Intermediate Wood Research Articles

Introducing a New Approach in Stand Tending Planning and Thinning Block Designation by Using Mixed Integer Goal Programming

Long-term management plans have been developed for nearly all of the forests in Turkey. These plans are applied at a sub-district management unit level and may contain guidance for both intermediate yield and final yield harvests. To implement an intermediate yield plan, which involves the scheduling of forest thinnings (stand tending), consideration in Turkey is given to the advantages of working in the same terrain and the same general area each year. Therefore, compartments are often clumped together to create thinning blocks, taking into consideration the thinning priority of the stands, road conditions, site index, age, and proximity of the compartments. Further, when preparing annual budgets and planning to meet the market’s needs, forest enterprises require an even flow of intermediate wood volume each year. In this paper, we introduce a new approach in stand tending planning designed to schedule an equal amount of intermediate wood volume each year and to create thinning blocks by minimizing the distance to pre-defined ramps (landings). We developed both linear and nonlinear goal programming models to minimize both the deviations from a harvest volume (annual intermediate yield allowable cut) target and the deviations from a target value determined for the distances (total and average) of the centroid of each compartment to the hypothetical forest ramps. By using the extended version of Lingo 16, we solved the problem with different weights for the deviations in volume and distance that ranged from 0.0 to 1.0, in 10% intervals, which created 11 scenarios. We carefully analyzed the results of each scenario by taking into consideration the wood volume and distance of compartments to the ramps. The best scenario using the linear model produced a deviation in volume scheduled for the entire decade of 6 m3, while the deviation in total distance between harvest areas and ramps was 59.7 km. Scenario 5, with weights of 0.6 for volume and 0.4 for distance, produced these results, where compartments were closest to one another. The best scenario using the nonlinear model also produced a deviation in volume of 0 m3 and the total average deviation in distance between harvest areas and ramps was 8.7 km. Scenario 3, with weights of 0.8 for volume and 0.2 for distance, produced these results. The approach and models described through this study may be appropriate for further integration into forest management planning processes developed for the planning of Mediterranean forests.

Early performance of eight broadleaved species grown as short rotation forest in England

Abstract The overall aim of the experiment was to compare the performance of a range of broadleaved species for their biomass production when grown for short rotations on ex-agricultural sites in England. The objectives were to compare over 7 years on four sites the survival, growth and biomass production of eight promising broadleaved species in relation to one another and two conifer species used as controls. Sites were planted in 2010/2011, and by winter 2016/2017 across all species and sites, the mean height, basal diameter (BD) and diameter at 1.3 m (DBH) were 444, 6.4 and 3.7 cm, respectively, despite considerable weed competition on these ex-agricultural sites. There were statistically significant main effects of species and site on all three measures and also significant interactions between sites and species. Totnes, the site with the highest mean annual temperature and the greatest rainfall, had the most uniform growth of the 10 species. At the three more variable sites, there was a general pattern of red alder (Alnus rubra Bong.) with the greatest growth, followed by a group of Italian alder (Alnus cordata (Loisel.) Duby), hybrid aspen (Populus tremula L. x tremuloides Michx.) and common alder (Alnus glutinosa (L.) Gaertner), then silver birch (Betula pendula Roth) with moderate growth. Sycamore (Acer pseudoplatanus L.), sweet chestnut (Castanea sativa Miller) and ash (Fraxinus excelsior L.), which had been infected with ash dieback, had the poorest growth. The estimated total stem volume after seven growing seasons averaged 31 m3 ha−1, with red alder having the greatest volume production, followed by hybrid aspen and Italian alder. Calculated stem biomass (oven dry tonnes per hectare, odt ha−1) after seven growing seasons averaged over all sites and species was 14.1 odt ha−1 (equivalent to 7 tC). The rapid volume growth and intermediate wood density of red alder and Italian alder combined to give the greatest estimated biomass, averaging 34.5 (17 tC) and 24.0 odt ha−1 (12 tC). At three sites, the estimated biomass of red alder was around 40 odt ha−1. Sitka spruce (Picea sitchensis (Bongard) Carrière) and Japanese larch (Larix kaempferi (Lamb.) Carrière) had a standing biomass estimated at 6.3 and 14.0 odt ha−1, respectively.

