Early establishment of broadleaved trees after logging of <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> and <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> plantations with different understory treatments

We studied the effects of the amount of advanced regeneration before logging and different understory treatments on forest recovery, particularly the establishment of lucidophyllous (evergreen broadleaved) species, following the logging of conifer plantation with a focus on the sprouting ability. The establishment of lucidophyllous tree and shrub species originating from advanced regeneration was closely related to the total amount of these elements in the advanced regeneration, regardless of understory treatment. The understory-left treatment could preserve understory as surviving individuals by high proportion (60% or more of the understory) compared with the understory-cleared practice after logging. However, half of the surviving individuals were damaged to some extent by logging and skidding. Relatively large trees were likely to survive with no damage, indicating that they face a lower risk than smaller trees. In understory-cleared stands, a high proportion (60% or more) of the understory regenerated by resprouting. However, the resprouting ratio depended on tree size and species. Therefore, as well as the amount of the understory, the tree size of understory before logging would be also an important factor for early forest recovery. Further, the infrequent (low-density) species could easily disappear after logging because of their low resprouting ratio and low density. Thus, recovery from resprouting alone would risk simplification of the species composition after logging. We concluded that leaving the developed understory intact before logging can enhance the speed and biodiversity of forest recovery.     

Estimation of stand attributes in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> and <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> stands using QuickBird panchromatic data

This study aims to estimate stand density and stand volume in Cryptomeria japonica and Chamaecyparis obtusa stands from high-resolution satellite data and verify the reliability and uncertainty of the data. Sixty circular sample plots of 0.04 ha each were established. Their stand densities were estimated from the number of tree crowns derived from high-resolution satellite data using the watershed method. Stand densities derived from field surveys in the sample plots were compared with those obtained from high-resolution satellite data by stand age class. As a result, there was a positive correlation between them for sample plots of 41 years of age and over (R = 0.82); however, there was no correlation between them for sample plots of 40 years and under. Individual diameters at breast height (DBH) were estimated from crown areas obtained from high-resolution satellite data for the two species. Using the estimated DBH, individual tree heights were predicted from the height–diameter curves. Stand volumes were estimated from the sum of individual volumes, which were derived from volume formulas having two variables, i.e., DBH and height. Stand volumes derived from the field survey were compared with those obtained from high-resolution satellite data. The correlation coefficient between them for stands of 41 years of age and over was 0.78.     

Structural unit of xylans from sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) and hinoki (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>)

Arabinoglucuronoxylans (AGXs) isolated from the holocellulose of sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) contained one 4-O-methyl-d-glucopyranosyluronic acid (4-O-Me-d-GlcAp) residue per 6.2 d-xylopyranose (d-Xylp) residues and one 4-O-Me-d-GlcAp residue per 3.8 d-Xylp residues. These AGXs were subjected to partial acid hydrolysis. Analyses by size exclusion chromatography and electrospray-ionization mass spectroscopy of the neutral sugar fractions in the hydrolysates showed the presence of xylooligosaccharides having a degree of polymerization of 2-8 in addition to d-Xyl, suggesting that the AGXs from sugi and hinoki contained unsubstituted chains consisting of at least eight d-Xyl residues. The acidic sugars in the hydrolysates were separated into two series of aldouronic acids composed of 4-O-Me-d-GlcAp and d-Xylp by ion-exchange chromatography. The first series included aldouronic acids from aldobiouronic acid (4-O-Me-d-GlcAp-Xyl) to aldopentaouronic acids (4-O-Me-d-GlcAp-Xyl₄). The second series were aldouronic acids composed of two 4-O-Me-d-GlcAp residues and 2-4 d-Xyl residues. In these acidic sugars, the uronic acid side chains were located on two contiguous d-Xyl residues. These facts indicated that AGXs from sugi and hinoki had a structural unit containing two 4-O-Me-d-GlcAp residues on two contiguous d-Xyl residues as well as AGXs from spruce and larch.     

