Heartwood Area Research Articles

The 30/100 Classification System as a Reference for Price of Sandalwood (Santalum album) Wood in Sandalwood Oil Industry

The perfume and cosmetics industry heavily relies on quality raw materials, particularly Sandalwood oil, known for its unique scent and importance in various products. The presence of a reliable Sandalwood oil distillation industry is crucial for meeting industry demands. However, determining the price of Sandalwood wood faces challenges due to quality variations influenced by factors like geographical origin and processing methods. We have proposed a 30/100 classification system developed by CV. Suraya Nirmala and UPT Laboratorium Terpadu of Universitas Nusa Cendana. The aim of this research is to determine the sandalwood oil content of several raw materials with a 30/100 classification system as a basis for determining the price of these raw materials. The classification method involves categorizing sandalwood into four classes (30, 60, 90, and 100) based on visual observations of the brown heartwood area on the cross-section of the wood sample. The comparative analysis of Sandalwood oil volume indicates variations in oil content among the different classes of Sandalwood wood samples. Sandalwood wood class 90 exhibits a 57.49% Sandalwood oil content compared to class 100. Sandalwood wood class 60 demonstrates a 33.44% Sandalwood oil content compared to class 100. Sandalwood wood class 30 showcases a 19.86% Sandalwood oil content compared to class 100. These findings serve as a reference for determining the pricing of Sandalwood wood as raw material in the Sandalwood oil distillation industry. The price of class 100 serves as the Highest Base Price (Hd), with class 90 priced at 0.5749Hd, class 60 at 0.3344Hd, and class 30 at 0.1986Hd.

Earlier onset and slower heartwood investment in faster-growing trees of African tropical species.

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. 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. 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. 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.

Genotype-Environment Interaction and Horizontal and Vertical Distributions of Heartwood for Acacia melanoxylon R.Br.

Acacia melanoxylon (blackwood) is a valuable wood with excellent-quality heartwood extensively utilized worldwide. The main aim of this study was to confirm the horizontal and vertical variation and provide estimated values of genetic gains and clonal repeatabilities for improving breeding program of A. melanoxylon. Six blackwood clones at 10 years old were analyzed in Heyuan and Baise cities in China. Stem trunk analysis was conducted for sample trees to explore the differences between heartwood and sapwood. The heartwood radius (HR), heartwood area (HA), and heartwood volume (HV) in heartwood properties decreased as tree height (H) in growth traits increased, and the HV = 1.2502 DBH (diameter at breast height)1.7009 model can accurately estimate the heartwood volume. Furthermore, G × E analysis showed that the heritabilities of the eleven indices, including DBH, DGH (diameter at ground height), H, HR, SW (sapwood width), BT (bark thickness), HA, SA (sapwood area), HV, HRP (heartwood radius percentage), HAP (heartwood area percentage), and HVP (heartwood volume percentage) were between 0.94 and 0.99, and repeatabilities of the eleven indices were between 0.74 and 0.91. Clonal repeatability of DBH (0.91), DGH (0.88), and H (0.90) in growth traits, HR (0.90), HVP (0.90), and HV (0.88) in heartwood properties were slightly higher than for SA (0.74), SW (0.75), HAP (0.75), HRP (0.75), and HVP (0.75). These data also implied that the growth characteristics of heartwood and sapwood of blackwood clones were less affected by the environment and had substantial heritability.

Heartwood formation and its relationship with basic density and green moisture content of young small-leaf mahogany trees

Swietenia mahogani (L.) Jacq. is one of Indonesia’s commercially valuable timbers. We investigated the time or age at which heartwood formation begins, and observed and determined whether the occurrence of heartwood formation was affected by age or diameter. The presence of heartwood from the bottom to the top (at various axial positions) of the stem was observed, and the basic density (BD) and green moisture content (GMC) were measured. The area of heartwood and sapwood was determined based on the colour differences in the cross-section. The results showed that the formation of the heartwood begins when the tree is four years old. In the axial position, the heartwood can be found in up to 65% of the tree height. The analysis of variance (ANOVA) test showed that heartwood proportion was determined more by diameter than by age. Therefore this can be a consideration for tree breeding programmes to select trees with larger diameters. Harvesting of young, fast-growing mahogany trees with large diameters from tree breeding can be expected to produce wood with good beauty and durability. Furthermore, BD in the heartwood was lower than in the sapwood, although there was a positive correlation between the proportion of heartwood and BD.

