We applied Buckingham-Darcy equation with measured soil K-θ relationship to the subsoil (90 cm depth) in the upper- and lower-plot of the forest slope, and calculated the vertical soil water flux throughout a year to validate the annual soil water flux and soil water flux during rainfall event. The annual soil water flux was 530 mm for the upper plot, smaller than the annual stream runoff rate of the study catchment (643 mm), and 982 mm for the lower plot, larger than the stream runoff rate. Both soil water fluxes were smaller than the annual precipitation of the study catchment (1,282 mm). We considered that these fluxes represented the difference of the slope position between the plots, and that they were reasonable as the vertical water flux in unsaturated soil below rooting zone. We could analyze soil water flux during rainfall event precisely using this method, and it was suggested that the lower plot’s soil, which was wetter than the upper plot’s, drain the infiltrated water larger than the upper plot’s.

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We investigated the reproductive process of evergreen understory shrub, Aucuba japonica var. borealis, from fruit ripening to seedling establishment and the effects of three biological interactions, in an oak Quercus serrata forest on the Japan Sea side, northeastern Japan, to evaluate the relative importance of pre-dispersal predation by gall-forming insects in the regeneration. A survey of all fruit in 0.25 ha plot revealed that galled fruit parasitized by the fruit gall midge Asphondylia aucubae occurred at 57% in a set produced in 1998 and at 77% in 1999. This pre-dispersal predation reduced heavily the seed production because about only 10∼20% of the galled fruits contained an intact seed. Mature intact fruits were almost completely consumed, and the seeds were dispersed for a short period from late April to early May by migrating Brown-eared Bulbul Hypsipetes amaurotis. We confirmed that wood mice ate the seed, but less than 10% of seeds sown at the site disappeared. Post-dispersal predation pressure by rodents may not have been heavy. The germination rate was about 80%, and the survival rate of one-year seedling was acceptable under good conditions. These results suggest that parasitism of fruit by gall former was the most important factor preventing seedling regeneration of A. japonica var. borealis at this site.

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In this study, a miniature seed orchard was developed in a closed glass room, in which homogeneous genotypes with male-sterile genes (aa) and heterozygous genotypes (Aa), respectively as seed parent and pollen parent, were arranged in lines. Efflorescence of male flowers of pollen parent (Aa) started on February 16th, which was 19 days prior to the natural pollen dispersal, following female flowers of seed parents (aa) which flowered on February 12th. Both reached a peak toward the end of the month. On the contrary, continuous pollen dispersal was not observed in the field until March 7th, with the pollen count peaking on March 21st, which lagged three weeks from the orchard. The germination rate of seeds from the orchard was 22.8%, which was close to that of the average for Cryptomeria japonica (15∼35%). Given that the seedlings then steadily grew and developed, favorably not so much different from those produced in existing orchards, and that the appearance ratio of male-sterile seedlings was 47.3% as anticipated, it was concluded that the orchard was effective in producing male-sterile seedlings.

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To examine appropriate seed transfer zones based on genetic differentiation of Alnus hirsuta, we investigated chloroplast DNA haplotypes at 13 natural forest sites, 5 commercial slope afforestation sites, and 4 commercial forest protection sites in Toyama Prefecture, Japan. The haplotypes of Alnus hirsuta in the natural forest were classified into two types: those in high-altitude areas at 1,100 m or higher (Type I), and those in areas below this altitude (Type II). The haplotypes of trees used in slope afforestation and forest protection were all Type II, regardless of altitude. Because Alnus hirsuta is wind pollinated and sets flowers several years after planting, there is a high risk of genetic disturbance by hybridization in high-altitude areas where seedlings of different halpotypes are planted. In afforestation industries, therefore, it will be necessary to take account of the haplotypes. With the aim of achieving stable production of Alnus hirsuta in local planting stocks, we examined the seed yield at high altitude in the natural forest. Our results showed that year-to-year variations were extremely large, making it difficult to harvest a stable level of seeds every year. However, because the seeds are highly preservable, it should be possible to cope with this problem by setting up seed-production stands based on analysis of the chloroplast DNA, and then harvesting a large amount of seeds in high-yield years and storing them until the next high-yield year, in order to ensure stable production of Alnus hirsuta in local planting stocks.

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The relationships between browsing damage by sika deer (Cervus nippon yesoensis) on trees in young plantations and relative deer density indices, including the average and median results of spotlight surveys for each deer management unit and sightings per unit effort (SPUE), were examined based on data from the “Survey on impact of sika deer browsing on forests” conducted by the Hokkaido Government in 2006. Generalized linear model analyses indicated that there were significant relationships between the occurrences of leader shoot browsing, both in each stand and for each tree, and the relative deer density indices in each management unit for each of the broad-leaved trees, larches, and evergreen conifers. The occurrence of browsing on broad-leaved trees in units with low deer density can be recognized as a sign of an increase of deer in the area. However, browsing will not be recognized as forest damage until the deer density increases to exceedingly high levels because the percentage of browsed trees was high only at such densities. The relationship between the occurrence of browsing and relative deer density indices suggests that the prediction of deer browsing damage is possible based on browsing in young plantations as well as relative deer density indices.

