Outer Wood Research Articles

Suitability of Chrysophyllum albidum from moist semi-deciduous forest in Ghana as a raw material for manufacturing paper-based products

ABSTRACTThe global demand for paper-based products continues to increase amidst challenges with raw material supply to the pulp industries. Considerable efforts to discover new wood resources from tropical forests to widen the material stock are ongoing. This study examined the suitability of the outer and inner wood fibres from different axial sections (i.e., butt, middle and top) of Chrysophyllum albidum from a moist semi-deciduous forest in Ghana for paper production. The fibre morphology and derived indices [i.e., Runkel Ratio, Slenderness Ratio, Flexibility Coefficient, Coefficient of Rigidity, Luce’s Shape Factor and Solids Factor] were determined using the methods by the International Association of Wood Anatomist. C. albidum inner and outer wood fibres were generally long and thin with wide lumen. The fibre-derived indices were similar to those of many popular paper-producing timbers such as Acacia mangium and Pinus sylvestris. The fibre morphology and derived indices of C. albidum meet the recommended thresholds for fibres for manufacturing writing and printing papers with good tearing and bursting strength properties. Thus, the wood’s fibres would be suitable for producing papers with good strength properties. Its utilization will contribute to expanding the raw material sources for the pulp and paper industry.

Kualitas Pemesinan Kayu Punak (Tetramerista glabra Miq.) Menurut Kedalaman Batang

This paper presents the results of the quality of wood machining according to the depth of the stem. Testing of machining properties refers to modified ASTM D-1666-64. The results showed that the quality of wood machineries of the outside of the steam was fair to good and the inside of the steam was good to excellent. The fuzzy grain was most found. The quality of wood inside the stem is generally better than the outer wood. The depth of the stem has a significant effect on the value of defect free turning. Punak wood can be recommended to be processed into a variety of wood working products such as moulding, wood carvings, pegs, fence, the other items of turnings, panels, door components, tables, and wallcoverings.

Determining the predictive accuracy of whole tree modulus of elasticity (MOE) of 14-year-old loblolly pine using density and dynamic MOEs estimated by three different acoustic tools

Resonance based acoustic tools for evaluating wood properties have been reported to be more accurate in estimating the expected log MOE than time-of-flight (ToF) ones. However, there is no published study on the variations within different brands on these two major classes of acoustic tools. In this study, models were developed to predict the whole tree static MOE (WMOET) and rupture (WMORT) using log dynamic MOEs estimated by two resonance tools [Director HM200 (EHM200) and FAKOPP resonance log grader (ERLG)], ToF [FAKOPP Microsecond Timer (EFMT)], and density (green density, air-dry density) for a 14-year-old loblolly pine stand from two sites in the southern USA. The log velocity estimated by ToF was 33 and 30% more as compared to the resonance-based tools (Director HM200 and FAKOPP RLG respectively); translating into whole log static MOE (WMOEL) been 11 and 20% lower than those estimated by the resonance (HM200 and RLG respectively), and 90% lower than that estimated by the ToF tools (EFMT). Although the dynamic MOE estimated by ToF tool (EFMT) was higher, its WMOET predictive performance (R2 = 51%) lies between the 39 and 74% for the resonance based tools (HM200 and RGL respectively). This result supports the theory that ToF tools generate dilatational wave, and hence their velocity will be generally higher than resonance tools. The presence of predictive variation within the resonance suggests the need for within tools calibration. The linear relationship between the WMOET vs Etree was stronger than that of WMOET vs EHM200 suggesting that the ToF acoustic tool measurements are not restricted to the outer wood zone for small diameter logs.

