In order to convert the stand wood volume into the merchantable stand volume, the merchantable ratios at culm- and stand-levels were determined for one of the most famous bamboos, Phyllostachys pubescens Mazel ex Houz. First, the merchantable ratio at culm level for each merchantable diameter was determined using the data of 200 felled culms. As the diameter at breast height increased and the merchantable diameter decreased, the merchantable ratio became higher. The combination of the determined ratio and the one-way volume table constructed in a previous study enabled us to develop a one-way merchantable volume table for P. pubescens. Second, the merchantable ratio at stand level was determined based on the ratio at culm level using the data collected from 30 plots. The merchantable ratio at stand level became higher as the merchantable diameter decreased. The result also suggested that we should pay an attention into the change in the ratio at stand level with the mean diameter at breast height. The determined merchantable ratios will be effective when converting the stand wood volume into the merchantable stand volume for P. pubescens.

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Recovery of dwarf bamboo (Sasamorpha borealis) and regeneration of tree species were investigated inside and outside two deer-proof fences in a beech forest diminished by sika deer. One fence was installed in 1997 (1997F) and the other was installed next to it in 2002 (2002F). The time lag in installing the deer-proof fences was evaluated from the data 7 years after the installation of the fences. The height of the S. borealis protected by 1997F was equal to that protected by 2002F. Coverage of S. borealis inside 1997F grew wider with progress of time, but that inside 2002F did not increase. Floor vegetation inside 1997F consisted of S. borealis (21%), trees (18%), and shrubs (35%) in relative dominance, while that inside 2002F consisted solely of shrubs (82%). The density of regenerated trees higher than S. borealis was 1,250/ha in both 1997F and 2002F. These findings demonstrated that the early establishment of deer-proof fences enables the best possible recovery of S. borealis. In contrast, our evaluation suggested that early establishment of deer-proof fences is not necessary for the regeneration of tall trees. Further monitoring is required to predict the future regeneration of trees.

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We analyzed the use of honey source plants in apiculture in Hokkaido, northern Japan, based on the “Annual Report of Honey Source Research” published by the Hokkaido Association of Apiculture. Black locust, basswood, clover, Amur corktree, thistle, buckwheat, and horse chestnut were reported as the seven primary honey source plants in Hokkaido. Tree species accounted for approximately 70% of the total honey production among the seven plants, and nearly 80% was explained by adding thistle, one of the forest understory plants. This indicates that forests play an important role as honey sources. Cluster analysis divided Hokkaido into five geographic regions based on the composition of honey source plants in each region (sub-prefecture) : Pacific region, Okhotsk region, Northern Hokkaido, Central Hokkaido, and Southern Hokkaido. For basswood and Amur corktree in particular, tree biomass in each region was exponentially correlated with the number of beehives that targeted each tree species. Regional diversity in the seven primary honey source plants was also correlated with the cumulative number of beehives, implying that high productivity can be achieved by having a high diversity of honey source plants.

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We developed a distributed runoff model that utilizes a contour-based topographic approximation (TOPOTUBE). The model consists of logical algorithms for water flux and associated routing for Hortonian overland flow, saturation overland flow, and saturated soil matrix flow. The model was applied in a 4.9 ha watershed covered by Japanese cypress forest in Mie Prefecture, central Japan. Changes in infiltration capacity with respect to rainfall intensity and soil water repellency were considered. Because spatial variability of infiltration capacity affects the occurrence and transport of overland flow, we employed detailed field information of soil infiltration capacity based on ground cover distribution. Agreement between observed and estimated catchment storm runoff improved when these spatial patterns of infiltration were considered in the model. In addition to these spatial patterns, further internal spatial variability of infiltration capacity based on the standard deviation of estimated infiltration capacity was included. This assumption means that locally high infiltration pixels are randomly distributed within the hillslopes. Observed and estimated overland flow generation at the hillslope plot scale showed that associating such internal variability of infiltration capacity can further improve the simulation of overland flow generation.