The Methods for Measuring the Area of Heartwood and Sapwood

The presence of heartwood is one of the most important parameters in economic value that can affect the final use of wood. For construction materials, the presence of a large heartwood is very necessary, considering this will have a positive effect on the basic properties of the wood. Meanwhile, its heartwood proportion has a negative impact on the quality of pulp and paper. Therefore, this study aims to review the methods of calculating the area of the heartwood by using suitable heartwood measurement methods for better stand management and selection of raw materials in the industry. The results of the review showed that non-destructive methods were developed to measure the area of heartwood-sapwood such as computer tomography (CT-image), electrical resistivity tomography (ERT), x-ray densitometry, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and near-infrared spectroscopy (NIRS), so far. This is different from the destructive methods that are commonly used for visual inspection of wood color and anatomical features. During the selection of methods, the factors to be considered include cost, time, tree damage, number of samples, and efficiency in applying the methods. The visual inspection is the best option for determining the area of heartwood and sapwood. But, when the heartwood and sapwood boundaries color is unclear, chemical indicators can be performed. In addition, the ERT method can be the second alternative for tropics species. Furthermore, the method used in a study of the presence of heartwood depends on the five limiting factors mentioned previously.

Changes in the intensity of heartwood formation in Scots pine (Pinus sylvestris L.) ontogenesis

Summary An essential stage in woody plant ontogeny (heartwood (HW) formation) determines tree resistance to weather conditions, wood quality (moisture, colour, resistance to biodegradation), and regulates the proportion of functionally active sapwood (SW) in the total trunk biomass. In this study, the patterns of HW formation depending on tree age and cambial age within the same tree were studied in the North-West of Russia in Scots pine in a lingonberry pine forest. It is shown that HW either repeats the trunk profile or shows a maximum proportion on average at the height of 1.5 m. Models using the square root transformation and logarithm transformation have been proposed to predict the number of annual rings in HW depending on the cambial age. Multiple regression is proposed to predict the radial width in HW. Validation of the developed models on random trees gave a good result. HW formation begins at the age of 17–18 years and continues at the rate of 0.3 rings per year for 20–30-year-old trees, 0.4–0.5 rings per year for 70–80-year-old trees, and about 0.7 rings per year for 180-year-old trees. The lifespan of xylem parenchyma cells ranged from 10–15 years in 20-year-old trees to 70 years in 180-year-old trees. At the age of the previous felling (70–80 years) the HW area in the trunk biomass is about 20%, and in 180-year-old pine forests, it increases to 50%. These data can be used to assess the role of old-growth forests in carbon sequestration.

Stem functional traits vary among co-occurring tree species and forest vulnerability to drought

Context Stem functional traits are critical for tree hydraulic infrastructure and have important consequences for forest function, particularly concerning vulnerability to drought. Methods Three stem traits, sapwood area, heartwood area, and bark area, were measured in two co-dominant forest species, Eucalyptus marginata Donn. Ex. Sm. and Corymbia calophylla (Lindl.) K.D.Hill & L.A.S.Johnson, in forest patches with low and high vulnerabilities to drought in south-western Australia. Patches of high drought vulnerability experienced die-off during a heatwave and drought in 2011, while patches of low vulnerability were largely not affected. Key results Sapwood area was significantly higher in C. calophylla than in E. marginata, and C. calophylla maintained more sapwood per unit DBH than did E. marginata, especially in larger trees. There was a 29% smaller sapwood area in high drought-vulnerability patches than in low drought-vulnerability patches (including both species). The relationship between sapwood area and DBH varied by tree size. Small trees had a greater sapwood area in high drought-vulnerable patches, whereas larger trees had more sapwood in low drought-vulnerable patches. It is unclear whether sapwood area relationships reflect differences in leaf area or tree age. Conclusions Observed differences in sapwood between species may help explain their differential tolerance to drought, whereas differences between drought-vulnerability sites may suggest adaptation in the studied species. Implications Understanding the traits associated with drought vulnerability will increase our prediction of forest response to drying and warming. Strong relationships between stem traits and DBH, developed here, may help future efforts to model water-use in the Northern Jarrah Forest.