Fine root biomass and morphology of <Emphasis Type="Italic">Pinus densiflora</Emphasis> under competitive stress by <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>

The fine root (diameter ≤2.0 mm) biomass and morphology of Japanese red pines (Pinus densiflora) grown under different aboveground conditions (i.e., high and low competitive environments) were examined in a pine–cypress mixed forest. All P. densiflora subject trees were about 40 years old, and the aboveground condition (i.e., size) of red pines appeared to be influenced by the surrounding Japanese cypress (Chamaecyparis obtusa). Smaller P. densiflora exhibited lower fine root biomasses, shorter root lengths, and lower root tip densities, but longer specific root lengths and higher specific root tip densities relative to larger pines. These results suggest that P. densiflora may adjust the morphological traits of fine roots to the different conditions in biomass allocation to fine roots of individuals with different aboveground growth.     

Relationships of stem surface area to other stem dimensions for Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis> D. Don) and Japanese cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> Endl.) trees

I investigated the relationships between stem surface area outside bark and other stem dimensions for Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Endl.) trees. The stem dimensions used here were the basal area and the product of diameter at breast height (dbh) and total tree height. The regression equation of the stem surface area s against basal area g was s = 184.216g for the cedar trees and s = 156.878g for the cypress trees. The slope of the equation was significantly different between the two species. For the same dbh, the cedar trees tended to have a higher total tree height than the cypress trees. The cedar trees also had a larger surface area of relative stem form than the cypress trees. These results indicated that the difference in the slope was produced by the differences in both the stem slenderness and tapering between the two species. On the other hand, the regression equation between the stem surface area and the product of dbh and total tree height dh was s = 1.937dh for the cedar trees and s = 1.921dh for the cypress trees, whereas no significant difference in the slope was found. The obtained slopes for the cedar and cypress trees seemed to be in accord with that for other coniferous species reported in earlier studies, suggesting that the variation in the slope among coniferous species would be small. The estimation from the basal area would provide a simpler means for estimating the stem surface area and would be useful in obtaining an approximation of the surface area. By contrast, the estimation from the product of dbh and total tree height would provide a more accurate and precise estimate as well as a wider applicable range, i.e., a parameter for physiological growth models. In conclusion, it could not be judged which regression equation examined in the present study was superior to the other, and thus it was important to select an appropriate equation depending both on the purpose and on the time and labor available.     

Ring characteristics and screw withdrawal resistance of naturally regenerated <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> var. <Emphasis Type="Italic">formosana</Emphasis> trees

The ring characteristics and screw withdrawal resistance (SWR) of naturally regenerated Taiwan yellow cypress (Chamaecyparis obtusa var. formosana) trees were explored. Significant differences in average ring width (RW), earlywood width, latewood width, ring density (RD), earlywood density (ED), latewood density (LD), highest density (D_max), lowest density (D_min), latewood percentage (LWP), and SWR were observed between trees, rings (SWR excluded), and tree height positions. The RW components in the radial direction increased from the pith outward to about the 3rd to 5th ring and then decreased to about the 25th ring; it was almost constantly sustained toward the bark side. The RD in the radial direction slowly decreased from the pith outward to the bark side. Average ring width and ring density were significantly affected by the various tree growth rates, radial ring numbers, and tree height positions. ED, LD, D_max, D_min, and LWP were the most important factors determining the overall RD. RW did not correlate with tree RD. SWR is correlated with ED, RD, D_min, LWP, and intra-ring density variation (IDV). Thus, the SWR can be used to predict wood density and in nondestructive evaluation of a living tree.     

Aboveground productivity of an unsuccessful 140-year-old <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> plantation in northern Kyushu,Japan

We measured the aboveground biomass, biomass increment and litterfall production of a 140-year-old, abandoned Cryptomeria japonica plantation in order to infer the effects of topography on biomass production. The plantation was unsuccessful and the naturally regenerated broad-leaved trees contributed 93.4% (374.2 Mg ha⁻¹) of the total aboveground biomass (400.2 Mg ha⁻¹). Comparing between different slope positions, aboveground biomass decreased downslope corresponding to the decrease in broad-leaved tree biomass. The biomass of C. japonica did not vary with slope position. Biomass increment and litterfall production of the broad-leaved trees also decreased downslope. However, litterfall production per unit biomass and aboveground net primary production per unit biomass increased downslope. Results of a path analysis showed that biomass increment of C. japonica decreased with increasing topographical convexity, whereas biomass and litterfall production of broad-leaved tree increased. Litterfall production of broad-leaved tree decreased with increasing biomass of C. japonica, suggesting that, despite their small biomass, the presence of residual C. japonica may have negative effects on the distribution and productivity of the broad-leaved trees. Our results indicated that total aboveground biomass of the study site was comparable to that of old-growth C. japonica plantations. We inferred that the variation in aboveground biomass of the broad-leaved trees was largely determined by the topography, while their productivity was affected by interactions with planted C. japonica.     

