Windthrow factors in windbreaks in Bibai, Hokkaido, which was damaged by typhoon No.18 (max wind speed 21 m/s) in 2004, were analyzed. The windbreaks investigated were plantations of Picea abies, Larix leptolepis, Betula platyphylla, or Fraxinus mandshurica. Diameter at breast height (DBH) and the type of damage (e.g., “uprooted”, “snapped”, or “undamaged”) were determined for each tree in 21 quadrats. The vertical profile of soil hardness was also measured using a simplified dynamic cone penetrometer in each quadrat. The maximum moment of resistance against uprooting was measured by pulling the trunk of a standing tree laterally for each species to determine why the sensitivity to windthrow differed. The sensitivity to windthrow decreased in the order L. leptolepis>P. abies>B. platyphylla>F. mandshurica. The sensitivity to windthrow had a bell-shaped distribution with a peak at DBH=30 cm. L. leptolepis and B. platyphylla were more likely to be “uprooted”, while P. abies was more likely to be “snapped”. Soil hardness was not closely related to the sensitivity to windthrow. The moment of resistance against uprooting was higher for F. mandshurica than for the other three species. The sensitivity to windthrow might be related to tree height and leaf mass, in addition to the moment of resistance against uprooting.

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Monochamus alternatus adults were artificially inoculated with the entomopathogenic fungus, Beauveria bassiana, just after emergence, and reared individually with a Pinus thunbergii sapling in an outdoor cage. The infection resulted in high adult mortalities both at 7 and 14 days after emergence and a significant decrease in adult longevity from 36.5 to 7.5 days. The infection also decreased maturation feeding activities; the percentage of adults which ceased maturation feeding within 7 days after emergence increased from 38 to 92%, the total amount of maturation feeding decreased to less than 1/10, and the percentage of saplings with maturation feeding scars decreased from 81 to 61%. As a result, the mortality of saplings decreased from 77 to 51%. However, the effects of the infection on the percentage of saplings with feeding scars and the mortality of saplings were not significant at 7 days after infection. These results indicate that the infection of M. alternatus adults with B. bassiana can control pine wilt disease, although the effects of the infection become evident after a certain period of time from the infection. Thus, the infection might be less effective in areas where the pine wood nematode departs from M. alternatus adults soon after their emergence from the logs.

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There are seven seed distribution zones for sugi (Cryptomeria japonica) in Japan. To examine validity of seed and seedling transfer over the boundary of seed distribution zone within the same prefecture, we investigated survival rate and tree height using the progeny testing data of plus-trees clones which were planted in two seed distribution zones in both Fukushima and Gifu Prefectures which have both the second and third seed distribution zones. There was significant genotype by environment (GE) interaction for survival in Fukushima Prefecture, but not in Gifu Prefecture. There was no significant GE interaction for tree height in either prefecture. No clones selected in the second zone showed a significant correlation between snowfall and survival rate or tree height, but some clones selected in the third zone showed a significantly negative correlation between snowfall and both survival rate and tree height in Fukushima Prefecture. Some clones selected in both second and third zones showed a significantly negative correlation between snowfall and both survival rate and tree height in Gifu Prefecture. Survival and tree height of plus-tree clones in response to snowfall differed between Fukushima and Gifu Prefectures, and these results suggest that the regulation of seed and seedling transfer between two seed distribution zones was sufficient for Fukushima Prefecture, but insufficient for Gifu Prefecture.

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This study aimed to estimate forest resources and identify individual trees methods to apply forest management systems. Hence, we assessed the potential application of LiDAR (Light Detection and Ranging) data for reproducing the crown of sugi (Cryptomeria japonica D. Don) and hinoki (Chamaecyparis obtusa Endl.) in plots with varying densities. Initially, we measured the forests canopy by LiDAR, and then felled a sample tree within each type of forest and measured its parameters (crown diameter, crown length, and tree height) in detail. Subsequently, we developed wire frame models of crowns by using field data and LiDAR data realistically and numerically. As a result, the crown reproduced using the airborne LiDAR data was similar to the model fabricated using realistic values. The estimation error for hinoki was greater than that for sugi because of the difference in crown and canopy structures-crown shape of sugi is like conic type, that of hinoki is cylindrical. Further, it was difficult to detect subcanopy structures such as suppressed tree crowns; however, dominant tree crowns could be detected. Thus, reproduction of sugi and hinoki stands using airborne LiDAR proved to be realistic.

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We investigated the morphological and genetic factors affecting the rooting ability of cuttings and the shoot production of hedges of Pinus thunbergii by performing two different experiments. The effect of cutting size on rooting ability was investigated by using shoot cuttings obtained from five hedges (5∼6 years old). The shorter and thinner cuttings tended to show better rooting ability, and the rooting ability was different among individual hedges. In order to clarify the factors affecting the numbers and the sizes of the shoots obtained from the hedges, we measured several morphological traits of the shoots and the pruned branches in three 4-year-old hedges for each of the five half-sib families. A stepwise regression analysis suggested that the number of shoots per pruned branch was affected by the length of sprouting zone and the diameter of the pruned branch. The sizes of the shoots were most affected by the diameter of the pruned branch. Nested ANOVA showed that the number of shoots per pruned branch, the diameter of the pruned branch, and the length of the sprouting zone significantly varied among the families. These results suggested that family selection can improve the numbers of shoots in P. thunbergii hedges.