Compressive strength parallel to grain of earlywood and latewood of yellow pine

The compressive strength parallel to grain of earlywood and latewood from the yellow pine sapwood and heartwood areas was examined in the study. The structure of the basic structural elements of wood - tracheids, which conduct water and/or perform the mechanical function - was also characterized. The compressive strength parallel to grain of latewood in the sapwood area was found to be twice as high as the compressive strength parallel to grain of earlywood. The compressive strength parallel to grain of latewood in the heartwood area, on the other hand, was found to be 2,5 times higher than the compressive strength parallel to grain of earlywood. This was due to the density of particular areas of wood and the dimensions of structural elements - tracheids. In the sapwood area, the density of latewood was ca. twice as high as the density of earlywood. Similar relationships were found for heartwood. The thickness of latewood tracheids was found to be 1,5 times greater than the thickness of earlywood tracheids. These relationships were observed in sapwood and heartwood. The diameter of earlywood tracheids in radial direction was twice as large as the diameter of latewood tracheids. These relationships were observed in yellow pine sapwood and heartwood

Heartwood variations in mid-aged plantations of Erythrophleum fordii

Erythrophleum fordii Oliv. (Caesalpiniaceae) is a rosewood species naturally distributed in southeast Asia and south China, and the heartwood is commonly used for high-quality crafts and furniture. While there are differences in heartwood development among single trees with distinct social status, the relationship between heartwood development and growth performance remains unclear. This information is essential to improve plantation management for high-yield heartwood production. Forty dominant, intermediate and suppressed trees were sampled from E. fordii plantations aged in 32–35 years in Pingxiang City, Guangxi, China. Stem analysis was carried out to determine horizontal and vertical variations of heartwood and sapwood. Number of annual rings, diameter and area of heartwood and sapwood as well as ratios of heartwood diameter and area at breast height were all significantly influenced by the social status of trees in stands (P < 0.05). In these mid-aged plantations, E. fordii stems developed heartwood once the xylem diameter reached 5–10 cm, and then heartwood diameter and area increased with increasing xylem diameter. Heartwood ring numbers, diameter and area as well as their ratios decreased with increasing height, while sapwood ring numbers and diameter were relatively constant within the section where heartwood occurred. Heartwood and sapwood diameters were equal at heights of approximately 6-m for dominant, 5-m for intermediate and 3-m for suppressed trees. Dominant trees differed considerably from intermediate and suppressed trees in heartwood volume, while heartwood volume ratios were all below 30%, and near 90% in the stem section below 8-m height regardless of social status. Relationship analysis showed that DBH was the most important factor influencing heartwood in even-aged stands. The findings provide evidence for crop tree selection, thinning regimes and reasonable management of plantations of E. fordii.

