Proportion Of Sapwood Research Articles

Fuel Wood Pellets Produced from Sawdust of Scots Pine Mature and Juvenile Wood: Self-Heating and Off-Gassing Tests at Industrial Scale

This study investigated self-heating and off-gassing of Scots pine (Pinus sylvestris) wood pellets made from sawdust generated from separated mature and juvenile wood. The pellets were produced at an industrial scale and stored in large piles of about 7.2 tonnes. The production process involved drying the sawdust using three different methods and to varying moisture contents. The results indicated significant influences of both raw material type (F(6) = 61.97, p < 0.05) and drying method (F(2) = 65.38, p < 0.05) on the self-heating of the pellets. The results from the multiple regression analysis further showed that both the raw material type and pellet moisture content significantly influenced the temperature increase, with strong correlations observed for pellets produced using low-temperature drying (F(3, 14) = 83.52, multiple R2 = 0.95, p < 0.05), and medium temperature drying (F(3, 13) = 62.05, multiple R2 = 0.93, p < 0.05). The pellets produced from fresh mature wood sawdust were found to be more prone to self-heating and off-gassing while steam drying the sawdust at high temperature and pressure led to a significant reduction in heat and gas generation across all materials. The heightened self-heating and off-gassing in mature wood pellet can be attributed to a higher proportion of sapwood in the raw material. The probable explanations to the observed differences are in line with biological mechanisms for self-heating and off-gassing, as well as the chemical oxidation of fatty and resin acids.

Differences of technological properties on sapwood and heartwood of short rotation teak wood

ABSTRACT Short rotation teak has been developed to overcome the limited supply of long rotation teak. The characteristics and technological properties of sapwood and heartwood of short rotation teak are not well studied. The purpose of this study was to evaluate the effect of sapwood and heartwood differences on technological properties for short rotation teak. The short rotation teak woods used were Plus Perhutani teak of 15 years old with a sapwood proportion of 30% and Biotrop teak of 8 years old with a sapwood proportion of 18%. The following technological properties of sapwood and heartwood were studied: extractive content, chemical composition, volumetric swelling, water-sorption isotherm, modulus of elasticity, modulus of rupture, decay resistance, termite resistance, surface roughness, surface free energy, wettability, and weathering performance. The results showed that the extractive content of heartwood was higher than sapwood. The main compounds in the extractive content of heartwood were lapachol and 9,10-anthracenedione; meanwhile the main compounds of sapwood were mostly single sugars and derivatives. The extractives present could contribute to technological properties of short rotation teak wood, particularly for improved dimensional stability, reduced water-sorption, higher decay and termite resistance, and better photostability. Sapwood presented lower quality especially in dimensional stability and durability, which could restrict its utilization for both indoor and outdoor applications. Therefore, sapwood should require certain treatments, especially for wood exposed to outdoor conditions.

Characteristics and intrinsic influencing factors of log humification depend on wood traits in a subalpine forest

Deadwood is an indispensable component of forest ecosystems, with important consequences for global carbon cycling. Although research into carbon release from decaying logs and its response to wood traits has increased, little attention has been paid to how wood traits affect the potential of carbon sequestration in decaying logs through humification. To evaluate the wood trait effects, we measured the concentrations (mg g−1) and content (mg cm−3) of humus, including humic substrates, humic acid, and fulvic acid, and the degree of humification (%) separately in bark, sapwood, and heartwood in a four-year log decomposition experiment in a subalpine Minjiang fir forest on the eastern Qinghai-Tibet Plateau, China. We found the highest humus concentrations and humification degree in bark and the lowest in sapwood. The humus mass had a net loss in bark and did not change in sapwood over time. As decomposition proceeded, the humus mass in heartwood firstly accumulated and then decreased. In addition, wood traits strongly affected the humification of sapwood and heartwood compared to bark. Lignin and its interactions with cellulose and N concentrations were associated with sapwood humification. Nutrient conditions like N and P concentrations and the C/N ratio were related to heartwood humification. These findings suggest that wood traits can determine the potential of carbon sequestration of decaying logs through humification and that the large proportion of sapwood in decaying logs has a positive effect on long-term and stable carbon sequestration in poor soils in subalpine forests.