A critical analysis of methods for rapid and nondestructive determination of wood density in standing trees

Field methods for rapid determination of wood density in trees have evolved from increment borer, torsiometer, Pilodyn, and nail withdrawal into sophisticated electronic tools of resistance drilling measurement. A partial resistance drilling approach coupled with knowledge of internal tree density distribution may offer an alternative solution for wood density surveys in the future. Finding ways to nondestructively assess wood density in trees has been a quest by foresters and wood scientists around the world. In the past several decades, traditional increment borer methods have gradually evolved into sophisticated electronic tools of resistance drilling measurements. We provide a comprehensive review of research development in the use of several field nondestructive methods for rapid determination of wood density in trees and discuss pros and cons of each method for field applications. The use of the increment borer has been a standard method for assessing wood density in trees, and it has been further developed into a system approach allowing the use of outer wood cores and knowledge of internal density distribution for predicting wood density of major tree components. Studies on the use of torsiometer, Pilodyn, and nail withdrawal tools have had very limited success and do not warrant replacement of the increment borer. Resistance drilling, on the other hand, has emerged as a potential tool for more efficient and economical collection of wood density information in trees. The resistance drilling method has considerable advantages over other methods in terms of less damage to trees, faster operation, and higher measurement sensitivity. Internal friction is a key factor that currently hinders further application.

The (w)hole story: Facilitation of dead wood fauna by bark beetles?

Facilitation between species is thought to be a key mechanism in community assembly and diversity, as certain species create microhabitats for others. A profound characteristic of forest ecosystems is a large amount of dead wood which is colonised by a vast array of invertebrate species. Bark beetles (Scolytinae) feed and breed on dying or dead trees, puncturing holes into the bark and engraving inner bark and outer wood with their galleries. These holes and galleries might facilitate other invertebrates by providing access to the inner bark for shelter, feeding and reproduction. We tested this hypothesised facilitative interaction during the early decomposition phase of coarse woody debris of spruce (Picea abies L. Karst.) incubated in two environmentally contrasting forest sites in the ‘common garden’ experiment LOGLIFE. We sampled invertebrates in 25 cm diameter logs at different degrees of colonisation by bark beetles. Our results indicated that (1) bark beetles facilitated the entrance into spruce logs of other invertebrates with body width that matched the size of bark-beetle holes, and (2) the abundance of invertebrates was often positively related to the proportional surface area of inner bark consumed by bark beetles, but more so in the nutrient-rich site than in the nutrient poor site. This study provides the first quantitative test of facilitation between invertebrate clades in dead wood communities. Including facilitative interaction in community assembly studies may change some predictions about relationships between tree functional traits and invertebrate diversity and will lead to a more accurate and comprehensive understanding of dead wood communities.

Wood Specific Gravity Variations and Biomass of Central African Tree Species: The Simple Choice of the Outer Wood.

ContextWood specific gravity is a key element in tropical forest ecology. It integrates many aspects of tree mechanical properties and functioning and is an important predictor of tree biomass. Wood specific gravity varies widely among and within species and also within individual trees. Notably, contrasted patterns of radial variation of wood specific gravity have been demonstrated and related to regeneration guilds (light demanding vs. shade-bearing). However, although being repeatedly invoked as a potential source of error when estimating the biomass of trees, both intraspecific and radial variations remain little studied. In this study we characterized detailed pith-to-bark wood specific gravity profiles among contrasted species prominently contributing to the biomass of the forest, i.e., the dominant species, and we quantified the consequences of such variations on the biomass.MethodsRadial profiles of wood density at 8% moisture content were compiled for 14 dominant species in the Democratic Republic of Congo, adapting a unique 3D X-ray scanning technique at very high spatial resolution on core samples. Mean wood density estimates were validated by water displacement measurements. Wood density profiles were converted to wood specific gravity and linear mixed models were used to decompose the radial variance. Potential errors in biomass estimation were assessed by comparing the biomass estimated from the wood specific gravity measured from pith-to-bark profiles, from global repositories, and from partial information (outer wood or inner wood).ResultsWood specific gravity profiles from pith-to-bark presented positive, neutral and negative trends. Positive trends mainly characterized light-demanding species, increasing up to 1.8 g.cm-3 per meter for Piptadeniastrum africanum, and negative trends characterized shade-bearing species, decreasing up to 1 g.cm-3 per meter for Strombosia pustulata. The linear mixed model showed the greater part of wood specific gravity variance was explained by species only (45%) followed by a redundant part between species and regeneration guilds (36%). Despite substantial variation in wood specific gravity profiles among species and regeneration guilds, we found that values from the outer wood were strongly correlated to values from the whole profile, without any significant bias. In addition, we found that wood specific gravity from the DRYAD global repository may strongly differ depending on the species (up to 40% for Dialium pachyphyllum).Main ConclusionTherefore, when estimating forest biomass in specific sites, we recommend the systematic collection of outer wood samples on dominant species. This should prevent the main errors in biomass estimations resulting from wood specific gravity and allow for the collection of new information to explore the intraspecific variation of mechanical properties of trees.