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Long-term changes in the water quality of soil water and streamwater were monitored before and after cutting at the lower slope position in a small forested watershed composed of artificial stands of old aged Japanese cedar and cypress in the northern Kanto region in Japan. The NO₃⁻ concentration in soil water directly reflected the N dynamics, i.e., the reduced nutrient uptake and accelerated nitrogen mineralization in the surface soil layer immediately after the cutting, and the increased nutrient uptake induced by regenerated trees several years after the practice. In contrast, the NO₃⁻ concentration in streamwater maintained higher level than before cutting in the sixth year after the practice. The NO₃⁻ concentrations in high and low discharge, which is dominated by direct flow and base flow, respectively, were calculated from the relationships between discharge rates and the NO₃⁻ concentration in streamwater. The results suggested that the NO₃⁻ distribution in soil affects the NO₃⁻ concentration in streamwater. Changes in the NO₃⁻ concentration in the subsoil were calculated using the HYDRUS-1D model, and these changes were consistent with previously measured seasonal and long-term changes in the NO₃⁻ concentration in streamwater. This finding implies that NO₃⁻ adsorption characteristics of the volcanic ash subsoil affects NO₃⁻ leaching into streamwater. In order to clarify the effects of the aging of artificial forests, the method of cutting, and environmental changes on N dynamics in soil and streamwater, it is necessary to consider the NO₃⁻ adsorption characteristics of volcanic ash soil.

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We analyzed the influence of drying condition on drying speed (arrival day of moisture content 50% or decline trend of moisture content) under the condition that character of logs (height above ground, log length) or drying methods (days of drying, paved or unpaved, using or not using of crossbeam, presence or absence of roof) to develop efficient dry method of Japanese cypress and Japanese cedar for woody biomass boiler. The days required to reach 50% moisture content were that in case of Japanese cypress of 80% initial moisture content were 83∼151 days and in case of Japanese cedar of 130% initial moisture content were 93∼187 days. The drying rate of cypress were faster in order 1m log with roof and crossbeam, 1 m log on paved area and 2 m log on paved area. In case of cedars the drying rate were faster in order 2 m logs with crossbeams on paved area, 2 m logs with crossbeam on ground, 2 m logs on paved area, 2 m logs on ground. About paved and unpaved, drying speed of paved area was faster than unpaved area. The drying speed was faster in the case of using crossbeams and paved area. Drying speed in case of using crossbeams on unpaved place was as fast as that of using crossbeams on paved place.

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Armillaria tabescens is one of the most serious root rot pathogens affecting ornamental trees in Japan. To investigate the distribution of A. tabescens in the soil, experiments using the bait method were conducted in a Cerasus × parvifolia ‘Fuyu-zakura’stand. A total of 615 oak logs were placed in 11 experimental plots in the damaged stand, which included infected and dead ‘Fuyu-zakura’ trees. Rhizomorphs and/or mycelial fans of Armillaria spp. were detected in 86 of the oak logs. All 58 isolates originating from the 86 oak logs were identified as A. gallica by mating test and PCR-RFLP analysis. A. tabescens was not detected by the bait method. It was concluded that A. gallica is distributed widely in the soil.

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We analyzed the spatial distributions of Platypus quercivorus attacks on trunk surface lower than 1.5 m above the ground level of six Quercus crispula trees, which were newly infested and killed in the season. The density of the entry holes (attack density) on the census occasion when insect attacks were first observed on respective trees, early attacks, was 27.1 m⁻², and the total attack density was 173.0 m⁻², on average. The percentage of the early attacks was 16.2%. The early attack density was correlated negatively with the heights above the ground level, and tended to be higher on the downhill-facing half than on the uphill-facing half of trunk surface of investigated trees. A similar tendency was also found in the total attack density. These results suggests that the attacks of Platypus quercivorus can be controlled by intensive treatment on tree trunks on down-hill facing surface near root collar, on which attack density will be higher than any other parts of trunks.

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The forest management regime of Alberta, Canada, was reviewed in light of the three pillars of sustainable forest management: economic, social, and environmental values of forests. It was found that as long as the provincial policy is inclined to the pursuit of economic benefits derived from the short-term resource development in the boreal forests, it would be difficult to either maintain or enhance the social and environmental values of the forests at the same time. The boreal forests provide resources for timber production, oil and gas development, and a quality of life for forest-dependent community members including Aboriginal peoples. This leads to the need for integrated resource management (IRM) through public participation, which takes into consideration all stakeholders’ benefits in the region and ecosystem protection. In addition, a comparison was made between zoning and the management regime based on the principles of Forest Stewardship Council (FSC), both of which are applications of IRM. As a result, differences were found in terms of achieving a balance between the three forest values. It was also found that planning IRM needs transparent and participatory decision-making processes, which enables all stakeholders not only to claim their benefits, but also to discuss how to achieve a balance between three forest values.

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