To examine the regeneration process of broadleaved trees in planted larch (Larix kaempferi) forests, we investigated stand structures, species compositions and age distributions of broadleaved trees related to thinning histories, and species compositions of buried viable seeds in six planted larch forests located in the southern part of the Ishikari lowlands in Hokkaido, northern Japan. Density of broadleaved trees was lower in planted larch forests with dense sasa (Sasa spp.), and it was assumed that sasa inhibited the regeneration of broadleaved trees in planted larch forests. It was also assumed that thinning positively influenced the regeneration of broadleaved trees in the plantations, because the density of the trees increased after thinning. The number of species of broadleaved trees increased stepwise with thinning, and especially, the number of gap-dependent species markedly increased after the first thinning in the planted larch forests. Species composition of buried viable seeds was not similar to species composition of broadleaved trees. It was guessed that the seeds contributed little to the regeneration of broadleaved trees in planted larch forests, and yet more detailed examination of buried viable seeds in will be needed. Consequently, it was concluded that sasa negatively influenced the regeneration of broadleaved trees, and that thinning increased both density and species diversity of the trees in planted larch forests. Furthermore, it was suggested that the timing of the regeneration and species composition of broadleaved trees in planted larch forests are closely related to regeneration habits of the trees.

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Periodic annual net increment of stand volume and stand structure dynamics were analyzed by using data collected in long-term monitoring during a 77-year period in a sugi (Cryptomeria japonica) natural forest located in Akita Prefecture, Northeastern Japan. Forest age was estimated at the end of the monitoring period to be 244 years. The research forest was thinned twice during the monitoring period, first at 168 years old and again at 190 years old. The periodic annual net increment of stand volume peaked at about 10 years after each of the thinning operations. The increase in volume growth of individual trees following each thinning operation may be seen as a cause of the peaks in periodic annual net increment of stand volume. After each of the two peaks mentioned, the periodic annual net increment markedly decreased from 32.2 to 6.1 m³ha^-1yr^-1 just before the second thinning operation, and decreased from 14.9 to 3.7 m³ha^-1yr^-1 at the end of the monitoring period. Both thinning operations had a strong impact on the distributions of DBH and tree height; the research forest transformed from a multi-storied forest to a single-storied forest. The tree height growth declined earlier than basal area growth. Therefore, the stem volume growth of old-growth trees is produced by basal area growth rather than height growth.

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An optimum allocation of selection weight on the traits that were related to carbon storage in the stem of sugi was investigated to establish criteria for choosing plus tree clones suitable for carbon storage. The traits examined in this study were tree height, diameter at breast height (DBH), basic density, and carbon content per unit weight. In the case of single trait selection, the selection for tree height would bring about a good amount of gain in both tree height and DBH due to strong genetic correlation. Relative gain in carbon content, though the heritability was high, was negligibly small due to its very low coefficient of variation. Selection for basic density would bring about comparable genetic gain, while it resulted in negative responses in growth traits. An optimum allocation of selection weight for tree height and basic density in selection index was examined by changing their economic weight step by step so as to maximize the expected carbon storage potential of the selected population under the standard selection intensity: selection for the top 38% clones. The carbon storage potential was found to be maximized when the index was I=2.8×(Tree height)+18.87×(Basic density) where the increase in the selected population was 21.4% greater than the population mean. Clones with high index value tended to put more weight on tree height than on basic density.

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Being the most extensively forested region of the world, the carbon budget of the Siberian boreal forest is one of the important subjects of global concern. This study was conducted to quantify leaf area index (LAI), one of the significant factors controlling terrestrial carbon budget, over an extensive range in Siberia as well as to propose a new method of LAI estimation using airborne laser altimetry. Along a 200-km transect set up along the Bakhta River, a tributary of the Yenisey in central Siberia, airborne laser altimetry was conducted to obtain a vegetation profile, from which the distribution of LAI all along the transect was estimated on the basis of allometric relationship among LAI, standing timber stock and vegetation profile area, using ground-truth measurements of LAI and timber stock at ten sample plots laid out directly beneath the flight track. It turned out that the distribution of LAI is controlled not only by temperature which in turn is dictated by the altitude down from the Central Siberian Plateau to the alluvial flat of the Yenisey, but also significantly by the thickness of active layer on permafrost, which varies considerably both regionally and locally depending upon the topography. With the capability of measuring vegetation characteristics and topographic features simultaneously, airborne laser profiling should turn out to be a powerful tool for monitoring in an integrated manner the Siberian boreal forest and its environment threatened by the impending global warming.