Seasonal variations of auxin and gibberellin A4 levels in cambial-region tissues of three conifers (Pinus elliottii, Chamaecyparis obtusa, and Cryptomeria japonica) with inherently different wood densities

We previously reported the species-specific annual ring formation characteristics of three conifers (slash pine (Pinus elliottii), hinoki (Japanese cypress, Chamaecyparis obtusa) and sugi (Japanese cedar, Cryptomeria japonica)) grown in the same stand over 2 years. We found that the species-specific annual ring formation characteristics affected the inherent difference in wood density among these conifers (slash pine > hinoki > sugi). Plant hormones in cambial-region tissues were believed to affect annual ring formation. However, seasonal variation of the amounts of plant hormones in cambial-region tissues had only been examined in a few tree species. In this study, as the first step to elucidating the role of plant hormones in annual ring formation in conifers, we report the seasonal variations of the auxin (indole acetic acid, IAA) and gibberellin A4 (GA4) levels in cambial-region tissues and their effects on annual ring formation in three conifers (slash pine, hinoki, and sugi) with inherently different wood densities.Sugi (small wood density) had significantly higher levels of IAA and formed more tracheids in the early season than in the late season, although slash pine (large wood density) had higher levels of IAA and formed significantly more tracheids in the late season than in the early season. Hinoki (intermediate wood density) had constant IAA levels and formed a constant number of tracheids throughout the season. There were significant positive correlations between the levels of IAA in cambial-region tissues and the number of tracheids formed during late season in the two conifer species. A close relationship was observed between the seasonal ratio of the IAA levels (late/early season) and wood density. No consistent trend in the change in the level of IAA during the transition from earlywood to latewood formation was recognized among the three conifers. The IAA levels in slash pines were significantly higher than those in sugi and hinoki. The GA4 levels had no significant effect on number of tracheids formed in the three conifers. These results suggest that the species-specific seasonal variation patterns of the IAA levels might lead to the inherent differences in wood density among these three conifers through species-specific characteristics in the formation of annual rings.

In Planta Analysis of the Radial Movement of Minerals from Inside to Outside in the Trunks of Standing Japanese Cedar (Cryptomeria japonica D. Don) Trees at the Cellular Level

Although the radial movement of minerals in tree trunks is a widely accepted phenomenon, experimental evidence of their movement in standing trees and underlying mechanisms is very limited. Previously, we clarified that cesium (Cs) artificially injected into the outer part of the sapwood of standing Japanese cedar (Cryptomeria japonica D. Don) trunks moved to the inner part of the sapwood, including the intermediate wood, via active transport by xylem parenchyma cells and diffusion through cell walls and then moved into the heartwood by diffusion. To understand the mechanism underlying the radial movement of minerals in the standing tree trunk, it is necessary to clarify their movement in the opposite direction. Therefore, the present study aimed to determine the radial movement of minerals from inside to outside in the trunks of standing trees at the cellular level. For this, a long hole across the center part of the trunk, which reached the heartwood, intermediate wood, and sapwood, was made in standing Japanese cedar trunks, and a solution of stable isotope Cs was continuously injected into the hole for several days as a tracer. The injected part of the trunk was collected after being freeze-fixed with liquid nitrogen, and the frozen sample was subjected to analysis of Cs distribution at the cellular level using cryo-scanning electron microscopy/energy-dispersive X-ray spectroscopy. The Cs injected into the inner sapwood or intermediate wood rapidly moved toward the outer sapwood via xylem ray parenchyma cells together with diffusion through the cell walls. In contrast, the Cs injected into the heartwood barely moved to the sapwood, although it reached a part of the inner intermediate wood. These results suggest that minerals in xylem ray parenchyma cells in the sapwood are bidirectionally supplied to each other; however, the minerals accumulated in the heartwood may not be supplied to living cells.

An experimental study on change of gas permeability depending on pore structures in three species (hinoki, Douglas fir, and hemlock) of softwood

The purpose of this study is to analyze the pore structure for the heartwood, intermediate wood, and sapwood sections in three species of softwood (hinoki, Douglas fir, and hemlock) and to investigate the correlation of gas permeability depending on pore structure. For this study, gas permeability and pore size were measured by capillary flow porometry, and classification of a novel method was performed to determine the type of pores (through pores, blind pores, and closed pores) based on International Union of Pure and Applied Chemistry (IUPAC). Gas permeability, through pore porosity, and pore size increased from heartwood to sapwood. The results of multiple regression analysis showed that through pore porosity, mean pore size, and bulk density were significant factors affecting gas permeability.