Growth characteristics and wood properties of 26-year-old Eucalyptus alba planted in Indonesia

Growth characteristics and wood properties were investigated for 26-year-old Eucalyptus alba trees grown in Ambon, Indonesia. The mean stem diameter and tree height were 27·9 cm and 19·5 m, respectively. In addition, the mean stress-wave velocity (SWV) of trees and basic density (BD) of outer wood (2 cm from the bark) were 3·23 km s− 1 and 0·67 g cm− 3, respectively. The mean BD of outer wood was almost the same in fast-growing and medium-growing trees. No significant correlations were found between stem diameter and SWV of trees and BD of outer wood. Based on the results, trees with faster-growing characteristics of E. alba do not always have the lower wood properties. Radial profiles in relation to relative distance from pith to bark were almost the same among three growth categories, suggesting that xylem maturation in E. alba might depend on cambial age.

Calendar-dated glacier variations in the western European Alps during the Neoglacial: the Mer de Glace record, Mont Blanc massif

Holocene glacier records from the western European Alps are still sparse, although a number of sites are well suited to constraining pre- and early- Little Ice Age (LIA) glacier advances. The present study provides the first dendrochronologically-based and calendar-dated Neoglacial glacier chronology for the Mont Blanc massif, French Alps. It is based on the analysis of over 240 glacially buried Pinus cembra subfossil logs and wood remains found either embedded-in-till or as detrital material in the Mer de Glace right lateral moraine. Only a few of the samples were found to be ‘formally in situ’ but we show that some logs were ‘virtually in situ’ (not rooted but showing little or no evidence of reworking) and could be used to accurately reconstruct past glacier margin behavior in space and time. Uncertainties regarding the other samples may relate to original growth location and/or to outer wood decay. The resulting dates (followed by a ‘+’) were therefore considered maximum-limiting ages for glacier advances. The main burial events – interpreted as glacier advances – occurred between ca 1655+ and 1544+ BC, between ca 1230+ and 1105+ BC, between ca 1013+ and 962+/937+ BC, at ca 802–777 BC, after 608+ BC, between 312 and 337AD, between ca 485+ AD and 606+ AD, between 1120 and 1178AD, between ca 1248 and 1278+/1296AD, and after 1352+ AD. These advances predate the late LIA maxima known from historical sources. The magnitude of the advances gradually increased to culminate in three near-Neoglacial maxima during the 7th, 12th and 13th centuries AD, followed by a first LIA/Neoglacial maximum in the second half of the 14th century AD. The pattern of Neoglacial events described here is coherent with Central and Eastern Alpine glacier chronologies. This indicates marked synchronicity of late Holocene glacier variability and forcing at a regional scale, although occasional differences could be detected between ‘Western’ and ‘Eastern’ records. The Mer de Glace record also confirms the link between the timing of sediment erosion in a high-elevation glaciated Alpine catchment and subsequent deposition in the sub-alpine Lake Bourget.