Balsam Fir (Abies balsamea (L.) Mill.) Wood Quality after Defoliation by Spruce Budworm (Choristoneura fumiferana Clem.) in the Boreal Forest of Quebec, Canada

Eastern spruce budworm (Choristoneura fumiferana Clem.) is considered the most important disturbing insect in coniferous stands in eastern North America. During an outbreak, spruce budworm can cause severe defoliation in balsam fir (Abies balsamea (L.) Mill.), which can affect wood properties such as moisture content and mechanical properties. This project aimed to assess the influence of the duration of spruce budworm defoliation on the wood quality of mature balsam fir trees. To do this, we studied sapwood proportion, decay, moisture content, mechanical properties and tracheid dimensions in stands that had suffered three, four or five years of defoliation. We also compared living and dead balsam firs and evaluated the change in wood properties with time. Our results showed that dead balsam firs suffered from a loss of wood quality rapidly after their death, particularly in terms of moisture content and decay in the sapwood. Sapwood proportion was similar between living and dead trees, but the sapwood of dead trees contained more decay and had a lower moisture content than living trees. Mechanical properties and tracheid dimensions were 10% and 4% lower in dead trees than in living trees. We did not observe any major differences in wood properties between the three durations of defoliation, suggesting that wood degradation occurs before that. The study did not make it possible to determine the optimal duration of defoliation to harvest the stands.

Evaluation of Selected Physical Properties of Blighia sapida K. Koenig Wood

Blighia sapida, a Lesser-Used Species is being processed into sawn timber to meet the demand for wood. The knowledge of its wood quality would enhance its effective utilization. However, there is little information known on the physical properties of this species that could enhance its acceptability and optimum utilization. This, therefore, necessitate the need to investigate the physical properties of this wood species.&#x0D; Three standing trees of B. sapida were purposively felled for this study. Billets of 500 mm were obtained from the wood disc at the base, middle, and top of the tree. Each wood disc was partitioned into three; innerwood, middlewood, and outerwood following specified international standards for the physical properties test (wood colour, proportion of sapwood and heartwood, bark thickness, density, moisture content, and volumetric shrinkage).&#x0D; B. sapida wood density with a mean value of 709.78±8.88 kg/m3, ranged from (571.59±13.45 to 854.81±7.08 kg/m3. Moisture content percentage of average value 70.62±1.23%, ranged from 53.84±1.40 to 89.00±2.75%. Volumetric shrinkage of average value 15.24±0.25%, range from 13.38±0.66 to 16.89±0.83%. The range of B. sapida wood density value of the study falls within the range that could be categorized as medium density wood of medium construction strength properties. The 1:1.5% tangential–radial shrinkage observed in this study was low, an indicator of a low risk of deformation while seasoning the wood, as the ratios of tangential-radial shrinkage that is high are those over 2.2%.

Woodland Management Practices in Bronze Age, Bruszczewo, Poland

The article presents a study of wood excavated from archaeological site in Poland (2100–1650 BC). The large amount of collected samples created a unique opportunity for research because the subfossil wood was in very good preservation state. This made it possible to carry out dendrotypological analysis. This is the first such study conducted for Early Bronze Age timber originating from Poland. The main goal of the study was to determine whether the presence of strong and abrupt reductions and releases of growth, observed within tree-ring sequences, is due to natural stand dynamics, results from the influence of extreme environmental factors or whether they should be linked to specific silvicultural practices already known in ancient times. Another purpose of the study was to determine the type of forest management techniques applied to the trees growing in Bruszczewo site. The research was conducted using the dendrochronological method. In addition to the measurements of growth-ring width, the development of earlywood and latewood zones, the proportion of sapwood and the presence of specific features of tree trunks were analysed. A detailed study allowed identifying the samples originating from coppiced and shredded trees. A characteristic feature of the trees subjected to these silvicultural practices is the presence of strong and abrupt reductions and releases of growth. Moreover, coppiced trees were specified by the large proportion of sapwood in the cross-section of the stem, reduced number of sapwood rings, small and numerous earlywood vessels, diminished earlywood vessels area. In turn, shredded trees distinguished themselves by a strong reduction in the earlywood width in the years following the shredding event. The research of archaeological wood from the ancient settlement proves that during the Early Bronze Age various forest management techniques were used in this site. These treatments were aimed at improving the quality and quantity of the raw material harvested from forest areas.