Disentangling the role of competition, light interception, and functional traits in tree growth rate variation in South Asian tropical moist forests

Tropical forests have been focused for mitigating climate change impact through carbon sequestration in plant biomass under clean development mechanism (CDM). Since trees represent more than 98% of the above ground plant biomass, variation in tree growth rate drives carbon dynamics in tropical forests. By using tree-ring analysis, trait-based measurements, and field observations, we aimed at understanding the drivers of growth rate variation in four South Asian tropical moist forest tree species varying in plant functional types. Principal component analysis (PCA) revealed that mainly demographic and wood traits represented the first axis explaining 37% of the variance, whereas the second axis was represented by the leaf traits. Stem growth rate (DI) showed a nonlinear negative relation with competition index (CI) and the ratio of crown surface area to basal area (CBR) in three out of four tree species (p < 0.001) except Lagerstroemia speciosa which showed no significant relationship with any of the studied variables. DI was linearly positively related with light interception index (LI) and the ratio of sapwood area to heartwood area (SHR) in the shade intolerant Magnolia champaca and Toona ciliata (p < 0.001). Sap wood area (SA) had a strong positive effect on DI in the three species (p < 0.001). Taking tree size as a random factor and thus accounting for ontogenetic effects on tree growth, linear mixed effect modelling revealed that CI, SA and SHR are the best predictors of DI in M. champaca (AIC = 25.81, R2m = 0.81) and T. ciliata (AIC = 62.95, R2m = 0.61). In C. tabularis, CI, SA and CBR included in the best model predicting DI (AIC = 94.62, R2m = 0.55). Variance partitioning analysis showed that the highest pure effect was observed in C. tabularis contributed by CI (12%), while the highest joint effect was found in M. champaca contributed by CI, SA and SHR (40%). Our analyses suggest that competition by neighbouring trees especially for soil moisture and the amount of active xylem portion are the main drivers of tree growth in moist tropical forests. Since tree growth rates regulate forest carbon dynamics, the insights into the growth drivers of the four selected species revealed by the study have important implications for forest/plantation management with a focus on carbon storage under CDM.

On the fluid permeability of heat treated paulownia wood

ABSTRACTFibre direction cylindrical specimens from the sapwood and heartwood areas of Paulownia wood were heat treated at 180, 190, and 200°C split in eight groups of ten specimens each. Air and water permeability were measured, thereafter. Results demonstrated that heat treatment had a positive effect on air permeability both in sapwood and heartwood specimens. That increase might be attributed to the development of cell wall micro-checks caused by thermal degradation and fracture of the vessel tyloses. Liquid permeability was significantly decreased as a result of heat treatment.

Change pattern of heartwood of Larix olgensis plantation.

Based on the data of 1179 discs and whorls of 49 trees from larch (Larix olgensis) plantations located in Mengjiagang forest farm in Heilongjiang Province, China, we analyzed the longitudinal variation pattern of heartwood radius. The results showed that the heartwood radius decreased with the increases of tree height, which was basically the same as the trunk shape. The relationship between the xylem radius (XR), diameter at breast height (DBH) and cambial age (CA) with the heartwood radius was significant. The stepwise regression analysis was used to develop heartwood radius (HR) and heartwood area (HA) models: HR=b1+b2XR2+b3CA+b4XR, HA=b1+b2DBH·XR+b3CA+b4DBH·XR2. We used the evaluation statistics such as AIC, BIC, Log Likelihood and Likelihood ratio test to compare the heartwood radius and heartwood area models which fitted with the plot effect and tree effect. The heartwood radius and heartwood area models with parameters b1, b2, b3 as mixed effects performed best when the tree effect was considered. The prediction accuracy of the mixed model was better than that of the basic model. In the application, the total heartwood radius and area could be predicted by the mixed model. Beta regression model was used to simulate the heartwood proportion. In this model, all parameters were significant, and the coefficients of determination were relatively high, with a good simulation effect.

