Journal of the Japanese Forest Society
Online ISSN : 1882-398X
Print ISSN : 1349-8509
ISSN-L : 1349-8509
Volume 97, Issue 1
Displaying 1-12 of 12 articles from this issue
Articles
  • Haruka Suzuki, Takuro Mori
    2015 Volume 97 Issue 1 Pages 1-9
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Supplementary material
    This study discusses the characteristics of timber demand and the manner in which it is determined, to provide information to facilitate the preservation of traditional wooden houses, based on a case study of the Kaya Important Preservation District for Groups of Traditional Buildings in Yosano town, Kyoto, Japan. We analyzed 1) the process and work schedule for house repairs and landscaping as part of the public project, 2) the house owners' reasons for the house repairs, and 3) the work elements of house repairs and landscaping. In addition, we inspected various official documents and interviewed the officers and workers involved in the house repairs. We identified the three main types of timber in demand. The first type comprised the Cryptomeria japonica boards for walls. The second type comprised the Cryptomeria japonica, Pinus densiflora, and Chamaecyparis obtuse boards and square timbers for roofs. The third type comprised the Chamaecyparis obtusa and Cryptomeria japonica boards for wooden fittings. The timber demand increased because the district was officially designated as an Important Preservation District, and households could avail government assistance toward the repair costs. Each building's work amount was limited by factors related to administrative procedures and was affected by the halting of work during snowy periods. Many house owners repaired their main buildings first and hoped to conserve their landscape. The future challenge is to determine the quality and species of the timber used for the repairs, as well as to incorporate structural works into the public program for house repair.
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  • Takayuki Ota, Hisashi Sugita, Tatsuo Kanazashi, Takashi Masaki
    2015 Volume 97 Issue 1 Pages 10-18
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    We compared the density and survival rate of current year seedlings of Cryptomeria japonica between 2 types of substrates (stumps and ground surface) in a natural C. japonica forest in Akita Prefecture to clarify the process of establishment of seedlings. Seedlings emerged biyearly during the study period. The survival rate of seedlings was higher on stumps than on the ground. The survival rate of seedlings that emerged on the ground in 1994 was 0.2%, whereas that of seedlings on stumps was 21% in 1997. At 6 years after seedling emergence, all the seedlings that had established on the ground died whereas those that established on stumps survived. Because of the higher survival rate, total number of seedlings on stumps was greater than on the ground during 3 to 6 year after emergence. No significant correlation was observed between stump height and survival rate of seedlings. However, significant correlation was observed between emergence height of seedlings on stumps and their survival rate. Higher positions of stumps appeared to be associated with higher survival rate because of earlier exposure to light in the spring in our research plot which was situated in an area that experiences heavy snow fall. Thus, it should be concluded that aggregation of C. japonica on stumps was caused by higher survival rate, not by the high density of emergent seedlings.
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  • Takashi Nagashima, Megumi K. Kimura, Yoshihiko Tsumura, Kosuke Homma, ...
    2015 Volume 97 Issue 1 Pages 19-24
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Supplementary material
    To determine the effect of disturbance on clonal structures of natural forest of Cryptomeria japonica, we have investigated spatial distribution and size structure of this species in two forests. We have set up two plots, the first one is disturbed by typhoon while another one is not affected by typhoon disturbance, and investigated the clonal structure using SSR markers. We found three types of clonal structure: (a) gathered and middle size ramets, (b) apart and different size ramets, and (c) many small ramets in line. The (a) and (b) are thought to be layering clones from withdrawn juvenile or bud by heavy snow pressure. The (c) were buds from an uprooted individual by typhoon disturbance. The result suggests that typhoon disturbance and snow pressure are one of the factors to form different clonal structures.
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Short Communication
  • Yuuki Sano, Masato Shibuya
    2015 Volume 97 Issue 1 Pages 25-29
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    We conducted a thinning experiment in secondary Betula ermanii stands on scarified sites and examined the thinning effect on stand and tree growths after the thinning. The experiment was conducted in natural B. ermanii stands in the Uryu experimental forest of Hokkaido University, and 3 plots thinned to approximately 1,000, 2,500, 5,000 trees/ha and an unthinned, control plot were established at 16-year-old stand age. After 20 years of the thinning, mean diameter at breast height was 8.4-13.1 cm and larger in the order of thinning intensity, and therefore, thinning effect was recognized in the thinning experiment. In 1000-tree-plot, tree growth was apparently accelerated in 12 years after thinning, and thereafter, tree competition was enhanced. In 2500- and 5000-tree-plots, the relative yield indices were more than 0.9 at 12 years after thinnings, and they were considerably crowded. Relationships between mean diameter increment and tree diameter differed among plots after the thinning, but the differences diminished with tree growth. In conclusion, we recommend an intensive thinning in natural B. ermanii stands in young growth stage, because tree growth would be enhanced and thinning cost would be small in such a thinning system.