Microcrack propagation in transverse surface from heartwood to sapwood during drying

Microcracks, which are difficult to be observed with naked eyes, occur on the transverse surface during the first stage of wood drying. The precise investigation of their appearance is critical for understanding the mechanism of crack occurrence and propagation, which influence the properties of wood. In this study, the location and time difference of microcrack occurrence on the transverse surfaces of outer heartwood to sapwood via the intermediate wood of Cryptomeria japonica were investigated. Using the developed confocal laser scanning microscope system and a digital microscope, the microcrack propagation was captured dynamically with the wide range of high-quality images; microcracks appeared initially in the heartwood region, immediately after drying. On the other hand, in sapwood, microcrack generation occurred only after microcracks appeared in intermediate wood, and the ones in heartwood started to close or were closed. Finally, most of the microcracks almost closed and some completely disappeared towards the end of the drying process. From this result, it can be established that appropriate drying conditions should be prepared during the early stage of drying to produce high-quality wooden products because microcracks can appear in heartwood, even though the moisture content of the specimen is high.

Pore Characterization in Cross Section of Yellow Poplar (Liriodendron tulipifera) Wood

This study was conducted to analyze the pore structure of Yellow poplar. Cross-sectional surfaces of heartwood and sapwood of Yellow poplar (Liriodendron tulipifera) were observed by SEM, and the true density of the heartwood, intermediate wood and sapwood were measured by gas pycnometery, while gas permeability and pore size of heartwood, intermediate wood and sapwood were measured by capillary flow porometery. The pores were classified as through pore, blind pore and closed pore. It was determined that the permeability was increased due to the content and size of through pore being increased although the total porosity of specimen showed slight difference from pith to bark. The content of through pore porosity was 33.754 % of heartwood and 47.810 % of sapwood, showed an increasing trend from pith to bark, however, those for the blind pore porosity and closed pore porosity were 27.890 % and 19.492 % for heartwood and 19.447 % and 4.660 % for sapwood, showed a decreasing trend from pith to bark. The max pore size of specimens was increased by about 5 times from 5.927 μm to 31.334 μm, and mean flow pore size was increased by about 315 times from 0.397 μm to 12.437 μm from pith to bark.

Cellular level in planta analysis of radial movement of artificially injected caesium in Cryptomeria japonica xylem

Ray parenchyma cells represent the main pathway for mineral radial movement from sapwood towards intermediate wood, based on direct cryo-scanning electron microscopy/energy dispersive X-ray spectroscopy analysis. Ray parenchyma cells are considered to be associated with the radial movement of some elements from sapwood to heartwood in tree trunks. However, this function has not yet been experimentally confirmed. In this study, we analysed the radial movement of caesium (Cs), as a tracer of minerals, through the xylem at the cellular level in standing trees. A solution containing a stable Cs isotope diluted in aqueous acid fuchsin was injected into the outer sapwood of Japanese cedar trees for 3 h, 1, or 4 days. After the injection, the trunk (including the injection points) was freeze-fixed with liquid nitrogen. Subsequently, the trees were felled. The red colour from acid fuchsin was detected in the outer sapwood and did not move passively in the radial direction with free water. For detailed analysis of the Cs distribution in the radial direction (from the red-coloured sapwood towards the pith), we performed cryo-scanning electron microscopy/energy-dispersive X-ray spectroscopy point analysis of the frozen-hydrated samples to analyse the Cs distribution by detecting the characteristic Cs-Lα X-ray peak. In the outer sapwood, Cs was detected in all cell structures at all injection periods. In the inner xylem tissue, Cs was detected in the cell wall and lumen of ray parenchyma cells at 4-day injection, but not at 3-h and 1-day injection. These results suggest that ray parenchyma cells represent the main pathway whereby Cs can move radially from sapwood towards intermediate wood in standing Japanese cedar trees.

Changes in the morphology and functions of vacuoles during the death of ray parenchyma cells in Cryptomeria japonica

Changes in the morphology and functions of vacuoles provide useful information about the mechanism of cell death. In the present study, we monitored the morphology and contents of vacuoles during the death of ray parenchyma cells in the conifer Cryptomeria japonica. In differentiating xylem, ray parenchyma cells had large central vacuoles. In sapwood, vacuoles in ray parenchyma cells contained proteins, an indication that one of the main functions of these vacuoles might be protein storage. A dramatic decrease in the protein content of some vacuoles was detected in the intermediate wood before the initiation of vacuole rupture. Although vacuole rupture was detected from the intermediate wood to the outermost heartwood, some vacuoles were obviously enlarged in the inner intermediate wood. Condensed nuclei were first observed after the rupture of these large vacuoles in ray parenchyma cells. It seems plausible that the autolysis of the contents of ray parenchyma cells might be caused by the rupture of the enlarged vacuoles in the inner intermediate wood.