Heartwood/sapwood profile and the tradeoff between trunk and crown increment in a natural forest: the case study of a tropical tree (Dicorynia guianensis Amsh., Fabaceae)

Sapwood area and the radial growth rate of the trunk follow the same pattern at breast height, with an initial increase and subsequent constant value, resulting from the increasing growth allocation toward the crown rather than tree decline. Heartwood area and heartwood volume in the trunk increase more rapidly after this shift occurs. Sapwood (SW) and heartwood (HW) are two functionally distinct classifications of wood in perennial stems for which quantities can vary greatly in tropical trees. Numerous positive correlations have been found between the radial growth rate (RGR) and SW quantity; however, variations in the SW/HW quantities have not been studied in light of the ontogenetic variation of RGR. Wood core sampling, intensive measurements of tree structure (number of branches, stem volumes), and radial growth monitoring were performed on an abundant and highly exploited tree species in French Guiana (Dicorynia guianensis) to investigate the relationship between RGR, SW/HW quantity, tree structure, and their variations on the course of a tree’s ontogeny. SW area and RGR followed the same pattern of variation throughout tree development, both increasing first and reaching a steady state after 50 cm DBH (diameter at breast height). After this value, we observed a strong increase in both the HW area and HW volume increment, concomitant with a more rapid increase in crown volume. The stabilization of RGR for trees with DBH > 50 cm was related not to a tree’s decline but rather to an increasing wood allocation to the crown, confirming that RGR at breast height is a poor indicator of whole-tree growth for bigger individuals. We also confirmed that HW formation is an ontogenetic process managing SW quantity that is continuously and increasingly produced within the crown as the tree grows. This study highlights the effect of growth-mediated ontogenetic changes on the localization of water and carbohydrate storage within a tree, resulting from SW and HW dynamics throughout tree ontogeny.

Two New Zealand-based common garden experiments of the range-wide ‘Kuser’ clonal collection of Sequoia sempervirens reveal patterns of provenance variation in growth and wood properties

Sequoia sempervirens (Coast redwood (Lamb. ex D. Don) Endl.) plantings in New Zealand are increasing due to favourable growth rates. There is, however, very limited information on S. sempervirens genetics on which to build breeding and deployment decisions. In this study we present results from the assessment of growth, wood density, heartwood area, and epicormic shoots in two replicated clonal provenance trials of 170 S. sempervirens clones at two sites. Across-site genetic correlations among provenance for traits were high, 0.9 or above, with the exception of 0.7 for epicormic shoots. Medium-to-high genetic control was expressed for all growth and wood property traits. Broad-sense heritabilities for the two sites assessed were: diameter at breast height (1.4 m) (0.35 and 0.52), wood density (0.52 and 0.30), and percentage heartwood (0.40 and 0.50). Epicormic shoots were under low genetic control (0.11 and 0.27) and may be more influenced by the environment. Genetic correlations between traits showed that growth rate was negatively correlated with wood density (−0.52 to −0.58). Faster growth was also correlated with more epicormic shoots (0.36–0.44). We found no strong trends between growth performance, provenance location, or provenance site characteristics of the material tested. In contrast to earlier research in the United States of America, this study found a high clonal repeatability for the above traits and it demonstrated a low genotype × environment interaction. This study provides important and new insights in the genetic variability of S. sempervirens provenances.

Simulating the heartwood formation process of Erythrophleum fordii in South China

We studied the formation of heartwood in Erythrophleum fordii Oliv., an endangered rosewood species, by cross-section analysis on 52 stumps aged 28–57 years and arbitrarily sampled from natural forests in South China. Width and area of heartwood were positively correlated with age and xylem width (XW), and were independent of annual radial growth. The proportions of heartwood and sapwood areas were equal at about 40 years. The heartwood formation process was simulated by linear regression of age and XW.

