The demand for raw bamboo materials become sluggish in recent years, consequently, the untouched bamboo forests keep increasing in Japan, which make the sustainable use of bamboo resources becoming an important issue. In order to consider the future revitalization of bamboo industry in Japan, we conducted fundamental research by means of questionnaire survey to investigate enterprises that are processing and selling bamboo products in Kagoshima Prefecture. One Survey conducted in September 2018, on total 45 enterprises, collection rate 64.4％. The questionnaire covered the current operation state of company, bamboo resources utilization and products distribution. We examined the changes and regional characteristics of bamboo industry. The results indicated that 1) The number of enterprises especially the traditional craft-enterprises decreased significantly from 1974 to 2018, the aging of craftsman and increasing of import may the main causes, 2) The item composition of bamboo products has also changed, 3) Many enterprises sustain through newly designed products and cultivation of sales channels. It is considered that the number of traditional enterprises may keep decreasing in the future. For the preservation of bamboo industry in Kagoshima, consequently, it is necessary to securing the bamboo forest which can produce high quality bamboo and Inheriting traditional bamboo products processing technology or wisdom. It also considered important to understand the trends of productions and distribution of bamboo products in China.

Generally, housing structures in Okinawa Prefecture are reinforced concrete structures, but wooden structures, which are common in Japan, are rarely constructed. However, a previous study reported that there was a movement to export pre-cut lumber for housing construction in Okinawa from 1990s onward. The proportion of wooden structures in housing starts had increased mainly in detached homes, and after two pre-cut factories were established in the special economic zone of Okinawa in 2015-2016, it increased further. This study was conducted to clarify the relationship between two pre-cut factories and increased demand for wooden structures in Okinawa through an interview survey of business managers. Both factories had the purpose to respond to the growing demand in Okinawa and reduce distributional disadvantage, but only one factory was involved in exports used the promotion measures. Whether to export affected the selection of materials and the location of the factory. Both factories primarily used kiln-dried wood and/or laminated timber to supply strong and high-quality wooden houses as typhoon and earthquake countermeasures. Unfortunately, the production capacity of each factory was restricted due to the shortage of labor. Moreover, the purchase demand for the heat utilization of woody biomass in Okinawa was not sufficient to justify the processing cost of industrial waste, such as sawdust.

Japanese oak wilt disease is caused by fungi, which are brought by Platypus quercivorus into the trunk, hinder water supply by filling vessels with its hyphae and then weaken/kill trees. To evaluate the regeneration of Quercus phillyraeoides stands damaged by Japanese oak wilt disease by cutting survived trees, we investigated the effects of infection and gallery formation by P. quercivorus on sprouting success of Q. phillyraeoides. We investigated gallery density and the proportion of xylem discoloration of stumps, and evaluated the sprouting success 1 year and more than 5 years after cutting in two stands in Wakayama Prefecture, Japan. Although there were no significant effects of gallery formation on individual-level mortality rates both 1 or more than 5 years after cutting, the individual-level mortality rate more than 5 years after cutting was larger than that 1 year after cutting. Moreover, there were no significant effects of gallery formation on number and size of sprouts both 1 or more than 5 years after cutting. The number of sprouts 1 year after cutting decreased as increasing in the gallery density. However, gallery density and the ratio of xylem discoloration were positively correlated with stump diameter, which is known to be one of the factors decreasing the sprouting success of Q. phillyraeoides. Therefore, we were not be able to quantify the net effect of the gallery formation on sprouting success of Q. phillyraeoides. In summary, cutting of survived trees of Q. phillyraeoides after attacks of P. quercivorus contributes to regeneration of the stand by sprouting, because most individuals can survive and generate sprouts.

This study aims to comprehend the association between visual stem indicators in natural forest management under the selection system by employing Bayesian network analysis. A tree-marking exercise was conducted at a research plot comprising 184 trees with natural forest management at the University of Tokyo Hokkaido forest, located in northern Japan. We constructed the Bayesian network model for seven learning models (model1 - model7), with two retrieval algorithms, such as HC (pattern1 - patten3) and SA (learning iteration＝1,000, 10,000 and 100,000). Performance evaluation of the proposed model was performed with the help of Matthews correlation coefficient (MCC) index. Verification for classification accuracy for unknown data was performed with m-fold cross-validation method. The most classification accuracy without cross-validation model indicated that MCC was 0.87, which was a SA model (learning iterations＝10,000 and 100,000). That of with cross-validation model indicated that MCC was 0.44, which was a HC model (model1, pattern2). As for the association between visual stem indicators, number of parent nodes was three visual indicators for HC model and five visual indicators for SA model. Two visual indicators as parent nodes were common to two retrieval models.

In Japan, the forest agency attempted to make forest gaps, using forest-thinning, to form a foraging habitat for Golden eagle. The attempt is not considered characteristics of foraging habitat of Golden eagle because of lack of information about that. In order to evaluate characteristics of foraging habitat of Golden eagle, we identified the foraging habitat of Golden eagle within the habitat of one pair in Niigata prefecture, and measured size and shape of that. During the winter and summer, foraging habitat of Golden eagle was forest gap. And forest gaps within study area are presumed to be foraged by Golden eagle, regardless of its size and shape. Although snowy field and open forest widely distributed within study area, Golden eagle would not forage frequently at that habitat. It will be necessary to evaluate the utilization frequency of snowy field and open forest in detail.