SOME OF PHENOTYPIC, PHYSICAL AND ANATOMICAL WOOD PROPERTIES OF VALONIA OAK TREES IN KURDISTAN-IRAQ

This study was aimed to investigate the morphologic, macroscopic, and microscopic description with the paper pulp quality index was determined to facilitate its increased use and to analyze the variation of wood properties. Among different morphological characteristics Q. aegilops registered mean height (13.63 m) and diameter (26.04 cm), while bark thickness represented from 7.2 to 15.6mm. Average bark and wood percent was noticed (8.22%) and (91.78%) of the total volume, with annual ring growth width (3.17mm) that considered a slow-growing species. The highest heartwood proportion of stem volume was 75.32% and the lowest 42.01% with a mean of 61.46%. The sapwood proportion ranged between 23.68 and 57.99% with a mean of 38.54%. While the values of anatomical properties were: The mean values of fiber length, fiber diameter, double cell wall thickness, and fiber lumen width were 1.01mm, 15.54µm, 6.288µm, and 9.25µm respectively. Moreover, the mean values of vessel length and vessel diameters were 0.54mm and 179.80µm respectively. Significant differences were found in the pulpwood quality indices for the paper samples, the means value of the runkel index was 0.86, while, slenderness index was 68.84, the coefficient of flexibility was 0.57, and the average value of the stiffness coefficient was 0.421. The fibers length more than1mm and cell well is thick accordingly are classified as good for paper. Based on its morphological and physical properties, Q. aegilops wood can be used in various wood manufactures. Based on the anatomical properties and pulp quality indices, this wood could be used to obtain cellulose pulp for paper production.

PHYSICAL PROPERTIES AND PRESERVATIVE TREATMENT OF EUCALYPTUS AND CORYMBIA WOOD

The properties of wood influence its use as a final product, so it is essential to know their relation and influence on the quality of preservation. In this sense, for the present study we aim at the determination of the physical properties of Corymbia citriodora [Eucalyptus citriodora Hook]; Eucalyptus camaldulensis Dehnh. and Eucalyptus camaldulensis Dehn. x Eucalyptus grandis, and the quality of the preservative treatment with CCA-C in an autoclave. We determined diameter, heartwood and sapwood percentages, and their relationship, as well as the basic density for the three genetic materials. The quality of the preservation was evaluated through the area treated and not treated by CCA, besides its penetration and retention. The highest proportion of sapwood, treated area, and highest density value was found in C. citriodora, whereas the hybrid E. camaldulensis x E. grandis presented the highest level of CCA retention. The diameter and density showed the highest correlation with CCA retention in wood, the length and moisture of the small logs also shown to be influential. All clones presented satisfactory chemical treatment quality for use as fence posts.

Influence of wood’s anatomical and resin traits on the radial permeability of the hybrid pine (Pinus elliottii × Pinus caribaea) wood in Australia

Wood permeability has a major effect on industrial wood processing and utilization. Wood anatomy and resin influence the permeability of wood. Understanding and manipulating these influences is important to optimize the manufacture and use of forest products. This study investigated the relationships between wood anatomical traits, radial permeability, and resin content of samples collected from 19-year-old hybrid pines (Pinus elliottii var. elliottii × Pinus caribaea var. hondurensis) from Queensland, Australia. The earlywood tracheid tangential lumen diameter and axial resin canal diameter were statistically positively correlated with radial permeability. The heartwood proportion and the frequency of axial resin canals were statistically negatively correlated with radial permeability and positively correlated with resin content. The axial resin canal diameter, sapwood proportion, latewood content, ray frequency, and earlywood tracheid lumen diameter increased from pith to bark, whereas the axial resin canal frequency decreased. Resin was found distributed throughout the wood microstructure, from pith to bark in many samples, and in both heartwood and sapwood. However, there was a much greater quantity of resin in heartwood and wood from the middle (inner radius) of the tree, with widespread occurrence of resin impregnation in the axial tracheids.

Determination of elastic properties of latewood and earlywood by digital image analysis technique

The proportion of latewood varies from species to species and from site to site. To understand the stiffness of wood structures, it is necessary to accurately determine the modulus of elasticity (MOE) of the wood. In this paper, a digital image correlation method was used to analyze the surface strain of wood specimens during tensile testing and calculate the Poisson’s ratios of latewood and earlywood. Digital image analysis (DIA) and X-ray densitometry (XrD) techniques were employed to determine the latewood proportion. Good agreement was observed between the DIA and XrD results for the sapwood proportion. Based on the rule of mixtures, the effective MOE was calculated based on the MOEs of earlywood and latewood.

