood and sapwood) using the hot pressing method at 160 °C, 180 °C, 200 °C, and 220 °C. The effects of chemical components, swelling stresses, and monosaccharides on modified wood recovery were investigated using regression analyses. Notably, the recovery of both compressed heartwood and sapwood during water absorption declined from 18.89% to 2.66% and from 58.40% to 1.60%, respectively, after heat treatment. Similarly, the swelling stresses of the compressed heartwood and sapwood at 220 °C, respectively, ranged from 0.693 MPa to 0.275 MPa and from 0.783 MPa to 0.330 MPa. These were close to the values of untreated heartwood (0.175 MPa) and sapwood (0.225 MPa). Regression functions indicated that the recovery of compressed wood is chemically dependent on hemicellulose and mechanically related to swelling stress. For monosaccharides, regression functions indicated that modified heartwood recovery primarily relied on mannose, whereas modified sapwood recovery was remarkably affected by mannose and xylose. This confirmed that the pyrolytic monosaccharides in hemicellulose promoted stress relaxation, which induced the deformation fixation of thermally compressed wood. [ABSTRACT FROM AUTHOR]

Summary: Tree stem methane emissions are important components of lowland forest methane budgets. The potential for species‐specific behaviour among co‐occurring lowland trees with contrasting bark characteristics has not been investigated.We compare bark‐mediated methane transport in two common lowland species of contrasting bark characteristics (Melaleuca quinquenervia featuring spongy/layered bark with longitudinally continuous airspaces and Casuarina glauca featuring hard/dense common bark) through several manipulative experiments.First, the progressive cutting through M. quinquenervia bark layers caused exponential increases in methane fluxes (c. 3 orders of magnitude); however, sapwood‐only fluxes were lower, suggesting that upward/axial methane transport occurs between bark layers. Second, concentrated methane pulse‐injections into exposed M. quinquenervia bark, revealed rapid axial methane transport rates (1.42 mm s−1), which were further supported through laboratory‐simulated experiments (1.41 mm s−1). Laboratory‐simulated radial CH4 diffusion rates (through bark) were c. 20‐times slower. Finally, girdling M. quinquenervia stems caused a near‐instantaneous decrease in methane flux immediately above the cut. By contrast, girdling C. glauca displayed persistent, though diminished, methane fluxes.Overall, the experiments revealed evidence for rapid 'between‐bark' methane transport independent from the transpiration stream in M. quinquenervia, which facilitates diffusive axial transport from the rhizosphere and/or sapwood sources. This contrasts with the slower, radial 'through‐bark' diffusive‐dominated gas transportation in C. glauca. See also the Commentary on this article by Ward & Megonigal, 242: 5–7. [ABSTRACT FROM AUTHOR]

Phenol-formaldehyde (PF) resins can be impregnated and cured in situ to improve the woods dimensional stability and decay resistance. In search of renewable alternatives, the substitution of phenol by lignin cleavage products (LCP) has been discussed. However, the different chemical nature may affect the performance of the resin against fungal decay, formaldehyde emission, and equilibrium moisture content. In this study, 30 % (w/w) of the phenol in PF resins were substituted by LCP obtained from microwave-assisted pyrolysis. Scots pine sapwood was modified with the resin. The decay resistance against Rhodonia placenta, Gloeophyllum trabeum, and Trametes versicolor was determined. Additionally, effects of specimen organisation within the Petri dish, different substrates, length of leaching, and type of inoculum were studied. Further, the materials water vapor sorption properties and formaldehyde emission were determined. All modifications effectively reduced fungal decay. With 10 % weight percent gain (WPG), initial decay was detected, while 20 % WPG and 30 % WPG provided efficient protection. The substitution of phenol increases the formaldehyde emission. While further reduction in formaldehyde in the resin admixture or formaldehyde scavengers may be required, the method described herein can be used to partly replace fossil-based phenol, while maintaining good fungal resistance. [ABSTRACT FROM AUTHOR]

Carbon fraction (CF) of trees is essential for quantifying forest carbon (C) stocks. Considerable attention has been paid to CF variations at various levels with the exception of inter- and intra-growth rings. Herein, the inter- and intra-growth ring variation of CF in Pinus tabuliformis was investigated. Elemental analysis was performed to obtain CF values of the earlywood and latewood in each growth ring of the xylem. Patterns of CF variation at the growth ring level were evaluated using mixed-effect models. The results showed that latewood CF, 50.6 %, was significantly higher than earlywood CF, 49.9 % (p < 0.01). In particular, inter-growth ring variations of CF differed between heartwood and sapwood, as well as between juvenile wood and mature wood. CF values decreased nonlinearly with cambium age toward the heartwood or juvenile wood, with estimated least-squares means of 50.4 % and 51.8 %, respectively. While CF values were almost unaltered in sapwood, and slightly decreased in mature wood, with estimated least-squares means of 50.0 % and 50.2 %, respectively. It indicates that patterns of CF variation between juvenile wood and mature wood are important to estimate the C stock of P. tabuliformis. This research provides insights into C uptake dynamics to support forest management and wood utilization. [ABSTRACT FROM AUTHOR]

Wood pellets produced from fresh sawdust can form and release uncontrolled gases during bulk storage, a tendency referred to as off-gassing. This study investigated the off-gassing tendencies of Scots pine wood pellets made from separated sapwood and heartwood sawdust. The effects of drying temperature, raw material storage, as well as varying proportions of sapwood and heartwood were also investigated. There was a strong linear correlation between off-gassing and sapwood content, with correlation coefficient (R) values greater than 0.9 at p < 0.001 for all the off-gases. An increase in sapwood content of the feedstock led to a significant increase in off-gassing of CO2, CO, and CH4, and O2 consumption. The drying temperature of the raw material had a significant effect on off-gassing of both sapwood (F(8, 26) = 51.32, p < 0.05) and heartwood (F(8, 26) = 334.1, p < 0.05) pellets. Increasing the drying temperature for heartwood resulted in increased off-gassing, while for sapwood, the off-gassing reduced. Storage of sapwood raw material before pelletization reduced the off-gassing of wood pellets, whereas for heartwood, it had no significant impact. Based on the results, it is suggested that a biological process, in combination with the chemical oxidation of fatty acids, lay behind the off-gassing of wood pellets. [ABSTRACT FROM AUTHOR]

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The increasing scarcity of major commercial tropical hardwood species has necessitated the utilization of plantation grown exotic timber species as a potential means of maintaining Ghana's foundation of timber resources. To better consider Albizia lebbeck as a substitute for wood species which are being seriously over-exploited to the point of commercial extinction, its wood properties were characterized to expatiate its utilization potentials. Three mature plantation grown Albizia lebbeck trees with diameters 45-50 cm at breast height were purposively selected and sampled at four stem height levels of tree height. The samples were sawn into the required sizes in accordance with the British standard, BS 373 (1957) for testing. The heartwood and sapwood proportions were evaluated and the samples were examined for hardness, bending strength (MOE and MOR), compression strength parallel to grain, shear strength parallel to grain, and air-dry density. All trees had a significantly higher heartwood than sapwood percentage. The air-dry density values at 12% MC were 868 kg/m3, 806 kg/m3, 695 kg/m3 and 564 kg/m3 for four sections of the stem (heights 0-25%, 26-50%, 51-75% and 76-100%). In general, the plantation grown Albizia lebbeck exhibited favourable strength values, suggesting that it is endowed with adequate properties for being an alternative species to supply the wood industry.