Methods that can be used for predicting the merchantable volume produced from crooked trees have not yet been established. We developed a method that can be used to predict merchantable volume and volume ratios based on log grade. This method introduces a system of classifying stem crookedness into five classes using visual observation. Data from a total of 443 sugi stems were used to prepare equations for calculating merchantable volume and volume ratios based on log grade. The log grading rules employed here take into account defects such as crookedness, knots and decay and classify timber into three grades (i.e., A, B, and C) by which logs can be grouped according to length, diameter and crookedness. The merchantable volume equation uses stem crookedness classification as an explanatory variable and showed considerable improvement when compared to merchantable volume equations based on taper curve equations. The equations for volume ratio based on log grade could not well explain volume ratios of logs graded ‘A' or ‘B', but could explain volume ratios of logs graded ‘C' reasonably well. We confirmed that the models developed in this paper could predict log yield and revenue produced from crooked trees with reasonable accuracy.

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In order to develop the rapid cultivation of potted seedlings of Alnus fauriei, we tried a method using the suspension of root-nodulating Frankia. The root nodules were collected from naturally growing seedlings of A. fauriei in seven places in Toyama Prefecture. We applied the suspensions to new seedlings after germination. The nodulation rate and the seedling growth differed depending on the nodule sources used in inoculating A. fauriei. Using the root nodule suspensions derived from the seedlings with the best growth-performances, the nodulation rate was about 98% and the average size of the seedlings exceeded 50 cm at the beginning of October. This study demonstrated that A. fauriei seedlings grew to a size suitable for shipping within a period of six months, by the inoculation of Frankia spp. with high growth promoting effects as selected in this study, into germinated seedlings.

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A market-oriented industrial structure is required to stimulate the forestry and wood industry in Japan. Such a structure is necessary to develop the system of stable timber supply and appropriate forest management. We surveyed sugi (Cryptomeria japonica D. Don) plantations in Akita Prefecture to clarify the available timber volume based on current use and application. We also estimated the currently available and usable timber resources. The highest proportion (40%) of total timber volume was that of currently available timber. The total volume of forest stands was classified as available for harvest if the stands occurred on slopes with an incline of less than 20° and were less than 50 m from a road; these stands occupied about half of the total volume in all age classes. Judging from our results, we are convinced that present resources should be sufficient to meet demand for a decade from wood industries in Akita Prefecture. The sustainability of a long-term stable supply, however, is uncertain and additional studies would be needed. We anticipated that constructing the datasets of wood resources is conducive to implementation of appropriate forest management to meet demand for the forestry side. Such datasets are also conducive to the demand growth and new demand reclamation that is designed with the future of quality and quantity of resources for wood utilization in mind.

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In order to apply terrestrial LiDAR for phenotyping in forest tree breeding, various traits of stem were quantified and evaluated based on a point cloud obtained by ground-based three-dimensional laser measurements on a study site of F₁ individuals of Cryptomeria japonica plus trees. The point cloud of each individual stem was approximated by “stem circles", which are horizontal perfect circles arrayed per 10 cm height. Based on the point cloud and the stem circles, both height and diameter at breast height (DBH) of individuals were automatically estimated with high accuracy. The relative stem taper curve equation of the third order was approximated for each individual based on the stem circles. Stem volume of each individual estimated from the taper curve showed high correlation with one estimated from only tree height and DBH. Stem straightness was quantified in the two standardized methods and these methods were evaluated with stem straightness index investigated on the field. The relationships among these estimated traits were examiend using correlation coefficients. Of the ratio of additive genetic variance, the highest was stem straightness, followed in order by tree height, stem volume, DBH, and the coefficients of the relative stem taper curve. The usefulness of the analytical method for phenotyping in forest tree breeding was discussed.

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We examined the natural regeneration of trees after strip clear-cutting and scarification of a Larix kaempferi plantation in Iwate Prefecture, northern Japan. In the understory of the intact plantation, the density of broadleaf trees with DBH more than 3 cm was 693 stems/ha (500 individuals/ha) for canopy species such as Quercus crispula, Acer mono, and Magnolia hypoleuca, and the density was 236 stems/ha (207 individuals/ha) for subcanopy species such as Padus grayana, Morus australis, and Aria alnifolia. Fourteen years after clear-cutting and scarification, the density of multi-stem regenerating trees was 777 stems/ha (173 individuals/ha) for canopy species and 138 stems/ha (58 individuals/ha) for subcanopy species. The density of singlestem regenerating trees was 1,854 stems/ha for canopy species and 323 stems/ha for subcanopy species. Some single-stem-dominant species such as Betula maximowicziana, Betula platyphylla, L. kaempferi, and Pinus densiflora were not found in the understory of the intact plantation. It was concluded that clear-cutting facilitated sprouting from advanced trees and that scarification facilitated seedling emergence and establishment of light-demanding species. Therefore, combining clear-cutting with scarification has the potential to promote successful natural regeneration of various timber species and to convert a L. kaempferi plantation to mixed conifer-broadleaf forest.

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The effects of sika deer (Cervus nippon) on the forest dynamics after the mass mortality of oak trees in a broadleaved secondary forest in Kyôto City were investigated. The changes in the stem densities and basal areas before and after the occurrence of mass mortality and differences in woody species composition of the floor layer between the inside and outside of the gaps created by the mass mortality were examined. Though bark stripping by the deer was found, it was not evident that tree death by bark stripping enlarged the gaps. Regeneration was not completely absent in the gaps, although the number of regenerating stems was small. The regenerating species were limited to the originally abundant species, including Quercus glauca, Cleyera japonica, and Eurya japonica as well as species unpalatable to the deer, such as Symplocos prunifolia and Triadica sebifera, from the aspect of the floor layers．

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