Sifat Kimia Kayu Eboni pada Perbedaan Pola Strip dan Arah Radial (Chemical Properties of Diospyros celebica Bakh. in Different Streaks Pattern and Radial Direction)

The heartwood of ebony displayed series of axial and alternating black and paler streaks. Accordingly, ebony from Central Sulawesi was classified in two different streaks patterns i.e. SL (spider web) and batang macis (matches stick). We investigated the chemical properties (holocellulose, cellulose, lignin, extractive content, ash and pH value) of sapwood, intermediate, and heartwood from the different streaks patterns of ebony wood. The mean value of holocellulose, cellulose, lignin, ethanol-toluena extractive, hot water extractive, ash contents, and pH value were 76.59±3.02%, 50.62±4.86%, 26.72±3.05%, 9.71± 2.97%, 13.54±1.43%, 0.97±0.32%, 5.56±0.39, respectively. On the basis of t-test, holocellulose, cellulose, and hotwater soluble contents were differed significantly between the two streaks patterns. Analysis of variance showed the radial direction also affected significantly on the chemical contents. The contents of the holocellulose, cellulose, lignin, extractive ethanol-toluen and ash were significantly differed among sapwood, intermediate and heartwood. The heartwood showed higher levels of cellulose, lignin, ethanol-toluena extractive and ash contents than those of other parts. On the contrary, the lowest levels of cellulose, lignin, and ash contents and pH value were found in the intermediate wood region. Keywords : chemical properties, Diospyros celebica, radial direction, spider web, streaks pattern

Classification of Pomegranate Cultivars According to Their Seed Hardness and Wood Perception

AbstractExcessive seed hardness and wood perception will drastically limit consumer's acceptance for pomegranate. To classify pomegranate cultivars, easy‐to‐measure instrumental texture parameters and consumer satisfaction degree were assayed. Twenty pomegranate cultivars (sweet, sour‐sweet and sour tastes) with a wide range of seed hardness were used. The instrumental hardness ranged from 9.60 to 59.5 N/mm, whereas the wood index ranged from 4.77 to 15.3%. Classifications based on hardness and wood perception agreed quite well. Cultivars MA3, ME14, MO5, PTO10 or VA1 were classified as appropriate for fresh consumption whereas cultivars BO1, HZ and WOND were classified as appropriate for industrialization. Cultivars ME12, MEC, MO2 and VA11 were finally recommended for fresh consumption not only due to low seed hardness and intermediate wood perception but also due to sweet taste; however, cultivars BA1 and SM were recommended for industrialization because of its sour taste, which is normally not acceptable to consumers. Finally, the cultivar PTO5 can be used for both purposes, as needed.Practical ApplicationsBecause of market demand, it is important to characterize different pomegranate cultivars, not only to classify them in terms of their beneficial properties but also to gather information about the effects of texture attributes (seed hardness and wood perception) on consumer acceptance. Regressions of (1) seed hardness and wood perception versus descriptive hardness and (2) descriptive hardness and wood perception versus instrumental hardness and wood index allowed the classification of pomegranate cultivars according to their final use (fresh consumption and/or industrialization, mainly juice manufacturing).

Sapwood and intermediate wood thickness variation in Japanese cedar: impacts on sapwood area estimates

Sapwood and intermediate wood thickness variation in Japanese cedar: impacts on sapwood area estimates

The accumulation pattern of ferruginol in the heartwood-forming Cryptomeria japonica xylem as determined by time-of-flight secondary ion mass spectrometry and quantity analysis

Heartwood formation is a unique phenomenon of tree species. Although the accumulation of heartwood substances is a well-known feature of the process, the accumulation mechanism remains unclear. The aim of this study was to determine the accumulation process of ferruginol, a predominant heartwood substance of Cryptomeria japonica, in heartwood-forming xylem. The radial accumulation pattern of ferruginol was examined from sapwood and through the intermediate wood to the heartwood by direct mapping using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The data were compared with quantitative results obtained from a novel method of gas chromatography analysis using laser microdissection sampling and with water distribution obtained from cryo-scanning electron microscopy. Ferruginol initially accumulated in the middle of the intermediate wood, in the earlywood near the annual ring boundary. It accumulated throughout the entire earlywood in the inner intermediate wood, and in both the earlywood and the latewood in the heartwood. The process of ferruginol accumulation continued for more than eight annual rings. Ferruginol concentration peaked at the border between the intermediate wood and heartwood, while the concentration was less in the latewood compared with the earlywood in each annual ring. Ferruginol tended to accumulate around the ray parenchyma cells. In addition, at the border between the intermediate wood and heartwood, the accumulation was higher in areas without water than in areas with water. TOF-SIMS clearly revealed ferruginol distribution at the cellular level. Ferruginol accumulation begins in the middle of intermediate wood, initially in the earlywood near the annual ring boundary, then throughout the entire earlywood, and finally across to the whole annual ring in the heartwood. The heterogeneous timing of ferruginol accumulation could be related to the distribution of ray parenchyma cells and/or water in the heartwood-forming xylem.