Collapse of Eucalyptus nitens Wood After Drying Depending on the Radial Location Within the Stem

Collapse is almost certain to occur in the industrial drying of Eucalyptus nitens and, as such this prevents the lumber manufacturing industry in Chile from producing commercial solid wood products from this species. This problem is still unsolved, and different studies to reduce collapse are currently underway. In this exploratory study, shrinkage and collapse after drying of Eucalyptus nitens was measured for boards cut from different radial locations within the stem (core, transition, and outer wood from pith to bark) and having different annual ring orientations (flat-sawn and quarter-sawn). Though exploratory, the results appear to confirm that pieces that were cut from the center of the trees were less susceptible to collapse than pieces cut from the transition zone between the center and the periphery. On average, collapse in transition wood was approximately 50% higher than the collapse observed in wood cut from the central zone of the trees.

Radial changes in wood specific gravity of tropical trees: inter‐ and intraspecific variation during secondary succession

SummaryVariation in wood specific gravity (WSG) within and across species of tropical trees is poorly studied in relation to vegetation change during tropical forest succession. We investigated WSG of 91 species in eight long‐term plots along a successional chronosequence in north‐eastern Costa Rica.Radial changes in WSG were described by the rate of change (slope) along the stem radius. Significant radial changes were found in 42 of 74 species, with 37 species exhibiting increases from inner to outer wood, and five exhibiting decreases. Radial increases were commonly observed in species with inner WSG below 0·5, whereas radial decreases were observed in species with inner WSG above 0·7.Wood specific gravity weighted by cross‐sectional area (wWSG) varied four‐fold among species. Species classified as second‐growth specialists had lower wWSG, lower inner and outer WSG, and higher slopes than old‐growth specialists; successional generalists showed intermediate trait values.Among 18 species sampled in both second‐ and old‐growth forests, four species (22%) showed significant variation in wWSG between forest types. Of 33 widely sampled species, seven species (21%) showed a significant effect of stem diameter on wWSG.Second‐growth plots had lower stand‐level wWSG and more pronounced radial increases than old‐growth plots. Individual tree biomass for species with radial increases and low WSG was substantially underestimated when based on unweighted WSG compared with wWSG.Wood specific gravity varied with successional stage at multiple levels: within species, among successional specialist groups, and across plots of varying ages. Radial increases in WSG are common among trees in early and intermediate stages of tropical forest succession. This trait may confer growth advantages early in succession and increased resistance to physical or biotic damage during later successional stages.

First report of gummosis caused by Botryosphaeria dothidea on mango trees in Guangxi, South China.

Mango (Mangifera indica) is an economically important fruit crop in southern China, and gummosis is one of the most important of its diseases. Under severe conditions, the outer wood of branches cracks, and exudes a yellow to brown gum, and the whole plant declines. In June, 2012, symptomatic mango branches were collected in Guangxi province. On potato dextrose agar, isolates of similar morphological characteristics were consistently recovered, with 80% isolation rate from 45 surface-sterilized branch pieces. Conidia were hyaline, aseptate, and fusiform, and measured 18-28×4-6 μm. The fungus was identified as Botryosphaeria dothidea based on morphological characteristics (Lazzizera et al., 2008). The rDNA internal transcribed spacer region (ITS), the β-tubulin gene, and the translation elongation factor 1-α gene of one isolate (L15,) showed 99-100% identity to B. dothidea, (Gen- Bank accession Nos. GQ421485, JF441083 and HQ660485). Pathogenicity of three isolates was tested on three green twigs and three 3-year-old branches in mango orchards in Nanning (Guangxi). Three wounds were made for each location with a sterilized needle. Mycelial plugs were placed on the wounds and wrapped with parafilm. Two weeks later, typical brown lesions were observed on the branches, and gum exuded from infected tissues, but no symptoms were seen on controls inoculated with sterile agar plugs. Koch’s postulates were fulfilled by reisolation of B. dothidea from diseased branches. In China, the main causal agent of mango gummosis has been identified as Lasiodiplodia theobromae (Li et al., 2013). However, to our knowledge, this is the first report of B. dothidea causing mango gummosis in the country.

