The classification of forest type by aerial photo interpretation is usually based on color and texture of the image, and also from knowledge of the relationship between vegetation and topography. In this study, use of topographic factors for object-based forest type classification with high resolution satellite IKONOS imagery was examined to improve efficiency and accuracy of making maps of forest types. Two methods, one using spectral features only and the other combining spectral features and topographic factors, were applied to classify the forest in the eastern part of Kyoto City. Using topographic factors (distance from ridge line and distance from thalweg) with spectral features improved the accuracy of classification significantly at the 1% significance level measured by the Kappa coefficient. In the region where the difference in elevation is small, the spatial pattern of forest distribution is affected not by the temperature change with elevation but by the difference in soil moisture condition according to topographic position (ridge or valley). Consequently, the use of topographic factors would improve the accuracy of forest type classification.

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Past management, stand structure and tree quality composition were investigated in six stands of about 100-year-old Chamaecyparis obtusa plantations, to understand the effects of their respective thinning histories. The stand which had not been thinned for about 60 years since the previous thinning showed highest tree density (843 trees ha⁻¹) and highest stem volume (1,298.9 m³ ha⁻¹), and tree density and stem volume tended to decrease as the frequency of thinning increased. Maintaining lower tree density, that is, less than 500∼1,000 trees ha⁻¹ from the early stage of the plantations, may enable the establishment of an old-aged coniferous plantation with high stem volume, without additional thinning. On the other hand, regarding tree quality composition, planted trees belonging to larger size-classes showed a higher proportion of higher quality trees in all stands. However, lower quality trees were observed even in the stands which had been subjected to multiple thinnings. Tree density of the higher quality trees was constant, at 100∼150 trees ha⁻¹ in all the stands, regardless of the thinning history. These results suggest that the thinning in the study stands had not improved the quality composition of the stands. The data in this study could not provide much background information about this, they may nonetheless be important for establishing old-aged coniferous plantations composed of higher quality trees by thinning lower quality trees at the early stage of the plantations.

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The effect of mass mortality of oak trees, caused by the fungus Raffaelea quercivora, on the stand structure of a broadleaved secondary forest was investigated in a stand located in northern Kyoto City, in mid-western Japan. In the study stand after the epidemic, Ilex pedunculosa was the dominant species (basal area), followed by Fagus japonica, Quercus crispula, Acanthopanax sciadophylloides, and Magnolia salicifolia. More than half the Q. crispula individuals died during the epidemic. The number of dead Q. crispula trees suggested that the species would have been dominant in the tree layer before the epidemic. Individuals closer to the epidemic source and larger individuals suffered the highest mortality. M. salicifolia, A. sciadophylloides, and F. japonica had many stems expected to regenerate in the gaps resulting from death of Q. crispula trees, and these species are predicted to become more dominant in the tree layer at least in the short term. Hamamelis japonica var. obtusata and I. pedunculosa are also predicted to become more dominant in the middle and shrub layers.

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A control diagram of crown and stem form was attempted to construct based on the analysis of relationships among several stand characteristics. The data was collected from 32 young even-aged stands of Cryptomeria japonica. When stem length from top to a definite diameter (x) and that from top to DBH (D) were abbreviated as L_x and L_B respectively, the correlation between L_x/x and L_B/D became stronger with increase in x, although the data scattering was wide. Lower correlation at smaller x indicated that the stem shape above a certain diameter was similar despite difference in the L_B/D ratio. A linear regression was established between both ratios for each x. Furthermore, the relationship between the reciprocal of mean tree height/mean DBH ratio and the relative-spacing index (S_R) could be also approximated by a linear regression, resulting in a mathematical expression of mean DBH by both stand density and mean tree height. From these regressions, L_x could be expressed as a function of stand density and mean tree height. By combining a clear length model to these relationships, a diagram showing relationships among stand density, clear length, crown length ratio, and definite diameter height could be obtained for each tree height class.