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We studied the propagation of aged Fagus crenata trees, which is regarded as to be almost impossible, using cuttings of current-year shoots. The shoots were collected from seven trees with a mean diameter of 75.6 cm. The shoots collected from four trees completed the shoot elongation, whereas those from the other three had completed the bud-flush phase but were still in the elongation phase. Sampled shoots were transported paying attentions to dehydration, and they were placed in a water bath with running water for 48 h, and then, treated with 100 ppm IBA for 24 h. All shoots still not completed elongation phase died before planting, indicating that shoots not completed elongation phase would not suitable for cutting propagation. By covering the plant bed with nonwoven cloth and 70%-shading black cheesecloth shade, the condition of the plant bed was kept at such high humidity of 97.9% and mean temperature of 24.1 during the nurturing period. Of the 94 planted shoots, 40.4% rooted, and 41.5% callus-formed. Thus, higher proportion of rooted cuttings was obtained using the current-year shoots of aged F. crenata trees, and it would mean that cutting propagation is possible even for aged F. crenata trees.

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To improve vegetative propagation of progeny seedlings of nematode-resistant clones of Pinus thunbergii, we investigated the effect of different concentrations of indole-3-butyric acid (IBA), 1-naphthaleneacetic acid (NAA), and uniconazole-P (UNI) and their combination on the rooting of cuttings from 7-year-old seedlings of 5 families. When cuttings were treated using solutions containing different concentrations (0∼10,000 mg/L) of either IBA or NAA, the mean rooting percentage was the highest at a solution containing 5,000 mg/L IBA. On the other hand, none of the solutions containing of UNI (0∼100 mg/L) promoted the rooting of cuttings. In contrast, the rooting percentage of cuttings treated with both solutions of 5,000 mg/L IBA and 100 mg/L UNI was significantly higher than that of cuttings treated with only IBA. The rooting percentages of difficult-to-root families tended to increase when both solutions of IBA and UNI was used. These results suggest that a combination of UNI and IBA was effective to promote rooting of P. thunbergii cuttings.

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The large scale planting of cultivated species such as Prunus yedoensis “Someiyoshino” can disturb the genetic structure of wild Prunus species. We developed genetic markers to detect the gene flow from P. yedoensis to wild Prunus species. The self-incompatibility gene (S-gene) was used as the genetic markers because it is highly polymorphic. We designed the PCR primer pairs to amplify the two S-alleles of P. yedoensis specifically. Although the genetic markers developed in this study almost successfully detected the pollen-mediated gene flow from P. yedoensis, it seemed difficult to accurately discriminate the gene flow from the trees of wild Prunus species, which already had one or two copies of same S-alleles with P. yedoensis’s. If combined with the SSR markers, samples with genome surely derived from P. yedoensis could be determined. Thus, our approach based on the S-locus polymorphism has a practical use, and the developed genetic markers are powerfully available as a molecular tool to evaluate the dispersal pattern of the genome derived from P. yedoensis.

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A pair of SNP (single nucleotide polymorphism) markers has been developed as a highly reliable management tool for the conservation of Zao larch genetic resources. The DNAs from Zao larch and Japanese larch were amplified and sequenced with primers designed on the basis of 17 RAPD (random amplified polymorphic DNA) fragments specific to either Zao larch or Japanese larch. By comparing these sequence data, we investigated SNPs in which Japanese larch showed different genotype from Zao larch, and SNP primers that distinguish SNP types were designed. Using the 3 previously reported SCAR (sequence characterized amplified region) markers and these 2 SNP markers together, it was possible to discriminate genuine Zao larch from the hybrid of Zao larch and Japanese larch with a misidentification probability of 2.28×10⁻⁴. Furthermore, these 5 markers were used to verify 294 progenies from the natural Zao larch population, and it was confirmed that all of them were genuine Zao larch.

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Although sap flux measurement is one of the most robust techniques for stand-scale transpiration estimates, its applicability to bamboo is unclear. Ultimately we aim to establish a method for sap flux-based stand-scale transpiration estimates in a bamboo forest. This study focused on establishing a method for individual-scale transpiration estimates. We conducted sap flux measurements using hand-made 1-cm length sensors, and water absorption measurements in cut-bamboo. The sensors could detect water uptake in individual plants (i.e., sap flux in moso bamboo). The diurnal changes in sap flux density reasonably well corresponded to those in water absorption. We found there was an underestimation of whole-tree water use with the 1-cm Grainer sensor; thus we suggested a modified equation for the calculation of sap flux density. In this study we could estimate individual-scale transpiration in moso bamboo using sap flux measurements.

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