Structural development of redwood branches and its effects on wood growth

Redwood branches provide all the carbohydrates for the most carbon-heavy forests on Earth, and recent whole-tree measurements have quantified trunk growth rates associated with complete branch inventories. Providing all of a tree's photosynthetic capacity, branches represent an increasing proportion of total aboveground wood production as trees enlarge. To examine branch development and its effects on wood volume growth, we dissected 31 branches from eight Sequoia sempervirens (D. Don) Endl. and seven Sequoiadendron giganteum Lindl. trees. The cambium-area-to-leaf-area ratio was maintained with size and age but increased with light availability, whereas the heartwood-deposition-area-to-leaf-area ratio increased with size and age but was insensitive to light availability. The proportion of foliage mass arrayed in <1-cm-diameter epicormic shoots increased with decreasing light and was higher in Sequoia (20-60%) than in Sequoiadendron (3-16%). Well-illuminated branches concentrated leaves higher and distally, while shaded branches distributed leaves lower and proximally. In similar light environments, older branches distributed leaves lower and more proximally than younger branches. Branch size, light, species, heartwood area, a heartwood-area-species interaction, and ovulate cone mass predicted 87.5% of the variability in wood volume growth of branches. After accounting for the positive effects of size and light, wood volume growth declined with heartwood area and age. The effect of age was trivial compared to the effect of heartwood area, suggesting that heartwood expansion caused the age-related decline in wood volume growth. Additionally, Sequoiadendron branches of similar size and light environment with more ovulate cones produced less wood, even though these cones were long-lived and photosynthetic, reflecting the energetic cost of seed production. These results contributed to a conceptual model of branch development in which light availability, injury, heartwood content, gravity, and time interact to produce the high degree of branch structural variation evident within redwood crowns.

Relationship of heartwood traits with diameter growth, implications for genetic selection in Pinus radiata

The heartwood of radiata pine (Pinus radiata D. Don) is not favoured commercially because of its darker appearance, unreliable durability and difficulty to treat chemically; consequently, light-coloured sapwood, which is more easily treated with decay-resistant chemicals, is of more value. To decrease the amount of heartwood or increase sapwood cross-sectional area by genetic selection, the genetics of sapwood cross-sectional area (SWA), sapwood area percentage (SWAP) and number of heartwood rings (HWR) is of interest. We investigated genetic variation in these three variables from increment cores from trees from two trial series, each planted at two sites, from a total of some 330 families (189 were half-sib and 142 were full-sib) with 10 to 30 individuals assessed per family. Trials were assessed between 16 and 23 years old when all trees had started to develop heartwood. The three sapwood-related traits were moderately heritable across pairs of sites (\( {\widehat{h}}_i^2 \) = 0.2 to 0.4) indicating opportunity for selection. SWA was strongly correlated (ra = 0.9) with diameter. SWAP and HWR were also strongly correlated (ra = −0.9). The number of HWR was independent of tree diameter, providing the opportunity through genetic selection to reduce heartwood area whilst increasing tree growth rate.

Heartwood stump colonisation by Heterobasidion parviporum and H. annosum s.s. in Norway spruce (Picea abies) stands

Stump-to-tree spread is a key step in the root and butt-rot disease caused by Heterobasidion annosum sensu lato. In Norway spruce stands, Heterobasidion parviporum is more likely to spread to neighbouring trees from stumps with a large diameter than from small stumps. However, H. annosum sensu stricto does not appear to share this pattern of infection. Given that the ratio of heartwood to sapwood varies depending on the size of the stump, we investigated the role of heartwood and sapwood in stump infection by H. parviporum and H. annosum s.s. To determine whether heartwood–sapwood susceptibility was different in different host species, both Norway spruce and Scots pine stumps were included in the study. Sapwood, heartwood and the border zone between sapwood and heartwood of spruce stumps and the heartwood and sapwood of pine stumps were artificially inoculated with different genotypes of H. annosum s.s. and H. parviporum. Only one zone was inoculated per stump. Infection was assessed 2 and 10months after inoculation at 5 and 30cm below the point of inoculation. On spruce stumps, H. parviporum and H. annosum s.s. were mostly confined to the heartwood. The area infected by H. annosum s.s. was smaller than that infected by H. parviporum. Both sapwood and border infections tended to grow towards the heartwood, whereas heartwood inoculations tended to remain in the heartwood, indicating that heartwood was more favourable for H. parviporum and H. annosum s.s. colonisation in spruce stumps. On pine, heartwood colonisation failed and only H. annosum s.s. was found in the sapwood. Our results suggest a possible association between the size of the stump and the spread of H. annosum s.s. to neighbouring trees mediated by the heartwood content, suggesting that screening for heartwood resistance could be a potentially interesting direction for future research. Treating stumps at final felling would be advisable owing to the large area of heartwood exposed by this operation.