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This study analyzed the production structure, factor substitutability and technological change of sawmill industry in Japan. Translog cost function was employed to achieve the objectives using annual data of sawmill output and three inputs: material, labor and capital from 1970 to 2004. Six models, encompassing different restrictions on the translog cost function, were applied to determine the production structure. And the general functional form was selected, which reveals the inappropriateness of the existing research based on the Cobb-Douglas or CES production function. All inputs in the sawmill industry are inelastic substitutes each other, which indicate that the industry has limited options to make input adjustment with respect to changes in relative input prices. There exists the economy of size in the sawmill industry, which exhibits the need for concentration of industry to reduce the production cost. Technological changes are material-neutral, labor-saving and capital-using. Material-neutral technological bias is thought to be one of the factors affecting the depression of the sawmill industry. Total factor productivity growth had been decreased infinitesimally. The technological progress to diminish the cost seemed to be dominated by the negative scale effect. Consequently, the sawmill industry needs to restructure its production structure to increase its productivity.

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We investigated tree population dynamics over a period of 10 years in a warm-temperate evergreen broadleaved secondary forest established on steep topography to examine the effects of topographic position and coppice-stand structure on typhoon damage to trees. All species in this site showed a higher proportion of direct typhoon damage such as snapped or uprooted stems on the lower slope than other slope positions, suggesting that vegetation on the lower slope is more likely to suffer from typhoon damage, probably due to low stability of the soil surface. This effect is considered to be a factor determining the low tree density on the lower slope. While the proportion of snapped or uprooted stems in the canopy layer was high, it was even higher in the understory, indicating that the type of typhoon damage differed between layer positions. Differences in typhoon damage between the major component species at this site were consistent with previous studies in old-growth forest. Moreover, differences in typhoon damages between four out of the five main species were not influenced by topographic position and coppice-stand structure; rather, they directly reflected species-specific factors related to resistance to typhoon damage, such as wood density.

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To demonstrate the seasonality of sprouting characteristics in Robinia pseudoacacia, we investigated sprout dynamics in Bibai, Hokkaido, northern Japan, over three growing seasons after the cutting of above-ground parts in May, June, or August 2004. Treatment season influenced growth in height for three consecutive growing seasons. Height growth tended to be higher for the May treatment and lower for the August treatment. The height growth for the same treatment season was consistently higher in Minami-Bibai stand than in Bannosawa stand. The number of sprouts decreased quickly and death of parent stumps, defined as the disappearance of living sprouts, was mainly observed between fall 2005 and spring 2007. Statistical analyses showed the dependency on treatment season for the sprout height and death of parent stumps. Death of parent stumps was also dependent on sprout height at the previous investigation. The volume of sprouts in 2007 was lowest in the August treatment. These results suggest that cutting the above-ground parts of R. pseudoacacia during high summer is effective for the removal of this alien species.

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We investigated the effects of deer browsing on broad-leaved tree invasion after heavy thinning (47.5∼71.2% reduction in stem density) in fenced and unfenced plots in conifer plantations with a high population of sika deer (Cervus nippon). In fenced plots, a number of broad-leaved trees, which comprised mainly pioneer species, invaded and grew well after thinning; further, they exhibited a high survival ratio. However, in unfenced plots, the number of broad-leaved trees that invaded was lesser than that in fenced plots, and they exhibited a low survival ratio. Only a few broad-leaved trees survived for 2 years after thinning in unfenced plots. Thus, these results suggest that deer browsing strongly inhibited the invasion of broad-leaved trees after thinning. The deer density levels affecting broad-leaved tree invasion after heavy thinning should be evaluated, and easy methods to prevent the concentration of deer populations in thinned stands should be developed. Such studies will help achieve the conversion of conifer plantations to mixed conifer—broad-leaved forests in locations with high deer populations.

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Biotechnology in forest tree breeding research in Japan is summarized including some important research held in abroad. In DNA analysis it is very important to select adequate kind of marker for each purpose. Methods and current status of marker aided selection and quantitative trait locus (QTL) analysis are discussed. As somatic embryogenesis is a promising method in tissue culture, its research process in Japanese tree species is summarized. Genetic modification system in Japanese cedar and Japanese cypress is introduced. The future of tree breeding using biotechnology is discussed.

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