Physical and anatomical properties: the case of two progenies of Melia dubia Cav

Two progenies of Melia dubia plantation of six year old were selected for studies on physical and anatomical properties of wood. Data for each selected trees progenies selected were recorded for height, clear bole length, diameter at breast height, initial moisture content, specific gravity and sapwood proportion. Macroscopic features were observed and recorded under 10 x lenses. Slides were prepared for microscopic views of the wood in three directions viz. pith, middle and periphery. Maceration was done as per Schultze's method to prepare slides for studies on fiber and vessel morphology of the wood samples. The analysis revealed that wood of M. dubia showed distinct growth rings, the sapwood was yellowish white in colour, the heartwood was yellowish brown in colour. The mean moisture content in the living trees was recorded to be 80.3%. The specific gravities of selected progenies were 0.43 and 0.35. The difference in specific gravities between the progenies was statistically significant. Mean sapwood % in both the progenies was 39.12 %. While the mean fiber length was 716.72µm, mean fiber wall thickness was 4.15µm. Mean vessel length of the progenies was 260.5 µm. Significant variability in physical and mechanical properties of wood, indicates a need of careful tree breeding programme for the species.

Wood density is a poor predictor of competitive ability among individuals of the same species

Competition between immediate neighbors has been regarded as one of the most important forces of natural selection that shapes the species composition, diversity and evolution of plant traits within a community. Here, I examined wood density (WD) variation in populations of two tree species, where individuals have contrasting access to resources. In five Nothofagus betuloides and Nothofagus pumilio even-aged, mixed second-growth forests in Patagonia (Chile), I sampled pairs of dominant (full access to resources) and the nearest-to-it suppressed individuals (constrained access to resources), with the following main objective: to assess whether WD is a good predictor of the competitive ability of individuals in tree populations. To accomplish this objective, I quantified, at the individual level, sapwood (WDsap) and heartwood densities (WDheart), sapwood proportion (Sapp), growth rates (BAI10) and growth efficiency (GE). Given that sapwood and heartwood differ in functionality, I used WDst, a standardized way of computing WD that considers both wood type proportions in the stem. In order to determine the relationship between growth rate (BAI10, a proxy of competitive ability) and WD at the intraspecific level, I analyzed the effect of contrasting access to resources (dominant versus suppressed individuals) and WD fitting mixed-effects correlation models (LMM). WDst showed very low variation (<6% of CV), and WDst did not differ between dominant and suppressed individuals for both species, nor did Sapp. Dominant individuals of both species had significantly higher BAI10 and GE values than suppressed individuals. I found a non-significant correlation between BAI10 and WDst. Independently of tree species and access to resources, WDheart was significantly higher than WDsap. In conclusion, my results are unequivocal in that WD is a poor predictor of competitive ability among individuals of the same species and thus interspecific trends found in the growth–WD relationship are not paralleled at the intraspecific level.

Electrical impedance tomography for decay diagnostics of Norway spruce (&lt;i&gt;Picea abies&lt;/i&gt;): possibilities and opportunities

The paper aimed at testing the potential of refining tree rot diagnostics carried out by means of electrical impedance tomography (EIT). Examined was the use of EIT datasets with electrical resistance values and sapwood proportion determined on the basis of tomograms. Making use of datasets with resistance values in EIT rot diagnostics is not a default method, although datasets stay unaffected by a fixed colour scale and subsequent subjective evaluation unlike tomograms. Tomography measurement was carried out for 27 individuals of Norway spruce ([L.] Karst.) in two stands north-east of Brno, Czech Republic. Once felled down, radial cut-outs were sampled at the measurement site and used for localising rot and determining the extent of the area of decay. The results were subsequently compared with tomograms. EIT datasets containing values of electrical resistance found by measuring were statistically processed and compared with the extent of rot area identified within the cuts. Sapwood proportion values were also detected using the tomograms. The baseline assumption that sapwood proportion decreases as the rot area in the radial cut expands was confirmed. In trees with rot percentage to 35% approximately, sapwood proportion was exceeding 30% except one tree. In trees with rot percentage exceeding 35%, sapwood proportion was below 30%. On the basis of interpreted datasets, the trees can be split into three characteristic groups that correspond to the occurrence, extent and nature of the rot.Picea abies

Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid (Eucalyptus grandis × E. urophylla) clones

We studied two clones of Eucalypturograndis hybrid (Eucalyptus grandis × E. urophylla), GR283 and GR330, grown in Tumkur district of Karnataka (India), and felled 5–6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood including fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 (37 %). Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be utilized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.