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In order to shorten the period required to select sterile trees from the mating family of male-sterile Cryptomeria japonica D. Don lines, germinated male-sterile C. japonica seeds were planted in sphagnum-filled vinyl pots (width, 15 cm; height, 20 cm) in early December and incubated at 23°C until the end of March in the following year. In early April, the pots were moved to the greenhouse. The seedlings in pots were treated with 100 ppm gibberellin in early July to accelerate their development of male flowers, which were collected from each seedling during the middle of December and examined under a microscope at 50 × magnification to detect the presence of pollen. Tree height, basal diameter, number of female flowers, the number of clusters of male flowers, and branch spread were also examined. The form and flowering characteristics of the seedlings depended on the number of seedlings planted per pot. When five or more were planted per pot the seedlings were small and some produced no male flowers. Furthermore, under these conditions, fertile male flowers were sometimes mistaken for sterile flowers. In contrast, in pots with fewer than four seedlings, all male-fertile seedlings produced fertile male flowers. Therefore, the time required to identify male-sterile seedlings from the mating family of male-sterile Cryptomeria japonica D. Don lines can be shortened using the methods developed in this study.

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The relationships between characteristics of band and luminance and classification of the tree vigor of aged, large-diameter Japanese Red Pine was performed using high-resolution IKONOS satellite data. The digital number (DN) was higher with individual groups of healthy trees in all bands. Based on results of ANOVA, there was a significant difference in tree health at every band. The predominance of bands for classification of the tree vigor were band 4> band 2, band 3> band 1, in order. When tree health was diagnosed through discriminant analysis of the DN for individual bands in the amount of variance, discriminant accuracy improved with an increase in the amount of variance. Maximum discriminant accuracy was 81% between the group with the healthiest trees and the group with the least healthy trees, and the minimum was 56% between the group with the healthiest trees and the group with the second healthiest trees.

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The improvement cutting of coppice was carried out in heavy snow mountain slopes, together with planting and construction of a simple supporting structure for glide of snow cover. To clarify the effect of the operation, the distance of glide was measured, as well as the state of the sprouts from the cut coppice and the height growth of planted stock. After the operation, the distance of glide could be suppressed to approximately 2 m on the steep slope. This fact suggested the efficiency of the supporting works. Since stumps used as the supporting structure are sprouting, they can be effective for a long term. The height of planting stock exceeded the maximum snow depth after 5 years. The stock will be able to control the glide of snow cover if the survival rate and the growth rate maintain their present status.

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The stand structure of a secondary forest established on the Osaka group and related factors were analyzed. Twenty-seven quadrats were set in the forest, and every tree in those quadrats was measured. A cluster analysis conducted based on the results showed that there were two major stand types, Quercus serrata-dominated type and Pinus densilora-Ilex pedunculosa-dominated type. The former type did not exist at locations with harder soil including more gravel. Q. serrata included fewer older stems than P. densiflora, and known evidence showed that rare Q. serrata once existed on the study site. We conjectured that differences in the growth rate of Q. serrata according to the soil conditions caused the differences between two stand types in this secondary forest.

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To develop a method of quantitating oxytetracycline (OTC), which is being considered as a promising agent for the control of Elaeocarpus yellows, I measured OTC in the leaves by high performance liquid chromatography (HPLC). Leaves of Elaeocarpus sylvestris var. ellipticus were homogenized in McIlvaine buffer, and subjected to HPLC using a mobile phase of an imidazole buffer-methanol mixture (80:20), a 150×4.6mm I.D. Luna C₁₈ (2) column and a fluorescence detector. OTC was well separated and detected by this method. The recovery rate of the OTC added to leaf at sample preparation was nearly 90% and the linearity of the calibration curve was adequate. This method may be useful for determination of the OTC concentration in leaves effective against the phytoplasma responsible for Elaeocarpus yellows and not harmful to the plant as step toward developing a practical method of controlling the disease.

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In order to develop effective forest management practices which reduce fine sediment production and delivery, this paper reviews how forest operations can affect suspended sediment discharge. Cutting and unmanaged forest plantations have shown increases in suspended sediment delivery. Suspended sediment concentrations or annual yields increase following logging, and tend to gradually decline over a period of years. Road systems, such as forest roads, skid roads, and skid trails, are often sources of suspended sediment owing to mass failures or road-surface erosion. Logging activities can compact soils, thus impacting the soils' physical properties and delaying vegetation re-growth on the ground surface. In order to control sediment discharge and soil erosion, buffer strips of riparian forests should be carefully preserved and the area disturbed by forest operations should be minimized.

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