Spatial variations in non-structural carbohydrates in stems of twelve temperate tree species

The radial, axial and inter-specific variations in concentrations and contents of non-structural carbohydrates (NSC) in stems were investigated for 12 Chinese temperate tree species. These species had contrasting leaf phenology (evergreen and deciduous) and wood types (non-, ring- and diffuse-porous wood). For each species, we sampled bark (periderm and phloem), outer wood (light-colored) and inner wood (dark-colored) at four heights along the stem (stump, breast height, crown base and mid-crown). Concentrations of total NSC (TNC, sum of sugars and starch), sugars and starch were much higher in bark than those in wood. On average, contents of sugars and starch accounted for 48 and 52 % of the TNC, respectively, and contents of TNC in bark, outer wood, and inner wood accounted for 34, 38, and 28 % of the stem total, respectively. Bark was the major pool of sugars in the stem (accounting for 50 % of the stem total on average), while outer wood was the major pool of starch (41 %). The concentration of sugars varied axially for all the conifers but did not for the broadleaved species. Mean concentrations of TNC, sugars and starch in stem varied by more than twofold among the species. However, there were no significant differences in these values for the species groups with different leaf phenology or wood types. Ignoring the radial, axial and inter-specific variations in NSC in stem would introduce large bias in estimating NSC storage at tree or ecosystem levels.

TREATABILITY OF PLANTATION TIMBER SPECIES WITH CCA (COPPER·CHROME·ARSENATE) PRESERVATIVES AND THEIR EFFECTIVENESS AGAINST INSECT AND FUNGAL ArrACK

This study was conducted to asscss the treatability of four plantation timber species (PiIlIlScariboca, 1/('\'('(/ brasiliensis, EII(,I1/I,/)IIIS gran.lis and EII('(/{y{)IIIS microcorvs) withCoppcr-Chromc-Arscn.uc (CC A) by using pressure impregnation full-cell process. Thetreatability of core wood and outer wood of the species were also investigated. Treatabilitywas evaluated by measuring the preservative retention (Net Dry Salt Rctcnt ion or NDSR)and dcpt h of pellet rat ion.According to the results. Pinus I'IIl'ih(/(,1I showed the highest treatability while treatabilityof //C'I'I'(/ hrasilicnsis, Em (/{YfiIIlS grandis and EII('(/II'f'IIIS microcorvs were respectivelylower. A significant negative corrckuion was observed between density of the timber andtill' treatability. Rased on depth of penetration of preservatives. Pinus (,(/I'i/)II(,(/ and 1/('\'('(/brasiliensis were classified as permeable to preservative treatment. E. grandis was resistantwhile E. microtorvs was extremely resistant to preservative treatment.Trc.unbilitv of outer wood of all the species were higher than that of core wood indicatingthe higher pcnncabiiity of outer S;IPWOOt! area compared with the inner core wood.Trc;lting schedule with initial vacuum of -O.X bar. pressure of 6.5 bar maintained for IXOminutes ami final vacuum of -(),X bar was effective treatment of l l evcu hrasilicnsis. Evenwith this pressure. it was unable to achieve depth of penetration levels as specified in theSri Lankan Standards for E. grandis and E, IIIicro 1'01'\'.1'.When wood samples were exposed to exterior ground contact in the grave yard test for fivemonths. none of the treated samples were infected, hut untreated control samples wereattacked hv fungi and termites. This indicates the effectiveness of the CCA treatment incontrolling fungal and insect attack.