Scale-dependent interactions between wood and channel dynamics: Modeling jam formation and sediment storage in gravel-bed streams

[1] A stochastic model is used to investigate how the geomorphic function of wood changes with watershed scale, assuming wood recruitment occurs due to the mortality of individual trees, not to mass recruitment events such as landslides or episodic bank erosion. The model replicates the downstream decline in total wood load observed in the field, but predicts that the functional wood load peaks in channels having bankfull widths about 33% of the characteristic riparian tree height. The model also predicts that the greatest potential impact of jams on channel pattern—both in terms of sediment stored behind individual jams and the potential for jams to trigger avulsions—will typically be associated with channel widths between 25% and 67% of the riparian tree height. The simulation results are used to refine the categories that describe wood in alluvial channels, and the equivalent terms that describe the size of streams with forested riparian areas: small channels (or channels with large wood) are associated with widths less than 25% of the tree height; large channels (or channels with small wood) are associated with widths greater than 67% of tree height; and medium channels (or channels with intermediate wood) have widths between 25% and 67% of the tree height. We surmise that large wood acts primarily to store bed material (in small channels); intermediate wood tends to form channel-spanning jams, which can induce channel avulsions and create anabranched channel patterns (in medium channels); and small wood may increase the morphologic diversity, but does not store significant quantities of bed material or form channel-spanning jams capable of inducing stream avulsions (in large channels).

Seasonal variation of heartwood formation in Larix kaempferi

Heartwood in tree stems provides natural durability and ornamental values to wood products as well as antimicrobial properties to protect living stems from decay. Control of the amount and quality of heartwood is required because of its importance in wood utilization. Despite the importance, the mechanism of heartwood formation has been poorly understood. To obtain further knowledge for understanding this mechanism, we studied the seasonal variation of various components of heartwood formation in Larix kaempferi (Lamb.) Carrière. Dehydration of tracheids at the boundary between sapwood and intermediate wood occurred continuously during the study period. The death of ray parenchyma cells at intermediate wood occurred from spring to summer. The deposition of heartwood substance took place in autumn to winter. Thus, different components of heartwood formation were active in different seasons. Since heartwood formation is a system consisting of several components within a series of continuing processes, understanding the seasonal change of heartwood formation requires monitoring these components simultaneously.

The function of intercellular spaces along the ray parenchyma in sapwood, intermediate wood, and heartwood of Cryptomeria japonica (Cupressaceae)

Intercellular spaces along ray parenchyma (ISRP) are common in many conifer xylems, but their function is uncertain because the in-situ structural network among ISRP, ray parenchyma, and tracheids has not been evaluated. Analysis of water distribution in ISRP from sapwood to heartwood is needed to elucidate the function of ISRP in sapwood, intermediate wood, and heartwood. We used cryo-scanning electron microscopy, x-ray photography, and water content measurement in xylem to analyze the presence of liquids in ISRP, ray parenchyma, and tracheids from sapwood to heartwood in Cryptomeria japonica (Cupressaceae). In sapwood, almost all ISRP were empty. "Cingulate-cavitated regions", which lose water along the tangential direction within one annual ring, formed in the earlywood tracheids, and their frequency increased toward the inner annual rings, whereas ray parenchyma cells were alive and not involved in the partial cavitation. In intermediate wood, almost all ISRP and earlywood tracheids and many of the ray cells were empty, and only some latewood tracheids retained liquid in their lumina. The ISRP were connected with tracheids via gas-filled ray parenchyma cells. The ISRP work as a pathway of gas for aspiration of ray parenchyma cells in sapwood. On the other hand, the occurrence of a gas network between ISRP, ray parenchyma, and tracheids facilitates cavitation of tracheids, resulting in the generation of low-moisture, intermediate wood.