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Special Issure " Radioactive Contamination in the Forest due to the Fukushima Daiichi Nuclear Power Plant Accident "
Preface
Articles
  • Species-related Transfer Processes of Radiocesium from Tree Crowns to Ground Floor during the First Two Years
    Takuya Kajimoto, Satoshi Saito, Tatsuro Kawasaki, Daisuke Kabeya, Keni ...
    2015 Volume 97 Issue 1 Pages 33-43
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    We examined the dynamics of radiocesium in the forest ecosystems which were contaminated by the Fukushima Daiichi Nuclear Power Plant Accident. Field measurement and sampling were conducted in eight stands; plantations of Japanese cedar (Cryptomeria japonica, n = 4), Hinoki cypress (Chamaecyparis obtusa, n = 2), Japanese red pine (Pinus densiflora, n =1), and deciduous broad-leaved forest dominated by oak (Quercus serrata, n = 1). In each stand, 137Cs deposition in trees was estimated separately for each aboveground component (leaves, branches, and stems) using the data of specific 137Cs activities and biomass of these components obtained during 2011-2013. We found that tree-137Cs decreased substantially during the period for all forest types. In 2013, however, the 137Cs ratio of trees to stand total (i.e., trees plus litter and soil) differed by forest type: Japanese cedar (6-24%) and Hinoki cypress (10-12%) were higher than pine (2%) and deciduous broad-leaved (3%) forests. The results suggested that the early 2-year transfer process of radiocesium from the tree crown to the ground differed depending on the amount of initial 137Cs deposition and differences in leaf longevity and biomass of dominant species.
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  • Mitsutoshi Umemura, Tsutomu Kanasashi, Yuki Sugiura, Chisato Takenaka
    2015 Volume 97 Issue 1 Pages 44-50
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    To clarify the distribution of radiocesium (137Cs) in a Moso bamboo (Phyllostachys pubescens) forest in Fukushima Prefecture after the Fukushima Daiichi Nuclear Power Plant Accident, we visually and quantitatively investigated 137Cs contamination levels in each organ of the bamboos, which sprouted before 2010 and after 2011, in 2012 and 2014. From the analysis on the bamboo samples taken in 2012, the highest 137Cs concentration was found in the node parts of both the culms and branches in the before-2010 bamboo due to the direct fallout containing 137Cs. This fact suggests a long-term contamination with little leaching of 137Cs in the bamboo forest. From similar 137Cs concentrations in each organ among the different-aged bamboos, it was supposed that 137Cs diffused from before-2010 bamboo to the 2011-sprouted bamboo just after the accident and also that the root uptake of 137Cs might contribute to the contamination in the 2011-sprouted bamboo. However, we did not find the evidence of root uptake in 2014 from the results of 137Cs distribution in the root system. These results suggested that 137Cs absorbed just after the accident has been diffusing throughout the bamboo forest via the rhizome system.
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  • Cases of Forests in Minamisoma in 2012 and 2013
    Masaya Masumori, Norio Nogawa, Shin Sugiura, Takeshi Tange
    2014 Volume 97 Issue 1 Pages 51-56
    Published: February 01, 2014
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Radiocesium distribution in trees of forests in Mimamisoma, Fukushima, was studied in 2012 and 2013 after the Fukushima Daiichi Nuclear Power Plant Accident. Foliage and bark contained the most of radiocesium in each tree. A relatively high concentration (>1 Bq/g) of radiocesium was detected in the xylem of Cryptomeria stems. At higher parts of the stems, the heartwood contained more radiocesium than the sapwood. As a stem that had been felled just before the accidental deposition also contained radiocesium in its xylem, we de- duced that the radiocesium in xylem was not transferred through the root system but likely translocated from foliage.