Genetic diversity of Toxicodendron vernicifluum trees planted in Japan was evaluated using two types of simple sequence repeat (SSR) markers: expressed sequenced tag (EST)-SSRs and genomic SSRs. ESTs were isolated from two T. vernicifluum clones using next-generation sequencing. Twenty-one primer pairs were designed to amplify ESTs with an SSR region, which is a 2-3 bp repeat motif, and eight EST-SSR markers were developed. These eight EST-SSR markers and seven genomic SSR markers were used to characterize genetic diversity and genetic structure among nine stands of T. vernicifluum planted in Japan. This species was introduced into Japan from wild populations in ancient times. It is easy to clone this species using root cuttings, and the loss of genetic diversity within the T. vernicifluum stands had become a concern. However, some analyses indicated that most of the stands in Japan retained genetic diversity, slightly higher than that of T. succedaneum, a closely related species. Moreover, genetic structure among stands was caused by transfer of seedlings. The risk of genetic bottleneck, resulting in reduced genetic diversity among the T. vernicifluum stands planted in Japan, is low. If the T. vernicifluum trees stands in Japan are suitably managed at present, this valuable genetic resource may not be at risk for extinction.

Anatomical features of the inner bark of three clones of urushi trees (Toxicodendron vernicifluum) with different amounts of lacquer production were investigated with light microscopy and cryo-scanning electron microscopy. All of trees showed a similar structure of inner bark. They formed longitudinal resin canals and traumatic resin canals close the cambium in the inner bark. Cryo-scanning electron microscopic images showed that all of longitudinal resin canals and traumatic resin canals were filled with resin. Trees of clone with higher amounts of lacquer production formed wider inner bark, higher number of resin canals and larger cross-sectional area of resin canals than those with lower amounts of lacquer production. In addition, trees of clone with higher amounts of lacquer production formed more traumatic resin canals close to the cambium than those with lower amounts of lacquer production. Our observations suggest that the structure of inner bark, in particular the quantity and size of resin canals, might be suitable anatomical index for the clonal selection of trees that produce higher amounts of lacquer.

Increased supply of lacquer materials is required with a surge in lacquer demands for restoration of national treasures and important cultural properties in Japan. To increase their production, much more lacquer trees (Toxicodendron vernicifluum) must be planted on their suitable plantation sites urgently. In this study, relationships between soil physico-chemical characteristics and growth properties were verified based on the survey data at eight plantations with either rich or poor tree growth, in four prefectures of Japan. Soils of rich growth lands had higher values of cation exchangeable capacities, thicker effective soil layers, and higher contents of soil porosities than those of the poor ones. Moreover, soil profiles with rich growth were generally equivalent to the features of “Moderately moist” soils in “Classification of Forest Soils in Japan (1975)”. Inversely, those with poor growth had the features of “Gley soils” or “Peaty soils”, which are generally poorly drainable soils. Those results were corresponded with the soil characteristics of suitable sites for planting lacquer trees which had already been reported by many previous projects of its planting. Relationships between soil pH, textures, and growth properties were not clarified in the present study unlike the reports of previous projects. Because poor growth plantations had the land use histories such as paddy fields without some drainage facilities and grassland with flat topography on the bottom of slope where natural water gathers, it should be strongly paid attention with their land history and topographical characteristics capable of forming high humidity soil conditions when planting the lacquer trees.

Increasing the demand of the lacquer, the plantations of lacquer tree have been developed in Japan. However, many of them are currently declined because of unknown factors. To clarify the cause of the decline, we attempted to detect the pathogens from the plantation soils. Consequently, Phytophthora cinnamomi, a well-known root-rot pathogen, was detected in almost all plantations excepting Hokkaido and Iwate Prefecture. Inoculation test by soil infestation revealed that the inoculated trees were declined within 3 months. Thus, Phytophthora cinnamomi can be a threat for the lacquer tree plantations in Japan. This is the first report of P. cinnamomi root rot disease of Toxicodendron vernicifluum.

We have investigated the effects of tree density and Diaporthe canker disease on the growth of sprouts of lacquer trees, Toxicodendron vernicifluum. We set up four density treatments: 1,600 trees/ha, 3,000 trees/ha, 6,000 trees/ha, and no treatment at a location where the trees had been clear-cut. We then investigated sprout height, stem basal diameter, and canker disease occurrence after two years. An analysis of variance indicated significant differences in stem basal diameter, with greatest diameters in the lowest density treatment. We found canker disease caused by Diaporthe toxicodendri and observed three main symptoms: blight, sprouting from a girdling canker, and sunken canker. The disease was found in 49.6％ of the 131 sprouts examined. We concluded that the stem basal diameters were widest in the 1,600 trees/ha treatment both because of the low tree density and because the ratio of sprouting from a girdling canker was low. These results indicate that stem basal diameter growth can be optimized by removing the diseased trees in areas affected by canker disease and maintaining trees at a density of 1,600 trees/ha.

Based on interviews with owners of the lacquer trees, Toxicodendron vernicifluum (Urushi) in the northern region of Iwate Prefecture, this study aims to clarify how to select crops and to clarify profitability when planting lacquer trees. As a result, it was revealed that the lacquer trees were often planted on sites such as millet, tobacco, and fruit trees were planted before. The trees are superior in that they can earn revenue with less labor compared to the T. vernicifluum and those crops. When comparing the lacquer trees and the Japanese cedar, planters chose the lacquer tree because it was superior in shorter period until earnings. Regarding current profitability, it became clear that high profitability can be realized when the number of weeding times is small.