A weeding-duration model for <Emphasis Type="Italic">Larix kaempferi</Emphasis> plantations in Hokkaido,northern Japan

In this study, a weeding-duration model for Larix kaempferi plantations was developed that employs a generalized linear model. The number of years that weeding is necessary is the response variable, and elevation, slope, maximum snow depth, annual precipitation, geological type, soil type, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geological type, soil type, slope aspect, and vegetation type are categorical data. We assumed a Poisson distribution for the response variable. The link function was log. Among the models that could be developed from these variables, we chose the model with the smallest Akaike’s information criterion (AIC). The weeding-duration model can be written as follows: years that weeding is necessary = Exp (−0.0172833 × site index + 0.0014053 × maximum snow depth (cm) + 1.7417731). The results of this study imply that weeding of Larix kaempferi plantations is needed for more years as the maximum snow depth increases and fewer years as the site index increases. This model is useful for cost–benefit analyses of afforestation or reforestation with Larix kaempferi.     

Physiological effects of touching hinoki cypress (<Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis>)

This study aimed to clarify the physiological effects of touching hinoki cypress (hereinafter called “hinoki”) (Chamaecyparis obtusa) wood with the palm of the right hand on brain activity and autonomic nervous activity. Twenty-two female university students (mean age 21.1?±?0.2 years) participated in the study. As an indicator of brain activity, oxyhemoglobin (oxy-Hb) concentrations were measured in the left/right prefrontal cortex using near-infrared time-resolved spectroscopy. Heart rate variability (HRV) was used as an indicator of autonomic nervous activity. The high-frequency (HF) component of HRV, which reflected parasympathetic nervous activity, and the low-frequency (LF)/HF ratio, which reflected sympathetic nervous activity, were measured. Plate (300?×?300 mm) of uncoated hinoki was used as tactile stimulation. Marble was used as a control material. After sitting at rest with their eyes closed, the participants touched the materials for 90 s with their eyes still closed. The results showed that tactile stimulation with hinoki significantly decreased oxy-Hb concentration in the left prefrontal cortex and increased ln(HF) reflected parasympathetic nervous activity compared with marble. In conclusion, our study showed that touching hinoki wood with the palm calms prefrontal cortex activity and increases parasympathetic nervous activity, thereby inducing physiological relaxation.     

Neuropharmacological activities of phytoncide released from <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>

Forest-air bathing and walking (shinrin-yoku) is beneficial to human heath. In this study the phytoncide (volatile compounds) released from Cryptomeria japonica plantation forest was characterized by using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The main volatile compounds were α-pinene (19.35%), β-myrcene (16.98%), d-limonene (15.21%), and γ-muurolene (7.42%). Furthermore, the neuropharmacological activity of the essential oils from leaves of C. japonica (ECJ) was evaluated by several animal behavior tests. ECJ could prolong the sleeping phase of ICR (imprinting control region) mice in the pentobarbital-induced sleeping time model. Furthermore, both EJC and one of its monoterpenes, d-limonene, possessed potent anxiolytic and analgesic activities based on the results obtained from elevated plus maze and writhing tests. The volatile compounds released from C. japonica provide relaxing and stress-relieving effects on mice, and further study on the effect of phytoncide on humans is worthwhile.     

Early evaluation of growth traits of <Emphasis Type="Italic">Larix kaempferi</Emphasis> clones

Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection. To evaluate the early selected time for Larix kaempferi, tree height and diameter at breast height of 57 L. kaempferi clones were measured over many different growth years. The results indicated that, except for age × clone interaction for diameter at breast height (P = 0.741), there were significant differences among all variation sources (P < 0.01). The coefficient of phenotypic variation ranged from 14.89 to 35.65% for height and from 19.17 to 23.86% for diameter at breast height in different growth years. The repeatability of height and of diameter at breast height among clones was high, ranging from 0.6181 to 0.8531 (height) and from 0.8443 to 0.8497 (diameter at breast height), in different growth years. There were significant positive correlations between all pairs of growth traits except between height in the 2nd growth year and height in the 30th growth year; and between height in the 2nd growth year × diameter at breast height in the 30th growth year. With a comprehensive evaluation method and a selection ratio of 10%, L65, L1, L62, L9, L15, and L78 were selected as excellent clones in the 30th growth year. Their average values of height and diameter at breast height were 9.81 and 16.57% higher than the overall average, representing genetic gains of 6.46 and 13.99%, respectively. This study provides a theoretical foundation for the genetic improvement of L. kaempferi.     