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A tornado occurred on May 6, 2012 from Jyoso city to Tsukuba city in Ibaraki Prefecture. The tornado severely destroyed forests in some areas. We analyzed 5 damaged forests of the Yamaki and Hirasawa districts in Tsukuba city to clarify the characteristics of the damage due to the tornado. A circular damaged area with about 300 m of diameter was observed at the end of the path of the tornado. Except for the area, we recognized some characteristics of damage; (1) The severely destroyed areas occurred in a belt of about 100 m of width. (2) Almost all trees were damaged in the path of the tornado even though they were broad leaf trees or had low height-to-diameter ratio, the types of trees that would be expected to have strength in strong wind. (3) The damaged trees were usually fallen to the direction of the center of the tornado path showing the convergent wind caused by the tornado.

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To clarify the effect of forest thinning on evapotranspiration, thinning was conducted within a basin (HV, 0.88 ha) with planted hinoki (Chamaecyparis obtusa) and sugi (Cryptomeria japonica). This basin lies within the Hitachi Ohta Experimental Watershed, in the northern part of Ibaraki Prefecture, Japan. Thinning was 50% of trees and 30% of timber volume. Daily evapotranspiration for HV and calibration basin HA (0.84 ha, same vegetation) was estimated using the short-period water budget method. The regression curve between HV and HA for daily evapotranspiration before thinning was determined. Daily evapotranspiration in HV when thinning was assumed to have not been done was estimated from the regression curve based on daily evaporation in HA. The change of evapotranspiration after the thinning was shown by the difference between the actual measurement value and estimated value in HV, using the paired catchment experiment. Evapotranspiration estimated by atmospheric conditions was estimated by the Priestley-Taylor equation and used as a rough standard of daily evapotranspiration. Our results show that yearly evapotranspiration reduced about 17% after thinning. The effect of thinning on evapotranspiration appeared gradually after six months, and was more pronounced after two years. Additionally, the effect was strong from June to October.

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To estimate the acorn crops as the food resource of Japanese black bear (Ursus thibetanus), I examined the relationship between the production of sound (mature) acorns and the number of fallen male inflorescences of three Fagaceae species (F. crenata, Q. crispula, and Q. serrata). The annual fluctuation of male inflorescences in F. crenata tended to synchronize strongly with that of the total or sound acorns, and the regression equation between the number of male inflorescences and sound acorns showed a high coefficient of determination. On the other hand, the annual fluctuation of male inflorescences and mature acorns in two Q. species did not synchronize as strongly as that in F. crenata, and the regression equation between the number of male inflorescences and mature acorns in both species showed a low coefficient of determination. However, the acorn crop size estimated by the predicted number of sound (mature) acorn substantially matched up to the results based on the monitoring survey of fruiting intensity of three species in each year. These results showed that grasping the number of fallen male inflorescences is effective to provide a rough tendency of acorn crops in three Fagaceae species in early summer.

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A method for predicting beech seeding based on fallen male inflorescence number was evaluated in Hokuriku district, Japan. Flowering and seeding was investigated for 7∼13 years at five stands in disjunct populations and nine stands in continuously distributed populations. It was demonstrated that female flower production can be estimated from fallen male inflorescence number from May to June. Also, it was possible to predict the proportion of filled seeds using estimates of female flower production in the current and previous year. However, Hokuriku district differed from Hokkaido and Tohoku districts in the minimum value of female flower production for mast seeding. In the disjunct populations, the proportions of empty and immature seeds were high, as a result of pollen limitation owing to reduced population size and/or low genetic diversity. Therefore, it is suggested that an equation for estimating the proportion of filled seeds should be formulated for each area and in each population classified by continuity of distribution. The effectiveness of the prediction method was verified by the approximate correspondence between the crops estimated from fallen male inflorescence number and the actual crops. This method is suitable for predicting seed crops until early summer and, for example, may be useful for assessing whether seeds can be collected in autumn.