Wood decay caused by Heterobasidion parviporum in juvenile wood specimens from normal- and narrow-crowned Norway spruce

Heterobasidion parviporum (Fr.) Niemelä & Korhonen is a serious forest pathogen affecting the quality of Norway spruce (Picea abies (L.) Karst), especially in northern hemisphere. Here, we studied the wood decay caused by this pathogen in small wood specimens of 19-year-old normal (P. abies) and narrow crowned (P. abies f. pendula) Norway spruce trees. After six months of incubation, wood specimens taken next to pith (inner) and bark (outer) at 1 m height from the stem base were measured to obtain the percent dry weight loss. The fungal development was also analyzed using Scanning Electron Microscopy (SEM). We found that the crown type (or genetic entry) had no effects on the weight loss. However, outer wood specimens lost, on average, more weight than inner ones. Similarly, wood density and content of lignans were lower at outer sections, opposite to the free glucose content. Wood density correlated negatively with the weight loss of wood specimens, regardless of crown type. Considering that narrow- and normal-crowned trees responded similarly to H. parviporum wood decay, our findings support the potential use of narrow-crowned Norway spruce in practical forestry since they can produce higher stem yield at very dense plantation and without thinning requirements.

Wood density variation in four plantation species growing in Bangladesh

Wood density is a unique integrator of strength properties and life-history traits of trees, and has importance in carbon estimation. It varies vertically and radially within individual tree in tropical species. The aim of this study was to determine whether wood density variations were dependent on tree diameter or age by comparing trees of same age but with different diameters for four important plantation species, such as Chukrasia tabularis A. Juss., Dipterocarpus turbinatus Gaertn., Michelia champaca L. and Syzygium grande (Wright) Walp. in Bangladesh. Twenty trees were selected for coring in each species and wood density was measured at 1 cm interval from pith to bark. Steeper regression slopes in small diameter trees and absence of significant relationship between outer wood density and tree diameter imply age-dependent wood density variation in C. tabularis and M. champaca. Conversely, the diameter-dependent wood density was found in S. grande. Steeper regression slopes in small diameter trees and slightly higher outer wood density in large diameter trees suggesting mixed response of both age and diameter in D. turbinatus. Therefore, wood density variation in plantations species is influenced not only by tree age but also diameter, or both which has implications in plantation management and biomass estimation in the tropics.

An evaluation of wood properties of <i>Pinus caribeae</i> (Morelet) in Oluwa Forest Reserve, Ondo State, Nigeria

This paper examines the effects of within tree variation on wood density, ring width and anisotropic shrinkage of Pinus caribeae (Morelet) among tree partitions in Oluwa pine plantation. Five 15-year old Pinus caribeae (Morelet) in three partitions were randomly selected from the plantation and felled for the study. Wood samples were prepared from five height levels, 10%, 30%, 50%, 70% and 90% and also among the wood type; inner wood, middle wood and outer wood positions of the stem according to standard procedures. The result showed the wood is dense, dimensionally stable with an average density of 0.55g/cm3. Among three partitions, ring width variation had a marked effect on wood density and anisotropic shrinkage of the wood (p < 0.05). A strong positive correlation was established between density and shrinkage properties. The relationship between ring width and anisotropic shrinkage was positive. Thus, it may be possible to use wood density and grain orientation biometry to predict anisotropic shrinkage of the wood and its dimensional stability.Key words: Density, Ring width, anisotropic shrinkage, Pinus caribeae (Morelet)

Physical and Mechanical Properties of Loblolly and Slash Pine Wood from Uruguayan Plantations