In vitro hydroxylation of a norlignan: From agatharesinol to sequirin C and metasequirin C with a microsomal preparation from Cryptomeria japonica

Abstract In vitro hydroxylation of the norlignan agatharesinol to sequirin C and metasequirin C was demonstrated for the first time. After incubating agatharesinol with a microsomal preparation from the heartwood side of the intermediate wood of Cryptomeria japonica in the presence of cofactors, the aromatic ring-monohydroxylated derivatives of agatharesinol, sequirin C and metasequirin C, were formed. Although hydroxylation hardly occurred in the absence of cofactors, it could be initiated by adding NADPH or NADH, and was enhanced by further adding FAD or FMN. When microsomal preparations from the sapwood or from the sapwood side of the intermediate wood were used, hydroxylation did not occur. This in vitro conversion of the norlignans indicates that the hydroxylation of agatharesinol to sequirin C and metasequirin C is part of the in vivo biosynthetic pathway of norlignans. Another C. japonica norlignan, sugiresinol, which is a side chain-cyclized isomer of agatharesinol, does not seem to be accepted as a substrate, because hardly any hydroxysugireinol was formed after similar incubation with the enzyme.

Cellular level observation of water loss and the refilling of tracheids in the xylem of Cryptomeria japonica during heartwood formation

The mechanism of heartwood formation in Cryptomeria japonica D. Don has long been studied since heartwood formation is a fundamental physiological feature of trees. In this study, the water distribution in the xylem of C. japonica was investigated at the cellular level to reveal the role of water distribution in the xylem during heartwood formation. Samples were taken from different heights of each trunk, in which the phases of heartwood formation differed. These were designated as SIH, which consisted of sapwood, intermediate wood, and heartwood; SI, which consisted of sapwood and intermediate wood but no heartwood; and S-all, which consisted entirely of sapwood. Cryo-scanning electron microscopic observations of the heartwood-formed (SIH) and non-heartwood-formed (SI and S-all) xylem revealed different patterns of water distribution changes in tracheids between the latewood and earlywood. In the latewood, almost all tracheids were filled with water in all areas from the sapwood to the heartwood (98–100% of tracheids had water in their lumina). In the earlywood, however, the water distribution differed between the sapwood (95–99%), intermediate wood (7–12%), and heartwood (4–100%). Many of the tracheids in the xylem, where the sapwood changed to intermediate wood lost water. In the heartwood, some tracheids remained empty, while others were refilled with water. These results suggest that the water distribution changes in individual tracheids are closely related to heartwood formation. Water loss from tracheids may be an important factor inducing heartwood formation in the xylem of C. japonica.

Radial distribution patterns of the green moisture content in trunks of 46-year-old red cypress (Chamaecyparis formosensis)

Understanding the green moisture content and wood density is important for effective forest management. Radial distribution patterns in the green moisture content (MC) and basic density (BD) in stems of red cypress (Chamaecyparis formosensis) were investigated in 69 plantation trees that were 46 years old. An increment core was collected from each sample tree at breast height (1.3 m). Five radial positions were defined: pith piece (Pith), inner heartwood (IHW), outer heartwood (OHW), intermediate wood (TSH), and sapwood (SW). Results showed that the average MC was highly dependent on the individual tree. Average values of the MC obtained from the TSH were significantly lower than those for the other positions. The MC of heartwood was higher than that of SW. Distribution patterns of the MC in the radial direction varied among trees. Radial variations in MC and BD were greater than in between-tree variations. Six types of radial distribution patterns of MC were detected for sample trees. MC values increased with decreasing BD (except for the TSH). Positive correlations were found between adjacent sampling positions in both MC and BD.

Within-Stem Water Distribution in Living Trees Of Some Conifers

Water distributions within living stems of 11 species from three conifer families were observed with soft X-ray photography. The moisture contents at breast height of the trees were also measured. In all but one case, sapwood was almost saturated with free water. Intermediate wood, which was a narrow white band located between the sapwood and heartwood, was generally common in species with coloured heartwood. In heartwood, water distribution varied not only among species, but also within species, and even within a stem. In seven of the 11 species investigated, well-developed wetwood (the phenomenon of free water accumulated in heartwood) was observed. The frequent presence of wetwood led to the conclusion that it was a common feature in some groups of conifers. It is suggested that the view that wetwood is an abnormal feature may be incorrect because so far wetwood surveys have only focused on a few species that are important for forestry, e.g., hard pines. An extensive survey of many specimens belonging to various species is required to understand the mechanism of wetwood development.