Frequency of False Heartwood of Stems of Poplar Growing on Farmland in Sweden

Swedish owners of poplar stands are interested in both the wood quality and the use of poplars that are soon to be harvested. An important concern is the frequency of false heartwood (FHW) in the stems. We have presented an overview of the factors causing discolored wood as well as the industrial use and quality of the end products. We have studied poplar stems growing at 22 sites in Sweden between latitudes 55° N and 60° N. The mean age of the poplar was 23 years (range 14–41), the mean stand density 1011 stems ha−1 (range 155–3493) and the diameter at breast height (DBH) (over bark) 246 mm (range 121–447). All stands were growing on clay soils (light and medium clay and light clay tills). All of the sampled stems (42) contained false heartwood. At 0%–50% of stem height, all sampled trees were discolored and at 90% of stem height, 33% were discolored. The percentage of false heartwood area by stem area was highest at 1% and 10% of stem height (26.6% and 24.7% respectively). The “FHW” part of the stem had a radius of 47 mm (range 9–93) at 30% of stem height, which corresponds to 50% of the total stem radius. A log of six meters represents about 30% of stem height. Equations describing the correlation between DBH and the diameter of FHW at different stem heights (1%, 10%, 30%, 50%, 70% and 90%) and table describing FHW volume % by total stem volume at the first 50% of stem height were constructed. These might be helpful for estimating the percentage of fresh wood in a stem. However, most of the fast-growing poplars will be harvested as biofuel.

Estimated heartwood weights and oil concentrations within 16-year-old Indian sandalwood (Santalum album) trees planted near Kununurra, Western Australia

Summary Thirty-two Indian sandalwood (Santalum album) trees aged 16 y, growing near Kununurra (Western Australia), were harvested, de-barked and weighed to determine their commercial wood (heartwood and sapwood) weights. Within each tree, heartwood area, percentage and weight were measured in stem cross-sections at five different heights (0, 0.50, 1.00, 2.00 and 3.00 m above the ground) in the main stem, and used to estimate total heartwood volume and weight. Heartwood oil concentration and a—and β-santalol concentrations were also measured at the same heights in each tree. At age 16 y, the 32 S. album trees had mean estimated air-dry weights (at ~12% moisture content) of 5.8 kg heartwood tree−1 and 43.7 kg sapwood tree−1. The mean air-dry wood densities were 940 kg m−3 for the heartwood and 840 kg m~3 for the sapwood. Estimated heartwood weight was variable between trees, with the three largest trees each containing 24–30 kg heartwood, while nine other trees each had 0–1 kg heartwood. The S. album plantation in this study contained about 260 trees ha −1, and its predicted yields (air-dry weight) at age 16 y were 1.5 t heartwood ha−1 and 11.41 sapwood ha −1. Within each tree, the mean oil concentration (w/w air dry) ranged from 6.2% (at 0 m) to 2.9% (at 3.00 m). Overall, the mean oil concentration within the heartwood was 5.0%, giving estimated yields of 0.28 kg oil tree−1 and 73 kg oil ha−1 (based on 260 trees ha−1). The mean α-santalol concentration (44–50%) and β-santalol concentration (18–20%) at the five different tree heights met the current ISO standard for S. album oil. In the 16-y-old S. album trees, over-bark stem diameter at 300 mm above the ground correlated well to both total air-dry weight of wood (heartwood and sapwood) per tree (r2 = 0.88) and heartwood air-dry weight per tree (r2 = 0.87). This indicated that large-diameter trees had markedly higher heartwood weights.