The spread of forest fire is largely related to wind and topography. What is most important is the relationship between wind direction and topography in predicting the area of fire spread since the main direction of the fire spread is changes with the direction of the wind. This thesis analyzes the forest fire which occurred in Kakamigahara City in Gifu Prefecture in April 2002 as a major example. The idea of the analysis is that the land form classification map shows the distribution of the wind power in the area if the land form classification map for the eligible area is drawn up by using topographical elements considered to influence the wind. In other words, the flow of the wind can be recognized from the distribution map of the wind power, by which the area of the fire spread is predictable. The analysis in this thesis is based on this idea, and main topographical elements contributing to the fire spread of the forest fires provide a “form of topography,” namely, the topographical element representing steep or mild topography and “the topographical element representing direction where land is inclined.” In addition, the effect of the topography when the direction of the wind is changed (that is, the complex influence of wind direction and topography) is defined, and analysis is made based on it. As a result, it proved that the direction of the wind comprises a large element when predicting the area of fire spread, and it is important to predict in accordance with the change of direction of the wind in predicting the area of fire spread.

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It is said that forestry is affected by many complex factors such as geographic or the economic factors. So we must consider carefully when we study the activity of the total Non-Industrial Private Forest (NIPF) owners in Japan. We classified forestry regions in Japan according to the degree of activity of the NIPF owners to represent the activity of all NIPF owners. We propose a more useful method for classification using Principal Component Analysis (PCA) and the Ward method, which is one of the Cluster Analysis methods, together with the Self-Organizing Maps (SOM) algorithm. We validated this method and showed the results using actual data about the activity of the NIPF owners for classification of forestry regions. By applying the SOM algorithm, we could visualize and understand the results of classification more easily and intuitively. Moreover we could classify more accurately by having adopted not only the current state related to the activity of the NIPF owners but also the dynamic state as the variable. From the results of this analysis, we classified Japan into five forestry regions. We think the method can be applied to various regional classifications as long as the data collection is possible.

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Viewed from the erosion control in Hinoki cypress plantations, the dynamics of undergrowth was studied in order to apply the stand density control to vegetation control. Seventeen study plots were set to monitor long-term (10-to-13-year period) changes in coverage under common silvicultural ractices. Eleven plots were made to study the effects of heavy thinning on coverage 2 to 3 years after treatments. The coverage index was determined for each of the following 6 life forms with different light demand and performance in erosion control: commonest ferns (Gleichenia japonica and Dicranopteris linearis), light-demanding herbs and grasses, shade-tolerant herds (chamaephytes), evergreen trees, deciduous trees, and dwarf bamboos. The following 3 temperature zones were distinguished: zone without the commonest ferns and the evergreen trees, zone without the commonest ferns, and zone with both of the life forms. Another distinction was made regarding the type of vegetation according to the total coverage of the six life forms (C_T) as follows: poor vegetation type (C_T<40) and others (C_T≥40). In both the long-term study and the study on heavy thinning effect, the relationships between the change in yield index and the change in coverage index differed among life forms, temperature zones, and vegetation types. Based on the results, it was pointed out that accumulation of data on the relationship between yield index and coverage should be made with distinctions regarding the life form, the temperature zone, and the vegetation type in order to increase applicability of the stand density control to vegetation control.

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The migration of pinewood nematode, Bursaphelenchus xylophilus, inoculated on the top of 10-cm-long stem cuttings obtained from the current shoots of two types of Pinus thunbergii seedlings—a resistant family Namikata (t)-73 and a nonselected type—were investigated. Additionally, the number of cortical resin canals and the sectional area of each resin canal in each stem cutting were examined. The mean sectional area and the total area of the cortical resin canals were significantly larger in the nonselected seedlings than in Namikata (t)-73. Three days after the inoculation, more than half of the recovered nematodes were extracted from the uppermost part, within 2 cm from the inoculation point, of the stem cuttings of Namikata (t)-73. On the other hand, in the nonselected seedlings, approximately half of the recovered nematodes passed through the stem cuttings and the number of nematodes that passed through a stem cutting increased with the total sectional area of the cortical resin canals. These results suggest that the quantitative character of a cortical resin canal affects nematode migration in pine shoots, and that the total sectional area of cortical resin canals as an index of the quantitative character may represent the individual resistance level of P. thunbergii to pine wilt disease.