Évolution des proportions d’aubier et de duramen du cèdre de l’Atlas, Cedrus atlantica Manetti, en Algérie

L’étude a été conduite dans les cédraies du Bélezma (Aurès), du Djurdjura (Kabylie) et de Theniet El Had (Oranie), contrastées du point de vue bioclimatique et altitudinal. Elle s’inscrit dans le cadre global du projet sur le fonctionnement des cédraies algé- riennes. La problématique de l’étude est liée à l’absence de données sur le pro- cessus de duraminisation chez le cèdre de l’Atlas, données pourtant très utiles pour approfondir les connaissances sur la typologie des peuplements de cèdre. L’objectif était de mettre en évidence, dans un premier temps, l’évolution spa- tio-temporelle de la duraminisation. Sur l’ensemble des trois cédraies, 485 ron- delles et carottes de bois ont été analysées. Les résultats montrent la faible variation des proportions du duramen d’une station à l’autre au sein d’une même cédraie. Globalement, l’âge affecte positivement la formation du duramen et négativement la proportion l’aubier. L’initiation de la duraminisation apparaît plus précoce dans les cédraies de Theniet El Had et Djurdjura (14 à 17 ans) et tardive dans les Aurès (20 à 30 ans). Dans cette dernière localité, le cèdre se singularise par une faible pro- portion d’aubier, variant de 45 % à 50 %. Dans tous les cas, la cédraie du Djurdjura, située dans le bioclimat le plus humide, se distingue des deux autres cédraies par ses faibles proportions de duramen et fortes proportions d’aubier, respectivement 44 % et 56 %. Le classement établi pour les proportions maximales d’aubier met au premier rang la cédraie de Talla Guillef dont la proportion d’aubier est de 78 % et en dernier la cédraie du Bélezma avec un taux moyen de 68 %. Il se dégage de ce fait une tendance à l’évolution des pro- portions d’aubier en fonction du gradient bioclimatique en allant du perhumide au semi-aride. En outre, l’étude met en évi- dence la très faible proportion de l’aubier chez les arbres dépérissants, avec une valeur moyenne de 46 %.

Heartwood, sapwood and bark content of teak trees grown in Karnataka, India

We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Karnataka covering different age groups (11–36 years), density (516–2061 trees/ha) and sites. From these plantations, a total of 130 trees were felled for estimating the yield and bark content in relation to diameter at breast height (DBH), age and density. Bark content ranged from 22.2%–54.3%. Heartwood and sapwood content were analyzed by sampling five trees each from two different plantations, one 30 years old at 553 trees·ha−1 and the other 32 years old at 911 trees·ha−1. The highest heartwood proportion of stem wood volume (over-bark) was 56.3% and the lowest was 37.1%. The sapwood proportion ranged from 12.9%–23.0%, while the bark content ranged from 27.8%–43.5%. The heartwood proportion increased with DBH, while the proportion of bark decreased. The sapwood proportion did not vary with DBH. The bark content decreased with increasing age, but increased with stand density. There was no significant difference in heartwood content with respect to age or stand density because the ages of the two stands were similar. A larger dataset from young to mature stands is needed to describe the relationships between age and stand density and heartwood, sapwood and bark content of trees.

Variation of Brown Rot Decay in Eastern White Cedar (Thuja occidentalis L.)

Variations in brown rot decay and proportions of heartwood and sapwood were investigated in eastern white cedar (Thuja occidentalis L.). This experiment tested the hypothesis that the incidence of brown rot decay depends on the site, tree age, tree height, and heartwood/ sapwood ratio. Forty-five trees were sampled and felled from three mature stands in the Abitibi-Temiscamingue region, Quebec, Canada. From each tree, disks were systematically sampled along the entire stem, and the heartwood, sapwood, and decay proportions and volumes were determined for each disk. Scanning electron microscopy showed that growth of fungi causing brown rot decay was limited and slower in latewood than in earlywood due to the narrow cell lumen, thick wall, and limited number of bordered pits in latewood tracheids. Site, tree height, and tree age had significant effects on the proportions of sapwood, heartwood, and decay. Heartwood and brown rot decay proportions decreased from the base of the tree upward, while the sapwood proportion increased. There was more decay in older trees and in those growing on moist versus dry sites; however, decay was not serious in trees younger than 80 years. In addition, brown rot decay proportion correlated strongly and positively with heartwood proportion and tree volume, but negatively with sapwood proportion.