Longitudinal shrinkage variations within trees of sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) cultivars

The longitudinal shrinkage variations within trees and the relationship with density, microfibril angle, and modulus of elasticity were examined for five sugi cultivars selected for different within-tree distributions of density, microfibril angle, and modulus of elasticity. The cultivars showed significant differences in longitudinal shrinkage and in its within-tree distribution. The within-tree distributions were categorized into two types: (1) large values of longitudinal shrinkage near the pith that decreased with height and from pith to bark, (2) small values of longitudinal shrinkage near the pith that increased slightly from pith to bark. There were strong relationships between longitudinal shrinkage and microfibril angle, and modulus of elasticity, with large values of longitudinal shrinkage associated with large microfibril angle and low modulus of elasticity. Sugi exhibited large variation in longitudinal shrinkage within stem and among cultivars, with the variation strongly affected by microfibril angle. Part of this article was presented at the 56th Annual Meeting of the Japan Wood Research Society, Akita, Japan, August 2006     

Aboveground biomass and nutrient allocation in an age-sequence of <Emphasis Type="Italic">Larix olgensis</Emphasis> plantations

Biomass and nutrient (N, P, K, Ca, Mg) stock in various aboveground tree components (stemwood, stembark, branches and leaves) were quantified in an age sequence of pure Larix olgensis planta- tions (20, 35, 53 and 69 years old) in Northeast China. The results show that the aboveground biomass allocation in various tree components was in the order of stemwood (62%-83%), branches (9%-21%), stembark (7%-11%) and leaves (1%-6%) for all stands. The proportion of stemwood biomass to total aboveground biomass increased whereas that of other tree components decreased consistently with stand age from 20 to 53 years old, but kept relatively constant with stand age from 53 and 69 years old. The nutrient allocation in various tree components generally followed the same pattern as the biomass allocation (i.e. stemwood > branches > stembark > leaves). The proportion of nutrient stock in leaves to total aboveground nutrient stock decreased consistently with increasing stand age, while that in stemwood increased with stand age from 20 to 53 years old but then decreased from 53 to 69 years old. The rate of nutrient removal for stands was estimated at different stand ages under different logging schemes, showing that the rate of nutrient removal would be unchanged when the rotation length was shortened to 20 years by the harvest of stem only, but greatly increased by the harvest of total aboveground biomass. The rate of nutrient removal would be a considerable reduction for all elements by debarking, especially for Ca.     

Effects of altitudinal gradient on species composition of naturally regenerated trees in <Emphasis Type="Italic">Larix kaempferi</Emphasis> plantations in central Japan

Species composition and community structure of naturally regenerated trees in Larix kaempferi plantations and natural forests were compared in relation to altitudinal gradient. Fifty-nine L. kaempferi plantations and 26 natural forest stands including old-growth and secondary forests were selected from 1300 to 2000 m a.s.l. in Mt Kushigata of central Japan. Vegetation plots (10 × 10 m) were established in each stand (85 plots in total). Species composition differed significantly between forest types, particularly on high altitude plots. Some species were significantly biased to natural forests, while no species were biased to plantations. Although some species that responded significantly to altitude were common to both forest types (e.g., Acer ukurunduese, Castanea crenata, and Fraxinus lanuginose f. serrata), some differed between forest types (e.g., Fagus japonica, Prunus maximowiczii, and P. nipponica). Thus, plantation management altered species responses to altitude. Altitude should be considered when planning and carrying out forest ecological restoration in plantations, because species composition of naturally regenerated trees has already been changed by past plantation management. In particular, attention should be paid to ecological restoration at high altitude.     