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An experiment on the natural drying of Chamaecyparis obtusa logging residue stems was carried out to determine the potential for use of this material as woody biomass (e.g. wood chip bio-fuel). The experimental residue logs, i.e., unused stems left after logging, were placed along a forest road at high altitude and on a paved landing at low altitude. At each site, half the material was naturally dried in the sun and the other half in the shade for about three months. Moisture content of the logs (MCL; dry basis) was almost constant at the forest road site, while it decreased from 82% to 38% within three months at the paved landing site. There was no significant difference between MCL dried in the sun and in the shade, whereas the MCL placed directly on the ground was about 10% higher than the MC of elevated logs. Average air temperature at the forest road site and at the paved site differed by 7 degrees (higher at the paved site) and average humidity was also 20% higher there. There was no significant effect of substrate type, i.e. soil vs. pavement, as determined by ANOVA. Thus, differences in air temperature and humidity between the sites were the main determinants in natural drying of logging residue stems.

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In this paper we constructed a volume table for broad-leaved trees including a stem and branches using a relative stem curve, provided that the trees are subject to the pipe model theory. First we measured diameters at every one meter length of stems and branches of 98 sample trees of Quercus acta and Castanopsis sieboldii in two stands in the Tokyo University Forest in Chiba, Japan, and calculated the square roots of the squared sum of diameters to fit relative stem curves. As a result, all of the relative stem curves fitted well to the samples, indicating that a relative stem curve could generally express the shape of broad-leaved trees including a stem and branches just as well as it has been employed to express the stem shape of coniferous trees. Finally a volume table was constructed using the average relative stem curve of 55 Quercus acta sample trees in the same stand, and the accuracy and precision of the table were examined against other sample trees compared with the table constructed by the conventional way of using the Yamamoto-Schumacher formula. The former gave less accuracy than the latter but gave almost the same precision.

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Studies indicate that training for forestry workers should combine on-the-job training (OJT) and step-by-step off-the-job trainig (OffJT). We are interested in designing a training system that constantly sets out skill levels in a step-by-step manner, and that is adapted to the workers' skill-acquiring processes. In this study, we conducted a questionnaire survey to elucidate forestry workers' current status concerning knowledge and skill training. Then, we classified their knowledge and skills into those acquired through OJT and OffJT, and clarified the processes by which they actually acquired knowledge and skills. The results showed that OffJT provided a basis for learning, and OJT taught practical and applied skills. It was apparent that workers learned in a progression from planting and caring work through to thinning and logging work over about three years. In addition, we considered the effect of the respondents' circumstances, and found a significant difference in the learning processes according to the number and variety of machines owned; we also designed training systems adapted to six different forestry situations.

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We surveyed the initial stage of a Platypus quercivorus infestation in a secondary forest dominated by Quercus serrata and Q. variabilis. Forty-three of 646 Q. serrata and 49 of 645 Q. variabilis trees were infested. The trees of both species were more severely infested at the ridge than on the slope. There was no entry hole found on trees smaller than 15 cm in diameter at breast height (DBH). Logistic regression showed that the percentage of infested trees increased with DBH, and also showed that Q. serrata was more infested than Q. variabilis. For both Q. serrata and Q. variabilis, the percentage of trees that exuded sap from their trunks was significantly greater in infested trees than in non-infested trees. In this study site, the mortality of infested trees might be lowered by discharge of sap. Forests with mature Q. serrata and Q. variabilis in the lowlands may play a role as refuge for P. quercivorus populations migrating from highland Q. crispula forests.