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  • Naoki Okada, Wataru Nakai, Shinta Ohashi, Atsushi Tanaka
    2015 Volume 97 Issue 1 Pages 57-62
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    We monitored 137Cs in litter fall, through fall and stem flow in red pine and deciduous broad-leaved forests after the Fukushima Daiichi Nuclear Power Plant Accident in Fukushima Prefecture from October 2012 to December 2013. The purpose is to elucidate the migration process of 137Cs from canopy to forest floor and to clarify the possible influence of forest type on the process. The migration process of 137Cs showed seasonality; leaf-fall and rainy seasons promoted 137Cs migration through the increase in litter fall and through fall respectively. Species composition and stand density of forests caused the difference in the amount of litter fall, through fall and stem flow, and their 137Cs concentration. The difference then changed the amount of 137Cs migration from canopy to forest floor. Total 137Cs migration from canopy to forest floor in the year 2013 were 2,457 Bq/m2 (stem flow, 41; through fall, 134; litter fall, 2,281) in the pine forest and 4,032 Bq/m2 (stem flow, 213; through fall, 600; litter fall, 3,219) in the broad-leaved forest. Litter fall had the largest contribution to the 137Cs migration in both forests. We concluded that radiocesium was localized on the forest surface at the initial deposition caused by the incident, then gradually diffused in forests while being incorporated in trees, and was incorporated in the mineral cycle in forests at 1.5 years after the incident.
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  • Tatsuhiro Nishikiori, Shoko Ito, Hideki Tsuji, Tetsuo Yasutaka, Seiji ...
    2015 Volume 97 Issue 1 Pages 63-69
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Supplementary material
    To examine the degree of 137Cs wash-off from forest floor, we monitored the amount of particulate and dissolved 137Cs in surface runoff water from three m2 of experimental plots installed on slopes of 37-39° in four forests with different floor covering in Fukushima Prefecture. Plots were monitored for 145 days from May to October, 2013. A maximum of 1.1% of the 137Cs inventory in soil was washed off, with the amounts differing by up to 10-fold between the plots. The largest amount was observed in Japanese cypress forest, followed by deciduous broadleaf forest, Japanese red pine forest and Japanese cedar forest. Most (more than 96%) of the 137Cs washed off was associated with particles. The amount of soil loss was relatively large in forests with little understory and/or organic horizon, suggesting that the forest floor covering strongly affected 137Cs wash-off. In both suspended solids in surface runoff water and stream water, the activity concentration of 137Cs correlated positively with the organic matter amount, suggesting that some of the 137Cs in stream came from forest floor and that the organic horizon was an important source of the 137Cs. Japanese cypress forest is prone to poor floor covering but covers a small area of Fukushima Prefecture, suggesting that the broadleaf forest floor covering, which is most widely distributed in the area, greatly influences the 137Cs wash-off from the forest.
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  • Yoshiko Ayabe, Tsutomu Kanasashi, Naoki Hijii, Chisato Takenaka
    2015 Volume 97 Issue 1 Pages 70-74
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Supplementary material
    We investigated the relationships between radiocesium activity in the soil and litter and radiocesium concentration in the web spiders collected at two forest sites in Kawamata-cho, Fukushima Prefecture. Changes in radiocesium contamination levels of the web spider over two years (2012-2013) were also monitored. At both sites, the aggregated transfer coefficient(Tag)of radiocesium from the soil into spiders in 2013 was approximately 0.005, and the radiocesium contamination level of spiders depended on the contamination level of the soil. Compared to the web spiders collected in 2012 (1.5 y after the accident), the concentration of 137Cs in spiders collected in 2013 (2.5 y after the accident) decreased by 40-50%, which was lower than that expected based on the physical attenuation of 137Cs. Although the mean level of 137Cs contamination in spiders decreased, highly 137Cs contaminated spiders were still collected in 2013, and this implies a need for a long-term monitoring of radiocesium contamination of the spider.
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Review
  • Nobuhiro Kaneko, Yao Huang,, Taizo Nakamori
    2015 Volume 97 Issue 1 Pages 75-80
    Published: February 01, 2015
    Released on J-STAGE: April 07, 2015
    JOURNAL FREE ACCESS
    Most radioactive cesium contaminating forests finally accumulates in the surface layer of soil; at the same time it circulates in the forest ecosystem. Physical decontamination methods are not appropriate in order to remove radioactive cesium, released by the Fukushima Daiichi Nuclear Power Plant Accident, from the forest. We developed a decontamination method using fungal transfer of radio cesium from soil to wood chips laid on the forest floor. When we compared the efficiency of the decontamination between the newly developed method and the phytoremediation, it was found that the new method removed up to 7% of the radioactive cesium in the forest soil, thus it was the most efficient method to decontaminate the radioactive cesium from the forest soil. We propose a method to continue forest management under radioactive contamination while maintaining the wood energy utilization; cutting down the forest, and spreading wood chips to absorb radioactive cesium, then collecting the chips from the forest, to be used as wood fuel.
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