Evaluation of some wood quality measures of eight-year-old Melia azedarach trees

This study investigated the wood quality of 8-year-old Melia azedarach trees grown in Saudi Arabia. The wood quality of the trees was studied in terms of fibre length, specific gravity, and heartwood/sapwood area. The sampled trees were felled, their stem height and diameter were measured, and discs were cut from the stem base and breast height of each tree. Fibre length and specific gravity at breast height were determined, as well as the area and proportion of heartwood and sapwood at both base- and breast-height cross sections. The results showed that the fibre length of Melia azedarach wood varied between trees and ranged between 0.742 and 0.797 mm. It increased from pith to bark, ranging between 0.62 and 0.92 mm. Specific gravity did not vary among trees, but increased from pith to bark and ranged between 0.366 and 0.432. The proportion of heartwood accounted for about 70% at the base, but decreased to 63.32% at breast height. There was a significant variation in the proportion of sapwood between the base and breast height, as well as between trees. The area of sapwood in the breast-height cross section of Melia azedarach trees was 84.3 cm^2, compared with 102.3 cm^2 at the base; however, the proportion of sapwood was greater at breast height level.

Log Characteristics and Sawn Timber Recovery of Home-Garden Teak from Wet and Dry Localities of Kerala, India

There is a widely held view among smallholders that teak timber produced from small-scale agroforestry systems, especially home-garden forestry, fetches a lower price than that from conventional plantation forestry. To examine the veracity of this view, the wood quality attributes of teak from two home gardens in the district of Ernakulam (wet site) and Palakkad (dry site) in India were compared to those of forest plantation in Nilambur. The logs were graded using standard timber trade practices into high, medium and low quality as determined by the potential sawn timber grade-yield recovery pattern. Of 96 home garden teak logs (aged 35 years) from wet and dry sites, 59% belonged to timber Grade II–IV and the rest were classified as poles. Grade I logs (export quality) with a girth above 150 cm were not available from either of the homesteads. Faster-grown teak in the wet site produced large diameter logs (dbh 1.37 m) with average diameter of 39.6 cm, which is comparable to that of best site quality in India. In contrast, the average dbh for teak grown in the dry site was 24 cm as compared to the average dbh of 31 cm recorded from the same aged forest plantation in Nilambur. It was found that only 10% of logs belonged to Grade II timber and the rest fell under grades III and IV with more frequent visual defects. The sawn timber recovery percentage was lower for the dry site (66.8%), whereas there was no significant difference in grade from the wet and forest plantation sites, with recovery rates of 76.5% and 78.8%, respectively. The general notion that home garden teak has a large proportion of sapwood seems to be baseless, no significant difference being found between the heartwood-sapwood ratio of home-garden and forest plantation teak. Lack of appropriate silvicultural practices in home-garden forestry caused the production of more defective logs, adversely affecting the market price of timber.

Changes in sapwood permeability and anatomy with tree age and height in the broad-leaved evergreen species Eucalyptus regnans

Increases in plant size and structural complexity with increasing age have important implications for water flow through trees. Water supply to the crown is influenced by both the cross-sectional area and the permeability of sapwood. It has been hypothesized that hydraulic conductivity within sapwood increases with age. We investigated changes in sapwood permeability (k) and anatomy with tree age and height in the broad-leaved evergreen species Eucalyptus regnans F. Muell. Sapwood was sampled at breast height from trees ranging from 8 to 240 years old, and at three height positions on the main stem of 8-year-old trees. Variation in k was not significant among sampling height positions in young trees. However, k at breast height increased with tree age. This was related to increases in both vessel frequency and vessel diameter, resulting in a greater proportion of sapwood being occupied by vessel lumina. Sapwood hydraulic conductivity (the product of k and sapwood area) also increased with increasing tree age. However, at the stand level, there was a decrease in forest sapwood hydraulic conductivity with increasing stand age, because of a decrease in the number of trees per hectare. Across all ages, there were significant relationships between k and anatomy, with individual anatomical characteristics explaining 33-62% of the variation in k. There was also strong agreement between measured k and permeability predicted by the Hagen-Poiseuille equation. The results support the hypothesis of an increase in sapwood permeability at breast height with age. Further measurements are required to confirm this result at other height positions in older trees. The significance of tree-level changes in sapwood permeability for stand-level water relations is discussed.