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We studied the fauna and the seasonal and diel activities of dung beetles that use the feces of the Japanese black bear (Ursus thibetanus japonicus) in Ashikawa, Yamanashi and Okutama, Tokyo. We recorded 18 species that are widely distributed and have been recorded in other mammal feces. Among these 18 species, the adults of 5 species were observed from spring to autumn, while the remaining 13 species were observed in a specific period. The proportions of the 10 species captured by bait traps confirmed that 5 species visited the feces diurnally and 4 species did so nocturnally. However, the diel visiting pattern of Onthophagus lenzii changed seasonally. We divided the 18 species into 2 functional groups: dwellers and tunnellers. Of these, 10 tunneller species were usually observed in the soil under or around feces and 8 dweller species were observed on or inside feces. The most common species, such as Onthophagus atripennis, O. ater, and Caccobius jessoensis, were tunnellers who visited the feces diurnally.

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The cypress bark moth, Epinotia granitalis (Butler), is a serious insect pest of the Japanese cedar, Cryptomeria japonica. Light traps have been used for monitoring the number of moths in forests. However, whether the number of moths captured by light traps reflects the number of moths emerged has not been examined yet. Since the last instar larvae of the moth leave feeding scars on the trunks, the number of scars was considered to be a good index of the number of moths emerged. To verify this assumption, I analyzed the correlation of the number of feeding scars on the trunks of 20 cedar trees in two different forests with the number of moths captured by the light trap placed in the same two forests for 6∼7 years. The results showed a strong positive correlation between the number of moths captured by the light trap and the number of feeding scars in both forests indicating that the number of moths captured by the light trap reflects the number of moths emerged. Thus, the light trap is a valuable tool to monitor the number of cypress bark moths emerged.

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Tree architecture represents various ecological and physiological functions, such as acquisition of light, spatial distribution of vegetative and reproductive organs and pathway for water and nutrients. In addition, tree architecture reflects characteristics associated with life history, survival and fitness of individuals within the community, such as acquisition of space, shade tolerance and reproductive output. Studies of tree architecture can link small-scale studies (e.g., physiology, morphology) and large-scale studies (e.g., forest community dynamics, ecosystem productivity). For example, analysis of tree architecture, which determines architectural hierarchy and also acts as hydraulic and photosynthate/nutrient pathways, will help integrate physiological measurements made at the leaf and shoot level to the whole-tree level. To elucidate forest community dynamics from dynamics of individual tree crowns, we must quantify, through analysis of tree architecture, concepts such as the “spatio-temporal dominance” of individuals within the community determined by their “potentialities”. In addition to conventional analyses of morphological modular units, such as shoots and branches, we must identify and analyze dynamics of functional modular units, such as shoot clusters, that function as physiological units and define crown growth and development.

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Knowledge of nitrogen mineralization in the soils of sugi (Cryptomeria japonica) stands is important for understanding the effects of forest management and environmental changes on nutrient cycling in the future. We summarized recent studies about nitrogen mineralization in the soils of sugi stands, and discussed directions of future studies. We first examined the methodology and associated problems for evaluating nitrogen mineralization, then investigated environmental factors and soil properties that control nitrogen mineralization in the soil. Rate of nitrogen mineralization, ratios of mineralized to total nitrogen and nitrified to mineralized nitrogen were calculated from published and unpublished data. These values were 93.7mg kg^-1 4 weeks^-1, 1.3% and 70% respectively. In the future, studies about nitrogen dynamics in the soil with tracer experiments under field conditions, and analyses of the relationship between direct uptake of organic nitrogen by tree roots and nutrition of fine roots will be required. We suggest that integrated studies about nutrient cycling for understanding the effects of environmental changes such as global warming and nitrogen saturation and forest management on nitrogen dynamics in the soils should be conducted.

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