Tangential and radial shrinkage variation within trees in sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) cultivars

The transverse shrinkage variation within trees was examined for five sugi cultivars. The within-tree trends of tangential shrinkage (α _T) were different by cultivar, whereas radial shrinkage (α _R) increased from pith to bark in most cultivars. The tangential/radial shrinkage ratio (α _T/α _R) decreased from pith to bark in most cultivars, because the radial variation of α _R was larger than that of α _T. The cultivars showed significant differences among cultivars in α _T, α _R, and α _T/α _R, but the difference among cultivars for α _T/α _R was smaller. The relationships between transverse shrinkage and microfi bril angle (MFA), basic density (BD), tree ring parameters, and modulus of elasticity were examined. The α _T and α _R showed positive relationships with BD, latewood percentage, latewood density, and modulus of elasticity, and negative relationships with MFA and ring width. The relationships with earlywood density were weak. Sugi exhibited variation in transverse shrinkage within stem and among cultivars, with the variation affected by MFA, density, and tree ring parameters. Part of this article was presented at the 56th Annual Meeting of the Japan Wood Research Society, Akita, Japan, August 2006, and the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, Japan, August 2007     

Delignification of cell walls of <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> during alkaline nitrobenzene oxidation

To clarify the behavior of whole lignins in wood cell walls during alkaline nitrobenzene oxidation, the delignification process from cell walls in normal and compression woods of Chamaecyparis obtusa Endl. (Cupressaceae) was observed using ultraviolet and transmission electron microscopies. The lignin content conspicuously decreased to around 10% after 35min in normal wood. The lignin content in compression wood finally leveled off at aroumd 10% after 50min. In gel filtration of oxidation products in ethyl acetate, a high molecular weight fraction was prominent in extracts from the early stage of the reaction. As the oxidation progressed, the high molecular weight fraction became less prominent in both normal and compression wood. Changes in the weights of cell wall residues during reaction indicated that approximately half of the components other than lignin were also removed from the cell walls. This shows that the majority of lignin with relatively high molecular weight is removed from the cell walls together with polysaccharides in the early stage of the reaction and that further oxidative degradation occurs in solution in later stages. Only a small amount of the lignin with low molecular weight could be analyzed by gas chromatography.Parts of this report were presented at the 47th (Kochi, April 1997) and 48th (Shizuoka, April 1998) Annual Meetings of the Japan Wood Research Society, and at the Lignin Symposium, Sapporo, October 1997     

Bioremediation of CCA-treated wood by brown-rot fungi <Emphasis Type="Italic">Fomitopsis palustris</Emphasis>, <Emphasis Type="Italic">Coniophora puteana</Emphasis>, and <Emphasis Type="Italic">Laetiporus sulphureus</Emphasis>

This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.An erratum to this article can be found at     

Cesium absorption through bark of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

Absorption of radiocesium (¹³⁷Cs and ¹³⁴Cs) through bark, and its subsequent translocation into wood and needles, has been suggested as a potential source of tree contamination, but the process is not well understood. Field experiments were conducted to confirm whether Cs could enter a Japanese cedar tree through the bark and how Cs moves within a tree. Stable Cs (¹³³Cs) was applied to the bark at 1.2-m height on 10- and 26-year-old Japanese cedars. The ¹³³Cs concentrations were determined in the bark, sapwood, and heartwood (for 26-year-old cedar only) of stem disks from several heights, as well as in current-year needles from the canopy. The ¹³³Cs concentrations were considerably higher in the sapwood and heartwood of stem disks from 1.2-m height in treated trees than in untreated trees, suggesting that ¹³³Cs penetrated the bark to enter the wood. The average ¹³³Cs concentrations were higher in the heartwood than the sapwood, indicating ¹³³Cs accumulation in the heartwood. High ¹³³Cs concentrations in the needles of treated trees implied acropetal movement of ¹³³Cs to actively growing organs. Our results demonstrate that Cs can enter Japanese cedar trees through the bark and that Cs is transported radially to the heartwood and vertically to the apex.     

Changes in water distribution in heartwood along stem axes in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>

 Three-dimensional distribution of water in the heartwood of Cryptomeria japonica D. Don was observed by soft X-ray photography. The within-tree variation in the distribution of “wet areas” (water-accumulated areas in heartwood) was enormous, as was the variation among trees. Although we found no universal pattern of changes in wet area distributions along the stem axes of all trees, similarities among individual trees within each cultivar and clone were observed. The difference between the two kinds of wetwood in C. japonica – genetically defined wetwood and secondarily induced wetwood – is discussed, as is the use of soft X-ray photography in Japanese tree breeding programs. Received: December 21, 2001 / Accepted: May 1, 2002 Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Kumamoto, Japan, April 1996 Correspondence to:R. Nakada