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A simple method for evaluating the acorn yield of Quercus serrata was developed and tested. This simple method of evaluation, classified the yield qualitatively according to descriptive criteria assessed by direct observation of the tree canopy. A quantitative standard was also established to determine whether trees had fruited, and, if so, to estimate whether the crop yield would be above or below average. The fruiting of 392 Q. serrata trees were examined simultaneously in two ways: (A) by several unskilled observers using the simple evaluation method, and (B) by a forest researcher employing the established method based on the average number of acorns on the terminal 50 cm region of the branches. The results obtained using these two methods (which were summarized into 3 levels) were in agreement for 75% of the trees, when the data from individual observers using method (A) were compared with method (B), although the simple evaluation method (A) had a tendency for underestimation. However, when the largest value from the multiple observers was used, the concordance rate with (B) improved to 86% and the evaluation bias was also eliminated. The results of the study indicate that the newly developed, simple evaluation method, when used by several unskilled investigators simultaneously, produces a reliable assessment of the acorn yield and is suitable for monitoring acorn crops in practice.

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For the purpose of predicting the infest of the Asiatic black bear, Ishikawa Prefectural Government conducted the survey for the prospective yield of the masts of the three Fagaceae species. The survey has been entrusted to the Ishikawa Nature Guide Association, which is a volunteers association for guide service of nature. As a result of questionnaire, most of the members who participated in the investigation answered that they were able to get a greater understanding about the relation between beechnut production and bear infest. And it became clear that this experience was also helpful to improve their normal activities of nature interpretation. Thus, to involve nature guides in such investigation activities is considered to contribute to promote the proper knowledge of bear infest issue to the public secondarily. In addition, when it entrusts a volunteer group, it is important to adopt not only the technical methods to conduct easily the investigation and open the workshop for investigations, but also to choose the investigation sites with an expert.

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The annual fluctuation of flowering and seeding of Fagus crenata was estimated from female inflorescence scars and flower buds in five stands in Toyama Prefecture, Japan. Various patterns of annual fluctuation of flowering were observed at branch level and it was considered that the internal resource dynamics might be related. The estimated seed crop at stand level showed good correspondence with measurement by seed traps. Beechnut production is suggested to be related to the degree of intrusion into residential areas by Asiatic black bears in Toyama Prefecture because the number of culled nuisance bears tends to be low in high-seeding years. The extremely low number of culled bears in mast seeding years was probably related to the preference of bears for beechnut. Poor seeding years were not consistently years of heavy bear intrusion, thus the seed production of other species, for example Quercus crispula, is inferred to relate to heavy bear intrusion.

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The relationship between the acorn crops of trees belonging to the Fagaceae family and the mass intrusion of Asiatic black bears (Ursus thibetanus) into the residential areas of the Hokuriku region were investigated based on an acorn crop monitoring survey conducted over a 7-year period, from 2005 to 2011, in the Toyama, Ishikawa, and Fukui Prefectures of Japan. Large fluctuations were observed in the annual acorn production of both Fagus crenata and Quercus crispula located in the high-altitude areas of all three prefectures. In particular, extremely poor yields of acorns were noted for 2006 and 2010, which coincided with the mass intrusion of bears into the residential areas. In contrast, little fluctuation was observed in the annual acorn production of Q. serrata distributed in low-altitude areas, and there were no incidents of years with extremely poor yields. These results infer that food shortages, due to simultaneous poor crops of F. crenata and Q. crispula in the mountainous areas of Hokuriku region, triggered the mass intrusions of bears into residential areas. Since the fluctuations in the annual acorn production of these key species were synchronized across a wide geographic area, a comparative analysis and coordinated survey of the acorn crop monitoring of each neighboring prefecture should result in an effective as well as accurate forecast of the acorn yields and therefore of bear intrusions.

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