Abstract The available wood supply in Uruguay comprises trees that grow so fast in intensively managed plantations that they reach saw timber size in 25 years or fewer. Trees harvested at this age contain high proportions of juvenile wood that may lead to lumber low in stiffness and strength. A project was conducted to characterize fast-growing wood, determine engineering properties, and assign visual structural grades of lumber. The present study evaluated properties of 15- and 25-year-old loblolly (Pinus taeda L.) and slash (Pinus elliottii Eng.) pine to better understand the current available locally produced wood material. A total of 175 stump bolts from trees from two commercial plantations provided inner and outer small clear specimens for property evaluation. Specific gravity, bending, compression parallel to grain and perpendicular to grain, and shear tests were conducted. Most properties significantly increased radially away from the pith. The outer wood appears to be denser, stiffer, and stronger than the inner wood in both plantations. Wood from 15-year-old San José trees showed significantly lower properties than 25-year-old Paysandú trees, and had considerably inferior properties compared with values listed in the Wood Handbook (US Department of Agriculture 1999). Our results on 25-year-old Paysandú small clear specimens showed properties similar to those of previous studies on small clear and structural size pieces. Therefore, it can be expected that lumber from 25-year-old Paysandú trees will eventually comply with required properties for structural use. A second on-going phase of this study addressing structural size specimens will help to establish more definite conclusions.

Radial variation in Kraft pulp yield and cellulose content in Eucalyptus globulus wood across three contrasting sites predicted by near infrared spectroscopy

There is little published information on the variability of pulp yield within eucalypt stems. This is primarily due to the difficulty in measuring pulp yield in small samples, especially those obtained nondestructively. Thus, information of the effect of site, climate, and silviculture on pulp yield variability is lacking, minimizing its consideration in the economic optimization of pulpwood production. Near infrared spectroscopic measurement of pulp yield directly from intact wood surfaces at a small, radial sampling interval provides forest managers with opportunities to better understand and manage its sources of variability. Calibrations based on solid wood samples were constructed to describe radial variation in Kraft pulp yield and cellulose content using intact wood samples from Eucalyptus globulus Labill. Plantations at three sites with contrasting annual rainfall were studied. Pulp yield and cellulose content were higher at the more productive, wetter sites. Outer wood near the cambium had pulp yield values up to 8% higher than those at the pith. There was no clear intra-annual cycle of variation. The more productive sites exhibited significantly steeper pith-to-bark increases in pulp yield than the driest site. This has implications for optimizing pulp productivity by considering rotation length and site quality.

Within-ring movement of free water in dehydrating Norway spruce sapwood visualized by neutron radiography

Abstract This study is a first approach to visualize moisture distribution and movement between annual rings during sapwood drying by neutron imaging (NI). While Norway spruce [Picea abies (L.) Karst.] sapwood beams were allowed to dehydrate on a balance at ambient conditions, NI was performed in 1–10 min time steps. From NI raw files, radial dimensional changes were calculated during dehydration and transmission profiles were drawn for different relative moisture content (MC) steps from full saturation until equilibrium moisture content. The NI technique proved to be a useful tool to visualize the movement of free water within, and between, annual rings. Removal of free water in the middle part of the wood beam did not proceed continuously from the surface to the central part, but was strongly influenced by wood anatomy. Water is removed from earlywood during early stages of dehydration and later, at higher moisture loss (<50% MC), from the main latewood parts. It is therefore concluded that the radial dimensional changes measured at moderate moisture loss are not only caused by cell wall shrinkage of the outer wood parts located beneath the wood surface, but a result of elastic deformation of earlywood tracheids under the influence of negative hydrostatic pressures.

Radial Variation in Microfibril Angle and Compression Properties of Paraserianthes Falcataria Planted in Indonesia

Paraserianthes falcataria (L.) Nielsen is an important plantation species in Indonesia. The objective of this study was to understand the radial variation of microfibril angle in the S2 layer of the wood fiber wall (MFA) in P. falcataria, and its relationship to compression properties parallel to the grain, including modulus of elasticity (E) and compression strength (σ). MFA gradually decreased from pith to bark while both E and σ increased from pith to bark. Significant differences in MFA, E, and σ were found among the five sample trees. Single-regression analysis of wood and compression properties revealed that the compression properties of core wood were affected mainly by density, whereas those in outer wood were affected by both MFA and air-dry density (AD).